Neuromorphic computing devices leveraging HfO_(2) and ZrO_(2) materials have recently garnered significant attention due to their potential for brain-inspired computing systems.In this study,we present a novel trilaye...Neuromorphic computing devices leveraging HfO_(2) and ZrO_(2) materials have recently garnered significant attention due to their potential for brain-inspired computing systems.In this study,we present a novel trilayer Pt/HfO_(2)/ZrO_(2-x)/HfO_(2)/TiN memristor,engineered with a ZrO_(2-x) oxygen vacancy reservoir(OVR)layer fabricated via radio frequency(RF)sputtering under controlled oxygen ambient.The incorporation of the ZrO_(2-x) OVR layer enables enhanced resistive switching characteristics,including a high ON/OFF ratio(∼8000),excellent uniformity,robust data retention(>105 s),and multilevel storage capabilities.Furthermore,the memristor demonstrates superior synaptic plasticity with linear long-term potentiation(LTP)and depression(LTD),achieving low non-linearity values of 1.36(LTP)and 0.66(LTD),and a recognition accuracy of 95.3%in an MNIST dataset simulation.The unique properties of the ZrO_(2-x) layer,particularly its ability to act as a dynamic oxygen vacancy reservoir,significantly enhance synaptic performance by stabilizing oxygen vacancy migration.These findings establish the OVR-trilayer memristor as a promising candidate for future neuromorphic computing and high-performance memory applications.展开更多
The increasing importance of high-purity isopropyl alcohol(IPA)in semiconductor processing technology has led to a higher demand for technologies capable of detecting impurities in IPA.Although accurate and various im...The increasing importance of high-purity isopropyl alcohol(IPA)in semiconductor processing technology has led to a higher demand for technologies capable of detecting impurities in IPA.Although accurate and various impurity detection technologies have been developed,most of them have limitations in real-time and repeatable detection of impurities.Herein,for the first time,surface plasmon resonance(SPR)sensor was developed utilizing graphene transferred Au film(Au/graphene)to detect sub-ppm levels of 2,4-dinitrophenol(2,4-DNP)dissolved in IPA and this sensor demonstrates the ability to detect 2,4-DNP in real-time with great reversibility.The adsorption of 2,4-DNP to graphene is found to be stronger than that for Au film because of noncovalent graphene p–p stacking interaction,and the effect of graphene is demonstrated through density function theory(DFT)calculations and enhancement in sensing performance of Au/graphene sensor.Additionally,the presence of noncovalent p–p stacking interaction between 2,4-DNP and graphene has been demonstrated by confirming the p-doping effect of graphene-based solution field-effect transistor measurements and consecutive Raman spectra analysis.This study offers experimental and theoretical insights into the adsorption kinetics of 2,4-DNP dissolved in IPA and provides promising perspectives for real-time sensing technology utilizing label-free graphene to detect impurities in high-purity cleaning agents.展开更多
Governments worldwide have implemented non-pharmaceutical interventions(NPIs)to control the spread of coronavirus disease 2019(COVID-19),and it is crucial to accurately assess the effectiveness of such measures.Many s...Governments worldwide have implemented non-pharmaceutical interventions(NPIs)to control the spread of coronavirus disease 2019(COVID-19),and it is crucial to accurately assess the effectiveness of such measures.Many studies have quantified the risk of infection transmission and used simulations to compare the risk before and after the implementation of NPIs to judge policies’effectiveness.However,the choice of metric used to quantify the risk can lead to different conclusions regarding the effectiveness of a policy.In this study,we analyze the correlation between different transmission-risk metrics,pedestrian environments,and types of infectious diseases using simulation-generated data.Our findings reveal conflicting results among five different metric types in specific environments.More specifically,we observe that,when the randomness of pedestrian trajectories in indoor spaces is low,the closeness centrality exhibits a higher correlation coefficient with infection-based metrics than with contact-based metrics.Furthermore,even within the same pedestrian environment,the likelihood of discrepancies between infection-based metrics and other metrics increases for infectious diseases with low transmission rates.These results highlight the variability in the measured effectiveness of NPIs depending on the chosen metric.To evaluate NPIs accurately,facility managers should consider the type of facility and infectious disease and not solely rely on a single metric.This study provides a simulation model as a tool for future research and improves the reliability of pedestrian-simulation-based NPI effectiveness analysis methods.展开更多
Bipolar plates(BPs)are essential multifunctional components in vanadium redox flow batteries(VRFBs)that require excellent electrical conductivity,low permeability,and strong solid support for the stack.However,convent...Bipolar plates(BPs)are essential multifunctional components in vanadium redox flow batteries(VRFBs)that require excellent electrical conductivity,low permeability,and strong solid support for the stack.However,conventional BPs are based on graphite sheets,which provide mechanical properties and corrosion resistance but have limitations in terms of electrical conductivity.Although carbon nanotubes(CNTs)have excellent properties,CNT composites with low CNT volume fractions(10–20%)have increased electrolyte permeability and limited electrical conductivity improvement,resulting in low durability and efficiency for VRFBs.This study proposes a novel concept of horizontally aligned CNT nanocomposite bipolar plate(HACN-BP)to address these issues.The HACN-BPs feature an optimized conduction path with a CNT volume fraction of 59%,resulting in reduced manufacturing time while demonstrating superior conductivity and permeability compared to conventional BPs.Furthermore,integrated HACN-BP mitigates ohmic loss that occurs in the BPs,thereby mitigating the potential drop by 40%.Therefore,the utilization of HACN-BP shows superior performance compared to recent studies,a substantial improvement of more than 6%in energy efficiency and 14%in capacity over conventional BP.展开更多
