• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 제2회 학술대회 논문집 일렉트렛트 및 응용기술전문연구회
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• pp.21-24
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• 2000

Traction motors driven by several type inverters have been subjected to increasing demands for higher operating temperature, more demands for duty cycles, higher starting current, frequent voltage transients and finally severe environmental exposure. For applications to inverter duty, traction motors needs a special insulation system, which has characteristics of increased bond strength, lower operating temperature and higher turn-to-tum insulation. Also it needs major contributors to insulation life and reliability of motors, which more considered by temperature, voltage, frequency, rise time, pulse configuration, wire thickness and insulation materials. In this paper, to evaluate of reliability and expected life, it is analyzed the several stresses and their degradation mechanism on insulation system of AC traction motor.

• 대한기계학회논문집A
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• 제25권9호
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• pp.1452-1460
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• 2001

A new method of parameter determination in the fatigue residual strength degradation model is proposed. The new method and minimization technique is compared experimentally to account for the effect of tension-compression fatigue loading of spheroidal graphite cast iron and graphite/epoxy laminate. It is shown that the correlation between the experimental results and the theoretical prediction on the fatigue life and residual strength distribution using the proposed method is very reasonable. Therefore, the proposed method is more adjustable in the determination of the parameter than minimization technique for the prediction of the fatigue characteristics.

• 한국신뢰성학회지:신뢰성응용연구
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• 제11권3호
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• pp.267-279
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• 2011

LEDs have been used extensively in the mobile device, automobile, and general lighting because they are semi-permanent, long life, less power consumption, reliable and environmentally friendly. In this paper, the accelerated degradation test(ADT) for a general lighting 4W LED Lamp using external converter is considered. The conditions of ADT are high temperature and high humidity. We show that its life time is log-normally distributed with same parameters under both a normal condition and an accelerated condition, and also derive an accelerated factor.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.302-305
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• 1997

Treeing due to partial discharge(PD) is one of the main causes of breakdown of the insulating materials and reduction of tile insulation life. Therefore the necessity for establishing a method to diagnose the aging of insulation materials and to predict the breakdown of insulation has become important. From this viewpoint, our studies diagnose insulation degradation using the method of computer sensing system, which has the advantages of PD and acoustic emission(AE) sensing system. To use advantages of these two methods can be used effectively to search for treeing location and PD in some materials. In analysis method of degradation. using statically operator such as the center of gravity (G). the gradient of the discharge distribution(C), we have analyzed far tole prediction of life which we can be obtained the time, occurred of many pulse of small discharge amplitude.

• 한국세라믹학회지
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• 제24권3호
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• pp.251-256
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• 1987

The degradation of barium titanate ceramics was studied under the high AC electric field. At 150$^{\circ}C$, life time was measured as a function of grain size, controlled by varying sintering time at 1375$^{\circ}C$ and electrical properties, such as AC conductivity, capacitance and dissipation factor, were measured during degradation process. The life time decreased as grain size increased in the range of 2.44-8.23$\mu\textrm{m}$. The AC conductivity was remained constant and increased suddenly at the last stage of degradation process. The capacitance was slowly decreased and the dissipation factor was slowly increased as the degradaton progressed.

• Journal of Microbiology and Biotechnology
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• 제13권2호
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• pp.309-312
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• 2003

A bacterial strain NB01, isolated from wastewater, was found to utilize nitrobenzene (NB) as the sole source of nitrogen, carbon, and energy. The strain was classified as a member of a high G+C Gram-positive group and identified as Mycobacterium chelonae based on an analysis of its 16S rRNA gene sequence. The strain grew on NB with a concomitant release of about 63% of the total available nitrogen as ammonia, suggesting a reductive degradation mechanism. The optimal pH and temperature for degradation were PH 7.0-8.0 and $30^{\circ}C$, respectively. The cell growth was retarded at NB concentrations above 1.8 mM. The degradation of NB followed Michaelis-Menten kinetics within the tolerance range, and the $K_m$ and maximum specific removal rate for NB were 0.33 mM and $11.04\;h^{-1}$, respectively.

