• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.294-295
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• 2006

Varistor fabricated with ZnO nano-powder was studied about the characteristic of energy capability in this paper. ZnO nano-powder varistor were sintered in air at $1050\;^{\circ}C$. The electrical properties and residual voltage of ZnO nano-powder varistor were obtained. Our ZnO nano-powder varistor has about 3 times of electric field at varistor voltage as compared with commercial ZnO varistor fabricated with micro-powder. In the current impulse withstand test, our nano varistor has had better performance than micro varistor. To analysis energy capability take infrared images for pyrexia distribution of each varistor. ZnO Nano-powder varistor has shown much quick response property because of increasing effective cross-section.

• 한국전기전자재료학회논문지
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• 제22권8호
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• pp.659-664
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• 2009

This paper describes lightning impulse operating duty performance and temperature dependence of series gap type for transmission line arresters. The ageing parameters of lightning arresters are impulse current, moisture ingress, temperature ageing and so on. Especially it is important to estimate the change of electrical characteristics by lightning impulse current. In the discharge withstand test, total energy applied to the ZnO arrester each time is 4/10 ${\mu}s$, 30 kA. and in the operating duty test, the arrester has passed the test if thermal stability is achieved, if the residual voltage measured before and after the test is not changed by more than 5 %, and after the test reveals no evidence of puncture, flashover or cracking of the ZnO block. As a results, the residual voltage was in the range of 17.2${\sim}$20.3 kV and ZnO block bear up against at 2 shot of series impulse current of 30 kA. Also it was so excellent that the mechanical destruction does not occur at the 2 groups of 5 impulses current of 2/20 ${\mu}s$ 10 kA. According to the tests, it is thought that the ZnO arrester shows good stability with impulse current test. and it was found that the ambient temperature is increased resistive leakage current was increased in the range 47.3${\sim}$167.4 ${\mu}A$.

• 조명전기설비학회논문지
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• 제29권4호
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• pp.116-125
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• 2015

This paper presents experimental results obtained from actual installation conditions of surge protective devices (SPDs), with the aim of understanding the coordination of cascaded Class I and Class II SPDs. This paper also proposes effective methods for selecting and installing coordinating cascaded SPDs. The residual voltage of each SPD and the energy sharing of an upstream Class I tested SPD and a downstream Class II tested SPD were measured using a $10/350{\mu}s$ current wave. In coordinating a cascaded voltage-limiting SPD system, it was found that energy coordination can be achieved as long as the downstream SPD is a metal oxide varistor with a higher maximum continuous operating voltage than the upstream SPD; however, it is not the optimal condition for the voltage protection level. If the varistor voltage of the downstream SPD is equal to or lower than that of the upstream SPD, the precise voltage protection level is obtained. However, this may cause serious problems with regard to energy sharing. The coordination for energy sharing and voltage protection level is fairly achieved when the cascaded SPD system consists of two voltage-limiting SPDs separated by 3 m and with the same varistor voltage.

• 전자공학회논문지SC
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• 제46권6호
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• pp.21-27
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• 2009

휴대형 전자정보기기의 사용이 보편화되면서 고성능 전지를 개발하는 노력이 활발하게 진행되고 있는 등, 휴대형 장치에 전력공급 시간을 증대시키는 것이 중요한 문제로 대두되었다. 전력공급 시간의 연장을 위한 또 하나의 실용적 방법은 다중전지를 병렬 연결하여 사용하는 것이다. 본 논문에서는 다중전지를 사용하되, 단순한 병렬 연결이 아니라 전지 내부의 잔류 에너지를 재활용하는 새로운 발상을 소개하고자 한다. 이 방식은 전지의 사용에 따라 출력 전압이 기준값 이하로 떨어진 후라 할지라도 일정한 길이의 휴지시간을 경과하고 나면 잔류 에너지에 의하여 전압이 다시 일부분 회복되는 실제적 현상을 이용하려는 것이다. 잔류 에너지를 재활용할 수 있는 구체적인 방법으로서 전지선택형 다중전지 결합 방식을 제안하였다. 제안한 방식에 대하여 전지 방전특성을 실험적으로 측정하였으며, 알카라인 일차전지 한 개당 진력공급 시간을 1~2시간 정도 더 연장시킬 수 있음을 확인하였다.

