• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.05a
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• pp.11-14
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• 2000

Wastewater sludge and composted food wastes were examined as the alternatives of a landfill cover for soils to eliminate the emission of VOCs. The benefit of these alternatives is in their high sorption capacity, which is 5 to 50 times higher than natural soils. After sorption is finished, biodegradation is an important mechanism in decrease of VOCs concentration. In order to investigate appropriate VOCs degradation condition, biodegradation batch experiment is being conducted with isolated strain X9-c. Both benzene and TCE were degraded only in soil with 12%(water volume/sorbent volumn) water condition. When the water condition varied from 12 to 48% in compost, optimum water conditions of composted food waste was 36%.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.370-375
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• 2005

This paper describes a systematic way of identifying the horizontal coefficient of consolidation for clayey soil under undrained condition and silty soil under partial drained condition by applying an optimization technique to the early part of dissipation data measured from the self-boring pressuremeter strain holding test. An analytical solution developed by Randolph & Wroth (1979) was implemented in normalized form to express the build-up and dissipation of excess pore pressures around a pressuremeter as a function of the rigidity index. Horizontal coefficient of consolidation was determined by minimizing the differences between theoretical and measured excess pore pressure curves using optimization technique. It was found that the proposed optimization technique can evaluate in-situ horizontal coefficient of consolidation rationally, which is similar with that obtained from the piezocone dissipation test. Furthermore, proposed method can evaluate appropriate coefficient of consolidation for soil under partially drained condition.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.3
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• pp.76-88
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• 2000

AGNPS model is applied in this study to analyze the changes of non-point source pollutant according to AMC condition using probable rainfall. Probable rainfall of H-dam area by Gumber's extreme value distribution is computed through frequency analysis for each return period. 35 coarse grids are subdivided into 134 find grids of finite differential network to analyze peak flow soil loss quantity and nutrients of study area and the modified CN estimation equation shows good result about rainfall events-peak flow relationship. And as the consequence of estimation of soil loss quantity for each rainfall event soil loss quantity shows 120%-170% of actual soil loss quantity Regression analysis for the observed and calculated values of flow T-P AMC has an important effect on nutrients concentration of outflow and it if found that the excessive fertilization under AMC III condition may cause eutrophication by nutrients because the range of increase of outflow concentration appears relatively high.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.1
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• pp.23-27
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• 2014

Nutrient accumulation in surface soil has become a serious problem for cucumber production in greenhouse. However, still in many cases, soil management practices are only focused on maintaining crop yield, regardless of sustainability related with soil chemical properties. This study was conducted to propose a sustainable soil management practice by investigating the impact of cover crop species and nitrogen rate of fertigated solution on cucumber yield and soil chemical properties in greenhouse condition. Rye and hairy vetch were tested as a fallow cover crop, and each amount of urea (1/2, 3/4, 1 times of N fertilizer recommendations), determined by soil testing result, was supplied in fertigation plots as an additional nitrogen source. The result showed that the yield of cucumber was higher in rye treatment than control and hairy vetch treatment. In addition, rye effectively reduced EC and accumulated nutrients from the soil. Meanwhile, N concentration of fertigated solution showed no significant effect on the growth and yield of cucumber. Consequently, these results suggest that it is desirable to choose rye as a fallow catch crop for sustainable cucumber production in greenhouse.

• Korean Journal of Plant Resources
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• v.34 no.6
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• pp.608-615
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• 2021

Soil moisture control system including soil sensing and automatic water supply chain was constructed on open farmland and pot conditions. Soil moisture was controlled by the system showing over the soil moisture contents except 40% treatment. EC was gradually decreased by increasing cultivation days. On applying this system to control soil moisture, the growth and development characters of the bellflower were improved compared with control, cultivation without the automatic irrigation. Of the growth and development characters, plant height with water treatments was higher than that of control in 1st-year plants. Moreover, numbers of branch were increased by the increased soil moisture on farmland and pot condition. Capsule numbers for seed were best at 20%, 30% soil moisture treatment in 1st-year plants, and 20% to 50% treatment in 2nd-year plants. The construction of automatic soil moisture control system provide fundamental data for plant growth and development on open farmland soil condition.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.04a
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• pp.136-143
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• 2001

