• Tunnel and Underground Space
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• v.34 no.2
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• pp.127-142
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• 2024

The robustness of a numerical method means that its computational performance is maintained under various modeling conditions. New numerical methods or codes need to be assessed for robustness through benchmark testing. The TOUGH-FLAC modeling approach has been applied to various fields such as subsurface carbon dioxide storage, geological disposal of spent nuclear fuel, and geothermal development both domestically and internationally, and the modeling validity has been examined by comparing the results with experimental measurements and other numerical codes. In the present study, a benchmark test of the TOUGH-FLAC approach was performed based on a coupled thermal-hydro-mechanical behavior problem with an analytical solution. The analytical solution is related to the temperature, pore water pressure, and mechanical behavior of a fully saturated porous medium that is subjected to a point heat source. The robustness of the TOUGH-FLAC approach was evaluated by comparing the analytical solution with the results of numerical simulation. Additionally, the effects of thermal-hydro-mechanical coupling terms, fluid phase change, and timestep on the computation of coupled behavior were investigated.

• Journal of the Korean GEO-environmental Society
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• v.10 no.3
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• pp.13-20
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• 2009

Generally, soil is regarded as fully saturated in Geotechnical Engineering and under ground structure design. Because it is in convenience and safety. But soils treated in field are almost in unsaturated state. Design in unsaturated state is difficult comparing with saturated soil. In unsaturated soil mechanics, parameters are usually not constant unlike saturated soil mechanics. Additionally lab or field tests in unsaturated soil mechanics are required more cost, time and theoretical difficulty. One of essential requisites for examination about unsaturated soil is Soil-Water Characteristic Curve (SWCC). It show the relation between soil suction and soil water content. Through many studies in and out of country, computation and testing methods for SWCC were introduced. But in this the country, most soil is granite soil that is widely spread in Korea. And the studies for granite soil's SWCC are not enough yet. In this paper, through studying for existing proposal methods about computation SWCC and collection data for domestic granite soils, It was determined the suitable method for domestic granite soils, and computed each granite soil's SWCC. The purpose of this paper is establishing database for domestic granite soil's SWCC as each region to convenience for applying to actual affairs. For this, studying about existing proposal methods for SWCC was performed and a computer program Soil-Vision is used. Furthermore for verification theoretical and testing methods were also performed.

• Journal of the Korean GEO-environmental Society
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• v.11 no.10
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• pp.15-24
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• 2010

In the case of underground power utilities pipe such as circular pipe, the most difficult problem is low compaction efficiency of the bottom of pipe inducing the failure of utilities. To overcome this problem, various studies have been performed and one of these is CLSM(Controlled Low Strength Materials) accelerated flow ability. But underground power utilities pipe backfill materials is also needed to have good thermal property that can dissipate the heat as rapidly as it is generated. So, in this study, we performed thermal resistancy test for various materials such as sand, weathered soil, clay and mixed soil to analyze the thermal characteristics of CLSM(Controlled Low Strength Materials) with accelerated flow ability for various conditions(water content, unit weight, void ratio, curing time) and to evaluate the applicability for backfill material of underground power utilities pipe. The test results of 16 specimens for thermal resistancy test showed good thermal property that maintained below $85^{\circ}C\;cm/W$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.111-118
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• 2016

The scaling of concrete caused by the combined effects of frost and deicing salt is one of the principle causes of damage to transportation infrastructure in cold-climate regions. In this study, to evaluate the factors affecting scaling resistance of concrete, the relationship between the properties of concrete, such as the mechanical properties and pore structure, and scaling resistance was examined experimentally. The test results showed that the scaling resistance was strongly dependent on the absorption properties of concrete, but not on the compressive strength. Furthermore, it is believed that both the spacing factor and specific surface of the air voids was not a good parameter for evaluating the scaling resistance of concrete. SGC concrete was less durable than OPC and SFC concrete with respect to the scaling resistance in the scope of the present study.

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.3
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• pp.445-456
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• 1992

A two dimensional finite element model was constructed to analyze the mechanical behavior of a five unit fred partial denture(FPD) with a 2nd premolar pier abutement either employing a rigid or nonrigid connector. Gap elements were used to model the clearance space of the nonrigid connector. All FPDs with rigid or nonrigid connectors reduced the magnitude of stress in the periodontium as compared to the control, with both normal or reduced bone support. An FPD with rigid connectors induced the smallst stresses in the periodontium. A FPD with a nonrigid connector on the mesial of the molar abutment exhibited the most undesirable mechanical stress states and deformations.

• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.371-379
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• 2004

Soil investigation data at 7 different locations around Honam costal region were analyzed and experimental correlations between soil properties and parameters of soft clay were presented. Most soils were classified as CL and CH by the Unified Soil Classification System and were unstable structurally because the water contents were generally greater than the liquid limits. The compression index has good correlations with water content, liquid limit and initial void ratio. The trend of these correlations were similar to the Skempton equation Cc = 0.009(LL -10) and other studies for Korean soft clays but the constants were small different. The slope of these correlations for Honam costal region were slightly greater than those for Kyunggi costal region and Kyungnam costal region. The correlation coefficient (R) between the liquid limit and the plastic index is 0.93. It is seen that not only the water content and the liquid limit but also the water content and the initial void ratio are correlate, therefore the experimental equations were presented for the practical purpose.

