• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.2
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• pp.88-99
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• 2007

Soil moisture is one of the essential components in determining surface hydrological processes such as infiltration, surface runoff as well as meteorological, ecological and water quality responses at watershed scale. This paper discusses soil moisture transfer processes measured at hillslope scale in the Gwangneung forest catchment to understand and provide the basis of stochastic structures of soil moisture variation. Measured soil moisture series were modelled based upon the developed univariate model platform. The modeling consists of a series of procedures: pre-treatment of data, model structure investigation, selection of candidate models, parameter estimation and diagnostic checking. The spatial distribution of model is associated with topographic characteristics of the hillslope. The upslope area computed by the multiple flow direction algorithm and the local slope are found to be effective parameters to explain the distribution of the model structure. This study enables us to identify the key factors affecting the soil moisture distribution and to ultimately construct a realistic soil moisture map in a complex landscape such as the Gwangneung Supersite.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.3
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• pp.175-180
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• 2016

Nondestructive evaluation for material health monitoring is important in aerospace industries. Composite laminates are exposed to heat cyclic loading and humid environment depending on flight conditions. Cyclic heat loading and moisture absorption may lead to material degradation such as matrix breaking, debonding, and delamination. In this paper, the moisture absorption ratio was investigated by measuring the Lamb wave velocity. The composite laminates were manufactured and subjected to different thermal aging cycles and moisture absorption. For various conditions of these cycles, not only changes in weight and also ultrasonic wave velocity were measured, and the Lamb wave velocity at various levels of moisture on a carbon-epoxy plate was investigated. Results from the experiment show a linear correlation between moisture absorption ratio and Lamb wave velocity at different thermal fatigue stages. The presented method can be applied as an alternative solution in the online monitoring of composite laminate moisture levels in commercial flights.

• Journal of Bio-Environment Control
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• v.16 no.2
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• pp.135-141
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• 2007

Although the result of the tree height growth after water treatment, Fraxinus rhynchophylla has little affection by the artificial water treatment, the growth showed decreased tendency as the soil moisture decreased, and F. mandshurica showed high growth in relatively high soil moist $78{\sim}90%$ treated area. The growth of root collar diameter of F. rhynchophylla and F. mandshurica also showed decreased tendency as soil moisture decreased. The changes of biomass according to dry weight of root, stem, leaves of F. rhynchophylla demonstrating statistical significance as moisture contents of soil is lower showing decreased biomass tendency and in the treatment of $78{\sim}90%$(A) moisture content showed more than double the higher biomass compare to the treated area of $18{\sim}30%$(D) moisture contents. Also F. mandshurica showed statistical significance in A and D treatment demonstrating differences among each treatment. This can be purported to have physiological effects like weakening of seedling and softening of tissues including leaves as soil moisture decreased. Ultimately it is regarded to the main reason of unsatisfactory growth for F. rhynchophylla and F. mandshurica that are weak to drought resistance. SLA, which is one of the special traits of leaf area of F. rhynchophylla, didn't show statistical significance between moisture process, it demonstrated decreased tendency as the moisture content interval is minimal. LAR and LWR showed increased tendency while moisture content didn't show statistical significance between treatments as they are minimal.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.3
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• pp.241-247
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• 2009

It is important to satisfy the requirements and standards for the protections of passengers in a car accident. There are lots of studies on the crushing energy absorption of a structure members in automobiles. We have studied to investigate collapse characteristics and moisture absorption movements of CFRP(Carbon Fiber Reinforced Plastics) hat shaped sectional members when CFRP laminates are under the hygrothermal environment. In particular, the absorbed energy, mean collapse load and deformation mode were analyzed for side members which absorbed most of the collision energy. Variation of CFRP interlaminar numbers is important to increase the energy absorption capability. Therefore we have made a static collapse experiment to research into the difference of absorbed energy and deformation mode between moisture absorbed specimen and non-moisture absorbed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.5
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• pp.507-513
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• 2009

It is important to satisfy the requirements and standards for the protections of passengers in a car accident. There are lots of studies on the crushing energy absorption of structure members in automobiles. We have investigated collapse characteristics and moisture absorption movements of CFRP(Carbon Fiber Reinforced Plastics) hat shaped sectional members when CFRP laminates are under the hygrothermal environment. The absorbed energy, mean collapse load and deformation mode were analyzed for side members which absorbed most of the collision energy. Therefore we have made a static collapse experiment to research into the difference of absorbed energy and deformation mode between moisture absorbed specimen and non-moisture absorbed specimen.

