• Journal of the Korean Geotechnical Society
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• v.38 no.11
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• pp.107-118
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• 2022

The social need for stable hydrogen storage technologies that respond to the increasing demand for hydrogen energy is increasing. Among them, underground hydrogen storage is recognized as the most economical and reasonable storage method because of its vast hydrogen storage capacity. In Korea, low-depth hydrogen storage using artificial protective structures is being considered. Further, establishing corresponding safety standards and ground stability evaluation is becoming essential. This study evaluated the hydro-mechanical behavior of the ground during a hydrogen gas leak from a low-depth underground hydrogen storage facility through the HM coupled analysis model. The predictive reliability of the simulation model was verified through benchmark experiments. A parameter study was performed using a metamodel to analyze the sensitivity of factors affecting the surface uplift caused by the upward infiltration of high-pressure hydrogen gas. Accordingly, it was confirmed that the elastic modulus of the ground was the largest. The simulation results are considered to be valuable primary data for evaluating the complex analysis of hydrogen gas explosions as well as hydrogen gas leaks in the future.

• Journal of the Korean Geotechnical Society
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• v.20 no.8
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• pp.159-166
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• 2004

In this study, experiments on the SWCC were performed in order to find out the characteristics of unsaturated soil and to analyze the stability of unsaturated weathered slopes with rainfall-induced wetting. Several soil types classified by mixture portion of clay (CH) in the weathered soil (SW) were used in experimental tests. To achieve the SWCC, the filter paper method was used on SW with varying clay contents. A tensiometer test was used for measuring wetting front suction of the soils in a laboratory with varying relative densities. Based on the experimental results, it is shown that the wetting front suction increases as clay contest of mixture soil increases : in particular, the wetting front suction increases sharply as the clay contents increase. It is also found that wetting front suction affects the initial wetting band depth and stability of the slope.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.5
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• pp.331-338
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• 2020

In this study, the characteristic of a 3-D micro-woven material, which is one of the newly developed periodic open-cell structure, is analyzed through various computational simulations. To increase the accuracy of the numerical simulations, the distance between each directional wire is parameterized using six design variables, and its model geometry is precisely discretized using tetrahedron elements. Using the improved computational model, the material properties of the mechanical, thermal, and fluidic behavior are investigated using commercial software and compared with the previous experimental results. By changing the space between the x- and y-directional wires, a parametric test is performed to determine the tendency of the change in the material properties. In addition, the correlation between two different material properties is investigated using the Ashby chart. The result can further be used in determining the optimal pattern and wire spacing in 3-D micro-woven materials.

• Geotechnical Engineering
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• v.8 no.2
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• pp.81-96
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• 1992

This paper dealt with the influence of experimental error generated inevitably during performing experiments on the granular soil behaviour analysis selecting Lade's Single Work-Hardening constitutive model. Several isotropic compression-expansion tests and a series of drained conventional triaxial tests with various confining pressures for Baekma river sands were performed and the values of parameters for the above model were determined using computer program developed for this study based on regression analysis. By finding the range of the upper and lower bound for deviator stress and volumetric strain versus axial strain dependant on the increase and decrease of the standard deviation from mean value of parameters, sensitivities of all the parameters were examined. Practical use of program to determine the parameters and capability to predict the behaviour of granular soil by Lade's Single Work -Hardening model verified.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.282-287
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• 2019

본 연구의 목적은 음파를 이용하는 유속계로부터 관측된 후방산란강도와 실측된 부유사농도의 상관관계를 해석하여, 두 인자 사이의 관련 매개변수를 정량적으로 산정하고 관계식을 도출하는데 있다. 이를 위해 층별 유속계인 Aquadopp Profiler를 사용하여 사질 퇴적물 및 고령토 부유퇴적물 관측센서 검보정 챔버 실험을 수행하였다. 두 인자의 상관관계는 선형회귀분석을 통해 해석하였으며 그 결과로 도출된 접합곡선의 기울기는 각각 안목 A1 이 2.065, 안목 A2가 1.576, 고령토시료일 때 2.588의 값을 갖는데 이러한 차이는 시료 특성으로 설명될 수 있다. 서로 다른 입경을 갖는 시료는 후방산란 민감도에 차이가 있으며 이러한 영향으로 두 시료에서 산정된 계수 값에 차이가 발생한다. 본 연구를 통하여 도출된 측정 결과들은 후방산란강도에 미치는 수층 부유입자들의 영향이 매우 큼을 잘 보여준다. 일반적으로 수층 부유입자는 저면 퇴적물이 부유된 것으로 간주될 수 있으며, 또한 저면 퇴적물은 각 해역별로 site-specific 하다고 할 수 있다.

