• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.96-103
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• 2000

In this study, evaporation heat transfer tests were conducted in flat aluminum multi-channel tubes using R-22. Two internal geometries were tested ; one with smooth inner surface and the other with micro-fins. Data are presented for the following range of variables ; vapor quality $(0.1{\sim}0.9)$, mass flux$(100{\sim}600kg/m^2s)$ and heat flux$(5{\sim}15kW/m^2)$. The micro-tin tube showed higher heat transfer coefficients compared with those of the smooth tube. Results showed that, for the smooth tube, the effects of mass flux, quality and heat flux were not prominent, and existing correlations overpredicted the data. For the micro-fin tube at low quality, the heat transfer coefficient increased as heat flux increased. However, the trend was reversed at high quality Kandlikar's correlation predicted the low mass flux data, and Shah's correlation predicted the high mass flux data. The heat transfer coefficient of the micro fin tube was approximately two times larger than that of the plain tube. New correlation was developed based on present data.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.36.2-36.2
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• 2010

A small amount of Na incorporated in $CuInSe_2$ (CIS) absorption layer has become widely accepted as a requirement for efficient polycrystalline CIS solar cells. However, there is ongoing argument on the role of sodium incorporated in the absorber. In this paper, CIS absorption layers have been deposited using the three-stage co-evaporation process on Mo coated non-Alkali glass substrates. The NaF was evaporated during the second-stage with various fluxes. This paper is focusing on differences of micro-structure and composition ratio of the absorber realized with different Na contents and the variation of electrical properties of the cells with the corresponding absorbers. The analytical results of x-ray diffraction (XRD) patterns, field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS) and current-voltage characteristics will be discussed to investigate the effect of NaF flux on the CIS absorber formation and its cell performance.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.754-758
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• 2002

In order to reach the high quality of organic thin films such as high mobility for device applications, it is strongly desirable to study the growth properties of pentacene film as a function of evaporation condition. Here, we report the structure and morphology of thermal evaporated pentacene thin film by AFM, SEM, and XRD as a function of the evaporation rate and substrate temperature. These results play a key role in determining the electric performance of organic thin film transistor devices.

• 한국분무공학회지
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• 제14권3호
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• pp.109-116
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• 2009

The purpose of this study is the experimental and numerical investigation on the DME spray characteristics in the combustion chamber according to the injection timing in a common-rail injection system. The visualization system consisted of the high speed camera with metal halide lamp was used for analyzing the spray characteristics such as spray development processes and the spray tip penetration in the free and in-cylinder spray under various ambient pressure. In order to observe the spray characteristics as a function of injection timing, the piston head shape of re-entrant type was created and the fuel injected into the chamber according to various distance between nozzle tip and piston wall in consideration of injection timing. Also, the spray and evaporation characteristics in the cylinder was calculated by using KlVA-3V code for simulating spray development process and spray tip penetration under real engine conditions. It was revealed that the high ambient pressure of 3 MPa was led to delay the spray development and evaporation of DME spray. In addition, injected sprays after BTDC 20 degrees entered the bowl region and the spray at the BTDC 30 degrees was divided into two regions. In the calculated results, the liquefied spray tip penetration and fuel evaporation were shorter and more increased as the injection timing was retarded, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.311-312
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• 2005

By using 45$^{\circ}$ obliqued evaporation method with electron beam system, uniformly vertical liquid crystal (LC) alignment was achieved. And a high pretilt angles of about 2.5$^{\circ}$ were measured. Also, it was verified that there are no variations of pretilt angle as a function of $SiO_x$ thin film thickness 20nm and 50nm. A good LC alignment states were observed at annealing temperature of 250$^{\circ}C$. The high pretilt angle and the good thermal stability of LC alignment by 45$^{\circ}$ obliqued electron beam evaporation method on the $SiO_x$ thin film can be achieved.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.149-150
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• 2006

We describe a novel method of scanning probe nanofabrication using a AFM(atomic force microscopy) tip with assistance of Femtosecond laser pulses to enhance fabrication capability. Illumination of the AFM tip with ultra-short light pulses induces a strong electric field between the tip and the metal surface, which allows removing metal atoms from the surface by means of field evaporation. Quantum simulation reveals that the field evaporation is triggered even en air when the induced electric field reaches the level of a few volts per angstrom, which is low enough to avoid unwanted thermal damages on most metal surfaces. For experimental validation, a Ti: sapphire Femtosecond pulse laser with 10 fs pulse duration at 800 nm center wavelength was used with a tip coated with gold to fabricate nanostructures on a thin film gold surface. Experimental results demonstrate that fine structures with critical dimensions less than ${\sim}10nm$ can be successfully made with precise control of the repetition rate of Femtosecond laser pulses.

