• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.5
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• pp.217-220
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• 2005

We have fabricated a superconducting YBCO system according to the pyrolysis method and low pressure apparatus. In our experiment, the X-ray diffraction pattern of the non doped YBaCuO layer indicated that the superconductor contained only 90K phase crystal. The critical temperature and critical current density for a thick layer at $650^{\circ}C$ were Tc=90 K and $Jc=6{\times}10^{4}A/cm^2$ at 90K. In low pressure apparatus, the 90 K phase YBaCuO was grown at a lower temperature compared with the normal system. Tc and Jc at $650^{\circ}C$ were Tc = 90 K and $Jc=6{\times}10^{4}A/cm^2$ at 90K.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.97-103
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• 2004

In general the starting current of single phase induction motor is 3 to 6times of the rated current It make flickering an electric lamp, dispersion a TV screen, insulation destructing an electric motor and momentary blazing of house wiring. Thus it happens losing an electric power loss and reducing an efficiency and a life of home electrical apparatus. In this paper, we proposed the method of reducing staring current with 3.7(%) using TRIAC and ACCT(alternated current transformer) in order to improve the above problem And also we verified semipermanent system with using semiconductor element.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.297-300
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• 1997

In this study, The PVDF thin film was fabricated on the one method of dry-process the physical vapor deposition method, applied electric field, and evaporation control in $\beta$-PVDF thin film preparation. A study on the electric-field-phase change of PVDF thin film in physical vapor deposition using the polymer deposition apparatus which are manufactured for oneself. In the analysis of Fourier-Transform Infrared spectra, according to increasing of electric field intensity, the 510$cm^{-1}$ / peak and 1273$cm^{-1}$ / peak which are showed in $\beta$-PVDF increase, on the contrary the 530$cm^{-1}$ / peak and 977$cm^{-1}$ / peak which are showed in $\alpha$-PVDF decrease.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.4
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• pp.198-202
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• 2005

The simulation of hydraulic pressure distribution of discharge tube with globular beads and the removal characteristics of Escherichia coli by the discharge tube with globular beads were estimated. The removal characteristic of Escherichia coli was related to the input voltage because the electric field is increased according to input voltage. As the passing amount of test water in discharge tube is increased, the removal ratio of Escherichia coli was increased because passing numbers of electric field section is increased.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1757-1759
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• 2000

To make a inspection and maintenance of the high voltage equipment, electric machinery to transmit and distribute the electric power, the appearance of a simple and inexpensive indicator with which the charge condition of bare conductor parts could be read at a Stance has been needed. Liquid crystal has recently been expanding its application rapidly in appliances for everyday use. Since its display energy is extremely small, it is possible to obtain the working current with simple condenser voltage divider that makes use of stray capacity when it is applied to electric power equipment. Thus, an apparatus has finally appeared which is close to the one they have sought and indicates the existence of voltage impressions.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.935-940
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• 2006

Present periodic maintenance activities are carried on electric rolling stock in Korea based on predetermined inspection intervals. And this can be seen as a first generation of maintenance techniques without taking into consideration a degree of aging or degradation of the componets. In this study, we have analyzed the current status of maintenance being used in the techniques in various activities such as overseas railway operation organization, and good cases for the advanced country's maintenance system being carried out effectively. Based on the analysis, we would derive implications for efficient application and improvement guidance of maintenance system in electric rolling stock.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.15-16
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• 2015

According to 2014 fire statistical yearbook in the National Fire Data System, a main cause of fire is electrical fire except carelessness fire. Joint/contact badness is the one of the main cause of electrical fire. Furthermore, power relays which are used in electric panel board, motor control center and automation controller, are main element of automation system in the industry field. Overload, voltage unbalance and open-phase due to joint/contact badness of terminal make electric accidents or electrical fires. In order to prevent joint/contact badness of terminal, this paper proposes a sensing circuit of chattering, tracking, arc current, voltage unbalance and open-phase etc. Some experimental tests of the proposed apparatus confirm practicality and validity of the theoretical results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.6
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• pp.390-395
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• 2015

