• Membrane Journal
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• v.19 no.1
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• pp.72-82
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• 2009

A mathematical model was written for simulating the removal of phenol from wastewater in enzyme-loaded membrane reactor (EMR). The numerical simulation program was developed so as to predict the degradation of phenol through an EMR. Numerical model proves to be effective in searching for optimal operating conditions and creating an optimal microenvironment for the biocatalyst in order to optimize productivity. In this study, several dimensionless parameters such as Thiele Modulus (${\phi}^2$, dimensionless Michaelis-Menten constant ($\xi$), Peclet number (Pe) were introduced to simplify their effects on system efficiency. In particular, the study of phenol conversion at different feed compositions shows that low phenol concentrations and high Thiele Modulus values lead to higher reactant degradation.

• Korean Membrane Journal
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• v.8 no.1
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• pp.13-20
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• 2006

The production of CO-free hydrogen streams for feeding PEM-Fuel Cells using catalytic zeolite membrane reactors was analysed by means of selective oxidation. Tubular FAU (Na-Y) zeolite membranes, prepared by a secondary growth method and Pt-loaded, were used in a flow-through MR configuration. The catalytic tests were carried out at $200^{\circ}C$ and at different pressures with a simulated dry reformate shifted gas mixture ($H_2$ ca. 60%, CO 1 %, plus $O_2,\;N_2,\;CO_2$). The operative $O_2/CO$ stoichiometric equivalent feed ratio was ${\lambda}= 2$. These catalytic tests, reducing the CO concentration down to $10{\sim}50$ ppm, verified the possibility of MR integration after using a low temperature water-gas shift unit of a fuel processor to convert hydrocarbons into hydrogen-rich gas.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2005.07a
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• pp.34-34
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• 2005

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.924-927
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• 2003

Aluminium-doped ZnO (ZnO:Al) films were grown by atomic layer-controlled deposition on glass substrates at temperature of 200 $^{\circ}C$ using diethylzinc($Zn(C_{2}H_{2})_{2}$; DEtZn), water($H_{2}O$) and trimethylaluminium ($Al(CH_{3})_{3}$; TMA) as precursors. As the cycle ratio of TMA to DEZn(TMA/DEZn) increased, the resistivity of the films decreased and the roughness increased. In the case of TMA/DEZn pulse ratio of 1 to 10, the film had a resistivity of $9.7{\times}l0^{-4}{\Omega}{\cdot}cm$ and a roughness of 2.25nm(rms), while in the case of only DEZ injection the film had a resistivity of $3.5{\times}10^{-3}{\Omega}{\cdot}cm$ and a roughness of 1.07nm(rms)

• Korean Membrane Journal
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• v.5 no.1
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• pp.68-74
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• 2003

Methane steam reforming (MSR) reaction for hydrogen production was studied in a membrane reactor (MR) using two tubular membranes, one Pd-based and one of porous alumina. A higher methane conversion than the thermodynamic equilibrium for a traditional reactor (TR) was achieved using MRs. The experimental temperature range was 350-500$^{\circ}C$; no sweep-gas was employed during reaction tests to avoid its back-permeation through the membrane and the steam/methane molar feed ratio (m) varied in the range 3.5-5.9. The best results (the difference between the MR conversion and the thermodynamic equilibrium was of about 7%) were achieved with the alumina membrane, working with the highest steam/methane ratio and at 450$^{\circ}C$. Silica membranes prepared at KRICT laboratories were characterized with permeation tests on single gases (N$_2$, H$_2$ and CH$_4$). These membranes are suited for H$_2$ separation at high temperature.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.65-68
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• 2003

The paper discusses the use of stable emulsion, prepared by membrane emulsification technology, to improve the enantiocatalytic performance of immobilised lipase in multiphasic membrane reactors. The production of optical pure (S)-naproxen from racemic naproxen methyl ester has been used as model reaction system. The enzyme was immobilised in the sponge layer (shell side) of capillary polyamide membrane with 50 kDa cut-off, The O/W emulsion, containing the substrate in the organic dispersed phase, was fed to the enzyme membrane reactor from shell-to-lumen. The results evidenced that lipase maintained stable activity during all the operation time (more than 250 hours), showing an enantiomeric excess (96 $\pm$2%) comparable to the free enzyme (98 $\pm$ 1%) and much higher compared to similar lipase-loaded membrane reactors used in two-separate phase systems (90%). The study showed that immobilised enzymes can achieve high stability as well as high catalytic activity and enantioselectivity.

