• Macromolecular Research
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• v.15 no.1
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• pp.22-30
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• 2007

High water vapor permeable coating materials were prepared by blending aqueous poly(vinyl alcohol) (PVA) solution with waterborne polyurethane-urea (WBPU) dispersions synthesized by prepolymer mixing process. Stable WBPU/PVA dispersions were achieved at PVA content below 30 wt%. As the water soluble polymer PVA content increased, the number and density of total micro-pores (tunnel-like/isolated micro-pores) formed after the dissolution of PVA in water increased, and the water vapor permeability of coated Nylon fabric also increased significantly. Using WBPU/water soluble polymer PVA blends as a coating material and then dissolving PVA in water was confirmed to be an effective method to obtain prominent breathable fabrics.

• International Journal of Concrete Structures and Materials
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• v.2 no.2
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• pp.83-90
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• 2008

Permeability to vapor and water among other performances required for finishing materials is dealt with in this study. The relative moisture content of concrete coated/covered with a finishing material was experimentally investigated while changing the environmental conditions including temperature, relative humidity, and rainfall. An organic paint (water-based urethane), organic synthetic resin emulsion-type film coating (film coating E), and inorganic porcelain tiles were selected as the finishing materials. When compared from the aspect of vapor and water permeability, the vapor permeability and water permeability of water-based urethane were high and low, respectively; those of film coating E were high and high, respectively; and those of porcelain tiles were low and low, respectively. This means that the moisture state of concrete structures is governed not only by the environmental conditions but also by the performance of finishing materials. It is therefore of paramount importance to appropriately select a finishing material to address the specific deteriorative factors involved in the concrete structure to be finished.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.205-212
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• 1998

In this study, the effects of water vapor in inlet air on combustion efficiency, general performance, knock characteristics and emission gas concentration were investig- ated through the experiments of combustion and vibration analyses, emission gas analysis by changing water vapor quantity in inlet air with temperature and humidity auto control unit. With partial vapor pressure increase, the brake torque at wide open throttle status decreased and the average ignition delay angle increased, IMEP (indicated mean effective pressured using the integral and 3rd derivatives of filtered cylinder pressure as knock intensity, which matched well with the method of frequency power spectrum of block vibration signal. Water vapor in intake air had influence on the spark knock sensitivity. With the increase of water vapor content in intake air NOx emission was decreased and HC emission was increased.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.1
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• pp.61-71
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• 1999

The study aimed at the theoretical analysis of vapor sorption properties of, pp.rmaking fibers. Water vapor affinity and sorption thermodynamic properties of fiber constituents were evaluated based on Henry's law and Hildebrand's solubility theory. Theoretical equilibrium moisture content(ThEMC) on fiber surface was estimated using functional group contribution. Crystallinity of cellulose in fiber significantly controlled the water vapor solubility. Comparisons of the measured equilibrium moisture content data and the estimated ThEMC data coincidently suggested the fact that crystallinity of cellulose in fibers was around 60% to 70%. Carbohydrates constituents including amorphous cellulose and hemicellulose in fibers showed higher vapor solubility than lignin molecules. High correlation existed between ThEMC and vapor solubility as well as between ThEMC and solubility parameter. In the thermodynamic analysis on water-vapor sorption process in fibers, the sorption enthalpy increased as RH increased, whereas sorption entropy and free energy decreased with increasing RH.

• Atmosphere
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• v.18 no.4
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• pp.417-427
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• 2008

In this paper, we analyzed the physical and thermodynamic characteristics of fog by using the integrated water vapor (IWV) from Global Positioning System (GPS) networks and the regular observation data of meteorological stations in GPS sites. The cases of a radiation and an advection fog were selected as samples, the conversions of water substance from the water vapor to cloud water in fog were detected by the Bulk Water-Continuity Model, and the pattern analysis is adapted on GPS IWV, temperature, wind and relative humidity. Under the specific hypothesis (saturation and stable), GPS IWV could detect quantitatively the phase changing between the water vapor and cloud water content with condensation/evaporation during the formation and dissipation of fog. After it reaches to the saturation, the relative humidity can be a limited indicator for fog. However, GPS IWV can detect the status change of fog even after the saturation. It has indicated that GPS IWV could be a new observing technique for the processes of the fog formation and the dissipation.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1996.11a
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• pp.50-53
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• 1996

This paper reports the experimental results for the determination of the overall partition coefficient of VOCs in unsaturated soil, A chromatographic method was used for the determination of gaseous partition coefficients to natural soil under various water content conditions. The equilibrium vapor pressure of water over saturated salt solution was used to fix the relative humidity of the air and control the water content of the soil systems. The transport behavior was studied for dichloromethane, trichloroethane and dichlorobenzene pollutants, with log octanol-water partition coefficients(log $K_{ow}$ ) which range from 1.25 to 3.39, or water to soil partitioning which varies by 135 times; water solubility constants which vary by 3 times; and vapor pressures which range from 1 to 362 torr. Water content of the soil had a pronounced effect on the effective partition coefficient(between gas and soil + water stationary phase) as well as on the effective dispersion coefficient.

