• Journal of the Korean Operations Research and Management Science Society
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• v.4 no.1
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• pp.51-67
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• 1979

This paper considers the problem of determining an optimal dynamic operating policy for a two-stage tandem queueing service system in which the service facilities (or stages) can be operated at more than one service rate. At each period of the system's operation, the system manager must specify which of the available service rates is to be employed at each stage. The cost structure includes an operating cost for running each stage and a service facility profit earned when a service completion occurs at Stage 2. We assume that the system has a finite waiting capacity in front of each station and each customer requires two services which must be done in sequence, that is, customers must pass through Stage 1 and Stage 2 in that order. Processing must be in the order of arrival at each station. The objective is to minimize the total discounted expected cost in a two-stage tandem queueing service system, which we formulate as a Discrete-Time Markov Decision Process. We present analytical and numerical results that specify the form of the optimal dynamic operating policy for a two-stage tandem queueing service system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1531-1535
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• 2008

In the past vertically integrated power system, the power utility forecasted power demand and invested new power plants to keep a system adequacy. However, in the competitive electricity markets, a principle part of the capacity investment is market participants who decided the investment to maximize their profit. Especially, one of the main factors in their long-term decision making is the retrieval of fixed costs (construction costs). This paper presents the capacity payment in electricity power markets. The capacity payment (CP) in Cost Based Pool (CBP) is needed to recover fixed costs. However, CP in CBP was applied not only recovering fixed costs but also ensuring supply reliability. In order to operate harmonious power markets, pool needs reasonable CP mechanism. This paper analysis CP using capacity proportion and Reliability Pricing Model (RPM).

• IE interfaces
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• v.20 no.1
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• pp.87-93
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• 2007

Burn-in is an engineering method for screening out products containing reliability defects which would cause early failures in field operation. Previously, various burn-in models have been proposed mainly focused on the trade-off of shop repair cost and warranty cost ignoring manufacturing yield. From the view point of a manufacturer, however, burn-in decreases warranty cost at the expense of yield reduction. In this paper, we provide a general model quantifying a trade-off between product yield and reliability, in which any defect distribution from previous yield models can be used. A profit function is expressed in burn-in environments for determining an optimal burn-in time. Finally, the method is illustrated with gate oxide failures which is an important reliability concerns for VLSI CMOS circuits.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.222-223
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• 2019

Many attention have been paid to the innovative technologies aiming at the paradigm shift such as the modular housing, pre-fabrication method, or long-life housing. Despite the government's efforts to diffuse the long-life housing, few case gained the high grades by applying various technologies required in the Long-life Housing Certification System. The concerns of cost increase and low profit are the main reason why most of the construction firms avoid the adoption of long-life housing. In this study, the variations of construction costs were analyzed according to the grades in the Long-life Housing Certification System. The results of this study will help the decision makers find the optimal solution in employing the long-life housing technologies during planning.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.36
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• pp.121-131
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• 1995

The purpose of a business's existence is to make profit. The objective of business can be attained through the most profitable activities such as the improvement of productivity, quality and the reduction of the manufacturing cost. In order to produce the goods with above said goal, it can be achieved by inducing and improving the manufacturing process. In this viewpoint, We'd like to develope an algorithm for improving productivity, quality and cutting the manufacturing cost under the limitation of the resources. This paper showed a practical method which gradually improves three factors [productivity, quality and cost-down] by calculating the effective value of single and multi process mutually.

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.4
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• pp.466-475
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• 1999

A backward Dynamic Programming(DP) model for the optimal facility replacement decision problem during a finite planning horizon is presented. Multiple alternative challengers to a current defender are considered. All facilities are assumed to have finite service lives. The objective of the DP model is to maximize the profit over a finite planning horizon. As for the cost elements, purchasing cost, maintenance costs and repair costs as well as salvage value are considered. The time to failure is assumed to follow a weibull distribution and the maximum likelihood estimation of Weibull parameters is used to evaluate the expected cost of repair. To evaluate the revenue, the rate of operation during a specified period is employed. The cash flow component of each challenger can vary independently according to the time of occurrence and the item can be extended easily. The effects of inflation and the time value of money are considered. The algorithm is illustrated with a numerical example. A MATLAB implementation of the model is used to identify the optimal sequence and timing of the replacement.

• Journal of Korean Institute of Industrial Engineers
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• v.33 no.3
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• pp.322-328
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• 2007

Highly standardized products are suitable for automated purchasing using electronic commerce technology, where the price becomes the most important factor. Suppliers can change the prices dynamically based on the inventory level and market situation in order to maximize the sales and profit. In the virtual marketplace where multiple customers purchase multiple standardized products from multiple suppliers repetitively, customers can purchase the required amount of each item as a dynamic bidding by allocating purchase orders to the suppliers based on the current price. Customers need a method to quickly determine the optimal allocation of orders to the suppliers using the dynamically changing data to minimize the total cost. We present a LP model which minimizes the sum of the total price plus transportation cost for this problem. Simulation results using random data show meaningful reduction of the total cost.

• Transactions of Materials Processing
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• v.24 no.3
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• pp.181-186
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• 2015

Many in the industrial world that consume high amounts of energy are trying to reduce energy when manufacturing their products. Energy saving during manufacturing is a cost reduction. Reduced cost is necessary for profit improvement. The Piston Under Drive Brake used in the current study is an automotive transmission part. The original machining after hot forging was changed to machining after cold forging of a plate in order to save energy and cost. Two extrusion shapes along the outer diameter caused decreased tool life because of the interrupted cut during turning. Therefore, a thickness reduction of two extrusion areas in the outer diameter was needed. The current study suggests an effective way to reduce the thickness of interrupted cut by using progressive blanking.

• Asia-Pacific Journal of Business
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• v.11 no.1
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• pp.17-26
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• 2020

Purpose - This paper studies the welfare impacts of behavior-based price discrimination (BBPD) when firms are asymmetric in quality improvement costs. Design/methodology/approach - To this end, we consider a differentiated duopoly model with an inherited market share, where firms first make quality decisions and then compete in prices according to the pricing scheme, namely, uniform pricing or BBPD. Findings - We show that BBPD increases social welfare relative to uniform pricing if the firms' cost gap is large enough. This is because BBPD induces more consumers to buy a high-quality product than under uniform pricing, and because a low-cost firm's profit loss from BBPD decreases as the cost difference increases. Research implications or Originality - Our analysis offers policy implications for markets where BBPD raises antitrust concerns, and quality competition prevails.

• Korean Journal of Construction Engineering and Management
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• v.4 no.4 s.16
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• pp.212-219
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• 2003

In construction project planning and control, a cost model performs a critical role such as cost determination on a contract stage and cost tracing. The model can maximize owner's profit and value within the project budget and optimize cost management works on overall construction implementation stages. A BoQ(Bill of Quantities) generally adopted in a unit price contract has been applied as an important tool for cost control and forecast. However a previous cost model based on the BoQ has shown limitations in that it requires too detailed information and heavy manpower on cost management and difficulty in keeping relationship with construction planning, scheduling and progress management. The each cost items and unit prices which constitute of construction works are individually very important management factors but the relative weight for each items and prices have a difference on the contents and conditions of each conditions of each construction works. In consideration of this structural mechanism of cost determination, this research is aimed at examining the critical factors affecting the construction cost determination and propose and verify a new cost forecasting model which is more simple and efficient and also keeps the accuracy of cost management.