• Journal of Soil and Groundwater Environment
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• v.19 no.3
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• pp.104-110
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• 2014

In order to study gross alpha analysis method using LSC, the efficiency tests with uranium standard materials were performed and then compared with the GPC method (US EPA 900.0 method) using 15 groundwater samples. For 15 groundwater samples, the average efficiencies of the GPC and LSC method were 7~11% and 90%, respectively. The average precisions of the GPC and LSC method were 16.16% and 6.00%, respectively. Also, The average standard deviations for 15 samples were 7.38 pCi/L and 2.95 pCi/L, respectively. The determination coefficient of the tested results by two methods was 0.9948. As a result, the LSC method tested in this study was applicable for the screening of the gross alpha and showed the advantages in the gross alpha measurement due to the simple measurement procedures.

• Journal of the Korean Geotechnical Society
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• v.38 no.1
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• pp.17-33
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• 2022

This study describes the effect of ground water table on the dynamic analysis of single piles subjected to earthquake loading. The dynamic numerical analysis was performed for different dry and saturated soils with varying the relative densities of surrounding weathered soils (SM). The test soil was a weathered soil encountered in the engineering field and bender element tests were conducted to estimate the dynamic properties of test soil. The Mohr-Coulomb model and Finn model were used for soil, dry and saturated conditions, respectively. These models validated with results of centrifuge tests. When compared with the results from the soil conditions, saturated cases showed more lateral displacement and bending moment of piles than dry cases, and this difference caused from the generation of excess porewater pressure. It means that the kinematic effect of the soil decreased as the excess pore water pressure was generated, and it was changed to the inertial behavior of the pile.

• Journal of the Korean Geotechnical Society
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• v.23 no.3
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• pp.101-109
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• 2007

In South Korea, many weathered soil slopes are composed of soil mixtures with certain amount of clay fractions in natural soil deposits. Accordingly, it is very important to analyze that effect of the fines on the stability of unsaturated soil slopes. In this study, five different soil types classified by mixture portion of fines were used and experiment on the soil-water characteristic curve tests (SWCC) using GCTS (Geotechnical Consulting and Testing Systems) pressure plate were performed in order to analyze the stability of unsaturated soil slopes. Based on the infiltration analysis which contains SWCC test result by the SEEP/W, it is shown that the increasing rate of the wetting band depth was decreased as the fines content and the relative density were increased. According to the stability analysis result of the unsaturated soil slopes through the SLOPE/W, it is found that the transition from the wetting band depth to the variation of strength parameters which affect the stability of unsaturated soil slopes appears to occur around $10\sim15%$ of clay contents in the mixtures.

• Journal of Ocean Engineering and Technology
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• v.27 no.4
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• pp.98-106
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• 2013

Seismic fragility curves for an offshore wind-turbine structure were obtained. The dynamic response of an offshore wind turbine was analyzed by considering the nonlinear behavior of layered soil and the added mass effect due to seawater. A pile-soil interaction effect was considered by using nonlinear p-y, t-z curves. In the analysis, the amplification effect of ground acceleration through layered soil was considered by applying ground motion to each of the soil layers. The vertical variation in ground motion was found by one-dimensional free-field analysis of ground soils. Fragility curves were determined by damage levels in terms of tower stress and nacelle displacements that were found from static pushover analysis of the wind-turbine structure.

• Journal of the Korean Geotechnical Society
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• v.29 no.3
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• pp.41-50
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• 2013

There always exists uncertainty which is mainly due to uncertainty of the evaluation of a geotechnical structure at a site. The uncertainty in the geotechnical analysis can be considered in the probabilistic analysis using the Monte Carlo Simulation. It needs various soil profiles which could be possible at the target site. In this study, a new method is proposed to generate soil profiles which are probable at the site. The proposed method analyzes a structure of a site and generates one dimensional soil profiles for a probabilistic analysis. Through the field application, the applicability of the prosed method was shown.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.4
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• pp.231-236
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• 2013

