• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.938-940
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• 1998

In order to improve insulating character and ability of insulating system of power apparatus, the interfacial and complex structure is widely used. However, the interface or complex structure of insulation materials is reported as a weak point which causes breakdown. As the interface of insulation system degrades its electrical property and eventually causes a failure, the datailed phenomenon analysis is reported. The object of this paper is to evaluate dielectric property of PET film with the interface. The $tan{\delta}$ increased with the existence of semiconducting layer and showed prominent decrease as a function of temperature. Also, the $tan{\delta}$ showed prominent increase as a function of frequency. The dielectric properties of interfacial were affected by the interface characteristics.

• Journal of Korean Vacuum Science & Technology
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• v.5 no.2
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• pp.52-55
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• 2001

We report best dielectric function of ZnS by spectroscopic ellipsometry in the 3.7 - 6.0 eV photon energy range at room temperature. Using proper wet chemical etching procedure, natural overlayer was removed to obtain the pure dielectric function of ZnS, which had a higher <$\xi$$_2$> value at the El band gap peak than that previously reported. We also determined the dielectric property of the natural overlayer on ZnS by following the evolution of <$\xi$$_2$> with chemical etching. We found that the optical property of the overlayer was well described by amorphous semiconductor model.

• Journal of the Korean Ceramic Society
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• v.37 no.1
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• pp.12-20
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• 2000

Dielectric property of Ba-modified 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 ceramics having compositions near the morphotropic phase boundary was investigated. For the specimens having Ba contents between 0 and 20 at%, the average transition temperature was decreased linearly with increasing Ba contents and the degree of hysteresis was also decreased with increasing Ba contents. The maximum dielectric constants (K), electric field induced polarization(P) and electrically-induced strain(S) were found to exihibit a maximum value at∼3 at% of Ba. The increase of S and the decrease of hysteresis by minor additions of Ba impurities indicated the development of new higher perfomance actuator materials. The composition of Ba-PMN-PT (10/65/35) may be appropriate for capacitor materials because of low hysteresis and high polarization.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.137-143
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• 2008

High voltage MLCCs with C0G temperature coefficient characteristics could apply DC-DC invertor were investigated for its dielectric properties. Also we manufactured MLCC through various process and studied the characteristics of dielectric break down voltage [BDV] and dielectric property as the variation of thickness in the green sheet and how to pattern the internal electrode. As the thickness of green sheet is increase, the dielectric BDV per unit thickness is decreased. But as the pattern of internal electrodes were floated we could manufacture the high voltage MLCC maintained its dielectric BDV a unit.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1262-1263
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• 2011

Sulfur hexafluoride is the most commly used insulation gas in electrical systems. Gas insulated systems are widely used in the electric power industry for transmission and distribution of electrical energy. When $SF_6$ was first discovered, the potential application was only considered for insulation because of good dielectric properties. But the widespread use of $SF_6$ gas by electric power and other industries has led to increase concentrations of $SF_6$ gas in the atmosphere. This concern as to possible effects on global warming because $SF_6$ is a potent greenhouse gas. That's why firstly we studied uniform and nonuniform field property by mixing $SF_6$ and N2 gas. This paper presents the dielectric strength and insulating property for particle contamination under $SF_6/N_2$ mixtures. Two types of mixed gases(50% $SF_6$_50%$N_2$, 20% $SF_6$_80%$N_2$) were applied. We performed tests for the length and shape of particle. Test gas pressure is from 0.3 to 0.7 Mpa. The study was conducted to develop environment-friendly insulating material for GIS that can reduce $SF_6$ gas and make a design criteria for mixtures.

• Journal of the Korean Vacuum Society
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• v.16 no.6
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• pp.458-462
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• 2007

Spectroscopic ellipsometry is an excellent technique for determining dielectric function. To obtain critical point energy, standard analytic critical point expression is used conventionally for second derivatives of dielectric function which might increase high frequency noise than signal. However, reciprocal-space analysis offers several advantages for determining critical point parameters in optical and other spectra, for example the separation of baseline, information, and high frequency noise in low-, medium-, high-index Fourier coefficient, respectively. We used reciprocal Fourier analysis for removing noise and determining critical point of ZnCdSe alloy.

• Journal of Biosystems Engineering
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• v.32 no.4
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• pp.237-246
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• 2007

In this study, the microwave free-space transmission technique was used to measure the dielectric property of powdered food at microwave frequencies. The sample holder was designed and fabricated to transmit the microwave signals ranging from 1 to 15GHz. From the microwave propagation theory the equation expressing the dielectric property of powdered food was derived and validated by standard dielectrics. The dielectric property of powdered food such as wheat flour, coffee powder and milk powder was measured and analyzed. In the uniform range of bulk density of material, the real parts of permittivity of the food samples increased with the increase of moisture content, bulk density and temperature of the samples. The propagation properties such as attenuation and phase shift increased linearly as the moisture density of the food samples increased. As a measuring frequency of the moisture content, the X-band was recommended.

• Journal of the Korean Ceramic Society
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• v.36 no.9
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• pp.965-973
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• 1999

• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.281-283
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• 2001

The low foamed high strengthen styrofoam samples made by dielectric heating are discussed. We used the oscillator which have the frequency of 13.6MHz and the Power of 7kW. 3 times expanded beads by steaming method were used in our foam-molding test. Internal fusion properties and density of internal structure were improved by dielectric foaming process. At the temperature of 105-110$^{\circ}C$, the internal fusion property was maximally improved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04b
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• pp.153-156
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• 2004

The $Pb(Zr_{0.4}Ti_{0.6})O_3/Pb(Zr_{0.6}Ti_{0.4})O_3$ [PZT(4060)/(6040)] heterolayered thin films were deposited by RF sputtering method on the $Pt/TiO_2/SiO_2/Si$ substrate. The effects of the structural and dielectric properties of PZT heterolayered thin films were investigated. The MFM(Metal Ferroelectric Metal) type capacitors were made using the PZT(6040)/(4060) heterolayered thin films deposited with optimum deposition condition. An enhanced dielectric property was observed in the PZT(4060)/(6040) thin films. Investigating the dielectric constant and dielectric loss characteristics. the application for the next-generation dielectric thin films and memory devices were studied.