• Membrane Journal
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• v.33 no.6
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• pp.383-389
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• 2023

A high-performance forward osmosis (FO) membrane was prepared using polyethylene glycol diacrylate (PEGDA) hydrogel as a support layer. Through the UV-induced polymerization and subsequent phase separation of PEGDA, the crosslinked, hydrophilic, and porous PEGDA suppor layer was obtained. To achieve high FO flux and salt selectivity using the fabricated PEGDA support, a selective layer was synthesized via the toluene-assisted interfacial polymerization (TIP), in which toluene is used as an organic solvent. The prepared PEGDA-based FO membrane showed higher FO water flux and lower salt selectivity compared with commercial HTI membranes using 1.0 M NaCl draw solution and DI water feed solution. We propose the strategy to fabricate high-performance FO membranes utilizing supports formed with new hydrophilic materials and fabrication processes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.642-644
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• 1999

We have prepared the plasma-polymerized membrane for pervaporation of organic-liquid mixtures by the plasma polymerization technique. Plasma polymerization techniques were utilized in the development of hydrophilic composite membranes having high hydrogen ion permeability and excellent dimensional stability. To develop an organic liquid permselective Membrane, suppressing membrane swearing as well as enhancing the solubility difference is impotant. the objectives of the present study are to disign a suitable membrane for an organic-mixture system by the control of the plasma-polymer solubility.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.04b
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• pp.56-58
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• 1997

최근 polyolefin계열의 고분자 분리막이 많이 사용되고 있는데 특히 그 중 polypropylene막은 특성상 내약품성 및 내열성이 뛰어나 막 손상이나 성능 저하가 비교적 적은 고분자 막으로 평가되고 있다. 그러나 재질의 소수성 특성 때문에 심각한 fouling을 유발하게 되어 이를 방지하기 위해 막 표면을 hydrophilic agent로 개질 시켜 fouling을 제어하는 기술이 진행되고 있다. 일반적으로 막 재질을 개질 시키기 위하여 sulfonating agents, ozone, 그리고 hydrophilic monomer등을 grafting하는 방법들이 사용되고 있는데, 이는 공정상의 어려움이 있고 완벽한 친수성의 부여를 기대하기가 어렵다. 또한 막 기공 구조의 변화와 붕괴를 초래한다는 단점이 있다. 이밖에 hydrophilizing agent 등을 이용하여 wetting시킴으로써 일시적인 친수화 처리를 하는 방법이 있다. 그러나 이 방법은 membrane matrix로 부터 hydrophilizing agent가 새어 나가므로 영구적으로 사용할 수 없으며, 특히 의료용 분리막으로 이용될 경우 유출된 hydrophilizing agent가 cell membrane을 공격하여 cell 분해와 같은 인체에 해로운 결과를 초래하기 때문에 부적당하다. 최근 들어 저온 plasma를 이용한 표면 개질의 방법이 연구되고 있는데, 이는 plasma가 고분자 물질의 구조나 화학적 반응성과는 상관없이 모든 고분자 물질의 표면을 일정하게 개질 시킬 수 있으며 여타의 다른 방법들과는 달리 막 제조시 residual solvent의 문제점과 swelling의 문제점들이 발생하지 않는 장점 때문에 최근 각광받고 있는 기술 중의 하나이다. 또한 다른 방법에 비해 막과 plasma와의 강한 흡착력 때문에 영구적 친수성을 가지게 할 수 있다. 본 연구에서는 저온 plasma를 이용한 표면 개질이 막의 친수성 향상 및 fouling 방지에 미치는 영향에 대하여 조사하였다.

• Membrane Journal
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• v.27 no.1
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• pp.92-103
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• 2017

In this study, electrochemical performance of the hydrophilized separator for the lithium ion battery is studied. The polyolefin based material used as the separator for the lithium ion battery is hydrophobic, and the electrolytic solution using a carbonate-based organic solvent is hydrophilic. Therefore, the polyolefin separator is hydrophilized using various hydrophilic polymers because lithium ion battery uses an aqueous electrolyte solution. In order to evaluate change of the coated separator, the performances of separator in terms of surface morphology, porosity and the wettability are investigated. Finally, the resistance and the ionic conductivity of separator coated with lithium ion are measured to evaluate the performance of lithium ion battery. Separator coated with PMVE shows good hydrophilicity and excellent ionic conductivity because the porosity of the separator is maintained. We can confirm that this property makes potential candidates for lithium ion battery.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.639-645
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• 2008

The objectives of this research are to (1) observe changes in particle size distribution due to formation of microflocs during coagulation process (2) identify the membrane fouling potential on cross flow system (3) investigate the mechanism of membrane fouling. The rate of flux decline for the hydrophobic membrane was significantly greater than for the hydrophilic membrane, regardless of pretreatment conditions. The pretreatment of the raw water significantly reduced the fouling of the UF membrane. Also, the rate of flux decline for the hydrophobic membrane was considerably greater than for the hydrophilic membrane. Applying coagulation process before membrane filtration showed not only reducing membrane fouling, but also improving the removal of dissolved organic materials that might otherwise not be removed by the membrane. That is, during the mixing period, substantial changes in particle size distribution occurred under rapid and slow mixing condition due to the simultaneous formation of microflocs and NOM precipitates. Therefore, combined pretreatment using coagulation not only improved dissolved organics removal efficiency but also flux recovery efficiency.

