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RISS 인기검색어
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- 저자 : 최유송(Yu Song Choi) (검색결과 5 건)
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최유송,정해원,김기열,조성백,Choi, Yu-Song,Cheong, Hae-Won,Kim, Ki-Youl,Cho, Sung-Baek 한국군사과학기술학회 2012 한국군사과학기술학회지 Vol.15 No.2
Thermal batteries have excellent mechanical robustness, reliability, and long shelf life. Due to these characteristics as well as their unique activation mechanism, thermal batteries are widely adopted as military power sources. Li(Si)/$FeS_2$ thermal batteries, which are used mostly in these days, use LiCl-KCl and LiBr-LiCl-LiF as molten salt electrolyte. However, it is known that Li(Si)/$FeS_2$ thermal batteries have high internal resistance. Especially, $FeS_2$ cathode accounts for the greater part of internal resistance in unit cell. Many efforts have been put into to decrease the internal resistance of thermal batteries, which result in the development of new electrode material and new electrode manufacturing processes. But the applications of these new materials and processes are in some cases very expensive and need complicated additional processes. In this study, internal resistance study was conducted by adding carbon black and carbon nano-tube, which has high electron conductivity, into the $FeS_2$ cathode. As a results, it was found that the decrease of internal resistance of $FeS_2$ cathode by the addition of carbon black and carbon nano-tube.
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고온 작동형 전지의 전해질 및 전극내 첨가염 변화에 따른 전기화학적 특성 연구
최유송,하상현,조성백,Choi, Yu-Song,Ha, Sang-Hyun,Cho, Sung-Baek 한국군사과학기술학회 2011 한국군사과학기술학회지 Vol.14 No.4
Thermally activated batteries have good stability, reliability and long shelf life. Due to these characteristics and operational mechanism, thermal batteries are usually applied to military power sources. Especially, Li/$FeS_2$ thermal batteries, which are used mostly in these days, use LiCl-KCl and LiBr-LiCl-LiF as electrolytes. The electrochemistry of thermal batteries have been researched for long time, however, electrochemical study using impedance spectroscopy was not published so much. Through this research, microscopic electrochemical research was investigated with electrochemical impedance spectroscopy(E.I.S). Electrolyte effects on Li/$FeS_2$ thermal battery was researched changing electrolytes, LiCl-KCl and LiBr-LiCl-LiF. Additionally, the salts, which are added to electrolytes, effects on thermal battery were researched. It is expected that the impedance spectroscopy analysis is applicable to not only thermal battery electrochemical study effectively, but also, thermal battery developments.
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열전지의 전기화학적 특성에 미치는 황철석(FeS2) 입자크기의 영향
최유송 ( Yu Song Choi ),유혜련 ( Hye Ryeon Yu ),정해원 ( Hae Won Cheong ),조성백 ( Sung Baek Cho ),이영석 ( Young Seak Lee ) 한국공업화학회 2014 공업화학 Vol.25 No.2
본 연구에서는 열전지용 양극활물질로 사용되는 FeS2 (Pyrite) 분말을 볼밀링법으로 분쇄하여 단위전지를 제작하고, 볼밀 전, 후 입자크기변화가 열전지의 전기화학적 특성에 미치는 영향을 고찰하였다. 450 ℃ 시험결과, 분쇄된 1.46 μm FeS2 분말을 사용한 단위전지가 분쇄 전 98.4 μm의 FeS2 분말을 사용한 단위전지에 비해서 전지용량이 크게 향상되었으며, 내부저항도 감소되었다. 이러한 결과는 볼밀로 인한 비표면적 증가의 영향으로 판단된다. 반면, 500 ℃에서 방전 시 1단계의 Z-phase 반응구간(FeS2 → Li3Fe2S4)에서 1.46 μm 분말을 사용한 단위전지 전압 및 저항특성이 우수하였지만, 2단계의 J-phase 반응(Li3Fe2S4 → LiFe2S4)에서는 볼밀된 1.46 μm 분말을 사용한 전지의 전압이 감소하고, 전지 내부저항도 급격하게 증가하는 경향을 보였다. 이러한 현상은 500 ℃ 방전시 미분화된 FeS2가 Z-phase 영역에서 방전반응과 동시에 열분해에 의한 자가방전(FeS2 → FeS1.14 (pyrrhotite))이 일어나 볼밀 전 조대한(coarsen) FeS2 분말에 비해 용량이 감소하고 내부 저항도 증가되기 때문으로 사료된다. In this study, effects of pyrite (FeS2) particle sizes on the electrochemical characteristics of thermal batteries are investigated using unit cells made of pulverized pyrite by ball-milling. At 450 ℃ unit cell discharge test, the electrochemical capacity of 1.46 μm pyrite-cell largely increases compared to 98.4 μm pyrite-cell, and their internal resistances also decrease. These results are attributed to the increase in the active reaction area of pyrite by ball milling. However, at 500 ℃ unit cell discharge test, a 1.46 μm pyrite cell shows lower internal resistance than that of 98.4 μm pyrite cell only at Z-phase region (FeS2 → Li3Fe2S4). After that, a 1.46 μm pyrite cell shows a decrease in the cell voltage and an rapid increase of the internal resistance in J-phase region (Li3Fe2S4 → LiFe2S4) is observed compared to those of 98.4 μm pyrite cell. It can be concluded that at the higher temperature, the thermally unstable pulverized pyrite is decomposed thermally as well as self discharged, simulta-neously, which causes the higher resistance and lower capacity at 500 ℃ in J-phase than that of 98.4 μm pyrite cell.
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환기현상의 수치적 해석을 위한 난류모델의 영향에 관한 연구
김철환(Chul Hwan Kim),유근종(Geun Jong Yoo),최훈기(Hoon Ki Choi),공영경(Yeong Kyung Kong),최유송(Yu Song Choi) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
Ventilation is required to keep proper working condition inside building enclosure. Ventilation effect can be evaluated through numerical analysis before its implementation. Usual method of ventilation is mixed convection. Numerical analysis is performed with 3 different turbulence models of k-ε model, RNG k-ε model and Reynolds stress model. Also, 3 different wall functions are utilized in the analysis. Comparison of prediction results and experimental data show general agreement each other. The prediction performance with different turbulence models are shown similar each other.
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