• Journal of Aerospace System Engineering
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• v.17 no.6
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• pp.149-153
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• 2023

In this study, structural design and analysis of a duct stand for blowers were performed. This structure was an axial fan and blower for wind tunnel of the vehicle environmental test chamber. The design of the blower duct stand support structure was performed by investigation on various loads. Additionally, self-weight of the motor and weight of the duct were investigated and applied. The duct stand structure was designed by analyzing the load. The safety of the structural design results was evaluated through finite element analysis. Finally, the safety of the design result was verified.

• Journal of the Korean Geotechnical Society
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• v.39 no.3
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• pp.5-16
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• 2023

The effect of raft flexibility on piled raft foundations in sandy soil was investigated using a numerical analysis and an analytical study. The investigation's emphasis was the load sharing between piles and raft following the raft rigidity (K_R), end-bearing conditions. The case of individual piles and subsequently the response of groups of piles was analyzed using a 3D FEM. This study shows that the α_pr, load-sharing ratio of piled raft foundations, decreases as the vertical loading increases and as the K_R decreases. This tendency is more obvious when using friction piles compared to using end-bearing piles. The effect of raft rigidity is found to be more significant for the axial force distribution - each pile within the foundations has almost similar axial forces of the pile head with a flexible raft; however, each pile has different values with rigid rafts, especially with the end-bearing piles. The axial force of the pile base with floating piles shows similar point-bearing resistance for all the piles; however, it shows different values with end-bearing piles. The differential settlement ratio of rafts showed a larger value with lower K_R.

• Journal of the Korean Geotechnical Society
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• v.38 no.3
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• pp.5-16
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• 2022

Ground in extremely cold and hot regions can sink by various environmental factors. Ground settlement can generate the negative skin friction to pile shaft, increase the base load of pile, and cut the stability of the pile. This study proposed a member responding ground deformation which can be inserted inside the pile. The member slightly compresses according to the ground settlement to reduce the negative skin friction. As the member materials, this study considered spring and spring-dashpot. To assess the ability of the member, the present research performed model tests for piles with or without the member within settled ground. In the model tests, the base load, total shaft resistance, and horizontal earth pressure were monitored and analyzed. Experimental results show that the pile with spring member can reduce the negative skin friction under small settlement conditions whereas it acts similar to the pile without the member under large settlement conditions as the spring was no longer compressed. However, the pile with the spring-dashpot member can reduce the negative skin friction continuously upon the ground settlement as the dashpot delays the load transfer to the spring and locates friction force on the unloading path.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1A
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• pp.1-13
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• 2010

This paper presents an investigation on the geometric nonlinear behavior of cable-stayed bridges using geometric nonlinear finite element analysis method. The girder and mast in cable-stayed bridges show the combined axial load and bending moment interaction due to horizontal and vertical forces of inclined cable. So these members are considered as beam-column member. In this study, the nonlinear finite element analysis method is used to resolve the geometric nonlinear behavior of cable-stayed bridges in consideration of beam-column effect, large displacement effect (known as P-${\delta}$ effect) and cable sag effect. To analyze a cable-stayed bridge model, nonlinear 6-degree of freedom frame element and nonlinear 3-degree of freedom equivalent truss element is used. To resolve the geometric nonlinear behavior for various live load cases, the initial shape analysis is performed for considering dead load before live load analysis. Then the geometric nonlinear analysis for each live load case is performed. The deformed shapes of each model, load-displacement curves of each point and load-tensile force curves for each cable are presented for quantitative study of geometric nonlinear behavior of cable-stayed bridges.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.577-583
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• 2012

Structures floating in the ocean experience various kinds of external loads, among which wave load is considered as determining factor in structural design. Its relative size compared with wavelength may be used to classify whether the structure is relatively small or large. Traditionally, the small structures are assumed to have little diffraction and the wave loads on large structure are usually calculated by only considering inertia force according to diffraction. In this paper, rectangular floating structures usually used in the ocean, river, and lake are used to find the relationship between hydrodynamic forces and its structural response.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.81-81
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• 2011