• 한국전기전자재료학회논문지
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• 제18권8호
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• pp.720-723
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• 2005

We studied the quantitativity of the image sticking which is occured by the resicual DC in the fringe-electric field switching (FFS) mode. Actually, in the FFS mode driven by the strong fringe electric field, the asymmetric residual DC was formed in the bottom substrate. It made the impurity ion stick to the alignment layer such as polyimde layer. Thus, the differnece of the luminance existes after the stress check pattern is applied to the panel so that we can see the image sticking. This image sticking decreases as the residual DC value between specific patterns decreases. Therefore, it is necessary to control the residual DC for the FFS mode with the high image quality. It is possible to eliminate the image stiking when the extra pixel voltage is applied through the circuit tunning for reducing the difference of residual DC accroding to the panel position.

• 한국자기학회지
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• 제11권2호
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• pp.50-57
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• 2001

강자성 극박소재에 유기된 잔류응력을 검출하기 위하여 자기유도형 탐촉자(probe)를 설계·제작하였으며, 이를 장착한 잔류음력 평가시스템은 박판내에 유기된 잔류응력의 주응력 방향과 크기를 효과적으로 결정하여 준다. 이 시스템을 반도체 칩 팩키지(package)용으로 사용하는 Fe-42Ni계 lead frame 판재의 잔류응력 검출에 적용한 결과, 양호재 및 잔류응력과다 불량재에 대한 출력전압은 명확히 구별되었고, 잔류응력이 축적된 판재는 양호재와 비교하여 응력의 분포 및 크기에 있어 항상 차이를 나타내었다. 이러한 차이는 탐촉자에 투입하는 전류와 주파수의 함수로 잘 분해되어질 수 있음을 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.498-501
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• 2004

In this study, the threshold voltage and the response time of thermal stressed TN-LCDs showed the same performances on no thermal stressed TN-LCDs. There was little change of value in TN cells. Also, the transmittances of TN-LCDs on the rubbed PI surface were almost same while increasing thermal stress time. However, the thermal stability of TN cell was decreased by the high thermal stress for the long duration. Residual DC was decreased as the thermal stress increases. Especially, when TN cell was stressed more and more by heating, residual DC was changed a lot. As a result, the residual DC property of LCD in projection TV is affected very much by heating.

• 조명전기설비학회논문지
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• 제26권4호
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• pp.28-34
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• 2012

Installing surge protection devices for a low-voltage system is important to ensure the survival of electric or electronic devices and systems. If surge protection devices (SPD) are installed without consideration of the concept of lightning protection zones, the equipment to be protected might be damaged despite the correct energy coordination of SPDs. This damage is induced by the reflection phenomena on the cable connecting an external SPD and the load protected. These reflection phenomena depend on the characteristics of the output of the external SPD, the input of the loads, and the cables between the load and the external SPD. Therefore, the SPD has an effective protection distance under the condition of the specific load and the specific voltage protection level of SPD. In this paper, PSCAD/EMTDC software is used to simulate the residual voltage characteristics of SPD Entering the low-voltage device. And by applying a certain voltage level, the effective protection distances of SPD were analyzed according to the each load and length of connecting cable, and the effectiveness of SPD were verified.

• Journal of Magnetics
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• 제6권1호
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• pp.27-30
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• 2001

We present a new procedure to evaluate the residual life of 1Cr-1Mo-0.25V steel from reversible magnetic permeability. The method is based on the existence of first harmonics in the differential magnetization around the coercive force. The apparatus is based on the detection of the voltage induced in a coil using a lock-in amplifier tuned to the frequency of the exciting coil. Results obtained for the first harmonics and Vickers hardness on aged samples show that the peak interval of reversible permeability and Vickers hardness decrease as aging time increases. The correlation between Vickers hardness and the peak interval of the reversible permeability may be used to evaluate the residual life of 1Cr-lMo-0.25V steel, nondestructively.

• 한국물환경학회지
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• 제30권3호
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• pp.298-303
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• 2014

We measured by electrochemical method for TRC (total residual chlorine) in ocean. From the results of Au electrode used for working electrode through cyclic voltammetry test, we obtained charge in voltage ranged from 0.0V-1.0V, and analyzed correlations of charge for TRC. Reduction peak TRC was investigated to be approximately 0.65 V vs. Ag/AgCl, and in the case that salt concentrations and temperatures in ocean appeared different, charge was analyzed for being different in the same TRC. However, in the case that each condition was constant, charge was measured at highly correlations for TRC.