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기지국 어레이 안테나와 불완전 전력 제어를 고려한 DS/CDMA 셀룰라 시스템의 성능 분석
김형채,김항래,김남,한태영,kim, Hyoung-Chae,Kim, Hang-Rae,Kim, Nam,Han, Tae-Young 한국전자파학회 2001 한국전자파학회논문지 Vol.12 No.5
본 논문은 다중접속 간섭을 효과적으로 제거할 수 있는 기지국 어레이 안테나를 이용하여 전파음영 환경하에서 빔 형성 알고리즘과 전력 제어 오차에 따른 DS/CDMA 셀룰라 시스템의 역방향 링크에 대한 성능을 분석한다. 블로킹(blocking) 확률을 어레이 파라미터와 E$_{b}$/N$_{o}$ 및 간섭 통계를 이용하여 유도하고 특정한 블록킹 확률에 일치하는 시스템 용량을 계산하다. 1%의 블록킹 확률을 가정하였을 경우, 동방성 안테나 1개를 사용하는 경우보다는 12개의 어레이 안테나를 이용한 MCGM 알고리즘을 사용하였을 경우에 약 32배의 시스템 용량이 증가함을 보인다. In this paper, the reverse link performance of a imperfect power controlled DS/CDMA cellular system that uses a base station array antenna which can effectively remove the multiple access interference is analyzed considering both beam forming algorithm and power control error in shadowing. The blocking probability of the DS/CDMA cellular system based on array parameters, $E_b/N_o$ and statistics of interference is derived, and then the system capacity corresponding to a certain blocking probability is calculated. On the assumption that the blocking probability is set 1%, the system capacity using MCGM algorithm with 12 antenna arrays is more increased maximum 32 times than that using a omni-directional antenna and about 2 times than that using MMSE algorithm, respectively.
사출성형에서의 Penalty Formulation 을 이용한 Packing 과정 해석
강성용(Sung Yong Kang),김승모(Seung Mo Kim),김선경(Sun Kyung Kim),이우일(Woo Il Lee),김대환(Dae Hwan Kim),김우규(Woo Kyu Kim),김형채(Hyung Chae Kim) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
The penalty method has been widely applied to analyses of incompressible fluid flow. However, we have not yet found any prior studies that employed penalty method to analyze compressible fluid flow. In this study, with an eye on the apparent similarity between the slight compressible formulation and the penalty formulation, we have proposed a new approximate approach that can analyze compressible packing process using the penalty parameter l. Based on the assumption of the isothermal flow, a set of reference solutions was obtained to verify the validity of the proposed scheme. Furthermore, we have applied the proposed scheme to the analysis of the packing process of different cases.
디지털 프린터에 적용되는 회전 다각형 디스크의 소음특성
조준현(Jo, Jun-Hyeon),김형채(Kim, Hyeong-Chae) 한국소음진동공학회 2008 한국소음진동공학회 논문집 Vol.18 No.6
Consumer's product selection measures are being shifted from the units' operational performance to overall performance. Low noise, low vibration, and low power consumption rate, etc. which used to be additional quality indices, now become vital performance factors. Especially, noise and vibration characteristics are being considered as equivalent to/or even more critical than operational performance in certain products such as office machines and home entertainment systems, which share the same space with human being's daily life. Therefore, noise reduction and sound quality improvement technology becomes an inevitable design issue for those applications. Qualitative noise characteristics of rotating polygonal disk applied to digital printer systems are presented. Overall sound pressure level change and tonal noise variation with respect to the geometrical properties of polygonal disk, operational speed, and others are briefly discussed based on experimental results.
온도에 의한 광주사장치의 인쇄화상변동 분석을 위한 CAE 기법
유병호(ByoungHo Yoo),김태규(TaeGyu Kim),김형채(HyeongChae Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
One of the major factors related to printed image quality is the robustness to the environmental temperature inside laser printer. The vital part out of these modules is the Laser Scanning Unit, which has thermal sources inside and made of plastic materials with high thermal expansion coefficient. In this study, mold-injection process of plastic material, thermal deformation of structure, and geometrical optics are involved. A numerical study procedure is developed to evaluate the robustness and error of printed image caused by thermal deformation of laser scanning unit.