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Metrizable Spaces에 있어서 Compactness에 관한 연구
李福九 圓光大學校大學院 1982 學位論叢 Vol.8-2 No.-
Metrizable space의 compactness에 대한 一般的인 판정을 주고 그것을 이용하여 funtion spaces의 部分 空間에 대하여 compactness에 관한 Arzela-Ascoli 定理를 考奈하여 나아가서 Metrizable 空間 x가 만약 compact이면 x의 모든 open cover{U_(α)}가 Le-besgiie number λ>o을 가짐은 알려져 있다. 여기서는 compact에 관한 동치명제를 利用하여 이 定理의 역이 戒哀함을 증명하여 본다.
전력계통의 실시간 대칭성분 계산을 위한 알고리즘에 관한 연구
신명철,이복구,성낙환 成均館大學校 科學技術硏究所 1987 論文集 Vol.38 No.1
Nowadays as the power systems have been more complicated and have grown to ultra high voltage, it requires an accurate and high speed relaying scheme to improve the reliablity and stability of power systems for a harmonious power supplying. This paper presents a real-time algorithm for calculating symmetrical components from the distorted transient voltage and current signals in a power system. To compute the sequence components and hence to analyze the nature of the disturbance it is necessary to extract the fundamental frequency signals from the noise-ridden transient signals. The fundamental frequency components are filtered out from the transient signals using discrete Fourier technique. The fundamental frequency components of the 3-phase signals are first extracted using an algorithm based on discrete Fourier transformation and then real-time symmetrical components transformation is applied to obtain the sequence components. The algorithm presented is computationally efficient and fast. Experiment results on artificial transmission line demonstrate the validity of the proposed algorithm.
권명현,박철원,서희석,이복구,신명철,Kwon, Myoung-Hyun,Park, Chul-Won,Suh, Hee-Seok,Lee, Bock-Gu,Shin, Myong-Chul Korean Institute of Intelligent Systems 1998 한국지능시스템학회논문지 Vol.8 No.5
Power transformer protective relay should block the tripping during magnetizing imrush and rapidly operate the tripping during internal faults. But traditional approaches maloperate in the case of magnetizing inrush with low second harmonic component and internal faults with high second harmounic component. To enhance the fault detection sensitivities of conventional technuques, flux-differential current derivative curve by fuzzy theory approaches is used. This paper deals with fuzzy logic based protective relaying for power transformer. The proposed fuzzy based relaying algorithm consisits of flux-differential current derivative curve, harmonics restraint, and precentage differential characteristic curv. The proposed relaying was tested with relaying signals obtained from Salford EMTP simulation package and showed a fast and accurate trip operation.