• Preventive Nutrition and Food Science
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• v.13 no.1
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• pp.28-32
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• 2008

Water vapor sorption by sodium alginate-based films may result in swelling and conformational changes in the molecular structure and affecting the water vapor barrier properties. Sodium alginate film specimens were dried in a vacuum freeze dryer and their moisture content was determined by an air-oven method. The water vapor absorption was determined at two different levels of water activities (0.727 and 0.995) and at three temperatures (10, 20, and $30^{\circ}C$), and kinetics were analyzed using a simple empirical model. Reasonably good straight lines were obtained with plotting of 1/($m-m_0$) vs 1/t. It was found that water vapor absorption kinetics of sodium alginate films were accurately described by a simple empirical model. The rate of water vapor sorption increased with increase in temperature and it showed temperature dependency following the Arrhenius equation. The activation energies varied from 49.18$\sim$149.55 kJ/mol depending on the relative humidity.

• Fibers and Polymers
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• v.3 no.4
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• pp.153-158
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• 2002

A series of waterborne polyurethanes (WBPU) were prepared from 4,4-dicyclohexylmethane diisocyanate ($H_{12}$MDI),2,2-bis(hydroxylmethyl) propionic acid (DMPA), othylenediarnine (EDA), triethylamine (TEA), and triblock glycol [TBG, ($\varepsilon$-caprolactone)$_{4.5}$-poly(tetramethylene ether) glycol (MW= 2000)-($\varepsilon$-caprolactone)$_{4.5}$: $(CL)_{4.5}$-PTMG-$(CL)_{4.5}$, MW=3000] as a soft segment. Two melting peaks of TBG at about 14$^{\circ}C$ and 38$^{\circ}C$ were observed indicating the presence of two different crystalline domains composed of CL and PTMG dominant component. The effect of soft segment content (60-75 wt%) on the colloidal properties of dispersion, and thermal and mechanical properties of WBPU films, the water vapor permeability (WVP) and water resistance (WR) of WBPU-coated Nylon fabrics, and the adhesive strength of WBPU- coated layer and Nylon fabrics was investigated. As soft segment contents increased, the water vapor permeability of WBPU- coated Nylon fabrics increased from 3615 to 4502 g/$m^2$day, however, the water resistances decreased from 1300 to 500 mm$H_2$O.O.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.710-714
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• 2009

In this study, we analyzed the desulfurization performance of Zn-based dry sorbents according to the reducing power, water vapor content and $H_2S$ inlet concentration of coal gas in a batch-type fluidized-bed reactor. We used three different coal gas composition with different reducing power such as KRW air-blown coal gas, Shell oxygenblown coal gas and IAE coal gas. The experiments were performed by changing the inlet concentration of water vapor and $H_2S$ in a coal gas. Water vapor content was varied from 5% to 30% and $H_2S$ inlet concentration from 0.5% to 2.0%. As both the water vapor content and $H_2S$ inlet concentration increased, desulfurization performance of Zn-based sorbents decreased regardless of the reducing power of the coal gas. The minimum desuflurization performance was, however, above 99.5% for all experimental conditions, which implied that Zn-based dry sorbents could be used to remove $H_2S$ up to 99%.

• Journal of the Korean Society of Tobacco Science
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• v.6 no.1
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• pp.33-37
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• 1984

The net enthalpy changes for the water desorption of sun-cured tobacco have been studied. In order to compare the values of net enthalpy changes for the samples at the same moisture contents, correlation analyses have been performed. The results are summarizing as followings : 1 . As temperature and water vapor pressure increased, equlibrium moisture content were approaching to the saturated vapor pressure of water. 2. The values of 1nP against the reciprocal of absolute temperature were linear for the water desorption of samples. 3. Multiple regression was analyzed to calculate the values of 1nP at the same moisture content. The significance of $x^2$-test for the multiple regression was 0.5%. 4. The values of net enthalpy changes for Basma were greater than those of Sohyang at the same moisture content.