• 한국자동차공학회논문집
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• 제7권5호
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• pp.213-220
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• 1999

The life data analysis of the system and component are useful to describe the result of reliability test in product life to satisfy customer's growing need and to change test specifications or design criteria by life data analysis. And vehicle durability tesr occurred market environment. In this study, a statistical analysis for the wear life of brake pad linings helped perform correlation procedure between vehicle durability test and market. B-life values of the brake pad wear life data from both vehicle durability test and marker usage were compared to determine acceleration of the test by the Weibull, normal and log-normal distribution. The acceleration coefficient of the vehicle durability test can access to evaluate design criteria of product and test specification.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.160-165
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• 2004

At this research, we examined probability of light bulb's life span value and prediction on purpose to inquire out the span of repeat velocity as fracture probability by executing the fatigue test, which is considered property of Tungsten filament's thermal fatigue used as an automobile bulb. As a result we can confirm what the most suitable solution is weibull distribution and log normal distribution. Tungsten filament's span gets longer as the fatigue repeat velocity gets shorter And, repeat span is about 15%~40% shorter than sequence life span.

• 대한산업공학회지
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• 제12권1호
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• pp.139-146
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• 1986

This study is concerned with the development of statistical life test plans for the mean lifetime of an item whose underlying lifetime distribution is a two parameter Weibull, which is perhaps the most widely used lifetime model. For this purpose, I used the likelihood ratio test method, and I verified the developed test plans and determined the sampling size and censoring number by computer similation.

• 한국세라믹학회지
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• 제26권1호
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• pp.116-122
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• 1989

MOR test and concentric ring test were performed to evaluate the failure probability of sin/hip Si3N4 under uniaxial and biaxial stress state, respectively. Their failure probabilities were analized with KARA program based on Weibull PIA model and Batdorf model with 5 criteria, and they were compared with experiments. PIA model is in best accordance with experiments in higher fracture strength regions, especially for Pf 0.3. But in lower fracture strength region, none of the models predicts the failure probabilities appropriately.

• Ocean Systems Engineering
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• 제4권4호
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• pp.293-308
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• 2014

Unlike the traditional displacement type vessels, the high speed planing crafts are supported by the lift forces which are highly non-linear. This non-linear phenomenon causes their motions in an irregular seaway to be non-Gaussian. In general, it may not be possible to express the probability distribution of such processes by an analytical formula. Also the process might not be stationary or ergodic in which case the statistical behavior of the motion to be constantly changing with time. Therefore the extreme values of such a process can no longer be calculated using the analytical formulae applicable to Gaussian processes. Since closed form analytical solutions do not exist, recourse is taken to fitting a distribution to the data and estimating the statistical properties of the process from this fitted probability distribution. The peaks over threshold analysis and fitting of the Generalized Pareto Distribution are explored in this paper as an alternative to Weibull, Generalized Gamma and Rayleigh distributions in predicting the short term extreme value of a random process.

• 대한토목학회논문집
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• 제33권5호
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• pp.1731-1740
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• 2013

교량의 내구성과 설계수명 평가에 있어 대형화물차와 같은 중차량의 총중량 크기와 분포 특성은 큰 영향을 미치며, 총중량의 특성은 WIM 시스템에서의 측정 데이터를 활용하여 파악하고 있다. 고속도로상에 설치된 고속 WIM 시스템을 통해 측정된 중차량의 분포를 분석한 결과, 대부분의 중차량은 7종, 10종, 12종 화물차에서 발생하였다. 이들 화물차의 전체적인 총중량 분포와 상위 총중량 분포에 대한 확률분포 모델을 추정하였다. 전체적인 총중량 분포는 정규확률 분포에 근접하는 것으로 분석되었으며, 상위 10% 데이터는 극치분포의 하나인 Weibull 3 확률분포에 가장 높은 적합도를 갖는 것으로 나타났다.

