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LDPE에서 공간전하분포와 측정전류의 시간특성에 대한 수치해석
황보승,박대희,남석현,권윤혁,한민구,Hwang, Bo-Seung,Park, Dae-Hui,Nam, Seok-Hyeon,Gwon, Yun-Hyeok,Han, Min-Gu 대한전기학회 2000 전기학회논문지C Vol.52 No.10
In this paper in order to evaluat quantitavely the formation mechanism of space charge and its effects on the conduction characteristics in LDPE we have carried out the numerical analysis on the basis of experimental results of space charge distribution cathode field and current with time which had been simultaneously measured at applied field of 50kV/mm and room temperature. As the models for numerical analysis we employ the Richarson-Schottky theory for charge injection from electrode into LDPE and the band-tail conduction at crystalline regions and the hopping conduction by traps which mainly exist at the interface regions of crystalline-amorphous region for charge transport in LDPE. Futhermore in order to investigate the influence of physical parameters on the time characteristcs of space charge distribution and measured current we have changed the values of trap density activation energies for charge injection and transport and have analyzed their effects.
온도 측정과 분석을 통한 40 mm 장축공동실린더의 열적특성 고찰
신내호(Naeho Shin),정동윤(Dong-Yoon Chung),오명호(Myoungho Oh),유삼현(Sam-Hyeon Yoo),남석현(Seok-Hyun Nam) 한국트라이볼로지학회 2006 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.22 No.4
A simple and effective analysis method is presented for gaining a complete transient temperatures on the internal and external surfaces of a 40 mm gun tube subjected to a series of rapid firings. Two series of temperature data for both Hs and As were measured by using two rapid response k-type surface thermocouples near the firing origin and the muzzle. With other available temperature data, patterns of temperature variations of the gun tube as a function of time variable were driven through complete evaluations of the data. It is found that overall temperature gradients which increase exponentially toward saturation temperature, actually consist of a series of linear temperature gradients corresponding to the firing sequences. Under the similar firing sequences, patterns of temperature variations for both the surface temperatures near the chamber and those near the muzzle were found to have linear temperature gradients with different values and the same response frequencies, i.e. they had peaks and lows in emperatures at the same time. The resultant complete temperature data can be used as the fundamental bases for analysis of thermoelastic properties of the materials such as thermal strian and stress, and for the prediction of cannon tube life-time through calculation of wear rate.
에폭시 몰딩에 의한 부스바 온도 저감 효과에 관한 연구
최진욱(Jin-Wook Choe),이웅엽(Woong-Yeop Lee),남석현(Seok-Hyeon Nam),김진규(Nam?Jin-Gyu Kim) 한국조명·전기설비학회 2018 조명·전기설비학회논문지 Vol.32 No.11
As the number of large buildings and factories that consume a lot of electric power is increased, the use of bus ducts that can flow high current is increasing. The NSPB which is mainly used to connect the transformer and the switchboard has a structure in which a three-phase bus bars are spaced apart in a single metal enclosure. The bus bars are made of bare conductors or conductors coated with an epoxy powder or a heat-shrinkable tube. Bus ducts are required to have insulation characteristics for voltage, temperature characteristics due to current and mechanical characteristics due to short-circuit electromagnetic force. In this paper, temperature characteristics of epoxy molded bus bars were investigated through experiments. The maximum temperature change of the conductor with epoxy molding, the maximum conductor temperature change with the number of conductors and the space when the epoxy molding volume was the same and the maximum conductor temperature change with increasing current were compared.