• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.90.1-90.1
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• 2011

연료전지 분리판은 연료, 공기, 수분이 흐를 수 있는 채널들이 포함되어 있으며, 전지들에 의해서 생산되는 전류를 흐르게 할 수 있는 전기전도성을 가져야 할 필요가 있다. 일반적인 금속판들은 연료전지 스택 내의 산성 분위기에 존재해야 하기 때문에 표면 부식이 쉽게 발생한다. 그라핀(graphene)은 우수한 전기전도성을 가지고 있을뿐만 아니라 물리화학적 내식성 및 내구성을 가지고 있어 연료전지 분리판으로서 응용이 가능할 것으로 판단된다. 본 연구에서는 일반적으로 널리 사용하고 있는 스테인리스강(stainless steel)을 모재로 사용하였으며, 그라핀을 전기분무법(electro spray coating)으로 코팅하여 스테인리스강의 내식성 및 전기전도성을 동시에 향상시키고자 하였다. 그라핀은 에탄올을 용매로 사용하여 분산하였으며, 분산제로 소량의 다이페닐다이에톡시실란(diphenyldiethoxysilane)을 첨가하여 코팅용액을 제작하였다. 코팅공정은 15kV 전압을 가하여 1시간동안 코팅을 진해하였으며, 그라핀-스테인리스강 모재의 미세구조를 전자현미경과 광학현미경을 통하여 관찰하였다. 또한 X-선 회절분석법을 이용하여 그라핀의 결정구조를 분석하였다. 한편 스택의 내부와 유사한 산화성 분위를 모사하기 위해 $80^{\circ}C$의 0.1N $H_2SO_4+2ppm\;F^-$ 용액에서 내식성 실험을 수행하였고, 면간접촉저항도 측정하였다. 그라핀이 코팅된 스테인리스강 시편은 고분자전해질 연료전지 분리판의 요구조건을 만족하였으며, 연료전지 분리판으로서의 적용가능성을 확인하였다.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.3
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• pp.65-71
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• 2007

For chip-stack package applications, Cu filling characteristics into trench vias of $75{\sim}10\;{\mu}m$ width and 3 mm length were investigated with variations of the electroplating current density and the speed of a rotating disc electrode (RDE). Cu filling characteristics into trench vias were improved with increasing the RDE speed. There was a Nernst relationship between half width of trench vias of Cu filling ratio higher than 95% and the minimum RDE speed, and the half width of trenches with 95% Cu filling ratio was linearly proportional to the reciprocal of root of the minimum RED speed.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.160-165
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• 2009

연료전지 분리판은 연료전지 스택을 구성하는 부품 중에서 가장 많은 수량이 사용되는 부품의 하나로서 연료전지의 출력밀도(Power Density, W/L), 비출력(Specific Power, W/kg) 및 가격($/kWe) 관점에서 가능한 저가의 소재 및 제조공정으로 경량, 박형화가 이루어져야 하는 핵심 부품이다. 이러한 저가의 경량, 박형화 분리판 개발의 전제조건은 연료전지 스택에서 요구하는 다양한 물성, 장기수명 및 신뢰성은 나타내는 내구성을 만족해야 하는 것이다. 이렇듯 연료전지 분리판은 다음과 같은 요구 조건을 만족해야 한다. 높은 전기전도도, 전기화학적 부식 저항성, 화학적 안전성, 가스 기밀성, 기계적 강도 및 가공성 등이라 하겠다. 본 연구에서는 분리판의 요구 조건을 만족할 수 있는 분리판을 제작하기 위하여 고분자 복합소재(PCB; Printed Circuit Board)를 이용하여 전기도금을 통해 Cu/Au(1st PCB 분리판)과 Cu/Ni/Au(2st PCB 분리판)을 코팅하여 분리판을 제작하였다. 제조된 분리판을 이용하여, 접촉저항, 부식특성, 가스 기밀성, 기계적 강도를 분석하였으며, 단위전지를 제작 하여 상용 Graphite 분리판과 성능을 비교분석하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.90.1-90.1
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• 2011

This technology is applicable to Electrical vehicle that using Energy from Hydrogen Fueled Cell. Electricity & water is got from chemical reaction between H2 & O2 in stack. This technology is used when fault diagnosis of Fuel cell is needed. It is General method that measure each cell's voltage of stack for fault diagnosis. but, this technology is method of measuring entire voltage of stack. For this reason, fault diagnosis system is simplified and cost of system is lower than previous one. In normal stack condition, characteristic graph of voltage-current has linearity. In fault stack condition, it has non-linearity. we use this characteristic to diagnosis of stack fault. In this technology, Specific frequency current is injected into stack & Stack voltage is measured in response. After that, stack voltage difference is analyzed to diagnosis of stack fault. Presently, Development of current injection module & basic program of THDA is finished. in future we will develop the technology of precise measurement technology about entire stack voltage.

