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리튬이온배터리를 위한 음극재의 전기화학적 특성에 따른 평형 전위와 부피 변화에 대한 연구
지상구(Sang-Gu Ji),Nurzhan Umirov,김향연(Hyang-Yeon Kim),김성수(Sung-Soo Kim) 한국전지학회 2021 한국전지학회지 Vol.1 No.1
실리콘과 상용화 흑연 전극의 전기화학적 평가를 통하여 수명 특성을 확인하였다. 사이클 후에 전압 거동과 준 평형 전위(Quasi-Open circuit voltage) 측정을 진행하여, 용량 열화와 평형 전위의 상관성을 분석하였다. 실리콘과 흑연의 연속 충전(Trickle charge)으로 평형 전위(Open circuit voltage)와 부피 변화(In-situ dilation)가 일어나는 것으로 흑연 대비 실리콘의 팽창이 물질 상태 변화 및 입자 파괴로 인하여 전극 성능의 저하로 이어지는 것을 확인할 수 있었다. Commercial graphite and silicon-based anode materials were comparatively analyzed to understand their degradation mechanism by means of quasi open-circuit voltage (quasi-OCV) tracking upon cycling. Moreover, we introduce a novel electrode degradation tracking technique by trickle charge of electrodes and measure of OCV and in-situ dilation. Hence, commercial graphite possesses stable trickle charge OCV suggesting same material state at charged states. Unlike, continuous change of trickle charge OCV and dilation of silicon-based anode indicate ever-changing material state, fracture of particles, advent of new active phases, leading to irreversible electrode degradation.
지상구(Sang Gu Ji),최창혁(Chang Hyuck Choi) 한국세라믹학회 2020 세라미스트 Vol.23 No.4
Investigation of the targeted electrode in (photo)electrochemical system is typically carried out in a conventional three-electrode system, which is comprised of working, counter, and reference electrodes in a batch-type electrochemical reactor. Depending on the nature of targeted electrode, appropriate use of the counter electrode, which balances the charge transfers from the working electrode, is recommended to avoid any contaminations. However, this analytical basic has been often ignored, producing non-negligible but incognizant artifact in experimental results and finally leading to a failure in their correct interpretations. Herein, we highlight the importance of selection on counter electrode and cell configuration for achieving the best practice of (photo)electrochemical investigations with two different model systems, i.e., photoelectrochemical hydrogen evolution reaction (HER) on a p-Si photocathode and electrochemical oxygen reduction reaction (ORR) on a polycrystalline platinum. From the model studies, we further discuss about the suitable electrochemical systems for accurate measurements of (photo)electrode materials.
뒤시엔느 근이영양증 환자에게 기계적 기침보조기법 적용의 임상적 의의
김명권 ( Myung Kwon Kim ),지상구 ( Sang Gu Ji ) 대한물리의학회 2011 대한물리의학회지 Vol.6 No.4
Purpose:The aim of this study was to clarify the lung capacity, maximal insufflation capacity, and peak cough flow when a mechanical insufflation-exsufflation(MIE) method was used to increase Duchenne muscular dystrophy patients` lung function. Methods:The subjects of the study were 21 patients with Duchenne muscular dystrophy. They were randomly selected from patients within the boundaries of the selection criteria, and divided into two groups; The subject group (n=11) used the mechanical insufflation-exsufflation method with traditional therapeutic exercise. The control group (n=10) used only traditional therapeutic exercise. Results:The results indicated that maximal insufflation capacity, unassisted peak cough flow and assisted peak cough flow significantly increased in the subject group(p<05). By contrast, in the control group, the results didn`t indicate the significant differences from the variable. There were significant differences in maximal insufflation capacity and assisted peak cough flow between the subject group and the control group before and after the application of the mechanical insufflation-exsufflation method. Conclusion:A mechanical insufflation-exsufflation method has positive effects on the improvements of cough functions and that of pulmonary functions such as lung volume, lung elasticity in patients with Duchenne muscular dystrophy.