• Structural Engineering and Mechanics
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• v.78 no.1
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• pp.1-13
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• 2021

In this study, the porothermoelastic problem with the effect of the magnetic field and initial stress was investigated. We applied normal mode analysis to solve the resulting non-dimensional coupled equations. Numerical results for the displacements, temperature distribution, pore pressure, stresses, induced electric field and induced magnetic field distributions are presented graphically and discussed. The medium deformed because of thermal shock and due to the application of the magnetic field, there result an induced magnetic and an induced electric field in the medium. Numerical analyses are given graphically on the square (2D) and cubic (3D) domains to illustrate the effects of the porosity parameter, magnetic field and initial stress parameter on the physical variables.

• Analytical Science and Technology
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• v.19 no.3
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• pp.226-238
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• 2006

The electroplating of the Ag ions from aqueous solution on activated porous carbons was investigated over a wide range of plating time. The adsorption capacities of Ag metallic carbons were associated with their internal porosity and were related to physical properties such as surface area and pore size distribution. And, surface morphologies and quantitative analysis for the metal supported carbons are investigated by scanning electron microscopy (SEM) and energy disperse X-ray (EDX) measurements to explain the changes in adsorption properties. It is considered that the pH is an very important factor at the reason of water pollutant with increasing acidity in industrial field. The results of ICP-AES analysis showed that the residual concentration of Ag ions decreased with an increasing electroplating time. The metallic Ag-activated porous carbons electroplated showed microbicidal effects and strong antibacterial activity against six kinds of strains that were used. Finally, we confirmed that the presence of the electrolytic plated Ag-activated porous carbons is a determining factor in the HCl removal by chemical reaction, clarifying the surface chemical behavior.

• Journal of the Korean GEO-environmental Society
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• v.16 no.1
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• pp.45-53
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• 2015

This study has obtained Soil Water Retention Curve (SWRC) of the unsaturated soil from the volumetric pressure plate extractor test and the triaxial compression tests was also conducted. By using the rainfall data measured in the site the seepage analysis of unsteady flow was performed with the program of SEEP/W in Geostudio 2007 and stability of the slope was analyzed with SLOPE/W program. Results of analyses show that shear strength of the unsaturated soil increases with the increase of matric suction. And it was also found that the net volumetric stress and the apparent cohesion increased with the matric suction. The seepage analysis of rainfall represents that the increasing rate of negative pore pressure at the zone of large negative pore pressure is appeared to be high even though lower rainfall intensity, but this tendency declines with ground depth. The stability analysis of slope was carried out for the actual plane of failure with the data representing the field condition. The factor of safety thus calculated was about unity (1.0) or just below, which means that the adopted method of analysis is in good agreement with the field condition.

• Journal of the Korean Geotechnical Society
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• v.34 no.3
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• pp.29-41
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• 2018

In the case of the enlargement levee on the soft foundation, the existing levee and the enlargement levee connection can be damaged due to heterogeneous subsidence such as differential settlement at the joint of the box culvert passing through the levee. This study selected the downstream region of the Geum River and then confirmed the influence of the piping possibility on the levee by performing a 2D seepage analysis and analyzing the seepage tendency according to the position of the box culvert's gate. As a result, the flow velocity and the hydraulic gradient are larger in the upper breakage than the lower breakage, and the upper leak was more vulnerable to the piping than the lower leak. If leaks occur in the gate located on the riverside land, the risk of piping is increased when the water level rises and is maintained highly. In the case of the gate located on the inland, it could be predicted that the leakage could damage the stability of levee by increasing the water pressure inside the levee. As a result, if leakage occurs at any position in the box culvert, the pore water pressure is increased or decreased compared with the case when no leakage occurs. Therefore, if the pore water pressure is drastically reduced or increased compared with the normal case, leakage may occur. However, the result of this study is based on a 2D seepage analysis, and it is likely to be different from actual cases. Therefore, more detailed analysis by 3D analysis is recommended.

• Journal of the Korean Geotechnical Society
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• v.32 no.9
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• pp.37-50
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• 2016

Gravel compaction pile (GCP) is widely used as it increases the bearing capacity of soft ground and reduces the consolidation settlement. Stress concentration ratio for GCP design is dependent on the area replacement, surcharge pressure and depth. However, a range of stress concentration ratio obtained through field, laboratory experiments and numerical analysis is large. Little study has been done on the stress concentration ratio for the mixing ratio of gravel and sand. The main objective of the study is to evaluate the stress concentration ratio for both area replacement ratio and mixing ratio through literature review and numerical analysis. Numerical analysis using the finite element program ABAQUS 6.12-4 has been performed for the composite ground with GCP. The excess pore water pressure and stress concentration ratio of composite ground have been analyzed for both the area replacement ratio and the mixing ratio. Based on the previous research results, a range of stress concentration ratio obtained from the field tests, laboratory tests, numerical analysis on the GCP studies is found to be 1.7-3.2, 2.0-7.5 and 2.0-6.5, respectively. Based on the numerical analysis results, as the area replacement ratio increases, the stress concentration ratio increases up to 30% and then decreases at 40%. Also, the stress concentration ratio tends to increase up to 70:30 and then to decrease after 60:40.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.955-962
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• 2008

