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저압용 vertex tube의 기하학적형상에 따른 에너지 분리특성에 관한 실험적 연구
오동진,류정인 한국에너지학회 2002 에너지공학 Vol.11 No.3
본 논문에서는 압축공기를 작동매체로 한 저압용 vortex tube에 대한 에너지분리 과정을 상세히 연구하였다. 먼저 vortex tube에서 에너지 분리되어 나오는 온공기와 냉공기의 온도변화에 대하여 실험하였고, vortex tube의 안쪽표면의 최대벽면온도 변화와 vortex tube내의 온도분포를 통하여 vortex tube내 유동장에서의 정체점의 위치에 대한 유용한 정보를 얻게되었다. 이를 바탕으로 vortex tube의 최적 길이와 throttle의 형상, sleeve에 따른 에너지분리과정 등을 실험을 통하여 알아보았다. 또한 본 연구에서는 디젤기관의 배기에 적용하기 위한 외통을 사용하였다. 이때 vortex tube에서 나오는 은공기가 180$^{\circ}$돌아 나오면서 vortex tube의 바깥쪽 벽면을 가열하게 된다. 이러한 기하학적 형상을 통하여 에너지분리효과가 증대됨으로 인하여 디젤기관의 배기가스에 적용 시 고온유동의 온도를 높이고자함에 본 연구의 목적을 두고자한다. The process of energy separation in a low Pressure vortex tube with compressed air as a work-ing medium is studied in detail. Experimental data of the temperature of the cold and hot air leaving the vortex tube are presented. The variation of the maximum wall temperature along the inner surface of the vortex tube and the temperature distribution in a vortex tube provide useful information about the location of the stagnation point of the flow field at the axis of the vortex tube. Analysis of the results enabled to find the optimum length of the vortex tube, the optimum shape of the Throttle and the usefulness of the Sleeve. In this study Outer tube is used for the exhaust application. The hot gas flow is turned 180$^{\circ}$and passes the out-side of the vortex tube a second time heating it. From this geometric setup of a vortex tube He effects of energy separation and the prediction of the ignition of Diesel Soot is presented by experimental data.
오동진 대한의학회 2005 Journal of Korean medical science Vol.20 No.5
This study examined intima-media thickness and arterial plaque occurrence in the carotid and brachial arteries in continuous ambulatory peritoneal dialysis (CAPD) patients. The study compared 25 CAPD patients with 25 normotensive age- and sex-matched controls. Intima-media thickness and presence of plaque in carotid and brachial artery were measured three times using high-resolution B-mode echocar-diography. Left ventricular mass was calculated using the Penn Convection equa-tion. Blood samples were obtained to assess levels of phosphorus, total calcium, serum albumin, C-reactive protein, and lipid profiles. Compared to the control group, CAPD patients had greater mean carotid and brachial intima-media thickness, and a higher proportion of subjects with calcified plaques. The left ventricular mass index was higher in CAPD patients with carotid artery calcified plaques compared to CAPD patients without carotid artery calcified plaques. CAPD patients with such plaque were significantly associated with diabetes mellitus, higher C-reactive protein levels and a lower 2-yr survival rate. The present study showed an high prevalence of carotid calcification in CAPD patients and those with such calcification had a greater incidence of diabetes mellitus, higher C-reactive protein levels and left ventricular mass index, and a lower survival rate.
오동진,김명현,Oh, Dong-Jin,Kim, Myung-Hyun 대한용접접합학회 2012 대한용접·접합학회지 Vol.30 No.6
Fatigue cracks in structural components are the most common cause of structural failure when exposed to fatigue loading. In this respect, fatigue crack detection and structural health assessment are very important. Currently, various smart materials are used for detecting fatigue crack and measurement of SIFs(Stress Intensity Factors). So, this paper presented a measurement of SIFs using MFC(Micro Fiber Composite) sensor which is the one of the smart material. MFC sensor is more flexible, durable and reliable than other smart materials. The SIFs of Mode I(K I) as well as Mode II(K II) based on the piezoelectric constitutive law and fracture mechanics are calculated. In this study, the SIF values measured by MFC sensors are compared with the theoretical results.