• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.8
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• pp.1515-1517
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• 2015

The effects of the reference sample size on the detection probability of the two-sample rank detector is investigated in this paper. The larger reference sample size shows the better performance of the detector. The effect is also shown to be saturated as the reference sample size becomes larger.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.8
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• pp.924-931
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• 1999

Most conventional protection relays are based on processing information in the spectrum that is close to or at power frequency. It is, however, widely known that faults on transmission lines produce frequency components of a wide range. High frequency signals caused by sudden changes in system voltage that occurs in the immediate post-fault period are generally outside the bandwidth of receptibility of most protection scheme. In this respect, a specially designed stack tuner is connected to the coupling capacitor of CVT, in order to capture the high frequency signals. Digital signal processing is then applied to the captured information to determine whether the fault is inside or outside the protected zone, and to discriminate the fault type. In this paper, modal transform is not applied to fault generated signals, because signals which are converted by modal transform are not have an information of each phase any longer. Instead, using peak voltage value of data windows is able to discriminate fault type. The paper concludes by presenting fault detection and discrimination of various faults on transmission line which are based on extensive simulation studies carried out on a typical 154kV Korean transmission line, using the EMTP software.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.442-445
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• 1992

Optical type hydrometer has been designed and constructed utilizing the fact that the refractive index of solution is varied in accordance with its specific gravity. Optical hydrometer produces the electric singal output with reflection of light in accordance with its specific gravity. This can be applied to continuous monitoring and/or automatic control of the specific gravity of solution. U-shaped glass rod was used a transfer medium of light, and the electronic circuit which utilize phase sensitive detection technique was designed to measure accurately the intensity of light. The specific gravity of sulfuric acid was measured with this hydrometer and the results show good linearity of output signal with its specific gravity.