• Journal of the Korean GEO-environmental Society
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• v.14 no.10
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• pp.39-47
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• 2013

Recently, there have been various domestic construction activities related to the reclamation of the dredged soils to expand the land use. However, the reclaimed grounds made of the dredged soils cause various problems due to highly compressible and low shear strength nature. Particularly, this nature induces huge problems in case of the harbor facilities and road construction on the reclaimed sites. Furthermore, in the reclamation activities, the marine dredged soils are often used instead of the well sorted sand, which induces problems of compressibilities. Therefore, in this study, the mechanical characteristics of artificial soil mixture of kaolinite representing the marine dredged soils and the pond ash. A large consolidometer is designed and manufactured to produce the artificial soil mixture. To represent various mixing ratio between the fly ash and bottom ash in the pond ash, six samples with the same stress history are made with different mixing ratio among kaolinite, bottom ash and fly ash. Isotropically consolidated and undrained compression tests are performed to investigate the shear characteristics of soil mixtures. Based on the experimental results, as the components of mixed ash increase, the friction angle increase and the cohesion values decrease. Also, the porepressure parameters at failure, Af increase with the mixing components of the pond ash. The portion of bottom ash has more impact on the shear behavior than that of fly ash.

• Journal of the Korean Geotechnical Society
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• v.25 no.10
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• pp.111-122
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• 2009

Dissolution of some of geo-materials may yield the loss of the soil strength and the settlement of earth structures. The goal of this study is to monitor the several physical behaviors of soluble mixtures during dissolution. Sand-salt mixtures are used to monitor the meso to macro response including the settlements and shear waves. The mixtures of photoelastic and ice disks are used to monitor micro to meso behavior of soluble mixture including the void ratio, force chain, coordination number and horizontal force changes. In the sand-salt mixtures, shear waves are measured by using bender elements in conventional oedometer cells. In the photoelastic disk - ice disk mixtures, micro to meso response are measured by digital images and load cells. The shear wave velocity decreases at the initial stage of the dissolution, and then increases and approaches to asymptotic value. The larger dissoluble particle and the more random packing produces the severe horizontal fore change. After dissolution, the void increases and the coordination number decreases. This study demonstrates that the particle level behavior such as the changes of the force chain, void ratio, and coordination number affects the global behavior such as the change of the shear wave velocity and horizontal force of the system.

• Journal of the Korean Geosynthetics Society
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• v.15 no.3
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• pp.1-12
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• 2016

In this study, the impact of sand and weathered granite soil is analyzed by changing the internal temperature from $20^{\circ}C{\sim}70^{\circ}C$C by installing a heating coil inside the triaxial cell. To check the effect on weathered granite soil due to increase of temperature and number of heating-coiling cycles are analyzed by measuring the temperature by using thermometer installed inside the triaxial cell and due to that deviator stress also occurred during the consolidated undrained test. To analyze the effect of weathered granite soil with change of temperature during undrained testing. The deviator stress and pore pressure is measured. As a result, pore pressure increases and the deviator stress decreases with rise of temperature.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1716-1720
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• 2006

침투는 지반이 충적토로 구성되어 있는 제방의 파괴를 야기하는 중요한 원인이다. 침투 해석 수치모형은 제방 침투와 관련된 문제 해석과 방지기법 설계에 있어 매우 유용한 방법이나, 각각의 수치모형은 적용상 한계와 문제점을 내포하고 있다. 실제 지하수 흐름은 간극률, 입자형상 및 크기, 포화도 등과 같은 토질특성, 내부침식과 같은 역학적 특성, 점성과 동결융해 같은 열역학적 특성, 그리고 화학적 특성 등 다양한 인자의 영향을 받는다. 이러한 물리적 인자 이외에도 침투 수치해석은 외력조건, 격자 크기(element size), 그리고 시간 간격(time step interval) 등 입력조건에 영향을 받기 때문에 이들 설정에 대한 검토를 시행하여야 한다. 본 연구에서는 침투 수치모형의 적절한 입력조건 범위를 검토하였으며, 격자크기는 계산시간과 해석결과 등 수치모의의 효율성을 고려하였을 때 홍수위 혹은 제방고의 1/10이하로 결정하면 타당할 것으로 판단된다. 그리고 침투수치모형의 시간 간격은 외력조건을 고려하여 1시간 이내로 설정하는 것이 바람직할 것으로 판단된다. 본 연구결과는 침투해석 수치모의의 유의사항을 검토하여 해석결과에 대한 불확실성과 위험요소를 제거하는데 도움이 될 것으로 판단된다.