http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
유주식,엄용균,Yoo, Joo-Sik,Eom, Yong-Kyoon 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.6
The problem of phase change from liquid to solid in the inviscid plane-stagnation flow is theoretically investigated. The solution at the initial stage of freezing is obtained by expanding it in powers of time, and the final equilibrium state is determined from the steady-state governing equations. The transient solution is dependent on the three dimensionless parameters, but the equilibrium state is determined by one parameter of (temperature ratio/conductivity ratio). The effect of the fluid flow on the growth rate of the solid in the pure conduction problem can be clearly seen from the solution of the initial stage and the final equilibrium state. The characteristics of the transient heat transfer at the surface of the solid and the liquid side of the solid-liquid interface for all the dimensionless parameters are elucidated.
상향 원형노즐 제트에 의한 하향 등온 원형평면에서의 열전달 현상에 관한 연구
이인재(In Jae Lee),엄용균(Yong Kyoon Eom) 대한설비공학회 2016 설비공학 논문집 Vol.28 No.11
While many studies on the heat transfer effect of an impinging jet have been published, most studies focus on the downward impinging jet. This study investigates the impinging jet heat transfer phenomenon when water at a temperature of 24℃ impinges on the downward isothermal circular plate at 60, 70, and 80℃ and when the upward round jet nozzle is 4, 6, and 8 mm diameter with a flow rate 3.6, 4.6, and 5.6 L/min, respectively, and when the ratio of the nozzle clearance/nozzle diameter (H/D) is 1. The results showed that, as the nozzle diameter decreases, the heat transfer coefficient increases at a constant flow rate. The correlation equation of Nur , Prr , and Rejg is obtained in the impinging and constant velocity flow region (Nur/Prr<SUP>0.4</SUP>)Dr=4.6[Rejg(r/Rc)Dr]<SUP>0.8</SUP> at all flow rates, in the deceleration and falling flow regions (Nur/Prr<SUP>0.4</SUP>)Dr=42.7|Rejg(r/Rc)Dr-345.7|<SUP>0.3</SUP> at 3.6 L/min, (Nur/Prr<SUP>0.4</SUP>Dr=92.4|Rejg(r/Rc)Dr-16.8|<SUP>0.2</SUP> at 4.6 L/min, and (Nur/Prr<SUP>0.4</SUP>)Dr=322.4|Rejg(r/Rc)Dr-536.2|<SUP>0.01</SUP>at 5.6 L/min.
중력방향과 대향류인 저속 원형노즐 제트충돌에 의한 원형평판에서의 열전달 현상
김기태(Ki Tae Kim),엄용균(Yong Kyoon Eom) 대한기계학회 2009 大韓機械學會論文集B Vol.33 No.12
The heat transfer phenomenon was investigated in this study when a circular water jet with low velocity flows to the downward facing heated circular plate and against the direction of gravity. Data are presented for jet flow rate between 0.23 and 2.3 l/min, jet fluid temperature of 24℃, heat fluxes between 345 and 687 W/㎡ , H/D=1, 2 and 3 with a single round jet diameter 2mm. The effects of heat flux, jet velocity and H/D on the local heat transfer are investigated in for the various regions of jet impingement. The local heat transfer distributions are analyzed based on the visualization of jet flow field. Data from experimental results are correlated by expressions of the form Nu=0.01Re<SUP>058</SUP>·Pr<SUP>0.4</SUP>.
넓은 수평 환형 공간에서의 진동하는 자연 대류로의 천이 : Pr=0.1
유주식(Joo-Sik Yoo),김용진(Yong- Jin Kim),엄용균(Yong-Kyoon Eom) 한국전산유체공학회 2000 한국전산유체공학회지 Vol.5 No.3
Natural convection in a wide-gap horizontal annulus is considered, and the transition of flows from steady to oscillatory convection is investigated for the fluid with Pr=0.1. The unsteady stream function-vorticity equation is solved with finite difference method. As Rayleigh number is increased, the steady crescent-shaped flow bifurcates to a time-periodic flow with like-rotating eddies. And afterwards, a transition to an oscillatory multicellular flow with a counter-rotating eddy on the top of the annulus occurs. A transition from steady to an oscillatory flow occurs, but dual solutions and hysteresis phenomena are not observed.
