• Journal of applied mathematics & informatics
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• 제42권2호
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• pp.379-390
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• 2024

This study proposes a fuzzy inventory model for managing large-scale production, incorporating cost considerations. The model accounts for two types of expenditure scenarios-parametric and exponential. Uncertainty surrounds holding costs, setup costs, and demand rates. The approach considers a supply chain system with a complex manufacturing process, factoring in transportation costs based on the quantity of goods and distance between the supplier and retailer. The initial crisp model is then transformed into a fuzzy simulation, incorporating specific fuzzy variables affecting inventory costs. The proposed method significantly reduces overall inventory costs for the entire supply chain. Retailer demand is linked to inventory levels, and vendor/distributor storage deteriorates over time. The fuzzy condition assumes hexagonal variables for all associated factors. The study employs the signed distance method for defuzzification to determine the optimal order quantity with hexagonal fuzzy numbers. Mathematical examples are provided to illustrate the practicality of the proposed approach.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.27-29
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• 2008

Announcements by many companies have shown that market interest and technical potential exist for AMOLEDs. DuPont Displays is developing solution processing technology designed to address the high cost of manufacturing AMOLEDs via vapor deposition methods. By printing OLED displays, we can reduce costs and can subsequently scale OLED manufacturing to a competitive motherglass size.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• 제24권5호
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• pp.521-529
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• 2015

Owing to a reliance on imported products from Europe and Japan, the use of logistics equipment with poor energy efficiency coupled with high maintenance costs can lead to high operating costs for some domestic logistic centers. To lower their operating costs, the logistic centers use motorized roller conveyors. In order to commercialize this process, it is necessary to establish the test criteria and assess the reliability of the process. Currently, there exists no standard verification method to test the reliability of motorized roller conveyors. In this study, we propose reliability assessment criteria for a: i) reliability test, ii) environmental test, iii) safety test, and iv) lifetime test.

• Journal of the Korea Institute of Building Construction
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• 제12권5호
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• pp.518-527
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• 2012

This study uses a hybrid estimation tool for effective cost data management of building projects, and develops a realistic cost estimation model. The method makes use of newly available information as the project progresses, and project cost and percentage progress are analyzed and used as inputs for the developed system. For model development, case-based reasoning (CBR) is proposed, as it enables complex nonlinear mapping. This study also investigates analytic hierarchy process (AHP) for weight generation and applies them to a real project case. Real case studies are used to demonstrate and validate the benefits of the proposed approach. By using this method, an evaluation of actual project performance can be developed that appropriately considers the natural variability of construction costs.

• ETRI Journal
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• 제44권6호
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• pp.936-944
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• 2022

The mobile network allows redundant transmission via disjoint paths to support high-reliability communication (e.g., ultrareliable and low-latency communications [URLLC]). Although redundant transmission can improve communication reliability, it also increases network costs (e.g., traffic and control overhead). In this study, we propose a reliability-guaranteed multipath allocation algorithm (RG-MAA) that allocates appropriate paths by considering the path setup time and dynamicity of the reliability paths. We develop an optimization problem using a constrained Markov decision process (CMDP) to minimize network costs while ensuring the required communication reliability. The evaluation results show that RG-MAA can reduce network costs by up to 30% compared with the scheme that uses all possible paths while ensuring the required communication reliability.

• International conference on construction engineering and project management
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.437-446
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• 2005

Recently as people's values are changing from development phase into running stage after quality of life, so that the needs of environmentally friendly construction are gradually increasing. Also populace discontent about the pollution during construction process such as the noise and vibration caused by construction machinery is increasing. Even though it is impossible to eliminate the construction pollution fully, it is necessary to make efforts to reduce construction pollution to a minimum. In terms of construction site operating, the first possible step for solving these matters directly is that the necessary sum of expenses must be secured as the environmental management costs in the conceptual phase. However, in fact, the environmental management costs have not been secured in the budget. Generally it is the major reason not arising proper activities to prevent the pollution in the construction site. The purpose of this research is to suggest the efficient budgeting method regarding Environmental management costs to ensure the necessary sum of environmental management expenses. To provide an efficient budgeting method, interviews with the person in charge of environment management was conducted. 78 construction sites was surveyed and environmental management costs were analyzed through their historical data from the survey. According to the results of analysis, the ratio of environmental management costs is revealed 0.45% of construction cost as average comparing 0.2% of legal limit. And usually the environmental management cost was appropriated into the safety management budget. So it is needed to isolate environmental management budget securely and modify the ratio of Environmental conservation Costs in Construction Technology Management Act.

