• Journal of the Korean Wood Science and Technology
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• v.49 no.5
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• pp.471-481
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• 2021

This study investigated the hygroscopicity and UV deterioration characteristics of 3 domestic and 4 imported woods using natural oil, stain, and varnish paints. In terms of hygroscopicity, it was found that the hygroscopicity of the painted wood was lower than that of the unpainted wood, and that as the number of coatings increased, the hygroscopicity decreased. In terms of anti-absorption, oil-based chemical paints showed higher resistance than water-based paints, and natural oils showed results comparable to oil-based paints. As for the UV deterioration, the amount of color change of the painted wood was lower than that of the unpainted wood, and there was no significant difference according to the number of times of painting. The amount of color change was found to be low in oil-based paints and hardwoods. Through this study, we confirmed effective moisture blocking and small color changes during painting using paints, and it is believed that wood can be protected from internal and external defects through selective and efficient painting based on data for excellent painting performance.

• Journal of ILASS-Korea
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• v.3 no.3
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• pp.14-22
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• 1998

The growth by steam condensation of an hygroscopic aerosol is investigated using the condensation rate model which has been derived from the mass and heat transfer equations. The present model accounts for both the solute and Kelvin effects. When the hygroscopicity is considered, condensation can occur on hygroscopic seed particles even under subsaturated steam conditions. This study focuses on the effect of hygroscopicity on the evolution of the particle size distribution and decay of the total aerosol concentration. It is found that hygroscopicity causes the particle size distribution to rapidly move upward even in a very short time, resulting in substantially higher decay of the total aerosol concentration than the case without considering hygroscopicity.

• Journal of Electrochemical Science and Technology
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• v.12 no.4
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• pp.387-397
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• 2021

Deep eutectic solvents have been established as feasible metal electroplating solvent alternatives over traditional toxic aqueous plating baths. However, water, either added intentionally or unintentionally, can significantly influence the solvent's physical properties and performance, thereby hindering its industry application. In this study, the hygroscopicity, or the ability to absorb moisture from the environment, of synthesized ethaline (1:2 choline chloride:ethylene glycol) was investigated. The kinematic viscosity, electrical conductivity, electrochemical window, and water content of ethaline were monitored over a 2-week period. Karl Fischer titration tests showed that ethaline exposed to the atmosphere displayed significant hygroscopicity compared to its unexposed counterpart. ¹H NMR spectroscopy revealed that water vapor was readily absorbed at the surface due to the hydrophilic groups present in the ethaline molecule. Water uptake resulted in the decrease in viscosity, increase in electrical conductivity and narrowing of the electrochemical window of ethaline. Solution heating at 100℃ removed the absorbed moisture and allowed the recovery of the solvent's initial properties.

• Journal of the Korea Furniture Society
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• v.20 no.6
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• pp.560-565
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• 2009

It is known that heat treatment decreases the hygroscopicity of wood. Thus heat-treated wood is good for outdoor construction due to its improved dimensional stability. This study is to investigate the hygroscopicity and discoloration of spruce and birch boards heat-treated above $190^{\circ}C$. The equilibrium moisture contents (EMCs) at all relative humidities decreased with the increase of heat treatment temperature and/or time for both spruce and birch. It was revealed that heat-treatment temperature affected more on the hygroscopicity thaan heat-treatment time. The average basic densities decreased for the spruce specimens, but increased for the birch specimens with an increase of the treatment time and/or temperature. The same heat treatment condition (190-8) made the birch specimens darker than the spruce specimens.

• Journal of the Korea Furniture Society
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• v.27 no.4
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• pp.302-308
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• 2016

It has been known that acetylation improves the dimensional stability of wood. Liquid phase acetylation is more popular than gas-phase acetylation for the effectiveness of weight gain of wood. In this study the specimens of domestic red and Korean pines are acetylated in liquid phase and their physical properties, such as density, bending strength, anti-hygroscopicity etc., are analyzed. Acetylation increases the average weights and volume of larch specimens by 11.4% and 3.4%, respectively, and their average oven-dry densities are increased by $0.03g/cm^3$. Acetylation does not influence on Modulus of Rupture (MOR) and Modulus of Elasticity (MOE). The average Percentage Reduction in Hygroscopicity (PRH) and average Percentage Reduction in Water soaking (PRW) of larch specimens are respectively 20.2% and 20.8%. Thus it can be concluded that acetylation improves the dimensional stability of larch specimens.

• Journal of the Korea Furniture Society
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• v.19 no.4
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• pp.229-234
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• 2008

In a previous study, it was revealed that three major softwoods, Japanese pine, Korean pine and Japanese larch, heat-treated at $220^{\circ}C$, could produce high quality dark-colored boards. It is known that heat treatment decreases the hygroscopicity of wood. The hygroscopicity of major domestic softwoods and hardwoods heat-treated at $220^{\circ}C$ was investigated by a saturated salt solution method and compared with that of black and white charcoals. Equilibrium moisture contents of wood decreased with the increase of heat treatment time. Isotherm shapes of wood species were different from those of charcoals. Heat treatment decreases the equilibrium moisture contents of black locust more than those of Korean pine and Japanese larch. It was found that surface hardness of wood is improved by heat treatment to a certain extent, but a longer heat treatment causes thermal degradation, resulting in the decrease of the surface hardness.

