• Journal of the Korean Wood Science and Technology
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• v.27 no.4
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• pp.38-42
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• 1999

Average moisture content of 30mm-thick Korean red pine(Pinus densiflora) was estimated nondestructively and continuously using surface temperature rise by radiation heating and moisture gradient profile in wood. The surface temperature rises increased as surface moisture contents decreased and good relationships were found between surface moisture contents and surface temperature rises at three different feed speeds of 10, 20 and 30 m/min. Average moisture content could be described as a function of surface moisture content and wood thickness.

• Journal of the Korea Furniture Society
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• v.19 no.6
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• pp.447-451
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• 2008

This study was carried out to know the difference of vapor transmission on the thickness of Paulownia wood(Paulownia tomentosa). The behavior of moisture transmission of wood thickness direction is generally estimated by vapor permeability and vapor transmission resistance. In general, Paulownia wood is known to use of inside material for furniture making, because of the excellent ability of vapor adsorption and/or desorption. Quarter sawing Paulownia wood material is prepared and the thickness is 6.0mm, 7.0mm, 8.0mm, 9.0mm, 10.0mm, respectively. The measurement of vapor transmission were conducted by the "cup method" in accordance with JIS(Japanese Industrial Standard) Z-0208. The experiment was made in the condition of 49.8mmHg vapor pressure difference and $40^{circ}C$ at constant temperature. From the experiment results, it was considered that Paulownia wood is very stable on moisture variation and any other material conditions. In this experiment we found that the vapor permeability and vapor permeance was reduced with the increase of wood thickness to vapor direction and vapor transmission resistance and specific vapor transmission resistance was increased with the increase of wood thickness to vapor direction. Besides moisture contents of adsorption and desorption side were about 5 percent and 14 percent, respectively. Mean value was 9.5 percent and about 10 percent in dry oven method. Moisture gradient was reduced with the increase of wood thickness for a small moisture difference of adsorption and desorption side.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.7
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• pp.158-167
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• 1999

Heat and moisture transfer associated with porous materials are investigated. The heat and moisture transfer in porous materials caused by the interaction of moisture gradient, temperature gradient, conduction, and evaporation are considered. The variations of temperature and moisture not only change the volume but also induce the hygro-thermal stress. The finite element formulation for solving the temperature and moisture transfer as well as the associated hygro-thermal stresses is developed. In order to verify the finite element formulation, the heat and moisture moving boundary problem in a half space and the hygro-thermo-mechanical problem in an infinite plate with a circular hole are analyzed. Temperature profile, moisture profile, and hygro-thermal stresses are compared with those of analytic solution and other investigator. Good agreements are examined

• Journal of the Korean Wood Science and Technology
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• v.39 no.2
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• pp.117-124
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• 2011

The possibility of using the properties of an ultrasonic wave as a means for monitoring the moisture content of a board during drying was investigated. The ultrasonic wave signals are influenced by moisture content and other factors such as temperature, moisture gradient and coupling area. The effect of temperature was examined by measuring the transit times, amplitudes and velocities of ultrasonic waves transmitted through air, a metal bar and a board at various temperatures. The effect of a moisture gradient was studied using a model specimen composing five wood pieces of various moisture contents. The velocity and amplitude of the ultrasonic waves transmitted through air increase with temperature, while those through a metal bar and a board decrease. It was confirmed that the temperature effect is partially attributed to the change of transducer's properties. The effect of a moisture gradient on the velocity of an ultrasonic wave varies with the average moisture content of a board. As the dimension of the end face of a board increases the velocity of an ultrasonic wave increases and low frequency components more dominates than high frequency components. The transit times of ultrasonic waves transmitted through a board during kiln drying reflect the temperature steps in the drying schedule and the transducer temperatures.

