• Journal of Korean Society of Steel Construction
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• v.10 no.2 s.35
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• pp.177-186
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• 1998

The concrete filled steel tubular column have to superior in compressive load carrying capacity, compared with same section typed hollow steel tube column, and have many excellent structural properties, such as stiffness improvement by filled concrete, improvement of ductility by reinforced effect of local buckling, and the like. However, it has not clear the effect of interaction between steel tube and filled concrete, stress portion ratio and fracture mechanism of concrete. This study investigated to structural properties for high strength concrete filled steel tube column by loading conditions through a series of experiments. Especially, this study investigated the properties of structural behaviors for concrete filled steel tube column stress ratio by loading conditions and failure mechanism of filled concrete.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.2
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• pp.181-185
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• 1993

The effects of concentrations (6~9%), heating temperatures (80, 85, 90 and 95$^{\circ}C$) and heating methods (continuous, method A and instantaneous, method B) on the flow properties of cowpea flour (air-dried sediment) at 6$0^{\circ}C$ were studied. The gelatinized cowpea flour dispersions by method B had higher values of yield stress and consistency index but lower value of flow behavior index compared to those values of method A. The log values of consistency index were positively correlated with the concentration and heating temperature for both methods. The rate of increase in the consistency index value by method B at the same concentration was greater in all heating temperatures than that by method A.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.9
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• pp.1555-1561
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• 2003

Finite element analysis using modern constitutive equation is one of the most general tools to simulate the deformation behavior and to predict the life of the structure. Constitutive equation becomes complicated so as to predict the material behavior more accurately than the classical models. Because of the complexity of constitutive model, numerical treatment becomes so difficult that the calculation should be verified carefully. One-element tests, simple tension or simple shear, are usually used to verify the accuracy of finite element analysis using complicated constitutive model. Since this test is mainly focused on the time integration scheme, it is also necessary to verify the equilibrium iteration using material stiffness matrix and to compare FE results with solution of structures. In this investigation, viscoplastic solution of thick walled cylinder was derived considering axial constraints and was compared with the finite element analysis. All the numerical solutions showed a good coincidence with FE results. This numerical solution can be used as a verification tool for newly developed FE code with complicated constitutive model.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.191-196
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• 2015

해상 pedestal 크레인은 각종 운송물을 선박에 싣거나 내리는 해상 운송에 필수적인 장비이다. 따라서 구조적 안전성을 가지는 크레인 설계가 요구된다. 그의 일환으로 수행된 '해상 pedestal 크레인의 설계 개선을 위한 연구'에서는 기존 크레인의 기초 설계에 대해서 구조적 안전성올 평가하여 개선 방안을 제시하였다. 또한 좌굴 안정성 향상을 위한 보강재 설계를 수행하였다. 하지만 상세설계 관점에서 미비한 점이 있어 이를 보완할 필요성이 있다. 안전성 평가를 위해 필요한 응력을 계산하기 위해 EDISON-CSD프로그램을 통해 유한요소모델 해석을 활용한 구조해석을 수행하였다. 효율적인 해석을 위해 상세설계에 필요한 부분영역을 선택하여 모델링 하였으며 전체영역에서의 해석 결과 값을 등가 힘, 등가 모멘트로 환산하여 경계조건으로 부여하였다. 보강재간의 교차점 형상이 안전성에 미치는 영향을 보기위해 stiffener와 diaphragm의 교차점 형상(반원, 정사각형, 사다리꼴)에 따라 안전성 평가를 수행하였고, 안전 여유의 유효한 차이를 보이지 않음을 확인하였다. 평가에 필요한 응력계산을 위해 또한 Diaphragm의 좌굴에 대한 영향을 고려하기 위해 설계 규격 DNV-RP-201 8장(Buckling of girders)을 분석하였고, 안전성 평가에 반영하였다. 또한 실제 현장에서 보편적으로 사용되는 angle 형상 stiffener의 치수 도출을 위해 최적설계를 수행하였고, 모든 설계 제한조건을 만족하면서 최소의 무게를 가지는 합리적인 치수를 도출하였다.

