• Structural Engineering and Mechanics
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• v.44 no.2
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• pp.139-161
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• 2012

In this paper, the static behavior of bi-directional functionally graded (FG) non-uniform thickness circular plate resting on quadratically gradient elastic foundations (Winkler-Pasternak type) subjected to axisymmetric transverse and in-plane shear loads is carried out by using state-space and differential quadrature methods. The governing state equations are derived based on 3D theory of elasticity, and assuming the material properties of the plate except the Poisson's ratio varies continuously throughout the thickness and radius directions in accordance with the exponential and power law distributions. The stresses and displacements distribution are obtained by solving state equations. The effects of foundation stiffnesses, material heterogeneity indices, geometric parameters and loads ratio on the deformation and stress distributions of the FG circular plate are investigated in numerical examples. The results are reported for the first time and the new results can be used as a benchmark solution for future researches.

• Structural Engineering and Mechanics
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• v.46 no.3
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• pp.403-416
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• 2013

This paper describes new optimization strategy that offers significant improvements in performance over existing methods for geometry design of frame structures. In this study, an imperialist competitive algorithm (ICA) and ant colony optimization (ACO) are combined to reach to an efficient algorithm, called Imperialist Competitive Ant Colony Optimization (ICACO). The ICACO applies the ICA for global optimization and the ACO for local search. The results of optimal geometry for three benchmark examples of frame structures, demonstrate the effectiveness and robustness of the new method presented in this work. The results indicate that the new technique has a powerful search strategies due to the modifications made in search module of ICACO. Higher rate of convergence is the superiority of the presented algorithm in comparison with the conventional mathematical methods and non hybrid heuristic methods such as ICA and particle swarm optimization (PSO).

• Structural Engineering and Mechanics
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• v.17 no.3_4
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• pp.557-572
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• 2004

Control systems are used to limit structural lateral deflections during large external loads such as winds and earthquakes. Most recently, the semi-active control approach has grown in popularity due to inexpensive control devices that consume little power. As a result, recently designed control systems have employed many semi-active control devices for the control of a structure. In the future, it is envisioned that structural control systems will be large-scale systems defined by high actuation and sensor densities. Decentralized control approaches have been used to control large-scale systems that are too complex for a traditional centralized approach, such as linear quadratic regulation (LQR). This paper describes the derivation of energy market-based control (EMBC), a decentralized approach that models the structural control system as a competitive marketplace. The interaction of free-market buyers and sellers result in an optimal allocation of limited control system resources such as control energy. The Kajima-Shizuoka Building and a 20-story benchmark structure are selected as illustrative examples to be used for comparison of the EMBC and centralized LQR approaches.

• Architectural research
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• v.16 no.2
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• pp.57-65
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• 2014

A study on the static analysis of Timoshenko beams is presented. A beam element is developed by using isogeometric approach based on Timoshenko beam theory which allows the transverse shear deformation. The identification of transverse shear locking is conducted by three refinement schemes such as h-, p- and k-refinement and compared to other reference solutions. From numerical examples, the present beam element does not produce any shear locking in very thin beam situations even with full Gauss integration rule. Finally, the benchmark tests described in this study is provided as future reference solutions for Timoshenko beam problems based on isogeometric approach.

• Bulletin of the Korean Mathematical Society
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• v.50 no.6
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• pp.2035-2051
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• 2013

In this paper, we study numerical schemes for solving multi-dimensional option pricing problem. We compare the direct solving method and the Operator Splitting Method(OSM) by using finite difference approximations. By varying parameters of the Black-Scholes equations for the maximum on the call option problem, we observed that there is no significant difference between the two methods on the convergence criterion except a huge difference in computation cost. Therefore, the two methods are compatible in practice and one can improve the time efficiency by combining the OSM with parallel computation technique. We show numerical examples including the Equity-Linked Security(ELS) pricing based on either two assets or three assets by using the OSM with the Monte-Carlo Simulation as the benchmark.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.10
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• pp.49-56
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• 1992

A new global routing algorithm which dynamically adjusts its cost parameters depending on the given routing poroblem to find a near optimum solution has been developed. The proposed algorithm efficiently performs global routing on general area in which all the pin positions are given. This algorithm is composed of two phases`In the first phase, it routes each net by searching a minimum cost path while ignoring the channel capacity. In the second iterative phase, it rips up nets which pass the channel at which the horizontal or vertical routing density exceeds the capacity and then it reroutes them using a modified set of cost parameters. Applying the above phases, paths for nets are found such that routing density doesn't exceed the capacity in each channel and that nets are routed with minimum cost. Experimental results for several benchmark examples including difficult-4, difficult-8, difficult-16, Primary1 and Primary2 show that our method generates better results than other published ones.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.165-173
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• 2007

In this paper, we propose a new minimum resources allocation algorithm for optimal design automation. In the proposed algorithm, the operation are allocated to functional units so that the number of interconnection wires between functional units can be minimized. The registers are allocated to the maximal clusters generated by the minimal cluster partitioning algorithm. Finally, the interconnection is minimized by removing the duplicated inputs of multiplexers and exchanging the inputs across multiplexers. The efficiency of the proposed allocation algorithm is shown by experiments using benchmark examples.

• Structural Engineering and Mechanics
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• v.59 no.6
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• pp.1071-1094
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• 2016

We employ the so-called problem-dependent linked interpolation concept to develop two cubic 4-node quadrilateral plate finite elements with 12 external degrees of freedom that pass the constant bending patch test for arbitrary node positions of which the second element has five additional internal degrees of freedom to get polynomial completeness of the cubic form. The new elements are compared to the existing linked-interpolation quadratic and nine-node cubic elements presented by the author earlier and to the other elements from literature that use the cubic linked interpolation by testing them on several benchmark examples.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.5
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• pp.1-17
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• 1997

With the increasing performance and density of VLSI scircuits as well as the popularity of portable devices such as personal digital assitance, power consumption has emerged as an important issue in the design of electronic systems. Low power design techniqeus have been pursued at all design levels. However, it is more effective to attempt to reduce power dissipation at higher levels of abstraction which allow wider view. In this paper, we propose a simultaneous scheduling and binding scheme which increases the correlation between cosecutive inputs to an operation so that the switched capacitance of execution units is reduced in datapath-dominated circuits. The proposed method is implemented and integrated into the scheduling and assignment part of HYPER synthesis environment. Compared with original HYPER synthesis system, average power saving of 23.0% in execution units and 14.2% in the whole circuits, ar eobtained for a set of benchmark examples.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.4
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• pp.85-92
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• 1995

A new partitioning algorithm has been developed to implement a large circuit by using multiple field programmable gate array (FPGA) chips. While the conventional partitioning is to minimze the number of nets cut under size constraints, partitioning for multiple FPGAs has several additional constraints so that each partitioned subcircuit can be implemented in a FPGA chip. To obtain satisfactory results under the constraints, the partitioning is performed in two steps whhich are the intial partitioning for global optimization and the iterative partitioning improvements for constraint satisfaction. Experismental results using the MCNC benchmark examples show that our partition method produces better results thatn those of other recent approaches on the average.