This study was conducted to investigate the yield response of soybean to drought stress in 1984 and 1986 at the experiment field of the National Academy of Agricultural Science using experiment plots with different soil water tension and fertilizer levels. The average yield response factor (YRF) of soybean to evapotranspiration (ET) calculated as [(Ya/Ym)/(ETa/ETm)], where Ya, average yield; Ym, maximum yield; ETa, average ET; and ETm, maximum ET, was 0.91 with the range from 0.74 to 1.16. Relationship between yield index (YI=[Ya/Ym]) and evapotranspiration index (ETI=[ETa/PET]) was $YI=0.87{\cdot}(ETI)+0.09$. Relationship between YI and the maximum soil water tension (Hmax) was $YI=1.23-0.23{\cdot}{\log}$ (Hmax). Relationship between YI and the days of drought stressed (Dr) was $YI=0.877{\cdot}{\exp}$ ($-0.01{\cdot}Dr$). The relation between YI and fertilizer level (F) was $YI=-0.21{\cdot}F2+0.36{\cdot}F+0.33$, under very serious drought condition as the maximum soil water tension was 0.3 MPa.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.3
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• pp.55-63
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• 2012

Soil properties are not random values which is represented by mean and standard deviation but show spatial correlation. Especially, soils are highly variable in their properties and rarely homogeneous. Thus, the accuracy and reliability of probabilistic analysis results is decreased when using only one random variable as design parameter. In this paper, to consider spatial variability of soil property, one-dimensional random fields of coefficient of consolidation ($C_v$) were generated based on a Karhunen-Loeve expansion. A Latin hypercube Monte Calro simulation coupled with finite difference method for Terzaghi's one dimensional consolidation theory was then used to probabilistic analysis. The results show that the failure probability is smaller when consider spatial variability of $C_v$ than not considered and the failure probability increased when the autocorrelation distance increased. Thus, the uncertainty of soil can be overestimated when spatial variability of soil property is not considered, and therefore, to perform a more accurate probabilistic analysis, spatial variability of soil property needed to be considered.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1997.04a
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• pp.257-264
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• 1997

Seismic responses of the Hualien large scale seismic test model on a layered soil site are estimated for two recorded earthquakes and the analysis results are then compared and evaluated with the recorded responses. The method adopted for the analysis is based on substructuring method using a lumped parameter model in both the frequency and time domain. the study results indicate that the proposed method can reasonably estimate the earthquake responses of a soil-structure interaction system for engineering purposes.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.3
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• pp.274-278
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• 1999

Determination of soil texture, particularly the clay fraction, is an important measurement in most researches related with soil. In this study micro-pipette method For soil particle size analysis was compared with the standard hydrometer method. Micro-pipette method can eliminate the need for bulky laboratory equipment and long settling times associated with the standard hydrometer or pipette method. In the results of this investigation, the particle size data obtained with micro-pipette method were in good agreement with those found using standard hydrometer method. And with this method one person could run analysis much larger numbers of soil sample per day than with hydrometer method in relatively small laboratory space.

• Journal of Korean Tunnelling and Underground Space Association
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• v.2 no.3
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• pp.71-81
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• 2000

For the construction of NATM tunnel, it is required a design based on the accurate soil condition from soil investigation. However, in practice, it often designs tunnels without fully understanding the condition. Especially, when soft soil comes up, or ground water breaks out suddenly on the construction, it needs to secure the stability of tunnel by appropriate reinforcing construction according to the results of measurements on field superlatively reflecting the faced situation. This report reviews the mostsuitable stability of tunnel in the construction of soft soil of tunnel by numerical analysis using FDM after re-evaluated the soil properties through back analysis using the results of measurements to simulate abruptly occurred deformation. And applying steel pipe grouting row by row on the wall and the low part of tunnel and also applying the construction method of temporary invert after excavation of the upper part of tunnel, the excavation of soft soil tunnel secured the structural stability of tunnel has been completed.