• Molecules and Cells
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• 제38권5호
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• pp.390-395
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• 2015

Degradation of chlorophyll (Chl) by Chl catabolic enzymes (CCEs) causes the loss of green color that typically occurs during senescence of leaves. In addition to CCEs, STAYGREEN1 (SGR1) functions as a key regulator of Chl degradation. Although sgr1 mutants in many plant species exhibit a staygreen phenotype, the biochemical function of the SGR1 protein remains elusive. Many recent studies have examined the physiological and molecular roles of SGR1 and its homologs (SGR2 and SGR-LIKE) in Chl metabolism, finding that these proteins have different roles in different species. In this review, we summarize the recent studies on SGR and discuss the most likely functions of SGR homologs.

• 한국인쇄학회지
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• 제29권3호
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• pp.97-104
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• 2011

The storing ability of information of optical disks directly depends on the physical property of recording unit cells. It means that the degradation of optical disks ultimately causes the loss of the physical and chemical properties of recording unit cells and leads also information, too. We investigated the degradation and life time of optical disks which tell us the longevity of the preservation of information. Optical disks were aged using the accelerated aging system and studied by optical reflectivity spectroscopy and atomic force microscopy(AFM), and the preservation environment of electronic media in National central library of Korea also were analysed. Results show that the double reflective coated optical disks have good preservation of recording information but revealed some deformation of dye area in the AFM images. It means that we should include the mechanical and chemical degradation of the optical disks in the life time expectation evaluation.

• 생명과학회지
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• 제5권1호
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• pp.8-19
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• 1995

The Optimal condition for degradation of crystal violet and other triphenylmethane dyes by Citrobacter sp. SK-3 isolated from the activated sludge of dye manufacturing factory was investigated. The optimal culture medium for the degradation of triphenylmethane dye was composed of minimum inorganic salt medium supplemented with 0.5% galactose, 0.1% beef extract, with the initial pH of 8.0 to 9.0. Under this condition, Citrobacter sp. SK-3 degraded 200 ppm of crystal violet completely within 24 hours. Citrobactre sp. SK-3 also degraded efficiently malachite green, pararosaniline, brilliant green, methyl violet, basic fuchsin and methyl red. Analysis of the degradation products of crystal violet through this layer chromatography and high performance liquid chromatography indicated that the methyl groups bound to crystal violet backborn were gradually demethylated to pentamethyl-, tetramethyl- and trimethylpararosaniline.

• 한국화재소방학회논문지
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• 제33권2호
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• pp.114-123
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• 2019

본 논문은 IV 및 HIV 절연전선의 가속열화에 따른 절연피복의 성능변화에 관한 연구이다. IV 및 HIV 절연전선의 절연열화를 가정하기 위해 가속수명시험 모형 중 아레니우스 방정식을 이용한 가속수명시험을 진행하였고, 등가수명 0년, 10년, 20년, 30년, 40년 실험시료를 제작하였다. IV 및 HIV 절연전선의 가속열화가 진행됨에 따라 최대인장하중은 커지는 반면, 절연전선의 신장률, 파단시간, 유연성이 점차 감소되는 것으로 나타났다. 추가적인 주사전자현미경을 이용한 등가수명별 절연전선 표면 분석 결과 가속열화가 진행됨에 따라 시료 표면에 결정형 구조 및 천공 등의 현상이 발생되어 노후화에 따른 절연열화가 진행 될수록 절연체의 기계적 특성이 감소되는 것으로 나타났다. 따라서 절연성능 저하에 따른 전기화재 위험성을 사전에 예방하기 위해선 건축물 내에 설치되는 절연체의 성능저하를 고려한 제도적인 절연전선의 교체 및 보수시기의 마련이 필요할 것으로 생각된다.