Recently,user recognitionmethods to authenticate personal identity has attracted significant attention especially with increased availability of various internet of things(IoT)services through fifth-generation technol...Recently,user recognitionmethods to authenticate personal identity has attracted significant attention especially with increased availability of various internet of things(IoT)services through fifth-generation technology(5G)based mobile devices.The EMG signals generated inside the body with unique individual characteristics are being studied as a part of nextgeneration user recognition methods.However,there is a limitation when applying EMG signals to user recognition systems as the same operation needs to be repeated while maintaining a constant strength of muscle over time.Hence,it is necessary to conduct research on multidimensional feature transformation that includes changes in frequency features over time.In this paper,we propose a user recognition system that applies EMG signals to the short-time fourier transform(STFT),and converts the signals into EMG spectrogram images while adjusting the time-frequency resolution to extract multidimensional features.The proposed system is composed of a data pre-processing and normalization process,spectrogram image conversion process,and final classification process.The experimental results revealed that the proposed EMG spectrogram image-based user recognition system has a 95.4%accuracy performance,which is 13%higher than the EMGsignal-based system.Such a user recognition accuracy improvement was achieved by using multidimensional features,in the time-frequency domain.展开更多
As fifth generation technology standard(5G)technology develops,the possibility of being exposed to the risk of cyber-attacks that exploits vulnerabilities in the 5G environment is increasing.The existing personal reco...As fifth generation technology standard(5G)technology develops,the possibility of being exposed to the risk of cyber-attacks that exploits vulnerabilities in the 5G environment is increasing.The existing personal recognitionmethod used for granting permission is a password-basedmethod,which causes security problems.Therefore,personal recognition studies using bio-signals are being conducted as a method to access control to devices.Among bio-signal,surface electromyogram(sEMG)can solve the existing personal recognition problem that was unable to the modification of registered information owing to the characteristic changes in its signal according to the performed operation.Furthermore,as an advantage,sEMG can be conveniently measured from arms and legs.This paper proposes a personal recognition method using sEMG,based on a multi-stream convolutional neural network(CNN).The proposed method decomposes sEMG signals into intrinsic mode functions(IMF)using empirical mode decomposition(EMD)and transforms each IMF into a spectrogram.Personal recognition is performed by analyzing time–frequency features from the spectrogram transformed intomulti-streamCNN.The database(DB)adopted in this paper is the Ninapro DB,which is a benchmark EMG DB.The experimental results indicate that the personal recognition performance of the multi-stream CNN using the IMF spectrogram improved by 1.91%,compared with the singlestream CNN using the spectrogram of raw sEMG.展开更多
This study investigated the effects of torrefaction on forest residue(FR)and its subsequent ap-plication as a bulk-loading filler in polylactic acid(PLA)composites.Torrefaction enhanced the chemical properties of FR,i...This study investigated the effects of torrefaction on forest residue(FR)and its subsequent ap-plication as a bulk-loading filler in polylactic acid(PLA)composites.Torrefaction enhanced the chemical properties of FR,improving its compatibility with PLA,and the crystallinity increased from 24.9%to 42.5%.The process also improved the hydrophobicity of PLA/biomass composites,as demonstrated by the water contact angle of 76.1°,closely matching that of neat PLA(76.4°).With the introduction of 20%modified biomass properties after torrefaction treatment,the tensile strength of PLA/biomass composite increased from 58.7 to 62.3 MPa.Additionally,the addition of torrefied forest residue(TFR)accelerated biodegradation by increasing the onset of degrada-tion and inhibiting crystallization.After 90 d,the biodegradability of PLA/biomass composites reached 94.9%,which had a 6.9%increase compared to the neat PLA(88.8%).Overall,this study highlights the potential of torrefaction in enhancing both the physical properties and biodegrad-ability of PLA-based composites,contributing to a more sustainable approach to reducing plastic pollution.展开更多
