• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.157-160
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• 1992

An approximate method for the dominant eigenvalue of one machine connected to the infinite bus has been suggested. This method is based on combining the traditional eigenvalue sensitivity analysis and the structure of the system state matrix. Numerical examples are presented. This method is considered to be quite useful in the stability analysis for various initial conditions and for adjustment of generator controller parameters.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.189-191
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• 1993

A systematic procedure for the elements of system matrix in multimachine systems with loads is suggested for the small-signal stability studies. Synchronous machines are represented by either a two-axis model or classical model. The interrelationship of submatrices of system matrix is investigated. Once elements of one submatrix are determined, they can be used to calculate the elements of the other submatrix. It is illustrated for three machine and nine bus multimachine systems with constant impedance loads, constant MVA load, constant current and power factors.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.2
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• pp.75-80
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• 2004

Vehicle structures are composed of many substructure connected to one another by various types of mechanical joints. In vehicle engineering it is important to study these connected structures under various dynamic forces for the evaluations of fatigue life and stress concentration exactly. It is difficult to obtain the accurate load history of specified positions because of the errors such as modeling, measurement and etc. In the beginning of design exact load data are actually necessary for the fatigue strength and life analysis to minimize the cost and time of designing. In this paper, the procedure of practical dynamic force determination is developed by the combination of the principal stresses of F. E. Analysis and experiment. Least square pseudo inverse matrix is adopted to obtain in inverse matrix of analyzed stresses matrix. The error minimization method utilizes the inaccurate measured error and the shifting error that the whole data is stiffed over real data. The least square criterion is adopted to avoid these non. Finally, to verify the proposed procedure, a bus is analyzed. This measurement and prediction technology can be extended to the structural modification of any geometric shape in complex structure.

• Science of Emotion and Sensibility
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• v.5 no.2
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• pp.63-72
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• 2002

In order to examine universal design, 1 have developed two analytical methodologies based on 3P(point) task analysis: structured task analysis and task matrix analysis. I also extracted nine universal design items, namely (1) adjustment, (2) redundancy, (3) specification and function transparency, (4) feedback and (5) error tolerance, (6) effective acquisition of information, (7) ease of understanding and judgment, (8) comfortable operation, and (9) continuity of information and operation. Structured task analysis is used to uncover problems in each of the tasks constituting a job for each functionally challenged condition of users, and solutions to the extracted problems are examined in terms of the above-mentioned nine universal design items. Task matrix analysis calls for the production of a table for each task in a job. In each table, nine items form the columns, and the horizontal rows list all disability types. Then, solutions are formulated for each cell formed by the intersecting columns and rows. Using these two analysis methods, 1 have conducted a verification experiment for the universal design of a public bus. The results of the research have enabled me to propose various ,solutions from a system-based perspective, instead of coming up with the superficial and isolated solutions which are normally produced when conventional analytical methods are used.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.05a
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• pp.144-151
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• 2002

In order to examine universal desist I have developed two analytical methodologies based on 3P(point) task analysis: structured task analysis and task matrix analysis. I also extracted me universal design items, namely (1) adjustment (2) redundancy, (3) specification and function transparency, (4) feedback and (5) error tolerance, (6) effective acquisition of information, (7) ease of understanding and judgment (8) comfortable operation, and (9) continuity of information and operation. Structured task analysis is used to uncover problems in each of the tasks constituting a job for each functionally challenged condition of users, and solutions to the extracted problems are examined in terms of the above-mentioned nine universal design items. Task matrix analysis calls for the production of a table for each task in a job. In each table, nine items from the columns, and the horizontal rows list all disability types. Then, solutions are formulated for each cell formed by the intersecting columns and rows. Using these two analysis methods, T have conducted a verification experiment for the universal design of a public bus. The results of the research have enabled me to propose various solutions from a system-based perspective, instead of coming up with the superficial and isolated solutions which are normally produced when conventional analytical methods are used.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.3
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• pp.437-443
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• 2009

