• Membrane Journal
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• v.11 no.1
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• pp.50-59
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• 2001

Influence of concentration polarization has been investigated on the vapor permeation of VOCs/$N_2$ mixture. Po]y(dimethylsiloxane)(PD,vIS) membrane which had a good affinit~, toward VOCs was emploj,'c'Cl in this study. The chlorinated hydmcarbons which were part of homologous series of chrolomelhane and chrolocthane were used as organic vapor. The vapor permeation experiments were calTied out at various VOCs feed concentrations. operating temperatures and feed flow rates. With decreasing feed flow rate. the membrane perfonnance, that is. penneation rate and selectivity were reduced in the permeation of VOCs/$N_2$ mixture. Especially the reducing of the membrane performance was founel to be more significant when the condensibility of voe was greater. voe content in the feed mixture was higher or operating temperature was lower. These observations were discussed in terms of the influence of con-centration polarizalion on the permeation of VOCSINl mixture through the PDMS membrane.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.96-98
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• 1998

1. 서론 : 팔라듐이나 이의 합금막들은 높은 선택적 투과특성으로 인해 수소 정제나 분리막 반응기와 같은 산업응용 분야에서 매우 높은 관심을 갖고 있다. 상업적으로 이용되고 있는 이러한 막들은 통상적인 metallugical process에 의해 제조괸 self-supported type으로 수소 투과 속도가 낮을 뿐만 아니라 팔라듐 등은 고가의 귀금속이므로 비경제적이다. 따라서 현재 대부분의 연구자들은 기계적 강도를 유지하기 의한 다공성 지지체 위에 얇은 금속 박막을 코팅함으로서 투과성을 높이는 동시에 경제적인 복합막 형태의 막을 만드는데 연구의 촛점을 맞추고 있다. 이러한 형태의 막을 제조하기 위한 금속 박막 제조법은 무전해 도금법(electroless deposition), 화학증착법(CVD), 스퍼터링(sputtering), 전해도금법(electrodeposition) 등이 시도되었다. 그러나 수소에 대한 우수한 선택적 투과 특성을 갖기 의해서는 대부분 5$\mu$m 이상의 두꺼운 막을 제조하였으며 이보다 얇은 막의 제조에 한계가 있기 때문에 이들 막에 대한 기체 투과 특성에 대한 연구결과는 많지 않다. 본 연구에서는 기존의 전기도금법을 응용한 소위 'vacuum electrodeposition' 이란 새로운 기술을 도입함으로써 우수한 선택적 투과성을 갖는 2$\mu$m 이하의 팔라듐 합금 박막 제조를 가능하게 하였다. 지지체 표면의 거칠음 정도, 평균 기공 크기 등의 지지체 성질의 조절에 의한 금속 박막의 핀홀을 최소화함으로써 질소와 같은 inert gas의 투과도는 거의 없게 유지하는 동시에 금속 박막 두께, 결정 구조(e.g. grain size), 합금 조성 등을 조절함으로써 수소의 투과도를 높이고자 하였다. 있다. 후자의 경우, 미량의 과산화수소수 (1~10,000 ppm)를 이용해 처리 해주는 방법의 경우 경제적으로 큰 장점이 있고, 처리가 단순하다는 장점이 있으나 과산화수소수 자체에 포함하고 있는 높은 impurit level, 그리고 처리후 장시간의 flushing time을 가져야 한다는 단점등이 존재 하고 있다.요구된다. 몰입이 가능하여 임계치가 저하된 것으로 여겨진다. 또한 광학적 이득의 존재는 이 구조에 의한 극단파장 반도체 레이저다이오드의 실현 가능성을 나타내는 것이다.548 mL에 비해 통계학적으로 의의 있게 적었다(p<0.05). 결론: 관상동맥우회로 조성수술에서 전방온혈심정지액을 사용할 때 희석되지 많은 고농도 포타슘은 fliud overload와 수혈을 피하고 delivery kit를 사용하지 않음으로써 효과적이고 만족할 만한 심근보호 효과를 보였다.를 보였다.4주까지에서는 비교적 폐포는 정상적 구조를 유지하면서 부분적으로 소폐동맥 중막의 비후와 간질에 호산구 침윤의 소견이 특징적으로 관찰되었다. 결론: 분리 폐 관류는 정맥주입 방법에 비해 고농도의 cisplatin 투여로 인한 다른 장기에서의 농도 증가 없이 폐 조직에 약 50배 정도의 고농도 cisplatin을 투여할 수 있었으며, 또한 분리 폐 관류 시 cisplatin에 의한 직접적 폐 독성은 발견되지 않았다이 낮았으나 통계학적 의의는 없었다[10.0%(4/40) : 8.2%(20/244), p>0.05]. 결론: 비디오흉강경술에서 재발을 낮추기 위해 수술시 폐야 전체를 관찰하여 존재하는 폐기포를 놓치지 않는 것이 중요하며, 폐기포를 확인하지 못한 경우와 이차성 자연기흉에 대해서는 흉막유착술에 더 세심한 주의가 필요하다는 것을 확인하였다. 비디오흉강경수술

