• Journal of the Korean Wood Science and Technology
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• v.31 no.1
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• pp.10-15
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• 2003

This study was carried out to investigate a radial distribution of moisture contents(MCs) within a log cross section(LC) during oven-drying of circumferential slices cut from some of domestic hardwoods LCs. For zelkova, the slices from sapwood and from transition part already reached to below hygroscopic range at 30% in average MC, whereas the innermost slice represented about 40% MC. A moisture gradient between the innermost slice and the adjacent slice from a cherry LC became severer with drying times. For castor aralia, the green MC for heartwood slices was approximately 23% higher than that for sapwood slices, and the similar moisture gradient still lasted until average 15% MC during oven-drying. For Chinese mahogany, the MCs of the mixed slices and the innermost slice were lower than those of the slices cut from the other parts during all over drying stage.

• Advances in aircraft and spacecraft science
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• v.7 no.2
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• pp.169-186
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• 2020

Based upon differential quadrature method (DQM) and nonlocal strain gradient theory (NSGT), mechanical-hygro-thermal vibrational analyzes of shear deformable porous functionally graded (FG) nanoplate on visco-elastic medium has been performed. The presented formulation incorporates two scale factors for examining vibrational behaviors of nano-dimension plates more accurately. The material properties for FG plate are porosity-dependent and defined employing a modified power-law form. It is supposed that the nano-size plate is exposed to hygro-thermal and variable compressive mechanical loadings. The governing equations achieved by Hamilton's principle are solved implementing DQM. Presented results indicate the prominence of moisture/temperature variation, damping factor, material gradient index, nonlocal coefficient, strain gradient coefficient and porosities on vibrational frequencies of FG nano-size plate.

• Journal of the Korean Society of Tobacco Science
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• v.8 no.1
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• pp.13-21
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• 1986

The fragility, which express the fineness index, increased linearly with the moisture content for various tobacco shreds and showed a high correlation to the moisture content. Then, fineness index (FIs) at reference moisture content(l2.5%) was obtained by following equation. FIs=FIm+A(12.5-Mm) A" denote the gradient of simple linear regression equation between the fineness index and moisture content. FIm; the fineness index measured at the standard moisture content(12.5%). The characteristics of fragility concerning with some kinds of tobacco raw materials, stalk position, moisture content and storaged time were investigated. The following results were obtained. 1. The moisture content range of less fragile of tobacco raw material was from 16% to 20%. whereas the rolled process sheet tobacco was from 12% to 16%. 2. The Bright yellow and the paper process sheet tobacco were less fragile than that of the other tobacco raw materials. 3. The leaves were more distant from middle stalk position, and its become more fragile. 4. Physical properties of the storaged tobacco leaves were determined as a function of each storageunction of each storage time. The long-term storaged leaves(more than 3 years) were slightly lighter weight, more fragility and lower equilbrium moisture content than thos of the mid-term storaged leaves.(less than 3 years). 5. Contents of chemical component of the storaged leaves were determined every storage time. The long-term storaged leaves were slightly lower content of nicotine and chlorine than those of mid-term storaged leaves, but contents of crude fiber, total ash and calcium were increased significantly.

• Journal of the Korean Wood Science and Technology
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• v.28 no.2
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• pp.19-24
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• 2000

Effects of the cross-sectional dimension and moisture profile of wood specimens on the ultrasonic sound velocities of radiata pine heartwood and sapwood. Each moisture profile model specimen was made by composing five wood pieces with various moisture contents. As the cross-sectional dimensions decreased the ultrasonic velocities of both heartwood and sapwood decreased by 4~8%. In the ultrasonic signals transmitted through the specimens low frequency components more dominated than high frequency components as the dimension of cross section increased. The specimens with the same average MCs and different moisture profiles showed different ultrasonic velocities. By plotting the ultrasonic velocities against the average moisture contents of the inner three pieces of the moisture profile model specimens it was revealed that three distinct plot patterns existed.

• Journal of the Korean Wood Science and Technology
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• v.24 no.1
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• pp.75-80
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• 1996

The purpose of this study is to clarify the mechanism of moisture transfer depend on the thickness of the spruce(Picea sitchensis Carr.). Therefore, as the basic research of moisture transmission, the amount of moisture transmission and the moisture distribution in specimens and temperature of it's surfaces in vapor transmission process were investigated. The experiment was conducted in a steady state. and the moisture distribution was measured by knife cutting and weighing the specimens. The following conclusions were obtained ; 1. It can be found that distribution of moisture in the specimen can be approximated by two different straight lines intersecting at nine or ten percent moisture content. The amount of moisture movement defends on the gradient of moisture in the wood. 2. It is investigated that the wood surface moisture contents(MCs) are less for thinner specimens than for thick ones on the absorption side. On the other hand, the wood surface MCs are greater for thinner specimens than for thick ones on the desorption side. The main factor that affects the EMC of wood would be temperature when the relative humidity of atmosphere is constant. The specimen generate heat with the absorption and desorption process. In addition, the velocities of moisture transmission varied with the thicknesses of specimens. If the temperature of wood becomes greater, its MC decreases. Then the difference between surface MC and EMC of adsorption and desorption side becomes greater for thinner specimens. Therefore it is considered that the coefficients of moisture transfer decreases with the increases of the specimens' thicknesses.

