• 한국수소및신에너지학회논문집
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• 제21권4호
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• pp.258-263
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• 2010

A numerical stack model has been developed to predict the temperature at a constant-load operation of molten carbonate fuel cell stacks. For the validity of the model, the simulated results with several boundary conditions were compared in the cell temperature data obtained from 75 kW class MCFC stack operation. It was shown that the simulated results with the existing boundary condition, which the stack outlet temperature was fixed at $650^{\circ}C$, didn't match well with the measured data. On the other hand, the stack model with the outlet temperature modified by the outlet manifold temperature measured from the stack under several electric loads was found to explain the measured cell temperature distribution well. The results show that the model can be used to predict the cell temperature distribution in the stacks by the measurement of the manifold outlet temperature.

• 한국수소및신에너지학회논문집
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• 제21권5호
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• pp.419-424
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• 2010

The 125kW external reforming (ER) type molten carbonate fuel cell (MCFC) system for developing a commercial prototype has been operated at Boryeong thermal power plant site since the end of 2009. The system consists of 125kW stack with $10,000 cm^2$ effective area, mechanical balance of plant (MBOP) with anode recycle system, and electrical balance of plant (EBOP). The 125kW MCFC stack installed in December, 2009 has been operated from January, 2010 after 20 days pre-treatment. The stack open circuit voltage (OCV) was 214V at initial load operation, which approaches the thermodynamically theoretical voltage. The stack voltage remained stable range from 160V to 180V at the maximum generating power of 120 kW DC. The stack has been operated for 3,270 hours and operated at rated power for 1,200 hours.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 제17회 워크샵 및 추계학술대회
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• pp.552-552
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• 2005

• 한국수소및신에너지학회논문집
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• 제22권6호
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• pp.852-858
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• 2011

This paper is aiming to estimate the mutual influence of the stack cooling performances with the operation modes of the thermal management system for the hydrogen fuel cell vehicles. The heat capacity of the thermal management system was measured by varying the operating modes such as stack cooling heat exchanger only (Mode 1), stack cooling and electric devices cooling heat exchangers (Mode 2), and stack cooling and electric devices cooling heat exchangers with an operation of the condenser (Mode 3).As the results, Performance of the thermal management system (TMS) at Mode 3 decreased up to 34.0%, compared with the result of the Mode 1. In addition, in order to optimize the performance of TMS, the entropy change of stack cooling heat exchanger using irreversibility analysis technique was analyzed with the relationship between entropy generation and entering air velocity of the thermal management system.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.927-930
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• 2003

In this paper, a design of processor IP for TCP/IP protocol stack is described. The processor consists of input and output buffer memory with dual bank structure, 32-bit RISC microprocessor core, DMA unit with on-the-fly checksum capability. To handle the various modes of TCP/IP protocol, hardware and software co-design approach is used rather than the conventional state machine based design. To eliminate delay time due to the data transfer and checksum operation, DAM module which can execute the checksum operation on-the-fly along with data transfer operation is adopted. By programming the on-chip code ROM of RISC processor differently. the designed stack processor can support the packet format conversion operations required in the various TCP/IP protocols.

• 설비공학논문집
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• 제20권3호
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• pp.197-204
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• 2008

DMFC(Direct Methanol Fuel Cell) is one of promising candidates for power sources of small mobile IT devices like notebook, cell phone, and so on. Efficient operation of fuel cell system is very important for long-sustained power supply because of limited fuel tank size. It is necessary to investigate operation characteristics of fuel cell stack for optimal control of DMFC system. The generated voltage was modeled according to various operating condition; methanol concentration, stack temperature, and load current. It is inevitable for methanol solution at anode to cross over to cathode through MEA(membrane electrode assembly), which reduces the system efficiency and increases fuel consumption. In this study, optimal operation conditions are proposed by analyzing stack performance model, cross-over phenomenon, and system efficiency.

