• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2004년도 추계학술대회 및 정기총회
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• pp.8-12
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• 2004

In this study we consider a CONWIP system in which the processing times at each station follow a Coxian distribution and the demands for the finished products arrive according to a compound Poisson process. The demands that are not satisfied are backordered according to the number of demands that exist at their arrival instants. For this system we develop an approximation method to calculate order based performance measures such as the mean time of fulfilling a customer order and the mean number o: customer orders. For the analysis of the proposed CONWIP system, we model the CONWIP system as a closed queueing network with a synchronization station and analyze the closed queueing network using a product form approximation method. Numerical tests show that the approximation method provides fairly good estimation of the performance measures of interest.

• 한국경영과학회지
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• 제12권1호
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• pp.27-33
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• 1987

A stochastic model for an inventory system in which depletion of stock takes place due to random demand as well as random loss of items is studied under the assumption that the intervals between cussessive unit demands as well as those between cussessive unit losses, are independently and identically distributed random variables having negative exponential distributions with respective parameters .mu. and .lambda. It is further assumed that leadtime for each order is an outstanding-order-dependent random variable. The steady state probability distribution of the net inventory level is derived under the continuous review (S -1, S) inventory policy, from which the total expected coast expression is formulated.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2006년도 춘계공동학술대회 논문집
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• pp.1329-1333
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• 2006

This paper proposes a framework for product development including hardware and software components. The framework provides separation of the hardware dependent software, an integrated product development process, and integration of software components with product configurations and product structures. In order to separates the hardware dependent software, the framework considers product configuration modules and engineering changes of associated hardware and software components. The proposed product development process integrates development of the hardware dependent software into the existing product development process. In order to integrates the hardware dependent software with product configurations and product structures, the framework represents software components by existing product data models in Product Data Management (PDM). The framework is applied to development of a robot system including hardware and software components in order to show its effectiveness.

• 한국경영과학회지
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• 제37권3호
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• pp.95-116
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• 2012

The purpose of this paper is to show the effect of information sharing strategy on the supply chain performances. While traditional information sharing models assumed centralized stock information, recent supply chain practices often implement fully shared stock information, where real-time stock information is accessible on retailers. When retailers are competing with each other, this fully shared stock information may incur retailers' strategic order behaviors. Thus, this paper analyzes a simple two-level supply chain consisting of one warehouse and two identical competing retailers where the real time stock information is fully shared. The warehouse uses the traditional echelon stock policy. Under this environment the retailers' reorder decisions are derived using the order risk concept and the retailer competition mechanism is analyzed. Computational results show that the supply chain performace degradation in the fully shared stock information is quite significant, implying the importance of designing information sharing strategies in the supply chain design phase.

• 한국국방경영분석학회지
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• 제23권2호
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• pp.72-84
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• 1997

In this paper, we consider an economic order quantity(EOQ) and an optimal discount pricing policy for the monopsony related to the weapon system acquisition. In the monopsony case, a buyer wishes to maximize the profit. However, a seller wants to minimize the total inventory related cost since a buyer can determine the purchase price for the product. We develop a generalized version of EOQ model for the monopsony, including one seller-one buyer model and two seller-one buyer model. A model of buyer reaction to any given pricing scheme is developed to show that there exits a unified pricing policy which motivates the buyer to increase its ordering quantity per order, thereby reducing the joint(buyer and seller) ordering and holding costs in the system.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2008년도 추계학술대회 및 정기총회
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• pp.191-196
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• 2008

This paper presents an evolutionary algorithm for goal programming with preemptive priority. To do this, an evolutionary strategy is suggested which search for the solution satisfying the goals in the order of the priority. Two-sided assembly line balancing problems with multiple goals are used to validate the applicability of the algorithm. In the problems, three goals are considered in the following priority order: minimizing the number of mated-stations, achieving the goal level of workload smoothness, and maximizing the work relatedness. The proper evolutionary components such as encoding and decoding method, evaluation scheme, and genetic operators, which are specific to the problem being solved, are designed in order to improve the algorithm's performance. The computational result is reported.

• 한국경영과학회지
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• 제31권1호
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• pp.25-36
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• 2006

Consider a supply chain in which a vendor supplies a product to a buyer. We assume that the buyer's and vendor's inventory cost structures are different, resulting in differences in inventory order/delivery cycle times. Here, if one party insists on its individually optimal order/delivery quantity, the other party will suffer from mismatches in cycle times. Under this scenario, coordination contracts that make use of either a Net Term/Two parts Term Trade Credit or a Quantity Discount are designed to align individually optimal order Quantities. We compare and analyze the perform ances of these contracts. The focus of the comparison is the ability of contracts to generate a lower cost for the supply chain. We show that a Trade Credit policy can be effectively used to coordinate a supply chain. In many cases it will result in a lower supply chain cost compared to that achieved by using a Quantitative Discount policy.

• 한국경영과학회지
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• 제34권2호
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• pp.101-111
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• 2009

This paper considers two-sided assembly line balancing with preemptive multiple goals. In the problem, three goals are taken into account in the following priority order : minimizing the number of mated-stations, achieving the goal level of workload smoothness, and maximizing the work relatedness. An evolutionary algorithm is used to solve the multiple goal problems. A new structure is presented in the algorithm, which is helpful to searching the solution satisfying the goals in the order of the priority. The proper evolutionary components such as encoding and decoding method, evaluation scheme, and genetic operators, which are specific to the problem being solved, are designed in order to improve the algorithm's performance. The computational results show that the proposed algorithm is premising in the solution quality.

• 한국경영과학회지
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• 제16권2호
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• pp.125-125
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• 1991

This paper presents a framework for the hierarchical PPC(Production Planning and Control) in make-to-order environment with job shop. The characteristics of the environment are described as : 1) project with non-repetitive and individual production, 2) short delivery date, 3) process layout with large scales manufacturing. 4) job shops. The PPC in a make-to-order typically are organized along hierarchical fashions. A model is proposed for the hierarchical job shop scheduling based on new concepts of production system, work and worker organization. Then, a new integrated hierarchical framework is also developed for the PPC based on concepts of the proposed job shops scheduling model. Finally, the proposed framework has been implemented in the Electric Motor Manufacturing and the results showed good performance.

• 한국경영과학회지
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• 제11권1호
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• pp.44-50
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• 1986

In this paper, we find optimal policy for the (Q, r) inventory model under the lead time uncertainty. The (Q, r) inventory model is such that the fixed order quantity Q is placed whenever the level of on hand stock reaches the reorder point r. We first develop the single level inventory model as the basis for the analysis multi-level distribution systems. The functional problem is to determine when and how much to order in order to minimize the expected total cost per unit time, which includes the set up, inventory holding and inventory shortage cost. The model, then, is extended to the multi-level distribution system consisting of the factory, warehouses and retailers. In this case, we also find an optimal policy which minimizes the total cost of the contralized multi-level distribution system.