This study concerns the effect of drainage in reinforced soil on its stability during rainfall. A series of finite-element analysis based transient seepage analysis were performed on a number of cases with different drainage conditions in terms of layers of geotextiles installed in the reinforced zone. The results were then coupled with the limit-equilibrium slope stability analysis to investigate the variation of global stability factor of safety with rainfall infiltration into the reinforced wall. The results were thoroughly analyzed to get insight into the mechanism of pore water pressure reduction effect of the geotextile and into its effect on overall slope stability. It is shown that layers of geotextile installed in the reinforced zone can prevent decrease in suction in the reinforced zone during rainfall, thereby reducing potential risk of decreasing shear strength of the reinforced zone. Practical implications of the findings were discussed.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.3
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• pp.107-115
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• 2003

This paper deals with the effect of the auxiliary pole core in the automotive starter motor on its characteristics. This motor is excited by the permanent magnet and has auxiliary pole core in the stator. The auxiliary pole core is a device to increase the effective flux to obtain the starling torque and prevent the demagnetization of the permanent magnet from the starting current. It Is important to design the auxiliary pore core. And overhang structure causes the electromagnetic phenomenon of 3-dimensional flux Path. Therefore. the characteristic analysis is achieved by the 2-dimensional Finite Element Method (FEM) with the compensated model and the 3-dimensional Equivalent Magnet Circuit Network (3D EMCN). The mechanical loss and the brush and coil resistance are separated from the various experiment of the tested motor, and then these factor are reflected on the analysis results. The validity of the proposed analysis method is verified by comparing the experimental and analysis results. The effects of the design parameters related to the auxiliary pole cote on the motor performance are analyzed by the proposed method.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.1
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• pp.1-11
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• 2017

Seismic risk analysis was performed based on the total stress and effective stress of caisson type quay wall and pier type quay wall. In order to consider the effective stress effect, the pore pressure of the ground was distributed, using Byrne(1991) simple formula to estimate parameter and applied to the finn model. Through the results of seismic risk analysis according to the total stress and effective stress analysis method, the necessity of effective stress analysis in the seismic design of the quay wall installed on the soft ground was confirmed.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.806-813
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• 2008

In this research, mainly research about the structural and functional stability of sea dyke with variation of seepage condition after final closure. The piezometric head (water head in embankment) monitoring system was installed at two representative final closure section. The dredged fine sand filling condition was evaluated by in-situ test results. Also, the numerical analysis was performed to determine the permeability of bottom protection layer filled with dredged fine sand by monitoring results. According to numerical back analysis results, the coefficient of permeability of bottom protection section of is $7.6{\times}10^{-6}$ m/sec. These results are noted that the bottom protection layer of sea dyke was strong and intensively filled with dredged sand. Also, based on the seepage analysis, the seepage flux of this sea dyke was calculated about $2.42m^3$/day/m which is 29% decreased value compare with adjacent sea dyke.

• Geomechanics and Engineering
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• v.38 no.2
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• pp.165-177
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• 2024

Liquefaction phenomenon refers to a phenomenon in which excess pore water pressure occurs when a dynamic load such as an earthquake is rapidly applied to a loose sandy soil ground where the ground is saturated, and the ground loses effective stress and becomes liquid. The laboratory repetition test for liquefaction evaluation can be performed through a repeated triaxial compression test and a repeated shear test. In this regard, this study attempted to evaluate the effects of the relative density of sand on the liquefaction resistance strength according to particle size distribution using repeated triaxial compression tests, and additional experimental verification using numerical analysis was conducted to overcome the limitations of experimental equipment. As a result of the experiment, it was confirmed that the liquefaction resistance strength increased as the relative density increased regardless of the classification of soil, and the liquefaction resistance strength of the SP sample close to SW was quite high. As a result of numerical analysis, it was confirmed that the liquefaction resistance strength increased as the confining pressure increased under the same relative density, and the liquefaction resistance strength did not decrease below a certain limit even though the confining pressure was significantly reduced at a relatively low relative density. This is judged to be due to a change in confining pressure according to the depth of the ground. As a result of analyzing the liquefaction resistance strength according to the frequency range, it was confirmed that there was no significant difference from the laboratory experiment results in the basic range of 0.1 to 1.0 Hz.