• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.64-64
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• 2008

연속공정이 가능한 Roll to Roll sputter system을 이용하여 플렉시블 indium tin oxide(ITO) 투명전극을 PET(polyethlyene terephthalate) 기판위에 성막하였다. 연속 성막공정을 위해 Roll to Roll sputter system에서의 unwinder roller와 rewinder roller를 이용한 servomotor의 rolling으로 기판의 움직임이 완벽히 제어되었으며, 외부 응력으로 부터의 안정성 및 성막 공정 시의 PET 기판의 열적 변형을 최소화하기 위한 접촉식 냉각방식의 cooling system을 main drum으로 사용하였다. 또한 고분자 기판과 투명전극 사이의 adhesion을 향상시키기 위한 전처리 공정으로 gridless linear ion beam source를 pretreatment system으로 구축하였다. 이렇게 제작된 Roll to Roll sputter system을 이용하여 PET 기판위에 연속공정을 통해 ITO 투명전극을 성막하였다. 성막된 플렉시블 ITO/PET 투명전극은 XRD, HREM, SEM 분석을 통하여 main drum의 cooling에 의해 완전한 비정질 구조를 나타내었음을 확인할 수 있었으며, 비록 Roll to Roll sputter system을 통하여 상온에서 성막 되었음에도 불구하고 최적화 된 조건에서 가시광선 영역 83.46 %의 높은 광투과도 값과 47.4 Ohm/square의 비교적 낮은 먼저항 값을 얻을 수 있었다. 또한 Bending test 결과를 통하여 ion source의 전처리 공정으로 굽힘/평의 반복적 응력에 따른 전기적 특성 열화를 최소화 할 수 있음을 보였다. 최적화된 플렉시블 투명전극을 이용하여 P3HT:PCBM 기반의 플렉시블 유기태양전지를 제작하였으며, 제작된 유기태양전지로부터 1.88%의 power conversion efficiency (PCE)을 확보함으로써 플렉시블 유기태양전지 제작을 위한 ITO/PET 투명전극 성막 공법으로써 Roll to Roll sputter system의 적용가능성을 확인할 수 있었다.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.5
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• pp.365-373
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• 2021

In this study, evaporation of LN2 non-spreading pool on concrete plate was dealt with experimentally. The thermophysical properties of concrete, which is a composite material, were obtained by minimizing the difference between the numerical analysis results obtained from the assumed properties and the results from experiments. The thermal energy required for evaporation of the liquid pool is supplied from the concrete plate and the wall of the container. As a result of the measurement, the thermal energy flowing in from the wall was negligible compared to the one supplied from the concrete plate. It was found that the measured evaporation rate of the liquid pool by the heat energy supplied through the concrete plate agrees well with the PTC model except for the initial section of the experiment. The validity of the semi-infinite assumption and the one-dimensional assumption, which are the main conditions of the PTC model, was also verified through experiments. The evaporation rate model in the non-spreading pool discussed in this study can provide a basic frame for the one in the spreading pool, which is a meaningful result considering that the spreading pool is very realistic compared to the non-spreading pool.

• Journal of the Korean Geotechnical Society
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• v.38 no.9
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• pp.45-52
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• 2022

Because discontinuity in the rock mass and contact of soil-structure interaction exhibits coupled thermal-hydromechanical (THM) behavior, it is necessary to develop an interface element based on the full governing equations. In this study, we derive force equilibrium, fluid continuity, and energy equilibrium equations for the interface element. Additionally, we present a stiffness matrix of the elastoplastic mechanical model for the interface element. The developed interface element uses six nodes for displacement and four nodes for water pressure and temperature in a two-dimensional analysis. The fully coupled THM analysis for fluid injection into a fault can model the complicated evolution of injection pressure due to decreasing effective stress in the fault and thermal contraction of the surrounding rock mass. However, the result of hydromechanical analysis ignoring thermal phenomena overestimates hydromechanical variables.