근전도에 의한 계단 상하행시 근 피로 비교

민병찬(Byungchan Min),김전환(JunHwan Kim),전광진(KwangJin Jeon),이동형(DongHyung Lee),김진수(JinSoo Kim) 한국산업경영시스템학회 2006 한국산업경영시스템학회 학술대회 Vol.2006 No.춘계

본 연구는 젊은층과 고령층을 대상으로 계단 상하행시 하지근군의 근전도(EMG;Electromyogram)를 측정하여 발휘근육부위와 근피로 정도와의 관계를 파악하기 위해 근전도 amplitude 분석을 실시하여, 비교하였다. 피험자는 젊은층과 고령층 각각 20명이었으며, 하지근 8부위(전경골근, 내측광근, 외측광근, 대퇴직근, 반건양근, 대퇴이두근, 내비복근, 외비복근)에 전극을 부착하여 계단 상하행 전후의 근전도를 측정하였다. 그 결과 젊은층은 계단 상하 보행 후 모든 측정 부위의 근전도 amplitude가 커졌으며, 고령층도 전경골근과 대퇴직근을 제외한 근육 6부위에서 근전도 amplitude가 커졌다. 또한 젊은층과 고령층의 amplitude 분석 값을 비교해 보면, 대퇴이두근과 내비복근을 제외한 모든 근육부위에서, 젊은층의 amplitude 값이 고령층에 비해 계단 상하 보행 전후 변화가 더 크게 나타났으며 특히 전경골근은 통계적 유의차가 인정되었다(p<0.05). 이와 같이 젊은층에 비해 고령층은 근육량이 적으므로 amplitude의 변화가 작은데, 노인들을 위한 제품 또는 환경 설계시 노인 근전도의 특성을 고려하여 측정하고 분석해야 할 것이다.

Toward New Fuel Cell Support Materials: A Theoretical and Experimental Study of Nitrogen-Doped Graphene

Seo, Min Ho,Choi, Sung Mook,Lim, Eun Ja,Kwon, In Hye,Seo, Joon Kyo,Noh, Seung Hyo,Kim, Won Bae,Han, Byungchan Wiley (John WileySons) 2014 CHEM SUS CHEM Vol.7 No.9

<P>Nano-scale Pt particles are often reported to be more electrochemically active and stable in a fuel cell if properly displaced on support materials; however, the factors that affect their activity and stability are not well understood. We applied first-principles calculations and experimental measurements to well-defined model systems of N-doped graphene supports (N-GNS) to reveal the fundamental mechanisms that control the catalytic properties and structural integrity of nano-scale Pt particles. DFT calculations predict thermodynamic and electrochemical interactions between N-GNS and Pt nanoparticles in the methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR). Moreover, the dissolution potentials of the Pt nanoparticles supported on GNS and N-GNS catalysts are calculated under acidic conditions. Our results provide insight into the design of new support materials for enhanced catalytic efficiency and long-term stability.</P>

Bifunctionally active and durable hierarchically porous transition metal-based hybrid electrocatalyst for rechargeable metal-air batteries

Seo, Min Ho,Park, Moon Gyu,Lee, Dong Un,Wang, Xiaolei,Ahn, Wook,Noh, Seung Hyo,Choi, Sung Mook,Cano, Zachary P.,Han, Byungchan,Chen, Zhongwei Elsevier 2018 Applied catalysis. B, Environmental Vol.239 No.-