Three-dimensional(3D)stem cell culture systems have attracted considerable attention as a way to better mimic the complex interactions between individual cells and the extracellular matrix(ECM)that occur in vivo.Moreo...Three-dimensional(3D)stem cell culture systems have attracted considerable attention as a way to better mimic the complex interactions between individual cells and the extracellular matrix(ECM)that occur in vivo.Moreover,3D cell culture systems have unique properties that help guide specific functions,growth,and processes of stem cells(e.g.,embryogenesis,morphogenesis,and organogenesis).Thus,3D stem cell culture systems that mimic in vivo environments enable basic research about various tissues and organs.In this review,we focus on the advanced therapeutic applications of stem cell-based 3D culture systems generated using different engineering techniques.Specifically,we summarize the historical advancements of 3D cell culture systems and discuss the therapeutic applications of stem cell-based spheroids and organoids,including engineering techniques for tissue repair and regeneration.展开更多
Hydroxyapatite(HA)is a representative substance that induces bone regeneration.Our research team extracted nanohydroxyapatite(EH)from natural resources,especially equine bones,and developed it as a molecular biologica...Hydroxyapatite(HA)is a representative substance that induces bone regeneration.Our research team extracted nanohydroxyapatite(EH)from natural resources,especially equine bones,and developed it as a molecular biological tool.Polyethylenimine(PEI)was used to coat the EH to develop a gene carrier.To verify that PEI is well coated in the EH,we first observed the morphology and dispersity of PEI-coated EH(pEH)by electron microscopy.The pEH particles were well distributed,while only the EH particles were not distributed and aggregated.Then,the existence of nitrogen elements of PEI on the surface of the pEH was confirmed by EDS,calcium concentration measurement and fourier transform infrared spectroscopy(FT-IR).Additionally,the pEH was confirmed to have a more positive charge than the 25 kD PEI by comparing the zeta potentials.As a result of pGL3 transfection,pEH was better able to transport genes to cells than 25 kD PEI.After verification as a gene carrier for pEH,we induced osteogenic differentiation of DPSCs by loading the BMP-2 gene in pEH(BMP-2/pEH)and delivering it to the cells.As a result,it was confirmed that osteogenic differentiation was promoted by showing that the expression of osteopontin(OPN),osteocalcin(OCN),and runt-related transcription factor 2(RUNX2)was significantly increased in the group treated with BMP-2/pEH.In conclusion,we have not only developed a novel nonviral gene carrier that is better performing and less toxic than 25 kD PEI by modifying natural HA(the agricultural byproduct)but also proved that bone differentiation can be effectively promoted by delivering BMP-2 with pEH to stem cells.展开更多
Dysfunctional blood vessels are implicated in various diseases,including cardiovascular diseases,neurodegenerative diseases,and cancer.Several studies have attempted to prevent and treat vascular diseases and understa...Dysfunctional blood vessels are implicated in various diseases,including cardiovascular diseases,neurodegenerative diseases,and cancer.Several studies have attempted to prevent and treat vascular diseases and understand interactions between these diseases and blood vessels across different organs and tissues.Initial studies were conducted using 2-dimensional(2D)in vitro and animal models.However,these models have difficulties in mimicking the 3D microenvironment in human,simulating kinetics related to cell activities,and replicating human pathophysiology;in addition,3D models involve remarkably high costs.Thus,in vitro bioengineered models(BMs)have recently gained attention.BMs created through biofabrication based on tissue engineering and regenerative medicine are breakthrough models that can overcome limitations of 2D and animal models.They can also simulate the natural microenvironment in a patient-and target-specific manner.In this review,we will introduce 3D bioprinting methods for fabricating bioengineered blood vessel models,which can serve as the basis for treating and preventing various vascular diseases.Additionally,we will describe possible advancements from tubular to vascular models.Last,we will discuss specific applications,limitations,and future perspectives of fabricated BMs.展开更多
Microscale and nanoscale cilia are ubiquitous in natural systems where they serve diverse biological functions.Bioinspired artificial magnetic cilia have emerged as a highly promising technology with vast potential ap...Microscale and nanoscale cilia are ubiquitous in natural systems where they serve diverse biological functions.Bioinspired artificial magnetic cilia have emerged as a highly promising technology with vast potential applications,ranging from soft robotics to highly precise sensors.In this review,we comprehensively discuss the roles of cilia in nature and the various types of magnetic particles utilized in magnetic cilia;additionally,we explore the top-down and bottom-up fabrication techniques employed for their production.Furthermore,we examine the various applications of magnetic cilia,including their use in soft robotics,droplet and particle control systems,fluidics,optical devices,and sensors.Finally,we present our conclusions and the future outlook for magnetic cilia research and development,including the challenges that need to be overcome and the potential for further integration with emerging technologies.展开更多
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.2017R1A6A1A03015496)the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.NRF-2021R1A2C1014033).
