• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3A
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• pp.429-437
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• 2006

Existing basic mechanical models which are methods characterizing viscoelastic materials were first reviewed to account for viscoelastic behavior of the asphalt pavement structure in this paper. A viscoelastic mechanical model considering a single load of vehicles subsequently was suggested and an equation that indicates the time-dependant behavior of asphalt pavements was derived from the proposed model. Non-destructive tests using falling weight deflectometer(FWD) were performed for a test section to estimate the application of the model. Both deflections and strains procured by the equation were compared to testing results according to loading history. By observing field measurements and theoretical evaluations, if two results are compared by the features of deflection according to time history, it could be concluded that the proposed model is expected to be suitable for prediction of the behavior of asphalt pavements because there is hardly difference between field data and calculated data.

• Journal of Korean Association for Spatial Structures
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• v.7 no.6
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• pp.69-74
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• 2007

Recently, to improve performance and strength of circular steel columns, application of concrete-filled steel tube(CFT) type are gradually increased. To accurately predict the plastic design of concrete-filled steel tube columns, a plasticity model is required which can be describe large deformation behavior of concretes and steels. In this study, elastic-plastic large deformation analysis is developed by using the plasticity model of structural steels, and accurate and validity of the developed program is verified by comparing between the experiment and the analysis for concrete-filled steel tube column. In concrete-filled steel tube columns, influence of initial deflection on ultimate strength behavior is investigated by using developed program.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6A
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• pp.625-639
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• 2009

Experimental and analytical studies are performed on the mechanical behavior of concrete-filled tubular(CFT) truss girders for different f/L ratios. Bending tests are conducted on two CFT truss girder specimens to determine fundamental structural characteristics such as the strength and deformation properties. Nonlinear material models for CFT members subjected to an axial compressive force are compared in this paper by using the nonlinear finite element program, ABAQUS. Previous researchers have proposed several nonlinear stress-strain models of confined concrete. In this study, the nonlinear analyses are performed applying several stress-strain models for confined concrete proposed by Mander, Sakino, Han, Susantha and Ellobody, and the results are compared with the experimental results in terms of load-deflection and load-strain relationships. Based on the comparisons of the load-deflection relationships, the models proposed by Mander and Susantha provide a maximum load about 12.0~13.8% higher and that by Sakino gives a maximum load about 7.6% higher than the experimental results. The models proposed by Han and Ellobody give a maximum load only about 0.2~1.2% higher than the test results, showing the best agreement among the proposed stress-strain models. However, the load-strain relations predicted by the existing models generally provide conservative results exhibiting larger strains than the experimental data.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3D
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• pp.435-444
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• 2006

This paper investigates the effect of 3-dimensional FE models to evaluation results of jointed concrete pavements which is back-calculated by AREA method. Sensitivity of 3-dimensional FE models developed to simulate the behavior of real jointed concrete pavement are analyzed after compared with 2-dimensional FE models using ILLISLAB. In comparison with 2-dimensional models, influence of concrete contraction under loading plate and base layer on surface deflections is more than that of loading configuration. Deflections at 3-dimensional model between linear and nonlinear temperature distribution under same temperature difference are similar, but noticeable differences are investigated in low elastic modulus of foundations. Dynamic deflections under loading plate are larger than static deflections in high elastic modulus of foundation, but smaller in low elastic modulus. Lower dynamic modulus of subgrade reactions are backcalculated by dynamic deflections than by static deflections. But reverse trend is investigated in the backcalculated elastic modulus of concrete which describes trends of the field backcalculation values calculated from AREA method.

• Journal of the Korea Concrete Institute
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• v.13 no.5
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• pp.415-422
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• 2001

The present paper focuses on the development of a realistic analysis model for the deformation calculation of reinforced concrete beams subjected to fatigue loadings. The proposed model considers the effect of cyclic creep, which arises from the repeated loading, to calculate the deformation of reinforced concrete beams. A comprehensive experimental program has been set up to identify the deformation accumulation of reinforced concrete beams under repeated loadings. The major test variables were the concrete compressive strength and the magnitude of fatigue loads. The model was calibrated from the present test results. The proposed model allows more realistic analysis of reinforced concrete beams under fatigue loads, especially deformation accumulation of such beams.

