• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.235-241
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• 2011

This study was performed to investigate the characteristics of nutrient removal of municipal wastewater in the submerged membrane bioreactor by addition of alum directly into aerobic tank. Membrane bioreactor consists of three reactors such as two intermittent anaerobic tanks and the aerobic tank with hollow fiber membrane. The removal efficiencies of $COD_{cr}$, BOD, SS, TN and TP on the membrane bioreactor were 94.0%, 99.1%, 99.9%, 66.9%, and 58.9%, respectively. In addition, The removal efficiencies of $COD_{cr}$, BOD, SS, TN and TP on the membrane bioreactor with alum addition were 93.4%, 99.0%, 99.9%, 63.2%, and 96.8%, respectively. There was little difference between them on the nutrient removal efficiencies except phophorus removal. The estimated sludge production, specific denitrification rate, specific nitrification rate and phosphorus removal content on the membrane bioreactor were 1.76 kgTSS/d, $0.055mgNO_3-N/mgVSS{\cdot}d$, $0.031mgNH_4-N/mgVSS{\cdot}d$, and 0.095 kgP/d, respectively. And The estimated sludge production, specific denitrification rate, specific nitrification rate and phosphorus removal content on the membrane bioreactor with alum addition were 2.90 kgTSS/d, $0.049mgNO_3-N/mgVSS{\cdot}d$, $0.030mgNH_4-N/mgVSS{\cdot}d$, and 0.160 kgP/d, respectively. The alum content added was 1.7 molAl/molP on an average. The increasing ratio of tran-membrane pressure on the membrane bioreactor was $0.0056kgf/cm^2{\cdot}compared$ to $0.0033kgf/cm^2{\cdot}d$ on the membrane bioreactor with alum addition. There was a slightly reduction effect on membrane fouling by alum addition.

• Membrane Journal
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• v.9 no.1
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• pp.43-50
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• 1999

The effects of water vapor on the permeation rates of oxygen and nitrogen through poly sulfone hollow-fiber membrane were investigated. The permeation rates of both 02 and $O_2$ were decreased significantly owing to the presence of water vapor. The permeation rate of oxygen with 100% relative humidity was reduced by as much as 20%, while the permeation rate of nitrogen decreased by 14% at 30 "C and 3kgf/$cm^2$ of upstream pressure. The permeation rates of $O_2$ were declined monotonously with running time and arrived at steady state values by the presence of water vapor. However, those of $N_2$ increased tentatively and then decreased to the steady state.tate.

• Journal of Biomedical Engineering Research
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• v.23 no.1
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• pp.27-32
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• 2002

The purpose of this study was to evacuate the effects of the number of tied hollow fibers in a novel membrane oxygenator that satisfied the limiting factor of minimizing the friction loss in the intravascular blood flow Pattern. The membrane oxygenator is a bundle consisted of several hundred ho1low fibers haying the outside diameter of 380 $\mu m$ and the axial jacket length of 600 mm. The eight different variation of tied hollow fibers in a bundle were designed. and the liquid flow pattern was controlled by a pump. The liquid pressure drop was measured by in vitro experiments using water and g1ycero1. Uniform blood flow pattern was observed for each number of tied hollow fibers. Pressure drop was 13-16 mmHg outside of the membrane oxygenator consisting of up to 700 ho1low fibers. More effective contact of liquid with the tied ho1low fibers was observed as a decrease in the number of the tied hollow fibers. and resulted in the enhancement of the friction tractor

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.419-420
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• 2010

• Membrane Journal
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• v.16 no.2
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• pp.133-143
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• 2006

A hollow fiber membrane containing BSA as ligand was Prepared by radiation-induced grafting GMA onto a porous polyethylene hollow fiber and subsequent reacting with DEA and TEA. The density of the DEA and TEA of the membrane were 3.4 mmol/g, 1.7r mmol/g, respectively. The DEA membrane exhibited a higher amount of than the TEA membrane. BSA was immobilized by the graft chains during the permeation of BSA solution throught the DEA and TEA membrane. The BSA was adsorbed in multilayer binding of 8 onto the DEA membrane whereas adsorption onto the TEA membrane remained constant. A two-stage stepwise BTC was observed due to independent chiral recognition for L, D-Trp solution by DEA-BSA membrane.

• Proceedings of the Membrane Society of Korea Conference
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• 1993.04a
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• pp.36-37
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• 1993

상전이 공정에 의해 제조된 기체분리용 중공사막은 1차적으로 방사원액의 조성과 내.외부응고제의 조성, 중공사 방사조건 그리고 후처리 과정에 의해서 전체적인 구조가 결정되어진다. 특히 기체 분리에 이용되는 Nonprous Membrane의 경우 Dense Skin의 Thickness와 Pinhole의 유무에 따라 투과성과 선택성에 커다란 영향을 미친다. 따라서 최근에는 Dense Skin의 초박막화와 Pinhole이 없는 비대칭막 제조등 폭넓은 연구가 이루어지고 있다. 본 연구에서는 CO$_2$ Gas 분리용 Polyetherimide 중공사막을 제조하여, 중공사막 제조조건과 후처리 조건에 따른 $CO_2/N_2$ Gas의 분리계수를 측정하였다.

