• 한국전산유체공학회:학술대회논문집
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• 2004.03a
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• pp.62-70
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• 2004

Interaction between fluid flow and thermal radiation has received considerable attention due to its numerous applications in engineering field. In this case the thermofluid properties of radiating fluid vary with the variation of temperature field caused by absorption and emission of radiant heat. To analyze the radiation heat transfer in radiating fluid, the simultaneous solution of the radiative transfer equation (RTE) and the fluid dynamics equations is required. This means that the numerical procedure used for the RTE must be computationally efficient to permit its inclusion in the other submodels, and must be compatible with the other transport equations. The finite volume method (FVM) and the discrete ordinates method (DOM) are usually employed to simulate radiation problems in generalized coordinates. These two representative methods are examined and compared, especially in view of the numerical integration of the radiation intensity over solid angle. The FVM shows better accuracy than the DOM owing to less constraints of the selection of control angle.

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.1
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• pp.105-111
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• 2002

When transporting multiple items by trucks of various size, one needs to assign a group of items to each truck so as to minimize the total cost, while meeting the weight and volume constraint of each truck. In this paper, we formulate the problem as an integer programming problem and propose four heuristic algorithms for the problem. Computer simulation is used to evaluate the average performance of the four heuristic algorithms for the consolidated transportation problem.

• Journal of Institute of Convergence Technology
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• v.4 no.2
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• pp.1-9
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• 2014

This paper examines feature-based reconstruction algorithm using feature-based modeling and based on topology optimization technology, which aims to achieve a minimal volume weight and to satisfy user-defined constraints such as stress, deformation related conditions. The finite element model after topology optimization allows us to remove some region of a solid model for predefined volume requirement. The stress or deformation distribution resulted from finite element analysis enables us to add some material to the solid model for a robust structure. For this purpose, we propose a feature-based redesign algorithm which inserts negative features to the solid model for material removal and positive features for material addition, and we introduce a bisection method which searches an optimal structure by iteratively applying the feature-based redesign algorithm. Several examples are considered to illustrate the proposed algorithms and to demonstrate the effectiveness of the present approach.

• ETRI Journal
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• v.28 no.6
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• pp.815-818
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• 2006

In the global Internet, a constraint-based routing algorithm performs the function of selecting a routing path while satisfying some given constraints rather than selecting the shortest path based on physical topology. It is necessary for constraint-based routing to disseminate and update link state information. The triggering policy of link state updates significantly affects the volume of update traffic and the quality of services (QoS). In this letter, we propose an adaptive triggering policy based on link-usage statistics in order to reduce the volume of link state update traffic without deterioration of QoS. Also, we evaluate the performance of the proposed policy via simulations.

• Steel and Composite Structures
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• v.48 no.5
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• pp.583-597
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• 2023

This paper introduces a novel approach to multi-material topology optimization (MTO) targeting in-plane bi-directional functionally graded (IBFG) non-uniform thickness Reissner-Mindlin plates, employing an alternative active phase approach. The mathematical formulation integrates a first shear deformation theory (FSDT) to address compliance minimization as the objective function. Through an alternating active-phase algorithm in conjunction with the block Gauss-Seidel method, the study transforms a multi-phase topology optimization challenge with multi-volume fraction constraints into multiple binary phase sub-problems, each with a single volume fraction constraint. The investigation focuses on IBFG materials that incorporate adequate local bulk and shear moduli to enhance the precision of material interactions. Furthermore, the well-established mixed interpolation of tensorial components 4-node elements (MITC4) is harnessed to tackle shear-locking issues inherent in thin plate models. The study meticulously presents detailed mathematical formulations for IBFG plates in the MTO framework, underscored by numerous numerical examples demonstrating the method's efficiency and reliability.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.4
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• pp.495-503
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• 2001

In a functionally graded materials(FGM), two constituent material particles are mixed up according to a specific volume fraction distribution so that its thermoelastic behavior is definitely characterized by such a material composition distribution. Therefore, the designer should determine the most suitable volume fraction distribution in order to design a FGM that optimally meets the desired performance against the given constraints. In this paper, we address a numerical optimization procedure, with employing interior penalty function method(IPFM) and FDM, for optimizing 2D volume fractions of heat-resisting FGMs composed of metal and ceramic. We discretize a FGM domain into finite number of homogenized rectangular cells of single design variable in order for the optimization efficiency. However, after the optimization process, we interpolate the discontinuous volume fraction with globally continuous bilinear function in order to enforce the continuity of volume fraction distributions.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.3
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• pp.223-233
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• 2012

This paper deals with free vibrations of the tapered Timoshenko beam with constant volume, in which both the rotatory inertia and shear deformation are included. The cross section of the tapered beam is chosen as the regular polygon cross section whose depth is varied with the parabolic function. The ordinary differential equations governing free vibrations of such beam are derived based on the Timoshenko beam theory by decomposing the displacements. Governing equations are solved for determining the natural frequencies corresponding with their mode shapes. In the numerical examples, three end constraints of the hinged-hinged, hinged-clamped and clamped-clamped ends are considered. The effects of various beam parameters on natural frequencies are extensively discussed. The mode shapes of both the deflections and stress resultants are presented, in which the composing rates due to bending rotation and shear deformation are determined.

• Journal of KSNVE
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• v.6 no.5
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• pp.587-594
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• 1996

The differential equation governing both the free vibrations and buckling loads of tapered beam-columns of regular polygon cross-section with constant volume were derived and solved numerically. The parabolic and sinusoidl tapers were chosen as the variable depth of cross-section for the tapered beam-column. In numerical examples, the clamped-clamped, hinged-clamped and hinged-hinged end constraints were considered. The variations of frequency parameters and first buckling load parameters with the non-dimensional system parameters are reported in figures, and typical vibrating mode shapes are presented. Also, the configurations of strongest columns were determined.

• Computational Structural Engineering
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• v.9 no.3
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• pp.135-143
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• 1996

The differential equations governing both the free vibrations and buckling loads of tapered beam-columns of circular cross-section with constant volume are derived and solved numerically. The effects of axial load are included in the differential equations. The parabolic equation is chosen as the variable radius of circular cross-section for the tapered beam-column. In numerical examples, the clamped-clamped, clamped-hinged and hinged-hinged end constraints are considered. The variations of the frequency parameters and buckling load parameters with the non-dimensional system parameters are presented in figures and the configurations of strongest columns are obtained.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2444-2447
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• 2008

A new 3D-PTV algorithm (a Volume PTV) based upon a hybrid fitness function has been constructed. A coherency fitness function is introduced using the information of space and time to sort out the correct particle pairs between the two camera images. The measurement system consists of two-high-definition-cameras($1k{\times}1k$), a Nd-Yag laser and a host computer. The developed algorithm has been employed to investigate the flow features of the cylinder wake. The Reynolds numbers with the cylinder diameter (d=10mm) are 360, 720, 900 and 1260. Two-dimensional displacements of the particles of each camera's image and neighbouring constraints were introduced to reduce the calculation loads. More than 10,000 instantaneous 3D vectors have been obtained by the constructed algorithm. The constructed algorithm could recover more than $80{\sim}90%$ of the particle numbers in the image.