• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.7
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• pp.869-874
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• 2007

In searching for solutions to multiobjective optimization problem, we find that there is no single optimal solution but rather a set of solutions known as 'Pareto optimal set'. To find approximation of ideal pareto optimal set, search capability of diverse individuals at population space can determine the performance of evolutionary algorithms. This paper propose the method to maintain population diversify and to find non-dominated alternatives in Game model based Co-Evolutionary Algorithm.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.03a
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• pp.43-46
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• 1998

This paper presents a new parameter tuning method for PID controller. The Ziegler-Nichols Parameter tuning has been widely known as a fairly heuristic method to good determine setting of PID controllers, for a wide range of common industrial processes It has a excessive overshoot in the set point response, set point weighting can reduced the overshoot to specified values. It will also be shown that set point weighting is superior to the conventional solution of reducing large overshoot by other method. In this paper, we will modified the Ziegler-Nichols tuning formula by fuzzy set. These method will give appreciable improvement in the performance of PID controllers.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2558-2561
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• 2008

In the present study, a parallel Taylor-Galerkin/level set based two-phase flow code was developed using finite element discretization and domain decomposition method based on MPI (Message Passing Interface). The proposed method can be utilized for the analysis of a large scale free surface problem in a complex geometry due to the feature of FEM and domain decomposition method. Four-step fractional step method was used for the solution of the incompressible Navier-Stokes equations and Taylor-Galerkin method was adopted for the discretization of hyperbolic type redistancing and advection equations. A Parallel ILU(0) type preconditioner was chosen to accelerate the convergence of a conjugate gradient type iterative solvers. From the present parallel numerical experiments, it has been shown that the proposed method is applicable to the simulation of large scale free surface flows.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.69-73
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• 2002

We have designed and fabricated a low-cost, V-band CPW receiver chip set using GaAs PHEMT technology for the application of millimeter-wave wireless communication systems. Low noise amplifiers and down-converters were developed for this chip set. The fabricated low noise amplifier showed an S$\sub$21/ gain of 14.9 ㏈ at 60 ㎓ and a noise figure of 4.1 ㏈ at 52 ㎓. The down-converter exhibited a high conversion gain of 2 ㏈ at the low LO Power of 0 ㏈m. This work demonstrates that the GaAs PHEMT technology is a viable low-cost solution for V-band applications.

• Journal of applied mathematics & informatics
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• v.29 no.5_6
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• pp.1179-1191
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• 2011

In this paper, we introduce a new iterative scheme for finding a common element of the set of fixed points of a finite family of strict pseudocontractions and the solution set of pseudomonotone and Lipschitz-type continuous equilibrium problems. The scheme is based on the idea of extragradient methods and fixed point iteration methods. We show that the iterative sequences generated by this algorithm converge strongly to the common element in a real Hilbert space.

• Journal of the military operations research society of Korea
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• v.30 no.1
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• pp.48-69
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• 2004

An optimal allocation model for SAM-X by using a set covering model is suggested. This allocation model considers to guarantee the maximum security of vital areas from the attack of enemy aircraft(s) and missiles. In order to formulate this model, we applied the concept of parallel structure reliability to set covering model. This model gives both direction of the primary target line and location of the facility. When applied this model to the real situation, the solution of this model can be used to the references of decision making for the optimal military facility allocation.

• Korean Journal of Mathematics
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• v.28 no.3
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• pp.539-554
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• 2020

A set {a₁, a₂, …, a_m} of m distinct positive integers is called a D(-1)-m-tuple if the product of any distinct two elements in the set decreased by one is a perfect square. In this paper, we find a solution of Pellian equations which is constructed by D(-1)-triples and using this result, we prove the extendibility of D(-1)-pair with some conditions.

• Korean Management Science Review
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• v.10 no.2
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• pp.1-9
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• 1993

This paper shows the application of fuzzy set and nonlinear membership function to linear programming problems in a fuzzy environment. In contrast to typical linear programming problems, the objectives and constraints of the problem in a fuzzy environment are defined imprecisely. This paper describes that fuzzy linear programming models can be formulated using the basic concepts of membership functions and fuzzy sets, and that they can be solved by quadratic programming methods. In a numerical example, a linear programming problem with two constraints and two decision variables is provided to illustrate the solution procedure.

• Communications of the Korean Mathematical Society
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• v.27 no.3
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• pp.505-512
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• 2012

In this paper, we introduce an iterative scheme for finding a common element of the set of fixed points of a nonexpansive mappings and nonspreading mappings and the set of solution of an equilibrium problem on the setting of real Hilbert spaces.

• Bulletin of the Korean Mathematical Society
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• v.51 no.3
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• pp.621-640
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• 2014

In this paper, we introduce a new approximating method for finding the common element of the set of fixed points of nonexpansive mappings and the set of solution of system variational inequalities for finite family of inverse strongly monotone mappings and strictly pseudo-contractive of Browder-Petryshyn type mappings. We show that the sequence converges strongly to a common element the above two sets under some parameter controling conditions. Our results improve and extend the results announced by many others.