• Journal of the Korean GEO-environmental Society
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• v.9 no.5
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• pp.83-89
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• 2008

This study is to figure out the speed of soil diffusion and shapes as well when landslide occurred. It was measured the speed and shapes of soil diffusion using installed indoor-simulation of a land slide. Standard sand was used to measure it and this measurement is following the moisture content of standard sand. The result of this experiment follows the moisture content; as the moisture content goes up, the area and speed of soil diffusion goes faster as well. As the average of records by the moisture content was analyzed, the area and speed of land slide are increased proportionally. The shape of diffusion is formed as fanwise. It depends on the moisture content as above; the speed was fast when the moisture content is high, and it was getting narrower and longer as the speed of diffusion was faster.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.303-308
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• 1998

In the concrete structures exposed to environmental conditions at early ages, water movement occurs by moisture diffusion in the concrete, and self-desiccation of concrete is also occurred. Thus the internal relative humidity is changed from moisture diffusion and self-desiccation. Thus the internal relative humidity at each location in concrete includes the decrease by self-desiccation. Especially, for high-strength concrete the much unit cement content is used, so that the non-uniform relative humidity distribution is affected form self-desiccation at early ages. In this study, the internal relative humidity in concrete was measured at early ages, and the moisture diffusion component and self-desiccation component of total relative humidity were discussed.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.2
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• pp.11-15
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• 2011

Heat transfer equation is first reviewed and then governing equation of moisture diffusion. Analogy scheme is applied to analysis the moisture absorption problem of polymers. It make possible to numerically analyze the diffusion problem for single medium by using commercial finite element code if it is under the isothermal loading condition. It is extended to special multimaterial system by introducing pressure ratio function, whose moisture characteristics of materials are proportional to temperature only. The weight changes of silicon-nonconductive-polymer joint model due to moisture absorption is measured and been very close to the numerical results as for single media with boundary condition with zero concentration, but yields numerical errors as for multisystem media.

• Current Research on Agriculture and Life Sciences
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• v.10
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• pp.41-47
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• 1992

In general, the behavior of moisture transmission is estimated by vapor permeability or vapor transmission resistance, but its values obtained by experiments do not have great adaptability for practical situations because of changes in the experimental conditions. This fact is why only theoretical discussions have advanced. Thus, the fundamental study of the moisture transmission phenomenon has been treated lightly. Here, as the first step toward the basic research of moisture transmission, the amount of moisture transmission and the moisture distribution in specimens were investigated. The experiment was conducted in a steady state, and the moisture distribution was measured by slicing and weighing the specimens. From the examination of the vapor transmission resistance, the phenomenon of moisture transmission was dealt with devide the moisture transfer on the wood surface and moisture diffusion in wood. The following results were obtained. 1) The phenomenon of moisture transmission should be approached by its division into moisture transfer on the wood surface and moisture diffusion in the wood because the positive values of vapor transmission resistance exist in the extrapolation of thickness 0mm. 2) The distribution of moisture in wood can be illustrated by two straight lines intersecting at the point of nine percent moisture content : namely, diffusion coefficients have two constant values at moisture contents below and above nine percent. The shape of the distribution curve of moisture content is similar irrespective of the wood thickness. On the other hand, when the moisture contents on both sides was more than nine percent, the distribution of the moisture content could be illustrated by one straight lines. 3) The amount of moisture movement is determined by the moisture gradient in wood. 4) Coefficients of the moisture transfer depend on the thickness of the specimens.

• Honam Mathematical Journal
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• v.32 no.2
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• pp.193-202
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• 2010

We investigate the estimation of the moisture transfer coefficients in porous media by optimization technique which minimizes the functional defined by the squares error of the numerical solution of an inverse diffusion problem from their experimental values of the moisture content at the some time-steps. In this paper, we solve a diffusion equation numerically by the control volume finite element methods.

• Journal of the Korea Furniture Society
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• v.20 no.6
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• pp.599-604
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• 2009

For the search of unified law of moisture movement in wood, moisture distribution of Korean red pine at non-steady state was investigated. We assume that the equilibrium moisture content (EMC) in wood depends on only temperature and relative humidity, it can be control in temperature and humidity chamber. If temperature is constant and humidity or vapor pressure is changed with sin curve shape at adequate cycles, EMC in chamber can be changed as well with sin-curve shape. The setup condition of a non-steady state in humidity control chambers is a constant temperature at $20^{\circ}C$ and 15+10 sin ${\omega}t$ percent EMC. It can be found that the distribution of moisture in the specimen with varying relative humidity are illustrated various types. Moisture in wood is complicated and vibrates with the moisture sorption process. Considering a unified law of moisture movement in wood, it is considered that the most important fact is to search the method of precise diffusion & transfer coefficients.

