• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.217-223
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• 1996

혼합증기(수증기/공기)의 막응축 열전달 계수를 수직한 벽면에서 측정하고 상관식을 개발하였다. 열전달 상관식은 액막측과 증기측으로 구분하여 만들었고, 액막측 전열계수의 상관식은 액막의 Reynolds수와 Prandtl수의 함수로 나타냈으며, 증기측 전열계수의 상관식은 증기의 Reynolds수, Prandtl수, Schmidt수 및 공기의 질량분율, 액막 Reynolds수의 함수로 제안하였다. 응축 액막의 두께와 확산층의 순간온도 측정결과로부터 액막의 파형 계면이 확산층에서의 열 및 물질전달에 큰 영향을 끼치고 있음을 확인하였고, 증기측 전열계수의 상관식에 포함된 액막 Reynolds수가 파형 계면의 영향을 반영하고 있다.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.23.2-23.2
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• 2005

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.1
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• pp.25-29
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• 2001

A study has been conducted to investigate the effect of the heat transfer surface position in the range of dropwise condensation, filmwise condensation, and glacial condensation. For dropwise condensation promoter, the heat transfer surface was evaporated by gold. As a result, heat transfer rate is almost same where the position of heat transfer surface is between 45 and 135 degree. It is found that heat transfer rate was reduced as subcooled degree was increased. And it is also found that if the subcooled degree becomes lower, the position of heat transfer surface is more effective. Adversely, if the subcooled degree becomes higher, the effectiveness of surface position is getting relatively lower. Regardless of the position, the transition temperatures from dropwise condensation to filmwise condensation is in the vicinity of 80K.

• Nuclear Engineering and Technology
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• v.17 no.1
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• pp.45-52
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• 1985

A two inverted U-tubes condenser was constructed from transparent materials to study the heat removal capability of steam generators under filmwise reflux condensation mode. Essentially, two sets of experiments were performed: (1) the first dealt with the reflux condensation length, and (2) the second dealt with the flooding points with and without the presence of a noncondensible gas in the steam flow, and the effect of the flooding time. In addition, experimental results are compared with the predictions of analytical models.

• Membrane Journal
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• v.13 no.4
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• pp.246-256
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• 2003

For the olefin recovery from polyolefin off-gas, the permeation behaviors of olefins and nitrogen were investigated through three kinds of PDMS membranes - cross-linked PDMS membranes, a polysiloxaneimide membrane, and oligo-PDMS modified PDMS membranes. Their pure gas permeabilities were measured as a function of operation temperature(-20 to $50^{\circ}C$) and pressure(1 to 25 atm) with ethylene($C_2\;H_4$), propylene($C_3\;H_6$), butylene($C_4\;H_8$), and nitrogen($N_2$) gases. The permeabilities of olefins and nitrogen highly depended upon the nature of PDMS membranes. Among these membranes, cross-linked PDMS membranes showed stable and high olefin/nitrogen selectivities over a wide operation pressure range and further study in various test conditions. Their permeability of olefin and nitrogen were governed by the condensation temperature(solubility selectivity) and plasticization, not the order of the size(diffusivity selectivity) of gases, which matched well with the general permeation behavior of rubbery polymeric membranes for condensable and non-condensable gases. With increasing feed pressure or decreasing feed temperature, the permeabilities of more condensible olefins increase highly, presumably due to high solubility and plasticization, but that of non-condensible nitrogen decreases slightly and thus, the selectivities of olefin/nitrogen increase highly.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.3
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• pp.387-394
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• 1985

본 연구에서는 액체막의 분산현상에 관한 기존의 연구결과들을 토대로 하여 주위 기체의 응축이 액체막의 분산현상-즉, 분산기구와 액체막의 길이(breakup length )에 미치는 영향을, 여러 형태의 노즐에서 분사되는 액체막의 유속과 온도를 변화시켜 가면서, 알아보고자 한다.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.1
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• pp.25-30
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• 2000

In present paper, mass transfer over a flat plate with film condensation including noncondesable gas is analyzed with the help of similarity methods. Couette flow was assumed in liquid film and boundary-layer approximation was used in the ambient flow. Governing equations were transformed into the ordinary differential equtions by the similarity methods. Runge-Kutta and shooting method were used in order to fine the effect of mass transfer on the velocity and concentrations at the liquid-vapor interface.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.517-524
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• 2018

This purpose of this research is to observe the influence of non-condensable gas (NCG) on a horizontal super-hydrophobic aluminum tube and compare it with a bare aluminum tube. To achieve super-hydrophobic characteristics, an aluminum tube was coated with a Self-Assembled Monolayer (SAM). The overall heat transfer coefficient U was used to represent the condensation performance. The NCG mass fraction was the main variable, and its range was 0.08 to 0.45. The condensation performance of the SAM tube and bare tube increased with decreasing mass fraction of NCG. The SAM tube showed 1.9 to 2.5 times larger dropwise condensation performance than the bare tube. When the mass fraction of NCG decreased in the SAM tube, the rate of increase of the SAM tube was lower because flooded condensation occurred. In addition, filmwise condensation occurred in the SAM tube when more active condensation was generated, and its performance was lower than that of the bare aluminum tube. The flooded and filmwise condensation in the SAM tube is explained by the pinning effect. In conclusion, controlling the condition of the condenser is necessary to improve the condensation performance by surface modification a SAM.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.10
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• pp.1380-1387
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• 2000

The existing theoretical models for steady two-dimensional free convective laminar film condensation of pure saturated or superheated vapor under atmospheric pressure on isothermal vertical wall have been reviewed. To investigate the effects such as inertia, thermal convective and liquid-vapor interface shear stress, the models of constant or variable properties in liquid film for condensation of saturated vapor are compared in detail with Nusselt model. Also, for condensation of superheated vapor, the effects of superheated temperature and variable properties in liquid and vapor layers are examined and then a new correlation is proposed to predict the heat transfer. The results are in good agreement with the Shang's correlation within 2% errors.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.31-36
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• 2000

The existing theoretical models for steady two-dimensional free convective laminar film condensation or pure saturated or superheated vapor under atmospheric pressure on isotheraml vertical wall have been reviewed. To investigate the effects of inertia, thermal convective and liquid-vapor interface shear stress, the models of constant or variable properties in liquid film for condensation of saturated vapor are compared in detail with Nusselt model. Also, for condensation of superheated vapor the effects of superheated temperature and variable properties in liquid and vapor layer are examined and then new correlation is proposed to predict the heat transfer. The results are in good agreement with the Shang's correlation within 2% errors.