• 한국진공학회지
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• 제2권1호
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• pp.73-77
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• 1993

Hot-wall evaporation technique으로 세라믹 기판 위에 CdS 박막을 성장하였다. 이 때 증발원과 기판의 온도는 각각 570, 40$0^{\circ}C$이고 두께는 3$mu extrm{m}$이었다. 공기 중에서 열처리하여 감도(${\gamma}$), 광전류와 암전류의 비(pc/dc), 최대허용소비전력(MAPD), spectral response 및 응답시간 등을 측정하였다. $550^{\circ}C$, 30분간 열처리한 경우 가장 좋은 광전도 특성을 얻었으며 ${\gamma}$=0.89, pc/cd~104, MAPD: 492mW, rise time이 100ms, decay time이 260ms이었다.

• 한국식품과학회지
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• 제23권5호
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• pp.605-609
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• 1991

과일쥬스의 농축공정 중 고려되어야 할 중요한 공학적 물성치로는 비점상승, 밀도, 점도 등이다. 이들 물성치는 식품성분에 따라 고유한 특성을 나타내며 고형분의 함량, 압력, 온도에 따라 변화한다. 따라서 본 논문에 있어서 비점상승에 영향을 미치는 고형분의 함량과 압력에 대한 비점상승을 측정하였고 이에 따른 예측 모델식을 수립 하였다. 비점 상승도는 조작압력 및 고형분 함량을 독립변수로 하여 추정된 몇 가지 함수식으로부터 SPSS 통계 package 중 regression program을 이용하여 단순 회귀시켜 R값이 가장 높은 모델식을 택하였다. 또한 밀도는 고형분 함량에 따라 점도는 온도와 고형분 한량에 따라 예측 모델식을 각각 수립하였다.

• 한국분말재료학회지
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• 제9권2호
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• pp.89-95
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• 2002

Spherical fine powders of tungsten oxide powders were prepared by the emulsion evaporation method. The characteristics of the powders prepared were examined by means of TGA, X-ray diffraction, SEM and image analysis. The emulsions were prepared by fast mixing of aqueous phase containing tugsten and the organic phase which composed of kerosene, surfactant, and paraffin oil. Precursors were made by evaporating the emulsionin the kerosene bath at $160^{\circ}C$, and then calcined at $650^{\circ}C$ in order to produce tungsten oxide powders. The average particle size of the tungsten oxide powders was $0.5\mutextrm{m}$ and their shapes were spherical at the both case of w/o and o/w type emulsions. As the HLB value of the surfactant increased and the concentration of tungsten ions decreased the mean particle siqe of tungsten oxide powders decreased whereas agglomerationsize increased. The optimum concentration of Span 80 was 8 percent by volume, and the optimum stirring speed in the emulsion formation was 5000 rpm in order to obtain fine and well dispersed $WO_3$ powders.

• 한국분말재료학회지
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• 제20권6호
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• pp.411-424
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• 2013

In this study, the synthesis of nickel nanoparticles and copper nanospheres for the potential applications of MLCC electrode materials has been studied by plasma arc evaporation method. The change in the broad distribution of the size of nickel and copper nanopowders is successfully controlled by manifesting proper mixture of gas ambiance for plasma generation in the size range of 20 to 200 nm in diameter. The factors affecting the mean diameter of the nanopowder was studied by changing the composition of reactive gases, indicating that nitrogen enhances the formation of larger particles compared to hydrogen gas. The morphologies and particle sizes of the metal nanoparticles were observed by SEM, and ultrathin oxide layers on the powder surface generated during passivation step have been confirmed using TEM. The metallic FCC structure of the nanoparticles was confirmed using powder X-ray diffraction method.