文摘Recently,user recognitionmethods to authenticate personal identity has attracted significant attention especially with increased availability of various internet of things(IoT)services through fifth-generation technology(5G)based mobile devices.The EMG signals generated inside the body with unique individual characteristics are being studied as a part of nextgeneration user recognition methods.However,there is a limitation when applying EMG signals to user recognition systems as the same operation needs to be repeated while maintaining a constant strength of muscle over time.Hence,it is necessary to conduct research on multidimensional feature transformation that includes changes in frequency features over time.In this paper,we propose a user recognition system that applies EMG signals to the short-time fourier transform(STFT),and converts the signals into EMG spectrogram images while adjusting the time-frequency resolution to extract multidimensional features.The proposed system is composed of a data pre-processing and normalization process,spectrogram image conversion process,and final classification process.The experimental results revealed that the proposed EMG spectrogram image-based user recognition system has a 95.4%accuracy performance,which is 13%higher than the EMGsignal-based system.Such a user recognition accuracy improvement was achieved by using multidimensional features,in the time-frequency domain.
基金This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.2017R1A6A1A03015496)the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.NRF-2021R1A2C1014033).
文摘As fifth generation technology standard(5G)technology develops,the possibility of being exposed to the risk of cyber-attacks that exploits vulnerabilities in the 5G environment is increasing.The existing personal recognitionmethod used for granting permission is a password-basedmethod,which causes security problems.Therefore,personal recognition studies using bio-signals are being conducted as a method to access control to devices.Among bio-signal,surface electromyogram(sEMG)can solve the existing personal recognition problem that was unable to the modification of registered information owing to the characteristic changes in its signal according to the performed operation.Furthermore,as an advantage,sEMG can be conveniently measured from arms and legs.This paper proposes a personal recognition method using sEMG,based on a multi-stream convolutional neural network(CNN).The proposed method decomposes sEMG signals into intrinsic mode functions(IMF)using empirical mode decomposition(EMD)and transforms each IMF into a spectrogram.Personal recognition is performed by analyzing time–frequency features from the spectrogram transformed intomulti-streamCNN.The database(DB)adopted in this paper is the Ninapro DB,which is a benchmark EMG DB.The experimental results indicate that the personal recognition performance of the multi-stream CNN using the IMF spectrogram improved by 1.91%,compared with the singlestream CNN using the spectrogram of raw sEMG.
基金supported by the Korea Research Institute of Chemical Technology(KRICT)Project(No.KS2442-10)the R&D Program(No.20017973)of the Ministry of Trade,Industry,and Energy(MOTIE/KEIT).
文摘This study investigated the effects of torrefaction on forest residue(FR)and its subsequent ap-plication as a bulk-loading filler in polylactic acid(PLA)composites.Torrefaction enhanced the chemical properties of FR,improving its compatibility with PLA,and the crystallinity increased from 24.9%to 42.5%.The process also improved the hydrophobicity of PLA/biomass composites,as demonstrated by the water contact angle of 76.1°,closely matching that of neat PLA(76.4°).With the introduction of 20%modified biomass properties after torrefaction treatment,the tensile strength of PLA/biomass composite increased from 58.7 to 62.3 MPa.Additionally,the addition of torrefied forest residue(TFR)accelerated biodegradation by increasing the onset of degrada-tion and inhibiting crystallization.After 90 d,the biodegradability of PLA/biomass composites reached 94.9%,which had a 6.9%increase compared to the neat PLA(88.8%).Overall,this study highlights the potential of torrefaction in enhancing both the physical properties and biodegrad-ability of PLA-based composites,contributing to a more sustainable approach to reducing plastic pollution.
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Korean government(NRF-2021R1A4A3025206,NRF-2019M3A9H1103737,NRF-2021M3E5E7026407,NRF-2019R1I1A3A0106345).
文摘Three-dimensional(3D)stem cell culture systems have attracted considerable attention as a way to better mimic the complex interactions between individual cells and the extracellular matrix(ECM)that occur in vivo.Moreover,3D cell culture systems have unique properties that help guide specific functions,growth,and processes of stem cells(e.g.,embryogenesis,morphogenesis,and organogenesis).Thus,3D stem cell culture systems that mimic in vivo environments enable basic research about various tissues and organs.In this review,we focus on the advanced therapeutic applications of stem cell-based 3D culture systems generated using different engineering techniques.Specifically,we summarize the historical advancements of 3D cell culture systems and discuss the therapeutic applications of stem cell-based spheroids and organoids,including engineering techniques for tissue repair and regeneration.