<P><B>Abstract</B></P> <P>In this work, we show an effective strategy combining experimental and computational methods to explore and clarify rational design approaches utilizing transition metals for enhanced electrocatalysis of oxygen reactions. We report a bifunctional electrocatalyst synthesized by a chemical deposition of palladium (Pd) nanoparticles on three-dimensionally ordered mesoporous cobalt oxide (Pd@3DOM-Co<SUB>3</SUB>O<SUB>4</SUB>) demonstrating extreme stability and activity towards electrocatalytic oxygen reduction and evolution reactions (ORR and OER). Pd@3DOM-Co<SUB>3</SUB>O<SUB>4</SUB> exhibits a significantly positive-shifted ORR half-wave potential of 0.88 V (vs. RHE) and a higher OER current density of 41.3 mA cm<SUP>−2</SUP> measured at 2.0 V (vs. RHE) relative to non-deposited 3DOM-Co<SUB>3</SUB>O<SUB>4</SUB>. Moreover, in terms of durability, Pd@3DOM-Co<SUB>3</SUB>O<SUB>4</SUB> demonstrates a negligible half-wave potential loss with 99.5% retention during ORR and a high current density retention of 96.4% during OER after 1000 cycles of accelerated degradation testing (ADT). <I>Ab-initio</I> computational simulation of the oxygen reactions reveals that the modification of the electronic structure by combining Pd and Co<SUB>3</SUB>O<SUB>4</SUB> lowers the Pd d-band center and enhances the electron abundance at the Fermi level, resulting in improved kinetics and conductivity. Furthermore, it is elucidated that the enhanced electrochemical stability is attributed to an elevated carbon corrosion potential (<I>U<SUB>corr,C</SUB> </I>) for the Pd@3DOM-Co<SUB>3</SUB>O<SUB>4</SUB> surface and an increased dissolution potential (U<SUB>diss</SUB>) of Pd nanoparticles. Meanwhile, synergistic improvements in the bifunctional activity resulting from the combination of Pd and 3DOM-Co<SUB>3</SUB>O<SUB>4</SUB> were confirmed by both electrochemical and physical characterization methods, which highlights the practical viability of Pd@3DOM-Co<SUB>3</SUB>O<SUB>4</SUB> as an efficient bifunctional catalyst for rechargeable metal-air batteries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Strategy for rational design of transition metal-based bifunctional electrocatalyst. </LI> <LI> Synergistic combination of Pd and 3DOM Co<SUB>3</SUB>O<SUB>4</SUB> for enhanced activity and durability. </LI> <LI> Doped-Pd on 3DOM Co<SUB>3</SUB>O<SUB>4</SUB> leads to electron abundance at the Fermi level. </LI> <LI> Low carbon corrosion and bulk–like dissolution tendency of doped-Pd on 3DOM Co<SUB>3</SUB>O<SUB>4</SUB>. </LI> <LI> 500 h of Zn-air battery operation with improved charge-discharge performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

First principles computational study on the electrochemical stability of Pt-Co nanocatalysts

Noh, Seung Hyo,Seo, Min Ho,Seo, Joon Kyo,Fischer, Peter,Han, Byungchan The Royal Society of Chemistry 2013 Nanoscale Vol.5 No.18

<P>Using density functional theory (DFT) calculations, we identify the thermodynamically stable configurations of Pt-Co alloy nanoparticles of varying Co compositions and particle sizes. Our results indicate that the most thermodynamically stable structure is a shell-by-shell configuration where the Pt atom only shell and the Co only shell alternately stack and the outermost shell consists of a Pt skin layer. DFT calculations show that the structure has substantially higher dissolution potential of the outermost Pt shell compared with pure Pt nanoparticles of approximately the same size. Furthermore, our DFT calculations also propose that the shell-by-shell structure shows much better oxygen reduction reaction (ORR) activity than conventional bulk or nanoparticles of pure Pt. These novel catalyst properties can be changed when the surfaces are adsorbed with oxygen atoms via selective segregation followed by the electrochemical dissolution of the alloyed Co atoms. However, these phenomena are thermodynamically not plausible if the chemical potentials of oxygen are controlled below a certain level. Therefore, we propose that the shell-by-shell structures are promising candidates for highly functional catalysts in fuel cell applications.</P>

Towards a comprehensive understanding of FeCo coated with N-doped carbon as a stable bi-functional catalyst in acidic media

Noh, Seung Hyo,Seo, Min Ho,Kang, Joonhee,Okajima, Takeyoshi,Han, Byungchan,Ohsaka, Takeo Nature Publishing Group 2016 NPG Asia Materials Vol.8 No.-

