• 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.

• Korean Journal of Environmental Agriculture
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• v.27 no.1
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• pp.66-71
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• 2008

Phosphorus transfer from agricultural soils to surface waters is an important environmental issue. Fly ash and phospho-gypsum which are industrial by-product were investigated as a means of reducing dissolved phosphorus in arable soil. To determine the optimum mixing ratio of fly ash(FA) and phospho-gypsum(PG) for reducing dissolved reactive P(DRP) in soil, various mixture ratio of FA and PG were mixed with two soil. The DRP content and pH in soils were analysed after 3 weeks incubation under flooding condition. Although DRP content in soils was significantly decreased by FA-PG mixture compared with control, there were no significant difference among the FA and PG mixture ratio of 75:25, 50:50, and 25:75. The mixture of 75% FA and 25% PG was selected for field test. A field experiment was carried out to evaluate the reducing DRP content in paddy soil to which 0(NPK), 20(FG 20), 40(FG 40), and 60(FG 60) Mg $ha^{-1}$ of the mixture were applied. The DRP content was reduced by 31% at the application rate of 60 Mg $ha^{-1}$. In contrast to deceasing DRP, Ca-P content increased significantly with the mixture application rate. After rice harvesting, available $SiO_2$, P, and exchangeable Ca content in soil increased significantly with application rate due to high content of Si, P, and Ca in the mixture. Mixtures of fly ash and gypsum should reduce P loss from paddy soil and increase soil fertility.

• Journal of the Korean Geosynthetics Society
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• v.9 no.3
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• pp.39-45
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• 2010

When the ground temperature drops below $0^{\circ}C$, wet soils expand due to the ice formation in their porous space. This results in frost heave which causes structural stability problems. Frost heave is attributed by several factors such as physical soil properties and heat transfer including pore water phase change. Due to the complex physical phenomena, reliable and verified multi-dimensional numerical models for frost heave problems are still in a research stage. This study presents an efficient and simple method of overcoming numerical problems associated with sudden jump of heat capacity due to the phase change from water to ice in the pore space. This paper proposes heat transfer equation and finite element method when the saturated soils or porous rocks are subjected to freezing. Numerical analyses using the proposed method agree well with the known closed form solution and the laboratory test results.

• Journal of Environmental Health Sciences
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• v.47 no.2
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• pp.144-154
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• 2021

Objectives: This study was intended to identify hazard contribution by region, media, and chemical by calculating a hazard-based index using pollutant release and transfer register (PRTR) data. Methods: PRTR data for the period 2011 to 2016 was analyzed to examine the regional trends in toxic releases in terms of quantity and to create a corresponding hazard-based index. For the hazard-based index, the Risk-Screening Environmental Indicators (RSEI) Model was used. Results: The results of the trend analysis show that total releases decreased slightly, but health hazard levels increased consistently. According to the outcome of regional contribution analysis of the hazard-based index, Chungcheongnam-do, Jeollabuk-do and Gyeonggi-do Provinces showed a high ratio in the index for air and water release pollutants, while Gyeongsangbuk-do and Gyeongsangnam-do Provinces showed a high ratio in the index of soil release and waste transfer pollutants. Also, as a result of the analysis of the top ranked substances in the hazard-based index, it was found that chromium, cobalt and its compounds, and ethylene oxide contributed greatly to air release substances, while chromium, benzene, and lead and its compounds contributed greatly to water release substances. Conclusion: These results showed considerable disparities between total release and health hazard levels, especially in the analysis of contribution by regions and by chemical substance. Therefore, the hazard-based index should be used both to support a more comprehensive and robust approach to screening of chemicals for environmental health policy and for management.

• Journal of the Korean Geotechnical Society
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• v.27 no.10
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• pp.55-67
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• 2011

The shear load distribution and deformation of offshore friction piles are investigated using experimental tests and a numerical analysis. Special attention is given to the soil-pile interaction of axially loaded pile. A framework for determining the f-w curve is proposed based on both theoretical analysis and experimental load test data base. A numerical analysis that takes into account the proposed f-w curves was performed for major parameters on pile-soil interaction such as the pile diameter, the pile length, and the soil condition. Based on the analysis, it is shown that the proposed f-w method is capable of predicting the behavior of a friction pile in deep soft clay. Through comparisons with case histories and finite element results, it is found that the proposed f-w curves are more appropriate and realistic m representing the pile-soil interaction of axially loaded piles in deep soft clay than that of existing f-w method.

• Journal of the Korean Geotechnical Society
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• v.32 no.7
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• pp.35-45
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• 2016

Estimation of vertical bearing capacity is critical in the design of bucket foundation used to support offshore structure. Empirical formula and closed form solutions for bucket foundations in uniform sand or clay profiles have been extensively studied. However, the vertical bearing capacity of bucket foundations in alternating layers of sand overlying clay is not well defined. We performed a series of two-dimensional axisymmetric finite element analyses on bucket foundations in sand overlying clay soil, using elasto-plastic soil model. The load transfer mechanism is investigated for various conditions. Performing the parametric study for the friction angles, undrained shear strengths, thickness of sand layer, and aspect ratios of foundation, we present the predictive charts for determining the vertical bearing capacities of bucket foundations in sand overlying clay layer. In addition, after comparing with the finite element analysis results, it is found that linear interpolation between the design charts give acceptable values in these ranges of parameters.