In this study, a numerical analysis for soil-pile interaction systems in multi-layered half planes under a forced vibration is presented. The soil-pile interaction system is divided into two parts, so called near field and far field. The near field soil using finite elements and piles using beam elements are modeled. The far field soil media is implemented using boundary elements those can automatically satisfy the condition of wave radiation. These two fields are numerically coupled by imposing displacement compatibility condition at the interface between the near field and the far field. For the verification, the forced vibration test was simulated and the response under horizontal and vertical harmonic loads at the pile cap in the layered half plane was determined. The results are compared to the theoretical and experimental results of the literatures to verify the proposed soil-pile interaction analysis formulation.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.735-738
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• 2005

The purpose of this study is the infiltration characteristics of soil cut-slope by rainfall. Stability analysis of soil cut-slopes has been conducted by limit equilibrium method on Seep/w and finite element method on Slope/w. Result is same as following. First. the hour when seepage line and groundwater in contact is proportionate from rainfall rate condition and upper natural slope gradient condition which is identical. Second, when seepage line and groundwater is contact, seepage line moves gradually at soil cut-slope surface. Finally, seepage line is formed similarly with soil cut-slope gradient. Third, when rainfall is ended, from the recording upper natural slope where the hour will pass it is stabilized

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.346-346
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• 2017

In Northern Laos, maize is cultivated in continuous cropping without fertilizer, fallowing nor any other soil conservation practice. It is expected that this inadequate management in maize cultivation will degrade soil and decrease yield. However, there is limited information about the change of soil condition and yield under continuous maize cultivation. We tried to evaluate the change of soil condition and yield under continuous maize cultivation in Northern Laos. Our study was conducted in farmer's flat and slope fields in Sainyabuli province where maize cultivation had been introduced earlier than the other provinces of Northern Laos. Our study was conducted in 21 fields in 2014, and in 19 fields in 2015. We analyzed grain yield and soil characteristic (total carbon (TC), total nitrogen (TN), available phosphorus (Av-P), exchangeable cation, pH, soil texture) at 3 places in each field. The 3 places were set at different elevation level (lower position, middle position, upper position) in slope fields. Further, the period of continuous maize cultivation and crop management practice were investigated. Then, by evaluating the relation between the period of continuous maize cultivation and yield and the soil characteristics, the effect of maize cultivation was estimated. Crop management practices were similar among the investigated fields. Maize was cultivated in rain season. Grain seed and cob were harvested on September or October, but shoot was left on the fields. No crop was cultivated during dry season. Fertilization and fallowing has never been conducted under continuous maize cultivation. On the other hand, the period of maize cultivation was different among the fields, and ranged from 2 years to 30 years. In the slope fields, as the period of continuous maize cultivation was longer, the contents of TC and TN were lower at all 3 positions, Av-P content was lower at the upper position, exchangeable potassium (Ex-K) content was lower at the middle and the upper positions. The other soil characteristics weren't related with the period of maize cultivation in the slope fields. In contrast, soil characteristics weren't related with the period of maize cultivation in the flat fields. Yield was lower as the period of maize cultivation was longer at the upper position of the slope fields. At middle position of slope fields, yield tended to be low with increase of the period of maize cultivation. In contrast, yield wasn't related with the period of continuous maize cultivation in flat fields. From the results about crop management, it was presumed that the period of maize cultivation was one of the main factors causing the difference of yield and soil characteristics among the fields. Therefore, from the result of yield and soil condition, it was considered that the continuous maize cultivation decreased soil productivity in the slope fields with decline of TC, TN, Av-P, Ex-K and yield at upper position of slope fields, and decline of TC and TN in the other positions in Sainyabuli province.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.169-174
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• 2003

Undrained triaxial tests were performed under $K_{0}$ condition for a weathered soil, which includes local measurement using LVDT. An anisotropic hardening model based on effective stress concept could predict the stress-strain relationship under $K_{0}$ condition reasonably, which makes it possible to analyze geotechnical problems for the weathered soil.

• Geomechanics and Engineering
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• v.19 no.2
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• pp.141-151
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• 2019

A novel theoretical solution is presented for created (zero initial radius) cavity expansion problem based on CamClay model and considers the effect of initial anisotropic in-situ stress and drained conditions. Here the strain of this theoretical solution is small deformation in elastic region and large deformation in plastic region. The works for cylindrical and spherical cavities expanding in drained condition from zero initial radius are investigated. Most of the conventional solutions were based on the isotropic and undrained condition, however, the initial stress state of natural soil mass is anisotropy by soil deposition history, and drained cavity expansion calculation is closer to actual engineering in permeable soil mass. Finally, the parametric study is presented in order to the engineering significance of this work.