홍삼 제조공정에서 건조 방법과 조건이 제품의 품질에 미치는 영향
김광윤(Gwang-Yun Kim),김기태(Ki-Tae KIM),엄용균(Yong-Kyoon Eom) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
An experimental study has been conducted to analyze the influence of drying methods and conditions on the quality of red ginseng in the manufacturing process. The physical quality of red ginseng depends on the existence of cavity, body color, homogeneity of drying, among others. This study aims to investigate the physical quality of red ginseng under several drying conditions. In the present work, the occurrence of internal cavity is studied for a range of drying temperatures and flow velocities. The drying temperature was varied from 60 ℃ to 80 ℃ for flow velocities of 1 ㎧ and 2 ㎧. Further, for a fixed drying temperature of 65 ℃, the flow velocity was varied from 1 ㎧ to 4 ㎧. The rate of decreasing weight and volume during the drying process under the various drying conditions was measured. It was observed that internal cavity did not occur below 65 ℃ and occurred above 70 ℃ for flow velocities of 1 ㎧ and 2 ㎧. it has been concluded that the best drying conditions for ginseng are at a temperature of 65 ℃ and air velocity of 2 ㎧.
상자식 농수산물 건조기의 유입관에 설치된 유동제어 요소들이 건조실 유동장에 미치는 영향
김광윤(Gwang-Yun Kim),천성국(Sung-Kook Cheon),엄용균(Yong-Kyoon Eom) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
This study aims at developing a highly efficient agricultural product dryer by ensuring uniform flow distribution in the drying room. A theoretical simulation was conducted to analyze the effect of element parts to control the flow in the dryer room. At first, the flow mechanism in the drying room of the existing dryer having four vertical branch ducts is investigated. Secondly, the effect of installing ribs, porous plates and change in the size of air-vent and inflow guides are analyzed. Uniform flow has been accomplished in the drying room with a 14 degrees rib and porous plates. An air-vent ratio of 1:2:3 in vertical branch ducts and the presence of inflow guides in the main ducts can produce a uniform flow in the dryer room.
최대밀도점 부근의 물 속에 잠겨있는 등온 수직 긴원기둥에 의한 자연대류의 실험적 연구
엄용균,권승혜 安東大學校 工業技術硏究所 1996 공업기술연구논문집 Vol.3 No.1
An experimental study of the free convection due to a isothermal vertical long cylinder immersed in water near its density extremum has been carried out. The surface temperature of the cylinder is 0℃, the aspect ratio is 4.8×10^(-2). Time-exposure photographs of the buoyancy-driven flow adjacent to a vertical cylinder in pure water are presented for adjacent water temperatures between 2.0 and 10℃. These conditions are of special interest since between 2.0 and 10℃ the buoyancy force distribution id locally bi-directional across the thermal transport region, Oweing to the density extremum at about 4℃. Resurts of the visualization show three distinct flow regions: upware flow for 2.0℃≤T_(∞)≤4.3℃, downward flow for 5.8℃≤T_(∞), dual flow for 5.6℃<T_(∞)<5.8℃ and unsteady atate flow for 4.3℃<T_(∞)≤5.6℃. The temperature range which the upward flow regions appeared is the same with those of short cylinder, but the temperature which the dualflow region and the downflow region occur is lower than those of short cylinder. Mean Nusselt numbers were smaller at unsteady state region than at the other regions. In the downward flow region, mean Nusselt number increase with increasing the surrounding temperature. In the upward flow region, mean Nusselt number increase and decrese with increasing the surrounding temperature, so there are maxmum Nusselt number at T_(∞)=3.0℃. Comparion of mean Nusselt number with past theoretical study shows good agreement