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EMTP를 이용한 362kV Gas VT의 철공진제거를 위한 가포화리엑터의 파라미터 선정
최재구,김익수,박경원,송희석,Choi, Jae-Gu,Kim, Ik-Soo,Park, Kyoung-Won,Song, Hee-Suk 대한전기학회 2001 전기학회논문지C Vol.50 No.4
Recently, the construction of gas insulated substation(GIS)s has been increased in Korea. But, the whole quantity of the VTs which were used in GIS has been imported. Under the circumstance that $SF_6$ gas power apparatus are being developed up to 800kV rating in Korea, the development of EHV $SF_6$ gas VT is essential for localizing the power apparatus. As for EHV VT, destructive ferroresonance can be generated due to the combination of capacitiances between poles of circuit breaker, ground capacitance of bus and nonlinear excitation property of VT core. But the theoretical analysis about ferroresonance has not been fully achieved in Korea. Therefore, in this paper the authors would like to contribute for localizing EHV $SF_6$ gas VT by developing the diagram of ferroresonance zone according to the parameters of the circuit and the saturable reactor.
최재구,Choi, Jae-Gu 한국환경보건학회 2007 한국환경보건학회지 Vol.33 No.5
The livestocks are sometimes infected with pathogenic microorganisms such as bird influenza, brucellosis, pig cholerae, and salmonella. However, it is difficult to predict the outcome of these diseases because the livestocks are mostly raised in the rural areas. Efficient systems for detecting and alerting the onset of livestock diseases are urgently required. In these studies, the fluorescent analysis method, luminescent analysis method, and frequently used gene amplification method (polymerase chain reaction) have been developed in order to detect the pathogenic microbes in the early stages of disease progression. By using these developed systems, damages due to the livestock diseases induced by microbes can be minimized. If we can detect livestock diseases in the early stage, the costs for diagnosis and treatment will be reduced, and the livestock can be quickly recovered.
최재구(Jae Gu Choi),석창성(Chang-Sung Seok),위성욱(Sung Uk Wee),정의석(Eui-Suck Chung),윤병관(Byoung-Gwan Yun),권석환(Suk-Hwan Kwon) Korean Society for Precision Engineering 2019 한국정밀공학회지 Vol.36 No.3
Isothermal low cycle fatigue (LCF) behavior of a crystal nickel-based superalloy CMSX-4, a material for high-pressure turbine first stage rotor blade, was investigated at elevated temperatures. Strain-controlled LCF tests were performed under various test conditions, such as mechanical strain amplitude. Stress response and cyclic deformation were investigated, and equations of LCF life prediction were derived through the Coffin-Manson method. In addition, fatigue-induced fracture mechanism and microstructural evolution were investigated, using scanning electron microscopy (SEM). Results revealed that cyclic behavior of the CMSX-4 superalloy, was characterized by cyclic softening with increasing number of cycles at 800oC and 900oC. LCF of the CMSX-4 superalloy at 800oC and 900oC could be affected mainly by elastic damage in fatigue processing. Fatigue cracks were initiated in the surface oxide layer of the specimen. The plane of fracture surface was tilted toward <001> direction. The fatigue fracture mechanism was quasi-cleavage fracture at 800oC and 900oC. In all broken specimens, the γˊ phase morphology maintained cuboidal shape.