• Journal of the Society of Naval Architects of Korea
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• v.36 no.3
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• pp.50-59
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• 1999

This paper is concerned on the generation of an optimal section of wing in ground effect by a SQP method which is one of nonlinear optimization techniques. A potential panel method is used for the flow analysis and the ground effect is taken into account by an image method. The numerical method is first verified by an inverse problem where a shape of wing section is sought for the prescribed pressure distribution. The purpose of the present paper is to generate a wing section which can give a maximum lift subjected to the design constraints including the height stability which is important in the WIG design. The effect of the tail wing is also included.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.4
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• pp.117-128
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• 2016

Installation of earth grounding system is essential to ensure personnel safety and correct operation of electrical equipment. Earth parameters, especially, soil resistivity has to be determined in designing an efficient earth grounding system. The most common applied technique to measure soil resistance is Wenner four-point method. Implementation of this method is expensive, time consuming and cumbersome as large set of measurements with variable electrode spacing are required to obtain a one dimensional resistivity plot. It is advantageous to have a method which is of low cost and provides fast measurements. In this perspective, electrical resistance tomography (ERT) is applied to estimate subsurface resistivity profile. Electrical resistance tomograms characterize the soil resistivity distribution based on the measurements from electrodes placed in the region of interest. The nonlinear ill-posed inverse problem is solved using iterated Gauss-Newton method with Tikhonov regularization. Through extensive numerical simulations, it is found that ERT offers promising performance in estimating the three-dimensional soil resistivity distribution.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.2
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• pp.138-143
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• 2006

This paper presents intelligent digital redesign method for hybrid state space fuzzy-model-based controllers. For effectiveness and stabilization of continuous-time uncertain nonlinear systems under discrete-time controller, Takagi-Sugeno(TS) fuzzy model is used to represent the complex system. And global approach design problems viewed as a convex optimization problem that we minimize the error of the norm bounds between nonlinearly interpolated linear operators to be matched. Also, by using the bilinear and inverse bilinear approximation method, we analyzed nonlinear system's uncertain parts more precisely. When a sampling period is sufficiently small, the conversion of a continuous-time structured uncertain nonlinear system to an equivalent discrete-time system have proper reason. Sufficiently conditions for the global state-matching of the digitally controlled system are formulated in terms of linear matrix inequalities (LMIs). Finally, a TS fuzzy model for the chaotic Lorentz system is used as an . example to guarantee the stability and effectiveness of the proposed method.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.80-84
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• 2000

Network parameters in power systems are indispensable for all of power system engineering studies, including the power flow calculation and the state estimation. The network parameters required for the studios, in general, are estimated by using several estimation techniques, since it Is very difficult to measure. To improve the estimation accuracy of the network parameters, this paper adopt the synchronized phasor measurements which are acquired from the Phasor Measurement Unit with built-in GPS receiver. In this paper, the parameter estimation problem is formulated with over-determined nonlinear measurement equations and solved with Newton-Raphson method and pseudo-inverse. The effectiveness of the proposed parameter estimation with the synchronized phasor measurements is verified through some case studies with IEEE sample system. The results are very promising.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.8
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• pp.415-422
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• 2000

This paper presents a new algorithm for hierarchical optimal control of nonlinear systems. The proposed method is simple because the solutions are obtained by only exchanging informations of coefficient vector based on interaction prediction principle and FWT(fast Walsh transform) in upper and lower level. Since we solve two point boundary problem with Picard's iterative method and the backward integral operational matrix of Walsh function to obtain the optimal vector of each independent subsystem, the algorithm is simple and its operation is fast without inverse matrix and kronecker product operation. In simulation, the proposed algorithm's usefulness is proved by comparison with the global optimal control methods.