• Journal of Hydrogen and New Energy
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• v.11 no.3
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• pp.137-147
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• 2000

Not only study of fuel cell performance but study of fuel cell application is very important, therefore these studies were paralleled together for the commercialization of exciting power generation. The objective of this study is to determine the characteristics of shaft power and efficiency as a function of rpm and to compare natural convection air method to forced air method. From these results, performance of forced air was better than that of natural convection air because it enables to improve mass transportation by increasing air flow rate. With decreasing shaft power, efficiency of fuel cell decreases remarkably because dc motor drives at the low range of efficiency. Fuel cell powered vehicle has to be driven considering efficiency and shaft power. It should be driven at 35-45% of efficiency and 0.55-0.75v/cell.

• Plant Journal
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• v.10 no.3
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• pp.45-51
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• 2014

This study performs several experiments on a newly developed temperature safety system that can be used for residential building heating systems, the heat source of which is derived from a conventional fuel cell. Prior to this, the hot water made from a fuel cell was not used in residential housing but just went to waste. The present safety system is installed in the current underfloor heating system. At first we used the CFD technique to develop a new heat exchanger. The fuel cell must satisfy the thermal conditions of the inlet temperature being $55^{\circ}C$ and the outlet temperature being $60^{\circ}C$. But variations in weather cause fluctuations in the heating water temperature. The experimental results show our new system capable of maintaining the temperature difference within a ${\pm}0.5^{\circ}C$ range. So we believe that our new PFMFC fuel cell stack array is a good candidate for being used in residential heating systems.

• Journal of the Korean Electrochemical Society
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• v.7 no.2
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• pp.69-79
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• 2004

To correctly simulate performance characteristics of fuel cells with a modeling method, various physical and chemical phenomena must be considered in fuel cells. In this study, performance characteristics of planar solid oxide fuel cells were simulated by a commercial CFD code, CFD-ACE+. Through simultaneous considerations for mass transfer, heat transfer and charge movement according to electrochemical reactions in the 3-dimensional planar SOFC unit stack, we could successfully predict performance characteristics of solid oxide fuel cells under operation for structural and progress variables. In other words, we solved mass fraction distribution of reactants and products for diffusion and movement, and investigated qualitative and quantitative analysis for performance characteristics in the SOFC unit stack through internal temperature distribution and polarization curve for electrical characteristics. Through this study, we could effectively predict performance characteristics with variables in the unit stack of planar SOFCs and present systematic approach for SOFCs under operation by computer simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.10B
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• pp.1182-1191
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• 2011

In this paper, we propose a network-based IP mobility management scheme, called Access Independent Mobile Service with IPv4/IPv6 Dual Stack (AIMS-DS), which can provide high-quality multimedia services to IPv4/IPv6 dual-stack mobile nodes (MNs) without any interruption over various wireless/wired access networks. The proposed scheme provides an MN with a fast and reliable mobility service among heterogeneous wireless access networks through the network-based control, the complete separation method of control and data plane, the cross-layer (layer2 and layer3) interworking method for handover control acceleration, etc, In addition, the proposed AIMS-DS can provide seamless mobility service to an MN under the environments of IPv4/IPv6 coexisting networks through the home address mobility support and transport network support. Through performance evaluation with computer simulations, we have shown the superiority of the proposed AIMS-DS in terms of handover latency, packet 1085 and packet delivery latency.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.149-154
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• 2011

In order to explore properties of various rubber compounds after thermal aging under the condition similar to the operating environment of a fuel cell-stack, heat resistance and compression set of those compounds were investigated for a long term operation in $H_2SO_4$, $H_2O$, and LLC (ethylene glycol : $H_2O=50:50$) solution. It was assumed that aging Acrylonitrile butadiene rubber (NBR) and Elthylene Propylene diene rubber (EDPM) compound in the solution resulted in discoloration as time passed. It was also found that hydrolysis was developed on the Silicone rubber (VMQ) compound intentionally aged under acidic condition by means of TGA, SEM, and EDS analysis.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.05b
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• pp.318-321
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• 2003

최근 ITU와 FS-VDSL 등의 국제 표준 기구에서 ATM과 IP 기반에서 VDSL 기술을 이용한 VOD 서비스 실현을 위해 서비스, 망 구조 및 프로토콜 등에 대해 연구가 진행 중에 있다 본 논문에서는 ATM/VDSL 기반의 VOD 서비스 제공을 위해 종단간 ATM 모델의 망 구성과 프로토콜 스택을 제시하고 분석한다. 그리고, 이 모델에 대해 IGMP (Internet Group Management Protocol)HTSP(Real Time Streaming Protocol)와 DSM-CC (Digital Storage Media Command and Control) 을 이용하는 서버와 셋탑박스 간의 VOD 서비스 신호 절차를 제안하고 분석한다.