• Journal of the Korean Applied Science and Technology
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• v.32 no.1
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• pp.85-92
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• 2015

The 50 mole% HCl doped polyaniline(PAni) was synthesized by polymerization of aniline in the presence of hydrochloric acid and ammonium persulfate(APS) as dopant and oxidant, respectively. Then, conducting biodegradable cellulose acetate composite films were also prepared with PAni in acetone to find their applicability to antistatic packaging materials. The tensile strength of PCA05 film with 5 wt% of PAni was decreased by 27% from $377.1kg_f/cm^2$ for CA film itself to $275.2kg_f/cm^2$. Elongation was also decreased from 7.65% to 4.35%. Surface registance of $7.0{\times}10^9{\Omega}/sq$ could be achieved for the PCA containing 5 wt% of PAni. Therefore, this PCA05 film can be applied to antistatic package film for electronic board. In addition, decomposition temperature of these PCA films obtained by thermogravimetric analysis(TGA) was decreased with the amount of PAni in PCA films, and the final weight of char was directly proportional to PAni contents. From this thermal result we can calculate the content of PAni in unknown PCA films.

• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.68-73
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• 2017

The removal of particulate matter ranging from $0.01{\mu}m{\sim}10{\mu}m$ can be performed by using membrane filters composed of fibers. Electrospinning techniques offer the production of very thin fibers with a uniform fiber diameter over conventional techniques including template synthesis, melt-blown, phase separation, etc. Air filtration will be improved with electrospun membranes due to the open pore structures, high porosity, and large surface area of the membranes. In the present study, filtration efficiency increased with pore size decrease and fiber density increase induced by carbon nanotube and the increased CA (cellulose acetate) concentration during electrospinning process.

• Proceedings of the Membrane Society of Korea Conference
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• 1991.04a
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• pp.15-18
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• 1991

본 연구에서는 박막화를 위한 수면전개법을 이용하여 기체분리능을 향상시키기 위한 복합막을 개발하고자 수면전개 적층복합막을 제조하여 기체투과특성실험을 행하였다. 실험에 사용한 고분자재질은 투과성이 우수한 Cellulose Acetate(CA)와 Polystyrene(PS)을, 선택성이 우수한 Polyvinylchloride(PVC)이었다. 이들 막에 대한 적층형태와 방법에 대한 효과를 검토하고 blend막과도 기체투과특성을 비교하였다.

• Polymer(Korea)
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• v.32 no.4
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• pp.322-327
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• 2008

In this study, a multi-layered pellet was composed of a seed layer including a water-swellable agent and a drug layer containing doxazosin as a model drug, a porous membrane and a castor oil layer to control drug release. The pellet is prepared by a fluidized bed coating method. To confirm drug release from polymer blending in multi-layered pellet system, it is prepared by containing different ratio such as hydroxypropylmethylcellulose (HPMC) : ethyl cellulose (EC) in drug layer and cellulose acetate(CA) : Eudragit RS in membrane. Also, to confirm the effect of oil in drug release, castor oil is coated. As a result, we observed regularly spherical pellet with diameter of $1500{\mu}m$. Release pattern of drug is confirmed by dissolution tester in aqueous media. The more the ratio of EC in drug layer, CA in membrane, and castor oil layer in pellet, the less the drug release is observed. Formation and the amount of pores in membrane is observed by SEM.

• KSBB Journal
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• v.28 no.4
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• pp.225-229
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• 2013

Bovine Carbonic anhydrase (BCA) was immobilized on a submicro-porous membrane through covalent immobilization. The immobilization was conducted on the porous membrane surface with the treatment of polyethyleneimine, glutaraldehyde, and the anhydrase, in sequence. The immobilization was confirmed using X-ray photon spectrometer. The pH values of carbon-dioxide saturated solution with buffer were monitored with respect to time to calculate the catalytic activities of hydration of carbon-dioxide for free and immobilized CA. The catalytic rate constant values for free CA, immobilized CA on polystyrene nanoparticles, and immobilized CA on a porous cellulose acetate membrane were 0.79, 0.67, and 0.56 $s^{-1}$, respectively. Reusability was studied up to 10 cycles of $CO_2$ sequestration. The activity for the CA immobilized on the membrane was kept to 95% after 10 cycles, and comparable to the CA on the nanoparticles. The stabilities for heat and storage were also investigated for the three cases. The results suggested that the CA immobilized the membrane had the least loss rate of the activity compared to the others. From this study, the porous membrane was feasible as a carrier for the CA immobilization in hydration and sequestration of carbon-dioxide.