基金This study was supported by Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Science,ICT&Future Planning(NRF-2020R1F1A1067439,NRF-2020R1I1A1A01068262)the Korea Institute of Energy Technology Evaluation and Planning(KETEP)and the Ministry of Trade,Industry&Energy(MOTIE)of the Republic of Korea(20194210100230).
文摘Hydroxyapatite(HA)is a representative substance that induces bone regeneration.Our research team extracted nanohydroxyapatite(EH)from natural resources,especially equine bones,and developed it as a molecular biological tool.Polyethylenimine(PEI)was used to coat the EH to develop a gene carrier.To verify that PEI is well coated in the EH,we first observed the morphology and dispersity of PEI-coated EH(pEH)by electron microscopy.The pEH particles were well distributed,while only the EH particles were not distributed and aggregated.Then,the existence of nitrogen elements of PEI on the surface of the pEH was confirmed by EDS,calcium concentration measurement and fourier transform infrared spectroscopy(FT-IR).Additionally,the pEH was confirmed to have a more positive charge than the 25 kD PEI by comparing the zeta potentials.As a result of pGL3 transfection,pEH was better able to transport genes to cells than 25 kD PEI.After verification as a gene carrier for pEH,we induced osteogenic differentiation of DPSCs by loading the BMP-2 gene in pEH(BMP-2/pEH)and delivering it to the cells.As a result,it was confirmed that osteogenic differentiation was promoted by showing that the expression of osteopontin(OPN),osteocalcin(OCN),and runt-related transcription factor 2(RUNX2)was significantly increased in the group treated with BMP-2/pEH.In conclusion,we have not only developed a novel nonviral gene carrier that is better performing and less toxic than 25 kD PEI by modifying natural HA(the agricultural byproduct)but also proved that bone differentiation can be effectively promoted by delivering BMP-2 with pEH to stem cells.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(no.2020R1A5A8018367)the Technology Innovation Program(or Industrial Strategic Technology Development Program(20015148,Development of Neural/Vascular/Muscular-Specific Peptides-conjugated Bioink and Volumetric Muscle Tissue)funded By the Ministry of Trade,Industry&Energy(MOTIE,Korea).
文摘Dysfunctional blood vessels are implicated in various diseases,including cardiovascular diseases,neurodegenerative diseases,and cancer.Several studies have attempted to prevent and treat vascular diseases and understand interactions between these diseases and blood vessels across different organs and tissues.Initial studies were conducted using 2-dimensional(2D)in vitro and animal models.However,these models have difficulties in mimicking the 3D microenvironment in human,simulating kinetics related to cell activities,and replicating human pathophysiology;in addition,3D models involve remarkably high costs.Thus,in vitro bioengineered models(BMs)have recently gained attention.BMs created through biofabrication based on tissue engineering and regenerative medicine are breakthrough models that can overcome limitations of 2D and animal models.They can also simulate the natural microenvironment in a patient-and target-specific manner.In this review,we will introduce 3D bioprinting methods for fabricating bioengineered blood vessel models,which can serve as the basis for treating and preventing various vascular diseases.Additionally,we will describe possible advancements from tubular to vascular models.Last,we will discuss specific applications,limitations,and future perspectives of fabricated BMs.
基金supported by the National Research Foundation of Korea(NRF)(2021R1A2C3006297,2021R1A4A3025206)the Technology Innovation Program(00144157)funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea).
文摘Microscale and nanoscale cilia are ubiquitous in natural systems where they serve diverse biological functions.Bioinspired artificial magnetic cilia have emerged as a highly promising technology with vast potential applications,ranging from soft robotics to highly precise sensors.In this review,we comprehensively discuss the roles of cilia in nature and the various types of magnetic particles utilized in magnetic cilia;additionally,we explore the top-down and bottom-up fabrication techniques employed for their production.Furthermore,we examine the various applications of magnetic cilia,including their use in soft robotics,droplet and particle control systems,fluidics,optical devices,and sensors.Finally,we present our conclusions and the future outlook for magnetic cilia research and development,including the challenges that need to be overcome and the potential for further integration with emerging technologies.
