• International Journal of Reliability and Applications
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• 제11권1호
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• pp.41-53
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• 2010

In the present paper we develop a mathematical model that facilitates the calculation of reliability of a complex repairable system having three units namely super priority, priority and ordinary. The system is analyzed with the application of Gumbel Hougaard copula when different types of repair possible at a particular state due to deliberate failure. Various reliability measures such as reliability, MTTF and profit function have been evaluated by using supplementary variable and Laplace transform techniques.

• 산업경영시스템학회지
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• 제32권4호
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• pp.192-202
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• 2009

Disassembly of products at their end-of-life (EOL) is a prerequisite for recycling or remanufacturing, since most products should be disassembled before being recycled or remanufactured as secondary parts or materials. In disassembly sequence planning of EOL products, considered are the uncertainty issues, i.e., defective parts or joints in an incoming product, disassembly damage, and imprecise net profits and costs. The paper deals with the problem of determining the disassembly level and corresponding sequence, with the objective of maximizing the overall profit under uncertainties in disassembly cost and/or revenue. The solution is represented as the longest path on a directed acyclic graph where parameter (arc length) uncertainties are modeled in the form of intervals. And, a heuristic algorithm is developed to find a path with the minimum worst case regret, since the problem is NP-hard. Computational experiments are carried out to show the performance of the proposed algorithm compared with the mixed integer programming model and Conde's heuristic algorithm.

• 대한안전경영과학회지
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• 제4권3호
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• pp.131-140
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• 2002

Today's environment of enterprise is changing, They have to face customer' demands with the right product, the right service and supply them at the right time. And also cut down logistics and inventory cost and bring up the profit as much as they can. This means the change of putting enterprise first in importance to putting customer first importance. therefore to correspond to customer's demand, shorting lead time is becoming a essential condition. The answer to this changes of environment is supply chain management. In this paper, It consolidates the necessity on a LTV(Life Time Value) and analyzes data which is concerned of Customer Value. Under the these environments, defines the LTV(Life Time Value) rule that can improve the customer value. We solved this problems using AHP(Analytic Hierarchy Process) for consistency at relationship matrix, AHP(Analytic Hierarchy Process) is based on Saaty's consistency rate. If consistency rate is under 0.1 point, preference rate's weights are acceptable. This study develop a program for AHP weights and support Satty's consistency rate.

• Industrial Engineering and Management Systems
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• 제9권4호
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• pp.303-311
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• 2010

In the last few years growing interest has been dedicated to supply chain management. Modeling complexity is added to supply chain coordination problem by accounting for reverse logistics activities. The objective of this paper is to extend inventory model of manufacturing factory with respect to the production of raw material of forward logistics and recycling material of reverse logistics. The proposed model is applied to a plastic recycling process plant located in Taiwan. The case study improvement scheme shows when the recycling rate of recycling material increases from 15% to 50%, the total inventory cost of manufacturing factory decreases by 12.82%, safety stock volume decreases by 41.19% and the reorder quantity is down by 50.96%. This paper finds whether the results of the model can reach the economic profit through quantitative analysis and encourages companies integrate reverse logistics into the supply chain system.

• 대한전기학회논문지
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• 제33권10호
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• pp.410-422
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• 1984

This paper presents a new practical method for optimal active and reactive power control for the economic operation in electrical power system, and the programs are developed for digital computer solution. The major features and techniques of this paper are as follows: 1) The method is presented for finding the equivalent active power balance equation applying the sparse Jacobian matrix of power flow equation instead of using B constant as active power balance equation considering transmission loss, and thus for determining directly optimal active power allocation berween generator unitw satisfying the equality and inequality constraints. 2) The method is proposed for solving directly the optimum economim dispatch problem without using gradient method and penalty function for both active and reactive power control. As a result, the computing time are reduced and convergence characteristic is remarkably improved. 3) Unlike most of conventional methods which adopt the transmission loss as a objective function for reactive power control, the total fuel cost of themal power plant is adopted as objective function for both active and reactive power control. consequently, more reasonable and economic profit can be achieved.

