• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1555-1558
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• 2008

In this paper, result of whole test, When the Transfer Distance is increasing, Strength of Backfilling Material of NATM Composite lining Tunnel due to increasing Gravity was increased, but that is higher the Air Flotation than increasing Strength. So, That was predicted a drop of Permeability. And Performing the placing Lightweight Foamed Mortar, we think that it's performance in drain material was lost. Therefore We conclude that Proper Transfer Distance that taking Permeability through minimizing of Air Flotation Loss and getting the Need Strength is 50m.

• 한국공작기계학회논문집
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• 제16권6호
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• pp.55-61
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• 2007

The hypoid gear has advantage for the high reduction ratio and compactness. But, geometry design and strength evaluation of the hypoid gear depend on the machine tool of specific production companies because the geometry design and strength evaluation of the hypoid gear are complex and difficult. This paper proposes the development of the design programs to satisfying the geometry and strength of a hypoid gear through optimization technique using the genetic algorithm. The genetic algorithm is designed to optimize a method for minimizing volume. The existing design of hypoid gear in the forklift truck axle is compared with the results of developed optimum design program.

• 산업경영시스템학회지
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• 제22권53호
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• pp.23-35
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• 1999

Since on-time delivery is becoming increasingly important in today's competitive markets, the development of effective scheduling methodologies to meet customer needs through on time delivery is of vital importance for the well-being of companies. The objective of this study is to develope a general heuristic algorithm for scheduling both the static and dynamic problems under certain on-time delivery criteria. For the problems with due-date related, we present insights for minimizing the number of tardy jobs and propose a heuristic scheduling algorithm. Experimental results show that the proposed algorithm performs significantly better than other dispatching rules within reasonable computation time, specially in the environment of strong competition for resources.

• 대한안전경영과학회지
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• 제9권2호
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• pp.123-134
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• 2007

This paper focuses on the in-house reliability assurance plan for the bulk materials of each company. The reliability assurance needs in essence a long time and high cost for testing the materials. In order to reduce the time and cost, accelerated life test is adopted. The bulk sampling technique was used for acceptance. Design parameters might be total sample size(segments and increments}, stress level and so on. We focus on deciding the sample size by minimizing the asymptotic variance of test statistics as well as satisfying the consumer's risk. In bulk sampling, we also induce the sample size by adapting the normal life time distribution model when the variable of the lognormal life time distribution is transformed and adapted to the model. In addition, the sample size for both the segments and increments can be induced by minimizing the asymptotic variance of test statistics of the segments and increments with consumer's risk met. We can assure the reliability of the mean life and B100p life time of the bulk materials by using the calculated minimum sample size.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.119-124
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• 2005

Decision of operation performance mode to minimize the energy consumption of urban rail vehicle. This paper analyses how much acceleration and deceleration of urban rail vehicle should be applied andhow to choose an operation mode to minimize energy consumption when train runs between station within the fixed operation time. The decided operation pattern satisfying the minimum energy consumption becomes a target trajectory and a basis for the controller design criteria. To make this goal it grasps the characteristics of urban rail vehicle, realize operation energy model of urban rail vehicle and verify the accuracy of embodied model the Matlab simulation with the same operation result of real route. It searches for operation pattern to minimize operation energy by changing the acceleration and deceleration on the imaginative route and proposes operation pattern minimizing energy consumption by applying real operation data between Dolgogee-Sukgye section of Seoul Metropolitan Subway Line 6.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 춘계학술대회 논문집
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• pp.431-436
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• 2002

Train driving should be satisfied to run fixed distance within given time, and it is desirable to minimize energy consumption. Minimizing energy consumption depends on the train operation modes by driver or automatic operation. In this article, an optimal operation to minimize energy consumption by changing modes of train operation by a driver is investigated. First, powering model, braking model and consumed energy calculation model are introduced by using Matlab software. The accuracy of the model established by simulation is compared with the real experimental data, which is obtained from an authorized institution. Second, several simulations under a variety of operations in the ideal track are executed, and then the optimal pattern of train driving is found.

• Structural Engineering and Mechanics
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• 제31권4호
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• pp.407-421
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• 2009

The present paper addresses the optimal design of composite laminates with the aim of minimizing free-edge delamination stresses. A technique involving the application of particle swarm optimization (PSO) integrated with FEM was developed for the optimization. Optimization was also conducted with the zero-order method (ZOM) included in ANSYS. The semi-analytical method, which provides an approximation of the interlaminar normal stress of laminates under in-plane load, was used to partially validate the optimization results. It was found that optimal results based on ZOM are sensitive to the starting design points, and an unsuitable initial design set will lead to a result far from global solution. By contrast, the proposed method can find the global optimal solution regardless of initial designs, and the solutions were better than those obtained by ZOM in all the cases investigated.

• 산업경영시스템학회지
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• 제34권3호
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• pp.90-96
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• 2011

Finding the critical path (or the longest path) on acyclic directed graphs, which is well-known as PERT/CPM, the ambiguity of each acr's length can be modeled as a range or an interval, in which the actual length of arc may realize. In this case, the min-max regret criterion, which is widely used in the decision making under uncertainty, can be applied to find the critical path minimizing the maximum regret in the worst case. Since the min-max regret critical path problem with the interval arc's lengths is known as NP-hard, this paper proposes a heuristic algorithm to diminish the maximum regret. Then the computational experiments shows the proposed algorithm contributes to the improvement of solution compared with the existing heuristic algorithms.

• 한국국방경영분석학회지
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• 제16권2호
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• pp.83-95
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• 1990

This paper addresses the problem of determining the optimal number of spares for a system consisting of multi-item parts. In commercial sector, the cost minimization is mainly considered as an objective functions in most inventory models. However, in the military inventory systems, it is more stressed on maximizing the system availability than minimizing the system cost because the field commander always wants the system to be in perfect working condition to prepare against an emergence case. In this point of view, this paper develops an inventory model which decides the optimal number of spares by minimizing units short and simultaneously achieving a certain level of system availability. Solution algorithms are derived using the generalized Lagrange multiplier approach and marginal analysis approach. Sample data and output results are provided and sensitivity analysis is performed as the level of system availability changes in order to decide the optimal number of spares and availability in terms of economic sense.

• Journal of Communications and Networks
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• 제6권2호
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• pp.147-155
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• 2004

In this paper, we propose an efficient sequencing technique, namely minimum Row time scheduling (MFTS), to manage variable-Iength message transmissions for single-hop passive starcoupled WDM optical networks. By considering not only the message length but also the state of the receivers and the tuning latency, the proposed protocol can reduce the average delay of the network greatly. This paper also introduces a new channel assignment technique latency minimizing scheduling (LMS), which aims to reduce the scheduling latency. We evaluate the proposed algorithm, using extensive discrete-event simulations, by comparing its performance with shortest job first (SJF) algorithm. We find that significant improvement in average delay could be achieved by MFTS algorithm. By combining the proposed message sequencing technique with the channel selection technique, the performance of the optical network could be further improved.