• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.101.3-101.3
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• 2010

Glass frit은 실리콘 태양전지의 Ag/Si contact을 위해 필수적이다. 태양전지의 고효율 특성 구현 때문에, Contact resistance(Rc)가 우수한 Pb-frit의 사용이 불가피한 상황이다. 본 연구는 기존의 Pb계를 무연화함과 동시에 동등수준의 효율을 목표로 하였다. Ag 분말 size 및 glass frit의 열적 거동 특성이 SiNx 코팅층 침투와 Ag re-crystallites에 미치는 영향에 대해 평가하였다. 6 inch 다결정 실리콘 웨이퍼를 사용하였으며, softening temperture(Sp)별로 4종의 Bi계 glass frit을 제조 하였고, 분말 size가 다른 3종의 Ag powder를 선정하였다. Glass frit Sp가 $460^{\circ}C$ 이상의 경우에는 효율이 10% 미만이였으나 Sp $460^{\circ}C$ 이하에서는 16% 수준의 효율을 확인할 수 있었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.3
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• pp.22-29
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• 2004

Deformation of the porous media has influence on performance of a proton exchange membrane fuel cell (PEMFC). The stress distributions and deformation of the porous media are major factors for safe and efficient operation in the PEMFC. In this paper, nonlinear contact analysis of air plate and porous media is performed under a working condition to predict the performance characteristics of the air plates. Two kinds of models are suggested for this study. The first porous media model has nonlinear material properties. The second model has nonlinear material properties with contact condition between porous media and air plate. The numerical analysis results of the two models are somewhat different. It is shown that the nonlinear contact analysis is required for the design study of the PEMFC.

• Journal of Aerospace System Engineering
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• v.17 no.1
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• pp.51-58
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• 2023

Hypergolic propellants, which can ignite themselves without an ignition source, are difficult to handle due to their corrosiveness and toxicity. Therefore, it is necessary to develop green hypergolic propellants with little or no toxicity. In this study, basic research on green hypergolic ignition propellants was conducted. With 95% hydrogen peroxide as an oxidizer and CNU_HGFv1 as a fuel, ignition and combustion characteristics of propellants were evaluated through a drop test, an ignition test, and a combustion test. As a result of the drop test, the ignition delay time was 9.7 ms. It was 27 ms in the ignition test, which was fast enough to be used as a propellant. As a result of the combustion test, a combustion efficiency of 95.4~98.1% was achieved at about 11.7 bar. It was confirmed that fast and stable combustion was possible without hard start or combustion instability.

• Composites Research
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• v.36 no.6
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• pp.422-428
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• 2023

The electrical contact resistance between the bipolar plate (BP) and the carbon felt electrode (CFE), which are in contact by the stack clamping pressure, has a great impact on the stack efficiency because of the relatively low clamping pressure of the vanadium redox flow battery (VRFB) stack. In this study, a polyethylene (PE) composite-CFE hybrid bipolar plate structure is developed through a local heat welding process to reduce such contact resistance and improve cell performance. The PE matrix of the carbon fiber composite BP is locally melted to create a direct contact structure between the carbon fibers of CFE and the carbon fibers of BP, thereby reducing the electrical contact resistance. Area specific resistance (ASR) and gas permeability are measured to evaluate the performance of the PE composite-CFE hybrid bipolar plate. In addition, an acid aging test is performed to measure stack reliability. Finally, a VFRB unit cell charge/discharge test is performed to compare and analyze the performance of the developed PE composite-CFE hybrid BP and the conventional BP.

