• 한국추진공학회지
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• 제17권3호
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• pp.30-36
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• 2013

추진장약의 저장 기간에 따른 안정제 함량의 저하에 관하여 가속수명시험 자료를 활용한 수명 예측 기법을 제시하였다. 결정론적 가속수명시험 및 저장분석 시험자료를 단순회귀분석으로 계산한 수명 예측값은 상태 분포와 수명 분포를 표현할 수 없다. 기존의 연구에서 감마분포를 이용하여 저장분석 시험자료에 대한 상태 분포 및 수명 분포를 보여주고 기대 수명을 계산하는 방법이 제시되었으나, 양산 초기 실제 자료를 수집하는 것이 불가능한 한계를 가지고 있다. 본 연구에서 제시된 예측 방법에 의한 기대 수명은 기존의 연구와 유사한 값을 보이며 상태 분포와 수명 분포를 설명할 수 있고, 유도무기 추진기관의 추진제 또는 부품류의 노화와 관련한 수명 주기 관리에도 활용할 수 있다.

• 한국군사과학기술학회지
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• 제16권5호
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• pp.639-645
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• 2013

The aim of the study is to investigate the method to estimate a storage life of propelling charge on the decrease of muzzle velocity by stochastic gamma process model. It is required to establish criterion for state failure to estimate the storage life and it is defined in this paper as a muzzle velocity difference between reference value and maximum allowable standard deviation multiplied by 6. The relationship between storage time and muzzle velocity is investigated by nonlinear regression analysis. The stochastic gamma process model is used to estimated the state distribution and the life distribution for storage time for 155mm propelling charge KM4A2 because the regression analysis is a deterministic method and it can't describe the distribution of life for storage time.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2011년도 춘계학술발표대회 논문집
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• pp.41-48
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• 2011

In order to assess the reliability of the Tire Pressure Sensor for automobiles, accelerated life test model and procedure are developed. By using this method, failure mechanism and life distribution are analyzed. The main results are as follows; i) the main failure mechanism is degradation failure that is, PCB destruction and battery Discharge by high temperature. ii) the life distribution of the Tire Pressure Sensor fitted well to Weibull life distribution and the accelerated life model of that is fitted well to Arrhenius model. iii) at the result of the life distribution, accelerated life test method is developed

• 대한기계학회논문집A
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• 제33권8호
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• pp.707-719
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• 2009

The variables relating to the fatigue behavior have uncertainty and are random. The fatigue crack propagation is, thus, stochastic in nature. In this study, fatigue experiments are performed on the specimen of the magnesium alloy AZ31. The data of the fatigue life are scattered even in the same experimental condition. It is necessary to determine the probability distribution of the fatigue crack propagation life for the reliability analysis as well as the design and maintenance of structural components. Therefore the statistics and the probability distribution for the fatigue crack propagation life are investigated and the best fit probability distribution of that is proposed in this paper.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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• pp.391-394
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• 2009

In this paper, achieved rise temperature distribution about degradation phenomenon of 2 MVA distribution mold transformer using finite element method (FEM). Usually, life of transformer is depended on temperature distribution of specification region than thermal special quality of transformer interior. Specially, life of transformer by decline of dielectric strength decreases rapidly in case rise by strangeness transformer interior hot spot temperature value permits. Because calculating high-voltage winding and low-voltage winding of mold transformer and Joule's loss of core for improvement these life, forecasted heat source, and high-voltage winding and low-voltage winding of mold transformer and rise temperature distribution of core for supply of electric power and temperature distribution of highest point on the basis of the result Also, calculated temperature rise limit of mold transformer and permission maximum temperature using analysis by electron miracle heat source alculate and forecasted rise temperature distribution by heat source of thermal analysis with calculated result.

• Journal of Information Technology Applications and Management
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• 제28권4호
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• pp.13-20
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• 2021

In this paper, I was applied the life distribution following linear failure rate distribution, Lindley distribution and Burr-Hatke exponential distribution extensively used in the arena of software reliability and were associated the reliability possessions of the software using the nonhomogeneous Poisson process with finite failure. Furthermore, the average value functions of the life distribution are non-increasing form. Case of the linear failure rate distribution (exponential distribution) than other models, the smaller the estimated value estimation error in comparison with the true value. In terms of accuracy, since Burr-Hatke exponential distribution and exponential distribution model in the linear failure rate distribution have small mean square error values, Burr-Hatke exponential distribution and exponential distribution models were stared as the well-organized model. Also, the linear failure rate distribution (exponential distribution) and Burr-Hatke exponential distribution model, which can be viewed as an effectual model in terms of goodness-of-fit because the larger assessed value of the coefficient of determination than other models. Through this study, software workers can use the design of mean square error, mean value function as a elementary recommendation for discovering software failures.

• Structural Engineering and Mechanics
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• 제37권4호
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• pp.427-442
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• 2011

In fatigue life design of mechanical components, uncertainties arising from materials and manufacturing processes should be taken into account for ensuring reliability. A common practice is to apply a safety factor in conjunction with a physics model for evaluating the lifecycle, which most likely relies on the designer's experience. Due to conservative design, predictions are often in disagreement with field observations, which makes it difficult to schedule maintenance. In this paper, the Bayesian technique, which incorporates the field failure data into prior knowledge, is used to obtain a more dependable prediction of fatigue life. The effects of prior knowledge, noise in data, and bias in measurements on the distribution of fatigue life are discussed in detail. By assuming a distribution type of fatigue life, its parameters are identified first, followed by estimating the distribution of fatigue life, which represents the degree of belief of the fatigue life conditional to the observed data. As more data are provided, the values will be updated to reduce the credible interval. The results can be used in various needs such as a risk analysis, reliability based design optimization, maintenance scheduling, or validation of reliability analysis codes. In order to obtain the posterior distribution, the Markov Chain Monte Carlo technique is employed, which is a modern statistical computational method which effectively draws the samples of the given distribution. Field data of turbine components are exploited to illustrate our approach, which counts as a regular inspection of the number of failed blades in a turbine disk.

• Journal of the Korean Data and Information Science Society
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• 제15권4호
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• pp.935-943
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• 2004

Most of the accelerated life tests deal with tests that use only one accelerating variable and no other explanatory variables. Frequently, however, there is a test to use more than one accelerating or other experimental variables, such as, for examples, a test of capacitors at higher than usual conditions of temperature and voltage, a test of circuit boards at higher than usual conditions of temperature, humidity and voltage. A accelerated life test is extended to M-level stress accelerated life test with k-stress variables. The optimal design for Weibull distribution is studied with k-stress variables.

• 한국산업융합학회 논문집
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• 제10권3호
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• pp.143-147
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• 2007

In recents years, the statistical properties has become an important quantity for reliability based design of a component. The effects of the materials and test conditions for parameter estimation in residual strength degradation model are studied in carbon/epoxy laminate. It is shown that the correlation between the experimental results and the theoretical prediction on the fatigue life distribution using the life distribution convergence method is very reasonable.

• 산업경영시스템학회지
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• 제24권68호
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• pp.1-7
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• 2001

A probabilistic model for fatigue life of a structural component is derived when the component is in a variable-amplitude loading environment. The physical mechanism which governs fatigue failure is used to model the fatigue life. Especially, the judgement of rotational symmetry in the-stress-intensity-factors results in the probability distribution for fatigue life. The probability distribution is related to the familiar truncated Gaussian distribution, which has a single parameter with a direct physical meaning.