In recent years, electric power systems have been experiencing a rapid change due to the increasing electricity market. For the effective use of power system under the deregulated environment, it is important to make a fast and accurate calculation of the maximum available transfer capability (ATC) from a supply point to a demand point. In this paper, the purpose of this research is to calculate ATC fast and accurately for securing the stability of system and raising the efficiency as a result of anticipating transmission congestion according to transmission open access progressed in the future under the regulated environment of electricity market. In this paper, a study utilized a relation of the potential energy and energy function by which calculated CCT and then utilized a relation of PEBS for transient stability ATC calculation. In this paper, ATC was calculated as RPF and Energy Function method and calculation results of each method was compared. Contingence ranking method decided the weak bus by the Eigenvalues of Jacobian matrix and overloading branches by PI-index. As a result, a study proved the fast and accurate ATC calculation method considering transient stability suggested in this paper. Through the case study using New England 39 bus system, it is confirmed that the proposed method can be used for real time operation and the planning of electric market.

• International Journal of Control, Automation, and Systems
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• v.3 no.spc2
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• pp.322-333
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• 2005

This paper proposes a combination of the Thyristor Controlled Series Capacitor (TCSC) and Static Var Compensator (SVC) installation for enhancing the damping performance of a power system. The developed scheme employs a damping controller which coordinates measurement signals with control signals to control the TCSC and SVC. The coordinated control method is based on the application of projective controls. Controller performance over a range of operating conditions is investigated through simulation studies on a single-machine infinite-bus power system. The linear analysis and nonlinear simulation results show that the proposed controller can significantly improve the damping performance of the power system and hence, increase its power transfer capabilities. In this paper, a current injection model of TCSC is developed and incorporated in the transmission system model. By using equivalent injected currents at terminal buses to simulate a TCSC no modification of the bus admittance matrix is required at each iteration.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.523-526
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• 1995

This paper presents an improved algorithm of optimal measurement system design with a reliability evaluation method for a large power system. The proposed algorithm is developed to cosider the observability and to achieve highest accuracy of the state estimator as well with the limited investment cost. When the effect on these dummy bus measurements is considered in the proposed algorithm the other errors in the power system is also detected and then analyzed until to achieve the limited values. By taking advantage of the matrix sparsity and the optimal bus ordering the memory and the time are successfully reduced in the P/C's and workstation's model. The improved program is successfully tested for IEEK sample system and KEPCO system with PSS/E lineflow calculated data package.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.4
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• pp.168-176
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• 2000

This paper presents the Hessenberg method, a new sparsity-based small signal stability analysis program for large interconnected power systems. The Hessenberg method as well as the Arnoldi method computes the partial eigen-solution of large systems. However, the Hessenberg method with pivoting is numerically very stable comparable to the Householder method and thus re-orthogonalization of the krylov vectors is not required. The fractional transformation with a complex shift is used to compute the modes around the shift point. If only the dominant electromechanical oscillation modes are of concern, the modes can be computed fast with the shift point determined by Fourier transforming the time simulation results for transient stability analysis, if available. The program has been successfully tested on the New England 10-machine 39-bus system and Korea Electric Power Co. (KEPCO) system in the year of 2000, which is comprised of 791-bus, 1575-branch, and 215-machines. The method is so efficient that CPU time for computing five eigenvalues of the KEPCO system is 3.4 sec by a PC with 400 MHz Pentium IIprocessor.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.12
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• pp.1-11
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• 1998

A line profile synthesis method is presented that minimizes the nearest-neighbor crosstalk peak level for high-speed pulse transmission in multi-coupled microstrip signal buses. We adopted the optimization technique for the reflected wave control on bus lines resulting in increasing the average spacing between strip conductors, since in a parallel-conductor bus the crosstalk energy is concentrated at the nearest neighbors of the driven line. The generalized S-matrix technique is applied for the input and output waveform prediction, and crosstalk characteristics of various nonuniform lines synthesized for increasing the average spacing are analyzed by comparing each other. Simulation results demonstrate that the Chebyshev taper with dips is adequate to significantly minimize the crosstalk peak level under the satisfactory waveform integrity since the profile is oriented to evenly reflect significant pulse spectra within the frequency range of pulse.