NiCoCrAlY is usually used as the material to bond-coat in thermal barrier coating systems under high temperatures.Using NiCoCrAlY and adding different amounts of the active element Ti(0,0.1,0.3,and0.5;wt%),the relatio...NiCoCrAlY is usually used as the material to bond-coat in thermal barrier coating systems under high temperatures.Using NiCoCrAlY and adding different amounts of the active element Ti(0,0.1,0.3,and0.5;wt%),the relationship between oxide peg size and thermally grown oxide spalling resistance is ascertained by examining specimens subjected to a cyclic oxidation experiment.Oxide pegs,consisting of a Y-and Ti-rich oxide core and an outer Al_(2) O_(3) sheath,are formed by Ti and A1 successively reacting with oxygen after the rapid generation of Y-rich oxide.The size of the oxide pegs with higher Ti concentrations is on average bigger in the alloy.Severe thermally grown oxide spalling occurred in the0.5 wt% Ti specimen,but in the 0.3 wt% Ti specimen,it displayed the best adherence with the alloy due to the presence of fine pegs.Cavities existed at the interface between the inner oxide core and outer Al_(2) O_(3) sheath of larger pegs serve as microcrack sources and further induce severe scale failure combined with the initial interface crack between the scale and alloy.展开更多
In this study,high entropy metallic glasses(HEMGs)were developed through a combination of concepts for designing metallic glasses(main element+transition metal+metalloid element)and high-entropy alloys(more than five ...In this study,high entropy metallic glasses(HEMGs)were developed through a combination of concepts for designing metallic glasses(main element+transition metal+metalloid element)and high-entropy alloys(more than five elements,each element having an atomic concentration between 5 at.%and 35 at.%).The developed metallic glass alloys are composed of Co-Fe-Ni main elements,transition metals(Cr,Mo)and metalloid elements(C,B).Moreover,the present work reports the thermal,mechanical and magnetic properties of(CoFeNi)(50)(CrMo)(50-x)(CB)x alloys with x=20,25,30.The developed as-spun HEMGs exhibit typical paramagnetic properties even for a high amount of ferromagnetic elements(Co,Fe,and Ni)and have high elastic modulus(103–160 GPa)and hardness(14–27 GPa),thus possessing mechanical properties similar to well-known Co-based metallic glasses(Co-Cr-Mo-C-B system).In addition,some of the bulk samples prepared with a diameter of 2 mm form bulk metallic glasses with a high compressive strength around 3.5 GPa.The mechanisms determining the stability of the supercooled liquid,as well as the paramagnetic and mechanical properties for the developed non-equiatomic HEMGs,are discussed.展开更多
The cell-type continuous electromagnetic radiation system is a demonstration device capable of generating high-power millimeter electromagnetic waves of a specific wavelength and observing their effects on living orga...The cell-type continuous electromagnetic radiation system is a demonstration device capable of generating high-power millimeter electromagnetic waves of a specific wavelength and observing their effects on living organisms.It irradiates a biological sample placed in a 30×30×50 cm^(3)cell with electromagnetic waves in the 3.15-mm-wavelength region(with an output of≥1 W)and analyzes the temperature change of the sample.A vacuum electronic device-based coupled-cavity backward-wave oscillator converts the electron energy of the electron beam into radiofrequency(RF)energy and radiates it to the target through an antenna,increasing the temperature through the absorption of RF energy in the skin.The system causes pain and ultimately reduces combat power.A cell-type continuous electromagnetic radiation system consisting of four parts—an electromagnetic-wave generator,a highvoltage power supply,a test cell,and a system controller—generates an RF signal of≥1 W in a continuous waveform at a 95-GHz center frequency,as well as a chemical solution with a dielectric constant similar to that of the skin of a living organism.An increase of 5°C lasting approximately 10 s was confirmed through an experiment.展开更多
Recently,automotive intrusion detection systems(IDSs)have emerged as promising defense approaches to counter attacks on in-vehicle networks(IVNs).However,the effectiveness of IDSs relies heavily on the quality of the ...Recently,automotive intrusion detection systems(IDSs)have emerged as promising defense approaches to counter attacks on in-vehicle networks(IVNs).However,the effectiveness of IDSs relies heavily on the quality of the datasets used for training and evaluation.Despite the availability of several datasets for automotive IDSs,there has been a lack of comprehensive analysis focusing on assessing these datasets.This paper aims to address the need for dataset assessment in the context of automotive IDSs.It proposes qualitative and quantitative metrics that are independent of specific automotive IDSs,to evaluate the quality of datasets.These metrics take into consideration various aspects such as dataset description,collection environment,and attack complexity.This paper evaluates eight commonly used datasets for automotive IDSs using the proposed metrics.The evaluation reveals biases in the datasets,particularly in terms of limited contexts and lack of diversity.Additionally,it highlights that the attacks in the datasets were mostly injected without considering normal behaviors,which poses challenges for training and evaluating machine learning-based IDSs.This paper emphasizes the importance of addressing the identified limitations in existing datasets to improve the performance and adaptability of automotive IDSs.The proposed metrics can serve as valuable guidelines for researchers and practitioners in selecting and constructing high-quality datasets for automotive security applications.Finally,this paper presents the requirements for high-quality datasets,including the need for representativeness,diversity,and balance.展开更多
The spontaneously generated electrical charge of a droplet dispensed from conventional pipetting is undesirable and unpredictable for most experiments that use pipetting.Hence,a method for controlling and removing the...The spontaneously generated electrical charge of a droplet dispensed from conventional pipetting is undesirable and unpredictable for most experiments that use pipetting.Hence,a method for controlling and removing the electrical charge needs to be developed.In this study,by using the electrode-deposited pipet tip(E-pipet tip),the charge-controlling system is newly developed and the electrical charge of a droplet is precisely controlled.The effect of electrolyte concentration and volume of the transferred solution to the electrical charge of a dispensed droplet is theoretically and experimentally investigated by using the equivalent capacitor model.Furthermore,a proof-of-concept example of the self-alignment and self-assembly of sequentially dispensed multiple droplets is demonstrated as one of the potential applications.Given that the electrical charge of the various aqueous droplets can be precisely and simply controlled,the fabricated E-pipet tip can be broadly utilized not only as a general charge-controlling platform of aqueous droplets but also as a powerful tool to explore fundamental scientific research regarding electrical charge of a droplet,such as the surface oscillation and evaporation of charged droplets.展开更多
