• Journal of Environmental Science International
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• v.13 no.12
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• pp.1041-1048
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• 2004

In this study the results of optimal water supply analysis by operating constraints of reservoirs during drought period are as follows. During drought period, water supply reliability is possible about $97\~61{\%}$ by CASE 1-CASE 5. Water supply reliability is possible about $97.3{\%}$ in case of the Andong dam and $87.7{\%}$ in case of the Imha dam by CASE 3. Also, under the constraints of CASE 4, water supply reliability is possible about $87.5{\%}$ in case of the Andong dam and $73.3{\%}$ in case of the Imha dam. The reason what low of available water supply ratio is decreased inflow of Imha dam. When compare standard deviation of average storage with standard deviation of storage, stable storage can be secured during successive drought period. And it also can minimize shortage of water during drought. therefore, it is impossible that reservoir supply sufficient water but change of operating condition is better than pervious on that followed by full reservoir level. It is need that the study for optimal water supply during drought period has to be continued.

• The Transactions of the Korea Information Processing Society
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• v.6 no.12
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• pp.3662-3674
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• 1999

This paper addresses some design issues for establishing the optimal number of spare units in array systems manufactured using fault-tolerant multichip modules(MCM's) for massively parallel computing(MPC). We propose a new quantitative approach to an optimal cost-effective MCM system design under yield and reliability constraints. In the proposed approach, we analyze the effect of residual redundancy on operational reliability of fault-tolerant MCM's. In particular, the issues of imperfect support circuitry, chip assembly yield and array topology are investigated. Extensive parametric results for the analysis are provided to show that our scheme can be applied to design ways using MCM's for MPC applications more efficiently, subject to yield and reliability constraints.

• Journal of Korean Society for Quality Management
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• v.32 no.4
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• pp.125-139
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• 2004

Generally, parallel redundancy is used to improve reliability in many systems. However, redundancy increases system cost, weight, volume, power, etc. Due to limited availability of these resources, the system designer has to maximize reliability subject to various constraints or minimize resources while satisfying the minimum requirement of system reliability. This paper presents GAs (Genetic Algorithms) to solve redundancy allocation in series-parallel systems. To apply the GAs to this problem, we propose a genetic representation, the method for initial population construction, evaluation and genetic operators. Especially, to improve the performance of GAs, we develop heuristic operators (heuristic crossover, heuristic mutation) using the reliability-resource information of the chromosome. Experiments are carried out to evaluate the performance of the proposed algorithm. The performance comparison between the proposed algorithm and a pervious method shows that our approach is more efficient.

• International Journal of Reliability and Applications
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• v.12 no.2
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• pp.79-94
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• 2011

Redundancy-reliability allocation problems in multi-stage series-parallel systems are addressed in this study. Fuzzy programming techniques are proposed for finding satisfactory solutions. First, a multi-objective programming model is formulated for simultaneously maximizing system reliability and minimizing system total cost. Due to the nature of uncertainty in the problem, the fuzzy set theory and technique are used to convert the deterministic multi-objective programming model into a fuzzy nonlinear programming problem. A heuristic method is developed to get satisfactory solutions for the fuzzy nonlinear programming problem. A Pareto optimal solution is found with maximal degree of satisfaction from the interception area of fuzzy sets. A case study that is related to the electronic control unit installed on aircraft engine over-speed protection system is used to implement the developed approach. Results suggest that the developed fuzzy multi-objective programming model can effectively resolve the fuzzy and uncertain problem when design goals and constraints are not clearly confirmed at the initial conceptual design phase.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.4
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• pp.334-345
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• 1997

Reliability-based design approaches are needed for cylindrical shell structure whose design and operational experiences are few and which are subjected to external loads of random loads. In designing new type of structure, it is very difficult to evaluate the safety factors due to lack of previous design data and operational experience. To solve the above mentioned problem, much attention is being focussed on rational reliability based design approaches. This paper deals with weight-optional reliability-based design of cylindrical shell structure subjected to structural reliability constraints taking into account of the effect of local buckling and interactive behavior between local and global buckling. Present mentioned is compared with the exiting optional design method based only on safety factors. Numerical simulation reveals that the present method leads to lighter structure (4% reduction in weight compared to the existing optimal design) with the same reliability index. For larger structures with more number of structural members and possible failure modes, the present W0RBD procedure will be an efficient tool in designing cost-effective rationalized economic design.

• Journal of Electrical Engineering and Technology
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• v.8 no.2
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• pp.331-338
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• 2013

A new reliability calculation method is proposed based on design sensitivity analysis by the finite element method for nonlinear performance constraints in the optimal design of electromagnetic devices. In the proposed method, the reliability of a given design is calculated by using the Monte Carlo simulation (MCS) method after approximating a constraint function to a linear one in the confidence interval with the help of its sensitivity information. The validity and numerical efficiency of the proposed sensitivity-assisted MCS method are investigated by comparing its numerical results with those obtained by using the conventional MCS method and the first-order reliability method for analytic functions and the TEAM Workshop Problem 22.

• IE interfaces
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• v.25 no.2
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• pp.153-162
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• 2012

The reliability is defined as a probability that a system will operate properly for a specified period of time under the design operating conditions without failure and it has been considered as one of the major design parameters in the field of industries. Reliability-Redundancy Optimization Problem(RROP) involves selec tion of components with multiple choices and redundancy levels for maximizing system reliability with constraints such as cost, weight, etc. However, in practice both active and cold standby redundancies may be used within a particular system design. Therefore, a redundancy strategy(active, cold standby) for each subsystem in order to maximize system reliability is considered in this study. Due to the nature of RROP, i.e. NP-hard problem, A Parallel Particle Swarm Optimization(PPSO) algorithm is proposed to solve the mathematical programming model and it gives consistently better quality solutions than existing studies for benchmark problems.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.704-710
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• 2018

For the optimal design of electromagnetic device involving uncertainties in design variables, this paper proposes a new reliability-based optimal design algorithm for multiple constraints problems. Through optimizing the nominal objective function and maximizing the minimum reliability, a set of global optimal reliable solutions representing different reliability levels are obtained by the multi-objective particle swarm optimization algorithm. Applying the sensitivity-assisted Monte Carlo simulation method, the numerical efficiency of optimization procedure is guaranteed. The proposed reliability-based algorithm supplying multi-reliable solutions is investigated through applications to analytic examples and the optimal design of two electromagnetic problems.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.4
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• pp.244-258
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• 2019

The reliability of power electronic systems becomes increasingly important, as power electronic systems have gradually gained an essential status in a wide range of industrial applications. Accordingly, recent research has made an effort to improve the reliability of power electronic systems to comply with stringent constraints on safety, cost, and availability. The condition monitoring of power electronic components is one of the main topics in the research area of the reliability of power electronic systems. In this paper, condition-monitoring methods of reliability-critical components in power electronic systems are discussed to provide the current state of knowledge by organizing and evaluating current representative literature.

• Korean Journal of Construction Engineering and Management
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• v.10 no.1
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• pp.36-44
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• 2009

The sum of each work duration are entire period in construction project. Each work occurs to be late, the total period of construction project will delays. Therefore, the total period of construction project will not be delayed if probability of work progress makes higher. Finding each work constraints performs constraints analysis in process of construction for checking probability of work progress. Grasp work constraints through the constraints analysis and removes. This research will show preventing delay of construction project, through work condition analysis process.