• Journal of the Korean Data and Information Science Society
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• v.26 no.4
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• pp.907-914
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• 2015

Reduction in the number of students due to the low birth rate has notice very many changes in the national education policies. The purpose of this study is to propose a method for estimation of the number of students (the population) by age or grade promotion rate of progression rate to estimate the exact number of students (the population) by 2032. It was suggested the nth moving average proportional method and the weighted proportional moving average method as the method of population projections. It presents the means and standard deviations of the measurement errors of the suggested methods by Monte Carlo simulation. Measured in this study are predicted result was a phenomenon is estimated lower than the actual value.

• Journal of Welding and Joining
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• v.15 no.1
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• pp.81-91
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• 1997

In this study, a magnetic sensor to make use of eddy current was developed to detect the weld seam of butt joint in the sheet metal arc welding. This system consist of the sensor device for detecting the weld line, the servo control device for driving the weld torch movement and the control unit. A signal processing was applied to smooth the output signal of the sensor. The weld joint was determined by using a 1st order differential method. To improve tracking accuracy of the system, moving average method which has an effect of proportional and weighted integral control was applied to a series of the weld joint positions obtained above. The weld line for tracking was generated by using data regeneration algorithm. Based on these results, each servo motor was controlled by pulse generator. From experimental results, it was revealed that this system has excellent detecting ability for weld line and seam tracking ability.