• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1061-1062
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• 2006

This paper represent improved On-line Turn off, commutation Angle control schemes for switched reluctance motors based on current control. For the purpose of the finding optimal commutation switching angle point, it is utilized turn on and turn off position calculation with inductance vs. current vs. flux linkage analysis method. The goal of proposed paper is the maximization of the energy conversion per stroke and maximizing efficiency and obtaining approximately flat-topped current waveform. The proposed control scheme is demonstrated on a simulation experimental result.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.3
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• pp.68-76
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• 1994

In the automatic transistor sizing with computer for optimizing delay and the chip area of CMOS digital circuits, conventionally either a mathematical method or a heuristic method has been used. In this paper, we present a new method of transistor sizing, a sort of combination of the above two methods, in which the mathematical method is used for sizing of critical paths and the heuristic method is used for desizing of non-critical paths. In order to reduce the overall problem dimension, a basic block called an extended stage is introduced which includes a basic stage, parallel transistors and complementary part. Optimization for multiple critical paths is formulated as a problem of area minimization subject to delay constraints and is solved by the augmented Lagrange multiplier method. The transistor sizes along non-critical paths are decreased successively without affecting the critical path delay times. The proposed scheme was successfully applied to several test circuits.

• Earthquakes and Structures
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• v.1 no.3
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• pp.307-326
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• 2010

This paper is concerned with the optimal seismic design of added viscous dampers in yielding plane frames. The total added damping is minimized for allowable values of local performance indices under the excitation of an ensemble of ground motions in both regular and irregular structures. The local performance indices are taken as the maximal inter-story drift of each story and/or the normalized hysteretic energy dissipated at each of the plastic hinges. Gradients of the constraints with respect to the design variables (damping coefficients) are derived, via optimal control theory, to enable an efficient first order optimization scheme to be used for the solution of the problem. An example of a ten story three bay frame is presented. This example reveals the following 'fully stressed characteristics' of the optimal solution: damping is assigned only to stories for which the local performance index has reached the allowable value. This may enable the application of efficient and practical analysis/redesign type methods for the optimal design of viscous dampers in yielding plane frames.

• Water for future
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• v.23 no.4
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• pp.421-434
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• 1990

The problems of hydrologic similarity among river basins was analyzed by a geomorphologic response model using Hortons*s ordering scheme. The Nash model was used for deriving the geomorphologic response function, and for the optimization of the responsefunction, imcomplete gamma function andRosso*s regression equation were used. The application of this method was tested on some observed flood data of Pyungchang river basin and Wi Stream basin and Bocheong stream, and predictions of hydrologic response were compared with that of the Moment method. The results show that the proposed model and dimensionless instantaneous unit hydrograph can be used for the runoff analysis of an ungauged basin and the analysis of hydrologic similarity.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.10a
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• pp.349-352
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• 2004

In this paper, we propose a newly energy-efficient routing protocol, which is called Maximum Utility Routing(MUR), in mobile ad hoc networks (MANETs) so as to investigate the minimum energy and maximum lifetimes issues together. We present a utility-based framework so as to meet various incompatible constraints simultaneously and fairly. To explore this issue, we use the concepts and mathematics of microeconomics and game theory. Though simulation results, we show that our routing scheme has much better performance especially in terms of network efficiency, network lifetime, and average power consumption.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.571-572
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• 2006

A simulation tool for design space exploration of a real-time reconfiguration system was developed in this paper. We described an algorithm for a partial real-time reconfiguration to utilize already existing configured functional units and applied it to H.263 encoder application. This scheme allows us to find a starting configuration for the further optimization without actually building a prototype.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.2
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• pp.373-381
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• 2009

In this paper, a humanoid robot is simulated and implemented to walk up a staircase using the blending polynomial and genetic algorithm. Using recently developed kinematics for a biped robot, four schemes for walking up a staircase are newly proposed and simulated separately. For the two schemes of landing a swaying leg on the upper stair, the joint trajectories of seven motors are particularly optimized to generate an energy-minimal motion with the guarantee of walking stability. The proposed scheme of walking upstair is validated by an experiment with a small humanoid robot.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2238-2243
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• 2008

The use of arc tubes made of ceramic material further enhanced some of the metal halide lamp's properties. These properties translate into higher efficacy with better color rendering, stable color through lamp long life. Recently, due to an increase in the application of the ceramic metal-halide lamp, the study for the property etc. according to Ballast's driving scheme and the study for arc tube material, optimization of gas and so on are being proceeded to improve the property of the lamp. Especially, to control ceramic metal-halide lamp, the vigorous study and practical use with respect to Electronic Ballast, which has been improved in the disadvantages of the conventional Magnetic Ballast are made. In this paper, Electrical, optical and thermal characteristics are analyzed by comparing magnetic ballast with electronic ballast.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.179-181
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• 1999

Sensorless PMSM is much studied for the industrial applications and home appliances because a mechanical sensor reduce reliability and increases cost. Most of sensorless algorithm have poor performances in a low speed range. This paper investigates Performance improvement in a low speed range of PMSM. The proposed control scheme is based on the optimization of ratio between the command and dc-link voltages. The experiment is performed in this study. and the result shows the improved Performance in a low speed range.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2386-2388
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• 2000

This paper proposes a novel method with pseudo-on-line scheme using look-up table based on the genetic algorithm. The technique is a pseudo-on-line method that optimally estimate the parameters of fuzzy PID(FPID) controller for systems with non-linearity using the genetic algorithm which does not use the gradient and finds the global optimum of an un-constraint optimization problem. The proposed controller(GFPID) is applied to speed control of 3-phase induction motor and its computer simulation is carried out. Simulation results show that the proposed method is more excellent than conventional FPID and PID controllers.