• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.1
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• pp.59-70
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• 1998

A steady-state molecular diffusion experiment was conducted to evaluate the water vapor proof properties of paper Handsheets prepared from unbleached Itraft pulps(UKP) and old newspapers(ONP) and four different types of polymer-laminated white duplex board were tested under appropriate standard conditions. The diffusivity was determined on the basis of the Fickean first law. Results obtained from this study can be summarized as follows ; 1. The diffusivity data for handsheets showed about $10^{-5}cm^2/min$. whereas polymer-laminated paperboards had remarkably improved water-vapor resistance with about $10^3 to 10^4$ times lower diffusivity : 2. Sheet basis weight, wet-swelling and sizing degree had little influence on the diffusivity of paper; 3 Linear relationship existed between sheet density and diffusivity, and, 4. Highly sfgnificant linear relationship could be observed between diffusivity and Darcy s gas permeability. Results indicate that diffusivity, an intrinsic property of paper, can provide a valuable information for precise evaluation and improved quality control of water-vapor proof properties of paper.

• Membrane Journal
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• v.18 no.3
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• pp.256-259
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• 2008

In this study, graphite or zeolite 4A was mixed with poly(acrylonitrile-butadiene-strene) (ABS) to make hybrid films, and permeation characteristics of air and water vapor through these films were investigated. In all cases, gas permeabilities of hybrid films were lower than that of pure ABS films. The permeability decrease of oxygen was slightly larger than that of nitrogen, resulting in the little decrease of $O_2/N_2$ selectivity. In addition, the water vapor transfer rates (WVTR) of hybrid films were about half of ABS film's. The decrease of permeabilities may be owing to the increase of tortuosity for diffusion in hybrid films.

• Journal of the Korean Society of Clothing and Textiles
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• v.20 no.1
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• pp.228-238
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• 1996

The purpose of this study was to evaluate the effect of chacteristics of knit fabrics on the microclimate of the skin simulating system. To determine the effect of characteristics of knit fabrics, vapor state of sweat pulse was simulated in the closed system. Different contents of fibers such as cotton, wool and polyester with different yarn size and knit types were chosen for specimens. The changes of humidity and temperature of air layer in the simulated systems were measured. Buffering indices, $K_d$ and $\beta_r$, were determined by considering $\alpha_p, \DeltaP_{max}, t_{max}, and tan\beta$. Physical properties of knit fabrics such as thickness, porosity, air resistance and moisture vapor transport were measured. Results showed that vapor pressure of wool was lower than cotton or polyester This was attributed to the hydrophilicity of wool which absorbed moisture rather quickly and retained in the knit fabric. The time to decrease vapor pressure was faster for polyester than cotton or wool. As a result, $K_d$ was in the order of wool> polye, item> cotton. $\beta_r$ of wool was rower than cotton or polyester due to its lowers porosity and slower desorption rate. For the yarn size, $K_d$ was in the order of 80's> 60's> 30's; thinner and lighter yarn showed better water vapor transport property. For knit type, buffering capacity of single jersey was better than interlock knit fabric. Statistical analysis showed that the air permeability was the most influential factor far the water vapor transport properties.

• Journal of Ginseng Research
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• v.25 no.1
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• pp.45-52
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• 2001

The storage stability of fresh ginseng packaged individually in a soft film bag was more enhanced as the soft film with lower oxygen permeability was used, while the optimum water vapor permeability for enhancing the storage stability of fresh ginseng was estimated 3.5 g/m$^2$$.$day$.$90% RH when using the soft film with low oxygen permeability of 3.6∼5.4 cc/m$^2$$.$day$.$atm. The storage stability of the individually packaged fresh ginseng was also enhanced when the soft film bag was filled with carbon dioxide-oxygen-nitrogen (25:5:70) miked gas but the vacuum packaging exhibited little effect for the enhancement of storage stability of the fresh ginseng.

• Membrane Journal
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• v.17 no.2
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• pp.140-145
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• 2007

In this study, 3-(trihydroxysilyl)-1-propanesulfonic acid (THS-PSA) was added to poly(vinyl alcohol) (PVA) membranes crosslinked with poly(styrene sulfonic acid-co-maleic acid) (PSSA_MA) to improve the separation characteristics toward water vapors in the air. The prepared membranes varying both PSSA_MA and THS-PSA amounts were also synthesized at different cross linking temperatures. Then, in order to investigate the separation characteristics of the resulting membranes, the dynamic vapor sorption (DVS) and vapor permeation experiments were carried out. The increase of cross-linking temperature showed longer time to reach the equilibrium sorption state from the dynamic vapor sorption experiments. PVA/PSSA_MA (3%)/THA-PSA(7%) prepared at $120^{\circ}C$ gave the highest permeability of 480 barrer at $35^{\circ}C$.