Packet duplication(PD)with dual connectivity(DC)was newly introduced in the 5G New Radio(NR)specifications to meet the stringent ultra reliable low latency communication(URLLC)requirements.PD technology uses duplicate...Packet duplication(PD)with dual connectivity(DC)was newly introduced in the 5G New Radio(NR)specifications to meet the stringent ultra reliable low latency communication(URLLC)requirements.PD technology uses duplicated packets in the packet data convergence protocol(PDCP)layer that are transmitted via two different access nodes(ANs)to the user equipment(UE)in order to enhance the reliability performance.However,PD can result in unnecessary retransmissions in the lower layers since the hybrid automatic retransmission request(HARQ)operation is unaware of the transmission success achieved through the alternate DC link to the UE.To overcome this issue,in this paper,a novel duplication-aware retransmission optimization(DRO)scheme is proposed to reduce the resource usage induced by unnecessary HARQ retransmissions.The proposed DRO scheme can minimize the average channel use while satisfying the URLLC requirements.The proposed DRO scheme derives the optimal HARQ retransmission attempts for different ANs by solving a nonlinear integer programming(NLIP)problem.The performance of the proposed DRO scheme was evaluated using MATLAB simulation and is compared to the existing 5G HARQ support schemes.The simulations results show that the proposed DRO scheme can provide a 14.71%and 15.11%reduced average channel use gain compared to the selective data duplication upon failure(SDUF)scheme and latency-aware dynamic multi-connectivity algorithm(LADMA)scheme,respectively,which are the existing 5G PD schemes that use HARQ.展开更多
Self-assembly of silicon nanowire(SiNW)arrays is studied using SF_(6)/0_(2)plasma treatment.The self-assembly method can be applied to single-and poly-crystalline Si substrates.Plasma conditions can control the length...Self-assembly of silicon nanowire(SiNW)arrays is studied using SF_(6)/0_(2)plasma treatment.The self-assembly method can be applied to single-and poly-crystalline Si substrates.Plasma conditions can control the length and diameter of the SiNW arrays.Lower reflectance of the wire arrays over the wavelength range 200-1100nm is obtained.The conducting transparent indium-tin-oxide(ITO)electrode can be fully coated on the self-assembled SiNW arrays by sputtering.The ITO-coated SiNW solar cells show the same low surface light reflectance and a higher carrier collection efficiency than SiNW solar cells without ITO coating.An efficiency enhancement of around 3 times for ITO coated SiNW solar cells is demonstrated via experiments.展开更多
We consider an H∞ synchronization problem in nonlinear Bloch systems. Based on Lyapunov stability theory and linear matrix inequality formulation, a dynamic feedback controller is designed to guarantee asymptotic sta...We consider an H∞ synchronization problem in nonlinear Bloch systems. Based on Lyapunov stability theory and linear matrix inequality formulation, a dynamic feedback controller is designed to guarantee asymptotic stability of the master-slave synchronization. Moreover, this controller reduces the effect of an external disturbance to the H∞ norm constraint. A numerical example is given to validate the proposed synchronization scheme.展开更多
In this study, two Heracron? woven fabrics, HT840-1 and HT840-2, were fabricated with different multifilament fibers, and their resistance to ballistic impact was investigated. For the same weight and number of plies,...In this study, two Heracron? woven fabrics, HT840-1 and HT840-2, were fabricated with different multifilament fibers, and their resistance to ballistic impact was investigated. For the same weight and number of plies, the HT840-2 fabric showed improved ballistic properties, compared with HT840-1;this result is contrary to the fiber and fabric properties. With the exception of the yarn’s physical properties, this behavior can be explained in terms of the number of multifilaments, which strongly influenced the ballistic mechanism, i.e., a greater number of multifilament fibers facilitates energy dissipation from a high-speed ballistic projectile. In summary, establishing this optimal number of multifilaments is the key to optimizing the ballistic properties of any given fabric.展开更多
It is demonstrated that inherent coating adhesion and damage threshold are correlated for Ta2O5 and HfO2 coatings widely used in optoelectronic devices. By utilizing a newly proposed 1-h boiling water test combined wi...It is demonstrated that inherent coating adhesion and damage threshold are correlated for Ta2O5 and HfO2 coatings widely used in optoelectronic devices. By utilizing a newly proposed 1-h boiling water test combined with the optical aging under high-power laser irradiation, we show that an optical coating that survives the 1-h boiling water test withstands the damage threshold, ensuring the field service life even in harsh environments. Besides the standard evaluation methods, which may have limitations for applications required in harsh environments, the 1-h boiling water test can serve as an alternative method of reliability assessment for optical coatings. A heuristics herein can be used as a gating item for qualification of optical coatings for various applications.展开更多
This paper presents a free market economy model that can be used to facilitate fully distributed autonomous control of resources in massive heterogeneous wireless sensor networks (WSNs). In the future, it is expected ...This paper presents a free market economy model that can be used to facilitate fully distributed autonomous control of resources in massive heterogeneous wireless sensor networks (WSNs). In the future, it is expected that WSNs will exist as part of the global Internet of Things (IoT), and different WSNs can work together in a massive network of heterogeneous WSNs in order to solve common problems. Control of valuable processing, sensing and communication resources, determining which nodes will remain awake during specific time periods in order to provide sensing services, and determining which nodes will forward other nodes’ packets are difficult problems that must be dealt with. It is proposed that just as the free market economy model enables the global human society to function reasonably well when individuals simply attempt to trade money and services in order to maximize their individual profits, and a similar model and mechanism should enable a massive network of heterogeneous WSNs to function well in a fully distributed autonomous manner. The main contributions of this paper are the introduction of the free market economy model for use with WSNs, the formal definition of a maximum profit price problem for multihop packet relaying, and the proposal of a distributed genetic algorithm for the solution of the maximum profit price problem. Simulation results show that the proposed distributed solution produces results that are 70% - 80% similar to a pareto optimal solution for this problem.展开更多
