• Journal of Conservation Science
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• v.34 no.6
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• pp.459-470
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• 2018

Cellulose nitrates were used for folklore artifacts(ornamental beads and pipes in hatstrings, frames of eyeglasses, ornamental eyeglass cases, headband ornaments, and jeogori buttons) between the 19th and 20th centuries; however, they are susceptible to cracking, crazing, embrittlement, and crumbling due to deterioration. To consolidate and adhere deteriorated cellulose nitrate folklore artifacts, water-soluble acrylic emulsion adhesives were investigated. For consolidation, Plextol D 498, which has the lowest viscosity in low concentrations, was used. In adhesive films whose glass transition temperature(Tg) is lower than room temperature, the tensile stress and modulus decreased and the strain increased; therefore, the flexibility was high. The Plextol D 498 and Plextol D 498 and Dispersion K 52 films maintained their adhesiveness and flexibility after artificial-sunlight-accelerated ageing, and Plextol D 498 and Dispersion K 52 films hardly caused yellowing. Plextol D 498 was the most stable for accelerating ageing. A low concentration of Plextol D 498 emulsion resulted in the best permeability on the surface of cellulose nitrate, compared with other acrylic emulsions. To prevent ornamental hatstrings from cracking, crazing, embrittlement, and crumbling, a Plextol D 498 emulsion was used. After applying low concentrations(1%, 3%) of the emulsion to consolidate the fragments and high concentration to adhere the fragments, the ornamental hatstrings were protected from crumbling by deterioration, and their fragments were well-adhered. To preserve it from deterioration by oxygen and humidity, the treated ornament was sealed with an oxygen-barrier film using a low-humidity oxygen scavenger.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1753-1755
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• 2001

최근 전력설비의 절연을 위해 고분자 재질의 절연물이 광범위하게 사용되고 있다. 이러한 고분자 재료는 현재까지 주로 사용되어 온 세라믹 재질과는 달리 환경에 의한 열화를 동반하게 된다. 최근에 현장에 적용되기 시작한 고분자 재질의 절연물에 대한 장기 열화특성을 평가하기 위한 연구들이 다수 진행되고 있는 것도 이러한 이유 때문이다. 피뢰기의 경우에도 기존의 세라믹 애관을 고분자 재질의 애관으로 대체하기 시작하여 일부 제품들이 현장에서 우수한 특성을 보이는 것으로 보고되고 있으나 장기신뢰성에 대해서는 명확하지 않은 상태이다. 본 논문에서는 국내에서 제작되어 현장사용중인 폴리머 피뢰기를 발취하여 사용기간중 성능상의 변화를 분석하고 가속열화시험을 통해 성능의 변화를 관찰하고자 하였다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1215-1215
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• 2015

본 연구에서는 상용 XLPE 절연체에 ES(한전)의 장기과통전 시험 기준을 참고하여, 가속 열 열화 하였고, 열화 전/후의 절연특성을 비교하기 위하여 VLF(0.1Hz) 내전압 파괴시험을 수행하였다. 또한, 그 결과를 Weibull plot하여 절연특성을 통계적으로 비교 및 분석하였다.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.1
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• pp.24-33
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• 1997

In this paper, aging of insulating oil in pole transformer has been studied by performing accelerated thermal aging test. Dissolved gases were extracted by air bubbling method. Concentration of dissolved gases were modified by extraction ratio of each gases in insulting oil. Aging of insulting materials were proceeded by thermal degradation and oxidation reaction. Both of the reactions followed zeroth order kinetics. Formation rate equations for hydrocarbons, carbon oxides, and hydrogen were derived. It was conformed by gas analysis and UV-visible spectrophotometric method that iron core and copper coil in pole transformer act as catalyst during the aging process.

• Proceedings of the Korean Reliability Society Conference
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• 2006.05a
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• pp.331-334
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• 2006

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05e
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• pp.31-34
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• 2003

