• Journal of Advanced Marine Engineering and Technology
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• v.35 no.7
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• pp.881-890
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• 2011

Analyses of performance and behavior of the individual PEM fuel cells (PEMFC) under different operating conditions are of importance optimally to design and efficiently to operate the stack. The paper focuses on experimental analyses of a two-cell stack under different operating conditions, which performance and behavior are measured by the voltage of a cell as well as the stack. Experimental parameters include stoichiometric ratio, temperature of the air supplied under different working stack temperatures and loads. Results showed that the cell voltages are dominantly influenced by the temperature of the air supplied among others. In addition, an inherent difference between the first and the second cell voltage exists because of the tolerances of the cell components and the resulting different over-potentials at different equilibrium states. Furthermore, it is shown that the proton conductivity in the membranes conditioned by the humidity in the cathode channel highly affects the voltage differences of the two cells.

• Journal of the Korean Society of Safety
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• v.23 no.3
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• pp.1-7
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• 2008

As a clean fuel, LNG or LPG is widely used in large restaurants or plants instead of coal. These fuels are easy to use and cheap. However, they are inflammable very much and easily exploded at the worst. So there are many laws and regulations legislated for the handling and usage of the gas facilities. Nevertheless, very harsh explosions occurred in several domestic or foreign places. In this paper a gas detection and alarm system was developed for large facilities. A new concept for connecting many gas detectors was proposed and based upon that a system including hardware and software have been developed and tested. Although up to 16 gas detectors apart 1 km from main controller can be connected currently, this system can be easily expanded for more detectors because each gas detector receiver communicates with main controller using industrial standard RS-485 multi drop technique. Furthermore several additive functions was included for the installation and maintenance convenience.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.73-76
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• 2008

Bipolar Plates for PEMFC have been a key component of fuel cells with MEA, thus in this research they have been fabricated by a compression molding technique after mixing graphite powder with phenol resin. The results have shown the prominent properties compared with those by foreign advanced company with respect to the electrical conductivity and flexural strength. In addition, it has been carried out that the Voltage-Current characteristics comparison according to the unit cell experiments of bipolar plates. As a result, we have obtained good performances and we are going to research the molding feasibility of bipolar plate's flow channel.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.537-538
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• 2004

The performance of the ECWS was predicted for the anticipated operational occurrences. The inadvertent close of loop isolation valve is the most severe case for the five anticipated operational occurrences considered in this design and meets the design criteria of the ECWS. The correlation of critical heat flux for the geometry of three pins sub-channel analysis will be studied in the feature.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.481-484
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• 2006

본 연구에서는 소형 카트용 스택제작에 사용하기 위한 분리판에 관한 연구를 진행하였다. 분리판의 두께가 감소해야 스택의 부피를 줄이고 출력밀도를 높일 수 있기 때문에 분리판 두께 감소를 위한 채널의 깊이 최적화 실험을 진행하였다. 이를 위해 캐소드 채널 깊이에 따른 DMFC 성능의 변화를 관찰하기 위해 캐소드 채널의 깊이를 0.3mm에서부터 1.0mm로 변화시켰다. 채널깊이가 0.5mm일 때 가장 좋은 성능을 보였는데, 원인으로는 단면적 감소에 의한 선속도의 증가와 내부 압력증가를 들 수 있다. 채널깊이 변화에 따른 영향을 분석하기 위해 마노미터를 이용하여 차압을 측정하였고, 임피던스 분석법을 통해 전극의 저항을 측정하였다.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.86-91
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• 2007

A study was performed to understand self-excited pressure fluctuations in the lean premixed flames and to evaluate the effect of Helmholtz resonator on the pressure fluctuations. As low-frequency pressure fluctuations have been reported to cause fatal damage to the combustor and the entire system, Helmholtz-type resonators, which reduce the damage by low-frequency pressure fluctuation in the combustor, are attached to the channel of unburned mixture flow. It is found that the range of low-frequency pressure fluctuations of flame mode 2 is narrowed by the attachment of Helmholtz resonators. From this result, if Helmholtz-type resonators are applied to actual gas turbine combustor, it is confirmed that Helmholtz resonators attached on the fuel discharge hole are also effective for narrowing the range of flame mode 2

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.690-692
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• 2001

A FEM model of the remote-field eddy current effect is presented for zirconium-2.5percent niobium(Zr-2.5%Nb) nuclear reactor pressure tubes to demonstrate the important electromagnetic field. Phenomena that describe this effect. This model is applied to evaluate the optimal operating frequency and detector position. There are many ambiguous experimental results connected with this technique. Finite element calculations can be used in the interpretation of these experimental results even though the electromagnetic fields measured in the remote-field technique are very small.

• Macromolecular Research
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• v.15 no.6
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• pp.581-586
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• 2007

Cast DNA/polyethyleneimine (PEI) blend membranes containing different amounts of DNA were prepared using acid-base interaction and characterized with the aim of understanding the polymer electrolyte membrane properties. Two different molecular weights of PEI were used to provide the mechanical strength, while DNA, a polyelectrolyte, was used for the proton transport channel. Proton conductivity was observed for the DNA/PEI membrane and reached approximately $3.0{\times}10^{-3}S/cm$ for a DNA loading of 16 wt% at $80^{\circ}C$. The proton transport phenomena of the DNA/PEI complexes were investigated in terms of the complexation energy using the density functional theory method. In the case of DNA/PEI, a cisoid-type complex was more favorable for both the formation of the complex and the dissociation of hydrogen from the phosphate. Since the main requirement for proton transport in the polymer matrix is to dissociate the hydrogen from its ionic sites, this suggests the significant role played by the basicity of the matrix.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.4
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• pp.339-345
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• 2007

In the present study, a 10-cell PEMFC stack with straight type cathode flow channels is employed to investigate the effect of inlet air flow header configuration on the overall fuel cell performance. Four different types of inlet flow headers are considered and the flow patterns according to the air inlet flow header configuration are numerically obtained. The computed result for a modified header predicts about 8.5% improvement in the air flow distribution at 10-cell cathode channel inlets. Experiments are also carried out to confirm the numerical findings by measuring actual air flow distributions and the polarization curves of the PEMFC stack.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.2
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• pp.279-284
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• 2013

In this paper, to evaluate the performance of solenoidal typed injector, research and development had been performed on injector controller in order to respond to various performance tests, which is not only economical but easy extensible on its channels. The developed controller based on embedded system is able to precisely control the injection timing and quantity by high-pressured from the injector. Also, it is able to performance evaluation by measuring the electrical characteristics of solenoid. Additionally, it is enable precision timing control of light source and high speed camera as it is able to precisely photograph the timely spray pattern of injector.