Molded insulation materials are widely used from large electric power transformer apparatus to small electrical machinery and apparatus. In this study, by adding MgO with the average particle of several tens nm and the excellent thermal conductivity into molding material, we improved the problem of insulation breakdown strength decrease according to rising temperature in overload or in bad environmental condition. We confirmed the life evaluation by using the insulation breakdown and inverse involution to investigate the electrical characteristics of nano-composites materials. By using a scanning electron microscope, it is confirmed that MgO power with the average particle size of several tens nm is distributed and the filler particles is uniformly distributed in the cross section of specimens. And it is confirmed that the insulation breakdown strength of Virgin specimens is rapidly decreased at the high temperature area. But it is confirmed that the insulation breakdown strength of specimens added MgO slow decreased by thermal properties in the high temperature area improved by the contribution of the heat radiation of MgO and the suppression of tree. The results of life prediction using inverse involution, it is confirmed that the life of nano-composites is improved by contribution of MgO according to the predicted insulation breakdown strength after 10 years of specimens added 5.0 wt% of MgO is increased about 2.9 times at RT, and 4.9 times at $100^{\circ}C$ than Virgin specimen, respectively.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.935-943
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• 2015

Permanent magnetic actuators (P.M.A.s) are widely used to drive medium-voltage-class vacuum circuit breakers (V.C.B.s). In this paper, a method for design optimization of a P.M.A. for V.C.B.s is discussed. An optimal design process employing the response surface method (R.S.M.) is proposed. In order to calculate electromagnetic and mechanical dynamic characteristics, an initial P.M.A. model is subjected to numerical analysis using finite element analysis (F.E.A.), which is validated by comparing the calculated dynamic characteristics of the initial P.M.A. model with no-load test results. Using tables of mixed orthogonal arrays and the R.S.M., the initial P.M.A. model is optimized to minimize the weight of the permanent magnet (P.M.) and to improve the dynamic characteristics. Finally, the dynamic characteristics of the optimally designed P.M.A. are compared to those of the initially designed P.M.A.

• Journal of the Korean Society of Safety
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• v.5 no.3
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• pp.56-62
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• 1990

This study is conducted to analyze exact causes of occupational fatalities and results are as follows ： 1) The number of fatalities in establislment which employed less than 50 workers is 605(40.1％ ). Age of sixties and seventies is occupied by 10 percent with there being old-aged trend. Fatal workers who were employed less than 3 months are 39.5 percent and fatal workers who were employed more than 10 years are 11.9 percent. Safety training is necessary for newly recruited and long employed workers. 2) Accident type is, in sequence, fall from elevation, traffic accident, disease, contact with electric current, and hazardous condition is, in order, inadequate guard, hazardous method or procedure, public hazard, and agency of accident is, in sequence, temporary structure/building/structure, powered transport vehicle, passenger vehicle, hoisting or lifting apparatus, and unsafe act is, in order, driving error, failure to secure or warn. 3) The results of cross-tabulation for hazardous condition and accident type is, in sequence, traffic accident by public hazard, fall from elevation by hazardous method or procedure, fall from elevation as well as contact with elctric current by inadequate guard. The result of cross-tabulation for agency of accident and accident type is, in order, fall from elevation by temporary structure/building/structure, traffic accident of passenger vehicle and powered transport vehicle, contact with electric apparatus. The result of cross-tabulation for agency of accident and hazardous condition is, in sequence, public hazard of passenger vehicle, hazardous method or procedure of temporary structure/building/structure, publit hazard of powered transport vehicle, inadequate guard of temporary structure/building/structure. The result of cross-tabulation for unsafe act and accident type is, in sequence, traffic accident by driving error, fall from elevation by inattention to footing or surrounding, contact with electric current by secure or warn.