• Computers and Concrete
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• v.13 no.3
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• pp.361-375
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• 2014

The moisture transport in underground concrete was experimentally investigated and the nonlinear model of moisture transport considering the effects of water diffusion, hydration of cementicious materials and water permeability was proposed. The consumed moisture content by self-desiccation could be firstly calculated according to evolved hydration degree of cement and mineral admixtures. Furthermore, the finite differential method was adopted to solve the moisture transport model by linearizing the nonlinear moisture diffusion coefficient. The comparison between experimental and calculated results showed a good agreement, which indicated that the proposed moisture model could be used to predict moisture content evolution in underground concrete members with drying-wetting boundaries.

• Journal of the Semiconductor & Display Technology
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• v.12 no.1
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• pp.23-28
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• 2013

Epoxy resins are widely used in microelectronics packaging such as printed circuit board and encapsulating for semiconductor manufacturing. Water can diffuse into and through the epoxy matrix systems and moisture absorption at boarding interfaces of matrix resin systems can lead to a hydrolysis at the interfaces resulting in delamination of encapsulating materials. In the study, the changes of diffusion coefficient and moisture content ratio of epoxy resin systems with nano-sized fillers according to the change of liquid type epoxy resins were investigated. RE-304S, RE-310S, RE-810NM and HP-4032D as a epoxy resin, Kayahard AA as a hardener, and 1B2MI as a catalyst were used in these epoxy resin systems. After curing, moisture content ratios were measured with time under the 85 and 85% relative humidity condition using a thermo-hydrostat. The maximum moisture absorption ratio and diffusion coefficient of EMC decrease with the filler content. It can be seen that these decreases are due to the increase of filler surface area and the decrease of moisture through channel with the content of nano-sized filler.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.1
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• pp.46-51
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• 2004

The film coated snap bean (Phaseolus vulgaris) seeds with five different coating materials treated with 3% increase in seed weight were planted at sandy loam soil controlled moisture content of 18, 19, 20 and 21 %. The oxygen diffusion rate (ODR) was calculated from the different moisture content soil. The number of normal seedlings, seedling vigor, and seedling capability in field (seed vigor x dry matter weight) were observed at 9 days after planting and compared to the changes of ODR. The germination rate and ODR were sharply decreased simultaneously in the seeds planted at 21 % soil moisture content. Seedling emergence did not occur at all as the soil moisture content increased above 22 %. Hence this value should be considered as the threshold of soil moisture content for seedling emergence. An ODR value under 20% did not influence the percent emergence significantly. The certain difference observing in the emergence at the same ODR was not related clearly to the condition of soil. So it can be assumed that the limit of soil moisture content for the emergence of snap bean was approximately 20%. The value of 18% soil moisture content may be considered as the optimum for snap bean emergence. There was close relationship between the mean value of ODR in different soil moisture contents and the emergence. The germination rates of the seeds coated with the different materials were quite different when the seeds were planted at 21 % soil moisture. Dry weight of the seedlings from film coated seeds was decreased slightly, but the germination rates were not much different from the non-treated control under relatively higher soil moisture content (21 %). Major factor lowering emergence rate was oxygen stress while film coating act as a minor constraint for snap bean sown in excess soil moisture condition.

• Journal of the Korean Wood Science and Technology
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• v.20 no.4
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• pp.21-30
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• 1992

An activation energy equation for moisture diffusion in wood was developed with an assumption that activation energy is directly proportional to wood specific gravity. Theoretical activation energies obtained from the activation energy equation were revealed to be always lower than actual activation energies, which implies that activation energy isn't affected only by wood specific gravity. The other affecting factors are possibly anatomical structures of wood which determine a ratio of vapor diffusion to bound water diffusion in wood. For the convenience of estimating actual activation energy by using the activation energy equation, thirteen kinds of species were categorized into three groups according to their anatomical structures.