• Interaction and multiscale mechanics
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• 제4권4호
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• pp.321-336
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• 2011

This paper presents the results of static vertical load tests carried out on a model building frame supported by pile groups embedded in cohesionless soil (sand). The effect of soil interaction on displacements and rotation at the column base and also the shears and bending moments in the columns of the building frame were investigated. The experimental results have been compared with those obtained from the finite element analysis and conventional method of analysis. Soil nonlinearity in the lateral direction is characterized by the p-y curves and in the axial direction by nonlinear vertical springs along the length of the piles (${\tau}-z$ curves) at their tips (Q-z curves). The results reveal that the conventional method gives the shear force in the column by about 40-60%, the bending moment at the column top about 20-30% and at the column base about 75-100% more than those from the experimental results. The response of the frame from the experimental results is in good agreement with that obtained by the nonlinear finite element analysis.

• Wind and Structures
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• 제27권4호
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• pp.223-234
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• 2018

In this study, a simplified three-dimensional calculation model is developed for the dynamic analysis of soil-pile group-supertall building systems excited by wind loads using the substructure method. Wind loads acting on a 300-m building in different wind directions and terrain conditions are obtained from synchronous pressure measurements conducted in a wind tunnel. The effects of soil-structure interaction (SSI) on the first natural frequency, wind-induced static displacement, root mean square (RMS) of displacement, and RMS of acceleration at the top of supertall buildings are analyzed. The findings demonstrate that with decreasing soil shear wave velocity, the first natural frequency decreases and the static displacement, RMS of displacement and RMS of acceleration increase. In addition, as soil material damping decreases, the RMS of displacement and the RMS of acceleration increase.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권4호
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• pp.104-112
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• 2015

In this study, several factors which can have an effect on soil during strategic environmental assessment (SEA) are analyzed against a total of 86 administrative plans and development basic plans of the SEA. Other factors which could have influences on soil are also analyzed after examining contents and rules required for preparing the SEA statement. Then, we propose assessment factors on soils during the SEA procedure. We think that this study could give baseline data to set up assessment items, criteria, and techniques that are highly necessitated in preparation of the SEA statement in the near future.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.329-336
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• 2002

The earth structures and in-ground LNG tank, and buildings can be constructed with using artificial freezing method on the reclaimed land. In this study, upon freezing a saturated soil in a closed-system from the top, a considerable pressure was developed. The pressure is the result of the surface energy of a curved ice-water interface. The most significant of these parameters will have the greatest effect on the classification. In order to establish frost-susceptibility criteria based on frost heaving expansion pressure, more soils have to be tested. This study was initiated to investigate the soils frost heaving expansion pressure and moisture characteristics resulting from freezing and freezing-thawing cycle process. Weathered granite soils, sandy soil, sandy soil were used in the laboratory freezing test subjected to thermal gradients under closed- systems.

• 한국유기농업학회지
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• 제23권4호
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• pp.781-796
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• 2015

시설채소 무경운 유기재배와 분할관수 효과를 구명하고자 시험을 수행한 결과 1회 전량 관수한 경운재배 토양의 수분함량은 30 cm 깊이까지 관수개시 후 급격하게 증가 후 다음 관수 직전까지 계속하여 감소되었다. 경운 토양의 수분함량 편차는 토양이 깊어질수록 감소되었다. 1회 전량 관수한 무경운 토양 표토와 지하 20 cm 깊이의 수분함량은 해가 뜨기 시작하면 증가되고 야간에는 감소되는 증발산에 의한 주기적인 일변화를 보였다. 그리고 2회 분할 관수한 경운 표토와 무경운 표토와 지하 20 cm 깊이까지의 수분함량은 증발산에 의한 주기적인 일변화를 나타내었다. 토양의 염류농도는 관수 후 증가되기 시작하여 다음 관수 직전까지 계속하여 감소되었으며, 토양이 깊어질수록 염류농도 증가 시간은 지연되었다. 무경운 표토의 염류농도 오전 11시부터 정오 12시 사이에 증가되기 시작하여 오후 2~6시경을 정점으로 1일 1회 증가와 감소되는 증발산작용에 의한 일변화를 보였다. 30 cm 깊이의 무경운 토양에서는 염류농도의 일변화가 측정되지 않았다. 토양수분 함량과 염류농도는 경운방법에 관계없이 정(+)의 상관관계를 나타내었다. 무경운 토양에서 재배된 고추의 생육은 경운 토양에서 재배된 고추에 비하여 생육이 억제되는 경향을 보였다. 경운방법에 관계없이 50%씩 2회 분할 관수한 토양에서 재배된 고추는 1회 전량관수에 비하여 주지의 길이와 경경 등 생육이 증가되는 경향을 보였다. 고추의 수확과수는 1회 전량관수에 비하여 2회 분할 관수가 경운과 무경운 처리에서 각각 49%와 47% 정도 현저하게 증가되었다. 고추 수량은 무경운 재배가 관행 경운재배에 비하여 8% 정도 증수되었다. 2회 분할관수의 고추 수량이 1회 전량관수에 비하여 수확과수의 증가로 경운 재배에서는 36%, 무경운 재배에서는 39% 정도 현저하게 증수되었다.

