• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.255-255
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• 2011

Zinc oxide based thin films have been extensively studied in recent several years because they have very interesting properties and zinc oxide is non-poisonous, abundant and cheap material. ZnO films are employed in different applications like transparent conductive layers in solar cells, protective coatings and so on. Wide industrial application of the ZnO films requires of development of cheap, effective and scalable technology. Typically used technologies don't completely satisfy the industrial requirements. In the present work, we studied effect of the deposition parameters on the structure and properties of ZnO films deposited by DC arc plasmatron. The varied parameters were gas flow rates, precursor composition, substrate temperature and post-deposition annealing temperature. Vapor of Zinc acetylacetone was used as source materials, oxygen was used as working gas and argon was used as the cathode protective gas and a transport gas for the vapor. The plasmatron power was varied in the range of 700-1500 watts. Flow rate of the gases and substrate temperature rate were varied in the wide range to optimize the properties of the deposited coatings. After deposition films were annealed in the hydrogen atmosphere in the wide range of temperatures. Structure of coatings was investigated using XRD and SEM. Chemical composition was analyzed using x-ray photoelectron spectroscopy. Sheet conductivity was measured by 4-point probe method. Optical properties of the transparent ZnO-based coatings were studied by the spectroscopy. It was shown that deposition by a DC Arc plasmatron can be used for low-cost production of zinc oxide films with good optical and electrical properties. Increasing of the oxygen content in the gas mixture during deposition allow to obtain high-resistive protective and insulation coatings with high adhesion to the metallic surface.

• Advances in environmental research
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• v.4 no.3
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• pp.183-196
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• 2015

Migration of leachate generated through embankment of construction waste soil (CWS) in low-lying areas was studied through physical and chemical analysis. A leachate solution containing soluble cations from CWS was found to have a pH above 9.0. To determine the distribution coefficients in the alkali solution, column and migration tests were conducted in the laboratory. The physical and chemical properties of CWS satisfied environmental soil criteria; however, the pH was high. The effective diffusion coefficients for CWS ions fell within the range of $0.725-3.3{\times}10^{-6}cm^2/s$. Properties of pore water and the amount of undissolved gas in pore water influenced advection-diffusion behavior. Contaminants migrating from CWS exhibited time-dependent concentration profiles and an advective component of transport. Thus, the transport equations for CWS contaminant concentrations satisfied the differential equations in accordance with Fick's 2nd law. Therefore, the migration of the contaminant plume when the landfilling CWS reaches water table can be predicted based on pH using the effective diffusion coefficient determined in a laboratory test.

• Membrane Journal
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• v.24 no.5
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• pp.409-415
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• 2014

This study is aimed to separate propylene and propane using membrane process instead of NCC(Naphtha Cracking Center) $C_3$ splitter. Membrane process is a low energy consumption and eco-friendly process while $C_3$ splitter requires high energy consumption in petrochemical processes. In this study, high performance facilitated transport membrane (FTM) is used for propylene/propane separation. FTM module was prepared on top of porous polyetherimide hollow fiber using PVP/$AgBF_4$/TCNQ. We developed simulation program predicting the membrane separation properties under operation conditions. Separation properties of FTM module for propylene and propane were obtained from the simulation program based on the pure gas permeation data. Based on these results, it is predicted that an one-stage membrane process provides 99.5% of propylene at permeate side from a binary gas mixture of 95/5 vol% $C_3H_6$ / vol% $C_3H_8$ supplied as a feed gas.

• Membrane Journal
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• v.25 no.3
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• pp.248-255
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• 2015

Aminated polyetherimide membrane synthesized in the laboratory according to amine ratio was used for measurement of gas permeability, diffusivity, and solubility about carbon dioxide, nitrogen, methane, oxygen, and sulfur dioxide with Time-lag method at room temperature. Generally, gas permeability is totally decreased because the more amination rate reacted to the main chain of amine groups, the more intermolecular space became narrow. However, gas permeability of sulfur dioxide was increased due to combination of sulfur dioxide and amine groups have acid and base properties respectively. Diffusivity and solubility of dry gas are totally decreased excluding sulfur dioxide as increasing amination rate. In case of sulfur dioxide, however, diffusivity as well as solubility was increased as increasing amination rate. Selectivity of carbon dioxide/nitrogen showed 60 when amination rate was 3. In case of humid gas, gas permeability of carbon dioxide was 70 barrer when relative humidity showed 100, and selectivity with nitrogen approximately showed 18.

