• Journal of Environmental Science International
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• v.9 no.2
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• pp.159-164
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• 2000

For the purpose of development of a liquid membrane permeator which separates metal ions from aqueous solutions continuously and effectively, a continuous membrane permeator with the membrane solution trapped between extraction and stripping phases by two micro-porous hydrophilic films was manufactured. Experimental researches on the separation of zinc ion from aqueous solutions were performed in the liquid membrane permeator with 30 vol % D2EHPA solution in kerosine as liquid membrane. As results, the liquid membrane permeator separates zinc ion from aqueous solutions continuously and effectively in the wide range of operating conditions. A simple mass transfer rate model using equilibrium constant of the extraction reaction for the system used were proposed, and the model was compared with experimental results of separation of zinc ion in the permeator. And the effects of operating factors, such as space time, pH of extraction solution, extraction temperature, on the separation rate of zinc ion in the permeator were experimentally examined.

• Korean Chemical Engineering Research
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• v.52 no.3
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• pp.340-346
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• 2014

Continuous and dense ZIF-7 membranes were successfully synthesized on ${\alpha}-Al_2O_3$ porous substrate via two-step crystallization technique. ZIF-7 seeding layer was first deposited on porous ${\alpha}-Al_2O_3$ substrate by in-situ low temperature crystallization, and then ZIF-7 membrane layer can be grown through the secondary high-temperature crystallization. Two synthesis solutions with different concentration were used to prepare ZIF-7 seeding layer and membrane layer on porous ${\alpha}-Al_2O_3$ substrate, respectively. As a result, a continuous and defect-free ZIF-7 membrane layer can be prepared on porous ${\alpha}-Al_2O_3$ substrate, as confirmed by scanning electron microscope. XRD characterization shows that the resulting membrane layer is composed of pure ZIF-7 phase without any impurity. A single gas permeation test of $H_2$, $O_2$, $CH_4$ or $CO_2$ was conducted based on our prepared ZIF-7 membrane. The ZIF-7 membrane exhibited excellent H2 molecular sieving properties due to its suitable pore aperture and defect-free membrane layer.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.1047-1052
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• 1998

The porous alumina membrane was prepared from aluminum metal(99.8%) by anodic oxidation using DC power supply of constant current mode in aqueous solution of sulfuric, oxalic, phosphoric and chromic acid. Pore size and distribution, membrane thickness, morphology and crystal structure were examined with several anodizing conditions : reaction temperature, electrolyte concentration, current density and electrolyte type. It was found that ultrafiltration membrane was fabricated in electrolyte of sulfuric, and oxalic acid. On the other hand, microfiltration membrane was fabricated in electrolyte of phosphoric, and chromic acid. Also, it was shown that crystal structure of porous alumina membrane prepared in sulfuric, oxalic, and phosphoric acid was amorphous, whereas porous alumina membrane prepared in chromic acid had ${\gamma}$ type of crystal structure.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.133-135
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• 2003

The removal of dissolved oxygen(DO) from water was studied using a poly(vinyliene fluoride)(PVDF) hollow fiber membrane contactor(HFMC) with the vacuum degassing process(VDP), Asymmetric porous PVDF hollow fiber membranes (HFM) for membrane contactor were prepared by a wet phase inversion method. In spinning of these PVDF hollow fibers, dimethy lacetamide (DMAc), LiCl and pure water were used as a solvent, a pore-forming additive and internal/external coagulant, respectively. The characteristics of the structure(pore size, porosity etc.) of the prepared PVDF HFMs as a function of concentration of pore-forming additive in polymer dope solution were studied. Also, the removal efficiency of DO from water according to flow rates of water, using PVDF HFMC with VDP, was studied. The performance of the asymmetric porous PVDF HFMC and a symmetric porous PP HFMC commercialized were compared. As a result, the asymmetric porous PVDF HFMC showed higher removal efficiency of DO than that of a symmetric porous PP HFMC.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.8
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• pp.537-544
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• 2017

The purpose of this study is to analyze the flow characteristics when a staggered hollow fiber membrane module is modeled as a porous medium. The pressure-velocity equation was used for modeling the porous medium, using pressure drop data. In terms of flow characteristics, we compared the case of the "porous medium" when the membrane module was modeled as a porous medium with the case of the "membrane module" when considering the original shape of the membrane module. The difference in pressure drop between the "porous medium" and "membrane module" was less than 0.6%. However, the maximum flow velocity and mean turbulent kinetic energy of the "porous medium" were 2.5 and 95 times larger than those of the "membrane module," respectively. Our results indicate that modeling the hollow fiber module as a porous medium is useful for predicting pressure drop, but not sufficient for predicting the maximum flow velocity and mean turbulent kinetic energy.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.11a
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• pp.142-145
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• 2004

Anion-exchange porous hollow-fiber membranes with a thickness of about 1.2 mm and a pore size of about $0.30{\mu}m$ were used as a supporting matrix to immobilize cycloisomaltooligosaccharide glucanotransferase (CITase). CITase was immobilized to the membrane via anion-exchange adsorption and by subsequent enzymatic cross-linking with transglutaminase, the amount of which ranged from 3 to 110 mg per g of the membrane. The degree of enzyme multilayer binding was equivalent to 0.3 to 9.8. Dextran, as the substrate, was converted into seven- to nine-glucose-membered cycloisomaltooligosaccharides (CI-7, -8, and -9) at a maxi mum yield of $28\%$ in weight at a space velocity of 10 per hour during the permeation of $2.0(w/w)\%$ dextran solution across the CITase-immobilized porous hollow-fiber membrane.

