• Polymer(Korea)
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• v.32 no.1
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• pp.63-69
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• 2008

The mechanical properties and morphologies of cellulose blends with two different additives were compared. Poly (vinyl alcohol) (PVA) of ethylene glycol (EG) were used as additives in the formation of cellulose blends through the solution blending. The properties of blends were varied with the additive content in the polymer matrix. The ultimate tensile strength and initial modulus of the cellulose blends were highest for a blend PVA content of 30 wt% and for a blend EG content of 10 wt%, respectively. Ternary blended systems of composition of cellulose/PVA (70/30=w/w)/EG were also prepared by the solution blending method with different EG contents. The mechanical properties of these systems were found to be optimal for EG contents of up to 40 wt%. The mechanical properties of the cellulose ternary blend films were superior to those of the cellulose binary blend films. The oxygen permeability transmission rate ($O_2TR$) monotonically decreased with increasing EG content in the ternary blend films. Overall, the mechanical properties of the cellulose blend films were found to be better than those of pure cellulose films.

• Membrane Journal
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• v.30 no.4
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• pp.252-259
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• 2020

Olefins are industrially important materials used for the synthesis of various petrochemicals. During the polymerization process, unreacted olefin monomers are discharged together with a large amount of nitrogen. For economic benefits, these olefin gases should be efficiently separated from nitrogen. In this study, a poly(glycidyl methacrylate-co-methyl methacrylate) (PGM) comb-like copolymer was synthesized and 4,4'-diaminoazobenzene (DAAB) was introduced to the copolymer to prepare a cross-linked membrane for C₃H₆/N₂ separation. PGM and DAAB were readily reacted at room temperature through an epoxide-amine reaction without additional thermal treatment. PGM-based membrane, which is a glassy polymer, showed a faster permeation of N₂ compared to C₃H₆. The pristine PGM membrane exhibited the N₂ permeability of 0.12 barrer and the high N₂/C₃H₆ selectivity of 32.4. As DAAB was introduced as a cross-linker, the thermal stability of the membrane was significantly improved, which was confirmed by TGA result. The N₂/C₃H₆ selectivity was decreased at 1 wt% of DAAB content, but the N₂ permeability increased by approximately 4.7 times. We analyzed N₂/C₃H₆ gas separation properties through a glassy polymer-based membrane, which has not been widely studied. Also, we proposed that thermal stability of the membrane can be greatly improved by the cross-linking method.

• Korean Journal of Materials Research
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• v.4 no.8
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• pp.952-957
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• 1994

Fe/Co and FeN/CoN multilayer films were prepared by using RF and DC magnetron sputter^ ing technique with Ar or a mixture of Ar and $N_{2}$ gas. Annealing treatment was carried out in a vacuum at temperatures between $100^{\circ}C$ and $500^{\circ}C$ for lhour. Saturation magnetization (MS) and coercivity (Hc) of Fe/Co mutilayer films were investigated as a function of Fe layer thickness and annealing temperature. Permeability ($\mu$) was also examined. Saturation magnetization of 1.8T and coercivity of 1.80e were obtained for the as-deposited Fe/Co($70 \AA /15 \AA$) multilayer film. The Coercivity(Hc) did not change from 1.8 Oe till the annealing temperature $250^{\circ}C$ and then increased rapidly at higher annealing temperatures above $300^{\circ}C$. Coercivity(Hc) measured for the as-deposited FeN/CoN multilayer film was 5 Oe. It decreased gradually with annealing up to $250^{\circ}C$, and then increased rapidly at higher tempera tures.

• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.469-473
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• 2018

When pure hydrogen was supplied to the stationary PEMFC generally using the reforming gas, its characteristics were compared with the vehicle PEMFC. The effect of varying the amount of hydrogen supply to the anode on the overall performance was compared. The variation of hydrogen supply in the range of 1.0~1.7 excess (stoi.) had little effect on the OCV of stationary and vehicle MEA (Membrane and Electrode Assembly). At 0.7 V, the current density of the stationary MEA was about 16% higher than that of the vehicle MEA. I-V performance, impedance, and LSV were measured with varying relative humidity. Both OCV and electrolyte membrane resistances decreased with increasing relative humidity. The hydrogen permeability of the stationary MEA was lower than that of the vehicle MEA, showing that the durability of the stationary membrane could be higher than that of the vehicle membrane.

• Journal of Fashion Business
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• v.16 no.3
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• pp.13-31
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• 2012

The purpose of the study was to analyze the work clothes' clothing comfort and wearer mobility of painting workers with the consideration of the work environment features in the machine and shipbuilding industries in South Korea. A questionnaire survey was conducted for the study, which consisted of questions on the clothing comfort and wearer mobility aspects of painting work clothes by clothes types and body parts. The work clothes' clothing comfort and wearer mobility levels were scaled in 5 points i.e. 1(: very tight/very uncomfortable) to 5(: very slack/very comfortable). The painting work environmental hazardous features were considered as high impact levels of workplace temperature, oxygen deficiency, organic solvent, toxic gas factors while metal fragment factor only impacts 'low' in the painting processes with the findings throughout this study. Since the painting work consisted of surface washing and the spray and touch-up painting processes, which was carried out in an outdoor work place, the painting work clothes should meet high performance of waterproofing from the painting material and air permeability specially in summer as well as thermal performance in winter. The subjects painting workers' assessment of the existing work clothes' clothing oppression was in the levels between 3 (i.e. moderate) and 4 (i.e. comfortable) in a range of 1 to 5 points. The existing painting work clothes' wearer mobility was evaluated 'very uncomfortable' in all work clothes parts, especially, armhole length, biacromial breadth, sleeve length of the jumper; and body rise, waist, hip, thigh and knee circumferences of the pants.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.1
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• pp.39-45
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• 2014