• Textile Coloration and Finishing
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• v.25 no.4
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• pp.279-286
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• 2013

Application properties of ultra light weight silica aerogel toward polyurethane membranes were investigated. From the results of pre-milling process of the silica aerogel, the solvent for dispersion of the aerogel was determined for methyl ethyl ketone and its content in the solvent was determined by 30%. Using this aerogel dispersion, the polyurethane membranes were prepared according to the mixing amount of silica aerogel and various properties of the membranes were investigated. As results, the optimum mixing amount of silica aerogel inside polyurethane membranes was decided at 11%, because the improvement of light weight property, air permeability, and moisture vapor permeability were improved upto 11% of silica aerogel content, maintaining the water penetration resistance almost unchanged.

• The Journal of the Korean dental association
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• v.11 no.3
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• pp.185-189
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• 1973

Dental amalgam in the clinic practice of dentistry is one of the most important materials. Mercury, one of the component of this alloy, is emitted in the form of vapor after filling as long as 5 days Silver particles penetrate into the dentine deeply along the tubles underneath cavity floor. To determine the permeability of mercury in the teeth following experiments were performed. Class 5 cavities total 40 from 10 dogs were prepared on upper and lower canines and amalgam alloys which contain about 10uCi of radioactive mercury were inserted. The animals were sacrificed 7 days after the experiments and the teeth were decalcified, sectioned and autoradiographed by means of emulsion and stained by H & E. Following are the results obtained from this experiments. 1. Blackened silver grains were found along the dentinal tubules underneath the cavity floor. Beyond the border of dentine and pulp chamber grains were seen in odontoblastic layer (Fig. 1, 2, 3, 4) 2. Underneath the odontoblastic layer, the pulp tissue showed almost normal appearance except slight dilatation of blood vessel.

• Journal of the Korean Ceramic Society
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• v.30 no.8
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• pp.678-684
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• 1993

Alumina composite membranes were prepared by chemical vapor deposition and evaporation-oxidation process. For CVD process, deposition was carried out using aluminum-tri-isopropoxide at 35$0^{\circ}C$, 2 torr by heterogeneous reaction, and for evaporation-oxidation process, alumina composite membranes were prepared by evaporation of aluminum and dry oxidation at 80$0^{\circ}C$. As deposition time increases, water flux and N2 gas permeability of the composite membranes prepared by both processes were reduced. Applying gas permeation model, permeability and cracking possibility of top layer were evaluated.

• Fashion & Textile Research Journal
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• v.1 no.3
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• pp.259-263
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• 1999

This study was carried out to investigate the changes of thermal properties such as warmth retaining and contact warm/cool feeling of commercial dress shirts by repeated washing and drying by sun and dryer. Three kinds of fabrics such as cotton 100%, cotton/polyester 80/20% and polyester 100% were repeatedly washed and dried, and then used as specimen. Thermo Labo II type was employed to measure the thermal properties. At the same time, structural properties such as thickness, weight, bulk density, porosity, moisture vapor permeability and air permeability were analysed.

• Journal of the Korean Society of Clothing and Textiles
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• v.20 no.6
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• pp.1071-1083
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• 1996

This study was carried out to obtain some fundamental data for designing thermally comfortable Korean folk clothes (KFC) which were classified into 4 groups according to seasons and materials. It was conducted to find the relationship among structural, thermal, and moisture transfer properties, and then the properties of heat and mositure transfer while changing thickness of air layer of selected similar fabrics with various thickness were examined. The summarized results of this study were as follows ; 1. The relationship between the structrual and thermal properties showed high positive correlation with thickness SE thermal insulation value (TIV), porosity & TIV. 2. The relationship between the structural and mositure transfer properties showed high negative correlation with thickness & moisture vapor permeability (Mp), porosity & Mp respectively. 3. The relationship between the heat and moisture transfer properites showed high negative correlation with qmax, air permeability (Ap), Mp & TIV while showed high positive with Ap & Mp respectively. 4. Resistance to dry heat transfer according to thickness of air layer for KFC was increassed rapidly up to 2 mm and above this increasing rate was reduced. Resistance to evaporative heat transfer was remarkable changes in 6∼8 mm but slowly in 6∼8 man. 5. Mioisture permeability index (i) according to thickness of air layer for KFC showed the greatest value at 2 mm but had not difference between groups according to thickness.