현재 국내에서 사용하고 있는 교량구조물의 성능평가방법으로는 크게 공용하중에 대한 내하율을 구하기 위하여 허용응력개념이나 강도설계 개념을 적용한 내하력 평가 기법이 사용되고 있다. 그러나 위의 방법들은 일반적으로 공용연수의 경과에 따른 재료 및 구조적 성능의 손실과 여러 가지 하중 및 환경적 요인들의 불확실성으로 인하여 발생하는 손상 및 열화를 반영하기 어렵다. 그리고 제원 및 재료물성치의 불확실성에 대한 기존 설계 자료의 DB 부족으로 기존의 평가방법에서는 이러한 시간의 경과에 따른 성능저하를 정확히 산정할 수 없어 이론상의 값과 실제 구조물과의 차이로 인한 불확실성이 존재 한다. 이에 본 연구에서는 공용년수 경과에 따른 시설물의 재료 구조적인 성능 및 거동분석 수행, 신뢰성 해석 수행을 바탕으로 교량 안전성 평가의 합리성 및 현실성을 제고하며, 구조 신뢰성 해석을 수행함으로써 실제 구조물의 강도 한계상태에 대한 파괴확률을 산정하고 그에 대응하는 위험도를 평가함으로써 안전성 검토를 수행하였다. 본 실험을 통해 1. 재료 강도, 부재 제원, 긴장력, 작용하중 등에 있어 설계 시 가정과 실제 사용 환경 사이의 변동성이 존재한다는 것을 알 수 있었으며, 2. 연구 수행 결과 일반 정밀진단 및 해석에서는 얻을 수 없는 다양하고 중요한 결과를 산출할 수 있었으며 이러한 연구 결과를 바탕으로 개선된 성능평가 기법이 제안 될 수 있음을 알 수 있었다.

• Journal of the Korean GEO-environmental Society
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• v.9 no.7
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• pp.61-71
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• 2008

This study investigates the lateral resistance of micro-pile system when surcharge load is acting on the back of retaining wall. Both laboratory experiments and numerical analysis were performed. The experimental retaining wall model was developed on the laboratory-sized foundation. While surcharge load was acting, the interval and length varied as experimental variables. From the investigation it is known that the micro-pile system can effectively control the lateral displacement which is developed on the precast retaining wall. The effectiveness became increased as the pile interval reduced and the length of pile increased. The greatest reinforcing efficiency was shown when the pile length was 0.5H and the interval was 7D.

• Journal of the Korean GEO-environmental Society
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• v.22 no.10
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• pp.31-36
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• 2021

Estimation of accumulated rotational angles and settlements are critical in design of wind turbine foundation. However, there have been few exploring the response of bucket foundation to long-term cyclic loading. We performed a series of three-dimensional finite element analyses of bucket foundations installed in sands. An empirical formulation which captures the stiffness degradation observed in cyclic triaxial tests implemented into the finite element analysis in the form of a user subroutine. Using the stiffness degradation model the accumulated rotation and displacement of bucket foundation were calculated. Additionally, important factors affecting the response under cyclic loading were assessed.

• Journal of the Korean GEO-environmental Society
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• v.12 no.8
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• pp.59-67
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• 2011

The interaction of the ground deformation and composite piles, which is made of fiber glass, was analyzed for the effective pile application under vertical loads. This study was performed to conduct experimentation test and propose the material characteristics of the new type concrete injection circular FRP pile for the improvement of the defect of CFFT-Concrete composition piles and FRP-Concrete composition piles(FRP reinforced column direction). Additionally, in order to analyze the behaviour characteristics of composite pile and steel pile the numerical analyses were carried out.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.1
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• pp.25-31
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• 2024

This paper introduces a numerical analysis model capable of evaluating CFT (Concrete-Filled Tube) columns across all time stages, incorporating creep behavior analysis and inelastic analysis to account for time-dependent behavior. The proposed model is compared with experimental results, revealing that the numerical model presented in this paper demonstrates more accurate trends than existing design criteria. Following verification, a numerical analysis is conducted for each slenderness ratio, determining the ultimate load capacity and examining the short-term and long-term sustained load behavior of the overall CFT column members.