• Particle and aerosol research
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• v.14 no.2
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• pp.41-47
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• 2018

Numerical analysis was conducted to characterize particle deposition onto a heated horizontal semiconductor wafer in vacuum environment. In order to calculate the properties of gas surrounding the wafer, the gas was assumed to obey the ideal gas law. Particle transport mechanisms considered in the present study were convection, Brownian diffusion, gravitational settling and thermophoresis. Averaged particle deposition velocities on the upper surface of the wafer were calculated with respect to particle size, based on the numerical results from the particle concentration equation in the Eulerian frame of reference. The deposition velocities were obtained for system pressures of 1000 Pa~1 atm, wafer heating of 0~5 K and particle sizes of $2{\sim}10^4nm$. The present numerical results showed good agreement with the available experimental ones.

• Journal of The Korean Astronomical Society
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• v.9 no.1
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• pp.1-6
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• 1976

The translational and reactive parts of thermal conductivity of a partially ionized solar magneto-plasma gas have been calculated based on Yun and Wyller's formulation (1972) along with Devoto's theory(1968). The computed results are presented as functions of temperature and pressure for given magnetic field strengths. The results of the calculations show that for most photospheric conditions the magnetic field does not play any important role in characterizing thermal properties of the ionized gas. However, when the gas pressure is low(e.g., P<10 dynes/$cm^2)$) the field becomes extremely effective even if its strength is quite small (e.g., B<0.1 gauss). The reactive part of the thermal transport is found to be very important when the gas is undertaking active ionization.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.3
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• pp.125-132
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• 2010

For typical governing dimensionless parameters of Ar = 5, Pr = 1.16, Le = 0.14, Pe = 3.57, Cv = 1.02, $Gr_s=2.65{\times}10^6$, the effects of thermo physical properties such as a molecular weight, a binary diffusivity coefficient, a partial pressure of component B on solutally buoyancy-driven convection (solutal Grashof number $Gr_s=2.65{\times}10^6$) are theoretically investigated for further understanding and insight into an essence of solutal convection occurring in the vapor phase during the physical vapor transport of a $Hg_2Cl_2-N_2$ system. The solutally buoyancy-driven convection is significantly affected by any significant disparity in the molecular weight of the crystal components and the impurity gas of nitrogen. The solutal convection in a vertical orientation is found to be more suppressed than a tenth reduction of gravitational accelerations in a horizontal orientation. For crystal growth parameters under consideration, the greater uniformity in the growth rate is obtained for either solutal convection mode in a vertical orientation or thermal convection mode in horizontal geometry. The growth rate is also found to be first order exponentially decayed for $10{\leq}P_B{\leq}200$ Torr.

• Proceedings of the KWS Conference
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• v.43
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• pp.183-184
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• 2004

High capacity container carrier has been considered for many decades to transport the more containers at the same time. Therefore, it is required for high capacity container ship to be applied thicker plate to accomodate a number of containers compared to that of general container ship. To maintain the same productivity of this thicker plate, new welding process should be considered. One of the process for vertical-up position is 2 electrodes EGW(Electro Gas Welding). 2 ectrodes EGW was applied and evaluated whether it can be applicable or not. The heat input used for 72mm thick plate was 520k11cm. from the mechanical test, it is considered that this process can be applicable, showing satisfaction of mechanical properties such as tensile strength, elongation and impact property.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.9-12
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• 2007

The transport mechanisms of the MTES (methyltriethoxysilane) templating silica/a-alumina composite membrane were evaluated by using four binary and one quaternary hydrogen mixtures through permeation experiments at unsteady- and steady-states. Since the permeation flux in the MTES membrane, through the experimental and theoretical studies, was affected by molecular sieving effects as well as surface diffusion properties, the kinetic and equilibrium separation should be considered simultaneously according to molecular properties. In order to depict the transient multi-component permeation on the templating silica membrane, the GMS (generalized Maxwell-Stefan) and DGM (dust gas model) were adapted to unsteady-state material balance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.11
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• pp.1595-1603
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• 2003

Droplet combustion at high ambient pressures is studied numerically by formulating one dimensional combustion model in the mixture of n-heptane fuel and air. The ambient pressure is supercritical conditions. The modified Soave-Redlich-Kwong state equation is used in the evaluation of thermophysical properties to account for the real gas effect on fluid p-v-T properties in high pressure conditions. Non-ideal thermodynamic and transport property at near critical and supercritical conditions are also considered. Several parametric studies are performed by changing ambient pressure and initial droplet diameter. Droplet lifetime decreased with increasing pressure. Surface temperature increased with increasing pressure. Ignition time increased with increasing initial droplet diameter. Temporal or spatial distribution of mass fraction, mass diffusivity, Lewis number, thermal conductivity, and specific heat were presented.