• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.110-113
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• 2004

ZnO varistor ceramics which were fabricated with variation of added of $0.5{\sim}1.0mol%\;Co_3O_4$ sintered at $1150^{\circ}C$. In the specimen added $0.7mol%\;Co_3O_4$, sintered density was $6.03g/cm^3$ and electrical peoperties were superior to any other components. The nonlinear coefficient a was 83, and clamping voltage ratio was 1.35. But, endurence surge current in the specimen added $0.5mol%\;Co_3O_4$ was $7000A/cm^2$, and deviation of varistor voltage was ${\Delta}-3.23%$. As P.C.T and T.C.T environment test were succeed in all specimens, and deviation of varistor voltage in the specimen added $0.6mol%\;Co_3O_4$ was ${\Delta}-0.81%$. All specimens showed a good leakage current property in the High Temperature Continuous Load Test for 1000hr, at $85^{\circ}C$, and variation rate of the varistor voltage was ${\Delta}-2%$.

• 조명전기설비학회논문지
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• 제12권3호
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• pp.45-50
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• 1998

본 논문은 기존의 지중배전케이블의 준공시험으로 사용되고 있는 DC시험을 대체 하기 위한 초저주파 전원의 적용결과로서, 실험실에서 제작한 5m 길이의 실제 케이블의 칼흠집 결함과 침결함에 대해 초저주파 전원의 결함검출 능력을 평가하였다. 이 시험에서 초저주파 시험은 케이블 절연체 내부에 존재하는 결함부위에서 전기트리 개시는 어렵지만, 일단 전기트리가 개시되면 트리의 진전이 매우 빠르고 내부결함이 검출되지 않는 경우, 시험으로 인한 새로운 결함이 형성되거나 결함이 더 확대되지 않는 것으로 나타났다. 따라서 초저주파전원은 지중배전선로의 현장시험용으로 적용되기보다는 제조업체의 품질검사 확인용으로 사용하는 것이 효과적이라 판단된다.

• 전기학회논문지
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• 제56권5호
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• pp.869-875
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• 2007

Magnetic properties of electrical steel are, in general. measured by using Epstein frame or single sheet tester (SST). These methods, however, require very strict regulation of a specimen in its size and shape. thus, can not be easily applied to various types of specimen. On the other hand, a ring-test method, which measures only the isotropic properties, can be easily applied to most cases because it requires a toroidal-type specimen of arbitrary size. This method, especially, is considered as an unique available method for a bulk-type specimen. In this paper, a ring-test method is developed, and applied to the measurement of magnetic properties of a bulk-type electrical steel with a toroidal-type specimen. In the measurement, the magnetic properties and iron losses are measured and compared with each other at the both sinusoidal magnetic flux density and sinusoidal magnetic field intensity conditions under 0.2Hz and 60Hz alternating magnetic fields excitation. Through experimental measurements, a sinusoidal magnetic flux density condition is proven appropriate for the measurement of magnetic properties, including iron loss characteristics, of electrical steels.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
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• pp.2039-2040
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• 2006

Persistent current switch (PCS) system in NMR, MRI, MAGLEV and SMES has many advantages, such as uniformity and durability of magnetic field and reducing a thermal loss, which enable many superconducting application to operate effectively. This paper deals with fabrication and test of heater trigger persistent current switch using coated conductor (CC) which has high n-index, critical current independency from external magnetic field and adaptable selectivity of stabilizer. PCS system consists of magnet power supply for energizing current to a magnet, heater, switch and magnet using coated conductor tape. Finite element method (FEM) is used to simulate thermal quench (switching) characteristic and design heater trigger. With FEM simulation, optimal length of heater is calculated by temperature and time analysis. Fabrication of PCS system and test of heater trigger characteristic were performed and compared with simulation result. This paper would be the foundation of researches of superconducting switching application.