• 대한기계학회논문집A
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• 제23권7호
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• pp.1139-1146
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• 1999

Reliability analysis of structures based on fracture mechanics requires knowledge on statistical characteristics of the parameter C and m in the fatigue crack growth law, $da/dN=C({\Delta}K)^m$. The purpose of the present study is to investigate if it is possible to predict fatigue crack growth rate by only the fluctuation of the parameter C. In this study, Paris-Erdogan law is adopted, where the author treat the parameter C as random and m as constant. The fluctuation of crack growth rate is assumed only due to the parameter C. The growth resistance coefficient of material to fatigue crack growth (Z=1/C) was treated as a spatial stochastic process, which varies randomly on the crack path. The theoretical crack growth rates at various stress intensity factor range are discussed. Constant ${\Delta}K$ fatigue crack growth tests were performed on the structural steel, SM45C. The experimental data were analyzed to determine the autocorrelation function and Weibull distributions of the fatigue crack growth resistance. And also, the effect of the parameter m of Paris' law due to variation of fatigue crack growth resistance was discussed.

• 한국안전학회지
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• 제32권5호
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• pp.115-121
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• 2017

This paper is to introduce the main modeling assumptions and data structures associated with right-censored data to describe the successful methodological ideas for analyzing such a field-failure-data when components operating in different environments. The Kaplan - Meier method is the most popular method used for survival analysis. Together with the log-rank test, it may provide us with an opportunity to estimate survival probabilities and to compare survival between groups. An important advantage of the Kaplan - Meier curve is that the method can take into account some types of censored data, particularly right-censoring. The above non-parametric method was used to verify the equality of parts life used in different environments. After that, we performed the life distribution analysis using the parametric method. We simulated data from three distributions: exponential, normal, and Weibull. This allowed us to compare the results of the estimates to the known true values and to quantify the reliability indices. Here we used the Akaike information criterion to find a suitable life time distribution. If the Akaike information criterion is the smallest, the best model of failure data is presented. In this paper, no-nparametrics and parametrics methods are analyzed using R program which is a popular statistical program.

• 한국산업융합학회 논문집
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• 제22권6호
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• pp.681-688
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• 2019

SM45C steel, which is widely used for mechanical structure, was carburized at 870℃ for 4 hours and tempered at 300℃ and 400℃ for 1, 3 and 6 hours. The tempered materials were evaluated for tensile test, hardness test and impact test. In particular, the hardness and the absorption energy were evaluate the reliability by the Weibull statistical analysis. 300℃-1h specimen is considered to be the best heat treatment condition in the tensile stress and the observation of fracture surface. 300℃-1h specimen showed larger shape and scale parameter than the other specimens, and Rockwell hardness variance was small and showed the best characteristics. 400℃-3h specimen showed larger shape and scale parameter than the other specimens, the dispersion of impact absorption energy is small, and showed excellent characteristics.

• Structural Engineering and Mechanics
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• 제69권3호
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• pp.347-359
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• 2019

This paper aims to evaluate the behavior of Dorim-Goh bridge in Seoul, Korea, under static and dynamic loads effects by ambient trucks. The prestressed concrete (PSC) girders and reinforcement concrete (RC) slab of the bridge are evaluated and assessed. A short period monitoring system is designed which comprises displacement, strain and accelerometer sensors to measure the bridge performance under static and dynamic trucks loads. The statistical analysis is used to assess the static behavior of the bridge and the wavelet analysis and probabilistic using Weibull distribution are used to evaluate the frequency and reliability of the dynamic behavior of the bridge. The results show that the bridge is safe under static and dynamic loading cases. In the static evaluation, the measured neutral axis position of the girders is deviated within 5% from its theoretical position. The dynamic amplification factor of the bridge girder and slab are lower than the design value of that factor. The Weibull shape parameters are decreased, it which means that the bridge performance decreases under dynamic loads effect. The bridge girder and slab's frequencies are higher than the design values and constant under different truck speeds.