• Textile Coloration and Finishing
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• v.21 no.6
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• pp.56-63
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• 2009

In this study we have evaluated the separation characteristics and concentration of sericin using tubular type ultrafiltration membrane in silk degumming solution that extracted from electrolytic reduction water process. Ultrafiltration membranes have used in sericin separation performance and the separation characteristics of membrane satisfied typical Hagen-Poiseuille equation. It had the increase of flux according to the increase of feed pressure and temperature in occasion of pure water flux. And also the flux and solute rejection had about $25{\sim}60{\ell}/m^2{\cdot}h$ and more than 95% in sericin feed solution with concentration 1.00~1.89% at feed pressure force of $3{\sim}8kgf/cm^2$ respectively. In addition, the separation performance of tubular type ultrafiltration membrane for silk degumming solution was very steady-state with long experiment time.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1655-1659
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• 2008

Using numerical models, we investigated the efficiency of toxin removal using pulsatile flow in blood purification systems that use semipermeable membranes. The model consisted of a three-compartmental mass transfer model for the inside body and a solute kinetics model for the dialyzer. The model predicted the toxin concentration inside the body during blood purification therapy, and the toxin removal efficiencies at different flow configurations were compared quantitatively. According to the simulation results, the clearances of urea and ${\beta}_2$ microglobulin (B2M) using a pulsatile pump were improved by up to 30.9% for hemofiltration, with a 2.0% higher urea clearance and 4.6% higher B2M clearance for high flux dialysis, and a 3.9% higher urea clearance and 8.2% higher B2M clearance for hemodiafiltration. These results suggest that using a pulsatile blood pump in blood purification systems with a semipermeable membrane improves the efficacy of toxin removal, especially for large molecules and hemofiltration treatment.

• Membrane Journal
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• v.13 no.1
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• pp.29-36
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• 2003

A characterization of the permeation and separation using single salt solution was carried out with charged composite membranes. Various charged composite membranes were fabricated by blending an ionic polymer with a nonionic polymer in different ratios. In this study, sodium alginate, chitosan and poly(vinyl alcohol) were employed as anionic, cationic and nonionic polymers, respectively. The permeation and separation behaviors of the aqueous salt solutions have been investigated through the charged composite membranes with various charge densities. As the content of the ionic polymer increased in the membrane, the hydrophilicity of the membrane increased, and pure water flux and the solution flux increased correspondingly, indicating that the permeation performance through the membrane is determined mainly by its hydrophilicity. Electrostatic interaction between the charged membrane and ionic solute molecules, that is, Donnan exclusion, was observed to be attributed to salt rejection to a greater extent, and molecular sieve mechanism was effective for the separation of salts under a similar electrostatic circumstance of solutes.

• Textile Coloration and Finishing
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• v.17 no.3 s.82
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• pp.34-42
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• 2005

In this work, a practical separation performance was investigated on aqueous alcohol solutions, especially for iso-propyl alcohol (IPA), which is usually used during the semi- conductor rinsing process. The removal of various substances from waste aqueous IPA solutions was carried out by microfiltration with $0.1\~1{\mu}$m pore size of mean diameter as a pre-filter. Permeability and molecular weight cut-off of the functional polysulfone(PSf) ultrafiltration membrane to purify waste aqueous IPA solutions were measured through the ultrafiltration test. The solute rejection of PSf membrane had $92\%$ in 1,000ppm aqueous PEG solution with PEG molecular weight 10,000, the molecular weight cut-off had 10,000. The IPA concentration on the $CMPA-K^+$ membrane performance using pervaporation module system could be increased from $95.04 wt\%$ to more than $98.50wt\%$ in about 9hr at operation temperature of $70^{\circ}C$ using the pervaporation module system.

• Journal of Korea Soil Environment Society
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• v.1 no.2
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• pp.73-81
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• 1996

The self-diffusion coefficients of chloride and tritiated water ranged from 4.8 $\times$ 10-7 to 7.2 $\times$ 10-7 cm2/sec and 5.5 $\times$ 10-5 to 1.6 $\times$ 10-4 cm2/sec for three different depths of soil constituents at about 50% water content by volume, respectively Mobility of solute and water was conducted under steady-state flow conditions in a field soil consisting of 70 cm of clay to silty clay over a medium sand. A steady-state water flow conditions was maintained by applying irrigation water at a constant flux of 2cm per day. The water labeled with chloride and tritium was leached into the plot during the steady-state condition for 87 days. The positions of tritium and chloride as a function of soil depth and the time was measured by extracting samples of the soil solution with suction probes. Extremes in solute displacement occurred at equal and different depths within the plot. An analysis of these measurements indicated the observations of the pore-water velocity and the apparent diffusion coefficient were log normally disturbed. Twenty-four soil suction probes, used to identify the rate at which a solute was displaced in the soil, will yield an estimate of the mean pore-water velocity of this soils within a range of approximately 5% of its true value providing the effects of potential solute-soil interaction are taken into account.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.5.1-5.1
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• 2010