The functionalities and diverse metastable phases of multiferroic BiFeO_(3)(BFO)thin films depend on the misfit strain.Although mixed phase-induced strain relaxation in multiphase BFO thin films is well known,it is un...The functionalities and diverse metastable phases of multiferroic BiFeO_(3)(BFO)thin films depend on the misfit strain.Although mixed phase-induced strain relaxation in multiphase BFO thin films is well known,it is unclear whether a singlecrystalline BFO thin film can accommodate misfit strain without the involvement of its polymorphs.Thus,understanding the strain relaxation behavior is key to elucidating the lattice strain–property relationship.In this study,a correlative strain analysis based on dark-field inline electron holography(DIH)and quantitative scanning transmission electron microscopy(STEM)was performed to reveal the structural mechanism for strain accommodation of a single-crystalline BFO thin film.The nanoscale DIH strain analysis results indicated a random combination of multiple strain states that acted as a primary strain relief,forming irregularly strained nanodomains.The STEM-based bond length measurement of the corresponding strained nanodomains revealed a unique strain accommodation behavior achieved by a statistical combination of multiple modes of distorted structures on the unit-cell scale.The globally integrated strain for each nanodomain was estimated to be close to1.5%,irrespective of the nanoscale strain states,which was consistent with the fully strained BFO film on the SrTiO_(3) substrate.Density functional theory calculations suggested that strain accommodation by the combination of metastable phases was energetically favored compared to single-phase-mediated relaxation.This discovery allows a comprehensive understanding of strain accommodation behavior in ferroelectric oxide films,such as BFO,with various low-symmetry polymorphs.展开更多
Due to typesetting mistake,Hanul Min was missed to be denoted as a corresponding author in the article.The type-setter apologizes for this.The original article has been corrected.Open Access This article is licensed u...Due to typesetting mistake,Hanul Min was missed to be denoted as a corresponding author in the article.The type-setter apologizes for this.The original article has been corrected.Open Access This article is licensed under a Creative Commons Attribution 4.0 International License,which permits use,sharing,adaptation,distribution and reproduction in any medium or format,as long as you give appropriate credit to the original author(s)and the source,provide a link to the Creative Commons licence,and indicate if changes were made.The images or other third party material in this article are included in the article’s Creative Commons licence,unless indicated otherwise in a credit line to the material.If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use,you will need to obtain permission directly from the copyright holder.展开更多
Artificial sensory systems(ASS)are pivotal to next-generation extended reality technologies,now evolving into flexible platforms for comfortable wear and immersive user experiences,while ensuring high performance and ...Artificial sensory systems(ASS)are pivotal to next-generation extended reality technologies,now evolving into flexible platforms for comfortable wear and immersive user experiences,while ensuring high performance and operational reliability.To address these demands,metal-based nanoparticles(NPs),such as noble metal,oxide,and multi-elemental NPs,have been extensively incorporated into functional materials of sensory and synaptic devices due to their tunable optical,electrical,and chemical properties,enhancing sensory precision,stability,and environmental adaptability.However,traditional NP fabrication methods often involve complex processing,residual contaminants,and scalability issues,limiting their effectiveness in ASS applications.State-of-the-art laser ablation in liquids(LAL)presents a promising alternative,offering scalable production of surfactant-free NPs with customizable physicochemical properties,though their application in electronics remains underexplored.This review delves into the transformative potential of LAL-fabricated NPs in ASS,covering the fundamental mechanisms of LAL,the role of process parameters,the derivative strategies for size modulation,the diversity of metal-based NPs,their applications in sensory and synaptic devices,and the challenges and perspectives for meeting industrial standards.Bridging the gap between LAL and ASS is poised to revolutionize both industrial manufacturing and academic research by offering scalable solutions to overcome intrinsic tradeoffs between flexibility and performance,fostering innovations in human-centric,immersive electronics.展开更多
Soft robots have partially or entirely provided versatile opportunities for issues or roles that cannot be addressed by conventional machine robots,although most studies are limited to designs,controls,or physical/mec...Soft robots have partially or entirely provided versatile opportunities for issues or roles that cannot be addressed by conventional machine robots,although most studies are limited to designs,controls,or physical/mechanical motions.Here,we present a transformable,reconfigurable robotic platform created by the integration of magnetically responsive soft composite matrices with deformable multifunctional electronics.Magnetic compounds engineered to undergo phase transition at a low temperature can readily achieve reversible magnetization and conduct various changes of motions and shapes.Thin and flexible electronic system designed with mechanical dynamics does not interfere with movements of the soft electronic robot,and the performances of wireless circuit,sensors,and devices are independent of a variety of activities,all of which are verified by theoretical studies.Demonstration of navigations and electronic operations in an artificial track highlights the potential of the integrated soft robot for on-demand,environments-responsive movements/metamorphoses,and optoelectrical detection and stimulation.Further improvements to a miniaturized,sophisticated system with material options enable in situ monitoring and treatment in envisioned areas such as biomedical implants.展开更多
基金financially supported by the National Research Foundation of Korea(no.NRF-2021R1A2C2010781)grant funded by the Korean Government(Ministry of Science and ICT)Korea Institute for Advancement of Technology(KIAT)grant funded by the Korea Government(MOTIE)(no.P0012451,The Competency Development Program for Industry Specialist)Korea Government(MOTIE)(no.P0020966,HRD Program for Industrial Innovation).
