• Journal of the Korean Electrochemical Society
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• v.10 no.2
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• pp.82-87
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• 2007

New porous separators based on non-polyolefin materials including the blend of poly (vinyl chloride) (PVC)/poly (vinylidene fluoride-co-hexafluoropropylene) (P(VdF-co-HFP)/poly(methyl methacrylate) (PMMA), and the porous separator based on poly (vinylidene fluoride) (PVdF) were prepared by phase inversion method. The porosity and morphology were controlled with phase inversion rate, which is governed by the relative content of non-solvent and solvent in coagulation bath. To enhance tensile strength, the solvent pre-evaporation and uni-axial stretching processes were applied. The ionic conductivity was increased with increasing stretching ratio, and tensile strength was increased with increasing solvent pre-evaporation time and stretching ratio. The 200% stretched PVdF separator showed 56 MPa of tensile strength, and the ionic conductivity of the stretched PVdF separator was $8.6{\times}10^{-4}\;S\;cm^{-1}\;at\;25^{\circ}C$.

• Fashion & Textile Research Journal
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• v.14 no.3
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• pp.472-477
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• 2012

The conditions of wet spinning were considered in order to prepare the fine denier of acrylic fiber. Polyacrylonitrile copolymer was synthesized by the copolymerization of acrylonitrile (AN) and methyl acrylate (MA) initiated by an aqueous sulfite-chlorate redox system. Acrylic fiber was manufactured through wet-spinning in a dimethyl formamide (DMF) system. The conditions of wet-spinning were investigated by i-value, spinning speed, diameter of spinneret, draw ratio, water content of spinning dope and morphology of protofiber. The physical properties of fibers were investigated by Instron. In this experiment, the minimum i-value decreased with the decreasing spinneret diameter, an increased spinning speed, and an increased coagulation bath (CBC) concentration. The maximum draw ratio increased with an increased CBC. The optimum CBC and water content of the spinning dope were 60%-65% and 3.5%, respectively. The tenacity at the breaking point increased with a decreased fineness of fiber. The elongation at breaking point was almost the same value as a function of the fineness of fiber.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1649-1651
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• 2000

Optical properties of $Cd_{1-x}Zn_{x}S$ films deposited by :chemical bath deposition(CBD), which is a very attractive method for low-cost and large-area solar cells, are presented, Especially, in order to control more effectively the zinc component of the films, zinc acetate, which used as the zinc source, mixed in reaction solution after preheating and the pH of the reaction solution decreased with increasing the concentration of zinc acetate. The films prepared after preheating and pH control had larger zinc component and higher optical band gap. As the more zinc substituted for Cd in the films, the optical transmittance improved, while the absorption edge shifts to a shorter wavelength and the optical band gap increased. The photo conductivity of the films was larger than the dark conductivity, while the ratio of those increased with increasing the mole ratio of zinc acetate.

• KSBB Journal
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• v.8 no.3
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• pp.282-286
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• 1993

A bath foam separator has been used to separate yeast cells from their culture broth without the use of any surface-active agents. The cell separation ratio was improved in proportion to a separator level and nitrogen flow rates. Percentage of yeast removal after 3 minutes of operation was more than 90. The cell separation ratio was also improved by the addition of 0.2g/l $CaCl_2$.

• Journal of the Korean institute of surface engineering
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• v.53 no.6
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• pp.312-321
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• 2020

Morphology of porous cobalt electro-deposits was systematically investigated as functions of cobalt precursors in the plating bath and applied cathodic current density with a special focus on cobalt nano-rod formation. It was proved that the concentration of cobalt precursor plays little effect on the morphology of cobalt electro-deposits at relatively low plating current density while it significantly affects the morphology with increasing plating current density. Such a dependence was discussed in terms of the kinetics of two competitive reactions of cobalt reduction and hydrogen evolution. Cobalt nano-rod structure was created at specific ranges of cobalt precursor content and applied cathodic current density, and its diameter and length varied with plating time without notable formation of side branches which is usually found during dendrite formation. Specifically, the nano-rod length was preferentially increased in relative short plating time (<15 s), resulting in higher aspect ratio of nano-rod with plating time. Whereas, both the nano-rod length and diameter were increased nearly at the same level in a prolonged plating time, making the aspect ratio unchanged. From the analysis of crystal structure, it was confirmed that the cobalt nano-rod preferentially grew in the form of single crystal on a dense poly-crystalline cobalt thin film initially formed on the substrate.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2008.04a
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• pp.156-158
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• 2008

