• The Journal of Korean Association of Computer Education
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• v.6 no.3
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• pp.65-73
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• 2003

Most web-based learning is furnishing single side and consistent training resource to learner. Research was gone to apply item analysis method or to introduce web-based learning system using studying pattern. But, we need complicated algorithm or parameter setting etc, for apply these method. Therefore, in this research, we design and implement an item selection system in consideration of learner's incorrectness rate and problem frequency selection rate about question of item selection attribute. Also, as that embody business logic about item selection by EJB, efficient system development is available and we improved maintenance and reusability.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.7
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• pp.883-888
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• 2014

The paper describes the parameter tuning of power system stabilizer (PSS) for a power plant based on hybrid system modeling. The existing tuning method based on bode plot and root locus is well applied to keep power system stable. However, due to linearization of power system and an assumption that the parameter ratio of the lead-lag compensator in PSS is fixed, the results cannot guarantee the optimal performances to damp out low-frequency oscillation. Therefore, in this paper, hybrid system modeling, which has a DAIS (differential-algebraic-impusive-switched) structure, is applied to conduct nonlinear modeling for power system and find optimal parameter set of the PSS. The performances of the proposed method are carried out by time domain simulation with a single machine connected to infinite bus (SMIB) system.

• Computers and Concrete
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• v.30 no.4
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• pp.269-276
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• 2022

In this paper, frequency vibrations of double-walled carbon nanotubes (CNTs) has been investigated based upon nonlocal elastic theory. The inference of small scale is being perceived by establishing nonlocal Love shell model. The wave propagation approach has been operated to frame the governing equations as eigen value system. An innovational nonlocal model to examine the scale effect on vibrational behavior of armchair, zigzag and chiral of double-walled CNTs. An appropriate selection of material properties and nonlocal parameter has been considered. The influence of dimensionless nonlocal parameter has been studied in detail. The dominance of end condition via nonlocal parameter is explained graphically. The results generated furnish the evidence regarding applicability of nonlocal shell model and also verified by earlier published literature.

• Journal of the Korean Statistical Society
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• v.30 no.3
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• pp.453-465
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• 2001

It is often the case that one wants to estimate parameters of the distribution which follows certain parametric model, while the dta are contaminated. it is well known that the maximum likelihood estimators are not robust to contamination. Basuet al.(1998) proposed a robust method called the minimum density power divergence estimation. In this paper, we investigate data-driven selection of the tuning parameter $\alpha$ in the minimum density power divergence estimation. A criterion is proposed and its performance is studied through the simulation. The simulation includes three cases of estimation problem.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.3
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• pp.293-300
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• 2007

The aim of this paper is to design a speed controller of a DC motor by selection of a PID parameters using genetic algorithm. The model of a DC motor is considered as a typical non-oscillatory, second-order system, And this paper compares three kinds of tuning methods of parameter for PID controller. One is the controller design by the genetic algorithm. second is the controller design by the model matching method third is the controller design by Ziegler and Nichols method. It was found that the proposed PID parameters adjustment by the genetic algorithm is better than the Ziegler & Nickels' method. And also found that the results of the method by the genetic algorithm is nearly same as the model matching method which is analytical method. The proposed method could be applied to the higher order system which is not easy to use the model matching method.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.6
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• pp.683-691
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• 1999

In this paper, it is suggested that the selection method of optimal parameter of power system stabilizer(PSS) with robustness in low frequency oscillation for power system using Real Variable Elitism Genetc Algorithm(RVEGA). The optimal parameters were selected in the case of power system stabilizer with one lead compensator, and two lead compensator. Also, the frequency responses characteristic of PSS, the system eigenvalues criterion and the dynamic characteristic were considered in the normal load and the heavy load, which proved usefulness of RVEGA compare with Yu's compensator design theory.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.181-184
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• 2003

Recently, the fieldbus becomes an indispensable component for many automated systems. In the fieldbus system, realtime data containing sensor values and control commands has a tendency to rapidly lose its value as time elapses after its creation. In order to deliver these data in time, the fieldbus network should be designed to have short delay compared to the maximum allowable delay. Because the communication delay is affected by performance parameters such as target rotation timer of token passing protocol, it is necessary to select proper parameter settings to satisfy the real-time requirement for communication delay. This paper presents the timer selection method for Profibus token passing networks using genetic algorithm (GA) to meet the delay requirements.

• Journal of Korean Society for Quality Management
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• v.11 no.2
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• pp.18-24
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• 1983

In this paper, subset selection procedures are proposed for selecting the Weibull population with the smallest scale parameter out of k Weibull populations with a common shape parameter. The proposed procedures are based on the maximum likelihood estimators. The constants to implement the procedures are tabulated using Monte Carlo methods. Also, the results of a comparison study are given.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.3
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• pp.83-90
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• 2001

This paper resents an algorithm for the optimal parameter selection of a power system stabilizer in a single machine-infinite bus system through the external equivalent transmission line. This method is one of the classical techniques by changing the PSS gain to allocate properly pole-zero positions. All the PSS parameters are obtained by solving a set of algebraic equations for the system constants depend on a variety of machine loadings and system external impedances, the natural oscillation modes, and the damping characteristics. And this algorithm was written in a simple software program using MATLAB.

• Near Infrared Analysis
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• v.1 no.1
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• pp.1-7
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• 2000

A convenient algorithm for optimizing wavelength selection in multiple linear regression (MLR) has been developed. MOP (MLP Optimization Program) has been developed to test all possible MLR calibration models in a given spectral range and finally find an optimal MLR model with external validation capability. MOP generates all calibration models from all possible combinations of wavelength, and simultaneously calculates SEC (Standard Error of Calibration) and SEV (Standard Error of Validation) by predicting samples in a validation data set. Finally, with determined SEC and SEV, it calculates another parameter called SAD (Sum of SEC, SEV, and Absolute Difference between SEC and SEV: sum(SEC+SEV+Abs(SEC-SEV)). SAD is an useful parameter to find an optimal calibration model without over-fitting by simultaneously evaluating SEC, SEV, and difference of error between calibration and validation. The calibration model corresponding to the smallest SAD value is chosen as an optimum because the errors in both calibration and validation are minimal as well as similar in scale. To evaluate the capability of MOP, the determination of benzene content in unleaded gasoline has been examined. MOP successfully found the optimal calibration model and showed the better calibration and independent prediction performance compared to conventional MLR calibration.