• Journal of the Korean Statistical Society
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• v.35 no.3
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• pp.225-238
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• 2006

This paper considers noninformative priors for the scale parameter of exponential distribution when the data are collected in step stress accelerated life tests. We find the Jeffreys' and reference priors for this model and show that the reference prior satisfies first order matching criterion. Also, we show that there exists no second order matching prior in this problem. Some simulation results are given and we perform Bayesian analysis for proposed priors using some data.

• Journal of the Korean Statistical Society
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• v.36 no.1
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• pp.77-91
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• 2007

This paper considers development of noninformative priors for the familial data when the families have equal number of offspring. Several noninformative priors including the widely used Jeffreys' prior as well as the different reference priors are derived. Also, a simultaneously-marginally-probability-matching prior is considered and probability matching priors are derived when the parameter of interest is inter- or intra-class correlation coefficient. The simulation study implemented by Gibbs sampler shows that two-group reference prior is slightly edge over the others in terms of coverage probability.

• Journal of the Korean Data and Information Science Society
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• v.15 no.3
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• pp.677-687
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• 2004

We consider the comparison of two one-parameter exponential distributions with the complete data as well as the type II censored data. We adapt Bayesian test procedure for nested hypothesis based on the Bayesian reference criterion. Specifically we derive the expression for the Bayesian reference criterion to solve our problem. Also we provide numerical examples using simulated data sets to illustrate our results.

• Journal of the Korean Data and Information Science Society
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• v.16 no.1
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• pp.71-78
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• 2005

Recently an important issue in Bayesian methodology is determination of noninformative prior distributions, often required when there is no idea of prior information. In this thesis attention is focused on the development of noninformative priors for stationary AR(1) model. The noninformative priors primarily discussed are the Jeffreys prior, and the reference priors. The remarkable points in the result are that the Jeffreys prior coincides with the reference prior for the case that $\rho$ is the parameter of interest.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.6
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• pp.219-224
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• 1983

The problem of model reference adaptive control for the discrete time system is considered and the global stability of the overall system is shown. It extends the results of Kreisselmeier's to more general reference models and the method presented here makes the output error and controller parameter error converge to zero. The scheme presented in this paper is simulated and the simulation gives the expected results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.2122-2129
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• 2002

Creep damage using a reference stress(RS) was analyzed for type 316LN stainless steel. The generalized K-R equation was reconstructed into the RS equation using a critical stress value $\sigma$. The RS equation was derived from the critical stress in failure time $t_f$ instead of material damage parameter $\omega$, which indicates the critical condition of collapse or approach to gross instability of materials during creep. For obtaining the reference stress, a series of creep tests and tensile tests were conducted with at 55$0^{\circ}C$ and $600^{\circ}C$. The stress-time data obtained from creep tests were applied to the RS equations to characterize the creep damage of type 316LN stainless steel. The value of creep constant r with stress levels was about 18 at 55$0^{\circ}C$ and 21 at $600^{\circ}C$. This value was almost similar with r = 24 in the K-R equation, which was obtained by using damage parameter $\omega$. Relationship plots of creep failure strain and life fraction $(t_f /t_r)$ were also obtained with different λ values. The RS equation was therefore more convenient than the generalized K-R equation, because the measuring process to quantify the damage parameter $\omega$ such as voids or micro cracks in crept materials was omitted. The RS method can be easily used by designers and plant operator as a creep design tool.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.3
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• pp.206-213
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• 1998

In this paper, an adaptive compensation technique for parameter variation is proposed which can perform quick torque response in vector control of an induction motors. To solve the problem of control performance degradation due to parameter variation in an induction motor, a rotor resistance estimation is performed by the model reference adaptive control(MRAC). The algorithm of rotor resistance estimation is composed of the error relationship which is generated between a motor real instantaneous reactive power and an estimated instantaneous reactive power. The advantage of such a real reactive power reference model is independence of the motor parameter variation. The estimation rotor resistance values are applied to the direct vector control system with a flux observer. Finally, the simulations and experiment are presented to validate the rotor resistance estimation algorithm of induction motor.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.4
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• pp.30-37
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• 1999

This study suggested the Fuzzy Lyapunov dimension. The Fuzzy Lyapunov dimension is to evaluate the quantitative variation of the attractor. In this paper the speaker recognition is evaluated by the Fuzzy Lyapunov dimension. It has been proved that the suggested Fuzzy Lyapunov dimension is superior in the discrimination characteristics between standard reference pattern attractors, and in reference to the test pattern attractor, it has been verified that it is the speaker recognition parameter which absorbs the pattern variation. In order to evaluate the Fuzzy Lyapunov dimension as speaker recognition parameter, the mistaken recognition according to discrimination error in each of speaker and standard reference pattern was estimated, and the validity of the speaker recognition parameter was experimental. As the result of the speaker recognition experiment, 97.0[%] of recognition ratio was obtained, and it was confirmed that the Fuzzy Lyapunov dimension was fit for the speaker recognition parameter.

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.206.1-206
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• 2002

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.5
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• pp.72-78
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• 2006

The paper proposes reference model error feedback control scheme for motion control system with hard non-linear components as like saturation and dead-zone in plant input part. Additionally, the plant has the system uncertainty effected by plant model parameter deviation and disturbance. The control algorithm uses the reference model to apply additional feedback loop with the error between reference model output and actual output effected by disturbance and non-linear components. And the stability evaluation based on Popov stability and controller design method are formulated to be performed. The effectiveness of the proposed scheme is examined by simulations. The results are proven by reasonable performances following reference model responses with good disturbance rejection performance without over-tuning of controller.