• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.389-392
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• 2008

This paper predicts the changes of natural frequencies due to the changes of mass at different point mass stations by using iterative calculation Transfer Matrices Method for different boundary conditions of a single beam structure (fixed-free and fixed-fixed beam). Firstly, the first three natural frequencies of an original beam are obtained using Transfer Matrices Method to verify the accuracy of the obtained results. The results are then compared with the exact solutions before purposely changing the parameter of mass. Both beams are modeled as discrete continuous systems with six-lumped-mass system. A single beam is broken down into a point mass and a massless beam which represent a single station and expressed in matrix form. The assembled matrices are used to determine the value of natural frequencies using numerical interpolation method corresponding to their mode number by manipulating some elements in the assembled matrix.

• Journal of applied mathematics & informatics
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• v.8 no.2
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• pp.305-326
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• 2001

We introduce a class of multilevel recursive incomplete LU preconditioning techniques (RILUM) for solving general sparse matrices. This techniques is based on a recursive two by two block incomplete LU factorization on the coefficient martix. The coarse level system is constructed as an (approximate) Schur complement. A dynamic preconditioner is obtained by solving the Schur complement matrix approximately. The novelty of the proposed techniques is to solve the Schur complement matrix by a preconditioned Krylov subspace method. Such a reduction process is repeated to yield a multilevel recursive preconditioner.

• Proceedings of the KIEE Conference
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• 2005.10a
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• pp.173-175
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• 2005

Two-dimensional orthogonal variable spreading codes are presented for multiplexing of forward link in direct sequence code division multiple access (DS-CDMA) multiple antennas system And the results of code generation and simulation of 2 dimensional orthogonal variable spreading factors on Jacket matrices are also be investigated. The bit error rate(BER) performance under a multi-user environment for the additive white Gaussian noise (AWGN) channel demonstrated that the proposed scheme could provide flexible rates and lower correlation values

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1384-1387
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• 2001

Presented is a method to predict strain responses from displacement measurements on a mechanical structure. The method consists of forming a transformation matrix, which is calculated from displacement and strain modal matrices. The modal matrices can be obtained by either finite element analysis or modal testing. One disadvantage of the method is that it requires displacements on all measuring points be measured simultaneously. The strain prediction method is applied to a simple simulated system.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1593-1598
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• 2004

In this paper, we use the input and output maps and develop simple procedures to obtain realizations for linear continuous-time systems. The procedures developed are numerically efficient and yield explicit formulae for the state space matrices of the realization in terms of the system parameters, notably the system modes. Both cases of the systems with distinct modes and repeated modes are treated. We also present a procedure for converting a realization obtained through the input or output map into the Jordan canonical form. The transformation matrices required to bring the realization into the Jordan canonical form are specified entirely in terms of the system modes.

• Proceedings of the KIEE Conference
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• 1997.07b
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• pp.446-448
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• 1997

The aim of this paper is to introduce a method designing the optimal model following boiler-turbine control system using genetic algorithms. This boiler-turbine control system is designed by applying genetic algorithms with reference model to the optimal determination of weighting matrices Q, R that are given by LQ regulator problem. These weighting matrices are optimized simultaneously in the search domain selected adequately. The effectiveness of this boiler-turbine control system is verified by computer simulation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.2
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• pp.226-235
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• 1992

This paper is concerned with the robust control of LQ state feedback regulators with poles in a specified region in the presence of system uncertainty. The robust stability results for the constant and nonlinear time varying perturbations are derived in terms of bounds of the perturbed system matrices and the weighting matrices in the performance index of LQ problem. The theoretical results are applied to the gap control problem of an attractive-type-magnetic levitation system and the effectiveness is proved by the implementation of digital control using 16 bits microcomputer.

• Journal of Advanced Marine Engineering and Technology
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• v.10 no.4
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• pp.31-40
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• 1986

With the tendency toward high speed and high pressure in centrifugal pumps, the problem of sub-synchronous vibration has arisen, caused by the hydraulic forces of the working fluid, such as wearring, balance piston, impeller, etc.. These forces can drastically alter the rotor critical speeds and stability characteristics, and can be acted significant destabilizing forces. For preventing such self-excited vibration, the desing of the rotor system needs, which would secure the stability of the machine. In this paper, a procedure is presented for dynamic modeling of rotor-bearing-seal-impeller systems which consist of rigid disks, distributed parameter finite rotor elements and discrete bearings, seals and impellers. A finite element model including the effects of rotatory inertia and gyroscopic moments is developed using the consistent matrix approach. The technique of dynamic matrix reduction is applied to the shaft matrices to reduce them to a set of matrices of dynamic of significantly fewer degrees of freedom. The representation of bearing, seal and impeller elements is in term of linearized stiffness and damping matrices by reasonably small perturbations from equilibrium. The stability behavior of a typical double suction centrifugal pump is presented. Results show the influence of clearance and flow conditions on running speeds and stability characteristics.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.106-113
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• 2002

A procedure to model and simulate control systems is presented using CADyna and MATLAB/Simulink computer codes. For the plant modeling, a technique for obtaining the state matrices from CADyna is presented. To obtain state matrices from CADyna models, perturbation theory is used. These state matrices are then used in NATLAB to design a controller for the plant. The controller design can subsequently be incorporated into the CADyna model and its closed loop performance is evaluated. Examples are presented to verify the developed methodology.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1199-1204
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• 2007

In a cost based pool market, the generation capacity can be used as strategic bids by generation companies (Gencos) with the cost functions open to the market. Competition using strategic capacities is modeled by Cournot and Perfect Competiton (PC) model, and transformed into two by two payoff matrix game with Gencos' decision variables of Cournot and PC model. The payoff matrices vary when capacity payments are given to Gencos in accordance with their capacity bids. Nash Equilibrium (NE) in the matrices also moves with capacity price changes. In order to maximize social welfare of the market, NE should locate in a certain position of the payoff matrices, which corresponds to a PC NE. A concept of a critical capacity price is proposed and calculated in this paper that is defined as a minimum capacity price leading to PC NE. The critical capacity price is verified to work as a tool for suppressing a strategic capacity withholding in simulations of a test system.