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Si BJT를 이용한 850MHz용 전력증폭기 설계 및 제작
최현철,김채영,박상욱,이경준,김운동,정백호 경북대학교 전자기술연구소 1995 電子技術硏究誌 Vol.16 No.1
Based on large signal model of Si BJT, two stage power amplifier operating in 850㎒ cellular phone has been designed and fabricated on the microstrip substrate with Photolithography technique. Simulation shows that power added efficiency and output power as 37.4% and 30.5㏈m under the input power of 7㏈m, while the measurement shows these parameters as 38.2% and 27.8㏈m respectively.
전산플랫폼을 이용한 초고층구조물의 감쇠장치 최적화 설계
정보라,이상현,정란,최현철,Joung, Bo-Ra,Lee, Sang-Hyun,Chung, Lan,Choi, Hyun-Chul 한국전산구조공학회 2015 한국전산구조공학회논문집 Vol.28 No.2
본 연구에서는 파라매트릭 모델링 기법을 통해 다양한 대안을 고려할 수 있도록 개발된 StrAuto(이하 전산플랫폼)을 이용하여 감쇠장치에 따른 감쇠비 증가 효과와 풍하중 저감효과를 평가하였다. 비정형 초고층구조물의 수많은 구조시스템 대안 선정을 지원하는 전산플랫폼은 설계자 또는 엔지니어에게 초기 대안을 결정하는데 있어 유용한 도구가 된다. 감쇠장치의 용량 및 추가 요구감쇠비의 크기를 산정하는 과정에서 중요한 원 구조물의 감쇠비에 대한 추정은 풍하중에 대한 실계측 자료를 기반으로 수행된 국내외 관련 연구의 결과를 사용하였다. 감쇠장치는 층간 설치형 수동형 감쇠장치와 질량형 능동형 감쇠장치 두 가지 유형을 고려하였다. 감쇠장치에 의해 추가되는 감쇠비는 FEMA에서 제안한 식을 이용하여 등가 정적 해석을 수행하여 산정하였다. 전산 플랫폼 내부에 감쇠장치의 용량을 최적화하는 알고리즘을 내장함으로써 최적의 감쇠장치 설계안을 자동적으로 도출할 수 있다. 감쇠장치 설치에 따른 물량저감 효과는 풍하중 저감계수로 평가될 수 있으며, 455m 높이의 초고층구조물을 대상으로 제안한 방법의 유효성을 검증하였다. 제안한 방법을 사용하여 비선형 시간이력 해석을 통해 얻어진 지붕층 변위와 층별 전단력을 근사적으로 추정할 수 있음을 확인하였다. In the study, the effects of damping devices on damping ratio increase and wind-load reduction were investigated based on the computational platform, which is one of the parametric modeling methods. The computational platform helps the designers or engineers to evaluate the efficacy of the numerous alternative structural systems for irregular Super-Tall building, which is crucial in determining the capacity and the number of the supplemental damping devices for adding the required damping ratios to the building. The inherent damping ratio was estimated based on the related domestic and foreign researches conducted by using real wind-load records. Two types of damping devices were considered: One is inter-story installation type passive control devices and the other is mass type active control devices. The supplemental damping ratio due to the damping devices was calculated by means of equivalent static analysis using an equation suggested by FEMA. The optimal design of the damping devices was conducted by using the computational platform. The structural element quantity reduction effect resulting from the installation of the damping devices could be simply assessed by proposing a wind-load reduction factor, and the effectiveness of the proposed method was verified by a numerical example of a 455m high-rise building. The comparison between roof displacement and the story shear forces by the nonlinear time history analysis and the proposed method indicated that the proposed method could simply but approximately estimate the effects of the supplemental damping devices on the roof displacement and the member force reduction.
Simulation을 이용한 A-Frame System 작업자의 이동거리 연구
최현철,성상윤,양난규,정동명,장윤석 한국경영과학회 2015 한국경영과학회 학술대회논문집 Vol.2015 No.4
Order picking process is the most time consuming activity in a warehouse which increases the warehousing cost. To address such inefficiency, a variety of automated systems have been developed. Among them, the A-Frame System is an automated order-picking equipment which is used in a warehouse to handle medical supplies and tobaccos. But in a replenishment area of A-Frame, the workers manually perform the task yet. In this reason, there’s a need for research to increase the utilization of workers. This paper analyzes the replenishment tasks by comparing a moving distance between a single-layer A-frame System and a multi-layer A-frame System. To compare the distance, we conduct simulation study considering operational environment and real world order information acquired at a tobacco warehouse.
Simulation을 이용한 A-Frame System 작업자의 이동거리 연구
최현철,성상윤,양난규,정동명,장윤석 대한산업공학회 2015 대한산업공학회 춘계학술대회논문집 Vol.2015 No.4
Order picking process is the most time consuming activity in a warehouse which increases the warehousing cost. To address such inefficiency, a variety of automated systems have been developed. Among them, the A-Frame System is an automated order-picking equipment which is used in a warehouse to handle medical supplies and tobaccos. But in a replenishment area of A-Frame, the workers manually perform the task yet. In this reason, there’s a need for research to increase the utilization of workers. This paper analyzes the replenishment tasks by comparing a moving distance between a single-layer A-frame System and a multi-layer A-frame System. To compare the distance, we conduct simulation study considering operational environment and real world order information acquired at a tobacco warehouse.
제1형 당뇨병 환자에서 병발한 막증식성 사구체신염 1례
최현진,조희연,강주형,양세원,정해일,최용,문경철,하일수,Choi Hyun-Jin,Cho, Hee-Yeon,Kang Ju-Hyeong,Yang Sei-Won,Cheong Hae-Il,Choi Yong,Moon Kyung-Chul,Ha Il-Soo 대한소아신장학회 2005 Childhood kidney diseases Vol.9 No.1
저자들은 당뇨병성 신병증의 자연경과에 맞지 않는 요검사상 이상 소견을 보인 제 1형 당뇨병을 가진 소아에서 신생검을 시행하여 막증식성 사구체 신염을 진단하였기에 보고하는 바이다. Renal diseases other than diabetic nephropathy can occur In diabetic patients. Urinary abnormalities or clinical courses inconsistent with the natural progression of diabetic nephropathy are suggestive of non-diabetic renal diseases and should lead to more extensive investigations. Presence of non-diabetic renal diseases in diabetic patients can alter the treatment plan and the prognosis. We report a 9-year-old girl who had type 1 membranoproliferatiye glomerulonephritis as well as type 1 diabetes mellitus.