• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.6
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• pp.1001-1009
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• 1994

The present paper deals with a new developed sensor for measuring the time-varying magnetic fields and describes the experimental results of trasient magnetic field that takes place during the operations of electric appliance. The operation principle of the self-integrating magnetic field sensor by using coaxial cable is analyzed and a calibration investigation is carried out. The frequency bandwidth of the magnetic field measurement system is from 40 Hz to about 300 kHz. The magnetic field induced by the starting and/or operation of electric appliance mainly includes the odd harmonics such as the third, the fifth and the seventh harmonics. The magnetic field intensity caused during the operation of ultrasonic washer is inversely proportional to distance, this correspodns to induction component. As a result, it was known that the odd harmonics of magnetic field in the desing of electromagnetic shield employed for protecting electronic circuit and control devices have to be considered.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.71-74
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• 1995

In this paper, a new PID fuzzy controller(FC) based on parallel operation of PI and PD fuzzy control is presented. First, two fuzzy rule bases are constructed by separating the linguistic control rule for PID FC into two parts : one is e-.DELTA.e part, and the other is .DELTAL.$^{2}$e-.DELTA.e part. And then two FCs employing these rule bases indivisually are synthesized and run in parallel. The incremental control input is determined by taking weighted mean of the outputs of two FCs. The proposed PID FC improves the transient response of the system and gives better performance than the conventional PI FC.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.1
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• pp.68-78
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• 1997

A numerical study on the transient vapor flow and heat transfer is performed to investigate the ideal switching operation of heat source in a high temperature heat pipe. The cylindrical 2-dimensional compressible laminar vapor flow is assumed for the vapor space and the conjugate heat transfer for the heat pipe wall, wick and vapor space is calculated. The different boundary conditions such as constant heat flux, convective or radiative boundary at the outer wall are used respectively to compare the influence of boundary conditions on the transient operation. The transient temperature profile and the internal flow of the entire pipe for the switching operation are described as a result. The results show that the transient time is not significantly affected by the boundary conditions at the outer wall in present study. During the transition, two independent flows are observed temporarily on the right side and left side of the heat pipe. It is also found that the trend of temperature variation in the vapor region is different from the variation in the wick and wall region.