• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.6
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• pp.1460-1464
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• 2010

In the paper, the breakdown voltage of Trench D-MOSFET have been analyzed by using MircoTec. The technology for characteristic analysis of device for high integration is changing rapidly. Therefore to understand characteristics of high-integrated device by computer simulation and fabricate the device having such characteristics became one of very important subjects. A Trench MOSFET is the most preferred power device for high voltage power applications. The oxide thickness and doping concentration in Trench MOSFET determines breakdown voltage and extensively influences on high voltage. We have investigated the breakdown voltage characteristics according to variation of doping concentration from $10^{15}cm^{-3}$ to $10^{17}cm^{-3}$ in this study. We have also investigated the breakdown voltage characteristics according to variation of oxide thickness and junction depth.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.10
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• pp.82-88
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• 2014

This paper presents the results of model tests for the attachment process of lightning leader to ground which is one of poorly understood processes of cloud-to-ground lightning discharges. In order to simulate the attachment process of lightning leader to ground, we investigated the discharge characteristics of air gap between the tip of needle-shaped electrode and the soil surface as a parameter of moisture content in soils when the positive and negative $1.2/50{\mu}s$ lightning impulse voltages are applied. The breakdown voltage and the discharge light were observed. As a result, the attachment processes of lightning leader to ground are strongly dependent on the grain size and the moisture content of soils. The time to breakdown was shortened with increasing the magnitude of incident impulse voltages. The delay time from application of the highest voltage to breakdown in sand is shortened with increasing the moisture content. The delay time from application of the voltage to breakdown in gravel varied from about $0.5{\mu}s$ to several ${\mu}s$. As the moisture content in soil increases, the breakdown voltages are decreased and the breakdown voltage versus time to breakdown curves are shifted toward the lower side. The results obtained in this work are similar to those for non-uniform air gap stressed by lightning impulse voltages.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.5
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• pp.1196-1202
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• 2013

This paper have analyzed the change of breakdown voltage for channel doping concentration and device parameters of double gate(DG) MOSFET using two dimensional potential model. The low breakdown voltage becomes the obstacle of power device operation, and breakdown voltage decreases seriously by the short channel effects derived from scaled down device in the case of DGMOSFET. The two dimensional analytical potential distribution derived from Poisson's equation have been used to analyze the breakdown voltage for device parameters such as channel length, channel thickness, gate oxide thickness and channel doping concentration. Resultly, we could observe the breakdown voltage has greatly influenced on device dimensional parameters as well as channel doping concentration, especially the shape of Gaussian function used as channel doping concentration.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.9
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• pp.911-915
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• 2004

In this study, the electrical characteristics of high-voltage LDMOSFET fabricated by the existing CMOS technology were investigated depending on its process and design parameter. In order to verify the experimental data, two-dimensional device simulation was carried out simultaneously. The off- state breakdown voltages of n-channel LDMOSFETs were increased nearly in proportional to the drift region length. For the case of decreasing n-well ion implant doses from $1.0\times{10}^{13}/cm^2$ to $1.0\times{10}^{12}/cm^2$, the off-state breakdown voltage was increased approximately two times. The on-resistance was also increased about 76 %. From 2-D simulation, the increase in the breakdown voltage was attributed to a reduction in the maximum electric field of LDMOS imolanted with low dose as well as to a shift toward n+ drain region. Moreover, the on- and off-state breakdown voltages were also linearly increased with increasing the channel to n-tub spacing due to the reduction of impact ionization at the drift region. The experimental and design data of these high-voltage LDMOS devices can widely applied to design smart power ICs with low-voltage CMOS control and high-voltage driving circuits on the same chip.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.205-210
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• 2010

In this study, a brass electrode gas discharge tube (GDT) was prepared to investigate its discharge characterization, which affects surge protection efficiency and lifetime of GDT. Discharge characterization of GDT using a brass electrode was investigated by changing applied voltage gradient and nitrogen gas pressure inside the GDT. As applied voltage gradient in GDT increased, electrical breakdown voltage and threshold energy largely increased and electrical breakdown time delay decreased. It was found that electrical breakdown voltage, electrical breakdown time delay, and threshold energy were largely decreased with decreasing the nitrogen gas pressure in GDT. As a result, electrical breakdown voltage, electrical breakdown time delay, threshold energy needed to be decreased to increase surge protection efficiency and lifetime. It was also found that the nitrogen gas pressure of GDT influenced strongly the performances as well as life span of it.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.4
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• pp.103-109
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• 2010