文摘Neuromorphic computing devices leveraging HfO_(2) and ZrO_(2) materials have recently garnered significant attention due to their potential for brain-inspired computing systems.In this study,we present a novel trilayer Pt/HfO_(2)/ZrO_(2-x)/HfO_(2)/TiN memristor,engineered with a ZrO_(2-x) oxygen vacancy reservoir(OVR)layer fabricated via radio frequency(RF)sputtering under controlled oxygen ambient.The incorporation of the ZrO_(2-x) OVR layer enables enhanced resistive switching characteristics,including a high ON/OFF ratio(∼8000),excellent uniformity,robust data retention(>105 s),and multilevel storage capabilities.Furthermore,the memristor demonstrates superior synaptic plasticity with linear long-term potentiation(LTP)and depression(LTD),achieving low non-linearity values of 1.36(LTP)and 0.66(LTD),and a recognition accuracy of 95.3%in an MNIST dataset simulation.The unique properties of the ZrO_(2-x) layer,particularly its ability to act as a dynamic oxygen vacancy reservoir,significantly enhance synaptic performance by stabilizing oxygen vacancy migration.These findings establish the OVR-trilayer memristor as a promising candidate for future neuromorphic computing and high-performance memory applications.
基金financially supported by National R&D Program(RS-2024-00405016)Nano Material Technology Development Program(2022M3HA1A01011993)financially supported by Samsung Electronics Co.,Ltd.
文摘The increasing importance of high-purity isopropyl alcohol(IPA)in semiconductor processing technology has led to a higher demand for technologies capable of detecting impurities in IPA.Although accurate and various impurity detection technologies have been developed,most of them have limitations in real-time and repeatable detection of impurities.Herein,for the first time,surface plasmon resonance(SPR)sensor was developed utilizing graphene transferred Au film(Au/graphene)to detect sub-ppm levels of 2,4-dinitrophenol(2,4-DNP)dissolved in IPA and this sensor demonstrates the ability to detect 2,4-DNP in real-time with great reversibility.The adsorption of 2,4-DNP to graphene is found to be stronger than that for Au film because of noncovalent graphene p–p stacking interaction,and the effect of graphene is demonstrated through density function theory(DFT)calculations and enhancement in sensing performance of Au/graphene sensor.Additionally,the presence of noncovalent p–p stacking interaction between 2,4-DNP and graphene has been demonstrated by confirming the p-doping effect of graphene-based solution field-effect transistor measurements and consecutive Raman spectra analysis.This study offers experimental and theoretical insights into the adsorption kinetics of 2,4-DNP dissolved in IPA and provides promising perspectives for real-time sensing technology utilizing label-free graphene to detect impurities in high-purity cleaning agents.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Ministry of Science and ICT(MSIT),Republic of Korea(1711185759).
文摘Governments worldwide have implemented non-pharmaceutical interventions(NPIs)to control the spread of coronavirus disease 2019(COVID-19),and it is crucial to accurately assess the effectiveness of such measures.Many studies have quantified the risk of infection transmission and used simulations to compare the risk before and after the implementation of NPIs to judge policies’effectiveness.However,the choice of metric used to quantify the risk can lead to different conclusions regarding the effectiveness of a policy.In this study,we analyze the correlation between different transmission-risk metrics,pedestrian environments,and types of infectious diseases using simulation-generated data.Our findings reveal conflicting results among five different metric types in specific environments.More specifically,we observe that,when the randomness of pedestrian trajectories in indoor spaces is low,the closeness centrality exhibits a higher correlation coefficient with infection-based metrics than with contact-based metrics.Furthermore,even within the same pedestrian environment,the likelihood of discrepancies between infection-based metrics and other metrics increases for infectious diseases with low transmission rates.These results highlight the variability in the measured effectiveness of NPIs depending on the chosen metric.To evaluate NPIs accurately,facility managers should consider the type of facility and infectious disease and not solely rely on a single metric.This study provides a simulation model as a tool for future research and improves the reliability of pedestrian-simulation-based NPI effectiveness analysis methods.
基金supported by the Nano&Material Technology Development Program through the National R&D Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(RS-202300260461).
文摘Bipolar plates(BPs)are essential multifunctional components in vanadium redox flow batteries(VRFBs)that require excellent electrical conductivity,low permeability,and strong solid support for the stack.However,conventional BPs are based on graphite sheets,which provide mechanical properties and corrosion resistance but have limitations in terms of electrical conductivity.Although carbon nanotubes(CNTs)have excellent properties,CNT composites with low CNT volume fractions(10–20%)have increased electrolyte permeability and limited electrical conductivity improvement,resulting in low durability and efficiency for VRFBs.This study proposes a novel concept of horizontally aligned CNT nanocomposite bipolar plate(HACN-BP)to address these issues.The HACN-BPs feature an optimized conduction path with a CNT volume fraction of 59%,resulting in reduced manufacturing time while demonstrating superior conductivity and permeability compared to conventional BPs.Furthermore,integrated HACN-BP mitigates ohmic loss that occurs in the BPs,thereby mitigating the potential drop by 40%.Therefore,the utilization of HACN-BP shows superior performance compared to recent studies,a substantial improvement of more than 6%in energy efficiency and 14%in capacity over conventional BP.
