• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기설비전문위원
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• pp.97-99
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• 2004

Liquid-immersed pole transformers have utilized an insulation system consisting of natural cellulose-based materials and mineral oil for many years. If the transformers are installed with the abruptly changing load over limitation, its insulation materials are apt to unexpected aging with high temperature. Therefore we have been conscious of developing a transformer that is more thermally stable then conventional types. To measure temperature distribution in the winding of conventional and newly designed transformers, temperature sensors were installed fordirect reading of oil and conductor temperatures at transformers. And we conducted accelerating aging test for these transformers. The measuring data had made use of the design to hybrid insulation system. Also we could find the possibility of this insulation system to apply in pole mounted transformers.

• 전기학회논문지P
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• 제60권1호
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• pp.45-47
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• 2011

Recently, research works for electrical properties on the elastic epoxy have been also progressing to diagnose insulation materials by development of measure technology. The epoxy which specially applied for high voltage instruments have required for the electrical, mechanical and thermal properties. Nanocomposites were made from insulating material epoxy resin using for power transformer as varying g amount of addition of SiO2, we found the change of physical characteristics of nanocomposites by using SEM and XRD. To investigate the electrical properties according to the amount of addition and temperature, tested insulting breakdown in silicon oil. As the result of insulting breakdown testing, the insulting breakdown strength increased according to change of the amount of addition.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.198.1-198.1
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• 2014

Many efforts have been devoted on chemical modification of graphene layer to modulate its electrical properties. In the previous report, laser irradiation on the CYTOP(perfluoropolymer) doped graphene layer induces chemical modification of it, resulting in the insulating I-V characteristics. While the results strongly denoted C-F bond formation after irradiation, the detailed process of photo-induced chemical change is not known yet. To probe this, we utilized synchrotron based SPEM (scanning photoelectron emission spectroscopy) in NSRRC, Taiwan. We irradiate the sample by photon of 614 eV in a stepwise manner as a function of time. As photon irradiation increased, difluoride moieties in the CYTOP was broken, and then formed mono-fluoride with carbon atoms consisting graphene layer.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권7호
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• pp.340-345
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• 2001

Because they have superior insulating properties and lower in price than their ceramic equivalents, polymeric insulators have been used in outdoor insulators. But polymeric insulators mainly using in an heavy contamination area of outdoor could be easily attached to contaminants such as salt and by-products of industrial processes. To understand its effect on contaminants adhered to these insulators, we dismounted polymeric insulators adhered contaminant in the field, and evaluated its electrical characteristics, CA, and ESDD. We also manufactured slurry mixed by some kaolin and salt for the artificial contamination test and measured the degree of contaminant, AC leakage current for these contaminated samples. Consequently, the adhered contaminants to its surface is likely to be affected the performance of insulation.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.489-489
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• 2011

The effect of Si quantum dots for solar cell appications was investigated. The 5 ~ 10 nm Si nanoparticle was fabricated on p-type single and poly crystalline wafer by magnetron sputtering and laser irradiation process. Scanning electron microscopy (SEM), atomic force measurement (AFM) and transmission electron microscopy (TEM) images showed that the Si QDs array were clearly embedded in insulating layer ($SiO_2$). Photoluminesence (PL) measurements reliably exhibited bandgap transitions with every size of Si QDs. The photo-current measurements were showed different result with size of QD and number of superlattice.

• 한국의류학회지
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• 제18권2호
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• pp.244-251
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• 1994

The purpose of this study was to analyze conductive convective and radiative heat transfer characteristic of the nonwovens were studied by measuring thermal conductance at atmospheric and low air pressure. The results obtained were as follows . 1) As thickness of air layer Increased, overall heat transfer was decreased by reducing conductive and radiative heat trasfer. 2) The conductive and convective heat trasfer by air were in the range of 79~8971 of overall heat transfer. 3) As thickness of nonwoven increased for a given solidity, overall heat trasfer was decresed by increasing total thickness of air layer and by reducing conductive and radiative heat transfer. 4) For a given weight, increasing thickness is more effective than increasing solidity.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
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• pp.37-38
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• 2000

The ZnS:Tb thin-film electroluminescent devices were grown by atomic layer deposition with utilizing single-layer aluminum oxide and/or multilayered tantalum aluminum oxide, $Ta_xAl_yO$, as upper and lower insulating layers. These devices were investigated in terms of the luminescent and electrical characteristics. From this analysis, the devices using the $Ta_xAl_yO$ instead of $Al_2O_3$ were observed to have a lower threshold voltage for emission due to the higher relative dielectric constant of $Ta_xAl_yO$ insulators than that of the $Al_2O_3$ device. And there was a large amount of dynamic space charge generation in the phosphor of the device with the $Ta_xAl_yO$ insulators seemingly due to electron multiplication such as trap ionization.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.810-812
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• 1988

This paper is to investigate dielectric properties and new fabrication method of Glass-Cloth/Epoxy composite materials. According to the results of this paper, gelling point temperature is affected significantly on the ambient temperature. And Tan${\delta}$ characteristics of Glass-Colth/Epoxy composite materials is also affected significantly on the state of interior void of glass cloth and interface coupling between epoxy resin and glass cloth.

• E2M - 전기 전자와 첨단 소재
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• 제9권9호
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• pp.942-948
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• 1996

Electrical properties such as surface flashover discharge and discharge degradations of insulating materials for superconducting cable have been investigated. It is found that the surface voltage is proportional to $l^{0.7}$ (l: discharge length) in liquid helium (LHe). V-t characteristic in LHe was a n=5.5 that was less than liquid nitrogen (L $N_{2}$). After applied AC voltage, the surface condition of polymer films was observed non-eroded areas and eroded areas. The eroded area is depending on the applied voltage. In case of LHe, the crack was observed.d.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
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• pp.106-109
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• 2001

In this paper, we have investigated the degradation of shed materials of outdoor insulators by UV-radiation by using corona-charging and XPS analysis. The accumulated charges on polymeric surface having intrinsic hydrophobic property have a negative impact on retaining its hydrophobicity. Therefore, shorter decay times of surface charges are preferred. The surface voltage decay on UV-treated silicone rubber and EPDM show a different decay trend with UV treated time. From the XPS analysis, the oxidized groups of silica-like structure in silicone rubber increase with UV treatment time. For EPDM, the oxidized carbon groups of C=O, O=C-O increase as elapse of UV radiation time. These oxidized surface for each material have different electrostatic characteristics, so deposited charges may be expected to have different impacts on their surface hydrophobicity. The degradation mechanism based on our results is discussed.