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박현채;김은영
- Proceedings of the Membrane Society of Korea Conference
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- 1995.04a
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- pp.34-35
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- 1995
The unique feature of pervaporation is the mass transfer from a liquid phase to a vapor phase through a non-porous polymeric membrane. When a liquid mixture is brought into contact with a membrane at one side, it is sorbed into the membrane. Due to a driving force applied across the membrane, the sotbed liquid molecules permeate through the membrane and evaporate at the downstream side of the membrane. In pervaporation the permeated species are usually removed from the downstream side under a relatively low vapor pressure, for example by evacuation with a vacuum pump. As far as this condition is fulfilled, the evaporation step can be considered to be much faster than sorption or diffusion. Hence evaporation does not contribute to permselectivity. Therefore the separation by pervaporation results from the differences in the preferential sorption of the individual components of a mixture into the membrane together with the diffusion rates through the membrane. This postulation implies that both sorption and diffusion phenomena have to be accounted for to understand the physico-chemical nature of the pervaporation separation process.
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Schwambera, M.;Meyer, N.;Keiper, D.;Heuken, M.;Hartmann, S.;Kowalsky, W.;Farahzadi, A.;Niyamakom, P.;Beigmohamadi, M.;Wuttig, M.
- 한국정보디스플레이학회:학술대회논문집
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- 2007.08a
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- pp.336-339
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- 2007
The enhanced control of OLED deposition processes by Organic Vapor Phase Deposition $(OVPD^{(R)})$ is discussed. $OVPD^{(R)}$ opens a wide space of process control parameters. It allows the accurate and individual control of deposition layer properties like morphology and precise mixing of multi component layers (co-deposition) in comparison to conventional deposition manufacturing processes like e. g. VTE (vacuum thermal evaporation).
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김선태;문동찬
- Journal of the Korean Institute of Electrical and Electronic Material Engineers
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- v.11 no.10
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- pp.784-789
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- 1998
In this work, the optical properties of freestanding GaN single crystalline substrate grown by hydride vapor phase epitaxy(HVPE) were investigated. The low temperature PL spectrum in freestanding GaN consists of free and bound exciton emissions, and a deep DAP recombination around at 1.8eV. The optically-pumped stimulated emission in freestanding GaN substrate was observed at room temperature. At the maximum power density of 2MW/$\textrm{cm}^2$, the peak energy and FEHM of stimulated emission were 3.318 eV and 8meV, respectively. The excitation power dependence on the integrated emission intensity indicates the threshold pumping power density of 0.4 MW/$\textrm{cm}^2$.
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Park, Kwan-Dong;Won, Ji-Hye;Ha, Ji-Hyun
- Proceedings of the Korean Institute of Navigation and Port Research Conference
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- v.2
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- pp.41-45
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- 2006
To get accurate positions of GPS antennas, one should apply phase center variations (PCV) corrections in the data processing. Until recently, relative calibrations, originally proposed by National Geodetic Survey of United States, were the international standard. However, in late 2006, International GNSS Service will switch to absolute calibration methods. In this study, we compared the position differences caused by different PCV models, and their effects on the calculations of Precipitable Water Vapor (PWV) in the atmosphere. Data from ${\sim}40$ permanent GPS stations in Korea were processed and we found that the vertical position differences reach up to 5 cm, depending on the model selected. Also the PWV values varied quite significantly: the maximum bias in the computed PWV values was ${\sim}4$ mm.
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Lee, Soo-Keun
- KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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- v.9 no.1
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- pp.11-18
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- 2003
The pure $TiO_2$ particles have been prepared in vapor-phase hydrolysis of titanium tetraisopropoxide(TTIP). The rate of TTIP hydrolysis was so fast that the overall rate of formation of $TiO_2$ was controlled by the rate of mixing of TTIP and $H_2O$. Thus, the primary $TiO_2$ particles were prepared in nano sizes to form chainlike aggregates due to rapid coagulation. The pure $TiO_2$ particles as prepared were amorphous at the reactor set temperatures below $400^{\circ}C$ and became anatase at the temperatures of $450^{\circ}C$ above while the weak rutile peaks were also observed above $800^{\circ}C$. The actual size of primary particles as prepared were reduced by increasing the reactor set temperature while their crystalline sizes as well as BET sizes increased by post-sintering.
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