• Journal of Advanced Marine Engineering and Technology
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• 제29권3호
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• pp.297-305
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• 2005

The evaporation heat transfer coefficient of $CO_2$ (R-744) in a horizontal tube was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver. a variable-speed pump. a mass flow meter. a pre-heater and evaporator (test section). The test section consists of a smooth. horizontal stainless steel tube of 7.75 mm inner diameter. The experiments were conducted at mass flux of 200 to $500\;kg/m^{2}s$. saturation temperature of $-5^{\circ}C\;to\;5^{\circ}C$. and heat flux of 10 to $40\;kW/m^2$. The test results showed the evaporation heat transfer of $CO_2$ has greatly effect on more nucleate boiling than convective boiling. The evaporation heat transfer coefficients of $CO_2$ are highly dependent on the vapor quality. heat flux and saturation temperature. The evaporation heat transfer coefficient of $CO_2$ is very larger than that of R-22 and R-134a. In making a comparison between test results and existing correlations. the present experimental data are the best fit for the correlation of Jung et al. But it was failed to predict the evaporation heat transfer coefficient of $CO_2$ using by the existing correlation. Therefore. it is necessary to develop reliable and accurate predictions determining the evaporation heat transfer coefficient of $CO_2$ in a horizontal tube.

• International Journal of Air-Conditioning and Refrigeration
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• 제13권4호
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• pp.167-174
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• 2005

The evaporation heat transfer coefficient of $CO_2$ (R-744) in a horizontal tube was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and evaporator (test section). The test section consists of a smooth horizontal stainless steel tube of 7.75 mm inner diameter. The experiments were conducted at mass flux of 200 to $500kg/m^2s$, saturation temperature of $-5^{\circ}C\;to\;5^{\circ}C$, and heat flux of 10 to $40kW/m^2$. The test results showed the evaporation heat transfer of $CO_2$ has greater effect on nucleate boiling than convective boiling. The evaporation heat transfer coefficient of $CO_2$ is highly dependent on the vapor quality, heat flux and saturation temperature. The evaporation heat transfer coefficient of $CO_2$ is very larger than that of R-22 and R-134a. In comparison with test results and existing correlations, the best fit of the present experimental data is obtained with the correlation of Jung et al. But the existing correlations failed to predict the evaporation heat transfer coefficient of $CO_2$. Therefore, it is necessary to develop reliable and accurate predictions determining the evaporation heat transfer coefficient of $CO_2$ in a horizontal tube.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.38.1-38.1
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• 2010

The trend to thinner crystalline silicon solar wafers in production of solar cells investigates re-evolution of back surface field (BSF) formation. We have studied mechanisms of back contact formation in Al evaporation and screen printed Al paste for Si solar cells by TEM analysis. We observed that Si diffuse into Al during heat up. The Si diffusion process made vacancies in Si wafer. The Al began to seep into the Si wafer (Al spike). During heat down, the Al spike were shrink which causes the doped region (BSF).

• 한국진공학회지
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• 제22권1호
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• pp.26-30
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• 2013

고유전율 절연체의 한 종류인 산화알루미늄 박막을 전자빔 증착법으로 형성하는 과정에서 산소 이온 빔의 조사를 이용, 산소 이온 빔 보조 증착 효과를 기대하였다. 산소 이온 보조 증착법으로 형성된 산화 알루미늄 박막의 두께 측정 결과, 높은 에너지에서의 이온 빔에 의한 식각 효과를 확인할 수 있었으며, 산소 이온 보조 증착 결과보다 높은 커패시턴스 값도 관찰할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.328-331
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• 2000

The effect of the constituent elements and their composition of the seed layer on the properties of the evaporated Zn thin films was investigated. It was carried out by the analysis of the preferred orientation and the grain size, and the corrosion characteristics. Seed layers were prepared by evaporation of Al and AlCu respectively, and here the Cu content as additives of the source materials of seed layers were designed 5 a/o to 20 a/o. The values of full width at half maximum (FWHM) of the (002) x-ray diffraction peaks of Zn decreased by increasing the amount of the additives on Al seed layer, as a results, the grain sizes also decreased. In order to characteristics of Zn thin films evaporated on the various seed layers, electrical resistivity changes with a function of time at the temperature of 40$^{\circ}C$ and the relative humidity of 80%, as a result, the relative resistivity changes were increased by decreasing the grain size and the FWHM values of (002) peaks of Zn.

