• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.4
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• pp.457-465
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• 2010

In this study, a Taylor series (T-S) model based on the Arrhenius, McVetty, and Monkman-Grant equations was developed using a mathematical analysis. In order to reduce fitting errors, the McVetty equation was transformed by considering the first three terms of the Taylor series equation. The model parameters were accurately determined by a statistical technique of maximum likelihood estimation, and this model was applied to the creep data of alloy 617. The T-S model results showed better agreement with the experimental data than other models such as the Eno, exponential, and L-M models. In particular, the T-S model was converted into an isothermal Taylor series (IT-S) model that can predict the creep strength at a given temperature. It was identified that the estimations obtained using the converted ITS model was better than that obtained using the T-S model for predicting the long-term creep life of alloy 617.

• Journal of the Korean Institute of Telematics and Electronics
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• v.10 no.5
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• pp.21-30
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• 1973

A snaked-line array antenna is investigated for the use of high gain antenna at X-band frequency by studing its attenation constant and the radiation pattern. Attenuation constant which is equivalent to the radiation resistance varies roughly as a function of the square of sinh$\theta$a where sin$\theta$a corresponds to the amplitude of sinusoidal form of snaked-line. The directivity is determined by the number of snaked-line antennas and the periodic units of a snaked line.