• International Journal of Aeronautical and Space Sciences
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• 제11권4호
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• pp.319-325
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• 2010

For decades, researchers have rigorously studied the characteristics of flow traveling around blunt objects in order to gain greater understanding of the flow around aircraft, vehicles or vessels. Many different types of flow exist, such as boundary layer flow, flow separation, laminar and turbulent flow, vortex and vortex shedding; such types are especially observed around circular cylinders. Vortex shedding around a circular cylinder exhibits a two-dimensional flow structure possessing a Reynolds number within the range of 47 and 180. As the Reynolds number increases, the Karman vortex changes into a three-dimensional flow structure. In this paper, a numerical analysis was performed examining the flow and aero-acoustic field characteristics around a circular cylinder using an optimized high-order compact scheme, which is a high order scheme. The analysis was conducted with a Reynolds number ranging between 300 and 1,000, which belongs to B-mode flow around a circular cylinder. For a B-mode Reynolds number, a proper spanwise length is analyzed in order to obtain the characteristics of three-dimensional flow. The numerical results of the Strouhal number as well as the lift and drag coefficients according to Reynolds numbers are coincident with the other experimental results. Basic research has been conducted studying the effects an unstable three-dimensional wake flow on an aero-acoustic field.

• 전산구조공학
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• 제2권1호
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• pp.47-53
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• 1989

An efficient model for three-dimensional analysis of multistory structures with flexible floor diaphrgms is proposed in this paper. Three-dimensional analysis of a building structure using a finite element model requires tedious input data preparation, longer computation time, and larger computer memory. The model proposed in this study is developed by assembling a series of two-dimensional resisting systems and is considered to overcome the shortcomings of a three-dimensional finite element model without deteriorating the accuracy of analysis results. Static and dynamic analysis results obtained using the proposed model are in excellent agreement with those obtained using three-dimensional finite element models in terms of displacement, periods, and mode shapes. Effects of floor diaphragm flexibility on seismic response of multistory building structures are investigated.

• 한국해양공학회지
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• 제15권2호
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• pp.66-71
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• 2001

A sectional analysis of trunk-lid carried out by using the equilibrium approach based on the force balance together with geometric relations and plasticity theory. In computing a force balance equation, it is required to define a geometric curve approximating the shape of sheet metal at any step of deformation from the interaction between the die and the deformed sheet. The trunk-lid panel material is assumed to possess normal anisotropy and to obey Hill's new yield criterion. Deformation of each section of trunk-lid panel is simulated and composed to get the three-dimensional shape by using CAD technique. It was shown that the three-dimensional shape composition of the two-dimensional analysis.

• 한국군사과학기술학회지
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• 제22권4호
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• pp.460-466
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• 2019

It takes a lot of time and human resources to build a detailed three-dimensional finite element analysis model that is almost similar to the actual structure for sophisticated analysis, and a lot of experience and know-how is required to form a reliable analytical model. In this paper, the one-dimensional beam model connected by stiffness matrix through blade analysis library was compared with the results of three-dimensional analysis with the stress calculated through the process of dimensional restoration analysis based on the principle of virtual work. By comparing the stress calculated through dimensional restoration analysis with the three-dimensional analytical model, We will introduce the development status and application case of the blade analysis library by comparing efficiency and accuracy.

• 한국기계가공학회지
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• 제16권6호
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• pp.139-145
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• 2017

It is necessary to analyze the exact contact position and contact stress of the wheel-rail in order to predict damage to the wheel and rail. This study presents a wheel-rail contact analysis model that considers the deformation of the axle. When a wheel-rail contact analysis is performed using a full three-dimensional model of the wheelset and rail, the analytical model becomes very inefficient due to the increase in analysis time and cost. Therefore, modeling the element-coupling model of the wheel and rail as a three-dimensional element and the axle as a one-dimensional element is proposed. The wheel-rail contact characteristics in the proposed analysis model for straight and curved lines were analyzed and compared with the conventional three-dimensional analysis model. Considering the accuracy of the analysis results and time, the result shows that the proposed analytical model has almost the same accuracy as a full three-dimensional model, but the computational effort is significantly reduced.

• 한국구조물진단유지관리공학회 논문집
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• 제9권4호
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• pp.149-158
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• 2005

본 논문에서는 전통 목조 건축물의 보다 실제에 가까운 구조특성을 파악하고 건물에 대한 안전성을 평가하기 위하여 현존하는 대표적인 전통 목조 건축물인 부석사 무량수전을 대상으로 하여 최대한 실제와 유사한 거동상태가 되도록 건축물을 3차원 및 2차원으로 모델링하여 범용 구조해석 프로그램을 통한 구조해석을 실시한 후에 해석결과를 비교, 분석하고 검토하였다.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제21권3호
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• pp.125-142
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• 2017

In this paper, development of the three-dimensional structural analysis is performed by applying FETI-local method. In the FETI-local method, the penalty term is added as a preconditioner. The OPT-DKT shell element is used in the present structural analysis. Newmark-${\beta}$ method is employed to conduct the dynamic analysis. The three-dimensional FETI-local static structural analysis is conducted. The contour and the displacement of the results are compared following the different number of sub-domains. The computational time and memory usage are compared with respect to the number of CPUs used. The three-dimensional dynamic structural analysis is conducted while applying FETI-local method. The present results show appropriate scalability in terms of the computational time and memory usage. It is expected to improve the computational efficiency by combining the advantages of the original FETI method, i.e., FETI-mixed using the mixed local-global Lagrange multiplier.

• Korea-Australia Rheology Journal
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• 제13권2호
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• pp.97-106
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• 2001

Three-dimensional flow analysis was performed by using the control volume finite-element method for design of a profile extrusion die. Because polymer melt behavior is complicated and cross-sectional shape of the profile extrusion die is changing continuously, the fluid flow within the die must be analyzed three-dimensionally. A commercially available polypropylene is used for theoretical and experimental investigations. Material properties are assumed to be constant except for the viscosity. The 5-constant modified Cross model is used for the numerical analysis. A test problem is examined in order to verify the accuracy of the numerical method. Simulations are performed for conditions of three different screw speeds and three different die temperatures. Predicted pressure distribution is compared with the experimental measurements and the results of the previous two-dimensional study. The computational results obtained by using three dimensional CVFEM agree with the experimental measurements and are more accurate than those obtained by using the two-dimensional cross-sectional method. The velocity profiles and the temperature distributions within several cross-sections of the die are given as contour plots.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.169-173
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• 1998

Three dimensional database of building use in Central Obihiro City was created and displayed using three dimensional graphics and quicktime movies. Then intra structure of Central Obihiro City was analyzed based on this database using GIS and the results were also displayed using three dimensional graphics and quicklime movies.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.470-473
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• 2009

In this paper, back pressure forging processes of which back pressures are exerted by mechanical forces including spring reaction are simulated by three-dimensional finite element method. The basic three-dimensional approach extended from two-dimensional approach is accounted for. An axisymmetric backward and forward extrusion process having a back pressing die, which is exposed to oscillation of forming load due to variation of reduction ratios with stroke and its related frequent variation of major deforming region, is simulated by both two and three dimensional approaches to justify the presented approach by their comparison. A three-dimensional forging process having a back pressing die attached to the punch by a mechanical spring is simulated and the results are investigated to reveal accuracy of the presented approach.