• International conference on construction engineering and project management
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• 2013.01a
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• pp.141-144
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• 2013

This paper presents a system called a Cash-flow based Construction Schedule Optimization system(CfSO). The existing CPM effectively handles schedule and cost management. However, funding strategy should be considered to obtain maximum profit and to progress a project favorably. One of measures is to coordinate the contract terms between owner and subcontractors (or suppliers). Contractor may decrease the interest cost attributed to project financing by adjusting the timing of cash-inflows and cash-outflows. It is an excellent method maximizing profits. This paper presents a method to estimate the amount of a cash-flow occurred periodically by integrating the terms of contract into scheduling. The proposed method is implemented as a system prototype in Microsoft Excel. This system provides a user an automated tool that identifies an optimal schedule that secures maximum profit by adjusting start and finish times of non-critical activities' free-floats without affecting on the project completion time. This system supports a project manager to establish an optimum project schedule and identifies profitable contractual conditions against to a construction owner.

• The Journal of Fisheries Business Administration
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• v.36 no.3 s.69
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• pp.1-24
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• 2005

Korean fishery wage system has been evolved with the different titles. However, Since the law of fishing crew was enacted in 1984, the fishery wage system has been established as a rate system, which is a legal term. The present rate system in practice shows various contents and modalities, depending on fisheries and regions, but the fisheries of large trawl cooperative employ a rate system of fixed plus rate wage. However, such change did not transform basically the properties of pure rate scheme. As well known, fishing vessel owners face an awful lot of difficulty in managing and controlling effectively the production process because fishing activities are carried out in the seas remote from the land. Thus, it tend to be inevitable for vessel owners to employ a rate system to induce fishermen's positive motivation for promoting productivity and saving operating costs. However, the rate system has worked out as a driving force, which induce an increase in production more strongly under the expansion of vessel numbers and power and the keener competition of fishing activities. Even though the control mechanism of fishing instruments are well established, fishermen become naturally to have an incentive to increase their fishing effort for maximizing production since they are able to raise their shares by maximizing the quantity harvested. Thus, as far as the rate system exists, fisheries administration may have much difficulty in realizing its fishery management goals only through vessel reduction and fishing gear regulations. Also, under the rate system fishery management authority may be in face of a serious dilemma between the spontaneous rate system and vessel reduction policy. If the realistic aspect of the rate system is recognized and resource restoration and profit promotion are main policy goals, it is necessary to develop effective ways to control vessel owners' and fishermen's production-maximizing motives at an appropriate level. From this point of view, it seems reasonable to introduce TAC system by species or by fisheries into the existing fishery system. The research results suggest that if the fisheries administration could understand clearly the spontaneous fisheries wage system, it would know the norm of TAC and the basic reasons for illegal fishing activities and thus it would be able to develop and implement more realistic resource management policies.

• Environmental and Resource Economics Review
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• v.12 no.1
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• pp.75-90
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• 2003

In this paper we have shown that a Pigouvian tax is an adequate resolution of congestion externality to attain Pareto optimality using utility maximization. For this objective, taking an open access freeway as an example, we not only derived both marginal private benefit and marginal social benefit, but also assessed the divergence between marginal private benefit and marginal social benefit. As a result, we identified that the amount of a Pigouvian tax should be the same amount as the external time cost, which is the value of the marginal time cost to Individual a incurred by Individual b through freeway congestion. This Pigouvian tax coincides with the profit or wealth maximizing toll suggested by literature on the basis of profit maximization. In addition, because an open access freeway is accounted as common property resource, we proved that average social congestion cost is essentially equal to marginal private congestion cost in our model. Finally, we showed that the optimal value of trip derived in our model is the same as that generated on profit maximization approach.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.3
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• pp.21-28
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• 2020

Aftermarket refers to a market in which a company sells complementary goods, replacements of parts, and upgrade or maintenance services to consumers after selling them main durable goods. Intuitively, consumers who purchase main durable goods become major potential customers in subsequent aftermarket. Thus the existence of the aftermarket has a significant impact on pricing of the main durable goods as well as the aftermarket products. In this study, we analyze the effect of aftermarket on the pricing strategy for a company selling both main durable goods and aftermarket products. To do this we first divided the market into markets where the aftermarket products are indispensable and optional. Based on the proposed market types, the profit maximizing solutions are derived using two-period model, and the impacts of consumers' undervaluation of aftermarket product prices on pricing strategy are analyzed. The results can be summarized as follows : (1) Regardless of the market type, the total profits were found to be inversely proportional to the consumer's awareness accuracy of product prices in the aftermarket. This is in line with marketing efforts that sales companies have made intuitively to make consumers underestimate the cost of the aftermarket. (2) If aftermarket product is indispensable, only revenue from the aftermarket is sought. On the other hand, if aftermarket product is optional, revenue from the main durable good as well as the aftermarket product will be sought simultaneously. (3) Moreover, when aftermarket product is optional, the lower the awareness accuracy of consumers, the higher the price and profit of the main durable goods, while the lower the price and profit of the aftermarket products. This is contrary to the intuition that the lower the consumer's valuation of the costs of aftermarket, the more advantageous it would be to rely on aftermarket products rather than on main durable goods.

