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노즐특성에 따른 MIST-COOLING 열전달에 관한 실험적 연구
이진원,강영규,백병준,박복춘 ( J . W . Lee,Y . G . Kang,B . J . Baek,B . C . Park ) 한국열처리공학회 1992 熱處理工學會誌 Vol.5 No.3
The effect of nozzle characterristics on the mist-cooling heat transfer was investigated under the various flow conditions. Two different types of twin fluid nozzle were used, one is a 90° angle tip nozzle with needle and the other is a 90° angle tip non-needle nozzle. The cooling rate from the heated surface was measured and obtained the boiling curve as a function of surface temperature. An immersion sampling was employed for the measurement of droplet size of the spray. As a result of this experiment, the liquid sheet type nozzle shows better atomization when the mass ratio Mr>2.0, and collects more liquid droplets on the heated surface that results in better cooling effect. It was found that the maximum heat flux and heat transfer coefficient increased with increase in the volumetric flow rate, whereas the maximum heat flux decreased with increase in spray distance. The cooling effect depends upon the amount of collected droplet and droplet size, but it strongly depends upon the amount of collected droplet.
이진원,구재학,김현영,Lee, J.W.,Goo, J.H.,Kim, H.Y. 대한설비공학회 1994 설비공학 논문집 Vol.6 No.1
Particle contamination into and out of a cavity-cylindrical cavities with aspect ratios(width/depth) less than, equal to 1 and langer than 1, and also three dianensional T's attached to a cylindrical flow tube was studied numerically, using a finite difference method. In the process of unsteady particle diffusion, the particles contained in a concentration boundary layer near the tube wall plays an important role in the initial stage, after which a quasi-steady concentration profile is developed inside the cavity, resulting in an exponential change of concentration with time. Average concentration and its rate of change are observed to be closely correlated by a power law function in terms of Reynolds number and the logarithm of Schmidt number. Effects of the three parameters-Re, Sc, and aspect ratio-are analysed and well explained.
다층 Panel Cryoarray를 갖는 Cryopump의 Pumping 특성해석
이진원(J.W. Lee),이영규(Y.K. Lee),최헌오(H.O. Choi) 한국진공학회(ASCT) 1992 Applied Science and Convergence Technology Vol.1 No.3
다층 panel형 cryoarray를 갖는 원통형 cryopump의 정적 pumping 특성을 view factor를 이용한 수치적 방법으로 해석하였다. 해석모델은 단순 원판을 기본으로 하고, 여기에 상향 및 하향의 skirt를 부착한 실질적 array를 대상으로 하였으며, 형상, 크기 및 panel 갯수를 변화시키면서 array 전체의 총 pumping 효율과 array 내의 pumping 속도분포를 모두 구하였다. 다층 panel array에서도 single panel의 경우와 같이 type Ⅲ 개스(He, H₂)에 있어서는 pumping 효율을 최대로 하는 최적의 크기가 있으며, panel 수효가 증가하면 pumping 속도는 약간만 증가하나 총 pumping 용량은 이에 비례하여 증가한다. Skirt의 각도를 상향으로 변화시키면 type Ⅲ 개스의 상대적 pumping속도가 증가되며 type Ⅱ 개스에 의한 cryosorbent의 오염도는 대략 10% 정도이다. Static pumping characteristics of cryopumps with multipanel cryoarray are analysed using the view factor method. Models for analysis are disks with skirts of varying angles, and the shape, size and the number of panels are the parameters varied. Not only the total pumping effeciency but also the distribution of pumping speed in the array is considered. Results show that there exists an optimum array size maximizing the pumping of type Ⅲ gases (He, H₂), and the addition of more panels increases the capacity in proportion but the pumping speed only slightly. Changing the skirt angle upward increases the relative pumping of type Ⅲ gases, and the contamination on the cryosorbent by the type Ⅱ gases is in the order of 10%.
이진원(C.W.Lee),장욱진(W.J.Jang),이장무(J.M.Lee),박영일(Y.I.Park) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.5_2
This paper reviews the time-domain model of Ishihara and transforms it in the frequency domain. The frequency domain model of torque converter can be widely used in designing and analyzing power-train vibration characteristrics. The torque converter on the experiment, has a cut-off frequency below 10Hz as predicted in the numerical calculation.