• Journal of the Korean Society of Visualization
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• v.16 no.3
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• pp.47-51
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• 2018

The stable deposition of impinging droplets on non-wetting substrates is of great importance for numerous industrial and scientific applications such as coating techniques, inkjet printing, spray cooling of heated surfaces. In this work, we systematically investigate impinging behaviors of non-Newtonian and viscous droplets ejected by electrohydrodynamic atomization.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.148-148
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• 2013

본 연구에서는 스퍼터링(sputtering)에 의해 Mg 함량을 달리하여 제작한 Al-Mg 합금막의 열처리 유 무별 부식 및 방식 거동을 확인하고자 내식성 평가 및 분석을 실시하였다. 내식성 평가는 염수분무시험을 통해 이루어졌으며, 염수분무시험 후 생성된 부식생성물은 SEM, EDS, XRD 평가 기법을 이용하여 초기 중기 후기 단계로 나누어서 분석을 실시하였다. 이상의 결과를 통해서 부식 진행 단계 별로 내식성에 미치는 부식생성물의 영향을 확인할 수 있었으며, Mg 함량에 따른 열처리 유 무 별 Al-Mg 합금막의 방식 메커니즘을 규명할 수 있었다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.180-186
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• 2012

A water-flow test for acceptance verification is carried out for a nonimpinging-type injector prior to the design-performance verification of 70 N-class liquid-rocket engine under development. It is observed that there exist varying characteristics of atomization among the injector-orifices caused by a fabrication crudeness of orifice holes which can be judged from a microscopic standpoint. The flow shedding phenomenon and ruffle on the surface of liquid column (or droplet) could be caught from the instantaneous spray images.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1996.11a
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• pp.10-10
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• 1996

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.12
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• pp.1151-1159
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• 2012

Spray visualization and computer simulation of a DME injector have been conducted to investigate the enlarged injection hole diameter effect. To increase the reliability of the computational result, simulation results have been compared with the visualization test results, and the behaviors of a DME spray under various high-pressure and -temperature conditions have been computed. This study shows a discrepancy of 3.57% between the experimental and the computational results of penetration length for an injection pressure of 35 MPa and ambient pressure of 5 MPa. When simulating the engine conditions, the maximum penetration length of a fully developed DME spray is 42 mm when the temperature to pressure ratio is 300 K/MPa. The DME spray behavior is dominantly affected by the ambient pressure under the condition that the ratio is less than 300 K/MPa, and by the ambient temperature under the condition that the ratio is more than 300 K/MPa.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1317-1322
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• 2004

In this report, the heat transfer model of spray cooling on hot surface was developed by focusing on the effect of rebound motion of droplets. In the model, it was assumed that droplets rebound repeatedly on the hot surface and heat transfer upon droplet impact is proportional to sensible heat which heats up the droplets to the saturation temperature. In addition, to take account of the contribution of th heat flux upon impact of rebound droplets, it was assumed that the rebound droplets are distributed following the Gaussian distribution from 0 to L, which distance L is determined by maximum flight distance $L_{max}$. Also the calculated results were compared with existing experimental results.

• Journal of ILASS-Korea
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• v.3 no.3
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• pp.49-59
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• 1998

The vaporization characteristics and spray combustion processes in the high-pressure environment are numerically investigated. This study employ the high-pressure vaporization model together with the state-of-art spray submodels. The present high-pressure vaporization model can account for transient liquid heating, circulation effect inside the droplet forced convection, Stefan flow effect, real gas effect and ambient gas solubility in the liquid droplets. Computations are carried out for the evaporating sprays, the evaporating and burning sprays, and the spray combustion processes of the turbocharged diesel engine. Numerical results indicate that the high-pressure effects are quite crucial for simulating the spray combustion processes including vaporization, spray dynamics, combustion, and pollutant formation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.2 s.233
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• pp.287-293
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• 2005

In the present study, to determine the flow rate of droplets supplied to heat transfer surface after (j-1)th rebound, $D_X[j{\ge}2]^{\ast}$, it was assumed that the rebound droplets are distributed according to the Gaussian distribution from 0 to L, in which the flight distance L is determined by maximum flight distance $L_{max}$. We also assumed that $L_{max}$ is dependent on the air flow velocity and mean size of droplets. The local heat flux of a dilute spray in high temperature region was predicted using the newly evaluated $D_X[j{\ge}2]^{\ast}$. In addition, the predicted results by the present model were compared with the existing experimental data.

• Journal of computational fluids engineering
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• v.5 no.1
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• pp.8-13
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• 2000

In this study, the spray models incorporated into the GTT code were tested for sprays injected in quiescent swirling gases and for the sprays impinging on a flat wall, and the validity of the models has been confirmed by comparing the calculated results with the experimental data. Using this code, the gas flow, spray behavior and fuel vapor distributions in the combustion chamber of a D.I engine have been numerically analyzed with respect to the constant injection pressure and the injection pressure varying with injection time.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.3
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• pp.320-330
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• 1999

A numerical study was performed to investigate spray behavior and its interaction with air flow in a flame holding region of an oil burner(0.1MW) using the KIVA3 code. The numerical results in shape of the recirculating flow and size of the recirculation zone under different conditions were compared to those experimental results. The numerical results in fuel droplet trajectory show that a droplet under 30${\mu}m$ can follow the air flow but a droplet over 50${\mu}m$ penetrates the recirculation zone due to large momentum and a droplet of 30-50${\mu}m$ can follow the recirculating flow or pene-trates the recirculation zone.