• International Journal of Contents
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• 제10권1호
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• pp.23-28
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• 2014

When developing a classifier using various objective functions, it is important to compare the performances of the classifiers. Although there are statistical analyses of objective functions for classifiers, simulation results can provide us with direct comparison results and in this case, a comparison criterion is considerably critical. A Receiver Operating Characteristics (ROC) graph is a simulation technique for comparing classifiers and selecting a better one based on a performance. In this paper, we adopt the ROC graph to compare classifiers trained by mean-squared error, cross-entropy error, classification figure of merit, and the n-th order extension of cross-entropy error functions. After the training of feed-forward neural networks using the CEDAR database, the ROC graphs are plotted to help us identify which objective function is better.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.347-350
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• 1996

With only the classical PID controller applied to control of a DC motor, a good (target) performance characteristic of the controller can be obtained, if all the model parameters of DC motor and operating conditions such as external load torque, disturbance, etc. are exactly known. However, in case when some of system parameters or operating conditions are uncertain or unknown, the fixed PID controller does not guarantee the good performance which is assumed with precisely known system parameters and operating conditions. In view of this and robustness enhancement of DC motor control system, we propose a PID learning controller which consists of a set of learning rules for PID gain tuning and learning of an auxiliary input. The proposed PID learning controller is shown to drive the state of uncertain DC motor system with unknown system parameters and external load torque to the desired one globally asymptotically. Computer simulation results are given to demonstrate the effectiveness of the proposed PID learning controller, thereby showing whose superiority to the conventional fixed PID controller.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.459-468
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• 2009

Analysis of the uncertainty to have engineering solution of gas-dynamic and hydrodynamic problems is based on the comparison the prospective engineering solution with experimental result. In this paper, the mathematical model to estimate heat flux along gas-dynamic channel wall and the solution sequence are shown. Statistical information and generalizing experimental characteristics about gas- and hydro-dynamic channels were applied to the mathematical model. As the results, it is possible to draw a conclusion that models of the integrated approach, using the averaged statistical data of generalizing characteristics for a turbulent flow, without consideration of the turbulent mechanism (characteristic pulsations), can predict a nominal operating regime for gas-dynamic and hydrodynamic systems. The probable deviation of operating regime for newly designed the gas-dynamic channel can achieve 20% from a regime predicted on a basis 1-D or 3-D modelling irrespective of a kind of used models.

• 대한기계학회논문집A
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• 제33권1호
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• pp.42-48
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• 2009

A design methodology for control strategy and control structure gives a direct impact on wind turbine's performance and life cycle. A baseline control law which is a variable rotor speed and variable pitch control strategy is introduced, and a mathematic performance model of a wind turbine dynamics is derived. By using a numeric optimization algorithm, the steady state operating conditions of wind turbines are identified. Because aerodynamic interaction of winds with rotor blades is basically nonlinear, a linearization procedure is applied to analyze wind turbine dynamic variations for whole operating conditions. It turns out the wind turbine dynamics vary much depending on its operating condition.

• 동력기계공학회지
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• 제14권1호
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• pp.27-33
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• 2010

We investigate some operation characteristics and energy efficiency of the BLDC motor system driven by different two types power conversion method depends on same battery source for applying to electrical motor propulsion system of a small ship. Also, we suggest an estimation manner of operating performances such as total running distance and operating speed of ships from basic discharge voltage characteristics of batteries. Through some experiments, direct power conversion was better than indirect method on the view point of energy efficiency and the voltage discharge characteristics could be used as important design factor for estimating operating performances of small ships driven by electrical motors.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제3B권3호
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• pp.139-146
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• 2003

In this paper, the steady-state operating performance analysis for the three-phase squirrel cage rotor self-excited induction generator (SEIG) driven by a variable-speed prime mover (VSPM) in addition to a constant-speed prime mover (CSPM) is presented on the basis of an effective algorithm based on its frequency-domain equivalent circuit. The operating characteristics of the three-phase SEIG coupled by a VSPM and/or a CSPM are evaluated on line processing under the condition of the electrical passive load parameters variations with simple and efficient computation processing procedure in unregulated voltage control loop scheme. A three-phase SEIG prototype setup with a VSPM as well as a CSPM is implemented for the small-scale clean renewable and alternative energy utilizations. The experimental operating characteristic results are illustrated and give good agreements with the simulation ones.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.323-325
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• 1996

The design of Intelligent Energy Saving Power System Controller (IESPSC) for Telecom DC power plants is proposed and presented in this paper. From the past experience. rectifiers for Telecom DC power plants have been operated inefficiently at light loads. IESPSC offers "novel load sharing" approach based on the knowledge of each unit's efficiency of paralleled rectifiers. Neural networks is used for identifying each rectifier's efficiency characteristic curve corresponding to load currents, which is in turn utilized to produce a system efficiency close to the maximum under all operating conditions. In addition, by limiting the number of operating units to the minimum while maintaining high efficiency at the determined loads, a drastic savings in operating cost can be achieved.

• 한국전기전자재료학회논문지
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• 제30권8호
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• pp.520-524
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• 2017

Electrical relay in an essential part of smart grids, electrical vehicles, and LED lightning systems. Therefore, studying relay reliability is important. Relays using permanent magnet actuators (PMAs), which are energy efficient, are also in the spotlight. However, most of the permanent magnets used in PMAs have a characteristic wherein the magnetic flux decreases as the temperature increases. When the magnetic flux is reduced, the force acting on the actuator is reduced. Therefore, in this study, we measured the decrease in the relay operating speed with permanent magnet reduction due to temperature rise. In addition, changes in the bouncing phenomena due to magnetic flux reduction were analyzed. As a result, the operating speed of the relay has decreased and the bouncing phenomenon has not significantly changed.

• 대한임베디드공학회논문지
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• 제6권3호
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• pp.139-148
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• 2011

As the architecture of automotive software is complicated and LOC of software increases, there is an increasing demand for standard operating system. OSEK/VDX defines an industry standard for automotive operating system and middleware. This paper introduces an implementation of RTOS(OSCAR-OSEK) based on OSEK/VDX standard. For better speed of scheduling, we suggest a new method for ready queue implementation considering the characteristic of automotive application software. Also we introduce a method for improving the portability of RTOS on various MCUs. And, we show OSCAR-OSEK implementation and performance test results.

• Journal of the Korean Data and Information Science Society
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• 제19권3호
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• pp.811-818
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• 2008

This paper is the generalization of the modified two-level skip-lot sampling plan(MTSkSP2) to n-level. The general formulas of the operating characteristic(OC) function, average sample number(ASN) and average outgoing quality(AOQ) for the plan are derived using Markov chain properties.