基金financially supported by the Tsinghua University Initiative Scientific Research Program and the National Magnetic Confinement Fusion Energy Research Project of China(No.2015GB118001)。
文摘NiCoCrAlY is usually used as the material to bond-coat in thermal barrier coating systems under high temperatures.Using NiCoCrAlY and adding different amounts of the active element Ti(0,0.1,0.3,and0.5;wt%),the relationship between oxide peg size and thermally grown oxide spalling resistance is ascertained by examining specimens subjected to a cyclic oxidation experiment.Oxide pegs,consisting of a Y-and Ti-rich oxide core and an outer Al_(2) O_(3) sheath,are formed by Ti and A1 successively reacting with oxygen after the rapid generation of Y-rich oxide.The size of the oxide pegs with higher Ti concentrations is on average bigger in the alloy.Severe thermally grown oxide spalling occurred in the0.5 wt% Ti specimen,but in the 0.3 wt% Ti specimen,it displayed the best adherence with the alloy due to the presence of fine pegs.Cavities existed at the interface between the inner oxide core and outer Al_(2) O_(3) sheath of larger pegs serve as microcrack sources and further induce severe scale failure combined with the initial interface crack between the scale and alloy.
基金supported by the Technology Innovation Program(No.10063052,Development of advanced nano-micron coating material and coated cutting tool for Hard-to-Cut)funded By Ministry of Trade,Industry and Energy(MOTIE,Korea)+1 种基金the Basic Research Laboratory Program through the Ministry of Education of the Republic of Korea(No.2019R1A4A1026125)support through the European Research Council under the Advanced Grant“INTERLHYB”—Next Generation of Complex Metallic Materials in Intelligent Hybrid Structures”(No.ERC-2013-ADG-340025)is gratefully acknowledged。
文摘In this study,high entropy metallic glasses(HEMGs)were developed through a combination of concepts for designing metallic glasses(main element+transition metal+metalloid element)and high-entropy alloys(more than five elements,each element having an atomic concentration between 5 at.%and 35 at.%).The developed metallic glass alloys are composed of Co-Fe-Ni main elements,transition metals(Cr,Mo)and metalloid elements(C,B).Moreover,the present work reports the thermal,mechanical and magnetic properties of(CoFeNi)(50)(CrMo)(50-x)(CB)x alloys with x=20,25,30.The developed as-spun HEMGs exhibit typical paramagnetic properties even for a high amount of ferromagnetic elements(Co,Fe,and Ni)and have high elastic modulus(103–160 GPa)and hardness(14–27 GPa),thus possessing mechanical properties similar to well-known Co-based metallic glasses(Co-Cr-Mo-C-B system).In addition,some of the bulk samples prepared with a diameter of 2 mm form bulk metallic glasses with a high compressive strength around 3.5 GPa.The mechanisms determining the stability of the supercooled liquid,as well as the paramagnetic and mechanical properties for the developed non-equiatomic HEMGs,are discussed.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.NRF-2021M2E8A1038938,No.NRF-2021R1F1A1048374,and No.NRF-2016R1A3B1908336)supported by a grant of the Korea Institute of Radiological and Medical Sciences(KIRAMS),funded by the Ministry of Science and ICT(MSIT),Republic of Korea(No.50051—2021,No.50623—2021)。
文摘The cell-type continuous electromagnetic radiation system is a demonstration device capable of generating high-power millimeter electromagnetic waves of a specific wavelength and observing their effects on living organisms.It irradiates a biological sample placed in a 30×30×50 cm^(3)cell with electromagnetic waves in the 3.15-mm-wavelength region(with an output of≥1 W)and analyzes the temperature change of the sample.A vacuum electronic device-based coupled-cavity backward-wave oscillator converts the electron energy of the electron beam into radiofrequency(RF)energy and radiates it to the target through an antenna,increasing the temperature through the absorption of RF energy in the skin.The system causes pain and ultimately reduces combat power.A cell-type continuous electromagnetic radiation system consisting of four parts—an electromagnetic-wave generator,a highvoltage power supply,a test cell,and a system controller—generates an RF signal of≥1 W in a continuous waveform at a 95-GHz center frequency,as well as a chemical solution with a dielectric constant similar to that of the skin of a living organism.An increase of 5°C lasting approximately 10 s was confirmed through an experiment.
基金supported in part by the 2021 Autonomous Driving Development Innovation Project of the Ministry of Science and ICT,‘Development of Technology for Security and Ultra-High-Speed Integrity of the Next-Generation Internal Net-Work of Autonomous Vehicles’(No.2021-0-01348)and in part by the National Research Foundation of Korea(NRF)grant funded by the Korean Government Ministry of Science and ICT(MSIT)under Grant NRF-2021R1A2C2014428.
文摘Recently,automotive intrusion detection systems(IDSs)have emerged as promising defense approaches to counter attacks on in-vehicle networks(IVNs).However,the effectiveness of IDSs relies heavily on the quality of the datasets used for training and evaluation.Despite the availability of several datasets for automotive IDSs,there has been a lack of comprehensive analysis focusing on assessing these datasets.This paper aims to address the need for dataset assessment in the context of automotive IDSs.It proposes qualitative and quantitative metrics that are independent of specific automotive IDSs,to evaluate the quality of datasets.These metrics take into consideration various aspects such as dataset description,collection environment,and attack complexity.This paper evaluates eight commonly used datasets for automotive IDSs using the proposed metrics.The evaluation reveals biases in the datasets,particularly in terms of limited contexts and lack of diversity.Additionally,it highlights that the attacks in the datasets were mostly injected without considering normal behaviors,which poses challenges for training and evaluating machine learning-based IDSs.This paper emphasizes the importance of addressing the identified limitations in existing datasets to improve the performance and adaptability of automotive IDSs.The proposed metrics can serve as valuable guidelines for researchers and practitioners in selecting and constructing high-quality datasets for automotive security applications.Finally,this paper presents the requirements for high-quality datasets,including the need for representativeness,diversity,and balance.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIP).(No.2014R1A2A1A010065272011-0030075+1 种基金2012R1A2A2A06047424)supported by the convergence technology development program for bionic arm through the National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT&Future Planning(No.2014M3C1B2048632)
文摘The spontaneously generated electrical charge of a droplet dispensed from conventional pipetting is undesirable and unpredictable for most experiments that use pipetting.Hence,a method for controlling and removing the electrical charge needs to be developed.In this study,by using the electrode-deposited pipet tip(E-pipet tip),the charge-controlling system is newly developed and the electrical charge of a droplet is precisely controlled.The effect of electrolyte concentration and volume of the transferred solution to the electrical charge of a dispensed droplet is theoretically and experimentally investigated by using the equivalent capacitor model.Furthermore,a proof-of-concept example of the self-alignment and self-assembly of sequentially dispensed multiple droplets is demonstrated as one of the potential applications.Given that the electrical charge of the various aqueous droplets can be precisely and simply controlled,the fabricated E-pipet tip can be broadly utilized not only as a general charge-controlling platform of aqueous droplets but also as a powerful tool to explore fundamental scientific research regarding electrical charge of a droplet,such as the surface oscillation and evaporation of charged droplets.
