• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.12
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• pp.592-600
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• 2001

This Paper presents the transient analysis of the single-phase line-start permanent magnet synchronous motor. To analyse the starting characteristics, the dynamic equation which is combined electric dynamic equations with mechanical dynamic equation is used. The electric dynamics are derived from the d-q axis voltages of stator and rotor respectively. Especially, symmetrical components transformation is used to consider unbalanced magnetic field which is produced by single-phase input. Non-linear d-q axis inductances according to current amplitude and current phase angle are calculated by Finite Element Method and applied to lumped parameter circuit. The analysis methods are validated by comparing simulated and experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.7
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• pp.72-78
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• 2008

The line-of-sight(LOS) stabilization system is a precision electro-mechanical gimbals assembly for suppressing vibration due to its environment and tracking the target in a desired direction. This paper describes the design of gimbals system to reject the disturbance and to improve stabilization. The controller consists of a DSP with transducer and actuator interfaces. Unknown parameters of the gimbals are estimated by the signal compression method. The cross-correlation coefficient between the impulse response from the assumed model and the one from model of the gimbals is used to obtain the better estimation. The quasi-impulse response through linear element included in the gimbals could be obtained by the signal compression method. The unknown parameter of the linear element could be estimated as comparing the bode plots for impulse response from gimbals with them from model's response.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2216-2218
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• 2000

This paper deals with finite element eigenvalue problem using electric field intensity to extract the even and odd impedance for a coupled-line waveguide structure. Calculations for the even-and-odd impedance of a coupled line waveguide structure are achieved based on the relative impedance concept for a waveguide with electric and magnetic wall containes.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.1995-1999
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• 2009

A partial discharge(PD) measurement is a very effective method to assess the insulation condition of high-voltage machines. It is necessary that the life time of the on-line PD measurement sensor is assessed. Therefore, the electrical life time assessment method of ceramic element was reviewed in order to estimate the life time of the on-line PD measurement sensor. The samples were prepared according to the reviewed method and were tested at 8kV, 9kV and 10kV. Based on the obtained results, the life time constant is shown above 59. Also, it is assumed that the estimated life time constant can be used to anticipate the life time and to assess the conformity of the on-line PD measurement sensor.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.6
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• pp.3773-3778
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• 2013

Increased oxidative stress and changes in DNA methylation are frequently detected in bladder cancer patients. We previously demonstrated a relationship between increased oxidative stress and hypomethylation of the transposable long-interspersed nuclear element-1 (LINE-1). Promoter hypermethylation of a tumor suppressor gene, runt-related transcription factor 3 (RUNX3), may also be associated with bladder cancer genesis. In this study, we investigated changes of DNA methylation in LINE-1 and RUNX3 promoter in a bladder cancer cell (UM-UC-3) under oxidative stress conditions, stimulated by challenge with $H_2O_2$ for 72 h. Cells were pretreated with an antioxidant, tocopheryl acetate for 1 h to attenuate oxidative stress. Methylation levels of LINE-1 and RUNX3 promoter were measured by combined bisulfite restriction analysis PCR and methylation-specific PCR, respectively. Levels of LINE-1 methylation were significantly decreased in $H_2O_2$-treated cells, and reestablished after pretreated with tocopheryl acetate. Methylation of RUNX3 promoter was significantly increased in cells exposed to $H_2O_2$. In tocopheryl acetate pretreated cells, it was markedly decreased. In conclusion, hypomethylation of LINE-1 and hypermethylation of RUNX3 promoter in bladder cancer cell line was experimentally induced by reactive oxygen species (ROS). The present findings support the hypothesis that oxidative stress promotes urothelial cell carcinogenesis through modulation of DNA methylation. Our data also imply that mechanistic pathways of ROS-induced alteration of DNA methylation in a repetitive DNA element and a gene promoter might differ.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.1
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• pp.85-92
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• 2002

In this study, we analyzed and experimented micro-strip line inductors and capacitors for a SAW duplexer, an important devise for mobile communication. For SAW duplexers, micro-strip line lumped elements must have small impedance values, below several tens of nH or several tens of pF, and a small area pattern. In this study, we performed theoretical analysis of flat line type, meander line type, and spiral line type inductors and interdigital capacitors on a LiTaO$_3$ Piezo-crystal. We proposed a measurement method to evaluate small values of lumped elements accurately with network analyzer. In experiments, we confirmed validity of the theoretical analysis method through fabrication and characterization of micro-strip line lumped elements. The analysis method in this paper can be applied to SAW duplexers well as other microwave devices.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.10
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• pp.1286-1293
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• 1995

Modified equivalent lumped element model for square spiral inductors have been derived. This model shows more accurate analysis performance than conventional models, and gives reliable design parameters. And this model is made through comparison among distributed multiple coupled line, numerical analysis and experimental data.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.803-812
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• 2023

The subsea separator of an offshore plant for offshore oil and gas development performs the process of separating oil and gas from crude oil produced in the subsea. The oil-gas subsea separator can be divided into a gravity type that separates fluids by gravity and an in-line type that separates fluids using centrifugal force of density. In the case of the deep sea, the development of a small in-line type separator is required due to manufacturing cost and safety problems caused by water pressure. Therefore, in this study, the gas-liquid phase separation efficiency of the subsea separator was identified through the study of the multiphase flow characteristics of the in-line type separator. For the optimal design of the in-line type separator, the shape of the internal swirl element(ISE) was selected first, and the separation efficiency results for each section of the in-line type separator were analyzed. This study was conducted in parallel with experiments and numerical analysis, and it is expected that the reliability and efficiency of the in-line type separator will be improved through the results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.77-77
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• 2010

We used eddy current sensor for diagnosis of power line. The power line according to the cross section has 6~18 element wires. The corrosion of power line was made by sodium hydroxide. The corrosion time of power line was from 18 hours to 27 hours. We obtained physical characteristics from tensile and torsion tests of power line. The eddy current Characteristics of power line according to the corrosion appeared change of amplitude 200 ~ 800 mV.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.754-755
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• 2008

This paper presents a method for reducing the Total Harmonic Distortion(THD) of line-line back_EMF of the IPMSM with distributed winding under the no-load condition. Firstly, the specific harmonic components of line-line back EMF are reduced considering with winding factor. Secondly, THD of line-line back EMF is minimized according to change of pole angle using by Space harmonic Analysis. Finally, the optimal design for minimizing the THD is conducted using response surface methodology with finite element analysis. The validity of the design method dealt with in this paper is demonstrated by comparison between the THD of optimal model and initial model.