• Water for future
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• v.29 no.1
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• pp.151-161
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• 1996

The proposed flood forecasting system combines a flood routing model with a parameter estimation model. In the parameter estimation model system states and parameters are treated with the extended state-space formulation. The extended Kalman filter is adopted to estimate the states and parameters. A sensitivity analysis is used to investigate the relative significance of the parameters. Insensitive parameters are treated as constants and parameters that are mutually correlated are combined in a simplified form. The developed estimation methodology is applied todam sites of the multi-purpose reservoirs in Korea. The forecasted hydrographs from the extended Kalman filter satisfactorily coincide with the observed. From the time sequence plots of estimated parameters, it is found that the storage coefficient is almost constant, but exponent varies appreciably in time.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.4
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• pp.55-61
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• 1995

Variable structure control (VSC) can be used for the control of power plants required stability and robustness such as elevator control. It has no overshoot and is insensitive to parameter variations and disturbances in the sliding mode where the system structure is changed with the sliding surface in the center. But in the real system, VSC has a high frequency chattering which has a bad influence upon the control system proformances. In this paper, to alleviate the high frequency chattering, a binary controller (BC) with inertial type external loop is implemented by DSP and applied to position control of brushless DC motor. Binary controller has external loop to generate the continuous control input with the flexible variation of primary loop gain. Thus it has the property of chattering alleviation in addition to advantages of the conventional variable structure control.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.409-413
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• 2001

This paper presents a comprehensive study result on reducing commutation torque ripples generated in brushless dc motor drives with only a single dc-link current sensor provided. In brushless dc motor drives with only a single current sensor, the commutation torque ripple suppression that is practically effective in low speed as well as high speed regions has not been reported. A proposed commutation compensation technique based on deadbeat dc-link current controller takes a closed loop control scheme and a parameter insensitive property. The proposed control method is verified through simulations and experiments.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.404-408
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• 2001

This paper deals with speed control of induction motors with a gain tuning based on simple Genetic Algorithms, which are search algorithms based on the mechanics of natual selection and genetics. Based on the designed control system structure, the indirect vector control system of induction motors is simulated. The simulation results show that the system has a strong robust to the parameter variation and is insensitive to the load disturbance. Thus, the proposed PI controller based on genetic algorithms is superior to manually tuned classical PI controller in improving the speed control performance of induction motors.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1114-1119
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• 2002

In this paper, the well-conditioned observer is designed to be insensitive to the ill-conditioning factors in transient and steady-state observer performance. A condition number based on 12-norm of the eigenvector matrix of the observer matrix has been proposed on a principal index in the observer performance. For the well-conditioned observer design, the non-normality measure and the observability condition of the observer matrix are utilized. The two constraints are specified into observer gain boundary region that guarantees a small condition number and a stable observer. The observer gain selected in this region guarantees a well-conditioned and observable property. In this study, this method is applied to the Luenberger observer and Kalman filters for small order systems. In designing Kalman filters, the ratio of the process noise covariance to the measurement noise covariance is a design parameter and its effect on the condition number is investigated.

• Journal of Korean Society for Quality Management
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• v.20 no.1
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• pp.68-79
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• 1992

The economic order quantity(EOQ) is a robust quantity, and it is largely insensitive to reasonable errors in the estimation of most of its parameters. Optimal EOQ and reorder point which are not sensitive to the estimates of the various cost model parameters for Kim and Park's model are determined. This of Taguchi's parameter design which finds a robust EOQ and reorder point using reasonable cost structure on the assumption of normally distributed quality characteristic. A numerical example is also presented to illustrate the proposed procedure and computer aided numerical experiments for selected values of backordered fractions and standard deviations are performed.

• Journal of Korean Institute of Industrial Engineers
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• v.17 no.1
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• pp.95-108
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• 1991

For the case where the lifetime at a constant stress level has exponential distribution, optimal accelerated life test plans are developed under the assumptions of intermittent inspection and Type I censoring. In a optimal plan, the low and high stress levels, the proportion of test units allocated and the inspection times at each stress are determined such that the asymptotic variance of the maximum likelihood estimator of logarithmic transformed mean at the use condition is minimized. In addition to the optimal plan in which numerical technique to solve the set of nonlinear equations must be employed to determine inspection times at each stress level, we also propose another plans which employ equally-spaced or equal probability inspection schemes at two overstress levels of corresponding optimal one. For both optimal and proposed plans, computational results indicate that the asymptotic variance of the estimated mean at the use stress is insensitive to number of inspections at overstress levels for the range of parameter values considered.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.313-318
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• 2001

In this paper, the well-conditioned observer is designed to be insensitive to the ill-conditioning factors in transient and steady-state observer performance. A condition number based on $L_2-norm$ of the eigenvector matrix of the observer matrix has been proposed on a principal index in the observer performance. For the well-conditioned observer design, the non-normality measure and the observability condition of the observer matrix are utilized. The two constraints are specified into observer gain boundary region that guarantees a small condition number and a stable observer. The observer gain selected in this region guarantees a well-conditioned and observable property. In this study, this method is applied to the Luenberger observer and Kalman filters. In designing Kalman filters for small order systems, the ratio of the process noise covariance to the measurement noise covariance is a design parameter and its effect on the condition number is investigated.

• Journal of Electrical Engineering and Technology
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• v.3 no.1
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• pp.29-35
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• 2008

With long time setting, zone 3 impedance relays are considered insensitive to power swings, and their operation condition during power swings is seldom analyzed. Instead of ti me-consuming simulation to the swing loci, their operation condition is directly quantified by polynominal functions in this paper to find the critical swing angle and frequency for relay operation under different relay settings and system parameters. It is found: (1) the swing loci are more densely populated inside than outside of the protection region, which corresponds to long residence time and possible relay operations; (2) the relays may be sensitive to load encroac hments and stable power swings with different relay settings and system parameters; (3) the critical swing frequency may be in the range of low-frequency power swings.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.10 s.352
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• pp.61-67
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• 2006

We developed a constant current source which is insensitive to threshold voltage variation caused by irregular grain boundary distribution in polycrystalline silicon. The proposed current source has superior saturation characteristics over wide range of input voltages as well as small current error compared to the previously reported Vth compensated sources. We measured the circuit performance and error in current due to parameter variation by using HSPICE.