• 한국세라믹학회지
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• 제56권1호
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• pp.1-23
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• 2019

Dielectric materials with inherently high power densities and fast discharge rates are particularly suitable for pulsed power capacitors. The ongoing multifaceted efforts on developing these capacitors are focused on improving their energy density and storage efficiency, as well as ensuring their reliable operation over long periods, including under harsh environments. This review article summarizes the studies that have been conducted to date on the development of high-performance dielectric ceramics for employment in pulsed power capacitors. The energy storage characteristics of various lead-based and lead-free ceramics belonging to linear and nonlinear dielectrics are discussed. Various strategies such as mechanical confinement, self-confinement, core-shell structuring, glass incorporation, chemical modifications, and special sintering routes have been adopted to tailor the electrical properties and energy storage performances of dielectric ceramics. In addition, this review article highlights the challenges and opportunities associated with the development of pulsed power capacitors.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.877-878
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• 2009

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1653-1655
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• 2003

The purpose of this paper is to evaluate the effects of pre-formed space charge by negative DC voltage on partial discharge(PD) patterns of XLPE. We have suggested a modified pulsed electro-acoustic method and demonstrated that the PD patterns are strongly influenced by the pre-formed space charge distributions, which are hardly disappeared up to AC 8kV in electrode configuration including air gap between XLPE layer and electrode.

• Journal of Electrical Engineering and information Science
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• 제3권3호
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• pp.316-321
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• 1998

In recent years, concern has been raised about the technique of controlling electrical breakdown by using laser in many fields. Especially, laser has attracted much attention in the Electro-Discharge Macining(EDM) because of its many merits. Therefore, this research has been performed to obtain fundamental data relevant to discharge processing by using a pulsed Nd:YAG laser. The experiments of laser-guided dc discharge by laser radiation have been carried out at low air pressure ranging from 0.2 to 20 torr. The minimum laser-guided dc discharge voltage V\ulcorner at the given pressures P and distances D between an anode and a cathode was measured. It is found that the minimum laser-guided dc discharge voltage is much lower than the natural discharge voltage V\ulcorner\ulcorner, and the values of V\ulcorner and V\ulcorner as a function of P.D has a similar tendency. The laser output energy Eout decreases with input pulse duration tp increasing, and the more the value of tp increases, the higher that of V\ulcorner is obtained because the number of photons during the discharge time N decreases with t\ulcorner increasing. There is the time lag frequently when the discharge by laser radiation is misguided under the condition of the applied voltage less than V_G.min.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1905-1907
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• 1997

The experiments of laser-guided de discharge were carried out by using pulsed Nd:YAG laser radiation at low air pressure ranging from 0.3 to 20 torr. The minimum laser-guided de discharge voltages($V_{MD}$) at given pressure and distances between anode and cathode electrode were obtained. In order to generate TEM(transverse electromagnetic waves) modes, a pinhole was installed between a rod and a half mirror, and its diameter was adjusted from 6mm to 1.7mm. And then, we investigated the characteristics of laser-guided de discharge corresponding to different TEM modes. As a result, it was found that $V_{MD}$ at $TEM_{00}$ mode was lower than $V_{MD}$ at multimodes.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.335-340
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• 2004

On a liquid propellant PPT, the discharge processes that discharge was initiated and plasma was accelerated was observed by using a ultra high speed camera. Liquid propellant PPT is a pulsed plasma thruster using liquid as propellant. Our past study showed the successful operation of liquid propellant PPT and the thruster showed high specific impulse. However, its acceleration mechanism has not been clarified. In this study we observed the plasma acceleration processes in order to deepen our understanding of the acceleration mechanism.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1837-1839
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• 2003

Recently deep interests have been paid on the effective generation of ozone, which has been widely used for water treatment, deoderization, color removal and chemical processing of exhausted smoke. The silent discharge reaction has been proposed as the most effective in the many ozone generation methods by electric discharge, because silent discharge excel others in the condition of high ozone generation yield and low power consumption. In this paper, ozone water generated system measure with silent discharge characteristics and pulsed power supply.

• 반도체디스플레이기술학회지
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• 제18권2호
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• pp.17-22
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• 2019

The method of electrical discharge machining (EDM), one of the processing methods based on non-traditional manufacturing procedures, is gaining increased popularity, since it does not require cutting tools and allows machining involving hard, brittle, thin and complex geometry. This present investigation details the determination of optimum process parameter to attain the better machining performance in EDM of AISI 4340 steel with graphite as a tool electrode. The experimental combinations are planned and analyzed by Taguchi's design of experiments approach. To predict the optimal condition, the experiments are conducted by using Taguchi's L27 orthogonal array. The influence of process variables such as discharge current, pulse on and pulse off time, voltage and spark speed were investigated to control the various desired performance measures such as surface roughness. Analysis of Variance (ANOVA) has to be performed to know the magnitude of each factor. Investigations indicate that the surface roughness is strongly depend on pulsed current.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1609-1611
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• 2001

A large cross-section pulsed electron beam generator of cold cathode type has been developed for industrial applications, for example, waste water cleaning, flue gas cleaning, and pasteurization etc. The operational principle is based on the emission of secondary electrons from cold cathode when ions in the plasma hit the cathode, which are accelerated toward exit window by the gradient of an electric potential. The conventional electron beam generators need an electron scanning beam because the small cross section thermal electron emitter is used. The electron beam of large cross-section pulsed electron beam generator do not need to be scanned over target material because the beam cross section is large by 300$cm^2$. We have fabricated the large cross-sectional pulsed electron beam generator with the peak energy of 200keV and beam diameter of 200mm and obtained the large area electron beam in the air. The electron beam current has been investigated as a function of accelerating voltage, glow discharge current, helium pressure, distance from the exit window and radial distribution in front of the exit window.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권4호
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• pp.253-260
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• 1999

In this paper, the impedance characteristic of wire-plate pulsed plasma reactor was investigated by experiment. The experiment have carried out under the several conditions of voltage, wire length and wire-plate distance. The impedance of reactor wad decreased with increasing voltage and wire length. The nature of discharge in reactor was changed from streamer corona to spark with increasing incident energy, from which we understood the critical energy density between the two discharges. Fromthis experiment, we proposed the method for the impedance matching between pulse generator and pulsed plasma reactor. Additionally, we succeeded in the analysis ofstray inductance of 0.5MW reactor using EMTP (ElectroMagnetic Transients Program). This means that EMTP is also useful for the analysis of inevitable stray inductance of forthcoming a large scale reactor.