• 조명전기설비학회논문지
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• 제22권3호
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• pp.1-7
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• 2008

We have theoretically investigated the asymmetry effects on 10[Gb/s] optical duobinary transmitters from the viewpoint of the driving voltage ratios by computer simulations. For driving voltage ratios(=driving voltage/switching voltage) with smaller than 100[%], the transmission performance has been greatly affected by the asymmetry of the bandwidth of LPFs than that of the Mach-Zehnder Modulator driving voltage. On the other hand, for driving voltage ratios with 100[%], the transmission performance has been degraded by the asymmetry of the driving voltage and is not sensitive to that of the bandwidth of LPFs. For the transmission performance within 1[dB] power penalty under the asymmetry condition, the driving voltage ratio with 100[%] has performed better than the low driving voltage ratios.

• 전기학회논문지P
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• 제59권3호
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• pp.325-329
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• 2010

Capacitor has been used principally for the power factor compensation long ago. However now it does as passive filter to reduce harmonics of nonlinear load with reactor. Most of the customer's low-voltage feeder has been designed with approximately balanced and connected at the 3 phase four wire system. But voltage and current unbalance is appeared by the mixing operation of single or three phase load etc. The addition of reactor at the condenser may rise its terminal voltage. Voltage and current values above rating can act on electrical stress on the condenser. In this paper, we calculated and measured that voltage, current and capacity of condenser are changed under the voltage balance. We conclude that magnitude and deviation of phase voltage act on major point of electrical stress.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1233-1235
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• 2000

A new control method of three phase converter without measuring input phase-voltage and DC-link voltage is proposed. Input phase-voltage of these required voltages is estimated using EKF(Extended Kalman Filter) and DC-link voltage is estimated from the measured line currents and the estimated input phase-voltage. This control method is achieved without PLL(Phase Locked Loop) which senses the angle of input phase-voltage and DC-link voltage sensor. In addition, the proposed method controls high power factor and DC-link voltage utilizing the estimated phase angle. This paper describes the effectiveness of the proposed estimated algorithm through simulations.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.131-133
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• 2003

Voltage instability has been studied for some decade now. But, there is not generally accepted definition of voltage instability because of the complex phenomenon and the variety of ways in which it can manifest itself. Both IEEE and CIGRE have the respective definitions. The areas of voltage instability research arc the analysis, simulation and countermeasure of voltage instability. In this paper, we perform a dynamic simulation of voltage instability and voltage collapse using EMTP MODELS. The exponential load model is designed with MODELS and this load model is connected with test power system. The result shows the process of voltage change in time domain when the voltage instability or voltage collapse occurs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1202-1204
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• 2004

This paper propose the control algorithm for improving the power quality through the voltage compensation when source voltage is dropped. The algorithm signified occurrence of voltage drop in source voltage of each phase storing source voltage for two cycles using the concept of moving average and using the source voltage of last half cycle. If there are voltage drops in the source voltages, series active power filter compensates the differences between reference waveform and source voltage waveform. Therefore, voltage drop is compensated. It proposed series active power filter of three phases three lines to apply to the proposed algorithm and the presented experiment results verified logicality and effectiveness of the proposed algorithm.

• 대한전기학회논문지
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• 제43권5호
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• pp.693-702
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• 1994

This paper deals with direct voltage stability analysis using a power system energy function. The structure preserved energy function is proposed as an energy function for voltage stability analysis. With the use of the proposed energy function voltage collapse conditions are derived, which yields the exactly same results with the Jacobian matrix approach. The voltage collapse phenomenon is analyzed by several methods, which shows that all of the methods produce the same voltage condition. This study also investigates the voltage collapse dynamics by using the proposed energy function. As a result, it has been found that the voltage collapse can be classified into two categories: static and dynamic instablilties which have quite different behaviors. In addition a new method is presented to calculate the power capacity limit of transmission lines with respect to voltage stability. The proposed method is tested for a 2-bus sample system, which shows the characteristics of voltage collapse phenomenon via the energy function.

• Journal of Power Electronics
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• 제12권6호
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• pp.947-953
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• 2012

The latch-up immunity of the high voltage power clamps used in high voltage ESD protection devices is very becoming important in high-voltage applications. In this paper, a stacking structure with a high holding voltage and a high failure current is proposed and successfully verified in 0.18um CMOS and 0.35um BCD technology to achieve the desired holding voltage and the acceptable failure current. The experimental results show that the holding voltage of the stacking structure can be larger than the operation voltage of high-voltage applications. Changes in the characteristics of the stacking structure under high temperature conditions (300K-500K) are also investigated.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.227-230
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• 2001

A new control method of three phase converter without measuring input Phase-voltage and DC-link voltage is Proposed. Input Phase-voltage of these required voltages is estimated using EKF(Extended Kalman Filter) and DC-link voltage is estimated from the measured line currents and the estimated input phase-voltage. This control method is achieved without PLL(Phase Locked Loop) which senses the angle of input phase-voltage and DC-link voltage sensor. In additon, the proposed method controls high power factor and DC-link voltage utilizing the estimated phase angle. This paper describes the effectiveness of the proposed estimated algorithm through simulations.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 춘계학술대회
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• pp.696-698
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• 2012

본 논문에서는 기존의 Dickson's charge pump에 개선된 배전압 회로를 조합하여 구성된 새로운 전압증배기 회로를 소개한다. 기존의 charge pump로 얻어진 전압을 승압에 다시 사용하는 구조로 배전압기를 응용하여 전압증배를 가속화 하면서도 DMOS의 구조적 신뢰성을 저하하지 않도록 회로 구조를 제안하였다. 제안된 6단 전압증배기는 3V 전원으로 약 33V의 출력을 내며 6단 이상의 구성으로 고전압 증배도 가능하다. 제안된 회로의 성능을 평가하기 위해 Magna DMOS 공정을 이용하여 시뮬레이션 하였으며 이론적인 증배와 일치함을 보였여 최소한의 소자 사용으로 고전압 전압증배가 가능한 새로운 전압증배기를 제시하였다.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.865-873
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• 2017

Converter transformer is the key equipment of high voltage direct current transmission system. The solid suspending particles originating from the process of installation and operation of converter transformer have significant influence on the insulation performance of transformer oil, especially in presence of DC component in applied voltage. Under high electric field, the particles easily lead to partial discharge and breakdown of insulating oil. This paper investigated copper particle effect on the breakdown voltage of transformer oil at combined AC and DC voltage. A simulation model with single copper particle was established to interpret the particle effect on the breakdown strength of insulating oil. The experimental and simulation results showed that the particles distort the electric field. The breakdown voltage of insulating oil contaminated with copper particle decreases with the increase of particle number, and the breakdown voltage and the logarithm of particle number approximately satisfy the linear relationship. With the increase of the DC component in applied voltage, the breakdown voltage of contaminated insulating oil decreases. The simulation results show that the particle collides with the electrode more frequently with more DC component contained in the applied voltage, which will trigger more discharge and decrease the breakdown voltage of insulating oil.