• Membrane Journal
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• v.22 no.4
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• pp.280-283
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• 2012

The study is aiming to prepare supported ionic liquid membranes for carbon dioxide separation efficiently. The ionic liquid, [bmim][${PF_6}^-$] (1-butyl-3-methyl-imidazolium hexafluorophosphate) was fixed in the pores of PVDF micro-filtration membrane with a nominal pore size 0.1 ${\mu}m$. The permeabilities of $N_2$, $H_2$ and $CO_2$ gases through the prepared ionic liquid membrane were 0.075, 0.203 and 1.380 GPU, respectively. The selectivities of $CO_2/N_2$, $H_2/N_2$ were 14.2 and 2.69, respectively. Also, the supported ionic liquid membrane could be operated stably up to 2.0 bar with the immobilization of ionic liquid in the pores.

• Membrane Journal
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• v.7 no.4
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• pp.191-198
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• 1997

Membrane formation mechanism by the phase inversion has been investigated in order to control the membrane morphology. It was found that finger-like structures were obtained when the heat of mixing between the solvent and non-solvent is exothermic, while sponge-like structures were obtained when they are endothermic in polystyrenes as well as in polyimides (Torlon and polyimide made frorn 3,3'4,4'-benzophenontetracarboxylic diahmydride and 1,4-phenylene diarnine) membranes. This concept was applied to control the morphology of polysulfone membranes simply by adding a solvent additive by adjusting the heat of mixing. A crude, but simple, relationship between the heat of mixing and the exchange rate of the solvent with non-solvent has been also developed.

• Membrane Journal
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• v.25 no.1
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• pp.42-47
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• 2015

In this study, PEBAX[poly(ether-block-amide)]-NaY zeolite composite membranes were prepared, and those prepared membranes were studied on permeability of $C_3H_6$ and $C_3H_8$, and selectivity ($C_3H_6/C_3H_8$). NaY zeolite particles in PEBAX-NaY zeolite composite membranes was dispersed as aggregated particles with the size $0.5{\sim}2.5{\mu}m$ by SEM observation. TGA measurement showed the weight loss change resulted from the amount of NaY zeolite when NaY zeolite was added into PEBAX. By gas permeation experiment, the permeabilities of $C_3H_6$ and $C_3H_8$ were decreased by the more addition NaY zeolite in PEBAX. Overall, $C_3H_6$ was having higher permeability than $C_3H_8$. The selectivity $C_3H_6/C_3H_8$ was decreased by the more NaY zeolite in PEBAX.

• Membrane Journal
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• v.25 no.1
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• pp.27-31
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• 2015

PEBAX[poly(ether-block-amide)]-NaY zeolite composite membrane was studied on the permeability of penetrant $H_2$, $N_2$, $CO_2$ and $CH_4$ and the selectivity. When the NaY zeolite contents of PEBAX-NaY zeolite membranes were increased, the permeability of $H_2$ was increased, but the permeability of $N_2$, $CH_4$ and $CO_2$ was decreased. By the addition of NaY zeolite into PEBAX, the gas selectivity for $H_2$, $N_2$ and $CO_2$ was decreased except the increase of selectivity of $H_2/N_2$. $CO_2/N_2$, $H_2/CO_2$ and Gas/$CH_4$. The highest selectivity among these gases was from $CO_2$. In particular, the gas selectivity for $CO_2$ was the greatest with a value of 12~156.

