• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.68-73
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• 2011

This study was performed numerical analysis in order to analyze liquid film flow of heat exchanger tube arrangement and configuration of evaporative multi effect distillation system using medium-temperature. Simulation was accomplished the two-dimensional calculations using commercial analyses program FLUENT based on the FVM(finite volume method). Fresh water generator of this study used Shell & Tubes heat exchanger with Cu_Ni tube, configuration of tube used bare tube and corrugated tube, and arrangement of tube used in-line array and staggered array. Performance of heat exchanger through the formation of liquid film was compared and analyzed. Liquid film flow occurred that falling on heat exchanger tube wall. Result of simulation showed that liquid film thickness of in-line arrangement was found 0.57mm with bare tube and 0.67mm with corrugated tube, respectively. And liquid film thickness of staggered arrangement was found 0.39mm with bare tubes and 0.62mm with corrugated tubes, respectively. Liquid film thickness of corrugated tube showed thicker than bare tube, but heat transfer rates of corrugated tube showed higher than bare tube. The reason was considered that surface area of corrugated tube was wider than bare tube. And liquid film thickness of staggered arrangement showed thinner than in-line arrangement, so thermal performance of staggered arrangement showed higher than in-line arrangement.

• Laser Solutions
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• v.10 no.1
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• pp.19-27
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• 2007

Previous studies demonstrated that laser ablation under transparent liquid can result in ablation enhancement and particle removal from the surface. Although the ablation enhancement by liquid is already known for semiconductor and metal, the phenomena of polymer ablation have not been studied. In this work, tile liquid-assisted excimer laser ablation process is examined for polymer materials, such as polyethylene terephthalate (PET), polymethyl methacrylate (PMMA) with emphasis on ablation enhancement and surface topography. In the case of PET and PMMA, the effect of liquid is analyzed both for thin water film and bulk water. The results show that application of liquid increases the ablation rate of PMMA while that of PET remains unchanged even in the liquid-assisted process. However, the surface roughness is generally deteriorated in the liquid-assisted process. The surface topography is found to be strongly dependent on the method of liquid application, i.e., thin film or bulk liquid.

• Journal of ILASS-Korea
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• v.11 no.4
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• pp.212-219
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• 2006

The initial film flow development of the high-pressure swirl spray was investigated at different injector operating conditions to analyze film flow development and to provide the input data for the modeling works. This result can be also useful to verify the previously simulated results. The initial flow conditions such as liquid film thickness, flow angle and flow divergence are obtained by visualizing the inside and near the nozzle flow with a microscopic imaging system. The visualized images are quantified using an image processing tool. From the information of liquid film thickness and flow angle, the initial axial and tangential velocity and the swirl number of the swirl spray are successfully determined at various operating conditions. The experimental results showed that the initial liquid film thickness, flow angle and flow divergence are remained constant when the injection pressure is increased. However, initial film conditions are severely changed when the fuel temperature is increased. The swirl number remained constant when the injection pressure is increased while it showed increased value at high fuel temperature condition.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.3
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• pp.33-44
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• 1983

This paper deals with the experimental study on the behavior of fuel (methanol) in intake manifold by using the basic apparatus which is manufactured the visible straight tube type model. In this study, the new device for liquid film thickness measurement and vaporization rate measurement are introduced to investigate the variation of liquid film thickness along the intake manifold and to observe the effect of vaporization of injected fuel. the results are summarized as follows: 1) The vaporization rate increases in proportion to decreasing of throttle valve angle and growing air fuel ratio. 2) The liquid film thickness along the intake manifold is mostly independent for the throttle valve angle in low air velocity and then affected in high air velocity, but the distribution of the liquid film thickness on circumferential position almost constant in the region of 300mm down stream from carburetor. 3) The mean liquid film thickness is 0.04 - 0.18mm in case of methanol in the region of air velocity Va = 12m/s - 55m/s and decreases with decreasing the throttle valve angle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.251-255
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• 2005

By using liquid film thickness measurement the spray characteristics of swirl injector according to the geometric parameters were investigated in this paper. A specially designed injector having a variable backhole length, swirl chamber length, orifice length was used to measure the liquid film thickness. The spray characteristics of the injector were represented by mass flow rate according to the injection pressure, liquid film thickness in the lower orifice, spray cone angle.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.879-882
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• 2008

The discotic liquid crystal in compensating film used for the viewing angle improvement of the twist nematic liquid crystal display panel is analyzed. For the optical characterization of the compensating film, we measured the polarization state of the light passing through the film as the tilt angle and the azimuth angle of the film were varied, and then we compared the measured polarization state with the calculated one. Finally we suggested the best fit configuration of the discotic liquid crystal.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.2
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• pp.70-77
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• 2006

A specially designed in;ector using electric conductivity was used to measure the liquid film thickness exactly, The measurement conducted through the precise calibration, accuracy is demonstrated in comparison with the previous theory and the results using other measurement method. The variation of internal flow and stability are examined through the variation of liquid film thickness by the time. The tendency of liquid film thickness for geometric parameters was examined by the precise measurement.

• Transactions on Electrical and Electronic Materials
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• v.7 no.6
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• pp.301-304
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• 2006

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of the SiC (Silicon Carbide) thin film. The SiC thin film exhibits good chemical and thermal stability. The good thermal and chemical stability make SiC an attractive candidate for electronic applications. A vertical alignment of nematic liquid crystal by atomic beam exposure on the SiC thin film surface was achieved. The about $87^{\circ}$ of stable pretilt angle was achieved at the range from $30^{\circ}\;to\;45^{\circ}$ of incident angle. Consequently, the vertical alignment effect of liquid crystal electro-optical characteristic by the atomic beam alignment method on the SiC thin film layer can be achieved.

• Journal of ILASS-Korea
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• v.3 no.2
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• pp.14-23
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• 1998

The negative pressure as much as 10's mmHg is demanded at nozzle inside, in case of atomizing the large density molten materials. by conventional air jet nozzle. In this study, suction type fluid nozzle is designed by applying the ejector principle in order to clarify the air flow of nozzle inside, mechanism of liquid suction and liquid film formation. The results of this experimental study areas follows. Suction force of liquid is magnified by using liquid nozzle, and it is able to supply the liquid stable. Negative pressure at nozzle inside is varied by throttle angle of liquid nozzle, position and outer diameter of air jet nozzle, and have a influence on liquid suction quantity and liquid film formation.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2291-2296
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• 2007

Thermal transport from vertical heated surface to falling liquid film in a channel has been investigated experimentally. Air-flow is introduced into channel to make a counter flow against falling liquid film. This problem is of particular interest in the design of direct contact heat exchange system, such as cooling tower, evaporative cooling system, absorption cooling system, and distillation system. The effects of channel width and air flow rate on the heat transfer to falling liquid film are studied in detail. The results obtained indicate that heat transfer rate is gradually decreased with an increase in the channel width without air flow as well as with air flow in a channel. It is also found that heat transfer rate of air-flow is increased while heat transfer rate of falling liquid film is decreased with an increase in the air flow rate at a given channel width. However, total heat transfer rate form the heated surface is increased as the air flow rate is increased.