• 상하수도학회지
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• 제28권5호
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• pp.581-587
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• 2014

Sediment basin that is typical facility installed for development business to prevent soil erosion has low removal efficiency and therefore, it causes complaints from the residents and has a bad effect on ecosystem. Thus there is a limit to control soil erosion using the existing design methods of sediment basin, so the purposes of this study is providing suitable design factors for sediment basin with regarding soil characteristic of development areas and analysing sedimentation characteristic by inflow concentration changes. The results, for analyzing the sedimentation characteristic by soil concentrations within approximately 2,000 ~ 20,000 mg/L of initial SS concentration, indicated similar sedimentation trends for same soil in the supernatant regardless of initial concentrations. However, for different soil characteristic (percent finer), there are different results in sedimentation rate and concentrations of the supernatant. Thus it is recommended that sediment basin to prevent soil erosion during construction should be designed based on retention time derived from soil sedimentation experiments regardless of inlet concentration. In addition, installing the soil erosion prevention facility at the back to satisfy effluent water quality should be considered to minimize soil erosion effectively.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2019년도 추계학술대회
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• pp.23-23
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• 2019

• 한국지반환경공학회 논문집
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• 제17권9호
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• pp.29-35
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• 2016

Being mostly made up of highly permeable basalt and volcanic ash soil, Jeju Island's lithosphere characterizes its streams to be dry, flowing only when precipitation is happening. Under this condition, this research was motivated to identify the need of conservation of underground water, which is taking up most of (84% of) Jeju's water usage, and made an attempt to reduce the permeability of stream beds so that it can replace underground water and be used instead. To this end, this study suggested a simple method to make dry streams to carry water all-year-round by reducing permeability of stream floor. The experiment of permeability was performed on the porous basalt and compared it with that of same basalt with volcanic ash soil and Jumunjin sand layer added on top. The results showed a dramatic decrease in permeability of water when both volcanic ash soil and Jumunjin sand is were layered on top of porous basalt. Despite being gained in a controlled environment with a simple test, this result may provide a realistic and effective method of preserving Jeju Island's underground water which ultimately is a method of resolving water related issues.

• Advances in Computational Design
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• 제3권2호
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• pp.201-212
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• 2018

Decrease in availability of suitable subbase and base course materials for highway construction leads to a search for economic method of converting locally available troublesome soil to suitable one for highway construction. Present study insights on evaluation of benefits of stabilization of subgrade soils in term of extension in service life (TBR) and layer thickness reduction (LTR). Laboratory investigation consisting of Atterberg limit, Compaction, California Bearing Ratio, unconfined compressive strength and triaxial shear strength tests were carried out on two types of soil for varying percentages of stabilizers. Vertical compressive strains at the top of unstabilized and stabilized subgrade soils were found out by elastoplastic finite element analysis using commercial software ANSYS. The values of vertical compressive strains at the top of unstabilized and stabilized subgrade, were further used to estimate layer thickness reduction or extension in service life of the pavement due to stabilization. Finite element modeling of the flexible pavement layered structure provides modern technology and sophisticated characterization of materials that can be accommodated in the analysis and enhances the reliability for the prediction of pavement response for improved design methodology. If the pavement section is kept same for unstabilized and stabilized subgrade soils, pavement resting on lime, fly ash and fiber stabilized subgrade soil B will have service life 2.84, 1.84 and 1.67 times than that of unstabilized pavement respectively. The flexible pavement resting on stabilized subgrade is beneficial in reducing the construction material. Actual savings would depend on the option exercised by the designer for reducing the thickness of an individual layer.

• Geomechanics and Engineering
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• 제24권1호
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• pp.67-79
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• 2021

The influence of ground motions on the seismic response of utility tunnels was investigated. A series of small-scale shaking table model tests were carried out under uniform excitation in the transverse direction. Different peak accelerations of EL-Centro and Taft earthquake waves were applied. The acceleration responses, earth pressure, seismic strain, bending moment and structure deformations were measured and discussed. The results showed that the types of earthquake waves had significant influences on the soil-structure acceleration responses. However, the amplitude of the soil acceleration along the depth showed consistent variation regardless of the types of earthquake waves and tunnels. The horizontal soil pressure near the top and bottom slabs showed obviously larger values than those at other depths. In general, the strain response in the outer surface was more significant than that on the inner surface, and the peak strain in the end section of the model was larger than that in the middle section. Moreover, the bending moment at the corner points was much larger than that at middle point, and the bending moment was greatly affected by both input accelerations and seismic wave types. The opposite direction of shear deformation on the top and bottom slabs presented a rotation trend of the model structure.