In this paper, breakdown characteristics of soil in a coaxial cylindrical electrode system stressed by impulse currents were experimentally investigated. The breakdown voltage and current waveforms for 4 types of soils were measured, and the threshold electric field intensity, the time-lag to breakdown and the voltage-current (V-I) curves were analyzed and discussed. As a result, the breakdown voltage and current waveforms are strongly dependent on the grain size of soil, and the voltage and current waveforms for gravel and sand differ from those for silt and loess. The threshold electric field intensity Ec is increased in the order of gravel, sand, loess and silt. The V-I curves for all test samples show a 'cross-closed loop' of ${\infty}$-shape. Also, the time-lag to breakdown for gravel and sand are longer than those for silt and loess. It is expected that the results presented in this paper will provide useful information on the design of improving transient performance of a grounding electrode system subjected to lightning current considering the soil ionization.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1538-1539
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• 2011

In this study, we have investigated the dielectric breakdown by measuring AC (60Hz) breakdown strength of the fluids in accordance with IEC 156 standard and have compared the results with references. It was found that the dielectric breakdown voltage of pure transformer oil is around 12 [kV] with the gap distance of 1.5mm between electrodes. In case of our transformer oil based magnetic fluids with 0.1% < ${\Phi}$(volume concentration of magnetic particles) <0.6%, the dielectric breakdown voltage shows above 30 [kV], which is 2.5 times higher than that of pure transformer oil. It can be explained by the changed ionization process by adding nanoparticles in pure transformer oil, which is due to trapped fast electrons and slow negative nanoparticles. Moreover, in case of the fluid with applied magnetic field, the dielectric breakdown voltage increases above 40 [kV], which is 3.3 times higher than that of pure transformer oil.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.9
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• pp.533-540
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• 2000

Lightning impulse $(1.2/44[\mus])$ and damped oscillating impulse $(Osc./44[\mus])$ : 0.83[MHz]) breakdown characteristics in sulphur-hexafluoride/nitrogen (SF6-N2) mixtures were investigated. The predischarge currents were observed to clarify the breakdown mechanism. th experiments were carried out under nonuniform electric fields disturbed by a needle-shaped protrusion whose length and diameter are 10[mm] and 1[mm] at total gas pressure up to 0.5[MPa] with nitrogen concentrations varying from 5 to 20[%] in the mixture. The electrical breakdowns of SF6-N2 mixtures for both the positive and negative polarities develop with steplike pulses in leader mechanism and the breakdown voltage -time (V-t) characteristics were affected by the space charge. The voltage-time curves for the negative oscillating impulse voltage were extended over the longer time range. The minimum breakdown voltages for the negative lightning and oscillating impulse voltage were higher than those for the positive ones. in particular the positive breakdown voltages were independent of the gas pressure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.254-257
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• 1997

In this paper, we investigated the effects of gap length and tip radius influenced in breakdown of mineral based insulation oil Electrode system was needle-plane geometry It is to model conductive extrusions in oil filled electrical power apparatus. The tip radius of needle electrode was 5, 10, 20 and 25${\mu}{\textrm}{m}$, respectively. We measured breakdown voltage for each of tip radius with increasing electrode gap, 2mm to 12mm. It was calculated electrical breakdown strength at tip using Mason\`s equation from breakdown voltage As gap lenght increased. breakdown strength increased linearly. But, as tip radius of needle increased, breakdown strength decreased exponentially. It can be explained by tole phenomenon that electron is easily injected, as tip radius increases, and effective work function decreases. When appling DC voltage. breakdown 7tr7ilgtll was higher wheal polarity of needle was negative than positive. It is because of the space charge effect ill accordance with the influence of liquid motion.

• Journal of the Korean Society of Safety
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• v.19 no.1
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• pp.56-59
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• 2004

In this paper, we investigated the influence of gap length and tip radius on breakdown of mineral based insulation oil. Applied voltages were DC and AC voltage. Electrode system was needle-plane structure. The tip radius of needle electrode was 5, 10, 20 and 25${\mu}m$, respectively. We measured breakdown voltage for each of tip radius with increasing electrode gap, 2mm to 12mm. Electric breakdown strength at tip was calculated using Mason's equation contained geometric figure. As gap length increased, breakdown strength increased linearly. But, as tip radius of needle increased, breakdown strength decreased exponentially. It can be explained by the phenomenon that electron is easily injected, as tip radius increases, and effective work function decreases. When appling DC voltage, breakdown strength was higher when polarity of needle was negative than positive. It is because of the space charge effect in accordance with the influence of liquid motion.