• 한국결정성장학회지
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• 제8권2호
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• pp.227-232
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• 1998

Si, Mo 등을 substrate로 하고 Hot-Filament C.V.D법으로 저압으로 다이아몬드 박막을 생성시킬 때 탄화수소의 부착과정, 핵생성 및 성장을 조사하였다. 특성은 substrate의 종류, 온도, 압력, 유속 및 $CH_4-H_2$가스의 몰분율과 같은 process 변수로 조사하였으며 다이아몬드는 Ra-man spectroscopy로 측정하였다. 특히 다이아몬드 핵생성과 성장은 scratch와 같은 결함이 있는 곳에 발생하였고 표면확산 등이 핵생성 초기단계에서 중요한 역할을 하였다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.241-246
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• 1996

An analytical model to calculate rate of vapor generation due to heterogeneous wall nucleation in flashing flow is developed. In the present model, an important parameter of the vapor generation term, i.e. nucleation site density is calculated by integrating its probability distribution function with respect to active cavity radius. The limits of integration are minimum and maximum active cavity radii, and these are formulated using an active cavity model for nucleate boiling. This formulation, therefore. can statistically account for the effect of surface specific thermo-physical and geometric conditions on the vapor generation rate and flashing inception. For verifying the adequacy of the present model, steady state two-fluid and the bubble transport equations are solved with applicable constitutive equations. The applicable region of the bubble transport equation is also extended to churn-turbulent flow regime to predict interfacial area concentration at high void fraction. Predicted results in terms of axial pressure and void fraction profiles along the channels are compared with experimental data of Super Moby Dick and BNL Reasonable agreements have been achieved and this shows the applicability of the present model to flashing flow analysis.

• 한국전기전자재료학회논문지
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• 제11권7호
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• pp.552-556
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• 1998

Diamond thin films were deposited on Si substrate using $CH_4 and H_2$mixed gas by RF plasma CVD. Prior to deposition, the substrate surface was mechanically scratched with the diamond paste of $3{\mu}m$ to improve the density of nucleation sites. The microstructure of diamond films deposited with methane(0.5%~2%) at the reaction pressure ranging from 20 torr to 50torrr were studied by a scanning electron microscope. It was observed in the deposited diamond films that the nucleation density decreased and crystallinity increased with decreasing the methane concentration. However, the nucleation density and crystallinity were decreased with decreasing the process pressure.

• 대한설비공학회지:설비저널
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• 제8권3호
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• pp.131-150
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• 1979

Recently only a few correlations between various factors due to the different grades of surface roughness for the nucleate pool boiling have been proposed. The main purpose of this work is to test the validity of these types of correlations between related factors to nucleate pool boiling phenomena. The boiling experiments using distilled water were carried out at the heat flux ranging from $7.4\times10^4\;to\;2.4\times10^5kcal/m^2h$ on the sintered porous metal surface with the cavity diameter of 10, n, 40, 70, $100{\mu}$, respectively, at the atmospheric pressure, To determine the bubble sizes, number of nucleation sites, delay and growth time, frequency of bubble emission and rising velocities of bubbles, the high speed motion picture technique was employed. In the correlation $f{\propto}D_b^n$, where f denotes frequency of bubble emission and $D_b$ departure diameter, n, the power factor of $D_b$, have been found to be from -2 to -10/3. The correlation C in the correlation between heat flux q and density of nucleation sites $\frac{N}{A}$, $q=C(\frac{N}{A})^n$, was appeared to be more crucial than the power factor n. The correlation of the heat flux q to the temperature difference ${\Delta}T$ and the density of nucleation sites$\frac{N}{A}$, was proposed to be $$q-460{\Delta}T^{\frac{5}{4}}=K{\Delta}T{\frac{5}{3}}(\frac{N}{A})^{\frac{2}{3}}$$. The values of heat transfer coefficient obtained in this experiments for the porous sintered metal surface appeared to be very high in comparison with the formerly obtained results for the other surfaces.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1541-1546
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• 2012

The early stages of bismuth (Bi) electrodeposition on glass carbon electrode from alkaline electrolyte were studied by cyclic voltammetry, chronoamperometry, scanning electron microscopy, atomic force microscopy and X-ray diffraction. The CV analysis showed that the electrodeposition of Bi was determined to be quasireversible process with diffusion controlled. The current transients for Bi electrodeposition were analyzed according to the Scharifker-Hills model and the Heerman-Tarallo model. It can be concluded that the nucleation and growth mechanism was carried out under a 3D instantaneous nucleation, which was confirmed by SEM analysis. The kinetic growth parameters were obtained through a nonlinear fitting. In addition, the Bi film obtaining at -0.86 V for 1 hour was of compact and uniform surface with good smoothness, small roughness and a very high purity. The Bi film were indexed to rhombohedral crystal structure with preferred orientation of (0 1 2) planes to growth.

• 한국표면공학회지
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• 제41권2호
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• pp.48-50
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• 2008

Solid phase crystallization (SPC) of amorphous silicon is usually conducted at around $600^{\circ}C$ since it is used in the application of flat panel display using thermally susceptible glass substrate. In this study we conducted SPC experiments at temperatures higher than $600^{\circ}C$ using silicon wafers. Crystallization rate becomes dramatically rapid at higher temperatures since SPC kinetics is controlled by nucleation with high value of activation energy. We report SPC kinetics of high temperatures compared to that of low temperatures.

• 한국재료학회지
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• 제2권1호
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• pp.19-26
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• 1992

$WF_6$와 $SiH_4$의 화학반옹으로부터 산화규소막 위에 텅스텐 핵이 형성되는 현상을 실험을 통해 관찰하였다. 핵이 생성되는 속도는 반응온도가 높고 운반기체의 유량이 적으며 반응기내의 압력이 높을수록 큰 것으로 나타났다. 또한 반응기체가 흘러가는 방향에서 아랫쪽으로 위치하는 표면에 핵이 생성되는 속도가 큰 것으로 나타났다. 산화막위에 생성된 텅스텐 핵의 형상과 파단면을 주사현미경으로 관찰하였으며 산화막위에 형성된 텅스텐 박막의 화학적 조성을 밝혀내었다.

• 한국재료학회지
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• 제5권2호
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• pp.197-202
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• 1995

저압 화학 기상증착법으로 제작한 비정질 실리콘의 표면 형태 및 결정 성장 과정을 증착조건과 열처리 조건의 변화에 따라 조사하였다. 비정질에서 결정으로 변화하는 전이온도인 570~$590^{\circ}C$에서 증착한 시편은 (311)조직의 거친 표면으로 성장하였다. 같은 증착 온도에서 두께가 두꺼울수록 다결정에서 비정질로 변화하였다. 증착하는 과정에서의 결정화는 기판에서부터 시작되지만, 진공상태를 그대로 유지하고 비정질 실리콘을 전이온도에서 열처리하면 표면 실리콘 원자가 이동하여 결정화하였다.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2003년도 High Temperature Superconductivity Vol.XIII
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• pp.71-71
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• 2003

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 추계학술논문요약집
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• pp.600-601
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• 2018