• Membrane Journal
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• v.27 no.2
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• pp.154-166
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• 2017

Polymeric films for gas barrier applications such as food packaging and electronic devices have attracted great interest due to their cheap, light and easy processability among gas barrier materials. Especially in electronic devices, extremely low gas permeance is necessary for maintaining the device performance. However, current polymeric barrier films still suffer from relatively high gas permeance than other materials. Therefore, there have been strong needs to enhance the gas barrier performance of polymeric barrier films while keep their own advantages. Recently, graphene is highlighted as a 2D-layered material for gas barrier applications. However, owing to the poor workability and difficulty to produce in engineering scale, graphene oxide (GO) is on the rise. GO consists of oxygen-containing functional groups on surface with intrinsic 2D-layered structure and high aspect ratio, and it can be well-dispersed in aqueous polar solvents like water, resulting in scalable mass production. Here, we prepared GO incorporated polyimide (PI) nanocomposites. PI is widely used barrier polymer with high mechanical strength and thermal and chemical stability. We demonstrated that PI/GO nanocomposites could perform as a gas barrier. Furthermore, surfactants (Triton X-100 (TX) and Sodium deoxycholate (SDC)) are introduced to enhance the gas barrier performance by improving the degree of dispersion of GO in PI matrix. As a result, TX enhanced the gas barrier performance of PI/GO nanocomposites which is similar to predicted value. This finding will provide new insight to polymer nanocomposites for gas barrier applications.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.23 no.3
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• pp.92-96
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• 1997

Nowadays, ceramides have been found to be an important component in the outermost layer of the skin - the stratum corneum. It is undersrood that ceramides play an important role in structure and maintenance of the interellular lipid lamella structure in the SC layer. Thus, many efforts have been made by the cosmetics and pharmaceutical industries to get human skin-identical ceramides or pseudoceramides which show similar performance with natural ceramides. The purpose of our study was to systhesize new pseudoceramides via an effective and economical systhetic pathway and to show their performance of skin restoratio. Four kinds of the new pseudoceramides were synthesized by the reaction of alcoholic amine and alkyl ketene dimer. First of all, PC-4 and PC-5 were synthesized by the reaction of 3-amino-1,2-propanidiol and serinol with alkyl ketene dimer respectively. After that, PC-4R and PC-5R were produced by changign kitone group at $\beta$-position to amide bond of above synthesized PC-4 and PC-5 into hydroxyl group using NaBH4 respectively. Their expected structures were conformed by the NMR, IR spectra, and elemental analysis. A study to show the restoration effectiveness was performed in which human skin was pretreated with high concentration of SDS surfactant solution. Using 0.5% solution of above synthesized pseudoceramides, there was the significantly faster restoration of the damaged than that of placebe itself treatment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.1
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• pp.62-67
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• 2005

Recently, polymer insulators that are used for high voltage applications have some advantages such as light weight, small size, vandalism resistance, hydrophobicity and easy making process. During outdoor service of polymer insulators, the surface of the insulating material is frequently subjected to moisture and contamination that lead to dry band arcing. Their tracking resistance, erosion resistance, end sealing and shed design are very important because dry band arcing causes degradation of polymer surface. Aging test to estimate life property of polymer insulator is executed through several international standard such as IEC 61109 and CEA tracking wheel test, but is not getting clear conclusion yet. There are two methods in the diagnosis method of polymer insulator such as off-line and on-line. The diagnosis methods in off-line are external condition analysis by the eye, contaminant analysis on surface, surface analysis, pollution withstand voltage test, power frequency flashover voltage test, lightning impulse flashover test, tensile fracture load test and flexural load test. Polymer material is also investigated it's tracking resistance by adding surface active agent in IEC 587. In this paper, the tracking performance of polymer insulator with salt solution which is added surface active agent. The diagnosis of insulator sample has been analyzed by leakage current and visual examination, STRI guide and thermal image camera.