• Journal of environmental and Sanitary engineering
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• v.13 no.3
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• pp.72-78
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• 1998

For investigation into gas permeation characteristics, the porous alumina membrane with asymmetrical structure, having upper layer with 10 nanometer under of pore diameter and lower layer with 36 nanometer of pore diameter, was prepared by anodic oxidation using DC power supply of constant current mode in an aqueous solution of sulfuric acid. The aluminium plate was pre-treated with thermal oxidation, chemical polishing and electrochemical polishing before anodic oxidation. Because the pore size depended upon the electrolyte, electrolyte concentration, temperature, current density, and so on, the the membranes were prepared by controling the current density, as a very low current density for upper layer of membrane and a high current density for lower layer of membrane. By control of current quantity, the thicknesses of upper layer of membranes were about $6{\;}{\mu}m$ and the total thicknesses of membranes were about $80-90{\;}{\mu}m$. We found that the mechanism of gas permeation depended on model of the Knudsen flow for the membrane prepared at each condition.

• Membrane Journal
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• v.16 no.1
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• pp.39-50
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• 2006

Porous chitosan and chitin membranes were prepared by using silica particles as porogen. Membrane preparation was achieved via the following three steps: (1) chitosan film formation by casting an chitosan solution containing silica particles, (2) preparation of porous chitosan membrane by dissolving the silica particles by immersing the film into an alkaline solution and (3) preparation of porous chitin membrane by acetylation of chitosan membrane with acetic anhydride. The optimum preparation conditions which could provide a chitosan and chitin membranes with good mechanical strength and adequate pure water flux were determined. To allow protein affinity, a reactive dye (Cibacron Blue 3GA) was immobilized on porous chitosan membrane. Binding capacities of affinity chitosan and chitin membranes for protein and enzyme were determined by the batch adsorption experiments of BSA protein and lysozyme enzyme. The maximum binding capacity of affinity chitosan membrane for BSA protein is about 22 mg/mL, and that of affinity chitin membrane for lysozyme enzyme is about 26 mg/mL. Those binding capacities are about $several{\sim}several$ tens times larger than those of chitosan and chitin-based hydrogel beads. Those results suggest that the porous chitosan and chitin membranes are suitable in affinity filtration chromatography for large scale separation of proteins.

• Journal of Periodontal and Implant Science
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• v.24 no.1
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• pp.51-63
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• 1994

There has been many attempts to develop a method that can regenerate periodontal tissues that were lost due to periodontal diseasd, but none of them was completely successful. This study was designed to investigate the healing and regeneration of periodontal tissue when bone substitutes such as porous replamineform hydroxyapatite and porous resorbable calcium carbonate were used in combination with oxidized cellulose membrane and collagen absorbable hemostat, compared to a control where only oxidized cellulose membrane or collagen absorbable hemostat were used. Chronic periodontitis was induced on mandibular premolars of and adult dog by placing orthodontic elastic ligatures for 10 weeks. After flap operation, the control group were received oxidized cellulose membrane (control- I )or collagen absorbable hemostat (control- II) only, while one experimental group was given either porous replamineform hydroxyapatite or porous resorbable calcium carbonate in addition to oxidized cellulose membrane (Experimental I-A, I-B), and another experimental group was treated by using either porous replamineform hydroxyapatite or porous resorbable calcium carbonate in addition to collagen absorbable hemostat. (Experimental II-A, II-B) After 56 weeks, healing was histologically analyzed with the following results. 1. Apical migration of junctional epithelium was observed only in areas coronal to the notch for both control and experimental group. 2. Inflammatory cell infiltration was not observed in any groups. 3. Oxidized cellulose membrane and collagen absorbable hemostat were completely resorbed. 4. Newly-formed cementum was observed up to the level where junctional epithelium was located, for both control and experimental groups. 5. Bone formation was limited of the middle portion of the notch in the control group, where as experimental groups showed bone formation up to the level of implant materials coronal to the notch. 6. Minute resorption of apically located portions of implanted materials was observed in experimental group I-B and II-B only.

• Membrane Journal
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• v.10 no.2
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• pp.55-65
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• 2000

The porous silica membrane was prepared from Si(${OC}_2H_5)_4-H_2O$ system by sol-gel method. To investigate the characteristics of gels and porous silica membrane, we examined gels and porous silica membrane using TG-DTA, X-ray diffractometer, IR spectrophotometer, BET, SEM and TEM. The optimum mole ratio of Si(OC$_2$H$_{5}$)$_4$ : $H_2O$ $C_2$H$_{5}$OH for porous silica membrane was 1 : 4.5 : 4. The porous silica membrane was obtained by heat treatment of the gel above 700 $^{\circ}C$. The specific surface area of sintered gel was 3.8 $m^2$/g to 902.3 $m^2$/g at 100 $^{\circ}C$ to 1100 $^{\circ}C$ The pore size of sintered gel was in the range 20 $\AA$~ 50$\AA$. The particle size of sintered gel was 15 nm to 30 nm at 30$0^{\circ}C$ to 700$^{\circ}C$. The performance of the porous silica membrane was investigated for the separation of $H_2$/$N_2$ gas mixture. Gas separation through porous silica membrane depends upon Knudsen flow and surface flow. The veal separation factor($\alpha$) of $H_2$/$N_2$ was 5.17 at 155.15 cmHg and $25^{\circ}C$. The real separation factor($\alpha$), head separation factor($\beta$), and tail separation factor( $\bar{B}$) increased as the pressure of permeation cell Increased.sed.