• Geotechnical Engineering
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• v.9 no.1
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• pp.31-44
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• 1993

Model tests in calibration chamber with open -ended steel pipe pile have been performed in sand deposit to clarify effect of soil plug on bearing capacity, load transfer mechanisms in soil plug, and behavior of soil plug under dynamic and static conditions. Model piles were devised so that bearing capacity of open -ended pile could be measured separately into outside skin friction, inside skin friction due to soil plug -pile interaction and end bearing force on the section of steel pipe pile. It may be concluded, form the test results, that the plugging level of open -ended pile is more correctily defined by specific recovery ratio, y, rather than by plug length ratio, PLR, and the major part of inside skin friction is generated within the range of three times as long as the inner diameter of the pile from the pile tip. The ratio of inside skin friction to total bearing capacity is much larger than that of outside skin friction to total bearing capacity. Therefore, the bearing capacity of pile could not be well predicted, unless the inside skin friction is properly taken into account.

• Korean Journal of Plant Tissue Culture
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• v.21 no.4
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• pp.233-237
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• 1994

Plant regeneration system via somatic embryogenesis in leaf explant cultures of Gentiana scabra var. buergeri has been established. Leaf segments formed calli when cultured on MS medium supplemented with 0.5 mg/L 2,4-D and 2 mg/L BAP After transferred to SH medium supplemented with 0.5 mg/L 2,4-D, 2 mg/L CPA and 0.5 mg/L kinetin, the callus became embryogenic. The embryogenic callus was subcultured every 3 to 4 weeks. Upon transfer onto SH basal medium the embryogenic callus gave rise to numerous somatic embryos, which subsequently developed into plantlets. The regenerated plants were potted in an artificial soil with mixture (peatmoss : pearlite : vermiculite : 2 : 1 : 1) and transplanted to the soil after kept under a high humidity for two weeks. A total of 78 plants out of 105 regenerated plants survived in the soil. Phenotypic variations in height, number of stems and the flowering time were observed in tile regenerated plants. Cytogenetical analyses showed no chromosomal variation.

• Structural Engineering and Mechanics
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• v.61 no.2
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• pp.245-253
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• 2017

The increasing lack of good quality soils allowing the development of roadway, motorway, or railway networks, as well as large scale industrial facilities, necessitates the use of reinforcement techniques. Their aim is the improvement of the global performance of compressible soils, both in terms of settlement reduction and increase of the load bearing capacity. Among the various available techniques, the improvement of soils by incorporating vertical stiff piles appears to be a particularly appropriate solution, since it is easy to implement and does not require any substitution of significant soft soil volumes. The technique consists in driving a group of regularly spaced piles through a soft soil layer down to an underlying competent substratum. The surface load being thus transferred to this substratum by means of those reinforcing piles, which illustrates the case of a piled embankment. The differential settlements at the base of the embankment between the soft soil and the stiff piles lead to an "arching effect" in the embankment due to shearing mechanisms. This effect, which can be accentuated by the use of large pile caps, allows partial load transfer onto the pile, as well as surface settlement reduction, thus ensuring that the surface structure works properly. A technique for producing rigid piles has been developed to achieve in a single operation a rigid circular pile associated with a cone shaped head reversed on the place of a rigid circular pile. This technique has been used with success in a pile-supported road near Bourgoin-Jallieu (France). In this article, a numerical study based on this real case is proposed to highlight the functioning mode of this new technique in the case of industrial slabs.

• Journal of Environmental Science International
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• v.14 no.2
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• pp.185-192
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• 2005

The concentration of heavy metal were studied for the estimation of quality in herbal medicines which is Bupleuri Radix, Paeoniae Radix, Dioscoreae Rhizoma and Astragali Radix in products of north Gyeongbuk area Also, we collected soils from several area in Gyeongbuk, and determined heavy metal concentration of soils by ICP. We compared with herbal medicines in products of Gyeongbuk and their soils. The average levels of heavy metal of herbal medicines in Gyeongbuk area are as follows: Mercury is 0.037mg/kg, Chromium is 0.093 mg/kg, Nickel is 0.108mg/kg, Copper is 0.475mg/kg, Zinc is 3.14mg/kg, Manganese is 1.52mg/kg, Iron is 7,83mg/kg, and Cadmium, Lead and Arsenic is not detected. It was very lower in concentrations than those of average Korea area. For the heavy metals contents of Gyeongbuk area, in Gong Jung Ri, represented the higher level, it may be due to a near the road. The Cd contents in soil was not a wide difference. For the As and Pb contents in soil, Song Sa Ri (Bupleuri Radix) represented the higher level(0.68mg/kg, 1523mg/kg). Correlation coefficients of heavy metal contents in cultured herbal medicines and their soils did not give reproducible results. But the degree of correlation between a few heavy metal contents of Dioscoreae Rhizoma and their soil showed the good transfer from the soil.