• Journal of the Microelectronics and Packaging Society
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• v.25 no.1
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• pp.11-15
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• 2018

In this study, we deposited silver nanoparticles on the nanocone array structure which was fabricated by the UV nanoimprint process for optical signal amplification. The deposition of the silver nanoparticles was based on the evaporation behavior of the solution droplet according to wettability of surface and the deposition pattern changed from the center of the droplet to the edge depending on the difference of thermal energy. The optical property of silver nanoparticles that were deposited on imprinted nanohole patterns was simulated by the Finite difference time domain (FDTD) analysis method, and it was confirmed that energy was concentrated around the silver nanoparticle of the finally fabricated structure.

• Korean Chemical Engineering Research
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• v.44 no.3
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• pp.235-242
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• 2006

Spray pyrosysis is a process to prepare particles and films by evaporating and decomposing droplets of precursor solutions in the order of 1-10 micrometer in diameter. Key elements of the spray pyrolysis process include precursor, solvent, droplet generator, and reactor. Various combination of these 4 elements produces wide range of particles and films. In general. the current status of the spray pyrolysis technology is not quite promising for commercial success. However, this process will be feasible to produce multicomponent functional materials of controlled morphology. In this paper, current status of the spray pyrolysis technology is introduced with the emphasis of production of fluorescence particles.

• Journal of the Korean Society for Heat Treatment
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• v.19 no.3
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• pp.141-148
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• 2006

An experimental study is presented for water droplet impingement on a steel surface in the process of heat treatment. The objective of the present work is to examine characteristic of evaporation cooling due to surface roughness and droplet diameter under conductive heat input condition. The surface temperatures varied from $80{\sim}155^{\circ}C$, surface roughness was from $R_a=0.12{\mu}m$ to $R_a=1.14{\mu}m$ and droplet diameter was from 2.4 mm to 3.0 mm. The results show that the total evaporation time is shorter for the larger surface roughness and the smaller droplet size, the time average heat flux has maximum value for the larger surface roughness and the smaller droplet size. The total evaporation time has not influence on the nuclear boiling region.

• Journal of the Korean Society for Heat Treatment
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• v.18 no.6
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• pp.375-382
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• 2005

This paper presents the results of experimental investigation for the effect of heat conduction on the evaporation cooling of water droplet in the process of heat treatment. The experiments are mainly focused on the surface temperature, the surface roughness and the droplet diameter at aluminum. The range of surface temperature is from $80^{\circ}C$ to $140^{\circ}C$, surface roughness is from $R_a=0.18{\mu}m$ to $R_a=1.36{\mu}m$ and droplet diameter is from 2.4 mm to 3.0 mm. The results show that the total evaporation time is shorter for the larger surface roughness, the time averaged heat flux has maximum value for the larger surface roughness and exist the critical heat flux. The total evaporation time has a big influence on the evaporation region for the smaller droplet size, but the total evaporation time has not influence on the nuclear boiling region.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.4
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• pp.10-16
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• 1983

액체의 미립화는 기계산업분야 뿐만 아니라, 농약살포, 화학 공학의 분무건조, 반응의 촉진, 분 체제조, 식품공업 등 폭넓게 이용되며 또한 각분야에서 그 필요성이 강조되고 있다. 특히 기계 산업분야에서는 액체연료의 분무연소(boiler, gas turbine, 자동차용engine등) 원자로 노심의 spray cooling, spray drying, spray painting 등 그 이용도는 날로 증가되는 추세에 있다. 액체를 미 립화하는 이유는 각각의 분야나 사용하는 목적에 따라 다르지만, 대별하면 다음과 같다. (1) 액체의 단위 체적당 표면적을 증대시키기 위하여 (2) 직경이 작은 입자의 필요성 (3) 균일한 입경의 액적군을 얻기 위하여 등을 들 수 있다. 액체의 미립화에 대한 요구는 산업의 발당, 대기오염, 생energy 등의 문제가 중요시됨에 따라 다양화되고 있다. 따라서 응용면에서는 atomizer의 성능개선과 설계법, 새로운 미립화방법, 상업에의 분무이용기술, 분무계측법 등의 개발이 필요하게 된다. 액체미립화에서 취급하는 사항은 그 내용에 따라 다음과 같이 분류된다. (1) 액체의 미립화기구 : 기액계면의 불안정성과 분열기구에 관한 것으로, 액체형상으로써 액주, 액막 및 액적으로 나눌 수 있다. (2) 액체의 미립화 방법과 특성 : energy의 종유와 부가방식에 따랄 나누어진다. (3) 합체, 분산, 증발 등 분무의 운동이나 열적거동 (4) 분무입경이나 운동의 계측법과 특성도시 (5) 액체미립화의 각종응용 본보에서는 상기의 각 항목중, 특히 액체의 미립화방법과 분무특성에 대해서만 말하기로 한다.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.5
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• pp.130-141
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• 1996

