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여자 창던지기 도움닫기 최종 1보 착지와 릴리즈 국면의 운동학적 분석
홍순모,이영선,김태삼 한국운동역학회 2004 한국운동역학회지 Vol.14 No.1
S. M. HONG, Y. S. LEE, T. S. Kim. The Kinematic Analysis of the Last Stride Landing and Release Phase in the Woman Javelin. Korean Journal of Sport Biomechanics, Vol. 14, No. 1, pp. 51-63, 2004. The purpose of this study was to investigate a three dimensional kinematic variables about the last stride and the release phase of the throwing technique for female javelin throwers. For the motion analysis, Six female javelin throwers were used as subjects. Three-dimensional coordinates were collected using the Kwon3D Motion Analysis Package Version 2.1 Program. Two S-VHS Video Cameras were used to record the locations and orientations of control object and the performances of the subjects at a frequency of 6.0 HZ. After the kinematic variables such as the time, the distance, the velocity, and the angle were analyzed about the last stride and release phase, the followings were achieved; 1. For the effectively javelin throwing, the subjects appeared to do long the approach time in the phasel of landing phase, and short the delivery time in release phase 2. In the release event, the other subjects except for subject A appeared to throwing in the lower condition than the height of themselves. This result showed to slow the projecion velocity. 3. For increase the projection vcelocity of the upper extremity joint in the release event, it appeared to do extend rather the shoulder angle than increase the extension of elbow joint. 4. The body of COG angle showed to gradually increase nearly at the vertical axis in the release event. But the front lean angle of trunk showed a small angle compare to increase of the body of COG angle. Therefore for the effectively momentum transmission of the whole body in the javelin, the front and back lean angle of trunk appeared to do fastly transfer the angle displacement in the arch posture or the crescent condition during the deliverly motion of the release phase.
Exit Flow Measurements of a Centrifugal Pump Impeller
Hong, Soon-Sam,Kang, Shin-Hyoung The Korean Society of Mechanical Engineers 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.9
Discharge flows from a centrifugal pump impeller with a specific speed of 150 [rpm, m$^3$/min, m] were experimentally investigated. A large axisymmetric collector instead of a volute casing was installed to obtain circumferentially uniform flow, i.e. without interaction of the impeller and the volute. The unsteady flow was measured at the impeller exit and vaneless diffuser using a hot film probe and a pressure transducer. The flow at impeller exit showed pronounced jet-wake flow patterns. The wake, which was on the suction/hub side at high flow rate, became enlarged pitchwisely on both the hub and the shroud side as the flow rate decreases. The pitchwise non-uniformity of the flow rapidly decreased along the downstream and the non-uniformity almost disappeared at radius ratio of 1.18 for medium flow rate. The mean vaneless diffuser flow was reasonably predicted using a one dimensional analysis when an empirical constant was used to specify the skin friction coefficient. The data can be used for a centrifugal pump impeller design and validation of CFD codes and flow modeling.
Exit Flow Measurements of a Centrifugal Pump Impeller
Soon-Sam Hong,Shin-Hyoung Kang 대한기계학회 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.9
Discharge flows from a centrifugal pump impeller with a specific speed of 150 [rpm, ㎥/min, m] were experimentally investigated. A large axisymmetric collector instead of a volute casing was installed to obtain circumferentially uniform flow, i.e. without interaction of the impeller and the volute. The unsteady flow was measured at the impeller exit and vaneless diffuser using a hot film probe and a pressure transducer. The flow at impeller exit showed pronounced jet-wake flow patterns. The wake, which was on the suction/hub side at high flow rate, became enlarged pitchwisely on both the hub and the shroud side as the flow rate decreases. The pitchwise non-uniformity of the flow rapidly decreased along the downstream and the non-uniformity almost disappeared at radius ratio of 1.18 for medium flow rate. The mean vaneless diffuser flow was reasonably predicted using a one dimensional analysis when an empirical constant was used to specify the skin friction coefficient. The data can be used for a centrifugal pump impeller design and validation of CFD codes and flow modeling.<br/>
터보펌프 인듀서의 비정상 캐비테이션에 관한 실험적 연구
홍순삼(Soon-Sam Hong),김진선(Jin-Sun Kim),최창호(Chang-Ho Choi),김진한(Jinhan Kim) 한국유체기계학회 2003 유체기계 연구개발 발표회 논문집 Vol.- No.-
Steady and unsteady cavitation characteristics of turbopump inducer were investigated in this paper. To see the effect of blade angle on the inducer performance, three inducers with inlet tip blade angle of 7.8°, 7.0°, 6.1°, respectively, were tested. For 7.8°, 7.0° inducers in the non-cavitating condition, head decreased linearly with flow rate, but head-flow rate curve had a dip at the flow coefficient φ=0.065 for 6.1° inducer. Rotating cavitation and cavitation surge were found in the 7.8°, 7.0° inducers in the cavitation tests. During the rotating cavitation one cell rotated at the same rotational speed as that of the inducer. The cavitation surge did not rotate and the oscillating frequency was 7~20 ㎐. From the curve of the critical cavitation number versus flow rate, it was found that the steady cavitation performance of 6.1° inducer was much lower than that of 7.8°, 7.0° inducers.
75톤급 액체로켓엔진용 터보펌프 조립체의 상사매질 성능시험
홍순삼(Soon-Sam Hong),김진선(Jin-Sun Kim),김대진(Dae-Jin Kim),김진한(Jinhan Kim) 한국추진공학회 2010 한국추진공학회 학술대회논문집 Vol.2010 No.11
추력 75톤급 액체로켓엔진용 터보펌프 조립체 실물형에 대하여 정격 회전수에서 성능시험이 수행되었다. 실매질 대신 상사매질을 사용하였는데 산화제펌프에는 액체질소, 연료펌프에는 물, 터빈에는 고온 공기가 공급되었다. 시험 중 터보펌프는 안정적으로 운전되었으며 성능 요구조건을 만족시켰다. 운전 초기의 회전수 상승구간에서도 펌프의 양정계수와 유량계수는 일정하게 유지되었다. 터보펌프 단품 성능시험과 조립체 성능시험 결과를 비교할 때 펌프 양정계수와 터빈 효율이 두 종류의 성능시험에서 비교적 잘 일치하였다. Performance test of a full-scale turbopump assembly for a 75 ton class liquid rocket engine was carried out at full speed. Model fluid was used as a working medium: liquid nitrogen for the oxidizer pump, water for the fuel pump, and hot air for the turbine. The turbopump was operated stably, satisfying the performance requirements. Head coefficient and flow coefficient of the pumps remained constant at the speed-increasing period. In terms of performance characteristics of pumps and turbine, the results from the turbopump assembly test showed a good agreement with those from the turbopump component tests.