폴리머 애자의 장기성능예측을 위하여 많은 수단과 측정방법이 연구되어 왔다. 그러나 폴리머 애자에 있어서 성능저하는 대부분 하우징 재료의 열화에 기인되고 있어 예측 및 진단목적의 연구가 하우징 재료의 가속열화에 초점이 맞추어져 있다. 폴리머 애자는 초고압 절연성능과 기계적 강도가 우수하여 송배전 설비에 많이 사용되고 있지만 애자의 형상과 장기성능과의 관계가 정량적으로 규명되어 있지 않아 개발하는 회사는 물론 사용하는 전력회사가 함께 어려움을 가지고 있다. 폴리머 애자의 형상이 폴리머 애자의 장기 성능에 어떻게 영향을 주는 지를 비교분석하고 평가하는 연구가 필요한 시점이다. 본 연구에서는 규칙 교대 갓, 불규칙 교대 갓의 폴리머 애자를 조립방식으로 제작하고, 규칙 교대 갓의 폴리머 애자를 일체형 진공사출 방식으로 제작을 하여 건조섬락전압, 주수섬락전압, 오손섬락전압을 측정하였다. 오손섬락전압은 주수섬락에 비하여 60% 정도 감소함을 보였고 불규칙한 교대 갓의 폴리머 애자의 경우 특성의 편차가 크게 나타났다. 폴리머 애자의 경우 소재의 우수한 특성도 중요하지만 형상적인 인자도 중요한 설계요소이므로 최적화 방안이 요구된다.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.10
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• pp.479-488
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• 2001

The effects of accelerated Ultraviolet (UV) radiation on High temperature vulcanized (HTV), Room temperature vulcanized (RTV) silicone rubber and two types of ethylene propylene diene terpolymer (EPDM) used for composite insulator were inverstigated by hydrophobicity class (HC), surface voltage decay after corona charging, SEM-EDS, FTIR and XPS. The contact angle in two kinds of silicone rubber was scarcely change, but EPDM occurred to the loss of hydrophobicity followed by surface cracking and chalking. The surface voltage decay on UV-treated silicone rubber and EPDM showed a different decay trend with UV treatment. EDS and XPS analysis indicated that the oxygen content increased with UV treatment time in all samples. For silicone rubber, the oxidized groups of inorganic silica-like structure increased with UV treatment time. The oxidized carbon of C=0, O=C-O in EPDM increased. These oxidized surface for each material had different electrostatic characteristics, so deposited charges were expected to have different impacts on their surface hydrophobicity. The degradation mechanism based on our results was discussed.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.93-96
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• 2007

Recently, much attentions have been paid on the commercialization of PEMFC, especially for the applications of residential and portable. In order to achieve the early commercialization of PEMFC, thee are two hurdles to overcome. One is cost down and the other is improvement of durability of the system components. Numerous companies have tried to reduce the production cost and the main research topics have been changed from performance to durability improvement. In this work, acceleration test were performed to find and evaluate the main reason of degradation of the MEA(membrane-electrode assembly) which is one of the core component of the PEMFC system. Based upon the test results, a way to make durable MEA was suggested. Acceleration tests were made by applying high voltage of 1.2V to the several kinds of single cells to increase the growth of catalyst particles. Cell performance, ac-impedance and electrochemically active area measurements were made atfter every 8 hours of acceleration test. Degradations of catalyst and membrane were examined by SEM, TEM and XRD. Obtained results were discussed in terms of structural stability and loss of catalyt and ionomers in the electrode layer. In addition, the way to make highly durable MEA was suggested.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.443-446
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• 2009

In this study, a series of degradation test for structural adhesives was performed to investigate the possibility of replacement of the alternative adhesives to the conventional adhesives. Four types of the adhesives were exposed to combined environmental conditions over 1000 hours at an accelerated aging tester, which can simulate natural weather conditions such temperature, moisture and ultraviolet. Mechanical and chemical properties of the adhesives were evaluated through material testing system and FT/IR spectrometer. According to the results, the conventional adhesives can be replaced by the alternative adhesives because the alternative adhesives were more stable to environmental conditions rather than the conventional adhesives.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.100-103
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• 2003

The primary insulation system used in an oil-filled transformer is kraft paper, wood, porcelain and oil. Modern transformers use paper that is chemically treated to improve its tensile strength properties and resistance to aging caused by immersion in oil. But these insulation papers are mainly aged to thermal stress. Over the course of the insulation paper and oil's life it is exposed to high temperatures, oxygen and water. Its interaction with the steel of the tank and core plus the copper and aluminium of the windings will eventually cause the chemical properties of the oil to decay. High temperature have an effect on mechanical strength of cellulous paper using the layer insulation. We made two aging cell in which thermal aging tests of insulation papers and mineral oil are conducted. It is measured dielectric strength, number of acid, moisture, etc. of insulation paper and oil aged in the aging cells.