• Korean Journal of Computational Design and Engineering
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• v.11 no.2
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• pp.138-147
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• 2006

A systematic approach to tetrahedral element or mesh generation, based on an advancing-front method and an optimal triangular mesh generation technique on the surface, is presented in this paper. The possible internal nodes are obtained by the octree-decomposition scheme. The initial tetrahedral mesh system is constructed by the advancing-front method and then it is improved by the quality improvement processes including mesh swapping and nodal smoothing. The approach is evaluated by investigating the normalized length, the normalized volume, the dihedral angle and the normalized quality

• Journal of computational fluids engineering
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• v.2 no.2
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• pp.26-34
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• 1997

An implicit viscous turbulent flow solver is developed for two-dimensional geon unstructured triangular meshes. The flux terms are discretized based on a cell-centered formulation with the Roe's flux-difference splitting. The solution is advanced in time us backward-Euler time-stepping scheme. At each time step, the linear system of equation approximately solved wi th the Gauss-Seidel relaxation scheme. The effect of turbulence is with a standard k-ε two-equation model which is solved separately from the mean flow equation the same backward-Euler time integration scheme. The triangular meshes are generated advancing-front/layer technique. Validations are made for flows over the NACA 0012 airfoil. Douglas 3-element airfoil. Good agreements are obtained between the numerical result experiment.

• Solar Energy
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• v.9 no.1
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• pp.43-52
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• 1989

Heat transfer rate and heat flux from the condenser with internally triangular fins rotating heat pipe has been numerically studied by finite element method. The results of numerical and P.J. Martos' experimental showed good agreement and it was able to predict to the performance of a rotating heat pipe. By increasing fin half angle or fin height, heat transfer rate from condenser was increased slightly but heat flux was decreased. By increasing condenser radius or r.p.m. of rotating heat pipe, heat transfer rate and heat flux was increased rapidly. Heat transfer rate was rapidly increased with increasing fin numbers in case of few fm numbers but slowly increased at many fin numbers. So the optimum fin numbers were a half of maximum fin numbers which was able to install in the condenser of a rotating heat pipe.

• 한국전산유체공학회:학술대회논문집
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• 1997.10a
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• pp.29-37
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• 1997

An implicit viscous turbulent flow solver is developed for two-dimensional geometries on unstructured triangular meshes. The flux terms are discretized based on a cell-centered finite-volume formulation with the Roe's flux-difference splitting. The solution is advanced in time using an implicit backward-Euler time-stepping scheme. At each time step, the linear system of equations is approximately solved with the Gauss-Seidel relaxation scheme. The effect of turbulence effects is approximated with a standard $k-{\varepsilon}$ two-equation model which is solved separately from the mean flow equations using the same backward-Euler time integration scheme. The triangular meshes are generated using an advancing-front/layer technique. Validations are made for flows over the NACA0012 airfoil and the Douglas 3-element airfoil. Good agreements are obtained between the numerical results and the experiment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.10
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• pp.788-794
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• 2014

In this paper, the transient response analysis of the trapezoidal corrugated plate subjected to the pulse load is investigated by the theoretical method. Three types of pulse loads are considered: stepped, isosceles triangular and right triangular pulse loads. The corrugated plates can be represented as an orthotropic plate. Both the effective extensional and flexural stiffness of this equivalent orthotropic plate are considered in the analysis. The plate is stiffened by concentric stiffeners perpendicular to the corrugation direction. The stiffening effect is represented by the discrete stiffener theory. This theoretical results are validated by those obtained from 3D finite element analysis based on shell elements. Some numerical results are presented to check the effect of the geometric properties.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.405-412
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• 1998

According to the relative stiffness between the half-space and plate or loading condition, some parts of the plate can be separated from the half-space. The finite element procedure to determine the contact area by considering the distribution of contact pressure between plate and the elastic half-space is developed. The vertical surface displacements of the elastic half-space can be obtained through the integrations of the Boussinesq's solution for a point load. The rectangular plate on the elastic half-space is modeled by the 8-node rectangular and 6-node triangular elements and the Mindlin plate theory is used in oder to consider the transverse shear effect. In this study, the contact area may be determined approximately by the analysis with rectangular elements. From this results, the mesh pattern is modified by using triangular and rectangular elements. The contact area can be determined by the new mesh pattern with a relatively sufficient accuracy.

• Journal of KSNVE
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• v.3 no.3
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• pp.259-269
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• 1993

For efficient use of composite materials in engineering applications the dynamic behavior, that is, natural frequencies, nodal patterns should be informed. This study presents the experimental and FEM results for the free vibration of cantilevered, symmetrically and antisymmetrically laminated composite triangular plates. The natural frequencies and nodal patterns of a number of CFRP, GFRP, composite-Aluminum and CFRP-GFRP hybrid composite plates are experimentally obtained. A method for the determination of the Young's modulus and test procedures are described. The natural frequencies are determined for a wide range of parameters: e.g., composite material constants, fiber angles and stacking sequences. Natural frequency and nondimensional frequency parameter results are compared with the finite element analysis and existing literatures. Agreement between experimental and calculated frequencies is excellent.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.11 no.3
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• pp.52-57
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• 1982

One-dimensional approximation for fin problems is widely used in current texts and industrial practice. The errors caused by this approximation is analysed for a longitudinal triangular fin by the numerical solution of two-dimensional fin equation. Two-dimensional solution is obtained by the finite element method and com pared with the one-dimensional esact solution. The results show that total heat transfer and fin efficiency are overestimated by the one-dimensional approximation. The factors which cause these errors are the Biot number (Bi) and the ratio of fin length to half the thickness (L/a). When Bi is smaller than 1.0 these errors are smaller than $10\%$, but when Bi is larger than 5.0 they are a few ten percents. Fin efficiency obtaned by one-dimensional and long fin assumption is valid only then Bi is small and L/a is large.

• Journal of the Korea Concrete Institute
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• v.28 no.6
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• pp.713-722
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• 2016

The goal of this study was to assess the seismic performance of hollow cast-in-place and precast reinforced concrete bridge columns with triangular reinforcement details. The developed material quantity reduction details are economically feasible and rational, and facilitate shorter construction periods. By using a sophisticated nonlinear finite element analysis program, the accuracy and objectivity of the assessment process can be enhanced. The used numerical method gives a realistic prediction of seismic performance throughout the input ground motions for several hollow column specimens investigated. As a result, triangular reinforcement details were designed to be superior to the existing reinforcement details in terms of required seismic performance.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.5
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• pp.904-913
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• 2002

In this paper, the dynamic stress intensity factors of fracture mechanics are numerically computed in time domain using the FEM. For which the finite element formulations are derived applying the Galerkin method to the equations of motion in convolution integral as has been presented in the previous paper. To assure the strain fields of r$^{-1}$ 2/ singularity near the crack tip, the triangular quarter-point singular elements are imbedded in the finite element mesh discretized by the isoparametric quadratic quadrilateral elements. Two-dimensional problems of the elastodynamic fracture mechanics under the impact load are solved and compared with the existing numerical and analytical solutions, being shown that numerical results of good accuracy are obtained by the presented method.