• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 유기절연재료 방전 플라즈마연구회
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• pp.6-10
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• 2003

In our country, the housing materials of polymeric outdoor insulators have mainly been used EPDM or silicone rubber. EPDM housing materials had been widely used in the field for the first time. The reason why silicone has the high cost of production. But recently, most of the manufacturers that newly developed polymeric insulators make its choice of silicone housing. EPDM showed a good resistance to tracking. We compared the various characteristics for EPDM and silicone insulators that have similar type and design. Silicone insulators have more performance in flashover voltage test and leakage current measurement because of a good water repellent than EPDM ones. Also, the property of EPDM compared with silicone insulators greatly decreased after aging test in combined acceleration ageing facilities for 1000 hours.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.94-94
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• 2010

The result was estimated on the fractal characteristics as possibilities of identification of manufacture state for long period stabilities. At the second, the dangerous area was easily found to the recurrent phenomena of FD output. However, such area is very difficult to analysis of mechanism and to predict the lifetime in present state, it is possible to discriminate by means of data accumulation.

• 한국군사과학기술학회지
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• 제9권1호
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• pp.13-23
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• 2006

A propellant mainly consisting of nitric ester including nitrocellulose and nitroglycerine is characteristic of being decomposed naturally. And this phenomenon is known as being affected mostly by its storing temperature and humidity. In this research, the effect of storing temperature and humidity on self life has been studied by measuring the contained quantity of residual stabilizer of propellant KM30Al, which are parts of 155MM propelling charge K676 and K677; the method for the measurement is acceleration aging test, and decomposition reaction equation, Eyring Equation and Berthlot Equation were used for the calculation. As result of this study, it was found that the storing temperature influenced seven times as large as the storing humidity upon the self life of the propellant KM30Al, Furthermore, especially in the high temperature region, the storing temperature had a dominant effect on the self life.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1010-1015
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• 2009

Rail-pad is an important and readily replaceable component of a railway track, as it is the elastic layer between the rail and the sleeper. Characteristics and useful lifetime prediction of rail-pad was very important in design procedure to assure the safety and reliability. In order to investigate the useful lifetime, the accelerate test were carried out. Accelerated test results changes as the threshold are used for assessment of the useful life and time to threshold value were plotted against reciprocal of absolute temperature to give the Arrhenius plot. By using the acceleration test, several useful lifetime prediction for rail-pads were proposed.

• 한국군사과학기술학회지
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• 제8권1호
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• pp.14-24
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• 2005

A propellant mainly consisting of nitric ester including nitrocellulose, nitroglycerine and nitroguanidine is characteristic of being decomposed naturally. And this phenomenon is known as being affected mostly by its storing temperature. In this research, the effect of storing temperature on self life has been studied by measuring the contained quantity of residual stabilizer of propellant KM30A1, ignition powder and combustible cartridge case, which are parts of 155MM propelling charge K676 and K677; the method for the measurement is acceleration aging test, and decomposition reaction equation and Berthlot Equation were used for the calculation. The result of this research shows that propellant KM30A1, ignition powder, combustible cartridge case in order of decreasing self life, and the self life decreases to 1/3 as the temperature increases by $10^{\circ}C$.

• Structural Engineering and Mechanics
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• 제17권5호
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• pp.727-734
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• 2004

An uncoupled computational model for analyzing the hygrothermal dynamic response of composite laminates has been developed. The constitutive equations, expressed in an integral form, and involving relaxation moduli are adopted, to describe the non-aging hygrothermorheologically simple materials. A Prony series represents the relaxation moduli is exploited in order to derive a recursive relationship, and thereby eliminate the storage problem that arises when dealing with material possessing memory. The problem is formulated in a descritized variational form. Mindlin and higher order finite elements are employed for spatial descretization, while the Newmark average acceleration scheme is exploited for temporal descritization. The adopted recursive formula uses only the details of the previous event to compute the details of the current one. Numerical results of the displacement fields of both thin and thick viscoelastic laminates problems are discussed to show up the effectiveness of Mindlin and higher-order shear theories.

• Corrosion Science and Technology
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• 제5권5호
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• pp.177-180
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• 2006

The anticorrosive performance of epoxy coating was examined by using the hygrothermal cyclic test and the degradation mechanism of the coating was investigated by using the AC impedance method. The relationship between the results obtained from different tests was studied. It was revealed that the hygrothermal cyclic test can be used as an effective acceleration test for the degradation of organic coating. It was also found in hygrothermal cyclic test that the epoxy coatings have the resistance to stresses at some extent. The degradation of organic coating seems to be caused by the decrease of resistance of coating and the increase of both capacitance and free volume in the organic coating.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(I)
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• pp.86-91
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• 2002

Glass/phenolic composite laminates have been used in the field of non-flammable light rail transit and their applications have expanded more widely. Low velocity impact tests have been used to evalute the effect of temperature and acceleration aging on low velocity impact response of phenolic matrix composites reinforced with woven E-glass fabric. The damage of matrix cracking and delamination are suddenly reduced the compressive strength after impact. The damage area increases with increasing temperature and impact energy. UT C-scan is used to determine damage areas by impact loading. Therefore, all this observations indicate reduced impact damage resistance and damage tolerance of the laminates at elevated temperature.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.104-111
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• 2006

The non-linear properties of rubber material which are described as strain energy function are important parameter to design and evaluate of rubber spring. These are determined by material tests which are uni-axial tension and bi-axial tension. The computer simulation using the nonlinear element analysis program executed to predict and evaluate the load capacity and stiffness for chevron spring. In order to investigate the heat-aging effects on the rubber material properties, the acceleration test were carried out. Compression set results changes as the threshold are used for assessment of the useful life and time to threshold value were plotted against reciprocal of absolute temperature to give the Arrhenius plot. By using the compression set test, several useful life prediction for rubber material were proposed.

• 한국기록관리학회지
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• 제4권2호
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• pp.1-22
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• 2004

상지(桑紙)는 우리나라에서 많이 사용된 종이였음에도 불구하고 문헌에 그의 원료에 대한 기록이 거의 없다. 양잠의 원료로서의 중요성 때문이기도 하지만 닥나무와 비슷한 형태때문일 것으로 생각된다. 특히 양잠에 유리한 수종(樹種)으로 개량되면서 종이의 원료로서의 중요성을 점차 잃어서 현재는 생산되지 않는 전통종이 가운데 하나다. 본고에서는 뽕나무의 인피를 사용하여 전통상지(傳統桑紙)를 만들고 저지(楮紙)와 함께 그 물성(物性)을 비교하여 보았다. 그 결과 섬유의 형태면에서는 섬유의 길이와 넓이의 비율이 475이며, 화학적 조성에서도 리그닌의 함량이 닥나무보다 적었으므로 종이의 원료로서 매우 우수하였다. 종이의 물성도 저지와 큰 차이가 없었다. 또 종이의 보존성을 시험한 결과 $105^{\circ}C$로 72시간, 144시간을 가열한 환경에서는 상지가 저지와 비교하여 불리하였으나, 자외선이 24시간, 100시간, 200시간 조사된 환경에서는 시간이 경과될수록 변화의 폭이 적었다. 즉 오랜기간이 경과될수록 상지는 덜 노화되며, 외관상으로도 열화가 많이 진행되지 않는 훌륭한 종이임이 밝혀졌다. 특히 실험에 사용한 상피(桑皮)가 개량종임을 감안한다면, 조선조나 그 이전에 만들어진 상지는 더 품질이 좋았을 것으로 사료된다.