• 한국항해학회지
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• 제18권4호
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• pp.59-81
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• 1994

Korean property and liability insurance companies have underwrited hull insurance without proper undrewriting ability. But after April 1996. in case of Korean insurance market being opened the companies have to make hull insurance rate by themselves. Accordingly, in this study, the writer embodies important factors in making hull insurance rate by an empirical survey. In empirical survey, the writer used a questionnaire, 74 proper data was obtained from 96 officers working in making hull insurance rate in 12 Korean property and liablity insurance companies and 24 the foreign companies at home. Reliability was tested by Cronbach's Alpha and a conceptual validity by Factor Analysis. Hypothesis estabilished in this study was tested by Correlation and Multiple Regression Analysis. Results of testing hypothesis are as follows: Firstly, the traits of insurer and the assured influence significantly(P<0.05) on making hull insurance rate. Secondly, expected loss ratio, ship manager, ship's age, insured amount, level of the cost of repairing and salvage, shipowner, period of insurance, level of overseas rating, profit and expense, trading limits, ship's classification, conditions of insurance, and ship's size influence significantly(P<0.05) on making hull insurance rate.

• Asia pacific journal of information systems
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• 제1권1호
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• pp.117-145
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• 1991

IS changeback is regarded as an offective way to control the usage of computers and communication systems which are very much limited resources and whose costs are very high, In this paper, the problem of combining the optimal chargeback system which guarantees the efficiency with the Rawls'(1971) concept of fairness. Primary conclusion of this paper is that if the value function which represents the contributions of IS user to the firm's profit is evidit and there is no uncertainty about this contribution information, optimality can be achived without any loss of fairness using full cost allocation pricing. But if there is no significant differences among contribution of each user and there is no significant differences among users because of the managerial arbitrariness, From this point of view contingent chargeback system with which manager can find the golden middle between optimality and fairness by adjusting the 'efficiency coefficient' according to his/her organizational characterisics and environments is proposed. A heuristic of finding the appropriate efficiency coefficient is also suggested.

• 한국유기농업학회지
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• 제23권3호
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• pp.455-467
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• 2015

This study analyzed the regional economic feasibility of greenhouse gases (GHGs) reduction technology in paddy rice. Firstly, the impact of GHGs reduction technology on productivity, emission reduction, and costs is different from region to region. Secondly, the water irrigation system contributes to productivity, GHGs reduction, and water reduction, but the profit of paddy rice will decrease because of increase in fixed costs and variable costs. Thirdly, the economic feasibility shows that water-savings plot has a 1.41 in a benefit-cost ratio.

• 산업경영시스템학회지
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• 제14권23호
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• pp.71-100
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• 1991

Investment in FA facilities has been accerelated since 1986, turning point by labor strife in Korea firms. Most commonly adopted automation tech, in their manufacturing process consists of NC. Robotics, PLC, CAD/CAM now on and further confused system oriented FMS, CIM, etcs. undergoing. But for all their remarkable notices in manufacturing systems, The competitive position on product cost, quality, shorten delivery and profit has never been recovered in global swing market. To make some empirical suggestions with a view to competitive strategy of Korea firms by FA, to the conclusion largely FA tech. adoption can be justified only when its application on new product productions and improved the structure of products comparatively. Because of when it was applied in old production process. The effectiveness is very doubtful to the lacks of consistent and integrate manufacturing policy with the strategy of the fim and their poor standardization level in shop floors.

• 로봇학회논문지
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• 제17권4호
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• pp.387-396
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• 2022

Logistics industry still heavily relies on human labor in many field processes. However, robot applications in logistics are rapidly increasing, encouraged by technological progresses in robotics and cheaper robot solutions from competition between robot suppliers. Effectiveness of logistics automation are higher productivity for cost reduction and increased process capabilities for better profit, which is witnessed in many fields of logistics industry. In this paper, differences in logistics services - contract logistics, parcel, and fulfillment - are addressed, and characteristics and issues in application of various kinds of logistics robots such as AGV, AMR, ASRS, box/piece handling robots and robotic wearable devices are discussed. The advantages from flexibility and scalability of logistics automation by robots will benefit the future logistics business.