• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 일렉트렛트 및 응용기술
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• pp.36-40
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• 2002

This paper presents the results of a investigation, a development of the measuring system for grounding properties in live-line. The importance of the grounding system and it's property has been increased with the development, enlarge in capacity, of electrical industry. Moreover, with the rapid growth of communication and precision industry, now, we should consider the grounding properties to ensure the stable and/or safe operation. But the conventional measuring system is not proper to measure the grounding properties of the system, voltage applied. So, in this investigation, we proposed a new method for live-line measurement and develope the system. And through the field test we could confirm the superior performance of th developed system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.482-484
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• 2001

Earth resistivity and changing of grounding electrode's shape are very important factor to reduce grounding resistance. Earth resistivity has different values according to property of soil and is effected by temperature, climate, and environment. This Paper describes the effect of the grounding resistance according to the grounding type such as driven rod, counterpoise grounding and mesh grounding. And also grounding resistance values with earth resistivity and shape of grounding electrode were represented in this paper.

• 대한조선학회논문집
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• 제31권1호
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• pp.121-132
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• 1994

본 연구에서는 선저보강판부재의 좌초시 손상거동특성을 규명하기 위하여 시리즈 실험을 수행하였다. 즉, 강체웨지가 선저보강판을 연직방향에서 준정적으로 진입할 때 여러가지 파라메타 즉 1) 판의 종횡비, 2)웨지각도, 3)판두께, 4)웨지형상 및 5)종 횡보강재의 변화에 따른 시리즈 실험을 수행하고, 좌초시 선저보강판의 좌초하중-진입량 관계와 흡수에너지-진입량 관계 등에 관한 파라메타들의 영향을 분석하였다.

• 조명전기설비학회논문지
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• 제26권5호
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• pp.58-64
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• 2012

In electric power supply systems, an earthing system determines the electric potential of the conductors related to that of the Earth's surface. The choice of earthing system has implications for the safety of the power supply systems. There are considerably different regulations for earthing (grounding) systems in each country. A protective earth(PE) conductor ensures that all exposed conductive surfaces are at the same electric potential as the earth surface. This paper deals with that when PEN conductor of TN-C-S system is disconnected, dangerous touch voltage causes personnel body to be harmed and human being's property to be damaged seriously. For this reason, this paper explains how serious problems can occur when the fault current flows. As a consequence, we can understand how we can design earthing system properly to ensure the personnel safety against earth faults. The result shows the way that TN-C-S system can be applied safely in Korea.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2003년도 학술대회논문집
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• pp.369-372
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• 2003

To obtain a low ground resistance in high resistivity soil or in insufficient place such as downtown, long vertical ground rods are often used. However, if the lightning current or fault current with high frequency flows into the grounding system, the ground impedance is remarkedly increased. This paper presents how the impulse and fault current works on the long. vertical ground rods associated with incoming points. When the test current was injected at the bottom of ground rod, the potential waveform of ground rod includes the oscillation with high frequency.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.1807-1813
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• 2018

In this paper, the fault line selection and location problems of single line-to-ground (SLG) fault in distribution network are addressed. Firstly, the adaptive filtering property for empirical mode decomposition is formulated. Then in view of the different characteristics showed by the intrinsic mode functions(IMF) under different fault inception angles obtained by empirical mode decomposition, the sign of peak value about the low-frequency IMF and the capacitance transient energy is chosen as the fault line selection criteria according to the different proportion occupied by the low-frequency components. Finally, the fault location is determined based upon the comparison result with adjacent fault passage indicators' (FPI) waveform on the strength of the interaction between the distribution terminal unit(DTU) and the FPI. Moreover, the logic nodes regarding to fault line selection and location are newly expanded according to IEC61850, which also provides reference to acquaint the DTU or FPI's function and monitoring. The simulation results validate the effectiveness of the proposed fault line selection and location methods.

