• Journal of the Korean Society for Precision Engineering
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• v.31 no.10
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• pp.955-965
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• 2014

Transport phenomena of reactant and product are directly linked to intrinsic inhomogeneous random configurations of catalyst layer (CL) that consist of ionomer, carbon-supported catalyst (Pt/C), and pores. Hence, electrochemically active surface area (ECSA) of Pt/C is dominated by geometrical morphology of mass transport path. Undoubtedly these ECSAs are key factor of total fuel cell efficiency. In this study, non-deterministic micro-scale CLs were randomly generated by Monte Carlo method and implemented with the percolation process. To ensure valid inference about Pt/C catalyst utilization, 600 samples were chosen as the number of necessary samples with 95% confidence level. Statistic results of 600 samples generated under particular condition (20vol% Pt/C, 30vol% ionomer, 50vol% pore, and 20nm particle diameter) reveal only 18.2%~81.0% of Pt/C can construct ECSAs with mean value of 53.8%. This study indicates that the catalyst utilization in fuel cell CLs cannot be identical notwithstanding the same design condition.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.7
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• pp.46-53
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• 2007

Micro-grid consists of micro-sources which adopt environmentally friendly and reliable power sources such as Fuel-Cell and Micro-Turbines with independent real and reactive power control capability for providing premium power quality. This paper deals with the basic aspect of dynamic modeling and the stability analysis of the micro-grid system. The fundamental frequency model of the micro-source inverters are considered to form a dynamic model of the micro-grid system Stability analysis is performed based on the linearized dynamic model of the micro-grid system Case study results show the parameters affecting the stability of the micro-grid.

• Proceedings of the KWS Conference
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• 2004.05a
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• pp.302-304
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• 2004

Nuclear fuel elements containing dry recycling nuclear fuel pellets for the irradiation test in a reactor were remotely fabricated from spent PWR fuel materials in a hot cell. End closure welding as well as seal tube welding for thermal sensor of the elements was performed by Nd:YAG laser. The soundness of the end closure welds and seal tube welds for the elements were evaluated by a precise X-ray inspection system composed of a micro-focus X-ray generator with an image intensifier and a real time camera system. Then, helium leak test was performed for the elements. The soundness of the welds of the fuel elements was confirmed by the X-ray inspection and helium leak test. The irradiation test for the fuel elements were successfully completed at the HANARO research reactor.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.474-476
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• 2006

본 연구에서는 다양한 두께, loading 및 기공 구조를 갖는 MPL을 형성하여 DMFC용 확산층을 제조하였다. 본 실험에서 제조한 확산층의 경우, 두께가 증가하면서 기공이 micro-pore에서 meso-pore 영역으로 옮겨감을 확인할 수 있었으며, 또한 기공구조에 따라 공기 투과도 특성이 변화하는 것을 확인할 수 있었다 각각의 확산층은 서로 다른 운전 조건에서 우수한 성능(흑은 안정적인 성능)을 갖는 것으로 확인되었으며, 이는 용도에 따른 확산층의 적합한 구조 설계가 요구됨을 의미한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.611-612
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• 2006

• Korean Membrane Journal
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• v.1 no.1
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• pp.1-7
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• 1999

Pd-ceramic composite membranes and catalytic membrane reactors(CMR) have been studied for hydrogen and its isotopes (deuterium and tritium) purification and recovery in the fusion reactor fuel cycle. Particularly a closed-loop process has been studied for recovering tritium from tritiated water by means of a CMR in which the water gas shift reaction takes place. The development of the techniques for coating micro-porous ceramic tubes with Pd and Pd/Ag thin layers is described : P composite membranes have been produced by electroless deposition (Pd/Ag film of 10-20 $\mu$m) and rolling of thin metal sheets (Pd and Pd/Ag membranes of 50-70 $\mu$m). Experimental results of the electroless membranes have shown a not complete hydrogen selectivity because of the presence of some defects(micro-holes) in the metallic thin layer. Conversely the rolled thin Pd and Pd/ag membranes have separated hydrogen from the other gases with a complete selectivity giving rise to a slightly larger (about a factor 1.7) mass transfer resistance with respect to the electroless membranes. Experimental tests have confirmed the good performances of the rolled membranes in terms of chemical stability over several weeks of operation. Therefore these rolled membranes and CMR are adequate for applications in the fusion reactor fuel cycle as well as in the industrial processes where high pure hydrogen is required (i.e. hydrocarbon reforming for fuel cell)

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.467-470
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• 2006

For a mobile application such as cellular phone, micro fuel cells should be extremely compact and thin. RHFC can be an alternative solution because RHFC gives higher power density than DMFC and does not need ahydrogen storage vessel In this paper, RHFC using methanol fuel is made as a novel planar design without a PROX. Both reformer and cell are made closely in a same plate to share the heater of reformer with the cell. The PBI membrane is used in the cell. The reason is that high temperature of reformer can cause a performance drop when perfluorosulfonic acid membrane such as Nafion is used such a high temperature operation also guarantees the higher CO tolerance to MEA catalyst. The cell is designed as an air-breathing type which the cathode of the cell is opened to the air. The commercial Cu/ZnO/Al2O3 steam reformer catalyst is packed in reformer channel. The active area of MEA is $11.9cm^2$ and the peak power density was $27.5mW/cm^2$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.52-58
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• 2005

The concept of the Micro-Grid comprising Micro-Sources supplying both heat and power ranging from several [KW] to 1[MW] to local customers is proposed by CERTS(Consortium for Electric Reliability Technology Solutions). Micro-Sources adopt environmentally friendly and reliable power sources such as Fuel-Cell and Micro-Turbines. Micro-Sources adopt voltage source inverter with AC grid system in order to provide independent real and reactive power control for premium power quality. Thus Micro-Source needs series inductance for interfacing with AC grid system. With this reason, we propose a technique that can decide the optimal size of the inductor for effective transfer of the power into the grid.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.446_447
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• 2009

This paper describes operational analysis results of the DC micro-grid using detailed model of distributed generation. Detailed model of wind power generation, photo-voltaic generation, fuel-cell generation was implemented with the user-defined model of PSCAD/EMTDC software that is coded with C-language. Various simulation results confirm that the DC micro-grid can operate without any problem in both the interconnected mode and the islanded mode. The operation analysis result confirms that the DC micro-grid make it feasible to provide power to the load stably.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1738-1743
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• 2008

Environmental issue is one of the key factors to industry area using fossil fuels, because it accelerates the global warming. So it is supposed to reduce greenhouse gases around the developed nations of the world at times go. This issue is especially for the power industry. Under this background, MicroGrid system that consists of Distributed Energy Resources (DER) system, such as natural power system (wind, solar) and fuel-cell, co-generation, also known as CHP (Combined heat and power), has been developed greatly during the last 10 years. This paper adopts optimal model using GAMS to develop methods for conducting an integrated assessment of MicroGrid system.