• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.2011-2014
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• 2008

We measured the permittivity and electromagnetic wave propagation velocity of used insulation oil with wide frequency range including ultra-high frequency by time domain reflectometry. The permittivity or propagation velocity is essential for locating discharge faults of oil filled power transformer. We derived 2.21 as a permittivity and $2.03{\times}10^8 m/s$ as a velocity from the measurement of pulse travelling time along a coaxial line filled with used insulation oil or air. The permittivity measurement system we designed shows high measurement accuracy and the convenience for field use.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.393_394
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• 2009

초전도한류기(SFCL)는 고장전류에 대한 초고속 감지, 고장전류 제한이 가능하고, 정상계통에서는 무손실 운영이 가능한 신개념의 기기이다. 공급신뢰도 측면에서 SFCL은, 고장전류 저감으로 송전을 지속할 수 있는 장점이 있는 반면, 기존 계통에 직렬연결되므로 자체 고장으로 인해 공급신뢰도를 악화시킬 수도 있다. 특히, 고속스위치를 필요로 하는 하이브리드형 SFCL의 경우 계통연계 이전에 SFCL 자체의 신뢰성이나 주위 계통에 미치는 영향을 미리 검토해야 한다. 본 논문에서는 SFCL의 신뢰도 데이터를 계산하는 기법과 SFCL 인근 설비의 신뢰도 데이터를 갱신하는 방법에 대해 제시하였으며, 이는 SFCL가 연계된 배전계통의 수용가 공급신뢰도를 산출하기 위해 필요한 사전단계에 해당한다.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.46-49
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• 2004

Switched Reluctance Motor(SRM) has been researched for its superior characteristics. The SRM drive system has simple mechanical and magnetic structure, and it requires simple power electronic drive circuit. It is to be compatible to wide range adjustable speed drive system because it has the same driving characteristics of DC series motor's, easy control principle and high efficiency characteristics. In this paper, 2 types of excitation strategy are researched. Conventional 1-phase excitation and 2-phase excitation method are compared and tested. Though 1-phase excitation method is robust and has high performance, 2-phase excitation method has some merit in appling power device. Some simulation and test results are foaled with some analysis.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.773-774
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• 2005

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.193-196
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• 2007

We developed and tested the high pressure hydrogen gas cylinder(type4) for fuel cell vehicle. The working pressure is 350bar. We conducted material tests, production tests and design qualification tests on the developed cylinders according to modified NGV2-2000(hydrogen). The high pressure hydrogen gas cylinder met all the design qualification requirements of ANSI/CSA NGV2-2000 and acquired NGV2 certification from independent inspection agency.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2007.11a
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• pp.325-330
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• 2007

Uniaxial tensile test are generally much simpler than uniaxial compressive test. Uniaxial compressive test is experimentally more difficult because of the low buckling resistance of a sheet of paper. In order to avoid buckling, many researchers have applied various lateral restraint techniques to investigate paper uniaxial compression behavior. Adding unnecessary force to inhibit compressive deformation of the sheet is unwanted, but sufficient force must be used to inhibit buckling. This study has been carried out to develop new uniaxial compressive standard test method without exerting unnecessary force to paper specimen to prevent buckling.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.472-475
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• 2003

In this paper, insulating varnish has been used for field magnet and armature impregnated insulating material of electric locomotive and traction motor. When it was duplicated coating, it could be accuse internal void, and which could change electrical characteristics. We used to boundary elemental method of simulation tool, and improved optimal insulating design of insulating varnish according to measuring electric distribution in void of specimen.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.629-630
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• 2006

This paper describes a novel sensorless excitation position detecting method of Switched Reluctance Motor(SRM) drive. A suitable excitation pattern of each phases is determined by comparison of detecting current without an inductance estimation. The principle of the rotor position estimation is based on the detection of phase current according to rotor position. This sensorless method is very simple and gives efficient control of drive system. The suggested method is verified by experiments.

• Journal of Digital Convergence
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• v.3 no.2
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• pp.39-57
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• 2005

This research is about continuous improvement in productivity for the central and local government administration. It is a comprehensive execution manual that summarizes from preparation to completion of this task. If you follow the process described in this research, you will achieve the following. l. You will motivate the innovators. 2. You will spare yourself of many trial and errors and risks thus increasing the effectiveness, 3. You will eliminate the obstacles to innovation. 4. You will continue to innovate and will be able to assess the results through visible index.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.1
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• pp.56-59
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• 2008

We have designed 4 types(void in insulation paper, protrusion electrode, floating electrode, surface discharge) of partial discharge(PD) defect to simulate typical faults found in oil filled power transformers. Ultra-high frequency(UHF) radiation due to PD was measured using a UHF measuring system and a conventional PD measuring system, simultaneously. Electromagnetic radiation spectra of these defects show UHF radiation up to about 1.5-2 GHz range. The phase resolved partial discharge(PRPD) patterns of UHF radiation from the PD defects were also measured and the pattern reveals distinct feature for each defect types. The UHF measuring could be used to detect PDs in oil filled transformers and analysis of the PRPD pattern should provide useful information on origin of PD signal.