• 사물인터넷융복합논문지
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• 제8권2호
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• pp.7-12
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• 2022

케이블 사고의 주요 원인은 케이블 자체 또는 내·외적으로 전기적, 기계적, 화학적, 열적, 수분침입 등으로 인한 열화의 가속화로 절연성능 감소되고 절연파괴가 발생하여 케이블 사고를 유발하게 된다. 케이블 사고는 과전압, 과전류의 영향으로 절연이 불량한 부분에서 발생할 수 있으므로, 변압기, 차단기의 이상여부, 상간불평형에 의한 지락사고 등을 종합적으로 분석할 필요성이 있다. 케이블의 절연파괴에 의한 지락사고는 케이블 자체의 결함, 케이블 시공불량 뿐만 아니라 운영상의 영향, 전기설비(개폐기, 차단기 등)의 운전 시 아크 등에 의해 발생할 수 있어 사고시점을 전후로 운전 데이터 및 사고 이력에 대한 분석이 필요하다. 이 연구에서는 국내의 한 공장에서 발생한 케이블 사고의 분석을 통하여 케이블 사고의 원인을 고찰하고자 한다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.225-229
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• 2011

The aluminum composite panel are widely used for the external materials of high rise building because of well insulation of heat and sound and improved Constructability. However, the polyethylene in main material of the aluminum composite panel shows weakness in thermal and fire resistances. For this reason, flame is spread more quickly when the fire break out. Therefore, the potentiality of fire spread to the exterior wall is high due to difficulty of early extinguishment and effect of external air. In this study, numerical investigation was performed by using FDS program for flame spread characteristics with various external air velocity and direction in ten-story building with the aluminum composite external materials. As a result, the flame spread velocity is 0.134m/s and it takes 224 seconds for flames to spread to the 10th floor without external air velocity. however, the flame spread velocity decreases 40% and it takes 348 seconds for flames to spread to the 10th floor when external air velocity is 2.5 m/s. and air direction is little effect compared to air velocity.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.27-27
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• 2010

The exact partial discharge pulse should be measured in order to estimate the discharge source in the solid insulation and diagnose the degree of deterioration. Partial discharges generated in the insulation occur in the internal voids or at the edge of the insulation, have unique characteristics following the type and location. When external voltage is applied, Partial discharges occurred in the restrictively presented voids increase the quantity of electrical charge at the discharge onset voltage. The discharge characteristics have remained constant as space is filled by the impurity such as a compound of gases accompanied with discharge. In this study, How to design the insulation about the problems of the built-in diagnostics in the transformer is discussed by the interpretation of electric field.

• 한국수소및신에너지학회논문집
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• 제28권6호
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• pp.618-626
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• 2017

Conventional high temperature reformers are not suitable for hybrid fuel cell systems that use waste heat as a heat source. So, development of a low temperature type reformer is needed. However, the analysis was conducted in two ways to increase the thermal efficiency, because of low reforming rate due to the low heat source. First, it is a way to ger thermal gain from the outside through partial insulation. In the case of one heat source tube and several heat source tubes, we analyzed the effect of partial heat insulation in some cases. Second, we found the most efficient arrangement of the heat source tubes by changing the location of the heat source tubes. The interpretation was carred out using the COMSOL Mutiphysics program.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1015-1017
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• 2003

In a research and development team of high temperature superconducting (HTS) transformer for power distribution, prior to manufacture a single phase 1MVA 22.9 kV/6.6 kV HTS transformer, a 1MVA transformer for insulation test with windings made of copper tapes with the same size as BSCCO-2223 HTS tape was manufactured. The test transformer was composed of both the copper windings of double pancake type and the shell type core of laminated silicon steel plates. The characteristics tests of the test transformer were performed, such as no load test, load test and short test at 77k using liquid nitrogen. Insulation tests, lightning impulse test, power-frequency voltage test and external insulation test, were accomplished also.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.454-456
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• 2003

This paper describes a type test results of 154 kV transmission line arrester with external gap. The test was carried on surge arrester unit and line arrester with external gap, respectively. Withstand voltage test demonstrate the voltage withstand capability of the line arrester with external series gap under the dry and wet conditions. In insulation coordination test external series gap shall be discharged every time when lightning impulse voltage with the steepness of more than 1500 $kV/{\mu}s$ are applied under the wet condition.

• 한국대기환경학회지
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• 제28권6호
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• pp.675-687
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• 2012

Applying an external electric field across air filter media is one of methods to improve the filtration performance. Metal wire meshes have been commonly used as electrodes situated on both sides of a thick filter pad. For a thin filter medium a short circuit, known as the biggest drawback for applying an external electric field to air filter, can occur at the closest point between electrodes. In this study several types of insulated meshes were prepared by coating #50 meshes with a dielectric material, Nylon 66, and the filtration property of air filter was evaluated at the presence of external electric field using those insulated meshes as electrodes and compared with that of filters using bared meshes. The collection efficiency of tested filter was increased from 78% to 95% for singly charged 100 nm particles by application of external electric field. As a result, there was no significant difference in collection efficiency between filters with insulated and bared electrodes. Similar results could be also seen from the tests using polydisperse particles. Finally, through this study, we found that the insulation of mesh electrodes doesn't affect the filtration performance of fibrous air filter under external electric field.

• 한국정밀공학회지
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• 제34권4호
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• pp.287-292
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• 2017

A gas turbine is the main equipment used in a combined heat and power plant. It generates a high sound pressure noise level. To reduce the noise level, an enclosure is installed around the turbine. The sound insulation performance of the enclosure affects the amount of external noise reduction. In this study, a sound transmission loss analysis is performed using the boundary element method to predict sound insulation performance according to the numbers and shapes of the supporter. Radiated noise analysis is also performed for the main external points of the enclosure using ray-acoustics. The results of these analyses are presented and a design plan is proposed that reduces the sound pressure noise level of the enclosure.

• 한국추진공학회지
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• 제10권3호
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• pp.53-59
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• 2006

본 연구에서는 미사일의 외면에 단열재의 재료로 사용되는 재료들의 종류 및 배합비 별로 적외선 램프 시험 장비를 이용하여 단열 성능 평가와 기계적/열적 특성치를 측정하였다. 실험 결과 다공성 충전제 함유량이 증가할수록 단열성능은 증진되나 기계적 특성은 저하하였다. 다공성 충전제 종류 중에서 Epoxy/Phenolic Microballoon이 가장 우수한 기계적 특성과 낮은 열전도도 값을 보여 주었다. Epoxy/cork 단열재는 낮은 기계적 특성치와 높은 열전도도 간을 보여주었으나, 적외선 램프 실험에서는 가장 우수한 단열 성능을 가졌다.

• 한국항공운항학회지
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• 제20권3호
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• pp.44-50
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• 2012

The noise reduction is important one of considerations in the process of a civil aircraft development program. External noise sources are classified into an air-born source and a structure-born source. Among these noise sources, the most affected noise source into a cabin is the air-born noise source from an engine or propeller. The external noise is transmitted into the cabin through the fuselage structure of airplane which are composed of an fuselage structure, an interior trim panel and an acoustic insulation layer between an fuselage structure and an interior trim panel. Therefore, appropriate fuselage structure and acoustic insulation layer is very important to reduce the internal noise level. In this paper, the vibro-acoustic coupled analysis of the cabin noise of the 80~90 seats regional turboprop aircraft is carried out to validate the acoustic analysis method using Direct BEM and FEM. The sound pressure level onto the fuselage skin is acquired by fan-source noise analysis using BEM, and which sound pressure is used as acoustic noise source in vibro-acoustic noise analysis for cabin noise analysis using FEM.