• Journal of the Korean Society for Railway
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• v.14 no.2
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• pp.151-159
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• 2011

This study performed an experimental study for air-tightness performance evaluation of concrete tube structures with joints. The test specimens consist of a continuous concrete tube, a concrete tube with a joint in the middle, and a segmented concrete tube. The test is performed in such a way that the inner pressure of the tube is dropped down to 0.1atm and the increase of the pressure is monitored with time. An equivalent air permeability is then calculated based on the test results. The results show that, as expected, a structure with more joints or bonds tends to be less air-tight. A sensitivity study shows that the system air-tightness performance level becomes higher as either the diameter or the thickness of the tube increases. Moreover, the increase in the diameter or the thickness of the tube makes an effort to enhance the air-tightness more effective.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2A
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• pp.371-382
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• 2006

A buffeting analysis is utilized for the estimation of aerodynamic vulnerability of a cable-stayed bridge due to upcoming wind turbulences. The buffeting analysis requires several input parameters such as structural parameters, aerodynamic parameters, and aero-elastic parameters. This study is motivated to estimate the sensitivity of these parameters on buffeting responses. The Seohae bridge is selected as an example bridge. The investigated parameters consist of the inclination of lift and drag coefficient of stiffening girder section, exponential decay factors of span-wise distributed wind turbulences, roughness length, spectra of wind velocity fluctuation, and structural damping. The buffeting response showed high dependency on the input parameters. As conclusions, the importance of parameter selection is emphasized. A further study is also proposed for more general conclusions.

• Journal of the Korean Geotechnical Society
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• v.31 no.12
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• pp.5-15
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• 2015

The GCP (Granular Compaction Pile) for the improvement objective of soft ground has been frequently studied. However, these studies were the results deduced on the basis of the numerical analysis and the laboratory model tests, and there was no study method to apply the effects of the bulging failure of a flexible pile. In this study, the sensitivity of the load-settlement curves of the uniform and the tapered GCP dependant on the geotechnical parameters estimated from N value of standard penetration test (SPT) was analyzed. It was estimated reasonably that, in the very soft clay soil (N=3 or less), elastic modulus was 700~2000 kPa and Poisson's ratio was 0.40~0.48.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.610-610
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• 2012

한강하구는 국가하천인 한강, 한강의 1지류인 임진강과 북한 황해도의 예성강이 만나 한강하류 수역을 형성하여 서해 중부해역과 합류하여 매우 복잡한 수리학적 특성을 지닌다. 또한 한강하구의 경우 교량, 수중보 등의 하천 구조물이 설치되어 있다. 수리학은 크게 수위와 관계되는 현상, 하상변화와 관계되는 현상, 외부 환경과 관계되는 현상으로 살펴 볼 수 있다(최계운, 2005). 하천구조물이 설치됨에 따라 구조물 주변에서 국부적으로 수위가 상승되거나 유속이 변화, 세굴현상 등의 하상 변화, 구조물 설치에 따른 생태계의 단절 현상 등 수리학적 현상에 영향을 미치게 된다. 한강하구는 이러한 복잡한 흐름현상에 더해 군사적으로 민감한 지역의 특성으로 현장의 접근성에 한계가 있어 이 지역의 연구조사는 더욱 어렵다. 그간 한강하구의 흐름 현상을 규명하기 위한 연구 방법으로 수치모의를 통한 다양한 연구가 진행되어 왔다. 수리학적 흐름 현상을 계산하기 위한 필수 조건인 하류경계조건 설정에도 어려움이 수반된다. 이 때문에 한강의 수리학적 수치모의 실험에 관한 연구들은 한강하구의 얕은 수심과 해석의 공간적 범위를 소홀히 하고, 공릉천 합류부를 기준으로 하류지점에 대해서는 인천 조위관측소의 조위자료를 사용하거나 하천정비기본계획상의 기점수위를 일괄적으로 적용하여 지점에 따른 수위의 차이를 적용하지 못하는 한계를 지닌다. 따라서 본 연구에서는 남북접경지역 접근의 어려움으로 인하여 발생되는 한강하구 흐름해석의 불확실성을 명확히 하기 위한 방안으로 한강하구지역에 해당 군부대와 군사정전위원회의 출입허가 승인을 얻어 현장조사를 실시하였다. 사전조사를 통하여 성동교, 대산교, 공릉천, 화도돈대, 철곶돈대 전방 수변, 애기봉전망대 전방 수변을 조사 지점으로 선정하였다. 기존 연구에서는 한강하구의 공릉천 합류부 지점을 하류경계조건으로 채택하고 있으나, 현장조사를 통하여 얻을 자료를 분석한 결과 공릉천 합류부 지점의 수위는 강우발생에 대한 하천의 영향을 받는 것으로 나타나 하류경계조건으로 적정하지 않은 것으로 판단되었으며, 공릉천보다 하류지역에 위치한 지역에 대하여 하류경계조건으로 적정한 지역을 찾을 수 있었다. 수치해석 시에는 공간적 범위와 연구의 목적을 고려하여 각 지점의 실제 관측 자료를 활용한 경계조건을 사용하는 것이 적합한 것으로 판단되며 보다 많은 현장조사와 특성분석을 통한 정확한 경계조건의 구축이 필요할 것으로 사료된다.

• Journal of the Korean GEO-environmental Society
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• v.12 no.9
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• pp.35-45
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• 2011

This paper is to analyze the behaviors of tunnel support by TDR(Time Domain Reflectometry) sensor using electrical pulse. To analysis the behaviors of tunnel support, Copper tape as sensing materials was studied for on-site installation. Copper tape to the top of the glass tape, foam tape, and shielding the lower part was used electromagnetic shield sheet. For a high sensitivity to load and fill out the measurement noise emissions has been developed for the production of materials. This sensing material through the tunnel model tests for the change by surcharge load in TDR data were analyzed. Varing stiffness and support of conditions were determined the change of TDR data through PVC pipe tunnel section model tests. By comparing TDR data and finite element analysis, the behaviors of the tunnel support materials were analyzed qualitatively.