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극초음속 쐐기형 흡입구의 최대 전압력 회복률을 위한 오스와치 기법 분석
허엽,문규환,성홍계 한국항공우주학회 2017 韓國航空宇宙學會誌 Vol.45 No.12
In order to improve the performance of the air breathing engines, it is important to maximize the total pressure recovery through air intake. In this study, we investigated whether the Oswatitsch method, which guarantees the maximum pressure recovery for supersonic intake, is effective at hypersonic speed by compressing the intake air with the same intensity at each ramp. The non-linearity of the shock wave normal Mach number at each ramp stage was analyzed by comparing the compression ramp angle and the number of ramp to the inflow Mach number in terms of compressible thermodynamics and the operation limits of the inlet. Based on this analysis, the Oswaitisch technique yields valid conditions not only in supersonic but also hypersonic flight regime. 공기 흡입식 엔진의 성능 향상을 위하여 흡입구를 통한 유입공기의 전압력 회복률을 최대로 하는 것은 엔진 설계에 있어서 매우 중요하다. 흡입구의 각 램프 단에서 발생하는 충격파의 세기를 동일하게 흡입공기를 압축하면 흡입구에서의 최대 전압력 회복을 보장한다는 Oswatitsch 기법이 극초음속에서도 유효한지를 조사하였다. 극초음속 영역에서의 흡입구 작동 한계를 고려하여 압축 특성 및 열역학적 관점에서 유입 마하수에 따른 흡입구의 압축 램프 각도와 램프 수에 따른 흡입구 성능을 비교하여 각단에서 발생하는 충격파 강도에 영향을 주는 경사 충격파에 수직한 마하수의 비선형성을 분석하였다. 이 분석을 근거로 Oswaitisch 기법이 초음속에서 뿐만 아니라 극초음속 비행 영역에서도 유효한 결과를 도출할 수 있음을 확인하였다.
허엽,박장평 江原大學校附設體育科學硏究所 1994 江原大學校附設體育科學硏究所論文集 Vol.- No.18
The purpose of this study is to find out if there is any effect of knowledge of results on the motor learning. The subjects of this study were sixty middle school girls using the right hand(aged 15.43± .42). The experimental condition was consisted of quantltive KR during 60trials, qualitative KR offer group, quantltive KR during 1 - 30 trials, qualitative KR offer group during 31 - 60 trials, qualitative KR during 1 - 3Otrials, and quantitive KR offer group during 31 - 60 trials, control group. The task of this experiment was timing task and it was to move four sections(90cm) at the rate of 1800msec. The result of experiment;It was find that there's no differences between the group.
단섬유강화 고분자 복합재료의 압축성형에 있어서 섬유배향에 미치는 압축비의 영향
허엽,이상동,김옥만,안종윤,양광영,한길영 조선대학교 생산기술연구소 1996 生産技術硏究 Vol.18 No.1
In this study basic equations of fiber orientations is compared with experimental results. It is found that fiber orientations of short fiber reinforced polymeric composite under compression molding are governed by slope of flow speed in x-y direction. Fiber orientation angle of mold is also found to increase with closure speed and the compression ratio. At the middle of the mold. the slope of flow speed is larger in x-direction than in Y-direction. At the wall of the mold. the slope of flow speed in y-directicn occurs due to the effect of friction. hence affects the fiber orientation. The effect of partial flow. which incurs y-direction orientation causes to increase the fiber orientation angle at the fore part of the flow.