• 한국전기전자재료학회논문지
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• 제26권9호
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• pp.662-668
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• 2013

Reported here are results of the mechanical and electrical properties of both of intact and thermally degraded epoxy-coated copper busducts that are made by fluidized bed process. To elucidate and compare the properties mentioned above, electrical breakdown by thermal and water aging, v-t characteristic, bending test, impact test and cross cut test are carried out. Although the performance of electrical and mechanical properties are gradually decreased in increasing the severe conditions such as temperature, aging time, and so forth, sample C has a better performance in both mechanical and electrical properties.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1988년도 춘계학술대회 논문집
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• pp.43-45
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• 1988

Four W/Cu system(60wt%W-40wt%Cu, -0.lwt%Ni, -0.5wt%Ni, -0.lwt%C) and four WC/Cu system(60wt%WC-40wt%Cu, -0.lwt%Ni, -0.5wt%Ni, 0.lwt%C) electrical contacts were prepared by a press-sinter-infiltration process to compare with their properties. Hardness and electrical conductivity are proportional to the refractory metal(W or WC) properties and showed the effect of additives. Arc erosion trend of switch test is changed by current level. High currant test at 1kA showed a different crack formation pattern and erosion mode between W/Cu system and WC/Cu system contacts.

• Journal of Electrical Engineering and Technology
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• 제8권4호
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• pp.911-919
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• 2013

This paper reports the development of test bed with the energy recovering technique using two-step boost converter. The device is utilized for LDC aging test of Hyundai Motor's LPI AVANTE HEV in mass production. The developed power recycle type test bed is designed as 1.5 kW class to test up to the maximum load power of LDC and is also designed to supply scant power supply up to 500 W after power recycle. The theoretical design analysis and operational characteristics analysis results of test bed are reported, and its practicality and reliability are verified through the test result. Also, the finally developed test bed confirms approximately 79~85 % energy saving effect compared to the usual traditional aging test system.

• 전기저널
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• 5호통권65호
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• pp.36-41
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• 1982

• Transactions on Electrical and Electronic Materials
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• 제13권5호
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• pp.252-255
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• 2012

In order to characterize insulation properties of epoxy/micro-silica/nano-silicate composite (EMNC), long-term and short-term AC treeing tests were carried out undr non-uniform electric field generated between needle-plate electrodes. In a long-term test, a 10 kV (60 Hz) electrical field was applied to the specimen positioned between the electrodes with a distance of 2.7 mm in an insulating oil bath at $30^{\circ}C$, and a typical branch type electrical tree was observed in the neat epoxy resin and breakdown took place at 1,042 min after applying the 10 kVelectrical field. Meanwhile, the spherical tree with the tree length of $237{\mu}m$ was seen in EMNC-65-0.3 at 52,380 min (36.4 day) and then the test was stopped because the tree propagation rate was too low. In the short-term test, an electrial field was applied to a 3.5 mm-thick specimen at an increasing voltage rate of 0.5 kV/s until breakdown in insulating oil bath at $30^{\circ}C$ and $130^{\circ}C$, and the data was estimated by Weibull statistical analysis. The electrical insulation breakdown strength for neat epoxy resin was 1,763 kV/mm at $30^{\circ}C$, while that for EMNC-65-0.3 was 2,604 kV/mm, which was a modified value of 47%. As was expected, the breakdown strength decreased at higher test temperatures.

• 한국건설순환자원학회논문집
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• 제5권4호
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• pp.474-480
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• 2017

본 연구에서는 전기 임피던스 분광법을 이용하여 시멘트계 재료의 응결 시점을 평가하였다. 시멘트 페이스트 시편을 제작한 후 전기노드를 매립하여 전기 임피던스 응답 스펙트럼의 변화를 연속적으로 모니터링하였으며, 이와 동시에 간이단열시험을 통한 수화온도측정과 비카트침 시험을 함께 수행하였다. 전기 임피던스 분광법에서는 시멘트 페이스트의 수화와 동시에 컨덕턴스가 서서히 증가하는 경향을 나타냈다. 이후, 특정시점에 이르러 컨덕턴스는 급격히 감소하는 경향을 나타냈으며, 이후 또다른 특정시점에서 완만하게 감소하는 경향을 나타냈다. 이러한 특정 시점은 간이단열시험 및 비카트침 시험에 의해 측정된 응결시점과 부합하는 것으로 나타났다. 이를 통해 전기 임피던스 분광법을 이용하여 시멘트계 재료의 응결을 효과적으로 모니터링하는 것이 가능하리라 판단된다.