• 한국철도학회논문집
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• 제5권4호
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• pp.244-252
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• 2002

We must notice ground movement by excavation for reasonable tunnel designs. The convergence confinement method is an attempt to evaluate tunnel stability conditions by means of a mathematical model and a ground response curve. In this study, the convergence confinement method by numerical model was examined. This method don't need the basic assumptions for a mathematical model of circular tunnel shape, and hydrostatic in situ stress. Also modified ground response curve that is calculated after installing the support, is suggested, which informs us the ground movement mechanism. The ground response curve and the support reaction curve are mutually dependent. Especially the support reaction curve depends upon the ground response curve. The mechanism of tunnel must be analyzed by the interaction between support and ground. Consequently the stability of tunnel must be qualitatively investigated by a ground response curve and quantitatively adjudged by a numerical analysis for the reasonable design of tunnel.

• 항공우주기술
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• 제13권2호
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• pp.99-107
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• 2014

다목적실용위성 2호/3호 위성자료를 이용하여 지상좌표를 결정하는 방법은 Physical Model과 RFM(Rational Function Model)의 두 가지 종류가 있다. 일반적으로 사용자에게 제공되는 모델은 RFM을 기반으로 한 RPCs(Rational Function Coefficients)이며, 이때 제공되는 RPCs는 지상좌표에서 영상좌표를 계산하는 계수이다. 사용자가 정사영상을 만들 경우에는 이 계수가 유용하나, 영상에서 임의의 영상기준점에 대응하는 지상좌표를 계산하거나, 위치정확도를 확인하기는 매우 어렵다. 본 논문은 다목적실용위성에서 제공되는 RPCs를 기반으로 Inverse RPCs를 해석하는 알고리즘과 해석된 Inverse RPCs를 기반으로 지상표고를 고려한 정밀 지상좌표 해석 알고리즘을 기술하고자 한다. 또한 Inverse RPCs의 해석된 정밀지상좌표 정확도와 Physical Model과의 차이를 계산하여 정확도를 평가하고자 한다.

• 조명전기설비학회논문지
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• 제24권12호
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• pp.208-213
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• 2010

This paper deal with an analysis of the ground surface potential profiles using a hemispherical scaled-model. Because it is very difficult to draw valid conclusions concerning a general grounding problem from actual field data, scale model tests can be used to determine the ground surface potential profile around the grounding electrodes according to the configuration of grounding electrodes. In this work, a hemispherical vessel with a diameter of 1,100 [mm] was employed to simulate uniform soil and CDEGS program was employed to compare the measured and simulated results. As a result, the ground surface potential around the grounding electrode was significantly raised and the ground surface potential at the just upper point of ground electrode particularly was higher than other points. The ground surface potential of counterpoise was higher than other grounding electrodes such as mesh and grounding rods and the ground surface potential strongly depends on the frequency responses of grounding electrodes. Also the results measured with the small-sized model were in reasonably agreement with the data obtained from simulation.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.299-306
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• 2001

Crushed Stone Pile(CSP) is one of the ground improvement methods available to loose sand and clayey ground by forming compacted CSP in the weak soil layer. The effects of this method are enhancement of ground bearing capacity, reduction of settlement and prevention of lateral ground movement in cohesive layer, reduction of liquefaction potential in sandy ground. This study performs model tests in 1.0m${\times}$1.0m${\times}$1.0m and 1.5m${\times}$1.5m${\times}$l.2m model tank to observe bearing capacity of CSP treated ground. The area replacement ratio of CSP composite ground varies 20%, 30% and 40% with square grid pattern. After the composite ground was consolidated under pressure of 0.5kg/$\textrm{cm}^2$ and 1.0kg/$\textrm{cm}^2$, load tests were carried out. The results show that ultimate bearing capacity increases with area replacement ratio and the preconsolidation pressure of ground.