Numerical study of a confined, swirling, isothermal and spray-combusting flows has been presented. The pressure-velocity coupling in the Eulerian gas-phase equation is handled by the improved PISO algorithm. The droplet dispersion by turbulence is introduced by a Stochastic Separated Flow(SSF) model. The k-$\varepsilon$ turbulence model and the eddy dissipation model are employed to account for turbulence-combustion interaction. The detailed comparison with experimental data has been made for the isothermal jet swirling flows and the nearly monodisperse spray-combusting flow in the swirl combustor.

• Journal of the Korean Society of Safety
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• v.19 no.2
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• pp.61-68
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• 2004

The evaporation phenomena of waterr droplet which has sodium acetate trihydrate($CH_3COONa{\cdot}3H_2O$) as a fire suppression additive were studied. Solutions of sodium salt up to 50% and heated stainless-steel surface were used in the experiment. The evaporation process was recorded using a charge-coupled-device camera at 120 frames per second. The average evaporation rate of the sodium acetate trihydrate soluation was lower than that of pure water at a given surface temperature and decreased with the concentration increase due to the precipitation of salt in the liquid film and change of surface tension. The variation of liquied film diameter was measured by time and it was increased by the hot surface temperature increase.

• Journal of the Korean Society of Combustion
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• v.8 no.2
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• pp.17-26
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• 2003

The objective of present study is to understand the interaction of burning droplets in air stream for various droplet arrangement. The unsteady combustion of linearly arranged droplets with a convective flow has been studied numerically. The droplets with spacing of $5R_0\;to\;40R_0$ horizontally and with spacing of $4R_0\;to\;16R_0$ vertically are studied. The effects of Reynolds number, horizontal spacing, and vertical spacing on the interaction of burning droplets are examined. The results indicate that the droplet burning behavior is influenced by Reynolds number and relative location of droplets in the array. The interaction of droplets is increased for arrays with smaller droplet spacing. The vaporization of droplets in the array is varied with both horizontal and vertical spacing exponentially.

• Journal of the Korean Society of Visualization
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• v.15 no.1
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• pp.25-31
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• 2017

This study aims to visualize the Marangoni flow inside a droplet placed on heated hydrophobic surface and to measure its internal velocity field. The experimental result shows that the internal velocity increases with the increase of the plate temperature. In addition, the temperature difference induces the initial flow and drives the Marangoni circulation inside the droplet as soon as the evaporation starts (i.e. the thermal Marangoni flow). The fluorescence particles in the droplet trace two large-scale counter-rotating vortex pairs yielding the downwards flow along the vertical central axis. These vortex pairs gradually become small and move towards the contact line as time goes by, and this Marangoni flow sustains only for a half of the total evaporation time.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.931-936
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• 2000

An experimental study has been carried out of the combustion behavior of single fuel droplets of water-in-light oil emulsions in an electric furnace to elucidate the dominant factor for the occurrence of micro-explosions. The tests were carried out by changing the following four parameters; the size of water droplets in the emulsified fuels having the same water content, the ratio of water to light oil, ambient temperature in electric furnace, and the kind of fuel having different viscosity(Kerosene, Olive Oil). The result shows that the each parameter plays the different role in the effect on behavior of vaporization, explosion, ignition and combustion for single droplets of water-in-oil Emulsified fuels.