• Journal of the Korean Data and Information Science Society
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• 제21권5호
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• pp.935-944
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• 2010

In this paper, we develop the noninformative priors for the reliability in a stress-strength model where a strength X and a stress Y have independent exponential distributions with different scale parameters and a common location parameter. We derive the reference priors and prove the propriety of joint posterior distribution under the general prior including the reference priors. Through the simulation study, we show that the proposed reference priors match the target coverage probabilities in a frequentist sense.

• 소성∙가공
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• 제10권1호
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• pp.53-58
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• 2001

Set-up reference values, used in determining the optimum downcoiling tension, we experimentally verified in this study. During the actual downcoiling, the strip suffers both tension and bending force through the rotation of mandrel. Therefore, simulative test which can measure both tension and bending resistance of strip was performed to estimate set-up reference value for strip tension during downcoiling operations. The values obtained from the simulative test were correlated with the yield stress which has conventionally been used as reference values for downcoiling tension. The correlative analysis showed that the yield stress of strip can be a good reference value for downcoiling tension. Furthermore, the bending load also shows strong correlation with simulated values due to the close relationship between yield stress and bending load.

• Smart Structures and Systems
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• 제17권5호
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• pp.725-742
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• 2016

This paper is focused on stiffness ratio effect and a new method to specify the best pattern of piezoelectric patches placement around a hole in a plate under tension to reduce the stress concentration factor. To investigate the stiffness ratio effect, some different values greater and less than unity are considered. Then a python code is developed by using particle swarm optimization algorithm to specify the best locations of piezoelectric actuators around the hole for each stiffness ratio. The results show that, there is a line called "reference line" for each plate with a hole under tension, which can guide the location of actuator patches in plate to have the maximum stress concentration reduction. The reference line also specifies that actuators should be located horizontally or vertically. This reference line is located at an angle of about 65 degrees from the stress line in plate. Finally two experimental tests for two different locations of the patches with various voltages are carried out for validation of the results.

• Journal of the Korean Statistical Society
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• 제35권3호
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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.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.80-86
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• 2001

An engineering estimation equation for the crack opening displacement (COD) is proposed for a complex cracked pipe, based on the reference stress approach. To define the reference stress, a simple plastic limit load analysis for the complex cracked pipe subjected to combined bending and tension is performed considering the crack closure effect in the compressive-stressed region. Comparison with ten published test data and the results from existing method shows that the present method not only reduces non-conservatism associated with the existing method, but also provides consistent and overall satisfactory results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.143-148
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• 2003

This paper provides two types of engineering J estimation equations for cylinders with finite internal axial surface cracks under internal pressure. The first type is the so-called GE/EPRI type J estimation equation based on Ramberg-Osgood materials. Based on detailed 3-D FE results the GE/EPRI-type J estimation equation along the crack front is proposed and validated for Ramberg-Osgood materials. For more general application, the developed GE/EPRI-type solutions are then re-formulated based on the reference stress concept. The proposed reference stress based J estimation equation has good agreement between the FE results and the proposed reference stress based J estimation provides confidence in the use of the proposed method for elastic-plastic fracture mechanics of pressurised piping

• 한국지반공학회지:지반
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• 제6권4호
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• pp.33-42
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• 1990

정적관입저항 또는 선단지지말뚝의 선단지지력을 해석함에 있어서는 유효수직응력이 기준음력으로 사용되어 왔다. 그러나 정적관입저항은 유효수직응력보다 원위치 유효수평응력에 관계된다는 것이 많은 실험연구결과로부터 보고 되었다. 이와같은 문제점을 규명하기 위하여 기 보고된 실험결과를 다시 분석하였으며 실험실에서의 관입시험이 실시되었다. 연구결과 정적관입저항은 유효수직 응력과 유효수평응력 모두에 영향을 받는 것으로 나타나고 있으며 해석시에는 평균주응력이 기준응력으로 사용되어야 함을 결론 지을 수 있었다.

• Structural Engineering and Mechanics
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• 제55권4호
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• pp.885-900
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• 2015

This paper introduces Romberg-Richardson's method as one of the numerical integration tools for computation of stress intensity factor in a pre-cracked specimen subjected to a complex stress field across the crack faces. Also, the computation of stress intensity factor for various stress fields using existing three methods: average stress over interval method, piecewise linear stress method, piecewise quadratic method are modified by using Richardson extrapolation method. The direct integration method is used as reference for constant and linear stress distribution across the crack faces while Gauss-Chebyshev method is used as reference for nonlinear distribution of stress across the crack faces in order to obtain the stress intensity factor. It is found that modified methods (average stress over intervals-Richardson method, piecewise linear stress-Richardson method, piecewise quadratic-Richardson method) yield more accurate results after a few numbers of iterations than those obtained using these methods in their original form. Romberg-Richardson's method is proven to be more efficient and accurate than Gauss-Chebyshev method for complex stress field.

• 대한음성학회지:말소리
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• 제67호
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• pp.1-16
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• 2008

Stress effects upon Korean vowels were investigated with reference to rhythm. We measured three acoustic correlates (Duration: VOT, Vowel Duration; F0; Intensity) of stress from the seven pairs of stressed vs. unstressed Korean vowels /i, ${\varepsilon}(e)$, a, o, u, i, e/. The results of the experiment revealed that stress gave only inconsistent and weak effects on duration, which supports that Korean is not a stress-timed language as far as strong stress effects on duration are still considered crucial in stress-timing. On the other hand, Korean stressed vowels were most characterized with higher F0 and next with stronger intensity. But speakers generally showed tactics to reversely use F0 and intensity in stressing an utterance rather than proportionately strengthening both of the two acoustic correlates of stress. There was found great inter-speaker variability especially in the variations of duration.

• Journal of the Korean Data and Information Science Society
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• 제22권1호
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• pp.115-123
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• 2011

In this paper, we develop the noninformative priors for stress-strength reliability from the Pareto distributions. We develop the matching priors and the reference priors. It turns out that the second order matching prior does not match the alternative coverage probabilities, and is not a highest posterior density matching or a cumelative distribution function matching priors. Also we reveal that the one-at-a-time reference prior and Jeffreys' prior are the second order matching prior. We show that the proposed reference prior matches the target coverage probabilities in a frequentist sense through simulation study, and an example is given.