<P>The identification and development of efficient catalysts made of non-precious materials for oxygen reduction reaction (ORR) are essential for the successful operation of a wide range of energy devices. This study provides evidence that earth-abundant nanoparticles of transition metals encapsulated in a nitrogen-doped carbon shell (M@N-C, M = Fe, Co, Ni, Cu or Fe alloys) are promising catalysts in acidic solutions. By density functional theory calculations and experimental validations, we quantitatively propose a method of tuning the ORR activity of M@N-C by controlling the nitrogen-doping level, the thickness of the N-C shells and binary alloying. FeCo@N-C/KB was chosen as the best ORR catalyst because of its onset and half-wave potentials of 0.92 and 0.74 V vs a reversible hydrogen electrode (RHE), respectively, and its excellent durability. Furthermore, FeCo@N-C/KB possesses a high activity for the hydrogen evolution reaction (HER; -0.24 V vs RHE at -10 mA cm(-2)), thus demonstrating that it is a good bi-functional ORR and HER catalyst in acidic media.</P>

자동차 그래픽 시뮬레이터에서 동시자극에 대한 페퍼민트 향의 효과

김규범(Kyubeom Kim),민병찬(Byungchan Min) 인문사회과학기술융합학회 2019 예술인문사회융합멀티미디어논문지 Vol.9 No.5

본 연구는 차량 운전자가 동시자극으로 인한 환경에 처했을 때, 향 자극이 스트레스를 경감시키는 효과가 있는지 생체신호 측정을 통해 규명하고자 한다. 피험자 12명을 대상으로 생체신호의 주파수분석을 위해 뇌파는 α파와 β파로 구분하였으며, 심전도는 LF, HF대역별로 구분하여 중추신경계 및 교감신경계 활성도를 통해 안정, 각성상태를 확인하였다. 자동차 그래픽 시뮬레이터를 통해 운전 환경을 조성하였으며, 판단능력을 검사하는 Judgment Test Simulation을 실시하였다. 그 결과 뇌파의 경우, 주행만 실시한 대조군에 비해 동시자극을 제시한 실험군의 α파가 감소하였다(p<0.05). 향 자극을 제시하였을 경우, 대조군에 비해 α파가 감소하였으며 β파 역시 감소하였다(p<0.05). 심전도의 경우, 집단 간 유의한 차이가 나타나지 않았지만(p>0.05), 교감신경계가 활성화되는 경향을 보였다. 대조군과 실험군의 비교결과를 통해 동시자극이 스트레스를 유발하였음을 확인할 수 있었고, 향 자극을 통해 생리적으로 각성상태를 확인할 수 있었다. This study is aimed to specify whether or not fragrance stimuli have an effect to reduce the stress when vehicle drivers are in the environment of the simultaneous stimuli through bio-signal measurement. In order to analyze the frequency of the biological signal for 12 subjects, a brain wave was divided into α-wave and β- wave, and ECG is divided by LF and HF bands, and the state of stability and awakening was identified through the activity of the central nervous system and sympathetic nervous system. The driving environment was created through a vehicle graphic simulator, and Judgment Test Simulation which examines judgment ability was conducted. As a result, for brain wave, the α- wave of the experimental group where the simultaneous stimuli were presented decreased(p<0.05), compared to the control group where only a drive was conducted, When fragrance stimuli were presented, α-wave decreased and β- wave also decreased(p<0.05), compared to the control group. For ECG, there was no significant difference between groups(p>0.05), however, there was a tendency that sympathetic nervous system got activated. Through the results of the comparison between the control group and the experimental group, it could be identified that the simultaneous stimuli induced the stress, and through fragrance stimuli, the state of awakening could be identified physiologically.

현장계측을 통한 지하증축공사 중 가설구조물의 거동 사례연구

김의석(Uiseok Kim),민병찬(Byungchan Min),강민규(Minkyu Kang),김동관(Dongkwan Kim),최항석(Hangseok Choi) 한국지반환경공학회 2020 한국지반환경공학회논문집 Vol.21 No.8

