• The Korean Journal of Ecology
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• v.28 no.5
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• pp.265-270
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• 2005

In order to investigate the organic carbon distribution, net primary production, annual litter production, organic carbon in litter layer, soil organic carbon and soil respiration were studied in an oak forest, Kongju, Chungnam Province in Korea. Net primary production was estimated to 15.84 ton $C{\cdot}ha^{-1}{\cdot}yr^{-1}$. The amount of carbon allocated to leaf and reproductive organ, branch, stem and root was 1.71, 4.03, 7.34, 2.76 ton $C{\cdot}ha^{-1}{\cdot}yr^{-1}$ respectively. Annual litter production was 5.21 $ton{\cdot}ha^{-1}{\cdot}yr^{-1}$, which amounted to 2.35 ton $C{\cdot}ha^{-1}{\cdot}yr^{-1}$. Average amount of organic carbon in litter layer (L+F) was 6.06 ton C/ha, and that of L layer decreased from winter through summer. Soil organic carbon decreased along the soil depth. Average amount of soil organic carbon in this oak forest was 165.19 ton C/ha. The amount of carbon evolved through soil respiration was 11.24 ton $C{\cdot}ha^{-1}{\cdot}yr^{-1}$. Net amount of 4.60 ton $C{\cdot}ha^{-1}{\cdot}yr^{-1}$ was absorbed from the atmosphere by this oak forest.

• Journal of Ocean Engineering and Technology
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• v.20 no.4 s.71
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• pp.43-49
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• 2006

Detailed investigations were carried out on the stability of the dredged soil bed against wave actions, aimedat establishing the design method of artificial tidal flats using dredged soil. The soil was dredged at Nagoya port, Japan, and has a mean grain size of 0.013mm. Basic features of artificial dredged soil bed against wave actions were explained from a series of model experiments in a wave flume. The two types of section shapes were employed; one is a horizontal bed and the other is a sloped one. Changes of the bed profile, shear strength, grain size distribution and water content, according to the wave actions, were measured in detail. The cumulative effect of the wave actions, over about one week, was investigated. A dredged soil bed moves withthe wave actions with relatively small wave height. It should be especially. noted that the clay component is dissolved and flown out, away from the surface layer, and consequently the surface layer hardens, as if it is covered with sand. Wren the wave height is gradually increased, the bed is not liquefied and the shear strength of the dredged bed is increased by a wave-induced dissipation of pore pressures in the bed and a decrease of clay component by the wave-induced leakage.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.5
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• pp.336-344
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• 2017

The soil water characteristics curve (SWCC) represents the relation between soil water potential and soil water content. The shape and range of SWCC according to the relation could vary depending on soil characteristics. The objective of the study was to estimate SWCC depending on soil types and layers and to analyze the trend among them. To accomplish this goal, the unsaturated three soils were considered: silty clay loam, loam, and sandy loam soils. Weighable lysimeters were used for exactly measuring soil water content and soil water potential. Two fitting models, van Genuchten and Campbell, were applied. Two models entirely fitted well the measured SWCC, indicating low RMSE and high $R^2$ values. However, the large difference between the measured and the estimated was found at the 30 cm layer of the silty clay loam soil, and the gap was wider as soil water potential increased. In addition, the non-linear decrease of soil water content according to the increase of soil water potential tended to be more distinct in the sandy loam soil and at the 10 cm layer than in the silty clay loam soil and at the lower layers. These might be seen due to the various factors such as not only pore size distribution, but also cracks by high clay content and plow pan layers by compaction. This study clearly showed difficulty in the estimation of SWCC by such kind of factors.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09b
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• pp.76-80
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• 2010

This paper describes that estimation methods for the distribution of consolidation settlements to investigate the influence of distribution characteristics of compression index on the spatial distribution of consolidation settlements. When the variation of compression index is considerable, the spatial distribution of compression index is estimated using ordinary cokriging. The spatial distribution of consolidation settlements estimated by considering both the variation of compression index and void ratio (CASE-1) is different from the conventional mean value of all soil properties (CASE-2). The settlement of CASE-1 shows the larger variation at short distances rather than that of CASE-2. Whereas the spatial settlement distribution of CASE-1 is affected by the spatial distribution of compression index and the thickness of consolidation layer, the distribution of CASE-2 is significantly influenced by the distribution of the thickness of consolidation layer.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.528-535
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• 2005

Using the case of design to the Large diameter Bored Pile, We showed the various method to estimate the Lateral coefficient of subgrade reaction and analyzed the lateral displacement behavior according to the characteristics of sub layer distribution. According to the study, Mutual relation to the N value and the soil modulus of deformation showed 400N to 800N to the fine grained soil and weathered soil. It showed simular tendancy with the proposed expression of Schmertmann. But Weathered rock was over estimated as 4,200N. $k_h$ to the sedimentory soil and weathered rock each showed these orded of Schmertmann-PMT-2,800N and Schmertmann-2,800N-PMT. As the factor($\alpha$) 4 was applied to the estimation in weathered rock, $k_h$ to the PMT was calculate as a big value. If the pile is long and the pile is surpported to the soil, Lateral displacement was in inverse proportion ratio to the value of $k_h$. But the case of shallow soil layer(early bedrock) and the short pile, Lateral displacement was affected by the behavior of socheted pile to the bedrock not by the upper soil layer.