• International Journal of Control, Automation, and Systems
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• v.4 no.3
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• pp.318-324
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• 2006

The mobile manipulator is expected to work in partially defined or unstructured environments. In our global/local approach to path planning, joint trajectories are generated for a desired Cartesian space path, designed by the global path planner. For a local path planner, inverse kinematics for a redundant system is used. Joint displacement limit for the manipulator links is considered in the motion planner. In an event of failure to obtain feasible trajectories, the task cannot be accomplished. At the point of failure, a deviation in the Cartesian space path is obtained and a replanner gives a new path that would achieve the goal position. To calculate the deviation, a nonlinear optimization problem is formulated and solved by standard Sequential Quadratic Programming (SQP) method.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.28B no.9
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• pp.739-746
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• 1991

This paper develops a modified multilayer perceptron architecture which speeds up learning as well as the net's mapping accuracy. In Phase I, a cluster partitioning algorithm like the Kohonen's self-organizing feature map or the leader clustering algorithm is used as the front end that determines the cluster to which the input data belongs. In Phase II, this cluster selects a subset of the hidden layer nodes that combines the input and outputs nodes into a subnet of the full scale backpropagation network. The proposed net has been applied to two mapping problems, one rather smooth and the other highly nonlinear. Namely, the inverse kinematic problem for a 3-link robot manipulator and the 5-bit parity mapping have been chosen as examples. The results demonstrate the proposed net's superior accuracy and convergence properties over the original backpropagation network or its existing improvement techniques.

• Journal of Advanced Marine Engineering and Technology
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• v.15 no.3
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• pp.57-65
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• 1991

The quenching of steels by water is one of the important problems in engineering for the applications of heat treatment or continuous casting process, but the fundamental researches by the theoretical approaches have not been satisfactorily improved yet. The very rapid cooling problems by the thermal conduction including the latent heat of phase transformation in steel and the transient boiling heat transfer of water on the surface of the steel covering from $850^{\circ}C$ to $20^{\circ}C$ are the key problems of heat treatment. The present quenching experiments are performed for the cylindrical specimens of carbon steel, S45C of diameters (12-30). Nonlinear transient heat conduction and transient boiling heat transfer problem of water on the surface of specimens is analyzed by the numerical method of inverse heat conduction problem. The conditions for the calculation are that the initial temperature of specimens is $820^{\circ}C$ and the cooling water in bath are $20^{\circ}C$,$40^{\circ}C$,$60^{\circ}C$,$80^{\circ}C$,$95^{\circ}C$ with no agitation.

• Journal of applied mathematics & informatics
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• v.29 no.1_2
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• pp.227-245
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• 2011

In this paper, we introduce a new iterative method for finding a common element of the set of solutions for mixed equilibrium problem, the set of solutions of the variational inequality for a ${\beta}$inverse-strongly monotone mapping and the set of fixed points of a family of finitely nonexpansive mappings in a real Hilbert space by using the viscosity and Ces$\`{a}$ro mean approximation method. We prove that the sequence converges strongly to a common element of the above three sets under some mind conditions. Our results improve and extend the corresponding results of Kumam and Katchang [A viscosity of extragradient approximation method for finding equilibrium problems, variational inequalities and fixed point problems for nonexpansive mapping, Nonlinear Analysis: Hybrid Systems, 3(2009), 475-86], Peng and Yao [Strong convergence theorems of iterative scheme based on the extragradient method for mixed equilibrium problems and fixed point problems, Mathematical and Computer Modelling, 49(2009), 1816-828], Shimizu and Takahashi [Strong convergence to common fixed points of families of nonexpansive mappings, Journal of Mathematical Analysis and Applications, 211(1) (1997), 71-83] and some authors.

• Journal of IKEEE
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• v.20 no.3
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• pp.226-234
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• 2016

Electrical resistance tomography (ERT) is an imaging technique where the internal resistivity distribution inside an object is reconstructed. The ERT image reconstruction is a highly nonlinear ill-posed problem, so regularization methods are used to achieve desired image. The reconstruction outcome is dependent on the type of regularization method employed such as l2-norm, l1-norm, and total variation regularization method. That is, use of an appropriate regularization method considering the flow characteristics is necessary to attain good reconstruction performance. Therefore, in this paper, regularization methods are tested through numerical simulations with different flow conditions and the performance is compared.