基金This work was supported by the Institute of Information&communications Technology Planning&Evaluation(IITP)grant funded by the SouthKorea government(MSIT,2021-0-00040,Development of intelligent stealth technology for information and communication resources for public affairs and missions).
文摘Packet duplication(PD)with dual connectivity(DC)was newly introduced in the 5G New Radio(NR)specifications to meet the stringent ultra reliable low latency communication(URLLC)requirements.PD technology uses duplicated packets in the packet data convergence protocol(PDCP)layer that are transmitted via two different access nodes(ANs)to the user equipment(UE)in order to enhance the reliability performance.However,PD can result in unnecessary retransmissions in the lower layers since the hybrid automatic retransmission request(HARQ)operation is unaware of the transmission success achieved through the alternate DC link to the UE.To overcome this issue,in this paper,a novel duplication-aware retransmission optimization(DRO)scheme is proposed to reduce the resource usage induced by unnecessary HARQ retransmissions.The proposed DRO scheme can minimize the average channel use while satisfying the URLLC requirements.The proposed DRO scheme derives the optimal HARQ retransmission attempts for different ANs by solving a nonlinear integer programming(NLIP)problem.The performance of the proposed DRO scheme was evaluated using MATLAB simulation and is compared to the existing 5G HARQ support schemes.The simulations results show that the proposed DRO scheme can provide a 14.71%and 15.11%reduced average channel use gain compared to the selective data duplication upon failure(SDUF)scheme and latency-aware dynamic multi-connectivity algorithm(LADMA)scheme,respectively,which are the existing 5G PD schemes that use HARQ.
文摘Self-assembly of silicon nanowire(SiNW)arrays is studied using SF_(6)/0_(2)plasma treatment.The self-assembly method can be applied to single-and poly-crystalline Si substrates.Plasma conditions can control the length and diameter of the SiNW arrays.Lower reflectance of the wire arrays over the wavelength range 200-1100nm is obtained.The conducting transparent indium-tin-oxide(ITO)electrode can be fully coated on the self-assembled SiNW arrays by sputtering.The ITO-coated SiNW solar cells show the same low surface light reflectance and a higher carrier collection efficiency than SiNW solar cells without ITO coating.An efficiency enhancement of around 3 times for ITO coated SiNW solar cells is demonstrated via experiments.
基金Project supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education,Science and Technology (Grant No.2010-0009373)
文摘We consider an H∞ synchronization problem in nonlinear Bloch systems. Based on Lyapunov stability theory and linear matrix inequality formulation, a dynamic feedback controller is designed to guarantee asymptotic stability of the master-slave synchronization. Moreover, this controller reduces the effect of an external disturbance to the H∞ norm constraint. A numerical example is given to validate the proposed synchronization scheme.
文摘In this study, two Heracron? woven fabrics, HT840-1 and HT840-2, were fabricated with different multifilament fibers, and their resistance to ballistic impact was investigated. For the same weight and number of plies, the HT840-2 fabric showed improved ballistic properties, compared with HT840-1;this result is contrary to the fiber and fabric properties. With the exception of the yarn’s physical properties, this behavior can be explained in terms of the number of multifilaments, which strongly influenced the ballistic mechanism, i.e., a greater number of multifilament fibers facilitates energy dissipation from a high-speed ballistic projectile. In summary, establishing this optimal number of multifilaments is the key to optimizing the ballistic properties of any given fabric.
文摘It is demonstrated that inherent coating adhesion and damage threshold are correlated for Ta2O5 and HfO2 coatings widely used in optoelectronic devices. By utilizing a newly proposed 1-h boiling water test combined with the optical aging under high-power laser irradiation, we show that an optical coating that survives the 1-h boiling water test withstands the damage threshold, ensuring the field service life even in harsh environments. Besides the standard evaluation methods, which may have limitations for applications required in harsh environments, the 1-h boiling water test can serve as an alternative method of reliability assessment for optical coatings. A heuristics herein can be used as a gating item for qualification of optical coatings for various applications.
文摘This paper presents a free market economy model that can be used to facilitate fully distributed autonomous control of resources in massive heterogeneous wireless sensor networks (WSNs). In the future, it is expected that WSNs will exist as part of the global Internet of Things (IoT), and different WSNs can work together in a massive network of heterogeneous WSNs in order to solve common problems. Control of valuable processing, sensing and communication resources, determining which nodes will remain awake during specific time periods in order to provide sensing services, and determining which nodes will forward other nodes’ packets are difficult problems that must be dealt with. It is proposed that just as the free market economy model enables the global human society to function reasonably well when individuals simply attempt to trade money and services in order to maximize their individual profits, and a similar model and mechanism should enable a massive network of heterogeneous WSNs to function well in a fully distributed autonomous manner. The main contributions of this paper are the introduction of the free market economy model for use with WSNs, the formal definition of a maximum profit price problem for multihop packet relaying, and the proposal of a distributed genetic algorithm for the solution of the maximum profit price problem. Simulation results show that the proposed distributed solution produces results that are 70% - 80% similar to a pareto optimal solution for this problem.
