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강영석(Kang Young-Seok),김종선(Kim Jong-Sun) 한국체육과학회 2011 한국체육과학회지 Vol.20 No.3
The main aim of this study was to examine the absolute and relative of some commonly used strength imbalance indices such as concentric hamstring-to-concentric quadriceps ratio(Hcon/Qcon : conventional H/Q ratio), eccentric hamstring-to-concentric quadriceps (Hecc/Qcon : functional H/Q ratio). An additional aim was to examine the reliability of the peak torque, total work/body weight(%WT), average power(AP) of the conventional H/Q ratio and functional H/Q ratio measured using the isokinetic dynamometer(Biodex system4, U.S.A). Twenty-three physical active healthy subject(mean±SD, age 22.2±2.1 years, height 173.6±8.7㎝, weight 71.5±9.8, percent fat 19.5±5.9, BMI 23.6±1.7㎏/㎡) were tested 60°/S, 180°/S concentric contraction and eccentric contration. Peak torque(PT) and percent total work(%TW) were significantly different among conventional and functional H/Q ratio, but average power were not significantly different among conventional and functional H/Q ratio. The evaluation of knee joint function by use of isokinetic dynamometer should comprise data on functional and conventional hamstring:quadriceps ratios as well as data on absolute muscle strength. The agonist-antagonist strength relationship strength for knee extension may better described by the more %total work funtional ratios of eccentric hamstring to concentric quadriceps.
비균일 익단 간극을 가지는 축류 압축기의 유동장의 예측
강영석(Young-Seok Kang),강신형(Shin-Hyoung Kang) 한국유체기계학회 2007 유체기계 연구개발 발표회 논문집 Vol.- No.-
Flow structures of an axial compressor with a non uniform tip clearances were predicted by solving in 1-D model developed to easily predict non-uniform tip clearance effect on the flow field of axial compressor. Incidence loss, tip clearance loss were implemented in the model as the major loss sources. Also linear increase in the flow blockage was incorporated in the model. The predicted result showed that flow redistribution is largely dependent on the loss contributions. The strength of the flow perturbation is highly affected by the local flow blockage. These are well reflected on the well known Alford's force distributions.
강영석(Young Seok Kang),박태춘(Tae Choon Park),양수석(Soo Seok Yang) 한국추진공학회 2010 한국추진공학회 학술대회논문집 Vol.2010 No.11
최근 무인기 혹은 소형 항공기들에 대한 수요가 증가함에 따라 소형 터보제트 혹은 터보팬 엔진의 수요가 꾸준히 증가하고 있다. 이러한 소형 엔진은 요구 추력을 달성하면서 크기와 무게를 줄이는 것이 가장 중요한 설계 인자인데, 이는 곧 비추력(Thrust to Weight) 값이 매우 높음을 의미한다. 비추력 값이 높은 엔진을 설계하기 위해서, 압축기 혹은 터빈 등의 핵심구성품의 경우 크기를 줄이고 단수를 줄이는 방법이 가장 효과적이다. 특히 축류압축기의 경우 일반적으로 다단으로 구성하는데 여러 단으로 구성된 압축기 중에서 단수를 줄이고 남은 단에서의 압력비를 높이는 ‘고부하 압축기’를 채용함으로써 이러한 문제를 해결할 수 있다. 최근 국내에서도 축류형 압축기에 대한 개발의 필요성이 꾸준히 제기되고 있으며, 이에 본 논문에서는 고부하 축류형 압축기의 설계 및 성능 리뷰 중 주요한 사항에 대해 소개하고자 한다. Recently, needs for UAVs and small aircraft and small turbo jet or turbo fan engines for these air-crafts are increasing. Size and weight are the two main restrictions in small air-crafts such as UAV or VLJ propulsion system applications. Therefore, high power density is required in small size and designers come up with unconventional solutions in the design of small aero gas turbine engines. One of the solutions is the usage of highly loaded axial compressors. This paper introduces an aerodynamic design method of a highly loaded axial compressor and its review process. Numerical simulation has been carried out to assess the aerodynamic performance of the compressor.