http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
낮은 Rayleigh값의 B nard Convection 유동장에 주입된 기포의 영향에 관한 연구
엄용균,권기한,Eom, Yong-Gyun,Gwon, Gi-Han 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.12
n a enclosed square cavity occurred B nard convection, the flow phenomena in the surrounding of the bubble attached at the upper cooled solid wall were studied by using a thermo-sensitive liquid-crystal tracer and image processing techniques. This method offers the advantage of measuring the entire flow field in a selected plane within the fluid at a given instant of time in contrast to point by point method like T/C. Quantitative data of the temperature were obtained by applying a colour-image-processing to the visualized image. As the flowing in a bubble, In a bubble size appears the flow phenomena which the direction of flow is reversed in the entire temperature and flow field. The observed phenomena are described with regard to the thermocapillary convection.
최대밀도점 부근의 물 속에 잠겨있는 수직 등온 강선에 의한 자연대류
엄용균,유갑종,Eom, Y.K.,Riu, K.J. 대한설비공학회 1996 설비공학 논문집 Vol.8 No.3
A numerical analysis is carried out to study the two-dimensional steady state natural convection from vertical wires immersed in cold pure water. The surface of the wire is $0^{\circ}C$ unifrom temperature. Results of the analysis are presented for free stream temperature from $0^{\circ}C$ to $25^{\circ}C$ and the aspect ratio N from $5.26{\times}10^{-3}$ to $1.0{\times}10^{-3}$. The effects of the density extremum and aspect ratio on the flow pattern and the heat transfer characteristics are discussed As the aspect ratio N becomes larger, in the range of $1.0^{\circ}C{\leq}T_{\infty}{\leq}4.4^{\circ}C$ and $6{^{\circ}C}{\leq}T_{\infty}{\leq}17^{\circ}C$, the effect of Pr number on the heat transfer is shown to be more significant than the aspect ratio. Investigating into the effect of the density extremum on the heat transfer from wires, the new heat transfer correlations are suggested with the relation of average Nu mumber vs. modified Ra number. Here, the coefficient values C of correlations are presented as the function of density extremum parameter $R^*$. The effects of the density extremum parameter are also discussed.
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
상자식 농수산물 건조기의 열풍 균일분배구조 실현을 위한 유동해석
엄용균,안도원,천성국,서태원 대한설비공학회 2006 설비공학 논문집 Vol.18 No.1
Both the computational and experimental analysis have been conducted in this study to develop the high efficiency agriculture products dryer by the uniform thermal flow distribution in the drying room. It has been developed based on the results of the computation and experiment in the conventional dryer to improve the thermal flow distribution in drying room. The developed dryer can be prevented the local concentration of the heated wind and achieved the uniform flow distribution using the installation of vertical branch ducts, ribs, guide vanes and porous plates. As a result, the developed dryer reduced the fuel consumption up to 15% and the electricity consumption up to 31.5% compared with the conventional dryer.
중력방향과 대향류인 저속 원형노즐제트 충돌에 의한 일정 두께 하향 등온원형평판에서의 열전달 현상
엄용균 한국수소및신에너지학회 2014 한국수소 및 신에너지학회논문집 Vol.25 No.4
The heat transfer phenomenon was investigated in this study when a single round water jet with the low velocity and against the direction of gravity flows to the downward facing Isothermal of definite thickness circular plate. Experimental investigation is performed for a single round jet diameter 4mm, 6mm, and 8mm with the jet velocity 2.4m/s and jet fluid temperature of 24°C, varied the ratio of nozzle clearance/nozzle diameter (H/D)1, 2, 3, 6, and 8, on circular plate isothermal condition with 85°C. The local convection heat transfer coefficient distributions are analyzed based on the visualization of jet flow field. The effects of the diameter of Nozzle, the ratio of H/D and the ratio of nozzle diameter/circular plate diameter on heat transfer phenomenon are investigated. As a results of experiment is obtained correlation equation, Nur = 3.18Re0.55rPr0.4r.
대구경 PP관 절단 작업에서 휠커터의 구조와 회전수가 미치는 영향에 관한 연구
엄용균,권건영,허원권 한국기계기술학회 2019 한국기계기술학회지 Vol.21 No.5
Recently, a Korean company succeeded in manufacturing ∅1500mm, t90 PP double wall pipe with ring stiffness ‘SN26’ for the first time in Korea. For commercialization, the developed productt must be cut to the required length with cutting machine in the continuous manufacturing process. The cutting operation was attempted with the cutting device(∅18″, 120P Wheelcutter for Aluminum, 2100rpm) used for the conventional PE or PVC pipe(∅1200mm, t70). In order to commercialize the developed product, product must be cut to the required length with cutting machine in the continuous manufacturing process. but the cutting operation was failed. The results of observation after processing, The material of the large diameter PP pipe was fused on the surface of the wheel cutter and the wheel cutter was detached. The purpose of this study is to research the effect of wheel cutter structure and rotational speed on cutting work when cutting large diameter PP pipes.
대구경 PP관 절단장치 개발을 위한 휠 커터의 적정 구조와 회전속도에 관한 연구
엄용균 한국기계기술학회 2020 한국기계기술학회지 Vol.22 No.1
In order to commercialize large diameter PP pipes, the cutting work was attempted with the cutting machine(∅18″and AL120 cutter, 2100 r.p.m) used for the conventional PE or PVC pipe(∅1200 mm, t 70), but the cutting work was failed because the material of “PP pipe” melted and sticked to the surface of the wheel-cutter. In order to find the optimal structure and number of blades for wheel-cutters, an experimental investigation the temperature measurement of specimen and wheel-cutter and the visualization of cutted specimen surface and chip shape were carried out during and after experiment. In addition, modelings for cutting and heat transfer mechanisms have been developed for theoretical analysis. The theoretical and experimental results were in good agreement. The results show that the appropriate structure and the rotational speed of wheel-cutter are W60 and 650 rpm for the large diameter PP pipe cutting machine.
엄용균,이인재,김봉윤 한국기계기술학회 2016 한국기계기술학회지 Vol.18 No.5
The quality of garlic productions and reduction of labor cost which are important to overcome price competition against import garlic. Improving to the quality of garlic production and reducing of labor cost, The garlic seed must be planted with the downward positioning of garlic seed root. This research was conducted to develop a crank-link mechanism for planting garlic seed with the downward positioning of garlic seed root. Computer simulation was conducted for developing a crank-link mechanism. A prototype of developing crank-link mechanism was manufactured and laboratory tests was performed. As results, Followings are achievements in range of plant depth = 50~70 (mm) with tolerance depth 3 mm, planting hole size = 45×50 (mm) with tolerance size 5 mm at planting speed 0.3 m/s.