• Applied Chemistry for Engineering
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• v.31 no.3
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• pp.341-345
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• 2020

An in situ regeneration of activated carbon bed using an ozonated water was studied in order for avoiding the carbon loss, contaminant emission and time consuming for discharge-regeneration-repacking in a conventional thermal regeneration process. Using phenol and polyethylene glycol (PEG) as adsorbates, the adsorption breakthrough and in situ regeneration with the ozonated water were repeated. These organics were supposed to degrade by the oxidation reaction of ozone, regenerating the bed for reuse. As the number of regeneration increased, the adsorption capacity for phenol was reduced, but the change was stabilized showing no further reduction after reaching a certain degree of decrement. The reduction of adsorption capacity was due to the increase of pore size resulting in the decrease of specific surface area during ozonation. The adsorption capacity of phenol decreased after the ozonated regeneration because the in-pore adsorption was prevalent for small molecules like phenol. However, PEG did not show such decrease and the adsorption capacity was constantly maintained after several cycles of the ozonated regeneration probably because the external surface adsorption was the major mechanism for large molecules like PEG. Since the reduction in the pore size and specific surface area for small molecules were proportional to the duration of contact time with the ozonated water, careful considerations of the solute size to be removed and controlling the contact time were necessary to enhance the performance of the ozonated in situ regeneration of activated carbon bed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.111-112
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• 2013

• Defense and Technology
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• no.9 s.175
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• pp.26-33
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• 1993

무기체계에는 무기, 인간조작자, 전투환경 및 지원조직을 폭넓게 포함하는데 여기에서 강조되는 인간은 임무성능의 최적화에 핵심적인 요소입니다 인간공학 접촉면(HIS)은 인간공학, 심리학, 생리학, 운영분석, 전자, 컴퓨터 및 체계공학 등의 분야를 포함한 다양한 접근이 요구됩니다 이러한 구조에서 과학기술투자는 미래에 대한 체계의 효율성을 증대하고, 보다 높은 이익을 가져다 줄 것입니다

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05b
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• pp.787-791
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• 1995

중수형 원자력발전소의 중수는 중성자 흡수반응에 따라 그 일부가 삼중수소화 된다. 삼중수소의 제거반응에 효율적인 고분자 백금촉매를 제조하여 회분식 반응기에서 탈삼중수소 반응실험을 수행하였다. 기액접촉반응탑내에서 고분자 촉매는 탈삼중수소 반응에 유효한 활성이 있음을 확인하였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.2
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• pp.213-220
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• 2016

The needs for the utilization of space in the urban ara due to the increasing population and traffic volume. A Double-deck tunnel can be an appropriate solution. Geosynthetics are inevitably installed between ground and tunnel lining, therefore, geosynthetic-soil interface is also comprises. Dynamic shear behavior of geosynthetic-soil interface affects the dynamic behavior of tunnel, and experimental study is required since the behavior is very complicated. In this study, chemical factors such as acid and basic element in the groundwater and temperature are considered in the laboratory test. Multi-purpose Interface Apparatus(M-PIA) is utilized and submerging periods are 60 and 960 days. Consequently, dynamic shear degradation of geosynthetic-soil interface considering chemical and thermal factors are verified.

• Journal of Korea Water Resources Association
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• v.35 no.2
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• pp.221-229
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• 2002

For the efficient design of baffled Powdered activated carbon(PAC) contractor, which has been widely used in water treatment plant(WTP) against the algae-related odor problems, a CFD(computational fluid dynamics) program was applied. In order to verify the performance of FLOW-3D program, the previously reported results of tracer tests from a pilot-scale PAC contractor(working volume of 288 liters) were compared to those from FLOW 3D. The results of FLOW-3D simulation were very similar to those from tracer tests conducted with the Pilot-scale PAC contactor. On the other hand, the hydrodynamic characteristics of baffled contractor in the P-WTP were simulated by using FLOW-3D. Simulation results on the distribution of PAC particles showed that there are some stagnant parts in the back side of baffles in which PAC Particles are not present. These stagnant parts might decrease the adsorption capacity of PAC particles. When the baffles were changed to maze-type intra-basin baffling, PAC particles were evenly distributed and the amount of stagnant parts reduced. In conclusion, it is anticipated that FLOW-3D simulation could be a viab1e tool for analyzing the hydrodynamic characteristics of structures used in drinking water treatment plant.