• Structural Engineering and Mechanics
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• v.74 no.1
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• pp.55-67
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• 2020

The common practice to predict the characteristic structural load effects (LEs) in long reference periods is to employ the extreme value theory (EVT) for building limit distributions. However, most applications ignore that LEs are driven by multiple loading events and thus do not have the identical distribution, a prerequisite for EVT. In this study, we propose the composite extreme value modeling approach using clustering to (a) cluster initial blended samples into finite identical distributed subsamples using the finite mixture model, expectation-maximization algorithm, and the Akaike information criterion; (b) combine limit distributions of subsamples into a composite prediction equation using the generalized Pareto distribution based on a joint threshold. The proposed approach was validated both through numerical examples with known solutions and engineering applications of bridge traffic LEs on a long-span bridge. The results indicate that a joint threshold largely benefits the composite extreme value modeling, many appropriate tail approaching models can be used, and the equation form is simply the sum of the weighted models. In numerical examples, the proposed approach using clustering generated accurate extrema prediction of any reference period compared with the known solutions, whereas the common practice of employing EVT without clustering on the mixture data showed large deviations. Real-world bridge traffic LEs are driven by multi-events and present multipeak distributions, and the proposed approach is more capable of capturing the tendency of tailed LEs than the conventional approach. The proposed approach is expected to have wide applications to general problems such as samples that are driven by multiple events and that do not have the identical distribution.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.3
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• pp.367-372
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• 2008

In this paper we proposed a model of a fault diagnosis expert system with high reliability to compare identical well-functioning motors. The purpose of the survey was to determine if any differences exit among these identical motors and to identify exactly what these differences were, if in fact they were found. Using measured data for many identical brushless dc motors, this study attempted to find out whether normal and fault can be classified by each other. Measured data was analyzed using the State Transition Model (STM). Based on a proposed STM method, the effect of a different normal state is minimized and the detection of fault is improved in identical motor system. Experimental results are presented to prove that STM method could be a useful tool for diagnosing the condition of identical BLDE motors.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.213-216
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• 2005

The time synchronization method for Multi-band UWB systems is proposed. We analyze the performance in symbol synchronization using a training symbol with two identical halves. The two halves of the training symbol are made identical by transmitting a modulated sequence on the even frequencies, while zeros are used on the odd frequencies.

• East Asian Economic Review
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• v.20 no.2
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• pp.191-228
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• 2016

This paper analyzes the role of absorptive capacity in R&D spillovers through strategic R&D investments in a game-theoretic framework. In the model, a firm's effective R&D is composed of idiosyncratic R&D, which produces its own innovations, and identical R&D, which improves absorptive capacity. The model shows that in the presence of absorptive capacity firms have a tendency to underinvest (overinvest) in idiosyncratic (identical) R&D relative to the social optimum. As the spillover becomes larger, firms decrease their own R&D while they become more inclined towards strategic exploitation of rivals' efforts. Since the former effect overpowers the latter, the total amount of R&D decreases as the spillover increases. This is socially undesirable, providing a potential justification for a governmental subsidy for idiosyncratic R&D and a tax on identical R&D. The findings may have important implications for newly industrialized or emerging countries that consider a redirection of national R&D policy and intellectual property rights (IPR) regime.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.10
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• pp.1144-1150
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• 2009

This paper investigates the feasibility of the Bayesian discrete time approximation method to estimate the parameters of Weibull distributions of failures for two non-identical components connected in series system. A Bayesian model based on the discrete time approximation method is formulated to infer the Weibull parameters of two non-identical components with the failure data of the virtual tests. The study of this paper comes to a conclusion that the method is feasible only for some special cases under the given constraints on the concerned parameters.

• Journal of the Korean Operations Research and Management Science Society
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• v.39 no.3
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• pp.83-91
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• 2014

We consider the problem of scheduling identical jobs with sequence-independent setup times on parallel machines. The objective is to minimize total completion times. We present the pseudopolynomial-time algorithm for the case with a fixed number of machines and an efficient approximation algorithm for our problem with identical setup times, which is known to be NP-hard even for the two-machine case.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.582-584
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• 1999

Generator has synchronized with power Network after build-up output voltage. In order to prevent a current surge when synchronizing, the conditions such as identical no-load voltages identical no-load frequencies and identical phase positions must be met between generator voltage and network voltage. Hydro-Pump generators or Gas-turbine generators, Co-generation Generators that serve peak load of network are synchronized many times. So, Automatic Synchronizing Circuits are very important service. This report apply Diagnosis methods the Automatic Synchronizing Circuits(Device) by developing simulator.

• IE interfaces
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• v.18 no.3
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• pp.297-307
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• 2005

PCB assembly is a complicated and difficult process to optimize due to the necessity of simultaneous consideration of component’s rack assignment and board mounting sequencing. An efficient PCB assembly method is developed by using neighboring positioned identical components information as well as quantity and size of the components. It is found that same type of components are located closely each other by checking real PCBs and interviewing with PCB designers in practice. Better performance of the developed procedure is obtained along with more number of total components and more number of neighboring positioned identical components cases. Simulation models are developed using Visual C++ for performance evaluation purposes of the suggested heuristic.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.3
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• pp.305-312
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• 2014

This research deals with a problem that minimizes makespan in a non-identical parallel machine system with sequence and machine dependent setup times and machine dependent processing times. We first present a new mixed integer programming formulation for the problem, and using this formulation, one can easily find optimal solutions for small problems. However, since the problem is NP-hard and the size of a real problem is large, we propose four heuristic algorithms including genetic algorithm based heuristics to solve the practical big-size problems in a reasonable computational time. To assess the performance of the algorithms, we conduct a computational experiment, from which we found the heuristic algorithms show different performances as the problem characteristics are changed and the simple heuristics show better performances than genetic algorithm based heuristics for the case when the numbers of jobs and/or machines are large.

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.2
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• pp.33-46
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• 2000

The problem of scheduling n independent jobs on serial stages with identical parallel machines at each stage is considered. Each job lot is allocated evenly to all machines at each stage for processing and moved in transfer batches between states., This scheduling strategy is called an identical production pattern. The objective is to find a permutation schedule that minimizes makespan. A branch and bound algorithm is suggested to find an optimal permutation schedule for a transformed problem A number examples is presented to illustrate the branch and bound algorithm, Computational results for 640 problems generated randomly show that within a resonable time the suggested algorithm can be used for transfer batch scheduling in a flexible flowshop.