• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.197-199
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• 2003

This paper is Proposed a neural network based estimator for torque and ststor resistance in IPMSM Drives. The neural weights are initially chosen randomly and a model reference algorithm adjusts those weights to give the optimum estimations. The neural network estimator is able to track the varying parameters quite accurately at different speeds with consistent performance. The neural network parameter estimator has been applied to slot and flux linkage torque ripple minimization of the IPMSM. The validity of the proposed parameter estimator is confirmed by the operating characteristics controlled by neural networks control.

• Journal of the Korean Statistical Society
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• v.28 no.4
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• pp.415-433
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• 1999

This paper considers the design of step-stress accelerated life tests for the Weibull distribution with a nonconstant shape parameter under Type I censoring. It is assumed that scale and shape parameters are log-linear functions of (possibly transformed) stress and that a cumulative exposure model holds for the effect of changing stress. The asymptotic variance of the maximum likelihood estimator of a stated quantile at design stress is used as an optimality criterion. The optimum three step-stress plans are presented for selected values of design parameters and the effects of errors in pre- estimates of the design parameters are investigated.

• Journal of Integrative Natural Science
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• v.13 no.3
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• pp.92-96
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• 2020

Taguchi's robust parameter design is an approach to reduce the performance variation of quality characteristics in products and processes. In robust design, the signal-to-noise ratio (SN ratio) was used to find the optimum condition to minimize the variation of quality characteristics as much as possible and bring the average of quality characteristics closer to the target value. In this paper, we propose a simultaneous optimization method based on a linear model of the SN ratio as a method to find the optimal condition of the control factor in case of multi-characteristics. In addition, the proposed method and the existing method were compared and studied by taking actual cases.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.3
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• pp.687-694
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• 1999

In this paper, to draw out the parameter of synchronization for ADSL(Asymmetric Digital Subscriber Line) chip design, we analyze the performance of STR(Symbol Timing Recovery) and frame synchronization with computer simulation. We analyze and design PLL(Phase Lock Loop) loop for ADSL. As a result, we obtained the optimum parameter of STR to design ADSL chip. Also, when performed frame synchronization with several algorithm, we analyzed the performance of FER(Frame Error Rate) and the effect of frame offset with computer simulation.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.121-124
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• 2000

In IMT-2000 systems, the outer loop dynamically adjusts the target SIR so that adequate performance in terms of the frame error rate(FER) and the true quality measure is achieved. This paper utilizes an analytic model lot outer loop power control(OLPC) adjusting the target SIR in IMT-2000. The analytic model is based on the discrete-time Markov chain as voice traffic SIR. It is described that the model can be used to find the optimum step size in voice traffic for fast fading environments. The optimum step size influences the performance of OLPC： As the step size decreases, the average target SIR increases and average FER decreases.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1796-1802
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• 2000

The purpose of this work is to analyze the vibration characteristic of boring bar with dynamic vibration absorber and find out the effective design parameters. Using the finite element method and modified optimum design concept, conventional optimum design based on approximate lumped parameter model is checked and practical design to be measured with modal analysis is compared with optimum design from numerical analysis. Also, the performance of reducing vibration is investigated with variation of shape of boring bar. The considered model of boring bar with dynamic vibration absorber is selected among manufactured boring bars with the best performance.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.3
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• pp.159-165
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• 2008

This paper deals with the optimum high pressure control algorithm for a transcritical $CO_2$ mobile air-conditioning system with belt-driven compressor to achieve the maximum COP. The experiments were performed to find out the maximum COP conditions with various operating conditions. The experimental results showed that the COP was increased and then decreased with increase of the refrigerant high pressure for the system. Therefore the value of high pressure which has maximum COP could be selected. Furthermore, the strong (linear) relation between the optimum high pressure and the gas cooler outlet temperature was revealed, which suggests the use of a simple controller with only one parameter for the transcritical $CO_2$ cycle.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.1
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• pp.16-27
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• 1996

Using computer in design is a trend in recent years. A good suspension model is depend on the carefully prepared data like joint connection points or spring stiffness, etc. Once a good computer model is obtained, a parametric study for spciffic suspension design factor, like a toe angle, can be done to obtain sensitivity information. Using this information, several important design parameters for a specific design factor can be identified. Once a design of experiments is done using computer models, the results can be used to approximate a function which can best represent the experimentation. An optimum solution of this function can be used to find an optimum design of a suspension system for a specific suspension design factor. Same method is again applied to other design factors iteratively until a good suspension system design is obtained.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.2
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• pp.189-199
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• 2000

This paper investigates the thermodynamic performance of latent heat thermal energy storage system using two phase change materials(2-PCM system). The thermodynamic merit of using 2-PCM is clear in terms of exergetic efficiency, which is substantially higher than that of 1-PCM system. Optimum phase change temperature to maximize the exergetic efficiency exists for each case. The heat transfer area ratio of high temperature storage unit, X, becomes another important parameter for 2-PCM system if the phase change temperatures of given materials are different from those of optimum conditions. It is a good approximation for X$_{opt}$ to be 0.5 when optimum phase change temperatures are used. Otherwise X$_{opt}$ is determined differently as a function of given phase change temperatures.res.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.2 no.1
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• pp.49-62
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• 1990

The forced cooling system has been widely applied to passing more electric current in the underground power transmission cable technology. In this paper, the optimum cooling span of the in-trough-indirect water cooling method within an electric tunnel was investigated. A parametric study was performed for the cable currents, the coolant flow rates, and the coolant inlet temperatures. As a result, the temperature of the inlet air has been found as the most important parameter in determination of the optimum cooling span.