Various approaches have been tried to reduce the emission of carbon dioxide in paper industry. One of important approaches is to use PCC manufactured from emission gas as a filler. However, it was recognized that PCC is inferior to other fillers in the paper strength properties of view. Therefore, pretreatment of PCC with pulp powder was tried to mitigate the strength reduction of paper. Pretreatment of PCC with pulp powder improved the bulk(7.4~12.9%) and air permeability(24.8~42.98%), but there is no significant change in opacity. Tensile index, burst index and stiffness were decreased by the use of pretreated PCC with pulp powder. Anionic and cationic PAM were used as a additive for PCC pretreatment in order to improve strength properties. There was no significant change in bulk in all kinds of PAM used in this study. Most strength properties were improved by the pretreatment of PCC with the anionic and cationic PAM and pulp powder, although the opacity and stiffness were more or less decreased.

• Journal of Powder Materials
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• v.22 no.2
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• pp.100-104
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• 2015

The porous metals are known as relatively excellent characteristic such as large surface area, light, lower heat capacity, high toughness and permeability. The Fe-Cr-Al alloys have high corrosion resistance, heat resistance and chemical stability for high temperature applications. And then many researches are developed the Fe-Cr-Al porous metals for exhaust gas filter, hydrogen reformer catalyst support and chemical filter. In this study, the Fe-Cr-Al porous metals are developed with Fe-22Cr-6Al(wt) powder using powder compaction method. The mean size of Fe-22Cr-6Al(wt) powders is about $42.69{\mu}m$. In order to control pore size and porosity, Fe-Cr-Al powders are sintered at $1200{\sim}1450^{\circ}C$ and different sintering maintenance as 1~4 hours. The powders are pressed on disk shapes of 3 mm thickness using uniaxial press machine and sintered in high vacuum condition. The pore properties are evaluated using capillary flow porometer. As sintering temperature increased, relative density is increased from 73% to 96% and porosity, pore size are decreased from 27 to 3.3%, from 3.1 to $1.8{\mu}m$ respectively. When the sintering time is increased, the relative density is also increased from 76.5% to 84.7% and porosity, pore size are decreased from 23.5% to 15.3%, from 2.7 to $2.08{\mu}m$ respectively.

• Elastomers and Composites
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• v.46 no.2
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• pp.102-111
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• 2011

The innerliner for a tire has excellent impermeability, air retention and good flex properties. The innerliner offers a role to improve performance parameter, such as air retention and tire durability that is of praricular importance for commercial tires. In order to improve the gas barrier properties of a innerliner, most of the innerliner rubbers, such as a halogenated butyl rubber(HIIR), brominated poly(isobutylene-co-isoprene)(BIIR), brominated polyisobutylene-co-paramethylstyrene(BIMS) are used as nanocomposites with nano fillers such as silicates, graphite etc. Innerliners based on nanocomposites may allow gauge adjustments and permeability reductions with potential improvement in tire durability. This article discusses potential innerliner permeablity reduction and compounding parameters on the properties of nanocomposite based innerliners.

• Membrane Journal
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• v.11 no.2
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• pp.74-82
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• 2001

By using a phenomenological approach, model equations incorporating the resistance-in¬series concept were established to evaluate quantitatively concentration polarization in the boundary layer in feed adjacent to the membrane surface in the vapor permeation and separation of volatile organic compounds (VOCS)/$N_2$ mixture through po]y(dimethylsiloxane) (PDMS) membrane. The vapor permeations of various VOCS/$N_2$ mixtures through PDMS membrane were carried out at various feed flow rates. Chlorinated hydrocarbons, such as, methylene chloride, chlorofonn, 1,2-clichloroethane and 1,1,2-trichloroethane were used as organic vapor. By fitting the model equations to the experimental penneation data. the model parameters were detennined. respectively. Both the mass transfer coefficient of VOC across tbe boundary layer and concentration polarization modulus as a measure of the extent of concentration polarization were eitimated Quantitatively by the mooe1 equations with the determined model parameters. From the analysis on the detennined model parameters, the boundary layer resistance due to the concentration polarization of VOCs component was found to be more significant when the condensability of voe was greater. This study seeks to emphasize the importance of the boundary resistance on the vapor penneation of the vapor/gas mixtures with high permeability and high selectivity towards the minor component VOC.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.1
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• pp.81-87
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• 2010

In this paper, we have fabricated $SiO_2$ oxidation thin films by HDP-CVD(high density plasma-chemical vapor deposition) method for passivation layer or barrier layer of OLED(organic light emitting diode). We have control and estimate the deposition rate and relative index characteristics with process parameters and get optimized conditions. They are gas flow rate($SiH_4:O_2$=30:60[sccm]), 70 [mm] distance from source to substrate and no-bias. The WVTR(water vapor transmission rate) is 2.2 [$g/m^2$_day]. Therefore fabricated thin film can not be applied as passivation layer or barrier layer of OLED.