• 멤브레인
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• 제33권3호
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• pp.127-136
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• 2023

본 연구에서는 실리카 복합막 기반 고분자 전해질막을 5단 연료전지 스택에 적용하여 성능 평가를 수행하였다. 이를 통하여, 개별 구성 요소의 성능도 중요하지만, 전체적인 관점에서 공급되는 연료의 유량이 스택 성능에 중요한 역할을 하며, 특히 수소의 유량에 크게 의존한다는 사실이 확인하였다. 산소의 유량을 증가시켜도 성능의 변화는 미미한 반면, 수소의 유량을 증가시키면 성능이 향상되는 것을 확인하였다. 그러나 수소의 유량 증가는 수소와 산소 유량 비율의 불균형을 초래하여 장기적으로는 스택 성능과 내구성을 저하시키는 문제가 관찰되었다. 이러한 현상을 스택 구성 요소 및 개별 단위 셀에서도 관찰할 수 있었으며, 따라서 스택 운전 시 각 구성 요소의 성능을 최적화하는 것 외에도 균일한 유량 제어를 위해 유로 설계 및 운전 조건을 최적화하는 것이 중요하다는 것을 알 수 있었다. 마지막으로 실리카 복합막은 최대 출력 기준 25 W 이상의 성능을 나타내어 실제 연료전지 시스템에 적용하기에 충분한 성능을 갖춘 것으로 판단된다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.125.1-125.1
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• 2010

A high efficiency polymer electrolyte membrane (PEM) fuel cell stack was developed for pressurized pure hydrogen and oxygen supplying conditions. The design objective for the cell stack was to maximize the electric efficiency and to minimize exhaust-gas emissions from it simultaneously. To achieve this objective, the cell stack was designed to use pure hydrogen and oxygen as fuel and oxidant, respectively, and to be operated under high gas inlet pressures and in a stage-wise dead-end operation mode. Major components constituting the cell stack, such as membrane electrode assembly, bipolar-plate, and gasket, have been developed to meet a target durability even in severe operating conditions: high gas inlet pressures and usage of pure oxygen. A high-power fuel cell stack was assembled using these components to verify the performance. The cell stack showed a good performance in terms of the efficiency and maximum power output.

• 한국자동차공학회논문집
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• 제22권7호
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• pp.76-83
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• 2014

During PEMFC(Proton Exchange Membrane Fuel Cell) operation monitoring and diagnosis are important issues for reliability and durability. Stack defect can be followed by a critical cell voltage drop in the stack. One method for monitoring the cell voltage is CVM(Cell Voltage Monitoring), where all cells in the stack are electrically connected to a voltage measuring system and monitored these voltages. The other methods are based on the EIS(Electrochemical Impedance Spectroscopy) and on nonlinear frequency response. In this paper, intermodulation(IM) method for diagnosis PEMFC stack is introduced. To detect one or more critical PEMFC cell voltage PEMFC stack is excited by two or more test sinusoid current, and the frequency response of the stack voltage is analyzed. If one or more critical cell voltage exists, higher harmonics on the voltage frequency spectrum will appear. For the proposed IM method, stack simulation and experiments are conducted.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2144-2148
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• 2008

Kerosene-driven solid oxide fuel cell (SOFC) system with reformer, desulfurizer and after-burner was mainly developed for this study. Originally the system was developed for 1kW class SOFC system for residential power generation (RPG) application. As a preliminary study of 1kW class SOFC system operation, a short stack was applied to the system. The short stack consists of 7 cells of $10cm{\times}10cm$ area and was operated at $720^{\circ}C$. The effect of anode inlet gas composition to stack performance was investigated. Firstly, I-V characteristics of SOFC with different fuel of kerosene and hydrogen were studied. Secondly $CH_4$ internal reforming was performed at various anode inlet gas compositions of $H_2$, $CH_4$ and $H_2O$. Through these experiments the effects of each anode inlet gas component to stack performance were analyzed and the significant operating parameters were iscussed.