• Journal of the Korean Wood Science and Technology
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• v.35 no.2
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• pp.29-38
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• 2007

This study was undertaken to investigate the variation of equilibrium moisture content (EMC) in transverse direction and three different directional (longitudinal, radial, and tangential) linear movements, and diffusion coefficients within a tree disc of Korean red pine (pinus densiflora). The EMC gradually increased in heartwood from pith. Therefore, the chemical components might differ even in heartwood and the radial variation in EMC might have a close relationship with the cellulose content within a cross section. The specific gravity increases gradually from pith and the porosity has not direct influence on the variation of EMC within a tree disk. Both the radial and tangential diffusion coefficients exhibited clear trend of increase from pith. The EMC change (${\Delta}EMC$) and tangential diffusion coefficient were close to be axisymmetrical but others were deviated from axisymmetry. The diffusion coefficient decreases with decreasing an activation energy and specific gravity, The diffusion coefficient increased with increasing ${\Delta}EMC$ and hygroscopicity of wood might be inversely proportional to the activation energy, The fJEMC may depend on the chemical constituents of cellulose, hemicellulose and lignin. As the number of sorption sites and sorption capacity of wood increase, therefore, it might be assumed that the hygroscopicity of wood increases while activation energy decreases. Modeling physico-mechanical behavior of wood, the variations should be considered to improve the accuracy.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.E1
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• pp.9-18
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• 2006

Aerosol hygroscopic properties were measured by a tandem differential mobility analyzer (TDMA) system during the Aerosol Characterization Experiment (ACE)-Asia campaign from 31 March to 1 May 2001. Two high flow differential mobility analyzers (DMAs) were used to maximize the count rate on board the Center for Interdisciplinary Remotely Piloted Aircraft (CIRPAS) Twin Otter aircraft. Hygroscopic growth factor distributions of particles having initial dry nanoparticle diameters of 0.040, 0.059, 0.086, 0.126, 0.186, 0.273, 0.400, and $0.586{\mu}m$ were measured during 19 research flights. Data collected during 12 of those flights were used to investigate aerosol mixing state and the influence of aerosol source region on size-resolved hygroscopicity. The uniformity in size-resolved hygroscopicity was quantified to facilitate comparison between measurements made in different air masses. Hygroscopic growth factors are strongly dependent on source region and sizes. Mean hygroscopic growth factors were observed to be greatest when the air mass origin was from the south. The mean growth factors for continental sources decreased with initial size from 1.47 to 1.27 for $0.040{\mu}m\;and\;0.586{\mu}m$, but increased with initial size from 1.44 to 1.8 for $0.040{\mu}m\;and\;0.400{\mu}m$ dry diameters for marine sources.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.1
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• pp.49-57
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• 2019

Biomass, a carbon-neutral fuel, has great advantages because it can replace fossil fuels to reduce greenhouse gas emissions. However, due to its low density, high water content, and hydrophilicity, biomass has disadvantages for transportation and storage. To improve these properties, a pretreatment process of biomass is required. One of the various pre-treatment technologies, torrefacion, makes biomass similar to coal through low-temperature pyrolysis. In this study, torrefacion treatment was carried out at 200, 230, 250, 280, and $300^{\circ}C$ for wood pellet, empty fruit bunch (EFB) and kenaf, and the feasibility of replacing coal with fuel was examined. Hygroscopicity tests were conducted to analyze the hydrophobicity of biomass, and its chemical structure changes were investigated using Infrared spectrum analysis. It was confirmed that the hygroscopicity was decreased gradually as the torrefacion temperature increased according to the hygroscopicity tests. The hydrophilicity was reduced according to the pyrolysis of hemicellulose, cellulose, and lignin of biomass.

• YAKHAK HOEJI
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• v.36 no.6
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• pp.513-517
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• 1992

The effect of solubility and hygroscopicity of some tablet diluents on the disintegration of enzyme tablets was investigated. Tablets were prepared by direct compression method using sodium starch glycolate, crospovidone, croscarmellose sodium and low-substituted hydroxypropyl cellulose as super disintegrants. Lactose, dextrose, sucrose, sorbitol and calcium phosphate dibasic were selected as typical diluents in this study. They were different in solubility (sucrose, sorbitol>dextrose>dextrose>lactose>calcium phosphate dibasic) and hygroscopicity (sorbitol>sucrose>dextrose>caicium phosphate dibasic, lactose). The disintegrants accelerated differently the disintegration of the tablets prepared with different diluents in the decreasing order of calcium phosphate dibasic>lactose>dextrose>sucrose and sorbitol. These results indicate highly soluble and/or hygroscopic diluents decrease the efficiencies of super disintegrants in the enzyme tablets.