• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.2C
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• pp.49-60
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• 2012

In this study, the behaviors of friction pile groups are investigated using 3D finite element (FE) analysis. The emphasis was quantifying on the shear load transfer (f-w) characteristics of pile groups and the shaft group effects. A framework for determining the f-w curve is proposed based on both theoretical analysis and field load test database. Through comparisons with case histories and FE results, it is shown that the proposed f-w curve is capable of predicting the behavior of a friction pile in deep soft clay. Additionally, a numerical analysis that takes into account the group efficiency factors were performed for major parameter on group pile-soil interaction, such as the pile spacing, pile arrangement, soil condition, and location of pile cap. Based on these results, the shaft group efficiency factors were also proposed.

• Journal of Korea Soil Environment Society
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• v.2 no.3
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• pp.31-38
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• 1997

Temporal and spatial comparisons of acid mine drainage contaminated waters are difficult because of the complex physico-chemical nature of the pollutant. In the present study, an acid mine drainage index has been developed and evaluated for the assessment of surface waters. AMD index is calculated using a modified arithmetic weighted index using seven parameters which are most indicative of AMD contamination, i. e. pH value, sulphate, iron, zinc, aluminum, copper and manganese. Weighting is used to express the relative indicator value of each parameter. The proposed AMD index is used to quantify contamination from acid mine drainage over ten different old mine sites and assess the degree of impact on surface on surface waters. As a result of AMD evaluation, the Sukbong Mine located near the Moonkyung province showed lowest AMD value indicating the worst acid mine drainage quality. In overall, Youngdong mine sites showed higher contaimination compared to the other mine sites including Youngsuh, Choongbu, Suhbu and Nambu area.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.311-314
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• 2006

This paper concerns about total dynamic analysis of integrated mining system. This system consists of vertical steel pipe, intermediate buffer station, flexible pipe and self-propelled miner. The self-propelled miner and buffer are assumed as rigid-body of 6-dof. Discrete models of vertical steel pipe and flexible pipe are adopted, which are obtained by means of lumped-parameter method. The motion of mining vessel is not considered. Instead, the motion of mining vessel is taken into account in form of various boundary conditions (e.g. forced excitation in slow motion and/or fast oscillation and so on). A terramechanics model of extremely soft cohesive soil is applied to the self-propelled miner. The hydrodynamic forces and moments are included in the dynamic models of vehicle and lifting pipe system. Hinged and fixed constraints are used to define the connections between sub-systems (vertical steel pipe, buffer, flexible pipe, miner). Equations of motion of the coupled model are derived with respect to the each local coordinates system. Four Euler parameters are used to express the orientations of the sub-systems. To solve the equations of motion of the total dynamic model, an incremental-iterative formulation is employed. Newmark-b method is used for time-domain integration. The total dynamic responses of integrated mining system are investigated.

• Atmosphere
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• v.20 no.3
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• pp.273-286
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• 2010

The northeast part of China(hereafter Manchuria) is one of Asian dust source regions along with Gobi, Inner Mongolia and Loess Plateau. In this study, a geographical survey over the area was carried out to determine its soil characteristics in June 2009. It revealed that some parts of the area, especially near Keerchin desert, consist of alkali clay soil mixed up with sand. Manchuria, where is a vast cornfield, can be a potential source region of Asian dust from fall to following spring after harvesting. The frequency of Asian dust over the region from 1996 to 2009 was examined using 3-hourly GTS SYNOP data and it showed that the occurrence of Asian dust over the region is high in the springtime. It was also revealed that snow cover is the key parameter affecting on the frequency through the analysis of NCEP reanalysis data. To scrutinize the path and structure of Asian dust from Manchuria, the event on 3~4 April 2008 and 25 January 2010 were intensively investigated with regard to features of synoptic weather patterns, satellite imagery, airstream, naked eye-observations, concentrations of PM10, 2.5 and 1.0. For this case, the Asian dust from the area reached to Korea less than a day. However, the duration time of the dust in Korea was short (< 7 hours). The average of hourly PM10 reached up to $340{\mu}g/m^{3}$ at Baengnyeondo during the period. The high PM2.5 and PM1.0 concentrations were also observed at several sites in Korea, indicating that air pollutants could be transported along with the dust.

• Journal of Soil and Groundwater Environment
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• v.11 no.6
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• pp.83-91
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• 2006

Reduction kinetics and the behaviour of intermediate of three high explosives (HMX, RDX, and TNT) were studies in batch reactors using nano- or micro- size zero valent iron(nZVI or mZVI) as reducing agent. The kinetic constants normalized by the mass of iron ($k_M$) or by the surface area ($k_{SA}$) were measured and compared along with the changes in the concentrations of intermediates. Results showed that $k_M$ and $k_{SA}$ values were not suitable to fully explain the behaviour of mother compounds and reduced intermediates in the batch reactor. The concentrations of initial explosives degradation products, such as nitroso-RDXs, nitroso-HMXs, and hydroxylamino-TNTs, were higher in mZVI treated reactor than in nZVI treated reactor, whereas more reduced polar intermediates such as TAT were accumulated in the nZVI reactor. Therefore, a new parameter, which accounted for the intermediates reduction, needs to be developed.