基金Samsung Research Fundings&Incubation Center of Samsung Electronics(Grant No.SRFCMA1702-01)Y.-M.K acknowledges partial support from the National Research Foundation of Korea(NRF)(Grant No.2023R1A2C2002403)funded by the Korean government in KoreaA.Borisevich acknowledges support from FaCT,an Energy Frontier Research Center funded by the U.S.Department of Energy,Office of Science,Office of Basic Energy Science,Collaboratives Research Division.
文摘The functionalities and diverse metastable phases of multiferroic BiFeO_(3)(BFO)thin films depend on the misfit strain.Although mixed phase-induced strain relaxation in multiphase BFO thin films is well known,it is unclear whether a singlecrystalline BFO thin film can accommodate misfit strain without the involvement of its polymorphs.Thus,understanding the strain relaxation behavior is key to elucidating the lattice strain–property relationship.In this study,a correlative strain analysis based on dark-field inline electron holography(DIH)and quantitative scanning transmission electron microscopy(STEM)was performed to reveal the structural mechanism for strain accommodation of a single-crystalline BFO thin film.The nanoscale DIH strain analysis results indicated a random combination of multiple strain states that acted as a primary strain relief,forming irregularly strained nanodomains.The STEM-based bond length measurement of the corresponding strained nanodomains revealed a unique strain accommodation behavior achieved by a statistical combination of multiple modes of distorted structures on the unit-cell scale.The globally integrated strain for each nanodomain was estimated to be close to1.5%,irrespective of the nanoscale strain states,which was consistent with the fully strained BFO film on the SrTiO_(3) substrate.Density functional theory calculations suggested that strain accommodation by the combination of metastable phases was energetically favored compared to single-phase-mediated relaxation.This discovery allows a comprehensive understanding of strain accommodation behavior in ferroelectric oxide films,such as BFO,with various low-symmetry polymorphs.
文摘Due to typesetting mistake,Hanul Min was missed to be denoted as a corresponding author in the article.The type-setter apologizes for this.The original article has been corrected.Open Access This article is licensed under a Creative Commons Attribution 4.0 International License,which permits use,sharing,adaptation,distribution and reproduction in any medium or format,as long as you give appropriate credit to the original author(s)and the source,provide a link to the Creative Commons licence,and indicate if changes were made.The images or other third party material in this article are included in the article’s Creative Commons licence,unless indicated otherwise in a credit line to the material.If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use,you will need to obtain permission directly from the copyright holder.
基金supported by the Nano&Material Technology Development Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(Grant Nos.RS-2024-00403639 and RS2024-00411904)。
文摘Artificial sensory systems(ASS)are pivotal to next-generation extended reality technologies,now evolving into flexible platforms for comfortable wear and immersive user experiences,while ensuring high performance and operational reliability.To address these demands,metal-based nanoparticles(NPs),such as noble metal,oxide,and multi-elemental NPs,have been extensively incorporated into functional materials of sensory and synaptic devices due to their tunable optical,electrical,and chemical properties,enhancing sensory precision,stability,and environmental adaptability.However,traditional NP fabrication methods often involve complex processing,residual contaminants,and scalability issues,limiting their effectiveness in ASS applications.State-of-the-art laser ablation in liquids(LAL)presents a promising alternative,offering scalable production of surfactant-free NPs with customizable physicochemical properties,though their application in electronics remains underexplored.This review delves into the transformative potential of LAL-fabricated NPs in ASS,covering the fundamental mechanisms of LAL,the role of process parameters,the derivative strategies for size modulation,the diversity of metal-based NPs,their applications in sensory and synaptic devices,and the challenges and perspectives for meeting industrial standards.Bridging the gap between LAL and ASS is poised to revolutionize both industrial manufacturing and academic research by offering scalable solutions to overcome intrinsic tradeoffs between flexibility and performance,fostering innovations in human-centric,immersive electronics.
基金supported by the Korea Institute of Science and Technology(KIST)Institutional Program(Project No.2E32501-23-106)the National Research Foundation of Korea(NRF)grant funded by the Korea government(the Ministry of Science,ICT,MSIT)(RS-2022-00165524)+2 种基金the development of technologies for electroceuticals of National Research Foundation(NRF)funded by the Korean government(MSIT)(RS-2023-00220534)ICT Creative Consilience program through the Institute of Information&Communications Technology Planning&Evaluation(IITP)grant funded by the Korea government(MSIT)(IITP-2024-2020-0-01819)Start up Pioneering in Research and Innovation(SPRINT)through the Commercialization Promotion Agency for R&D Outcomes(COMPA)grant funded by the Korea government(Ministry of Science and ICT)(1711198921).
文摘Soft robots have partially or entirely provided versatile opportunities for issues or roles that cannot be addressed by conventional machine robots,although most studies are limited to designs,controls,or physical/mechanical motions.Here,we present a transformable,reconfigurable robotic platform created by the integration of magnetically responsive soft composite matrices with deformable multifunctional electronics.Magnetic compounds engineered to undergo phase transition at a low temperature can readily achieve reversible magnetization and conduct various changes of motions and shapes.Thin and flexible electronic system designed with mechanical dynamics does not interfere with movements of the soft electronic robot,and the performances of wireless circuit,sensors,and devices are independent of a variety of activities,all of which are verified by theoretical studies.Demonstration of navigations and electronic operations in an artificial track highlights the potential of the integrated soft robot for on-demand,environments-responsive movements/metamorphoses,and optoelectrical detection and stimulation.Further improvements to a miniaturized,sophisticated system with material options enable in situ monitoring and treatment in envisioned areas such as biomedical implants.