노후시설물의 지하공간 확장공사 시 공사 중 소음 및 진동 문제 뿐만 아니라 기존 주민의 임시 거주공간 확보가 필요하고, 상업용, 공업용, 사회용 등의 시설물의 경우에는 시설물 이용의 중단에 따른 피해가 예상되므로, 지하증축 공사 중 소음 및 진동을 최소화하여 공사 중에도 기존 시설물의 이용을 가능하게 하는 기술이 필요하다. 따라서 본 연구에서는 가설구조물의 안정성 문제와 공사 중 발생되는 소음진동 문제를 효과적으로 해결하여 지하증축 공사 중 시설물을 이용하면서 진행한 공사현장의 시공단계별 계측결과로 가설구조물과 주변지반의 거동을 분석하여 국내 현실에 적합한 지하증축공사 모델을 제시하였다. 시공 시 발생되는 문제를 해결하기 위해 초기 굴착 후 슬라브 선타설공법을 적용한 현장의 계측결과(건물경사계, 균열측정계, 구조물경사계, 지표침하계)를 확인한 결과 건물경사계와 구조물경사계는 슬라브 선타설후 변위가 감소하거나 수렴하는 경향을 확인할 수 있었으며, 균열측정계와 지표침하계는 관리기준 이내의 안정적인 모습을 확인할 수 있었다. 이 결과로 볼 때, 지하증축 공사 시 지하층 슬라브를 선타설하는 것은 공사 중 발생하는 소음․진동의 문제를 해결해주는 것 뿐만 아니라 지하증축 공사 시 가설구조물의 안정성을 확보하는데 큰 역할하고 있는 것을 확인할 수 있었다. During the construction of underground space expansion of old facilities, it is necessary to secure temporary residence space for existing residents as well as noise and vibration issues during construction, and in the case of commercial, industrial, and social use, damage is expected from suspension of the use of facilities. There is a need for a technology that minimizes noise and vibration during underground expansion, enabling the use of existing facilities even during construction. In this study, a practical underground extension model is proposed by analyzing the behavior of the temporary structure and the surrounding ground as a result of measurement at each construction stage for a actual construction site. In order to solve the problems that occurred during construction, the basement slabs were placed in advance after the initial excavation. The measurement results (building inclinometer, crack measurement system, structure inclinometer and surface settlement meter) at the site were reviewed to analyze the behavior of the temporary structure and surrounding ground. As a result, it was confirmed that the inclinometer of the building and the structural inclinometer showed a tendency that the displacement after the slab line was placed was reduced or converged. The placement of basement slabs during underground extension not only relived the noise and vibration problems during construction, but also secured the stability of structures.

부정적 이미지 자극과 청각자극의 동시자극으로 유발된 자율신경계의 반응 연구

( Sanghyeok Seo ),( Jinkyu Kang ),( Byungchan Min ) 한국감성과학회 2013 추계학술대회 Vol.2013 No.-

Study of Adaptive Assisting Effect of Auditory-visual Alert for Elderly Drivers using Physiological Signals

Seunghee Hong,Seiya Harada,Kazuaki Onoue,Byungchan Min,Keisuke Suzuki,Shun'ichi Doi 대한인간공학회 2012 대한인간공학회 학술대회논문집 Vol.2012 No.5

A major cause of traffic accidents has been found in the human factors involved in driver's awareness during driving, and the effect of alarm was reported as the increase of awareness and the improving effect for property of perception, cognition and judgment of the driver. The arousal stimulus for driver by auditory-visual alert also affects to the physiological condition and the autonomic nervous system (ANS). Recent developments in multi near-infrared spectroscopy (MNIRS) have enabled the arousal level apparent with brain activity by measurement of hemoglobin concentrations as cerebral blood volume, as well as the ordinary biological signals like heart beats, finger plethysmogram and pulsation waves. In this study, the three kinds of auditory alert as pre-information, sound alert and voice guidance were used for adaptive assisting systems for the elderly driver and the influence of these alerts on the driver's psychosomatic state was examined using driving simulator for 30 minutes driving. Experiment was conducted with the subjects in a driving position as they were partially awakened by auditory-visual alert, repeatedly and measured their biological properties. As the results, after taking the effects of the adaptive assisting alert systems, the effect of arousal and awareness improvement was recognized in the subjects and the activation of cerebral blood volume was observed according to the amount of the stimulus and combination of awareness modal as auditory alert system.

Study on Adaptive Driving Assistant System for the Elderly Driver Considering Individual Characteristics

Seunghee Hong(洪承?),Keisuke Suzuki,Byungchan Min,Shun’ichi Doi 대한인간공학회 2014 대한인간공학회 학술대회논문집 Vol.2014 No.5