• Korean Journal of Food Science and Technology
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• v.29 no.1
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• pp.26-31
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• 1997

Bee venom (Apis mellifera) phospholipase $A_2$ solubilized in reversed micelles containing small amount of water stabilized by surfactant could catalyze the hydrolysis of dipalmitoyl phosphatidylcholine (DPPC). A sensitive and simple high performance liquid chromatographic (HPLC) methodology of phospholipase $A_2$ assay for the hydrolysis of DPPC was developed. Kinetic analysis of the phospholipase $A_2$-catalyzed reaction was found to be possible in reversed micelles. Among the surfactants and organic solvents tested, aerosol-OT and isooctane were most effective for the hydrolysis of DPPC in reversed micelles. Optimal temperature, optimal pH, $K_{m,app.},\;V_{max.,app.}$ and activation energy were determined to be $35{\sim}40^{\circ}C$, 7.0, 8.73 mM, 2.83 units/㎎ protein and 12.31 kcal/mole, respectively. The hydrolysis activity was dependent on water content and maximum activity was obtained at R value (=[water]/[aerosol-OT]) of 10.0.

• Biomolecules & Therapeutics
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• v.4 no.4
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• pp.419-427
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• 1996

To solubilize practically insoluble biphenyl dimethyl dicarboxylate (DDB), which has been used for the treatment of chronic hepatitis as tablets or hard capsules, the solubilities of DDB in various hydrophilic, oily and hydrocarbon vehicles, and aqueous surfactant solutions were measured by high performance liquid chromatography. It was found that, among the vehicles studied, polyethylene glycol (PEG) 300 revealed the best solvency, and the solubility reached 17.6 mg/ml at 37$^{\circ}C$. The addition of glycyrrhizic acid ammonium salt (GAA) to DDB-PEG 300 solution (5-20 mg/g) inhibited the formation of precipitates, and at the concentration of 10 mg/g, any precipitaction was not observed even after 2 years at 4$^{\circ}C$. Furthermore, GAA markedly enhanced the permeation of DDB through the rabbit duodenal mucosa in a concentration dependent manner. The addition of copolyvidone (ca. 1.0%) to DDB-GAA-PEG 300 system (1 : 0.5 97.5 w/w) was most effective in preventing the considerable precipitation of DDB-PEG 300 solution (7.5 mg/750 mg) when mixed with water of 300-900 ml at 37$^{\circ}C$. GAA showed a synergistic effect in the prevention of precipitate formation. This finding suggests that this DDB formulation may form less precipitation when DDB soft capsules disintegrate and diffuse into the gastrointestinal fluid, resulting in improving the bioavailability Dissolution rate of DDB (7.5 mg) from sort elastic capsules of DDB-GAA-PEG 300 system was rapid. The supersaturation state was maintained for 2 hr at the concentration of 7.35$\pm$3.3 mg in 900 ml of water without precipitation. The total amount of DDB dissolved from this new formulation was 5.3 and 6.1 times higher, when compared to marketed DDB tablets (25 mg) and capsules (7.5 mg), respectively.

• Journal of Microbiology and Biotechnology
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• v.10 no.3
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• pp.349-354
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• 2000

Abstract A facultative alkalophilic gram-negative Vibrio metschnikovii strain RH530, isolated from the wastewater, produced several alkaline proteases (VAP) including six alkaline serine proteases and a metalloprotease. From this strain, high yielding YAP mutants were isolated by NTG treatment. The isolated mutant KS1 showed nine times more activity than the wild-type after optimization of the culture media. The production was regulated by catabolite repression when glucose was added to the medium. The effects of several organic nitrogen sources on the production of the YAP were investigated to avoid catabolite repression. The combination of 4% wheat gluten meal (WGM), 1.5% cotton seed flour (eSF), and 5% soybean meal (SBM) resulted in the best production when supplemented with 1% NaCl. The YAP showed a resistance to surfactants such as $sodium-{\alpha}-olefin$ sulfonate (AOS), polyoxy ethylene oxide (POE), and sodium dodecyl sulfate (SDS), yet not to linear alkylbenzene sulfonate (LAS). However, the activity of the YAP was restored completely when incubated with LAS in the presence of POE or $Na_2SO_4$. The YAP was stable in a liquid laundry detergent containing 6.6% SLES (sodium lauryl ether sulfate), 6.6% LAS, 19.8% POE, and stabilizing agents for more than two weeks at $40^{\circ}C$, but the stability was sharply decreased even after 1 day when incubated at $60^{\circ}C$. A washing performance test with the YAP exhibited it to be a good washing power by showing 51 % and 60% activity at $25^{\circ}C{\;}and{\;}40^{\circ}C$, respectively, thereby indicating that the YAP also has a good detergency at a low temperature. All the results suggest that the YAP produced from the mutant strain KSI has suitable properties for use in laundry detergents.rgents.

