• International Journal of Reliability and Applications
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• 제2권3호
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• pp.189-197
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• 2001

The estimation of mean lifetimes in presence of interval censoring with mixed replacement procedure is examined when the distributions of lifetimes are exponential. It is assumed that, due to physical restrictions and/or economic constraints, the number of failures is investigated only at several inspection times during the lifetime test; thus there is interval censoring. The maximum likelihood estimator is found in an implicit form. The Cramor-Rao lower bound, which is the asymptotic variance of the estimator, is derived. The estimation of mean lifetimes for competing failures model has been expanded.

• Communications for Statistical Applications and Methods
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• 제22권6호
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• pp.625-637
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• 2015

We develop a Bayesian clustering procedure based on a Dirichlet process prior with cluster specific random effects. Gibbs sampling of a normal mixture of linear mixed regressions with a Dirichlet process was implemented to calculate posterior probabilities when the number of clusters was unknown. Our approach (unlike its counterparts) provides simultaneous partitioning and parameter estimation with the computation of the classification probabilities. A Monte Carlo study of curve estimation results showed that the model was useful for function estimation. We find that the proposed Dirichlet process mixture model with cluster specific random effects detects clusters sensitively by combining vague edges into different clusters. Examples are given to show how these models perform on real data.

• 대한기계학회논문집A
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• 제22권3호
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• pp.569-578
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• 1998

The mode I and II stress intensity factors have been calculated theoretically for the cracked plate reinforced with a plate by symmetric spot welding under remote mixed mode loading. This is the extension of authors' previous work for the reinforced cracked plate under remote normal stress. Regardless of loading types, the reinforcement effect gets better as one joining spot is closer to the crack tip and the others are closer to the crack surface, and optimum number of the joining spots can be existed. For the present model, the remote loading parallel to crack surface produces the mode I stress intensity factor.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.213-217
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• 2005

In this study the water including sediment is assumed that the density is different from fresh water. And the phenomenon inhaled by low pressure around the pipe is numerically simulated in two dimension. The simulation is done using finite difference method in rectangular staggered mesh system and Navier-Stokes equations and continuty equation are employed as governing equations. The method of Irregular leg lengths and stars are adopted to satisfy boundary condition of body boundary. Marker-Density method is used to calculate the density of mixed flow. Also SGS turbulence model is applied to consider vortex smaller then grid at high Renolds number. This study is to analyze inhalation phenomenon of mixed flow with sediment and to verify the numerical method for mixed flow. To verify the numerical results are compared with experimental results

• 대한산업공학회지
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• 제24권2호
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• pp.251-260
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• 1998

This paper deals with a simulated annealing neural network model for determining sequences of models inputted into a mixed model assembly line. We first present a energy function fitting to our problem, next determine the value of the parameters of the energy function using convergence ratio and the number of searched feasible solution. Finally we compare our model NMS with the modified Thomopoulos model. The result of the comparison shows that NMS and Thomopoulos offer a similar output in the problems having good smoothness.

• 산업공학
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• 제17권3호
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• pp.282-293
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• 2004

Line Balancing is the problem to assign tasks to stations while satisfying some managerial viewpoints. Most researches about the Mixed-Model Line Balancing problems are focused on the minimizing the total processing time or the number of workstations. Independently, some research reports consider the balance issues of the physical workloads on the assembly line. In this paper, we are presenting a new mathematical model to accomplish the line balance considering both the processing time and the workloads at the same time. To this, end, we propose an zero-one integer program problem, and we use the Chebyshev Goal Programming approach as the solution method. Some computational test runs are performed to compare the pay-offs between the processing time and the workloads. And, the test results show us that the reliable balanced work schedules can be obtained through the proposed model.

• 산업공학
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• 제24권2호
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• pp.151-155
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• 2011

In this study, we propose a signomial classification method with ₀-regularization (₀-)which seeks a sparse signomial function by solving a mixed-integer program to minimize the weighted sum of the ₀-norm of the coefficient vector of the resulting function and the $L_1$-norm of loss caused by the function. $SC_0$ gives an explicit description of the resulting function with a small number of terms in the original input space, which can be used for prediction purposes as well as interpretation purposes. We present a practical implementation of $SC_0$ based on the mixed-integer programming and the column generation procedure previously proposed for the signomial classification method with $SL_1$-regularization. Computational study shows that $SC_0$ gives competitive performance compared to other widely used learning methods for classification.

• 대한산업공학회지
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• 제30권4호
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• pp.317-327
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• 2004

In mixed-model production systems, various models of products are produced alternately on the same production line. When the total number of models or the total production quantity is large, it takes a long time to determine the production sequence of the products. In this paper, we will show that in case of product rate variation problem (PRV) problem with nonidentical symmetric convex discrepancy function, an optimum sequence can be obtained by repeating an optimum sequence in a reduced subproblem.

• Communications for Statistical Applications and Methods
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• 제6권2호
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• pp.443-456
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• 1999

The estimation of mean lifetimes in presence of interval censoring with mixed replacement procedure are examined when the distribution s of lifetimes are exponential. it is assumed that due to physical restrictions and/or economic constraints the number of failures is investigated only at several inspection times during the lifetime test; thus there is interval censoring. Comparisons of mixed replacement designs are made with those with and without replacement The maximum likelihood estimator is found in an implicit form. The Cramer-Rao lower bound which is the asymptotic variance of the estimator is derived. The test conditions for minimizing the Cramer-Rao lower bound and minimizing the test costs within a desired width of the Cramer-Rao bound have been studied.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.473-476
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• 2000

Recently, many studies focus on mixed-mode fatigue-fracture characteristics of characteristics of materials. In order to reveal crack initiation and propagation mechanisms in combined -mode fatigue. This paper investigates the initiation and propagation behavior of the fatigue crack of the STS304 specimens under mixed mode loading conditions. moreover crack arrest and branch phenomena were analyzed with respect to the change do the angle of inclined loading. The relationship between the angle of inclined loading and the angle of branched crack was studied. A greate number of cycles are necessary to initiate a new crack from the initial crack. The direction of the new crack propagation is determined by MTS theory.