• Journal of Ecology and Environment
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• v.32 no.1
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• pp.27-31
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• 2009

Organic carbon (OC) distribution in 32-year-old pitch pine plantation at Mt. Hotae in Kongju, Korea, was studied from August 2007 to July 2008. In order to investigate the OC distribution, OC in plant biomass, litterfall, litter layer on forest floor, and soil within 50cm depth were estimated. The density of P. rigida plantation was 3,200 trees/ha, average DBH was $18.7{\pm}5.53cm$ and average tree height was $11.1{\pm}1.85m$. Organic carbon stored in plant biomass, litterlayer on forest floor and soil in 2008 was 89.46 ton C/ha (46.09%), 4.32 ton C/ha (2.23%) and 100.32 ton C $ha^{-1}$ 50cm-$depth^{-1}$ (51.68%), respectively. Amount of OC returned to forest floor via litterfall was 2.21 ton C $ha^{-1}\;yr^{-1}$. Total amount of OC stored in this P. rigida plantation was 194.1 ton C/ha. Net increase of OC in above- and below-ground biomass in this pitch pine plantation was 4.82 ton C $ha^{-1}\;yr^{-1}$.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.2
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• pp.61-70
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• 2000

The purpose of this study is to identify the proper species of turf and the ground structure for the turf sports grounds. Analysis items are particle distribution of sand and gravel, saturated hydraulic conductivity, soil hardness, and turf growth. Results of this study are as follows. 1)The particle distribution of sand used in the multi-layer rootzone is within the upper limit of the standard level. The diameter of mid-size grain({TEX}$D_{50}${/TEX})was 0.62mm and the value of uniformity ({TEX}$D_{90}${/TEX}/{TEX}$D_{10}${/TEX}) was 3.93. The particle size distribution of sand used in the single-layer rootzone was beyond the standard level as {TEX}$D_{50}${/TEX})=0.86 and {TEX}$D_{90}${/TEX}/{TEX}$D_{10}${/TEX}=8.86. 2) Saturated hydraulic conductivity of the sand was higher in the multi-layer rootzone than in the single-layer rootzone while bulk density was vice versa. 3) Surface hardness was high on Kentucky bluegrass+perennial ryegrass compared to zoysiagrass probably caused by root density. 4) Visual covering and visual rating were highly evaluated on zoysiagrass within summer while better evaluated on Kentucky bluegrass+perennial ryegrass throughout fall to spring. 5) Visual color was better evaluated on Kentucky bluegrass+perennial ryegrass than on zoysiagrass throughout the year. These studies are demanded urgently according to increase in interest in the ground and turf species of the turf sports ground because of World Cup 2002.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.431-434
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• 2004

To understand the stratigraphy for a hydrogeological setting, borehole logging data are used. The test site is located in Mangyeong-river bank area in Dodeok-dong Jeonju. 11 boreholes are developed to monitor groundwater level and quality. Based on the borehole data, SOLID model is used to get the distribution of each layer.

• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.1097-1107
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• 2020

Assessment of soil carbon stock is essential for climate change mitigation and soil fertility. The digital soil mapping (DSM) is well known as a general technique to estimate the soil carbon stocks and upgrade previous soil maps. The aim of this study is to calculate the soil carbon stock in the top soil layer (0 to 30 cm) in Jeolla Province of South Korea using the DSM technique. To predict spatial carbon stock, we used Cubist, which a data-mining algorithm model base on tree regression. Soil samples (130 in total) were collected from three depths (0 to 10 cm, 10 to 20 cm, 20 to 30 cm) considering spatial distribution in Jeolla Province. These data were randomly divided into two sets for model calibration (70%) and validation (30%). The results showed that clay content, topographic wetness index (TWI), and digital elevation model (DEM) were the most important environmental covariate predictors of soil carbon stock. The predicted average soil carbon density was 3.88 kg·m-2. The R2 value representing the model's performance was 0.6, which was relatively high compared to a previous study. The total soil carbon stocks at a depth of 0 to 30 cm in Jeolla Province were estimated to be about 81 megatons.

• Journal of Forest and Environmental Science
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• v.34 no.6
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• pp.429-434
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• 2018

Extractable iron (Fe), manganese (Mn), zinc (Zn) and copper (Cu) contents and their distribution with depths in soils of forested and adjacent deforested areas at Jahazpura, Teknaf, Cox's Bazar of Bangladesh were studied. The soils under forest showed higher levels of DTPA-extractable micronutrients in all three layers of soil in comparison to those of the deforested areas. The differences between forested and deforested sites were, in most cases, significant.. The top soils of forested sites had the higher contents of micronutrient and generally decreased with depth in forested soils, while there was no regular trend of distribution in deforested soils. The study also revealed that contents of extractable Fe, Mn and Cu were sufficient in all depths and sites but Zn was deficient in bottom layer of forested and all three layers of deforested sites. The results suggested that organic matter, clay and soil pH could play important roles in concentrations and distributions of micronutrients in soils of the study areas.