• Journal of Life Science
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• v.20 no.4
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• pp.597-601
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• 2010

Quercus dentata (Thunb. ex Murray) is a major tree found in dry habitats such as limestone areas of Korea. In order to characterize the ecological traits of Q. dentata, we treated Q. dentata saplings under four gradient levels of major environment factors such as light, soil moisture and nutrients for 5 months in a glass house. We then measured and analyzed growth differences among them. Regarding light, aboveground, belowground and plant biomass were highest at a high gradient and lowest at a low one. The root/shoot ratio was highest at the highest light gradient. Regarding moisture, no measured items were significantly affected by the moisture gradient. Regarding nutrients, aboveground, belowground and plant biomass were the highest at a slightly high gradient and the lowest at a gradient lower or higher than this. The root/shoot ratio was not significantly affected by the nutrient gradient. From these results, it was shown that the growth of Q. dentata was more affected by light and nutrients in the environment than moisture.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.1
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• pp.36-46
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• 2001

Finite element analyses of the ceramic drying process are performed. The heat and moisture movements in green ceramics caused by temperature gradient, moisture gradient, conduction, convection and evaporation are considered. The finite element formulation for solving the temperature and moisture distributions which not only change the volume but also induce the hygro-thermal stress is carried out. In order to verify the formulation, the drying process of a ceramic electric insulator is simulated. Temperature distribution, moisture distribution, and hygro-thermal stress are compared with those of other researcher. Good agreements are achieved.

• The Korean Journal of Ecology
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• v.9 no.4
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• pp.225-230
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• 1986

The environmental gradient analyses and the continum analyses were applied for the ordinationa of forest vegetation in Seonunsan area. In the soil moisture gradient, mesic to xeric, Zelkova serrata, Carpinus tschonoskii, Quercus aliena, Carpinus laxiflora, Quercus serrata, Quercus variabilis and Pinus densiflora type were arranged as a series of sequence along the gradient. In two dimensional analyses of soil moisture and organic matter gradients seven vegetation types mentioned above were also separated one another. Especially Carpinus tschonoskii in mesic-fertile sites adn Pinus densiflora in xeric-sterile were noticeable. The results of continum analyses were corresponded to those of environmental gradient analses for the forest vegetation.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.3
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• pp.347-352
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• 1999

The finite element formulation and simulation of drying process for ceramic electric insulators are investigated. The heat and moisture movements in green ceramics caused by the interaction of temperature gradient, moisture gradient, conduction, convection and evaporation are considered. The variations of temperature and moisture not only change the volume but also induce the hygro-thermal stress. The finite element formulation for solving the temperature and moisture distributions as well as the associated hygro-thermal stresses is derived. Using the computer code developed, the drying process of a ceramic electric insulator is simulated. Temperature distribution, moisture distribution, hygrothermal stress and deformed shape during the drying process are predicted.

• The Korean Journal of Ecology
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• v.21 no.4
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• pp.321-328
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• 1998

To describe the major environmental factors operating in coastal wetland and to characterize the distribution of the plant species over the wetland in relation to the major environmental gradients, 12 soil physical and chemical properties were determined. The gradient of water and osmotic potential of soil, electrical conductivity, sodium and chloride content and soil texture alsong the three habitat types of salt marshes, salt swamp and sand dune were occurred. The 24 coastal plant communities from principal component analysis (PCA) on the 12 variables were at designated as a gradient for soil texture and water potential related with salinity by Axis I and as a gradient for soil moisture and total nitrogen gradient by Axis II On Axis I were divided into 3 groups (1) 9 salt marsh communities including Salicornia herbacea communities (2) 5 salt swamp communities including Scirpus fluviatilis communities and (3) 10 sand dune communities including Jmperata cylindrica communities on Axis II were divided into 2 groups (1) salt marsh and sand dune communities, and (2) 3 salt swamp communities. The results could account for the zonation of plant communities on coastal wetland observed alsong envionmental gradients.

• The Korean Journal of Ecology
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• v.17 no.4
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• pp.471-484
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• 1994

The forest vegetation types and their structural characteristics in Mt. $Mud\v{u}ng$ were investigated by classification method and ordination method. The forest was classified into 7 communities by ristic composition table: Quercus monogolica community, Q. serrata community, Q.acutissima community, Q.variabilis community, Q.dentata community, Pinus densiflora community and Frainus mandshurica community. Considering the moisture gradient, two kinds of distributuin pattern were shown as follows; F. mandshurica, Q. acturissima, Platycarya strobilacea and Staphylea bumalda were distribute at moist habitats, while Q. monogolica, P. densiflora and Q.variabilis at dry habitats. In continuum analysis, each population occupied different distribution area but it was continuously overlapped. On the successional trends of tree species, it is postulated that Q. mongolica species might dominate the altitudinal zone over 700m.