• Journal of Electrical Engineering and Technology
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• v.4 no.3
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• pp.346-352
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• 2009

The eventual goal of this paper is to help the generating companies and load-serving entities to choose appropriate relative levels of interconnected system versus bilateral trades while considering risk, and economic performance. In competitive power markets, electricity prices are determined by balance between demand and supply in electric power exchanges or bilateral contracts. The problem formulation is bilateral contract incorporated into Multi-area unit commitment with import/export and tie-line constraints. This proposed method considers maximizing own profit or minimize the operating cost among the generating companies in multi-area system. The feasibility of the proposed algorithm has been demonstrated using IEEE system with four areas and experimental results shows that proposed method is reliable, fast and computationally efficient

• Journal of Korean Society for Quality Management
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• v.33 no.4
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• pp.111-116
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• 2005

This paper considers the problem of optimally choosing the sub-process means of a mixture production process where two important ingredients are mixed. The quantity of each ingredient is controlled through each corresponding sub-process. The values of the sub-process mean directly affect the defective rate, production, scrap and reprocessing costs for the mixture production process. After inspecting every incoming item, each conforming item is sold in a regular market for a fixed price and any nonconforming item is scraped. A model is constructed on the basis of the selling price, production, inspection, and scrap and reprocessing costs. The goal is to determine the optimum sub-process mean values based on maximizing expected profit function relating selling price and cost components. A method of finding the optimum sub-process means is presented when the quantities of the two ingredients are assumed to be normally distributed with known variances. A numerical example is given and numerical studies are performed.

• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.4
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• pp.139-155
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• 2006

The facility location problem of this paper is distinguished from the maximal covering location problem and the flxed-charge facility location problem. We propose the maximal profiting location problem (MPLP) that is the facility location problem maximizing profit with multi-product. We apply to the simulated annealing algorithm, the stochastic evolution algorithm and the accelerated simulated annealing algorithm to solve this problem. Through a scale-down and extension experiment, the MPLP was validated and all the three algorithm enable the near optimal solution to produce. As the computational complexity is increased, it is shown that the simulated annealing algorithm' is able to find the best solution than the other two algorithms in a relatively short computational time.

• Journal of the Korean Operations Research and Management Science Society
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• v.33 no.2
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• pp.137-151
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• 2008

This paper deals with two shops dealing with single perishable product the fresh items are sold at a list price in the primary shop and the unsold items that have reached a certain allowed age are transferred to the secondary shop to be sold at a discounted price. It is assumed that the demand rates in two shops are Independent each other and can be expressed as a function of inventory level and price. With the objective of maximizing the profit under a Last-In-first-Out. (LIFO) issuing policy, we develop mathematical models for the following two cases : (1) opening primary shop only and (2) opening both primary shop and secondary shop. There are three decision variables, i.e., the reduced price in the secondary shop, the allowed age at the primary shop, and the order quantities at the primary shop. A solution procedure is developed based on tabu search and its validity is illustrated through a comparative study.

• Industrial Engineering and Management Systems
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• v.8 no.3
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• pp.162-170
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• 2009

This paper deals with a closed-loop remanufacturing system with one manufacturer and one remanufacturer. The manufacturer sells new products bearing the 'Extended Producer Responsibility (EPR).' It is assumed that the manufacturer's collection rate of used products depends only on the buy-back cost, while that of the remanufacturer depends on the minimum allowed quality level of used products in addition to the buy-back cost. Through the development of mathematical models with the objective function of maximizing profit, we study an efficient operation policy of each party. The decision variables are the unit selling price of new products and remanufactured products, the unit buy-back cost of the used products of the manufacturer and remanufacturer, and the minimum allowed quality level. The validity of the model is examined through numerical examples and sensitivity analysis.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.530-533
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• 2000

Recently, Manufacturers have recognized the importance of recycling because of the limitation of natural resources and new and proposed laws and legislations that assign responsibility to manufacturer for the ultimate disposal of their products and the environmental problems. In this paper, products assembled recyclable parts and non-recyclable parts are collected after consumer usage and go into a plant. And the collected recyclable parts are disassembled through the disassembly process and have three attributes - re-usable attribute, re-manufacturing attribute and dumping attribute. In this situation, we deal with a production planning for recycle-oriented manufacturing system. The proposed model maximizing the profit in a system is formulated as a mixed-integer linear programming. And then a numerical example is used to evaluate the effectiveness of the proposed model