• 한국산학기술학회논문지
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• 제21권4호
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• pp.39-48
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• 2020

2017년 8월에 발생한 고창 전력시험센터를 시작으로, 현재까지 총 29건의 전기저장장치 화재가 발생하여 많은 재산피해가 보고되고 있다. 이에 대한 원인은 아직 정확하게 규명되지 않았으나, ESS(energy storage system)와 전력변환장치뿐만 아니라, 계통측 불평형 문제도 하나의 원인으로 고려되어야 할 것으로 보인다. 특히, 연계용변압기측의 순환전류가 자화전류에 영향을 미쳐, 의도치 않게 변압기의 철심이 포화되고 서지전압이 발생하여 ESS에 영향을 줄 수 있다. 따라서, 본 논문에서는 부하불평형에 의한 불평형전류 발생시, ESS 연계용변압기로 순환전류의 유입과 변압기 포화로 인한 서지전압 발생 현상을 해석하기 위하여, PSCAD/EMTDC를 이용한 배전용변전소, 연계용변압기 및 수용가부하로 구성된 배전계통의 모델링을 수행한다. 또한, 이러한 문제를 해결하기 위하여, 중성점 접지 저항기(neutral grounding resistor, NGR)를 통해 순환전류의 크기를 일정 값 이내로 저감시키는 방안을 제시하였다. 이를 바탕으로 시뮬레이션을 수행한 결과, 연계용변압기의 결선방식 및 철심구조에 따라 일정 값(10[A]) 이상의 순환전류가 발생하여, ESS에 전기적인 위해 요인이 될 수 있음을 알 수 있었고, 변압기 포화로 인해 2차측에 최대 3[pu]의 서지전압이 발생될 수 있음을 확인하였다.

• 보존과학연구
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• 통권28호
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• pp.121-147
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• 2007

A large variety of mineral pigments has been used for Korean paintings and it has known that organic pigments have been used together on the Buddhist painting and the portrait. Haehakbando-do, which is from Honolulu Academy Museum in the United States, 12-fold screen was commissioned by Court of the late Joseon Dynasty in order to pray for the King's longevity. Therefore, it seems that all material used including pigments were selected very carefully and a great deal of technical effort was gone into its process. The purposes of this research were to estimate the pigments and the contributory elements of each color used on Haehakbando-do, in accordance with the conservation treatment carried out by Gochang Conservation Institute throughout last year. Without extracting sample, property of pigment was measured by nondestructive method, X-ray spectral analysis, and by comparing with the data about ancient pigments. In spite of the limited range of pigment analysis by nondestructive method, it should be noted that this method would not cause damage to the cultural properites. White pigment was found in all colored parts except the background, so it can be suggested that white color was used as a grounding of other color pigments. This would be flake white[$2PbCO_3{\cdot}Pb(OH)_2$] as Pb was found. Pb was the only element could be found in yellow, however, it can be organic pigment like Gamboge as same as background. Red would be Cinnabar (HgS) as hydrargyrum (Hg) was detected. For the light purple in cloud, organic pigments were probably used since any element is not detected except for Pb, which is used for background. It is possible that green color is the mixture of Malachite[$CuCO_3{\cdot}Cu(OH)_2$] and Azurite [$2CuCO_3{\cdot}Cu(OH)_2$], which share Cu as their main element. Azurite[$2CuCO_3{\cdot}Cu(OH)_2$] was used for bluish pigments. Black is carbon compound. For gold, solid gold (Au) was detected. It shows that gold was gilded on the flake white background. Red painted on the frame of screen was identified as Cinnabar (HgS) and the gold pattern was solid gold (Au). The supporting leg of folding screen was made of brass because both copper and zinc were detected. In conclusion, white pigment was used as grounding of all colors of Haehakbando-do, and specific pigments were used for each color. Additionally, result from the analysis of several pigments shows that mineral pigment and organic pigment, or different mineral pigments were mixed to make various colors.