• Geomechanics and Engineering
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• 제30권6호
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• pp.551-564
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• 2022

Fragmenting the rock mass is considered as the most important work in open-pit mines. Ground vibration is the most hazardous issue of blasting which can cause critical damage to the surrounding structures. This paper focuses on developing an explicit model to predict the ground vibration through an multi objective evolutionary polynomial regression (MOGA-EPR). To this end, a database including 79 sets of data related to a quarry site in Malaysia were used. In addition, a gene expression programming (GEP) model and several empirical equations were employed to predict ground vibration, and their performances were then compared with the MOGA-EPR model using the mean absolute error (MAE), root mean square error (RMSE), mean (𝜇), standard deviation of the mean (𝜎), coefficient of determination (R²) and a20-index. Comparing the results, it was found that the MOGA-EPR model predicted the ground vibration more precisely than the GEP model and the empirical equations, where the MOGA-EPR scored lower MAE and RMSE, 𝜇 and 𝜎 closer to the optimum value, and higher R² and a20-index. Accordingly, the proposed MOGA-EPR model can be introduced as a useful method to predict ground vibration and has the capacity to be generalized to predict other blasting effects.

• 설비공학논문집
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• 제16권7호
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• pp.658-666
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• 2004

In this paper, a two-dimensional transient ground-coupled numerical model for slab-on-grade foundation is developed and integrated into EnergyPlus. A validation analysis is first presented to ensure that for the developed building foundation heat transfer module is properly implemented within EnergyPlus. Then, the predictions from the developed model are compared to those obtained from the simplified building foundation model currently used in EnergyPlus. The results show that the developed foundation heat transfer module accounts better for the effects of the ground thermal mass attributed to the ground than the simplified foundation model currently used in EnergyPlus.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.255-262
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• 2000

Shaking table tests were peformed to evaluate the subgrade reaction of ground according to the build-up of pore water pressure. Model pile was installed in the sand ground. The acceleration of the model ground, the pore water pressure build-up and displacement of pile were recorded by measuring devices. Subgrade reaction approach based on Winker soil model was applied to obtain the modulus of the horizontal subgrade reaction. The results of analysis show that the reduction factor of the subgrade reaction due to pore pressure increase is about 1 and the horizontal subgrade reaction of liquefied ground is not influenced by the stiffness of pile, a ground acceleration and the intial ground density.

• 한국지진공학회논문집
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• 제20권7_spc호
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• pp.537-543
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• 2016

In low to moderate seismic regions, there are limited earthquake ground motion data recorded from past earthquakes. In this regard, the Gyeongju earthquake (M=5.8)occurred on September 12, 2016 produces valuable information on ground motions. Ground motions were recorded at various recording stations located widely in Korean peninsula. Without actual recoded ground motions, it is impossible to make a ground motion prediction model. In this study, a point source model is constructed to accurately simulate ground motions recorded at different stations located on different soil conditions during the Gyeongju earthquake. Using the model, ground motions are generated at all grid locations of Korean peninsula. Each grid size has $0.1^{\circ}(latitude){\times}0.1^{\circ}(longitude)$. Then a contour hazard map is constructed using the peak ground acceleration of the simulated ground motions.

• 한국해양공학회지
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• 제20권5호
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• pp.42-48
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• 2006

This paper shows theresults of centrifuge model experiments to investigate the behavior of a replacement method in dredged and reclaimed ground. For this experimental work, centrifuge model tests were carried out to investigate the behavior of a replacement method in soft clay ground. Basic soil property tests were performed to find the mechanical properties of clay soil sampled from the southern coast of Korea, which was used for the ground material in the centrifuge model tests. The reconstituted clay ground of the model was prepared by applying reconsolidntion pressure in a 1 g condition with a specially built model container. Centrifuge model tests were carried out under the artificially accelerated gravitational level of 50 g. Replacement material of lead with a certain degree of angularity was used and placed until the settlement of the replacement material embankment reached a state of equilibrium. Vertical displacement of the replacement material was monitored during tests. The depth and shape of the replacement, especially the slope of the penetrated material and the water content of the clay ground were measured after finishing tests. Model tests for investigating the stability of an embankment after backfilling were also performed to simulate the behavior of a dike treated with replacement and backfilled with sandy material. As a result of the centrifuge model test, the behavior of the replacement, the mechanism of the replacement material being penetrated into clay ground, and the depth of the replacement were evaluated.

• Structural Engineering and Mechanics
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• 제9권2호
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• pp.141-152
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• 2000

Based on the discussion about some empirical coherency models resulted from earthquake-induced ground motion recordings at the SMART-1 array in Taiwan, and a heuristic model of the coherency function from elementary notions of stationary random process theory and a few simplifying assumptions regarding the propagation of seismic waves, a practical coherency model for spatially varying ground motions, which can be applied in aseismic analysis and design, is proposed, and the regressive coefficients are obtained using least-square fitting technique from the above recordings.