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Application of Mechanical Trimming to Hot Stamped 22MnB5 Parts for Energy Saving
최홍석,고대철,김병민,김동환 한국정밀공학회 2014 International Journal of Precision Engineering and Vol.15 No.6
An energy-saving mechanical trimming technology for hot stamped ultra high strength steel sheets is suggested in this study, in whichthe sheet thickness on the desired trim line is reduced by hot half-trimming at the same time as hot stamping, and the half-trimmedpart is subsequently fully trimmed by mechanical trimming. Effectiveness of the proposed process has been investigated by FEsimulationand experiment. In this process, the hot half-trimming depth in hot stamping and the clearance between the punch anddie in mechanical trimming were considered to be the main process parameters determining trimmed surface quality, trimming load,and tool wear. A high-quality trimmed surface, as compared with that produced by conventional cold trimming, can be achieved witha large hot half-trimming depth in hot stamping and small clearance in mechanical trimming. It was also shown that production timeand cost can be reduced considerably by mechanical trimming using hot half-trimming, with low probability of tool chipping andreduced tool wear, as compared to conventional cold trimming and laser cutting processes. Therefore, mechanical trimming using hothalf-trimming as proposed in this study can replace the high energy- and production time-consuming laser cutting process in the massmanufacturing of automotive parts.
Upbanded IS-95A CDMA 망에서 Soft/Softer handoff가 망설게에 미치는 영향분석
최홍석,노종선,박판종 한국통신학회 1998 韓國通信學會論文誌 Vol.23 No.9
핸드오프는 CDMA 망에서 시스템의 성능과 용량 등 망설계에 영향을 미치는 매우 중요한 변수인데 본 논문에서는 1.9GHz대의 주파수대역에서 전자파전파모델, IS-95A에서 권고한 소프트 핸드오프 알고리즘, 그리고 무선망설계 변수에 대한 연구를 통하여 소프트핸드오프가 CDMA 무선망설계에 미치는 영향을 분석하기 위한 시뮬레이션틀을 개발하였다. 이를 이용하여 소프트핸드오프 이득, 소프트핸드오프가 CDMA 시스템 성능과 용량에 미치는 영향등을 종합적으로 분석하였다. 본 셀설계 틀과 분석자료는 PCS와 차세대이동통신과 같은 1.9GHz대역에서의 CDMA 디지털 이동통신환경에서의 무선망설계시에 기지국선정과 시스템 파라미터 최적화 등과 같은 효율적인 무선망설계에 활용될 수 있을 것이다. Handoff is an important parameter for system performance and capacity analysis in CDMA cell planning. In this paper, simulation tool for analyzing the effects of soft handoff on cell planning of CDMA network is developed by studying propagation model in 1.9GHz frequency specrum, soft hadnoff algorithm given by IS-95, and several parameters for CDMA cell planning. By using the tool, soft handoff gain and effects of soft handoff on cDMA system performance and capacity are analyzed. Research results and simulation tool developed in this paper can be used for optimal CDMA cell planning for PCS and IMT-2000 in 1.9GHz frequency spectrum such as locating base station and parameter optimization.