• Journal of the Korean Society of Manufacturing Process Engineers
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• 제20권4호
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• pp.8-15
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• 2021

The effects on system availability, operation, and support costs were analyzed using the M&S system (MPS). The failure frequency items of current armored vehicles were identified and the MTBF of the identified items was improved. The results of this study suggest that when we reduce the frequency of failure, the availability increases, and the operation and support costs decrease. By improving the reliability of the failure frequency items, it becomes possible to upgrade or develop the weapons systems. Through this study, we confirmed that improving reliability will enhance combat readiness and reduce operation and support costs.

• Journal of the Korean Society of Clothing and Textiles
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• 제23권1호
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• pp.42-53
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• 1999

Global sourcing strategy is the one that apparel firms adopt in order to improve efficiency. Souring statesgies are not limited to the decision of sourcing country or vertical integration of sewing process Sourcing strategies include all the ecision of marketing process from the acquisition of fabric to distribution of products. The present study aims to analyze the soucing strategies of Korea apparel industry in global perspectives by applying transaction cost approach and aims to provide the implications for the future. The results are as follows ; (1) sourcing strategies in the dimension of domestic versus offshore soucing are determined by the experience in foreign business and the degree of fashionability of the product. (2) Firms tend to increase affshore soucing as they accumulate the experience in foreign business because they can decrease transaction costs as the perceived risks decrease (3) Also firms tend to source their products in foreign countries when the products are more fashionable. Brand loyalty of the product is a additional factor that increases the proportion of domestic sourcing. (4) Degree of vertical integration of sourcing is determined by the fashionability brand loyalty and the experience in foreign business. That is firms decrease the transaction costs by avoiding the investment to short life fashion products. However firms increase the control over the high reputation product by in house production. As the apparel firms tend to more marketing oriented and the national boundaries of business envrionment becomes permeable more efficient global sourcing strategies should be stablished, Besides the production costs nonproduction costs should be equallly considered in order to analyze the total costs.

• Industrial Engineering and Management Systems
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• 제8권4호
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• pp.221-227
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• 2009

There are customer services jointly provided by two facilities so that each customer will complete the course made up of both facilities' sub-services. The two facilities are assumed invested respectively by an infrastructure owner and one subordinate facility owner, whose partnership is built on their capital investments. This paper presents a mathematical model of Stackelberg competition between the two facility owners to derive their optimal Nash equilibrium. In this study, each facility owner's profit is consisted of fixed revenue fractions of sold services, operating costs (including depreciation cost) and maintenance costs of her facility. The maintenance costs of one facility are incurred both by failures and deterioration due to usage. Moreover, for both facilities, failures are rectified immediately by minimal repairs and preventive maintenance is carried out at a fixed time epoch. Additional assumptions are also employed to develop the model such as customer arrivals are manipulated to follow a Poisson process, and each facility's lifetime is independently Weibull-distributed. The Stackelberg game proceeds as follows. At the first stage of decision making process, the infrastructure owner (acting as a leader) decides the allocation of revenue shares based on her self-interest. After observing the allocation of revenue shares, the subordinate facility owner determines her own optimal price of services. This paper investigates actions and reactions of the two partners in the system. Then analytical conditions are proposed to achieve a unique optimal Nash equilibrium. Finally, some suggestions for further research are discussed.

• Journal of Korean Institute of Industrial Engineers
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• 제34권3호
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• pp.337-343
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• 2008

The problem of determining the optimum metal plating thicknesses on the plane and curved surfaces of an electronic part is considered. A lower specification limit for the plating thickness is usually pre-specified. In most applications, the plating thickness on the curved surface is proportional to that on the plane surface. The proportion can be adjusted by adding chemical catalysts to the plating fluid. From the economic point of view, nonconforming items with a thickness smaller than the lower specification limit incur rejection costs, such as rework and scrap costs, while a thicker plating may incur an excessive material costs. In this article, an economic model is proposed for simultaneously determining the target plating thickness and the ratio of the plating thickness on the plane surface to that on the curved surface. An illustrative example demonstrates the applicability of the proposed model.