• Membrane and Water Treatment
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• v.9 no.1
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• pp.43-51
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• 2018

Hollow fiber (HF) membranes are gaining wide interest over flat membranes due to their compaction and high area to surface volume ratio. This work addresses the fabrication of HF from polysulfone (PS) and polyethersulfone (PES) using N-methylpyrrolidone (NMP) as solvent in addition to other additives to achieve desired characteristics. The semi-pilot spinning system includes jacketed vessel, four spinneret block, coagulation and washing baths in addition to dryer and winder. Different parameters affecting dry-wet spinning phase inversion process were investigated. Dope compositions of PES, NMP and polyvinyl pyrrolidone (PVP) of varying molecular weights as additive were addressed. Some critical parameters of importance were also investigated. Those include dope flow rate, air gap, coagulation & washing baths and drying temperatures. The measured dope viscosity was in the range from 1.7 to 36.5 Pa.s. Air gap distance was adjusted from 20 to 45 cm and coagulation bath temperature from 20 to $46^{\circ}C$. The HF membranes were characterized by scanning electron microscope (SEM), atomic force microscope (AFM) and mechanical properties. Results indicated prevalence of finger like structure and average surface roughness from about 29 to 78.3 nm. Profile of stress strain characteristics revealed suitability of the fibers for downstream interventions for fabrication of thin film composite membrane. Different empirical correlations were formulated which enable deeper understanding of the interaction of the above mentioned variables. Data of pure water permeability (PWP) confirmed that the fabricated samples fall within the microfiltration (MF)-ultrafiltration (UF) range of membrane separation.

• KSBB Journal
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• v.9 no.3
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• pp.332-338
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• 1994

Solubilization phenomena of a protein in a reversed micellar solution were investigated and a hollow fiber membrane extractor was tested for reversed micellar protein extraction equipment. Alkaline protease was used as a model protein compound and the reversed micellar solution was consisted of AOT and isooctane. It was found that protein solubilization was strongly influenced by ionic strength and pH. The distribution coefficient of the protease between the aqueous solution and the AOT/isooctane solution was also observed to be as high as 4.0 within the scope of this experiment. A hollow fiber membrane extractor was constructed and tested for the protein extraction. The overall mass transfer coefficient at a typical experimental condition of this study was observed to be $6.7{\times}10^{-5}cm/s$. It was also found that the mass transfer resistance on reversed micellar solution was the dominant resistance for the protein transfer.

• Membrane Journal
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• v.2 no.1
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• pp.67-73
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• 1992

The effects of after-treatment condition on the permeability of polysulfone hollow fiber membranes were investigated. It was well known that the permeability of and the rejection of hollow fiber membranes prepared by dry-wet spinning technique was highly affected by spinning conditions such as composition of spinning solution, inner and outer coagulant and spinning height. But these are also governed by after-treatment condition such as drying, hot water treatment and glycerine treatment. Since it was difficult to remove DMAc and NMP in membranes by washing with in cold water and even traces of such solvent affected the reproducibility of the membrane characteristics, the hot water-treatment should be required.

• Membrane and Water Treatment
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• v.15 no.2
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• pp.79-88
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• 2024

Modification of Polyvinylidene fluoride (PVDF) hollow fiber membranes (HFMs) characteristics and performance were investigated via post treatment using different oxidants. sodium hypochlorite (NaOCl), hydrogen peroxide (H₂O₂) and potassium persulfate (KPS). Fourier transform infrared (FTIR) and Proton nuclear magnetic resonance (¹H-NMR) results revealed no structural differences after post treatment. Cross-sectional micrographs show finger-like structures at the outer and inner walls of the HFMs and sponge-like structures in middle, where NaOCl and KPS post treated fibers exhibited a decrease in finger-like structures in addition to aggregates appearing on the surface, consequently leading to an increase in the surface roughness (Ra) from 48 nm to 52.8nm and 56 nm, respectively. Hydrogen peroxide post treatment only was observed to decrease the water contact angle from 98° to 81.4°. It was also observed that the elongation at break and the modulus deceased after NaOCl post treatment from 34.5 to 28.5% and from 19.3 Mpa to 16.6 Mpa, respectively. Moreover, pure water flux after H₂O₂ post treatment increased from 87.8 LMH/bar to 113 LMH/bar at 0.45 bar, while no changes were detected for the methylene blue dye rejection (74%) between raw and hydrogen peroxide post treated fibers at the same pressure. According to the findings hydrogen peroxide post treated PVDF HFMs have the most uniform surfaces, with almost no alterations in structural and mechanical properties or porosities with enhanced hydrophilicity and pure water flux maintaining appropriate rejection. Therefore, it is considered an efficient surface modifying agent for UF/NF membranes or low-pressure separators.