• Journal of the korean Society of Automotive Engineers
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• v.11 no.2
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• pp.13-17
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• 1989

전기저항을 이용하여 두께가 1-7mm(0.03-0.27in)의 얇은 구조물을 국부적으로 융착시켜 접합하는 점용접은 자동차 및 항공기 부품산업에 활용도가 높아지고 있다. 구조물 접합시 점 용접은 너깃 주위의 열영향부에 잔류응력이 발생하므로 정적강도와 피로강도를 저하시키려는 원인이 되고 있다. 따라서 강도의 저하를 방지하기 위하여 용접시간, 용접전류량, 용접 가압력 등에 대한 최적 용접조건을 설정하기 위한 연구가 많이 진행중에 있다.

• Computational Structural Engineering
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• v.10 no.4
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• pp.165-175
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• 1997

In this paper, the stress, buckling and vibration analyses have been performed for several case with the spot weld stiffened rear side frame, the unstiffened rear side frame and the dual thickness laser weld rear side frame. For stress and vibration analyses, the clamped boundary condition with spring supports are used. But for the buckling analyses, the both ends simply supported boundary conditions are used. For the nummerical analyses, ANSYS 5.0 code is adopted. Maximum stress of the spot weld stiffened rear side frame occurs in the main frame and is 80.9 MPa. Maximum strain is 501 .mu.. The maximum stress of the dual thickness laser weld rear side frame of 1.8mm thickness structure is equal with the stress of spot weld stiffened frame. The weight of dual thickness laser weld frame can be reduced about 17.2%. For the stiffened spot weld rear side frame with both ends simply supported boundary conditon, the bucking load is 52.54 kN. When the thickness of the dual thickness laser weld rear side frame become 1.9mm thickness structure, the buckling load of the stiffenerd rear side frame is equal to that of dual thickness laser weld frame. The reduction of the structure weight is about 5%. The fundamental natural frequency of the stiffened spot weld rear side frame for bending mode is 163.6 Hz and that of the dual thickness laser weld rear side frame is 179.8 Hz.

• Geotechnical Engineering
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• v.8 no.2
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• pp.71-80
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• 1992

A new constitutive model is proposed for normally consolidated clays. A main skeleton of the proposed model is based on the concepts of the incremental stress-strain theory by Roscoe and Poorooshasb. The equation of the undrained stress path is formulated by introducing the new pore pressure parameter(C), which is the slope of the linear line in the plot of the normalized pore pressure against the stress ratio. Once the stress increment along the constant stress ratio path (followed by untrained stress path) is know, the volumetric strains are calculated from the linear characteristics between void ratio and logarithm of the mean normal stress for any stress ratio. Then the incremental shear strains are successfully predicted by applying the flow rule derived in the modified theory by Roscoe and Burland.

• Geotechnical Engineering
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• v.6 no.4
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• pp.19-32
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• 1990

Generally foundation is composed of complicated multi - layers. Primary objective of this study is to perform numerical analysis on the distribution of stresses on the subgrade with the variation of constitutive equations, the structures and the depth of layer, rigidity, loading condition, etc. Multi - layered soils has been treated as Burmister's elastic model. However, in this research it was intended to analyzed the distribution of stresses on the subgrade with all of the multi - layered soils by using the EVP(elasto - viscoplastic) model, one of the numerical program based on the Biot's equation as governing equation. The numerical results are compared with those by the Burmister's and the Fox'method, which in turn proves to be satisfactory. This research is aiming at investigating the mechanism of stress transfer within a foundation by using computer program for multilayers foundation.

• Computational Structural Engineering
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• v.10 no.3
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• pp.185-193
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• 1997

The order of the stress singularity that occurs at the termination of an interface between materials exhibiting bilinear stress-strain response under plane strain conditions has been calculated, The governing equation of elasticity together with traction-free boundary condition and interface continuity condition defines a two-point boundary value problem. The stress components near the free edge are assumed to be proportional to r/sup s-1/, with solutions existing only for certain values of s. Finding these values entails the solution of an eigenvalue problem. Because it has been impossible to integrate the differential equations analytically, the integration has been performed numerically with a shooting method coupled with a Newton improvement scheme.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.1
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• pp.90-99
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• 2002

The prediction of stress intensity factor(SIF) is one of the most important factors to analyse the propagation behavior of cracks in hull structural members. Up to now, however, simplified prediction method of SIF has not yet been established for the cracks experienced in large complex structures. As a first step to predict crack propagation behavior in a ship structure with very large structural redundancies, simplified SIF prediction formulas for various crack shapes were derived based on the results of the stress analysis under a non-crack condition in this study. The adequacy of the proposed method was then verified in comparison with other experimental and analysis results.