• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.119-124
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• 1998

This paper proposes a new repulsive-Maglev vehicle in which a vertical type PM linear synchronous motor (LSM) can levitate and propel simultaneously, independently of the vehicle speeds. A compact control method is developed which is based on the concept of controlling individually the levitation system by armature-current and the propulsion system by mechanical load-angle. The levitation-motion control experiments have carried out successfully together with positioning at standstill. The pitching motion has been compensated for very well by using the zero-phase-current control method proposed here.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.6
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• pp.458-462
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• 2011

Soution-processed ZrInZnO (ZIZO) thin-film transistors (TFTs) with varying Zr content were fabricated. The ZIZO TFT (Zr=20 at. %/Zn) has an optimal performance with the saturation field effect mobility of 0.77 $cm^2/Vs$, the threshold voltage (Vth) of 2.1 V, the on/off ratio of $4.95{\times}10^6$, and subthreshold swing (S.S) of 0.73 V/decade. Using this optimized ZIZO TFT, the positive and negative gate bias stress according to annealing temperature was also investigated. While the Vth shifts dramatically after 1,000 s of both gate bias stresses, variations in the S.S are negligible. It suggests that electrons or holes are tem porarily trapped in the gate insulator, the semiconductor, or the interface between both layers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.103-104
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• 2008

In this paper we report upon an investigation into the effect of DC bias voltage on the electrical and optical properties of Gallium doped zinc oxide (GZO) film. GZO films were deposited on glass substrate without substrate temperature by RF magnetron sputtering from a ZnO target mixed with 5 wt% $Ga_2O_3$. we investigated sample properties of bias voltage change in 0 to -60 V. We were able to achieve as low as $5.89\times10^{-4}$ ${\Omega}cm$ and transmittance over 87%. without substrate temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.416-420
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• 2004

Varistors based on M.Matsuoka were prepared from ZnO nanopowders, every one of which had bar type and about less 100nm length. The compact green disks were conventionally sintered in air for 2 hours at a temperature of $1050^{\circ}C$. The Varistors with nonlinear coefficient ${\alpha}=45$, leakage current $I_{\ell}=2{\times}10^{-7}A/cm^2$, operating voltage 9000v/cm, and average grain size $3{\mu}m$ were obtained. The advantages of the samples were due to greater structural homogenity, higher density, smaller grain size.

• Transactions on Electrical and Electronic Materials
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• v.16 no.2
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• pp.82-85
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• 2015

Mechanical and electrical properties of epoxy/silica microcomposites were investigated. The cycloaliphatic- type epoxy resin was diglycidyl 1,2-cyclohexanedicarboxylate and the curing agent was of an anhydride type. To measure the glass transition temperature (Tg), dynamic differential scanning calorimetry (DSC) analysis was carried out, and tensile and flexural tests were performed using a universal testing machine (UTM). Electrical breakdown strength, the most important property for electrical insulation materials, and insulation breakdown strength were also tested. The microcomposite with 60 wt% microsilica showed maximum values in mechanical and electrical properties.

• Transactions on Electrical and Electronic Materials
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• v.12 no.4
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• pp.156-159
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• 2011

SiNx:H films have been widely used for anti-reflection coatings and passivation for crystalline silicon solar cells. In this study, SiNx:H films were deposited using high frequency (13.56 MHz) direct plasma enhanced chemical vapor deposition, and the optical and passivation properties were investigated. The radio frequency power, the spacing between the showerhead and wafer, the $NH_3/SiH_4$ ratio, the total gas flow, and the $N_2$ gas flow were changed over certain ranges for the film deposition. The thickness uniformity, the refractive index, and the minority carrier lifetime were then measured in order to study the properties of the film. The optimal deposition conditions for application to crystalline Si solar cells are determined from the results of this study.

• ETRI Journal
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• v.42 no.4
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• pp.465-467
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• 2020

• Transactions on Electrical and Electronic Materials
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• v.3 no.1
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• pp.23-29
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• 2002

The electronic properties of Carbon Nanotube(CNT) are currently the focus of considerable interest. In this paper, the electronic properties of finite length effect in CNT for the carbon nano-scale device is presented. To Calculate the electronic properties of CNT, Empirical potential method (the extended Brenner potential for C-Si-H) for carbon and Tight Binding molecular dynamic (TBMD) simulation are used. As a result of study, we have known that the value of the band gap decreases with increasing the length of the tube. The energy band gap of (6,6) armchair CNT have the ranges between 0.3 eV and 2.5 eV. Also, our results are in agreements with the result of the other computational techniques.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.2
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• pp.215-220
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• 2016

Monolithically integrated devices are strongly desired in next generation power ICs to reduce the chip size and improve the efficiency and frequency response. Three examples of the embedment of different functional diode(s) into AlGaN/GaN heterojunction field-effect transistors are presented, which can minimize the parasitic effects caused by interconnection between devices.

• KIEE International Transactions on Power Engineering
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• v.5A no.4
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• pp.350-356
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• 2005

Earth equipments are essential to protect humans and other types of equipment from abnormal conditions. Earth resistance and potential must be restricted within a low value. An estimation algorithm of earth parameters and equivalent resistivity is introduced to calculate reliable earth resistance in this research. The proposed algorithm is based on the relationship between apparent resistances and earth parameters. The proposed algorithm, which approximates the non-linear characteristics of earth by using the Artificial Neural Network (ANN), estimates the earth parameters and equivalent resistivity. The effectiveness of the proposed method is verified with case studies.