• The Journal of Engineering Geology
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• v.15 no.3
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• pp.281-288
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• 2005

To evaluate a property of moisture distribution and volumetric water content on bentonite media the responses of complex dielectric constant were used which are measured by Frequency Domain Reflectometry with Vector Network Analyzer (FDR-V) system. The bentonite is widely used a barrier liner system in the waste disposal site, recently. In case of barrier liner system, generally, the coefficient of permeability should have to less than 10-7cm/sec. According to the results, the complex dielectric constants are increasing with increase the volumetric water content and temperature together. Also the variation of complex dielectric constant due to temperature gradient is confirmed that the moisture movements are increasing with the variations of temperature from high range to low range, which is represented the property of moisture distribution in the bentonite.

• Journal of the Korean Wood Science and Technology
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• v.31 no.1
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• pp.27-31
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• 2003

This paper presents the results of air-drying processes and mositure content (MC) distribution of red pine (P. densiflora) and Japanese larch (L. leptolepis) square timber with 14 cm and 16.5 cm of face size, respectively. The air-drying rates of square timber were comparatively high during the first 8 weeks, after that gradually decreased. The time to air dry square timber from initial MC to specified MC of 18 percent required about 26 weeks for 14.0 cm and 32 weeks for 16.5 cm square of red pine, and 32 weeks for 14.0 cm and 48 weeks for 16.5 cm square of Japanese larch. The longitudinal- and transverse MC distribution of these air-dried squares showed slight moisture gradient. The effect of face size on moisture gradient of Japanese larch square was more pronounced comparing with red pine one.

• International Journal of Highway Engineering
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• v.7 no.1 s.23
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• pp.31-38
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• 2005

Concrete has higher vapor pressure than its surrounding ambient air immediately after placement. Moisture at concrete surface evaporates to the ambient air to adjust equilibrium of the vapor pressure between them. The moisture inside the concrete moves to the surface because the evaporation at the surface causes gradient of vapor pressure inside the concrete. Plastic cracking, degree of hydration, strength development, and others caused by velocity of the moisture movement significantly influences quality of concrete. In this paper, the moisture diffusivity of early-age concrete was back-calculated using governing equation of the moisture diffusion, and temperature and relative humidity of concrete measured in a laboratory. The moisture diffusivity of the concrete was modeled using the back-calculated moisture diffusivity. The relative humidity of the concrete calculated by finite element method (FEM) using the modeled moisture diffusivity as Input data coincided with the measured relative humidity well.

• Journal of Forest and Environmental Science
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• v.38 no.4
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• pp.229-238
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• 2022

Q. mongolica and Q. dentata are representative species of deciduous forest communities in Korea and are known to be relatively resistant to soil drying condition among Korean oaks. This study attempted to elucidate the degree of competition and ecological niche characteristics of the two species by comparing the ecological responses of the two species according to soil moisture. Competition between Q. mongolica and Q. dentata was shown to be more intense under the conditions where moisture content was low than under the conditions where moisture content was high. As for the ecological niche overlaps of the two species for soil moisture, the structural traits of plant such as stem diameter overlapped the most, the traits of biomass such as petiole weight overlapped the least, and photosynthetic organ-related traits such as leaf width and length overlapped intermediately. When looking at the competition for soil moisture between the two species, it can be seen that Q. mongolica won in nine traits (leaf width length, leaf lamina length, leaf lamina weight, leaf petiole weight, leaf area, leaves weight, shoot weight, root weight, and plant weight) and Q. dentata won in the remaining seven traits (leaf petiole length, leaves number, stem length, stem diameter, stem weight, shoot length, and root length). Competition between the two species for the moisture environment of the soil was shown to be intense under the conditions where moisture content was low. The degree of competition between Q. dentata and Q. mongolica for soil moisture is high under the conditions where soil moisture content is low, and it is judged that Q. mongolica is more competitive for soil moisture than Q. dentata.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1061-1064
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• 2008

A completion of settling process takes a lot of time for dredged materials of high moisture content, such as contaminated sludge, in landfill site. In general, additives (e.g. flocculants) are used for reducing settling time of such colloidal material, which results in the increase of sludge volume, and hence much space is required in landfill site. This study is to suggest alternative method in order to enhance the settling process of cohesive clayey soils. A number of gravitational sedimentation tests as well as electrokinetic experiments were conducted to investigate the variation of initial moisture content on the settling behaviour of clay slurry. Surface settlement, electric current and local voltage gradient were monitored during the experiment, and moisture content and soil pH were measured after the experiment. From the results, the application of electrokinetics was found to be effective in volume reduction (i.e. increase of settling velocity and decrease of final moisture content) by comparison with gravitational settling process.