• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.450-451
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• 2008

Most of the transmission lines in Korea pass through a mountains. The forest fire occurred in around the transmission lines make an accident such as flashover and faults in the power transmission lines. In spite of that risk, there are no research on the flashover characteristics by fires in electric discharge engineering in our country. Therefore, by studying flame's electrical conductivity, the paper recommended measures that can minimize transmission line's flashover accidents in the future, which can be caused by forest fire in a region where transmission lines pass through.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1207-1208
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• 2008

Forest Fire can cause a serious damage to overhead conductors. Therefore, the detailed investigation for the changes of mechanical and electrical properties of damaged conductors should be carried out to understand the effect of forest fires on conductors. This is very much important to maintain transmission line safely. Especially, this paper describes the changes of mechanical and electrical properties of conductor due to forest fire and agents. The detailed will be given in the text.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.768-769
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• 2015

본 논문에서는 3상, 1250MVA, 345kV급 전력용 변압기의 하우징 영역에 대한 온도상승 연구를 유한요소법과 시험을 통하여 수행하였다. 하우징 영역에 대한 전자계 요한요소 해석을 통해 와전류 손실을 수행하였고, 이를 열원으로 하여 변압기 내 외부 냉각조건을 고려하여 온도상승 분포와 최고온도 상승 값을 해석하였다. 이를 제작된 변압기를 대상으로 온도센서 및 열화상 카메라를 이용한 측정 데이터와 비교하여 검증하였다.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.2
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• pp.91-96
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• 1994

Intake gases other than air, which is composed of oxygen, nitrogen, carbon dioxide, and argon, are used to study their effects on the performance of the diesel engine experimentally. The engine is operated at constant speed and fixed fuel injection timing, and cylinder pressure and heat release rate are measured at various intake gas compositions. The results show that increase of oxygen concentration improves the performance of the engine generally. The adverse effect is observed when the oxygen concentration is increased over the critical oxygen concentration of this test, mainly because of the over-shortened ignition delay. Increase of carbon dioxide concentration degardes the performance of the engine, mainly due to the lower specific heat ratio of carbon dioxide. Adding argon gas to the intake gas improves the overall performance. Finally, it is found that two most influencing factors affecting the performance of the diesel engine in this study are ignition delay and speific heat ratio of the intake gas.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.3
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• pp.52-57
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• 2004

Many kinds of gases, such as erosion gas, dilution gas, and toxic gas have been used in manufacturing process of LCD at semiconductor. In order to increase accumulation rate of manufacturing process, high degree of purity in these gases and minimized metalllic dust are required. All wetted stainless steel surface must be 316L electro-polished with $0254{\mu}m$ in average. Based on the AES analysis, Cr/Fe 11 and $Cr_2O_3$ thickness $25{\AA}$ are measured Molybdenum and silicon contaminants which is characteristic of stainless steel and oxygen were found on the surface.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.8
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• pp.839-846
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• 2007

Nd:YAG pulse laser fillet welding of stainless steel plate was simulated to find welding condition by using commercial finite element code MARC. Full model of AISI 304 stainless steel plate was considered and user subroutines were applied to boundary condition for the heat transfer. Material properties such as conductivity, specific heat, mass density and latent heat were given as a function of temperature. As results, Three dimensional heat source model for pulse laser beam conditions of fillet welding has been designed by the comparison between the finite element analysis results and experimental data on AISI 304 stainless steel plate. Nd:YAG laser welding for AISI 304 stainless steel was successfully simulated and it should be useful to determine optimal welding condition.

• Korean Management Science Review
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• v.25 no.3
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• pp.123-133
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• 2008

We investigate the relationship between ownership structure and firm performance. For this paper, we use the 'donation' figure from the income statement of each firm as a measure of firm Performance lather than short-term financial measure that has been wifely used by previous studies. Our results are consistent with the idea that family ownership is both prevalent and substantial in Korea. More importantly, however, non-family firms are found to give more donations than family firms. This suggests that non-family firms more readily recognize the significance of corporate social responsibility and play an active role in philanthropy.

• 월간 기계설비
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• s.30
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• pp.91-97
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• 1993

원적외선은 인류가 최초로 이용한 난방열원이다. 불을 사용하기 이전의 유일한 난방은 태양열을 받는 것이었으며, 그 태양열 중 인체를 따뜻하게 해주는 빛이 바로 원적외선이기 때문이다. 현대 과학에서는 이미 1920년대에 원적외선 난방이론이 정립되었으며, 1940년대에 들어서는 미국에서 원적외선 튜브히터가 개발되어 충고가 높고 면적이 넓어 다른 난방시스템으로는 불가능했던 산업 및 상업용건물의 난방이 가능해졌을 뿐만 아니라 복사난방의 대표적인 시스템으로 인정되고 있다. 우리나라의 경우는 `80년대 초반부터 원적외선 히터가 선보이기 시작했고, 극히 일부 공장건물에 사용된 실적이 있으나 아직까지 원적외선 난방시스템 자체에 대한 인식이 부족하고 이 분야에 대한 자료 또한 전무한 실정이다. 이에 필자는 수년간 외국(특히 미국)의 자료를 분석하고 현지를 답사하므로써 확인될 수 있었던 원적외선 난방시스템의 유용성을 토대로 하여 이론과 실제적인 내용을 다루어 보고자 하는 것이다.

• Journal of Advanced Marine Engineering and Technology
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• v.6 no.2
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• pp.51-68
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• 1982

A method of calculation of temperature distribution during welding was studied and compared with the existing formulas and experimental results. In contrast to the existing formulas which are founded on the suppositions that the heat source is a point and that the dimensions of welded pieces are infinite, we tried to make the distribution of calorific density of heat source approach reality more closely, so we considered it as a normal distribution of Gauss, and we presented the formulas for calculation of temperature during welding. We also used the principle of superposition for the temperature calculations of finite welded pieces. We compared the formulas presented in this paper with the existing formulas by calculations for the welding of various materials, and considerable differences around the heat source were convinced. The thermal cycles of various points were traced through the welding experiments for the mild steel, and they were compared with the results of calculations.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.434-440
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• 2000

The atomization characteristics of air-assist atomizer which is surrounded by a coflowing airstream is investigated. The air-assist, coflow air stream had swirl imparted to them in the same direction with 45 degree's angle swillers. The fuel and air entered the combustor at ambient temperature and the combustor was operated in an unconfined environment. Diesel fuel was used for all the experiments. Drop size and mean velocity are reported for certain distances downstream from the nozzle. The droplet size and velocity measurements were performed using a two-component phase/Doppler particle analyzer and velocity profiles across the entire flowfield are presented.