• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.7
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• pp.1366-1371
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• 2011

The resonant converter cause the high voltage stress according to the input voltage, which increases the conduction loss in converter power switches. The topology of LLC half bridge resonant converter provides ZVS characteristic and also the stress of voltage and current is smaller than that of the general resonant converters. So we can expect the higher efficiency. In this paper, the analysis of the characteristics of the converter efficiency and the best conditions for highest efficiency were investigated. As a result, the efficiency of utilizing up to 93% is achieved.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1568-1570
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• 2003

We have studied the I-V characteristics of polytetrafluoroethylene(PTFE) thin film depending on a variation of thickness. Polymer PTFE buffer layer was made using thermal evaporation technique. The device was made in the structure of ITO/PTFE/Al. We have observed the NDR(negative differential resistance) behavior between 2.5V and 5V. There are some reports on this NDR behavior in the polymer thin film[1]. We have studied the NDR behavior depending on a variation thickness. As the film thickness increased, The NDR behavior decreased and moved in low electrical field, and we have studied the conduction mechanism of PTFE thin film.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.73-74
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• 2007

We fabricated strained-SOI(sSOI) n-/p-MOSFETs and investigated the electron/hole mobility characteristics. The subthreshold characteristics of sSOI MOSFETs were similar to those of conventional SOI MOSFET. However, The electron mobility of sSOI nMOSFETs was larger than that of the conventional SOI nMOSFETs. These mobility enhancement effects are attributed to the subband modulation of silicon conduction band.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.95-97
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• 2003

This paper describes electrical properties such as electrical conduction characteristics and space charge distributions of polyaniline/polystyrene conducting blends. It is interesting to note that the charging current decreased as the temperature was elevated when DC voltage was applied, and also the hopping distance decreased with the increase of temperature for the PANI/HIPS blends, while generally, the hopping distance decreases as the charging current increases. It is exposed that this result is opposed to widely known phenomenon. It could be examined viewing space charge distributions by a pulsed electroacoustic (PEA) method.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.988-991
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• 1992

A new zero voltage switching PWN converter family is presented by using a new ZVS PWN module (ZPM) with a saturable inductor which prevents diode junction capacitors and a commutation inductor from resonating. The new converters show almost all characteristics of the conventional PWN converters. A boost ZVS PWN converter is applied to a power factor correction circuit. It operates on an continuous conduction mode. Experimental results for output power of 1kW are presented.

• Electrical & Electronic Materials
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• v.10 no.8
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• pp.756-762
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• 1997

In this paper the change of electrical properties of transformer oil due to electron beam irradiation is investigated. The specimens are produced with a some different dose of 0.5[Mrad], 1[Mrad] and 2[Mard] except for original specimen. The physical properties of each specimen is analyzed by using the FT-IR spectrum. So it is confirmed that carbonyl groups are increased according to the increase of electron beam dose and also that the nitric compounds are disappeared. The magnitude of dielectric dissipation factor appears maximum value by the contribution of dipoles and ions in the low temperature low voltage region and it is stable due to the saturation of carriers in the high temperature high voltage region in the electric conduction characteristics. Volume resistivity is also measured one of original specimen is larger than irradiated specimen.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.880-882
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• 1997

The secondary arcing phenomenon can be hardly modeled for computer simulation due to its particularly-nonlinear characteristics. This paper describes a new computer modeling technique for the secondary arc which can be implemented with the EMTP MODELS. The computer model proposed is based on realistic arc conduction behaviors through newly designed variable resistor modules which can be supported in the EMTP. In this Paper, for the variable resister modules, a new variable arc resistance formula is proposed. Simulation results using the proposed technique are compared with some previous studies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.77-81
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• 1992

$C_{22}$-Quinolium-TCNQ LB films were deposited on the glass substrates by Langmuir-Blodgett technique at room temperature. Transfer ratios and UV-visible absorption spectra were studied for X, Y and Z-Types. Absorption in Z-Type was higher than X and Y-Types, which indicates a better arrangement in this type. We have also investigated dc electrical conductivities and ac responses along the horizontal and vertical direction to the film surface. As a result, we are able to determine the capacitance of film and the measured horizontal conductivity was about $10^{-7}$~$10^{-8}$ S/cm.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.157-159
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• 1996

The secondary arcing phenomenon can be hardly modeled for computer simulation due to its particularly nonlinear characteristics. This paper describes a new computer modeling technique for the secondary arc which can be implemented with the EMTDC. The computer model proposed is based on realistic are conduction behaviors through both FIT and variable resistor modules which is supported in the EMTDC. Simulation results using the proposed technique are compared with some previous studies.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2166-2168
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• 2005

This paper presents the frequency - dependent characteristics of leakage currents flowing through ZnO varistor. The leakage current - voltage (V-I) characteristic curves of the commercial ZnO varistor were measured. The resistive leakage current was increased with increasing the magnitude and frequency of the applied voltage in the low conduction region. The power losses of ZnO varistor increase as the frequency of applied voltage increases, because of the dielectric loss related to the frequency of the test voltage.