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Effect of Mixing Ratio of Biodiesel on Breakup Characteristics of a Single Droplet
( Yop Kim Sa ),( Sung Wook Park ),( Kian Sung ),( Haeng Mook Cho ),( Chang Sik Lee ) 한국액체미립화학회 2005 한국액체미립화학회 학술강연회 논문집 Vol.2005 No.-
In this paper, the breakup characteristics of a single droplet were analyzed as a function of mixing ratio of bioidesel. In order to investigate the effects of high surface tension and viscosity of biodiesel on the breakup mechanism of single droplet, the experiments were performed at various mixing ratios of biodiesels. In addition, the physical properties such as density, kinematic viscosity and surface tension of the biodiesel blended fuels were measured to study the relations between the non-dimensional numbers such as Weber number and Reynolds number, and the breakup mechanism. The experimental apparatus consisted of a droplet generation system, an air flow nozzle, a light source, a long distance microscope and a CCD camera. In the first stage breakup region, the droplet deformation rate was measured in order to reveal out the effect of high surface tension and kinematic viscosity on the deformation of a single droplet. The results of this experiment showed that the higher surface tension and viscosity of biodiesel prevent the disintegration of liquid droplet. Also the breakup mechanism is transited at higher relative velocity as the mixing ratio is increased.
요가 프로그램 수강생들의 스포츠사회화 요인 및 사회적 지지의 관계
김사엽(Kim Sa-Yop),김덕임(Kim Deog-Im) 한국체육과학회 2009 한국체육과학회지 Vol.18 No.1
This study inquires into the relationship between Yoga program trainees’ sports socialization factors and social support. The subjects of the study are those men and women who were participating in Yoga programs of Yoga institutes in the location of Gangwon-do Youngdong region 2008. Stratified Cluster Random Sampling was applied to take out samples. After collecting the response-completed data to the questionnaire, only trustworthyestimated data were encoded. After inputting encoded data individually into computer, standard multiple regression analysis was carried out through the statistics program SPSS 14.0 version for Windows in order to verify the relationship between Yoga program trainees’ sports socialization factors and social support (α=.05). The research method and findings above brought forth the following conclusion: Some relationship was found between Yoga program trainees’ sports socialization factors and social support.
( Yun Jung Oh ),( Sa Yop Kim ),( Bong Woo Ryu ),( Mun Soo Chon ),( Chang Sik Lee ),( Sung Wook Park ) 한국액체미립화학회 2010 한국액체미립화학회 학술강연회 논문집 Vol.2010 No.-
This paper describes the grid-size dependency to calculated DME (Dimethyl ether) spray characteristics such as spray tip penetration, overall SMD and vaporized mass. In order to reduce grid-size dependency, improved droplet-gaseous phase coupling model was suggested. The present EMC (Enhanced Momentum Coupling) model uses weighting factor in estimating momentum transfer from liquid spray to ambient gas. Calculations were performed by using improved KIVA-3V code and the results were compared to experimental results in order to verify the present EMC model. The computational results showed that conventional Eulerian-Lagrangian method predicts different results depending on the grid size. These discrepancies were caused by inaccurate momentum coupling between liquid and gas phase and collision probability predicted by the standard collision model. On the other hand, EMC model significantly reduced the grid-size dependency by modifying the momentum transfer rate effectively according to the grid-size. In addition, the Nordin`s collision model successfully eliminates the impractical probability sensitive to the grid cell volume.
가스 제트 모델을 이용한 DME 분무 해석의 격자 의존성 저감
오윤중 ( Yun Jung Oh ),김사엽 ( Sa Yop Kim ),이창식 ( Chang Sik Lee ),박성욱 ( Sung Wook Park ) 한국분무공학회 2010 한국액체미립화학회지 Vol.15 No.4
This paper describes the grid-size dependency of the conventional Eulerian-Lagrangian method to spray characteristics such as spray penetration and SMD in modeling DME sprays. In addition, the reduction of the grid-size dependency of the present Gas-jet model was investigated. The calculations were performed using the KIVA code and the calculated results were compared to those of experimental result. The results showed that the conventional Eulerian-Laglangian model predicts shorter spray penetration for large cell because of inaccurate calculation of momentum exchange between liquid and gas phase. However, it was shown that the gas-jet model reduced grid-size dependency to spray penetration by calculating relative velocity between liquid and ambient gas based on gas jet velocity.