• 멤브레인
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• 제31권1호
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• pp.80-85
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• 2021

본 논문에서는 ~1.5 ㎛의 기공 크기를 가지는 고투과도 알파 알루미나 지지체 위에 도포된 서스펜션의 증발유도 자기조립 현상을 이용하여 중간층을 형성하는 새로운 코팅 방식을 소개한다. 새로운 코팅 방법으로 만들어진 중간층은 일반적으로 사용되는 담지법으로 코팅된 중간층과 비교하여 표면거칠기와 불균일도가 낮아 코팅에 적합하였다. 복합막 지지체로서의 평가를 위해 제조된 지지체는 감마 알루미나 복합막 제조에 사용되었다. 메조 기공을 가지는 감마 알루미나 복합막은 반복코팅 없이도 매크로 기공 크기의 결함이 존재하지 않았으며 일반적으로 널리 사용되는 100~200 nm의 기공 크기를 가지는 지지체로부터 만들어진 같은 두께의 복합막과 비교하여 2.3배 이상의 높은 질소투과도를 보였다.

• 한국표면공학회지
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• 제40권5호
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• pp.241-244
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• 2007

$MgF_2$/Cr/$MgF_2$, $MgF_2$/Cu/$MgF_2$ and $MgF_2$/Al/$MgF_2$ multi-layered thin films were fabricated by evaporation system. $MgF_2$ and Cr(Cu, And Al) was selected as a low refractive index material and mid reflector layer, respectively. Optical properties including color effect were systematically studied in terms of different film layer by using spectrophotometer. Experimental results were compared to the simulation result. The films consistings of $MgF_2$/Cr/$MgF_2$, $MgF_2$/Cu/$MgF_2$, $MgF_2$/Al/$MgF_2$ multi-layered thin films showed wavelength range of $430{\sim}780nm$, typically color range between greenish yellow and orange at view angle of $45^{\circ}$. It was confirmed that this experimental result was well matched with simulation result.

• Transactions on Electrical and Electronic Materials
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• 제9권3호
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• pp.105-109
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• 2008

Electrical characteristics of organic light-emitting diodes were investigated by varying a hole-size in evaporation boat in the device structure of ITO/tris(8-hydroxyquinoline) aluminum$(Alq_3)$/Al. The device was manufactured using a thermal evaporation under a base pressure of $5{\times}10^{-6}$ Torr. The $Alq_3$ emitting organics were evaporated to be a thickness of 100 nm at a deposition rate of $1.5{\AA}/s$. A cylindrical-shaped evaporation boat was made out of stainless steel with a small size of hole on top of the boat. Several evaporation boats were made having a different hole size on top; 0.8 mm, 1.0 mm, 1.5 mm, and 3.0 mm. We found that when the hole size on top of the evaporation boat is 1.0 mm, the average roughness is rather smoother compared to the other ones. Also, luminance and external quantum efficiency are superior to the others. Compared to the ones from the devices made with the hole-size of 0.8 mm boat. The luminance and external quantum efficiency of the device made with the hole-size of 1.0 mm boat were improved by a factor of seventy and thirty three, respectively. Also operating voltage is reduced to 2 V.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.38.2-38.2
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• 2010

We have studied mechanisms of back contact formation in Al evaporation and screen printed Al paste for Si solar cells by TEM analysis. We observed that Si diffuse into Al during heat up. The Si diffusion process made vacancies in Si wafer. The Al began to seep into the Si wafer (Al spike). During heat down, the Al spike were shrink which causes the doped region (BSF).

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1994년도 추계학술대회 논문집
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• pp.106-108
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• 1994

Electromigration(EM) tests were carried out on Al and Cu films in HV systems to study surface migration. The Al films were made on oxidized silicon wafers by thermal evaporation, in-situ annealed at 300$^{\circ}C$, patterned, and EM tested at 260$^{\circ}C$ and 4.5MA/$\textrm{cm}^2$. SEM observation with back scattered electron mode on the EM tested Al films disclosed that thinning took place under the native Al oxide. In the case of Cu films, tested using in-situ TEM, thinning was also observed at the early stage of void formation even though the thinned areas were much less than those of the Al films.