• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.4
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• pp.323-331
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• 2008

Digital close-range photogrammetric technique can measure and describe 3D geometric form from 2D image. This technique is a growing applicability in the field of sciences. Nevertheless, civil and mechanical field, which need measurements as precise as possible, use expensive measuring instruments in general. In addition there are occasions for analysis by means of visual method, since appropriate measuring instruments have been not yet available. This study therefore developed digital close-range photogrammetric technique with a movable orientation board to quickly measure deformation before and after destruction from simulated ground model of reinforced-soil wall. Then the results are compared with the measurements obtained using digital theodolite.

• Journal of Korean Port Research
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• v.14 no.4
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• pp.463-473
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• 2000

Reinforcement with geotextiles have been used in the foundation soil to enhance the resistance of embankments to avoid failure through excessive deformation or shear in the foundation. It is improtant to know the amount of the strain and the displacement of buried geotextiles for the verification of the reinforcement behaviour. Full scale trial constructions were performed to check the deformational characteristics of the polyester(PET) mat which was used for the embankment reinforcement. Many instrumentation equipments including surface settlement plates, profile gauges and inclinometer casings were installed to observe the behaviour of the soft ground due to the soil embankment. 60 electrical resistance strain gauges and 9 vibrating wire LVDTs were installed 세 measure the deformation of the polyester mat. Results of various tests and geotextile, waterproofing and protection from the hazard environments were introduced. The proposed instrumentation method was effective for the monitoring or the geotextile behaviour. The direct attachment of electrical resistance strain gauges on the gertextile mat was able to measure small changes of the strain of geotextiles. At the end of the 5 month monitoring, 54 of 60 (93%) strain gauges and 7 of 9 (78%) displacement transducers survived all perils of the compaction impacts and the humidity. And the tensile strain of grotextiles increased as the ground displacement became larger. Though the observed strain of mats under the 3m high embankment load was less than 1%, the magnitudes of the strain according to the mat spreading method were different from each other.

• Journal of Mechanical Science and Technology
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• v.15 no.6
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• pp.764-775
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• 2001

Oscillartory thermocapillary flow of high Prandtl number fluids in the half-zone configuration is investigated. Based on experimental observations, one oscillation cycle consists of an active period where the surface flow is strong and the hot corner region is extended and a slow period where the opposite occurs. It is found that during oscillations the deformation of free surface plays an important role and a surface deformation parameter S correlates the experimental data well on the onset of oscillations. A scaling analysis is performed to analyze the basic steady flow in the parametric ranges of previous ground-based experiments and shows that the flow is viscous dominant and is mainly driven in the hot corner. The predicted scaling laws agree well with the numerical results. It is postulated that the oscillations are caused by a time lag between the surface and return flows. A deformation parameter S represents the response time of the return flow to the surface flow.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.868-872
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• 1997

The thermal deformation of a workpiece during grinding is one of the most important factors that affect a flatness of a grinding surface. The heat generated in one-pass surface grinding causes the convex deformation of a workpiece. Therefore, the ground surface represents a conacve profile. In the analysis a simple model of the temperature distribution,based on the result of a finite element method, is applied. The analyzed results are compared with experimental results in surface grinding. The main results obtained are as follows; (1) The temperature distibution of a workpiece by FEM is comparatively in good agreement with the experimental results. (2) The bending moment by generated heat cause a convex deformation of the workpiece and it reads to a concave profile of the grinding surface.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.2
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• pp.67-78
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• 1994

This is a fundamental study aiming at scrutinizing the effect of reinforcement and deformation characteristics of soft clayey foundation improved by vanous technical treatments. Among many methods proposed thus far, geotextile was selected for the purpose of improvement of the model soil foundation on which plate loading test was subsequently performed. Loading test has been carried out with the variation of the location and number of covering layers of geotextile, and actual values for ground deformation and geotextile effect were secured. As for technique on deformation analysis, elasto-plastic model for soil, elastic model for sand, and beam theory for geotextile were coupled with satisfactory results between observed and numerical values.

• Journal of the Korean Society of Safety
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• v.13 no.2
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• pp.54-64
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• 1998

This study was initiated to examine the stress and deformation characteristics of the pipelines which were subjected to various environmental conditions in order to confirm their integrity. As the part of them, this paper presents the analysis results for the effect of ground subsidence combined with main loads on buried natural gas pipelines. The ground subsidence which can occur for buried gas pipeline has been classified to the three cases. Finite element method was used to analyze the effect of ground subsidences on pipeline of 26 inch(0.660 m) and 30 inch(0.762 m) diameter used as high pressure ($70 kg_f/cm^2(6.86 MPa)$) main pipelines of KOGAS. This paper shows the result of stress analysis for the pipelines subjected to those three case ground subsidence. Comparing these results with safety criterion of KOGAS(0.9 $\sigma_y$), maximum allowable settlement and loads have been calculated.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.108-117
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• 2004

Dynamic analysis method is Presented for analyzing rectangular liquid storage structures excited by horizontal and vertical ground motions. The irrotational motion of invicid and incompressible ideal fluid in rigid rectangular liquid storage structures subjected to horizontal and vertical ground motions and the motion of fluid induced by structural deformation are expressed by analytic solutions. Analysis methods are obtained by applying analytic solutions of the fluid motion to finite element equation of the structural motion. The fluid-structure interaction effect is reflected into the coupled equation as added fluid mass matrix. The free surface sloshing motion, hydrodynamic pressure acting on the wall and structural behavior due to horizontal and vertical ground motions are obtained by the presented method.

• Geomechanics and Engineering
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• v.33 no.2
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• pp.195-202
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• 2023

In this study, the ground settlement in backside of retaining wall and the behavior of the retaining wall were analyzed according to the method of groundwater drawdown due to excavation by using two-dimensional(2D) finite element analysis. Numerical analysis was performed by applying 1) fixed groundwater level, 2) constant groundwater drawdown, and 3) transient groundwater drawdown. In addition, the behavior of the retaining wall according to the initial groundwater level, ground conditions, and surcharge pressure in backside of retaining wall was evaluated. Based on the numerical analysis results, it was confirmed that when the groundwater level is at 0.1H from the ground surface (H: Excavation soil height), the wall displacement and ground settlement are not affected by the method of groundwater drawdown, regardless of soil conditions (dense or loose) and surcharge pressure. On the other hand, when the groundwater level is at 0.5H from the ground surface, the method of groundwater drawdown was found to have a significant effect on wall displacement and ground settlement. In this case, the difference in ground settlement presents by up to 4 times depending on the method of groundwater drawdown, and the surcharge load could increase the ground settlement by up to 1.5 times.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.247-254
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• 2000

In this study, the reinforcing effect of micropile for weathered rock is analysed by laboratory model tests. Especially, the effect of the number, the surface roughness, and length of micropile are focused. The results of tests are as follows: $\circled1$ The deformation modulus of reinforced ground is less than equivalent deformation modulus, and $\circled2$ Increasing effect of unconfined compressive strength is not large as times as increasing the number of micropile.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.69-76
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• 1999

Because of the limited land in Korea most of the projects require large-scale reclamation. The hydraulic-filled soil deposits are usually loose and susceptible to be liquified during earthquake. The dynamic deformation characteristics which expressed by shear modulus and damping ratio are important to analyze the earthquake ground motion. In this paper resonant column tests were performed on five hydraulic filled soil in Korea and the deformational characteristics at both small and medium strains were investigated. The coefficients in the Hardin equation to predict the representative maximum shear modulus and modulus reduction cure are also proposed.