• Journal of the Society of Disaster Information
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• v.8 no.3
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• pp.223-233
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• 2012

Steel fiber is high stiffness and large weight. So, Pumping hose to rupture of the safety management is difficult. Steel fiber caused by corrosion of the deterioration of durability and high-rebound losses are needed for the improvements. Thus, the revised regulations in 2009 by a steel fiber to reinforce other materials is possible. Variety of fiber reinforcement material for concrete review of applicability is needed. Steel fiber strength than the other fibers is large and by the geometry of the fibers are attached to improve performance. However, compared to steel fiber organic fibers and low modulus of elasticity and tensile strength of fiber and agglomeration occurs in the concrete to be used as reinforcement material is difficult. In this regard, the present study as a single object in the micro-fiber bouquet sharp entanglement through make muck attach surface area, distributed fibers from surfactant of the surface enhanced polyamide fibers, steel fiber and PP fiber reinforced concrete by comparing the scene to provide a basis for the use.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.708-715
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• 2017

Recently, in order to meet the stricter emission regulations, the proportion of after-treatments for vehicles and vessels has been increasing gradually. The objective of this study is to investigate the improvement of $CH_4$ reduction ability of natural gas oxidation catalyst (NGOC), which reduces toxic gases emitted from CNG buses. Thirteen NGOCs were prepared, and the conversion performance of noxious gases according to the type of supports, the loading amount of noble metal, and surfactant and aging were determined. Support Zeolite supported on No. 3 $NGOC(1Pt-1Pd-3MgO-3CeO_2/(46TiO_2+23Al_2O_3+23Zeolite)$ is an anionic alkali metal/earth metal component that improved the oxidation reactivity between CO and NO and noble metal dispersion, and thus enhanced the $CH_4$ reduction ability. As the loading amount of Pd, a noble metal with a high selectivity to $CH_4$, was increased, the number of reaction sites was increased and the ability to reduce $CH_4$ was improved. No. 11 $NGOC(1Pt-1Pd-3MgO-3CeO_2/(Z20+Al80)$(pH=8.5), to which nitrate surfactant had been added, exhibited well dispersed catalyst particles with no agglomeration and improved the $CH_4$ reduction ability by 5-15%. The $NGOC(2Pt-2Pd-3Cr-3MgO/90Al_2O_3)$(48h aging), which was mildly thermal aged for 48h, increased the $CH_4$ reduction ability to about 10% or less as compared with No. 12 NGOC(Fresh).

• Toxicological Research
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• v.20 no.3
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• pp.195-203
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• 2004

4-Tert-Octylphenol (OP) is a surfactant additive widely used in the manufacture of a variety of detergents and plastic products. OP can disrupt endocrine function in humans and animals. This study was carried out to obtain toxicokinetic parameters of OP in male Sprague-Dawley (SD) rats. Male rats were administered with OP by single oral application of 200 mg/kg body weight. Blood, urine and tissues samples were taken at several time intervals after administration. Analysis of samples for OP was performed by column-switching high performance liquid chromatography (HPLC). In addition, we exam-ined tissue distribution and accumulation of OP after single oral application of 50, 100, and 200 mg/kg, single intravenous injection of 1, 5 and 10 mg/kg or daily application of 50 mg/kg for 14 consecutive days. After single oral administration of 200 mg/kg, Cmax of 213 $\pm$ 123 ng/ml was reached within the first 1.3 hr (Tmax) in the plasma. AUC was calculated for 1,333$\pm$484 ngㆍhr/ml. The final elimination half-life of plasma was longer than that of urine, but urinary clearance was lower than oral. A very small fraction of OP (Fe < 0.0017%) was excreted in urine within 24 hr. These results indicated that the major excretion route of OP was not urine. The mean maximal tissue distribution of OP was obserbed at 6 hr after treatment and slowly decreased time-dependently. High OP concentrations were detected in fat at 24 hr. The OP in fat was slowly released with longer elimination half-life and lower clearance than that of other tissues. OP was not accumulated in the liver following single oral application but 14-day oral treatments resulted in two-fold accumulation. It was probably due to the saturation of detoxification pathways. On the other hand, the mRNA expression of cytochrome P450 isoforms except CYP2C11 was not affected by OP at any dose. The expression of CYP2C11 mRNA decreased in a dose-dependent manner. This result suggests that OP changes expression of the male-specific cytochrome P450 isoforms in rat liver, and these changes are closely related to the toxic and estrogenic effect of OP.