• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.243-245
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• 2007

본 연구는 직류 부극성(DC(-)) 전압에서 제조공기(I-Air)의 온도(T)의 변화($+10[^{\circ}C]{\sim}-30[^{\circ}C]$)에 따른 절연특성을 구명하였다. 절연특성은 GIS모의 챔버 주입 압력(P)과 비례하는 특성을 보였으나 T가 저하되면서 그 절연특성이 감소하는 경향을 보이지 않고 오히려 증가하는 구간이 존재하였다. 그리고 챔버내 P의 크기가 클수록 T저하에 대한 P감소율이 더 컸으며, 절연파괴전압($V_B$)감소폭도 이와 비례해서 60[N/$cm^2$]에서 가장 큰 변화를 보였다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1599-1600
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• 2011

현재 사용되는 전력기기와 전기에너지로 구동되는 기기등은 환경 조화와 에너지 절약을 목표로 고전압 대용량화, 축소 소형화 및 고효율화가 진행되는 과정에 있다. 이런 기기들은 전위를 유지하기 위해서 전기절연기술이 필수적이다. 특히 전기절연재료의 역할이 중요해서 재료의 특성이 기기전체의 종합성능을 지배하기도 한다. 본 연구에서는 몰드 변압기의 절연수지로 사용되는 에폭시 복합체와 마이크로 $SiO_2$와 Ag 각 시편의 열팽창률과 유전 특성 및 온도에 따른 절연파괴강도를 측정하여 열적 특성 및 전기적 특성을 검토하고 분석한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.751-755
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• 2007

We have studied the variable conditions of reactive sputtering to prepare AM thin film. The leakage current showed below $10^{-9}A/cm^2$ at the deposition temperature of $250^{\circ}C\;and\;300^{\circ}C$ in the field of 0.1 MV/cm, and it was gradually increased and to be saturated in 0.2 MV/cm. The C-V characteristics of the above mentioned deposition temperature conditions showed a deep depletion phenomenon at inversion region. The C-V characteristics showed similarly under the DC power conditions of 100 and 150 W but were degraded at 200W. When the DC power was 100, 200, and 300 W the dielectric breakdown phenomenon was shown in 2.8, 3.2 and 5.2 MV/cm, respectively. It was found that AIN film was dominated by Poole-Frenkel conduction mechanism.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.189-192
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• 1998

In this paper, we analyzed Microwave-DC conversion efficiency for the rectennas and it's position change. Rectenna consist of a two major parts, receiveing antenna and rectifying circuits. We made two types of 2.45C rectennas which the dipole and the patch antenna. Rectifying circuit is a GaAs-schottky diode with a large forward current and reverse breakdown voltage. The results of RF-DC conversion efficiency for two rectennas, patch type has 75.6% efficiency with 400$\Omega$ load resistor and dipole type has 69.75% efficiency with 360$\Omega$ load resistor. When the rectennas has optimal load resistor, Rectenna efficiency shows of $\pm10%$ at $70^{\circ}$~$110^{\circ}$ position.

• Transactions on Electrical and Electronic Materials
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• v.11 no.5
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• pp.216-221
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• 2010

The microstructure, electrical properties, and DC-accelerated aging behavior of the Zn-Pr-Co-Cr-Y-Er (ZPCC-YE) varistors were investigated for different amounts of erbium oxide ($Er_2O_3$). The microstructure consisted of zinc oxide grain and an intergranular layer ($Pr_6O_{11}$, $Y_2O_3$, and $Er_2O_3$-rich phase) as a secondary phase. The increase of $Er_2O_3$ amount decreased the average grain size and increased the sintered density. As the $Er_2O_3$ amount increased, the breakdown field increased from 5094 V/cm to 6966 V/cm and the nonlinear coefficient increased from 27.8 to 45.1. The ZPCC-YE varistors added with 0.5 to 1.0 mol% $Er_2O_3$ are appropriate for high voltage, with high nonlinearity and stability against DC-accelerated aging stress.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.8
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• pp.78-88
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• 1992

To improve the characteristics of sub$\mu$m short channel MOSFET device, a new device having the convex structure is proposed. This device has 3-dimensionally expandable channel length according to the vertical etched silicon height. For the purpose of comparing the DC and AC characteristics, planar device is also fabricated. Comparing the channel length, the convex device with 0.4$\mu$m silicon height is larger about 0.56$\mu$m in NMOS and 0.78$\mu$m in PMOS than planar devices. DC characteristics, such as threshold voltage, operational current, substrate current and breakdown voltage are compared together with AC characteristics using the ring oscillator inverter delay. Also process and device simulation are performed and the differences between convex and pranaldevice are also compared.

• ETRI Journal
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• v.24 no.5
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• pp.333-340
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• 2002

We propose a new process technique for fabricating very high-density trench MOSFETs using 3 mask layers with oxide spacers and a self-aligned technique. This technique reduces the device size in trench width, source, and p-body region with a resulting increase in cell density and current driving capability as well as cost-effective production capability. We were able to obtain a higher breakdown voltage with uniform oxide grown along the trench surface. The channel density of the trench DMOSFET with a cell pitch of 2.3-2.4 ${\mu}m$ was 100 Mcell/$in^2$ and a specific on-resistance of 0.41 $m{\Omega}{\cdot}cm^2$ was obtained under a blocking voltage of 43 V.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.10
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• pp.867-873
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• 2002

We have designed and fabricated the slidacs type automatic voltage regulator(SVR) that is able to control the output voltage continuously according to load variation. Especially, the frictions between the surface of contact of the slidacs coils and the output wire moving shaft arc reduced by modifying the mechanical configuration of surface of contact of slidacs from the conventional sliding one into the proposed rotary one composed of cylindrical bearing. Thus, SVR using cylindrical bearing proposed in this study has less noise than the conventional one owing to the reduction of friction, and its breakdown ratio caused by the abrasion of contact materials is reduced as well. We have designed U motor driving circuit for controlling the output wire moving shaft, and introduced the digital control method using the pulse width modulation(PWM) output for controlling DC motor.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.49-52
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• 2008

현재 산업사회의 발달과 더불어 신뢰성 높은 양질의 전기에너지와 운전 및 보수의 간편화, 계통운용의 신뢰성의 확보가 요구되고 있다. 또한 $SF_6$을 대체할 친환경적인 절연매체의 개발이 절실히 요구되고 있다. 이에 본 연구는 모의 GIS내 친환경적인 절연재료인 질소($N_2$)와 산소($O_2$)의 혼합가스($N_2:O_2=79:21$, $N_2:O_2=60:40$, $N_2:O_2=40:60$)의 기본적인 절연특성을 구명함으로서 각종 전력응용 설비의 절연매체로 사용가능함을 구명하고저 한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.11
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• pp.1639-1644
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• 2015

Auxiliary air compressor(ACM) applied to railroad cars is a device which controls amount of compressed air in order that pantographs can be mounted correctly on the roof of an electric train. Existing ACMs consist of dc motors and brushes wear out due to friction with a commutator. Therefore, continuous maintenance is required. However, three phase BLDC motors have higher power density compared to dc motors and the machine maintenance is not needed because electric commutation is possible. The three phase generally uses hall sensors to get position information and this enables the accurate control. This paper suggests an algorithm that compensates the errors occurred when the hall sensors have a breakdown for stable operation.