• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.1
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• pp.16-22
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• 2003

While passing through the AC/DC section insulators installed at electric railroad catenary, some electric trains undergo mis-operation of main circuit breaker after AC/DC change-over operation. This paper provides insulation resistance measurements of AC/DC section insulators, which confirm the insulation levels of section insulators are below the standard of insulators. The insulation deterioration and pantograph arrangement on the electric train can produce voltage impression on section insulator which induces mis-operation of main circuit breaker To mitigate the insulation deterioration of the section insulator installed at underground railroads, the section insulators have been cleaned periodically, but section insulator structure should be modified to make the section insulator performance perfect. Based on the above analysis, effective modification method of AC/DC section insulator is provided.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.216-221
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• 2007

An experiment was carried out to investigate the effect of a coolant circuit arrangement on the heat transfer and air pressure drop of a fin-tube sensible heat exchanger with the corrugated fin surface. The air inlet temperature was set to $23^{\circ}C$,the relative humidity to 50% and the air inlet flow rate to 20, 22, $25m^3/min$, respectively. while the coolant temperature was set to $7^{\circ}C$, and the coolant mass flow rate to 10, 16, 22kg/min, respectively. Experiment showed that the exchanger having a diameter of 12.7mm with parallel circuit does better performance in sensible heat transfer and air pressure drop than those three of diameter of 12.7mm with a series circuit and that with diameter of 15.88mm with a parallel circuit.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.597-602
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• 2008

The experiment of performance about closed-wet cooling tower(CWCT) was conducted in this study. The test section has the cooling water that flows from top part of a heat exchanger that has an entrance of cooling water with one and multi path. The heat exchanger consists of 15.88mm tubes with ten rows and ten columns and staggered arrangement. In this experiment, heat and mass transfer coefficients and range are calculated with variations of cooling water and path. The results indicated that operating CWCT using two path have the high values of heat and mass transfer coefficients and range than one path.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.154-160
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• 2020

This study analyzed the fire intensity according to the zones classification between traditional market stores using FDS software. Modeling was conducted for the Seomoon traditional market district 4 at Daegu, which places combustibles, such as textiles and clothing near the passageway. The first ignition point assumed a short circuit fire situation at the fourth store combustible. The analysis was conducted under similar conditions as the fire situation in 2016. When there was no section wall, the fire spread rapidly through radiation in all directions from the fire-origin point. After 600 seconds, the mall was burnt to the ground. When section walls were present, however, the fire could be restricted inside the compartment. The first intensity of the two analysis conditions was predicted from the total heat energy from 200 seconds (X₁) to 600 seconds (X₂), where the heat generation rate began to increase rapidly. As a result of installing section walls near the fire point, heat energy generation of approximately 11.12 MW (55.68 %) was delayed. Further analysis of smoke control, according to the section wall arrangement and re-installation facilities, will be needed to study the characteristics of fire in traditional markets comprehensively.