• Journal of Soil and Groundwater Environment
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• v.12 no.1
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• pp.44-52
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• 2007

This study reviewed the overall process of application of contaminant fate and transport model as part of risk assessment. Site characterization and establishment of a conceptual model prior to establishing or selecting a appropriate model were described. Types of models, model selection guidance, and generic site conditions for model application were presented, the process of model calibration, validation, and sensitivity analysis were reviewed. Objectives of modeling should be defined before model selection, and the complexity of selected models should balance the quantity and quality of available input data with the desired model output. If model output is highly sensitive to an assumed or default value of input parameter, or fate and transport models cannot be adequately calibrated or validated, consideration should be given to other options such as using measured data or using another model.

• Journal of the Korean Geosynthetics Society
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• v.12 no.1
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• pp.63-72
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• 2013

The structural stability of fill dam largely depends on the engineering behavior of rock materials used as main zone for dam construction and it is necessary to understand well the stress-strain characteristics of fill materials as well as shear strength property. In addition, the numerical analysis of fill dam requires a thorough study for calibrating material properties and parameters of a coarse-grained soil constitutive model. In this paper, large triaxial test results for Buhang-dam fill materials are analyzed and constitutive model parameters are calibrated based on the test results. It is shown that MD constitutive model is capable to predict the stress-strain behavior of dense and loose coarse-grained soils used for Buhang-dam construction based on the comparison study between the experimental test result and numerical simulation.

• Korean Journal of Environment and Ecology
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• v.21 no.1
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• pp.22-29
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• 2007

Investigation of carabid beetles as on ecological indicator species for wetland characterization and monitoring was conducted in three types of wetlands such as emergent wetland, forested wetland, and estuary, During the investigation period, twenty-eight species belonging to twenty-two genera and three families(Carabidae, Harpalidae, Brachinidae) were identified. The diversity of carabid beetles at riverine wetland such as Woopo (H'=1.18) and Hwapo-neup (H'=1.08) were higher than in the forested wetland (H'=1.03) and estuarine (H'=0.91). Species compositions in each wetland were significantly different(${\chi}^2=1716.8$, P<0.01). Riverine wetlands differed significantly from the forested wetland. Indicator species for the wetland chose with indicator species analysis were reacted sensitively on the parameter such as soil composition, moisture of soil, and environmental change. Thus, it was consequently suggested that these indicator species may be applied for wetland characterization and monitoring of the wetland ecosystem.

• Journal of the Korean GEO-environmental Society
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• v.13 no.6
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• pp.67-72
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• 2012

Finite element method was used to compare un-piled and piled raft foundation behaviors on sandy soils in this study. The soil parameters were estimated from SPT tests of 25 boreholes. Based on these soil parameters, a finite element analysis was conducted on un-piled and piled raft foundations. For the un-piled raft, the normalized settlement parameter for raft sizes of $8m{\times}8m$ and $15m{\times}15m$ ranged from 1.02~1.15 and 0.64~0.81, respectively. The raft thickness affects differential settlement and bending moments, but has little effect on load sharing or maximum settlement. Pile spacing greatly affected the maximum settlement, the differential settlement, the bending moment in the raft, and the load shared by the piles, while the differential settlement, the maximum bending moment and the load sharing are not affected very much by increasing the pile lengths.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.157-171
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• 2009

A 151 storey super high-rise building located in an area of reclaimed land constructed over soft marine clay in Songdo, Korea is currently under design. This paper describes the design process of the foundation system of the supertall tower, which is required to support the large building vertical and lateral loads and to restrain the horizontal displacement due to wind and seismic forces. The behaviour of the foundation system due to these loads and foundation stiffness influence the design of the building super structure, displacement of the tower, as well as the raft foundation design. Therefore, the design takes in account the interactions between soil, foundation and super structure, so as to achieve a safe and efficient building performance. The site lies entirely within an area of reclamation underlain by up to 20m of soft to firm marine silty clay, which overlies residual soil and a profile of weathered rock. The nature of the foundation rock materials are highly complex and are interpreted as possible roof pendant metamorphic rocks, which within about 50m from the surface have been affected by weathering which has reduced their strength. The presence of closely spaced joints, sheared and crushed zones within the rock has resulted in deeper areas of weathering of over 80m present within the building footprint. The foundation design process described includes the initial stages of geotechnical site characterization using the results of investigation boreholes and geotechnical parameter selection, and a series of detailed two- and three-dimensional numerical analysis for the Tower foundation comprising over 172 bored piles of varying length. The effect of the overall foundation stiffness and rotation under wind and seismic load is also discussed since the foundation rotation has a direct impact on the overall displacement of the tower.