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Bi계 고온초전도체 2223상의 생성과 미세조직에 미치는 하소회수와 소결시간의 영향
주광철,이완재 한양대학교 공학기술연구소 1995 공학기술논문집 Vol.4 No.1
The Bi-Sr-Ca-Cu-O system precursor powders were synthesized by the thermal decomposition of an organic acid salt to get the homogeneous composition. These powders were milled by a planetary mill to make them fine grains. After milling, calcination was carried out at 750℃ for 8 hours in air. The milling and calcination were repeated twice. The grain size and shape were examined by Laser particle size analyzer and SEM. Annealing was done at 860℃ for 20, 40, 60 hours in air. The Tc of specimens annealed at 860℃ for 60 hours were measured with changes of resistance by a DC four-probe method. The results attained were as follows ; 1) The synthesized powders were fine and homogeneous in composition. 2) The finer the grain size the faster the grain growth during annealing. 3) Bi-2201 phase was produced by the calcination. 4) Bi-2223 phase formation was suppreseed by the excess absorption of oxygen. 5) The production of high-Tc 2223 phase was expected by controlling the annealing atmosphere, time and cooling rate.
한국 표준으로 제안된 GCR에 의한 임펄스 응답특성에 관한 연구
권병헌,주광철 한국통신학회 1996 韓國通信學會論文誌 Vol.21 No.4
This paper presents an impulse response of the multi-path channel using KS-GCR(Korean Standard Ghost Cancel Reference) signal. Using the property of the KS-GCRsignal, we can get the impulse response of the multi-path channel from circular cross correlation of the received DS-GCR signal and the orginal KS-GCR ternary sequence. Therefore impulse response of the multi-path channel can be used to design the the ghost cancellation filter if it is designed to have inverse characteristics of multi-path channel. This paper shows that the ghost occurred from the multi-path channel can be cancelled by using the impulse response and preceding ghost cancellation algorithm.