• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1774-1777
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• 1996

In this paper, applicability of SI-PD(switching impulse - partial discharge) testing method was put on an attempt as a newly proposed diagnostic method for the underground distribution power cable system in Korea. For this purpose, SI-PD testing equipment was designed, and tests were performed using artificial needle-type defects integrated into the 22.9 kV CN/CV cables in drder to prove its reliability. As a result, arc noises, generated from spark gap, were considerably decreased by use of a pneumatic switch immersed into oil, and artificial needle-type defects were well detected with impulse voltage level under $2U_0$. These results imply that it is likely possible to apply SI-PD measurement method as a the nondistructive test for the 22.9 kV CN/CV cable system in Korea.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.382-384
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• 1997

On-site partial discharge test by use of AC voltage has been considered not to be appropriate for the extruded power cable due to their large capacitance depending on their lengths. Therefore, it is proposed, in this work, to use switching impulse voltage of which the front time is set from 1ms to 10ms. This newly proposed method enables us to simulate the 1/4 period of power frequency at 60 Hz and to obtain similar effect of AC voltage test. Our tentative results show that 51 voltage is proved to be an alternative method, replacing AC voltage, by which partial discharge was well produced from the artificial defects integrated in 22.9kV distribution power cables.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.3
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• pp.135-141
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• 2004

A sterilizer equipment by using electrical energy has metrits that no process of chemical and no second environmental pollution, Also, the power conversion circuit for sterilizer equipment has mertis that are reducing switching loss for soft switching topology by using zero current and zero voltage switching, and miniaturizing size of equipment. The proposed power device which has lower output current than other devices is possible to be compacted in it's size reduced it's price if the proposed power device is used for power system. Therefore, it is adapted for both less power consumption and sudden power conversion

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.212-215
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• 2003

In this paper, a model pole transformer was designed to improve the reliability of pole transformers and its short circuit withstand strength was tested. The failure causes of the pole transformers which had been operated in the field were analyzed and several patterns of the causes were determined. A novel countermeasure was devised to prevent the failures of the pole transformers in advance. A model pole transformer was designed and made in accordance with the given specifications to strengthen the short circuit withstand capability and its characteristic was tested. As a result, the advanced performance of the model pole transformer was confirmed and novel techniques in manufacturing process was suggested. It is considered that all the methods employed in the developing process will be helpful to design and manufacture the pole transformers thus the reliability of pole transformers in distribution lines will be improved.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.4
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• pp.336-344
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• 2017

This paper presents the three-port DC-DC converter modeling and controller design procedure, which is part of the solid-state transformer (SST) to interface medium voltage AC grid to bipolar DC distribution network. Due to the high primary side DC link voltage, the proposed converter employs the three-level neutral point clamped (NPC) topology at the primary side and 2-two level half bridge circuits for each DC distribution network. For the proposed converter particular structure, this paper conducts modeling the three winding transformer and the power transfer between each port. A decoupling method is adopted to simplify the power transfer model. The voltage controller design procedure is presented. In addition, the output current sharing controller is employed for current balancing between the parallel-connected secondary output ports. The proposed circuit and controller performance are verified by experimental results using a 30 kW prototype SST system.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.4
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• pp.305-311
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• 2017

In this paper, the LLC resonant converter battery charger, using adaptive turn ratio scheme, is proposed to achieve high efficiency and wide range output voltage. The LLC converter high frequency transformer has an adaptively changed turn ratio by the auxiliary control circuitry. As a result, the optimal converter design with a large magnetizing inductance is easily achieved to minimize the conduction and the turn-off losses while providing widely regulated voltage gain capability to properly charge the Li-ion battery. The proposed converter operational principle and the optimal design considerations are illustrated in detail. Finally, several simulation results verify the proposed LLC resonant converter's effectiveness.

• Annual Conference of KIPS
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• 2000.10a
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• pp.23-26
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• 2000

정보기술이 발달하면서 자료의 흔적들이 체계화된 데이터베이스에 저장이 되고, 더불어 데이터베이스의 규모는 점점 커지고 있다. 데이터 마이닝은 이런 방대한 자료의 분석을 통해, 그 속에 숨어있는 의미를 찾는 과정이라고 볼 수 있다. 본 논문에서는 대용량 데이터베이스에 존재하는 여러 유용한 지식을 추출하는 방법으로서 데이터 마이닝을 분류화, 클러스터링, 요약규칙, 시간에 따른 분석 및 예측등으로 분류하여 요약, 제시하였고, 이렇게 추출된 패턴, 정보, 지식들의 유용성을 측정하는 지표를 정리하였다. 개발된 XM-Tool/Miner은 문제 중심적 마이닝 도구를 목표로 하였으며, 대표적인 마이닝 알고리즘을 적용하였고, 또한 사용의 편이성에 초점을 맞추었다. 더 나아가 데이터 마이닝 기법뿐만 아니라 데이터의 샘플링과 성능향상을 통하여 방대한 데이터로부터 다양한 지식탐사가 가능해지고, 발견된 규칙 또는 지식의 유용성 측정을 통하여 업무 분야의 특성에 따라 효과적으로 반영되며 의사결정 및 CRM 마케팅, 동향분석 및 예측 등에 유용한 정보를 추출하는 도구로 사용할 수 있을 것이다.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.7
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• pp.334-339
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• 2001

A silent type ozone generator using water surface has been studied and improved its ozone generation characteristics by the controlling the height of Taylor cone by installing a mesh electrode, a dielectric bed of glass beads in the just under th surface of the water. The current-voltage characteristics and characteristics of ozone generation quantity of the test system were investigated and discharge current oscillograms of the each cases of the mesh electrode and the beds were observed and compared each other to analyze the discharge conditions. The Taylor cone height could be the cause of the discharge bridge to decrease the ozone generation on the discharge spacing. In this study, the hight of Taylor cone could be reduced greatly by installing the mesh and the glass beads bed just under the water surface. Therefore a higher ozone generation also could be obtained.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.9
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• pp.936-941
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• 2004

In recent years, the rapid growth of portable electronic devices requires the high-energy density characteristics of batteries. Zinc air batteries have specific capacity as high as 820mAh/g. However, Zinc air batteries used for hearing aid applications only so far, because the atmosphere could affect it, and it has weakness in the rate capability. However, recent developments of electrode manufacturing technologies made us to overcome that weakness. And the efforts of applying zinc air batteries to portable electronic devices, especially in cellular phone application have been increased. In this paper, the effects of conducting material and polymer binder in cathode on the electrochemical characteristics were investigated. Our research team succeeded in producing 2.4Ah class zinc air battery for cellular phone application. Its volumetric energy density was 920 wh/l, and gravimetric energy density was 308 wh/kg. The volumetric energy density of our zinc air battery is two times higher than one of lithium secondary battery, and three times higher than that of alkaline manganese battery.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.204-206
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• 2002

For small capacity rectifier circuits such as these for consumer electronics and appliances. capacitor input type rectifier circuits are generally used Consequently. various harmonics generated within the power system become a serious Problem. Various studies of this effect have been presented previously. However. most of these employ switching devices, such as FETs and the like. The absence of switching devices makes systems more tolerant to over -load, and brings low radio noise benefits. We propose a power factor correction scheme using a LC resonant in commercial frequency without switching devices. In this method. It makes a sinusoidal wave by widening conduction period using the current resonance in commercial frequency. Hence, the harmonic characteristics can be significantly improved. where the lower order harmonics. such as the fifth and seventh orders are much reduced. The result are confirmed by the theoretical and expermental implementations.