• Membrane and Water Treatment
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• v.4 no.2
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• pp.143-155
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• 2013

Four membranes were used to separate Chlorella sp. from their culture medium in cross-flow microfiltration (MF) experiments: cellulose acetate (CA), cellulose nitrate (CN), polypropylene (PP) and polyvinylidenefluoride (PVDF). It was found that the hydrophilic CA and CN membranes with a pore size of 1.2 ${\mu}m$ exhibited the best performances among all the membranes in terms of permeation flux. The hydrophobicity of each membrane material was determined by measuring the angle between the water (liquid) and membrane (solid). Contact angle measurements showed that deionized (DI) water had almost adsorbed onto the surfaces of the CA and CN membranes, which gave $0.00^{\circ}$ contact angle values. The PP and PVDF membranes were more hydrophobic, giving contact angle values of $95.97^{\circ}$ and $126.63^{\circ}$, respectively. Although the pure water flux increased with increasing pore diameter (0.8 < 1.2 < 3.0 ${\mu}m$) in hydrophilic CA and CN membranes, the best performance in term of filtration rate for filtering a microalgae suspension was attained by membranes with a pore size of 1.2 ${\mu}m$. The fouled membrane pore sizes and pore blocking were inspected using a scanning electron microscope (SEM). MF with large pore diameters was more sensitive to fouling that contributed to intermediate blocking, where the size of the membrane pores is almost equivalent to that of cells.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.3
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• pp.312-317
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• 2005

The 15 month pilot study was performed to investigate the effect of pretreatment by monochloramine ($NH_2Cl$) on the performance of RO membranes made of cellulose acetate (CA) and polyamide (PA). Both RO membranes experienced severe biological fouling without any pretreatment during the treatment of highly organic surface water in Florida, USA. Feed monochloramination at 5 mg/L significantly minimized productivity loss by effective control of biofouling. The CA membrane did not show any structural damages by monochloramine, while the PA membrane suffered from a gradual loss of membrane integrity by chlorine oxidation, which was characterized as an increase in productivity and a decrease in selectivity. The degradation of PA membrane increased with increasing monochloramine dose.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.10a
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• pp.46-47
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• 2013

We prepared biostimulant balls using sea sediment mixed with biostimulants viz acetate, nitrate and sulfate. The Biostimulant balls were coated with Cellulose Acetate (CA) and Polysulfone (PS) to control the release of the biostimulants. SEM images showed that CA coating was porous and irregular in the inside and very uniform and tight like beehive while PS coating was the same in the inside and outside and not porous. Biostimulants release was found to be high in sea water compared to distilled water. The release of nitrate was higher compared to sulfate. In turbulent environment the release of bionutrients was 50% higher than static environment.

• Journal of the Korean Wood Science and Technology
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• v.43 no.3
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• pp.344-354
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• 2015

To investigate the effects of ionic liquid pretreatment on biomass, giant miscanthus was treated with 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) and 1-butyl-3-methylimidazolium acetate ([Bmim][OAc]) at three temperature conditions ($90^{\circ}C$, $110^{\circ}C$, and $130^{\circ}C$). As temperature condition increased, yield of the cellulose-rich product (CP) was reduced from 87.2% to 67.6%, while yield of the ionic liquid lignin (ILL) increased from 2.2% to 9.9%. Compared to the ILL, CP had lower carbon contents and higher oxygen contents. Enzymatic hydrolysis of CPs showed that conversion ratio of CP treated with [Emim][OAc] at $110^{\circ}C$ was 56.7%, the highest digestibility. Thermogravimetric analysis indicated that the maximum degradation rate decreased as temperature condition increased. In addition, maximum degradation temperature of ILL treated with [Emim][OAc] ranged from 274 to $279^{\circ}C$ which was lower than that of ILL treated with [Bmim][OAc]. Analytical date for ${\beta}$-O-4 linkage frequency in the ILL revealed that ${\beta}$-O-4 linkage frequency in the ILL decreased as the temperature rose. Furthermore, the highest S/G ratio of the ILL was determined to ca. 1.2 obtained from [Bmim][OAc] treatment at $110^{\circ}C$.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.56-60
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• 2018

There have been a lot of study to improve the performance of membrane filters as the removal of particulate matter has been of great interest due to the negative effects. Among the membrane fabrication techniques, the electrospinning technique is the most promising because it can produce uniform fibers ranging from nano to micrometer size. The electrospun membranes will greatly improve the filtration performance due to the high ratio of surface area to volume and the high porosity. In the present study, polystyrene (PS) and cellulose acetate (CA) polymers were used to produce the membranes with carbon nanotube (CNT), showing the filtration performances were improved with the optimal amounts of CNT.