• Proceedings of the Korean Fiber Society Conference
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• 1998.04a
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• pp.258-261
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• 1998

2차원 시스템과는 달리 3차원 의복 CAD 시스템을 이용하면, 직접 재단 봉제 과정을 거치지 않고도, 만들어진 의복의 형상과 착장 상태를 확인해볼 수 있다는 장점이 있다. 이러한 3차원 시스템에서는 의복의 자연스런 처짐, 이른바 드레이프(drape)를 잘 표현하여야만 실제에 최대한 가까운 의복의 형상을 보여줄 수 있다.(중략)

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.211-216
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• 2012

This paper presents methods to reduce the deflection of the battery-supporting structure on on-line electric vehicles (OLEVs). First, by testing various battery locations, a location is found that increases the dynamic stiffness of the OLEV. Second, static analysis is conducted to analyze the maximum deflection caused by the battery weight. In order to reduce the amount of deflection, the contributions of the battery-supporting structures are analyzed, and reinforcements are inserted. Then, another static analysis is conducted to compare the results of the base model and modified model. Consequently, through the static analysis, both the base model and modified model are similarly improved in terms of deflection, but the modified model is better than the base model at reducing the mass.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.422-424
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• 2012

본 연구에서는 수상위에 진수된 콘크리트 플로팅 폰툰에 상부골조를 단계별로 시공함에 따라 발생하는 추가 처짐이 상부골조에 미치는 영향을 고찰하고 하였다. 이러한 추가변형에 의한 상부골조에 추가 모멘트량을 산정하는 해석절차를 제시하였으며 제시된 절차에 따라 3층 예제 철골 건물을 해석하고 분석하였다. 제시된 시공단계를 고려한 해석 방법과 비교하여, 상부골조를 지반위에 고정하여 모델링하는 일반적인 해석은 수직하중에 의한 변형을 무시하여 설계하중을 과소평가 하며, 플로팅 구조물을 전체적으로 모델링하고 하부 폰툰에 등가의 스프링으로 치환하여 하중을 동시에 재하하는 모델은 과대한 처짐의 영향으로 설계하중을 과대 평가함을 알게 되었다.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.206-210
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• 2000

금형 및 자동차 산업에 널리 사용되는 앤드밀 가공에서 종종 소비자가 요구하는 가공 정밀도를 충족시켜 주지 못하는 경우가 발생한다. 이것은 열 변형, 공구 마모, 공작 기계 자체의 오차, 공구 처짐 등 다양한 원인이 존재한다. 본 연구에서는 공구 처짐으로 발생되는 가공 오차를 줄임으로써 가공 정밀도를 향상하기 위한 시스템을 개발하고자 한다. 이를 위해 3차원 볼 앤드밀의 절삭력 모델을 개발하고 시뮬레이션한다. 또한, 상용 CAD 시스템의 형상 및 가공 정보를 이용함으로써 모델링에서부터 가공 경로 생성, 그리고 경로 보정이라는 과정을 일괄적으로 수행할 수 있도록 한다. 이를 통해 사용자는 가공 전 시뮬레이션을 통해 가공 오차를 줄일 수 있는 기회를 제공 받는다. 따라서, 실제 가공에서 보다 높은 가공 정밀도를 얻을 수 있을 것이다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.1-13
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• 1993

In design of prestressed concrete structures, structural analysis is performed normally several times for selection of adequate sectional dimension and tendon amount. Especially for precast segmental multi-span bridges. time consuming structural analysis process due to time dependent material properties and structural system change could be effectively reduced by use of a reduced-span bridge model. 5-span and 3-span bridges are selected as reduced-span models for the 10-span full bridge to investigate the acceptability in practical design. The analytical results of deflection, total moment, statical moment, and ultimate moment of the reduced span-models are compared with those of the 10-span full bridge. Application of the load factors to structural analysis for ultimate moment calculation in prestressed concrete is reviewed and a rational method is proposed.