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정우원(W. W. Jeong),이계한(K. H. Rhee),장안식(A. S. Jang),박경열(K. R. Park),전경진(K. J. Chun) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.5월
When a water jet is injected on the body surface, the pressure and shear stress on the surface are important physical parameters in determining the body surface wash out and physical stimulus. We used the force plate in order to measure the surface average pressure for different nozzle types and distances between a nozzle and a plate. We used the nozzles with a hole dimeter of 1.8, 2.9, 3.2㎜, and the shower heads with 10 holes (hole diameter, 1㎜) and 20 holes (hole diameter, 1㎜). The distances between a nozzle and a plate was 10, 20, 30, 40㎝. The results showed that the surface forces were not affected by the distances between a nozzle and a plate. Further numerical studies will be performed to predict wall shear stress based on the measured pressure data.
정우원(W. W. Jeong),이계한(K. Rhee),박경열(K. R. Park),전경진(K. J. Chun) 한국정밀공학회 2005 한국정밀공학회 학술발표대회 논문집 Vol.2005 No.10월
Analysis of behavior pattern and thermal response during bathing and showering provides important fundamental data when developing an automatic bathing/showering system. The behavior pattern and physiological changes during bathing/showering were measured and analyzed for the aged male group. We recorded the volunteers showering at front, back, left and right view using four CCTV cameras in order to study the behavior pattern during showering, The photographic data were analyzed by counting the frequencies of body contact and identifying zones where hands could reach. In order to study the thermal response, we measured the blood pressure (B.P), heart rate (HR.), body temperature (B.T.), breathing rate (B.R) lor the different water temperatures and the locations of immersion lor the young and old age groups. The results showed that the frequencies of body contacts were varied for different body sections, Also there were some body sections where hands could not be reached because of reduced pliability and muscular strength of the aged group. But we observed rather uniform body contact frequencies when a towel was used. In partial immersion bath experiments, we observed the changes of B.P, H.R and B.T in the case of young and old age groups, and the changes were more significant in the young age group.
유한요소/유한체적법 기반의 상용전산유체역학 프로그램의 유동장 변화에 대한 비교
정우원(W. Jeong),성재훈(J. Seong),이계한(K. Rhee),곽대순(Dai-Soon Kwak) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
Recently, many studies for flow characteristics have used commercial computational fluid dynamics (CFD) software to simulate flow phenomena in various fields. The aim of this study is to contribute to the discussion on the efficiency of finite element (FE) and finite volume (FV) methods, which have mainly used as CFD solvers for situations with the same number of mesh elements and geometries. We compared the accuracy of the results and the flow patterns among three different commercial codes - Ansys CFX, Fluent and ADINA, which are used in many fields. We calculated threedimensional incompressible laminar flow problems with simple pipe and bifurcation models. Our results showed that FEM CFD codes (ADINA) were more influenced by the mesh type and quality compared to FVM CFD codes (Ansys CFX, Fluent). The computation time was found to be significantly shorter for the FVM compared to the FEM codes.