• Membrane Journal
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• v.29 no.6
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• pp.362-376
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• 2019

In this study, hydrophilic coating characteristics of PVDF [poly(vinylidene fluoride)] hollow fiber membranes with flower type cross-section prepared by thermally induced phase separation were studied. The hollow fiber used in this study was provided from PureEnvitech Co. Ltd., and the hydrophilic coating experiment was performed with different concentration and number of coating of PEBAX 1657, 2533 and 3533 block copolymer solution using a dip coating method. The hydrophilic coated hollow fiber membrane was characterized to scanning microscope and contact angle measurements to determine the degree of hydrophilization. As a result of SEM characterization, it was confirmed that the thickness of the coating layer increased as the coating concentration increased and the number of coatings increased. Contact angle of surface of hollow fibers decreased as the concentration of the coating solution increased and the number of coatings increased. Gas permeance of oxygen gas was measured for the application of the hydrophilized hollow fiber to Membrane Areated Biofilm Reactor. As a result of gas permeation test, it was confirmed that gas permeance decreased with increasing coating concentration and number of coatings, and the more hydrophilized hollow fiber coated with PEBAX 1657 showed lower gas permeance than those coated with PEBAX 2533 and 3533.

• YAKHAK HOEJI
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• v.60 no.1
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• pp.36-45
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• 2016

This study was aimed to enhance the percutaneous absorption of tizanidine hydrochloride (TZ) across Strat-M$^{TM}$ artificial membrane and excised hairless mouse skin using various vehicles and chemical permeation enhancers. Solubility studies were performed using hydrophilic and lipophilic vehicles. To initially evaluate vehicle effects on skin permeation, Strat-M$^{TM}$ membrane was adopted using Franz-type diffusion cells loaded with 0.4 mg donor dose. Effects of fatty acids on the permeation of TZ from PG and PGMC were compared, and the effects of various hydrophilic vehicles in the presence of linoleic acid were studied using excised hairless mouse skin specimens. The mean solubility (mg/ml) of TZ in hydrophilic vehicles was higher: water > PG > DMSO > ethanol > PEG 200 > NMP > PEG 300 > PEG 400 > DGME, and solubilities in lipophilic vehicles such as PGMC, PGMC, IPM, Captex 200 and Captex 300 were much less than 1.0 mg/ml. Permeation rates through StratTM membrane from pure vehicles were in the rank order: PGMC ${\geq}$ LBF > DMSO ${\geq}$ NMP ${\geq}$ PGML ${\geq}$ PG ${\geq}$ PEG 200 ${\geq}$ DGME ${\geq}$ EtOH. However, permeation rates of TZ through hairless mouse skin from pure vehicles were very low, although PG showed the highest flux ($1.66{\pm}0.28{\mu}g/cm^2{\cdot}hr$). Therefore, PG was selected in further studies. Addition of enhancers (3 v/v%) into PG markedly increased the flux (${\mu}g/cm^2{\cdot}hr$): oleyl alcohol ($14.9{\pm}3.1$) ${\geq}$ oleic acid ($14.5{\pm}1.6$) ${\geq}$ linoleic acid ($13.7{\pm}1.3$) > capric acid ($4.4{\pm}0.6$) > caprylic acid ($2.1{\pm}0.4$). Among hydrophilic vehicles with linoleic acid, PG and DMSO revealed relatively higher permeation for TZ. Increase of donor dose in PG resulted in dose-dependent permeation fluxes. These results suggest that permeation properties of TZ from nonaqueous solutions are markedly different between Strat-$M^{TM}$ membrane and excised hairless mouse skin, and transdermal delivery of TZ would be feasible with a combination of PG and enhancers.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2001.05a
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• pp.140-140
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• 2001

Porins are major outer membrane proteins which produce non-specific aqueous channels across the membrane that permit the diffusion into the bacterial cells of hydrophilic compounds including sugars, amino acids, and antibiotics. In some gram-negative organisms, antibiotic resistance can be induced by mutational loss of channel that causes a decrease in outer membrane permeability. (omitted)

• Proceedings of the Membrane Society of Korea Conference
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• 2005.11a
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• pp.219-220
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• 2005

• Applied Science and Convergence Technology
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• v.23 no.5
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• pp.248-253
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• 2014

Air Gap Membrane Distillation (AGMD) is one of several technologies that can be used to solve problems fresh water availability. AGMD exhibits several advantages, including low conductive heat loss and higher thermal efficiency, due to the presence of an air gap between the membrane and condensation wall. A previous study by Bhardwaj found that the condensation surface properties (materials and contact angle) affected the total collected fresh water in the solar distillation process. However, the process condition differences between solar distillation and AGMD might result in different condensation phenomena. In contrast, N. Miljkovic showed that a hydrophobic surface has higher condensation heat transfer. Moreover, to the best of our knowledge, there is no study that investigates the effect of condensation surface properties in AGMD to overall process performance (i.e. flux and thermal efficiency). Thus, in this study, we treated the AGMD condensation surface to make it hydrophobic or hydrophilic. The condensation surface could be made hydrophilic by immersing and boiling plate in deionized (DI) water, which caused the formation of hydrophilic aluminum hydroxide (AlOOH) nanostructures. Afterwards, the treated plate was coated using hexamethyldisiloxane (HMDSO) through plasma-enhanced chemical vapor deposition (PECVD). The result indicated that condensation surface properties do not affect the permeate flux or thermal efficiency significantly. In general, the permeate flux and thermal efficiency for the treated plates were lower than those of the non-treated plate (pristine). However, at a 1 mm and 3 mm air gap, the treated plate outperformed the non-treated plate (pristine) in terms of permeate flux. Therefore, although surface wettability effect was not significant, it still provided a little influence.