• Membrane Journal
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• v.15 no.2
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• pp.157-164
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• 2005

In this study, composite hollow fiber membranes were developed for the recovery of olefin monomers in polyolefin industry off-gases. Polyetherimide (PEI) hollow fiber support membranes were fabricated from spinning solutions containing PEI, NMP and polyethylene glycol (PEG). The influence of dope solution and inner coagulant composition on the permeation properties and structure of hollow fiber supports was examined. PDMS was used as a selective layer and coated on PEI hollow fiber support. The thickness of active layer was controlled by changing coating solution concentration. The permeation properties of hollow fiber supports and composite membranes were characterized with a pure gas permeation test. The optimized composite hollow fiber membrane has $10\;{\mu}m$ selective layer and shows excellent separation performance; the ideal selectivity of olefins over nitrogen is in the following order: 1-butylene (6.4) > propylene (17) > ethylene (97), which selectivity data are similar to the intrinsic olefin/nitrogen selectivities of PDMS. This confirms that the new composite hollow fiber membranes suitable for olefin off-gas recovery has developed successfully.

• Membrane Journal
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• v.33 no.3
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• pp.94-109
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• 2023

1,3-Dioxolane is an exciting material that has attracted widespread interest in the chemical, paint, and pharmaceutical industries as a solvent, electrolyte, and reagent because 1,3-dioxolane is not toxic, carcinogenic, explosive, auto-flammable, and multifunctional, and due to their excellent miscibility in most organic and aqueous solvent conditions. Recently, this material has received increasing attention as a CO₂-selective polymer precursor to separating CO₂ from flue gas and natural gas mixtures. Poly(1,3-dioxolane) (PDXL) possesses higher ether oxygen content than polyethylene oxide (PEO), which demonstrates superior membrane CO₂/N₂ separation properties owing to their polar ether oxygen groups exhibiting strong affinity toward CO₂. Thus, PDXL-based membranes displayed an outstanding CO₂ solubility selectivity over non-polar (N₂, H₂, and CH₄) gases. However, the polar groups of PDXL, like PEO, promote chain packing efficiency and cause polymer crystallization, thereby reducing its gas permeability, which should be improved. In this short review, we discuss the recent advancement and limitations of PDXL membranes in gas separation applications. To conclude, we provide future perspectives for inhibiting the limits of 1,3-dioxolane-based polymers in the CO₂ separation process.

• Journal of the Korean Ceramic Society
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• v.29 no.12
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• pp.970-980
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• 1992

${\gamma}-alumina$ membranes were prepared by sol-gel dip coating or pressurized coating of boehmite sols on slipcasted ${\gamma}-alumina$ support tubes. The particle size of sols synthesized via the modified Yoldas-method could be controlled below 5 mn according to the mole ratio of nitric acid/aluminumtri-sec-butoxide (0.07~1.0). The reproducible crack-free composite membranes were produced by the 2nd dip coating or the pressurized coating technique using very stable sols with the particle size of 45 nm. Nitrogen gas permeability through the top-layer in the composite membrane was about $70~55{\times}10^{-7}\;mol/m^2{\cdot}s{\cdot}Pa$. The thermal stability of the top layer was proved to be good enough upto the heat-treatment temperature of $500^{\circ}C$.

• Membrane Journal
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• v.33 no.6
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• pp.362-368
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• 2023

This research article explores the application of Polymer of Intrinsic Microporosity (PIM-1) as a cutting-edge material for CO₂ gas separation membranes in response to the escalating global concern over climate change and the imperative to reduce greenhouse gas emissions. The study delves into the synthesis, molecular weight control, and fabrication of PIM-1 membranes, providing comprehensive insights through various characterization techniques. The intrinsic microporosity of PIM-1, arising from its unique crosslinked and rigid structure, is harnessed for selective gas permeation, particularly of carbon dioxide. The article emphasizes the tunable chemical properties of PIM-1, allowing for customization and optimization of gas separation membranes. By controlling the molecular weight, higher molecular weight (H-PIM-1) membranes are demonstrated to exhibit superior CO₂ permeability and selectivity compared to lower molecular weight counterparts (L-PIM-1). The study's findings highlight the critical role of molecular weight in tailoring PIM-1 membrane properties, contributing to the advancement of next-generation membrane technologies for efficient and selective CO₂ capture-an essential step in addressing the pressing global challenge of climate change.