• Economic and Environmental Geology
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• v.45 no.2
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• pp.89-104
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• 2012

The solubility of aluminum for two Andisol profiles formed on pyroclastic materials and basaltic rocks from Jeju Island, Korea was investigated. It is found that high organic carbon content and $Al_{pyrophosphate}/Al_{oxalate}$ ratios in the A horizons, suggesting the substantial amounts of reactive Al are associated with organic matter, whereas the low organic carbon content and the $Al_{pyrophosphate}/Al_{oxalate}$ ratios in the Bo horizons indicate that a major part of the reactive Al should be bound inorganically. The differential FT-IR spectra following acid-oxalate dissolution and heating up to 150 and $350^{\circ}C$, and transmission electron microscope (TEM) observation confirm that imogolite is in the Bo horizon. Our results of equilibration experiments demonstrate that the Al solubility in the Bo horizon for Andisols can be clarified by the congruent dissolution model for imogolite-type material (ITM), rather than by the simultaneous equilibrium with both ITM and Al hydroxy-interlayered aluminosilicate. With results from dialysis and aging procedures, it is noted that the formation of a proto imogolite sol showing its transformation to imogolite, which supports the congruent dissolution of ITM primarily controlling the Al solubility of Andisols in Jeju Island, Korea.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.21-24
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• 2003

Methane steam reforming (MSR) was studied in a membrane reactor (MR) with a Pd-based and a porous alumina membranes. MRs showed methane conversion higher than that foresaw by the thermodynamic equilibrium for a traditional reactor (TR). Silica membranes prepared at KRICT were characterized with permeation tests on single gases ($N_2$, $H_2$ and $CH_4$). These silica membranes can be also used for high temperature applications such as $H_2$ separation $CO_2$ hydrogenation for methanol production is another reaction where $H_2O$ selective removal can be performed with these silica membranes.

• Journal of the Korean Regional Science Association
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• v.34 no.4
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• pp.61-74
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• 2018

This study aims to analyze the convergence change of smart city industries in Korea. Industries of Smart city can be defined ICTs and Knowledge embedded construction industry. The input output model and structural path analysis have been done using the input output tables published by Bank of Korea in 1980 and 2014. GDP deflator was applied to the input output tables. 403 industries were reclassified into 27 industries and 8 industries categories: Agriculture and Mining(AM), Non-IT Manufacture(NITM), IT Manufacture(ITM), Energy Supply(EnS), Construction as smart city(C), IT Service(ITS), Knowledge Service(KS), Etc. Service(EtS). The results are as follows; First, the input output coefficient analysis showed that The information and communication service industry(ITS) and the energy supply industry(EnS) have increased input to the construction industry(C). On the other hands, knowledge service industry(KS) and etc. service industries(EtS) decreased. Second, the multiplier analysis revealed that construction industry(C) led by smart city had a great influence on ITS, EnS, ITM and NITM directly and indirectly. Furthermore, The IT industry had the biggest change from 1980 to 2014. Third, the smart city industry has created a new convergence of 117, and it has been leading to segmentation of the structure. Change of convergence has been proceeding mainly in the ITS and EnS, NITM, ITM industries.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.45-49
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• 2001

We have investigated physical and electrical properties of the Hf $O_2$/HfS $i_{x}$/ $O_{y}$ thin film for alternative gate dielectrics in the metal-oxide-semiconductor device. The oxidation of Hf deposited directly on the Si substrate results in the H $f_{x}$/ $O_{y}$ interfacial layer and the high-k Hf $O_2$film simultaneously. Interestingly, the post-oxidation N2 annealing of the H102/H1Si70y thin films reduces(increases) the thickness of an amorphous HfS $i_{x}$/ $O_{y}$ layer(Hf $O_2$ layer). This phenomenon causes the increase of the effective dielectric constant, while maintaining the excellent interfacial properties. The hysteresis window in C-V curves and the midgap interface state density( $D_{itm}$) of Hf $O_2$/HfS $i_{x}$/ $O_{y}$ thin films less than 10 mV and ~3$\times$10$^{11}$ c $m^{-2}$ -eV without post-metallization annealing, respectively. The leakage current was also low (1$\times$10-s A/c $m^2$ at $V_{g}$ = +2 V). It is believed that these excellent results were obtained due to existence of the amorphous HfS $i_{x}$/ $O_{y}$ buffer layer. We also investigated the charge trapping characteristics using Fowler-Nordheim electron injection: We found that the degradation of Hf $O_2$/HfS $i_{x}$/ $O_{y}$ gate oxides is more severe when electrons were injected from the gate electrode.e electrode.e.e electrode.e.