One of the most important environmental problems is global warming. Global warming is caused by increase in the amounts of water vapor, methane, carbon dioxide and other gases being released into the atmosphere as a result of the burning of fossil fuels. It has thus become important to reduce fossil fuel use. Environmentally friendly preparation of functional materials has, therefore, attracted much interest for environmental problems. Furthermore, nature mimetic processes are recently been of great interest as environmentally friendly one. There have been many studies on fabrication of various functional nanocrystals. Among various nanocrystal fabrication techniques, flux growth is an environmentally friendly, very convenient process and can produce functional nanocrystals at temperatures below the melting points of the solutes. Furthermore, this technique is suitable for the synthesis of crystals having an enhedral habit. In flux growth, the constituents of the materials to be crystallized are dissolved in a suitable flux (solvent) and crystal growth occurs as the solution becomes critically supersaturated. The supersaturation is attained by cooling the solution, by evaporation of the solvent or by a transport process in which the solute is made to flow from a hotter to a cooler region. Many kinds of oxide nanocrystals have been grown in our laboratory. For example, zero- (e.g., particle), one- (e.g., whisker and tube) and two-dimensional (e.g., sheet) nanocrystals were successfully grown by flux method. Our flux-growth technique has some industrial and ecological merits because the nanocrystal fabrication temperatures are far below their melting points and because the used reagents are less harmless to human being and the environment.

• Membrane Journal
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• v.7 no.2
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• pp.75-83
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• 1997

The disc plate and frame type modules for reverse osmosis were developed using three different types of baffles: linear (Type 1), curved (Type 2) and parallel shapes (Type 3). Separation performance tests were carried out for the modules using NaCl and sucrose solutions under the various concentrations and operating pressures. The permeation flux and solute rejection ratio for Type 3 module were the highest within operating pressure (35bar) and flow rate (6 l/min). The flux improvement ratio of Type 2 or 3 to Type 1 for NaCl solution decreased as operating pressure increased: flux improvement ratios of Type 3 for 1wt% of NaCl solution were about 100 and 10% at 10 and 35bar, respectively. However, the flux improvement ratio for sucrose solutions varied with the operating pressure and concentration. The permeation flux for Type 3 depended on the flow rate linearly, which is higher than that of turbulent flow region in the smooth channel.

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.122-131
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• 2019

In order to reuse and concentrate the sewage, a forward osmosis using fertilizer as draw solution was applied. Sewage-1, which is the supernatant after settling for 30 minutes for the primary settling basin influent, and Sewage-2, which is the supernatant after settling for 30 minutes for the effluent, and Sewage-3, which is the filtrate filtered through a $1{\mu}m$ cartridge filter for the effluent were tested. Eight draw solutions of $NH_4H_2PO_4$, KCl, $KNO_3$, $NH_4Cl$, $(NH_4)_2HPO_4$, $NH_4NO_3$, $NH_4HCO_3$, and $KHCO_3$ were used in consideration of osmotic pressure, solubility and pH. In the case of Sewage-3, the permeate flux was almost similar to that of the discharge water of the sewage treatment plant, and was larger than that of Sewage-1 and Sewage-2. $NH_4H_2PO_4$ was the smallest, and $NH_4NO_3$ was the largest in the specific reverse solute flux. $NH_4H_2PO_4$ was found to be most useful for the reuse and concentration of sewage because it contains nitrogen and phosphorus, which are the major components of fertilizer, as well as low specific reverse solute flux. When $NH_4H_2PO_4$ was used as the draw solution, the concentration factor after 24 hours for Sewage-3 was 1.72.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.703-710
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• 2011

As the spacer in the membrane module provide the channel space to flow the feed solution smoothly and induce the flow turbulence, it could help to reduce both the concentration polarization and to take the long-term operation of membrane modules with high permeate flux by mixing the accumulated contaminants on the membrane surface into the bulk solution. In this study, the concentration distribution in membrane module with respect to the spacers which have the cross-sectional shapes of circle, cross, diamond and hexagon, the angles of spacer configuration, solute rejection and permeate flux were interpreted and optimized numerically using the "COMSOL Multiphysics" software. The concentration on the membrane surface was kept the lowest level for the cross-shape among the above four types of spacers. Also the 30 degree spacer configuration was showed as the most efficient case. The concentrations on the membrane surface at the module outlet for without spacer and the cross shape with the 30 degree spacer configuration were 2.09 and 1.29 times higher than those at inlet, respectively. The reduction effect of concentration polarization increased rapidly as the permeate flux increased.

• Membrane and Water Treatment
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• v.3 no.3
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• pp.151-168
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• 2012

Gas sparging is one of the techniques used to control the concentration polarization during ultrafiltration. In this work, the effects of gas sparging in stratified flow regime were investigated during gel layer controlling cross flow ultrafiltration in a rectangular channel. Synthetic solution of pectin was used as the gel forming solute. The liquid and gas flow rates were selected such that a stratified flow regime was prevalent in the channel. A mass transfer model was developed for this system to quantify the effects of gas flow rates on mass transfer coefficient (Sherwood number). The results were compared with the case of no gas sparging. Gas sparging led to an increase of mass transfer coefficient by about 23% in this case. The limitation of the developed model was also evaluated and it was observed that beyond a gas flow rate of 20 l/h, the model was unable to explain the experimental observation, i.e., the decrease in permeate flux with flow rate.