Hollow fibers have been used in rather different fields of general textile use and in special-purpose products because of their unique structure. Hollow fibers have profitable properties for some applications because of their large surface/volume ratio. In this paper, dyeing properties of nylon hollow fiber were investigated. Nylon regular fiber and hollow fiber were used in the dyeing experiment. The samples were dyed with three kinds of acid dyes. Effects of dyeing temperature, pH of the dye bath, and dye concentration on dyeing properties were examined.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2008.04a
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• pp.117-119
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• 2008

This study was investigated for the dyeing properties of silk fabrics with Annatto Extract. The dye stuff was extracted by distilled water at 60$^{\circ}C$, 10minutes, 100:1 of bath ratio. The highest K/S value was showed at 25% dye concentration, 60minutes of dyed time at 50$^{\circ}C$ in the temperature. The post mordant conditions were better than that of pre mordant, especially post-Fe mordant showed highest K/S value. The laundering fastness was relatively good by Cu-mordant. Drying cleaning fastness appeared 4-5 grades.

• Journal of the Korean Home Economics Association
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• v.40 no.8
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• pp.99-105
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• 2002

This study was to investigate the natural dyeing materials in domestic, trials to detect new Inula Britannica. An appropriate dyeing condition ;was bath ratio 1:20, 50% (o.w.f.)conc., $80^{\circ}C$, 50min. The K/S values of silk fabric was the most efficient for the pre-mordanting method. The value of dyed fabric was mostly dark, for the mordanting, the chroma was best clear when using the Cr-mordant, color difference was distinct when using the Fe-mordant. The antimicrobiality of Inula Britannica itself appeared as a 6mm halo zone, dyed fabric was excellent with result of over 90% in mordant. In the case of dye fastness, the drycleaning and wet cleaning fastness was excellent, rubbing and perspiration fastness was improved, and light fastness was over level 2.

• Textile Coloration and Finishing
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• v.14 no.6
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• pp.328-334
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• 2002

Nylon 6 staple ultramicrofiber(UMF, 0.074) and regular staple fiber (Regular, 2.0d) were annealed at In, 130, 160 and $180^\circ{C}$ under tension free for 10 min and U min. The treated fibers were dyed with Acid Red 18 and Blue n3. They were adjusted at PH 5.0 of dye bath in buffer solution of $CH_3COOH/CH_3/COONa(0.1mo1/1)$. Liquor ratio was kept at 1000:1. Dyeing rate of UMF annealed at $100^\circ{C}$ was decreased, but was increased for regular nylon. Also dye equilibrium of UMF at $100^\circ{C}$ was increased for Acid Red 18, but was decreased for Acid Blue 83. The intensities of X-ray diffraction peaks of UMF increased with increasing annealing temperature. Also the crystallinity of heat-sotted fibers by DSC thermogram was well agreed with the tendency of density Amino end group, moisture regain and water absorbency were decreased with increasing annealing temperature.

• Journal of the Korean Ceramic Society
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• v.30 no.5
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• pp.411-419
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• 1993

A process for the preparation of cobalt oxide powders was developed by the evaporaton of emulsion containing cobalt. The characteristics of powders were examined by means of DTA, X-ray diffracton, SEM, PSA. Cobalt oxide powders were produced by evaporating the emulsion prepared by mixing cobalt sulfate solution and organic phase consisted of kerosene, Span 80 and D2EHPA in the kerosene bath at 16$0^{\circ}C$, then the precursor obtained was calcined at 100$0^{\circ}C$. As the concentration of cobalt ions in the aqueous solution, Span 80 and the stirring speed increased, the mean size of cobalt oxide powders decreased and the size distribution was improved. At the volume ratio of one of the aqueous to organic phase, the finest mean size and the optimum size distribution was obtained. On the other hand the concentration of D2EHPA and liquid paraffin had little effect on the mean size as well as on the size distribution of powders.