• Journal of Electrical Engineering and Technology
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• v.1 no.4
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• pp.534-542
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• 2006

This paper presents results of frequency domain spectroscopy (FDS) measurements on oil-impregnated pressboard insulation, their analyses and use of the data for modeling high frequency response (FRA) of transformers. The dielectric responses were measured in a broad frequency range, i.e. from 0.1 mHz to 1 MHz, on model samples containing different amount of moisture. The responses were parameterized with terms representing dc conductivity, low frequency dispersion and Cole-Cole polarization mechanisms and they were thereafter used to model the FRA response of a three-phase transformer.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.67-69
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• 1998

In order to design or predict the performance of a cylindrical electrostatic motor it is necessary to analyze the torque generated by such a structure. In this paper a simple but sufficiently accurate analytical model is developed for use in design. Conformal mapping are used to model the capacitance and torque of the motor as a function of the rotor position, using a quasi-static, two-dimension approximation, the effect of an insulating dielectric layer on the stator or rotor is also evaluated.

• Bulletin of the Korean Chemical Society
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• v.30 no.4
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• pp.857-862
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• 2009

We model lattice-mismatched group III-V semiconductor $In_{x}Ga_{1-x}$ alloys with the three-parameter anharmonic Kirkwood-Keating potential, which includes realistic distortion effect by introducing anharmonicity. Although the potential parameters were determined based on optical properties of the binary parent alloys InAs and GaAs, simulated dielectric functions, reflectance, and Raman spectra of alloys agree excellently with experimental data for any arbitrary atomic composition. For a wide range of atomic composition, InAs- and GaAs-bond retain their respective properties of binary parent crystals despite lattice and charge mismatch. It implies that use of the anharmonic Kirkwood-Keating potential may provide an optimal model system to investigate diverse and unique optical properties of quantum dot heterostructures by circumventing potential parameter searches for particular local structures.

• Bulletin of the Korean Chemical Society
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• v.14 no.2
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• pp.220-225
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• 1993

The influence of temperature and pressure on the free energy of the ion hydration has been considered. The ion radii measured by conductometric method and the saturated dielectric constant cited from other works were used to calculate the free energy in the hydration shell. The Born equation was modified in order to fit in our model. In our model, the environment of ion consists of three regions. The innermost one is the hydration shell in which water is immobilized and electrostricted, the middle one is the one which contains less ordered waters than the bulk medium, and the outermost one is the bulk water which is under the influence of the electric field of ion. Our results for the free energy of ion hydration were compared with those of other attempts. Especially, ${\Delta}$G$_{hyd}$ of $Li^+$ ion is considerably too negative in this study at given temperature, comparing with those of other attempts. But ${\Delta}$G$_{hyd}$ of other ions coincides with each other.

• Progress in Superconductivity and Cryogenics
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• v.11 no.1
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• pp.45-48
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• 2009

Research on the mechanical properties of the dielectric paper and mini-model cable are important for optimum electrical insulation design of HTS cable, because the HTS cable experience of mechanical stress, such as tensile and bending stress. Also, it is operated at cryogenic temperature. Therefore, this paper discusses the experiment results on the AC and lighting impulse breakdown characteristics, partial discharge inception and extinction characteristics, and external shape change of the insulation layer according to bending strain of the mini-model cable.

• Transactions on Electrical and Electronic Materials
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• v.8 no.3
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• pp.139-142
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• 2007

Organic field-effect transistor (FET) based on a copper Phthalocyanine (CuPc) material as an active layer and a $SiO_2$ as a gate insulator were fabricated and analyzed. We measured the typical FET characteristics of CuPc in air. The electrical characteristics of the CuPc FET device were analyzed by a Maxwell-Wagner model. The Maxwell-Wagner model employed in analyzing double-layer dielectric system was helpful to explain the C-V and I-V characteristics of the FET device. In order to further clarity the channel formation of the CuPc FET, optical second harmonic generation (SHG) measurement was also employed. Interestingly, SHG modulation was not observed for the CuPc FET. This result indicates that the accumulation of charge from bulk CuPc makes a significant contribution.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.5
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• pp.58-65
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• 2009

A forest fire in the area of power line installations may be caused by flashover disturbances in power systems. In this study, experiments were conducted so as to investigate the reduction in dielectric strength caused by combustion flame, and flashover characteristics in the simulated condition of vertical-type model power lines were examined by making shorter and longer the horizontal distance(s) between combustion flame and high-voltage conductors under the application of 60[Hz] a.c. and d.c. high-voltages. As the results of the experimental investigation it is demonstrated that flame can reduce flashover voltages of the model air-gap in shorter range of the horizontal distance(s). Relative air density is considered in order to analyze the reduction causes of the flashover voltages, and it can be seen that the relative air density has a great influence on the flashover characteristics under the presence of combustion flame.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.8
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• pp.41-46
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• 2008

This paper conducts the research on the variation in the characteristics of the resonance and impedance of the metallic parallel plates due to the replacement of the normal dielectric substrate by the metamaterial. The ENG(${\epsilon}<0$), MNG(${\mu}<0}$) and DNG(${\epsilon},{\mu}<0$) types of metamaterial as well as the DPS(Double Positive) material are taken into consideration a full-wave modal analysis method known for accurate computation, as the SRR-kind of Lorentz model for permittivity and metal wire-periodic array-kind of Drude model for permeability, and the behaviors of parallel plates' resonance mode and impedance are observed. Based upon the observation, the design guidelines for the substrate can be addressed regrading how to suppress the parallel plates' spurious resonance modes that degrade the quality of the electronic equipment.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.12
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• pp.601-605
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• 2006

The resistance-capacitance (RC) delay of signals through interconnection materials becomes a big hurdle for high speed operation of semiconductors which contain multi-layer interconnections in smaller scales with higher integration density. Low-k materials are applied to the inter-metal dielectric (IMD) materials in order to overcome the RC delay. Relaxation continuum (RCT) model that includes neutral-species transport model have developed to model the etching process in a capacitively coupled plasma (CCP) device. We present the parametric study of the modeling results of a two-frequency capacitively coupled plasma (2f-CCP) with $N_2/H_2$ gas mixture that is known as promising one for organic low-k materials etching. For the etching of low-k materials by $N_2/H_2$ plasma, N and H atoms have a big influence on the materials. Moreover the distributions of excited neutral species influence the plasma density and profile. We include the neutral transport model as well as plasma one in the calculation. The plasma and neutrals are calculated self-consistently by iterating the simulation of both species till a spatio-temporal steady state profile could be obtained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.1
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• pp.74-79
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• 2002

The EM(Engineering Model) VCO(Voltage Controlled Oscillator) is nonlinear designed for LO(Local Oscillator) of Ka-band satellite transponder. The microstripline coupled with dielectric resonator is implemented as a high impedance inverter to improve the phase noise, and the quality factor of resonant circuit can be transferred to active device with the enhanced loaded quality factor. The developed VCO has the oscillating tuning range of 9.7965~9.8032 GHz for the control voltage range of 0~12 V. This VCO requires the DC power of 8 V and 17 mA. The phase noise characteristics are -96.51 dBc/Hz @10 KHz and -116.5 dBc/Hz @100 KHz, respectively. And, the output power of 7.33 dBm is measured.