• Journal of Ocean Engineering and Technology
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• v.13 no.4 s.35
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• pp.63-74
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• 1999

This study has been investigated about the influence of moisture environment on the mechanical properties in the carbon fiber cross laminates. And it has been also investigated the effect of unit ply thickness of the carbon fiber cross laminates on the mechanical properties in distilled water of $80^{\circ}C$ for a certain period of time. As a results, it was found that the weight gain of water was increased with the immersion time and the bending strength and fracture toughness were decreased with the weight gain of water. And it was also shown that the bending strength and fracture toughness were decreased with the increasing of the unit ply thickness of carbon fiber cross laminates through the immersion time.

• Fibers and Polymers
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• v.4 no.4
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• pp.215-221
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• 2003

A vertical skin model with two detachable environmental chambers was developed to simulate a Human-Clothing-Environment system and to evaluate heat and moisture transport properties of textile materials under severe conditions and during transient states. The construction of the system was described and data reproducibility and accuracy of the instrument were verified by using PEG treated nonwovens. Also advantages over a traditional static type experiment were demonstrated based on a series of experiments.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.E
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• pp.9-17
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• 1998

Oxides of nitrogen play important roles in atmospheric chemistry. Soil has been recognized as a major natural source of NO, and its emission depends on soil parameters such as soil nitrogen availability, soil moisture and temperature. It is necessary to understand effects of these controlling parameters on soil NO emission. In order to understand soil moisture effects on NO emission, variations of NO concentration and existence of its equilibrium concentration were observed from ammonium fertilized Japanese upland soil prepared for different soil moisture conditions. The closed chamber technique was employed for this study. The significant increases in NO with soil moisture were found. Maximum was occurred at sample ID4 (55% of water-filled pore space (WFPS)), but it decreased as soil moisture increased. No significant NO concentration was emitted from soil sample without fertilizer, but there was significant NO in fertilized soil samples. The magnitudes of NO from soil increased with time and reached at steady state within ten minutes approximately. These results suggest that nitrogen input from fertilizer takes charge in the first step of sharp increase in NO emission, and then soil moisture becomes important factor to control NO emission from the soils. NO concentrations from soil were compared to those one-day after the experiment. Results from the comparison analysis suggest that the soil NO flux might have been stimulated by soil disturbances like mixing, and this is much more effective in dry soils rather than in wet soils. It was found that much less NO came out from soils after a day; suggesting that most of NO was released from the soils within a day after fertilizer application during our experiment. The length of NO releasing time span may depend on the amounts of fertilizer applied, soil moisture condition, and other soil physical parameters.

• Journal of Animal Environmental Science
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• v.21 no.3
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• pp.99-104
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• 2015

According to the volumetric mixing rate of dairy cow manure (DCM) and moisture control materials such as decomposed manure (DM) and sawdust (S), 6 reactors (DCM only (R1), DCM : DM = 1:1 (R2), DCM : DM = 1.5:0.5 (R3), DCM : DM = 0.5:1.5 (R4), DCM : DM:S = 1:0.5:0.5 (R5) and DCM : S = 1:1 (R6)) were used for composting of dairy cow manure. Among the composting reactors, composting reactor of R5 was shown the highest temperature of the compost as a $66^{\circ}C$ during composting period. After 3 weeks composting, moisture content of R5 and R6 were 51% and 51.3%, respectively. These values were satisfied with the moisture content standard of livestock manure compost of Korea. We concluded that decomposed manure may be a good moisture control material for dairy cow manure composting when it is used in mixture with sawdust. The optimum volumetric mixing ratio of dairy cow manure and moisture control materials was 50% of livestock manure, 25% of decomposed manure and 25% of sawdust.

• Journal of Ocean Engineering and Technology
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• v.32 no.5
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• pp.367-371
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• 2018

Plywood is one of the important materials in LNG cargo containment systems, and, due to the characteristics of the wood, its properties vary greatly depending on the humidity conditions in the storage facility. Due to the distribution environment of plywood, there is a high probability of long-term exposure to the domestic seasonal environment. Considering an environment in which the humidity changes greatly according to the seasons in Korea and the characteristics of the wood, it is necessary to acquire data on changes in the characteristics of the plywood for accurate quality control. In this study, the moisture content of plywood was determined experimentally to reflect the seasonal environmental conditions of shipyards in Korea. A noticeable change in the thermal conductivity was confirmed experimentally.