• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.43
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• pp.249-263
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• 1997

This paper addresses the parts route selection and economic design in flexible manufactuirng system (FMS). Parts are processed through several stage workstations according to operation sequences. The machine of each workstation can do multiple operation functions. And the operation stage of a part can be processed in several workstations, which are non-identical in functional performance. The objective of this paper is to determine the processing routes of parts, number of machine at each workstation, number of vehicle and makespan time. Two models are suggested. One is assumed that the operation stage of parts can be processed at the only one among several available workstations. Other is assumed that the operation stage of parts is allowed to be processed at several workstations. Parts are transported by automated guided vehicles (AGVs). The decision criteria is to minimize the sum of processing cost, travel cost, setup cost and overhead cost. The formulation of models is represented. A solution algorithm is suggested, and a numerical example is shown.

• Journal of the Korea Society for Simulation
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• v.17 no.1
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• pp.9-16
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• 2008

The sink mobility can request frequent routing change in sensor networks. By active mobility a sink can gather needed information easily so that the network availability will be higher. However, instead static sink system, the connection between sensor nodes and a mobile sink can be changed continuously. That is, the rerouting should be implemented caused by the routing alteration. It is two connection setups for the mobile sink system: the connection from sink to sensor nodes and the connection from sensor nodes to sink. However, sensor nodes actually have many functional limitations. Hence, the low cost scheme will be needed for the connection setup from sensor nodes to the mobile sink. In this paper, we propose an agent scheme to the connection setup from sensor nodes to the mobile sink. The agent scheme provides the reliable setup scheme to the connection by using an agent sector.

• Journal of the Korean Operations Research and Management Science Society
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• v.17 no.3
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• pp.27-46
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• 1992

This paper considers an (r, Q) policy for operation of a multipurpose facility. It is assumed that whenever the inventory level falls below r, the model starts to produce the fixed amount of Q. The facility can be utilized for extra production during idle periods, that is, when the inventory level is still greater than r right after a main production operation is terminated or an extra production operation is finished. But, whenever the facility is in operation for an extra production, the operation can not be terminated for the main production even though the inventory level falls below r. In the model, the demand for the product is assumed to arrive according to a compound Poisson process and the processing time required to produce a product is assumed to follow an arbitary distribution. Similarly, the orders for the extra production is assumed to accur in a Poisson process are the extra production processing time is assumed to follow an arbitrary distribution. It is further assumed that unsatisfied demands are backordered and the expected comulative amount of demands is less than that of production during each production period. Under a cost structure which includes a setup/ production cost, a linear holding cost, a linear backorder cost, a linear extra production lost sale cost, and a linear extra production profit, an expression for the expected cost per unit time for a given (r, Q) policy is obtained, and using a convex property of the cost function, a procedure to find the optimal (r, Q) policy is presented.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.42
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• pp.99-109
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• 1997

This paper considers to determine the processing workstation of parts and number of machines at workstations in multi-stage manufacturing system. Several part types are processed simultaneously through multi-stage, which consist of several workstations. The machines in each stage are identical in function, but non-identical in functional performance depending on workstations. Two models are suggested. One is assumed that a part type can be processed at the only one workstation in each processing stage. The other is assumed that a part type can be processed at several workstations. Decision criteria is to minimize the sum of the processing cost, travel cost and machine setup cost. Model formulations are presented, and a numerical example is shown.

• IE interfaces
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• v.14 no.3
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• pp.318-325
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• 2001

In this paper, we estimate the investment cost for the IMT-2000 services in Korea. The network elements for the IMT-2000 system are drawn out and the required number of base stations(Node-B) is predicted by using the coverage of the base station. With the assumption of the 2-generation mobile communications network configuration, the number of radio network controllers(RNC's) and core network facilities is estimated. We also setup different scenarios by considering the utilization of the transmission facilities between base stations, RNC's and switching systems, and then evaluate the investment cost for each scenario.

• Journal of information and communication convergence engineering
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• v.10 no.4
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• pp.349-358
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• 2012

Over a wireless sensor network (WSN), accurate localization of sensor nodes is an important factor in enhancing the association between location information and sensory data. There are many research works on the development of a localization algorithm over three-dimensional (3D) space. Recently, the complexity-reduced 3D trilateration localization approach (COLA), simplifying the 3D computational overhead to 2D trilateration, was proposed. The method provides proper accuracy of location, but it has a high computational cost. Considering practical applications over resource constrained devices, it is necessary to strike a balance between accuracy and computational cost. In this paper, we present a novel 3D localization method based on the received signal strength indicator (RSSI) values of four anchor nodes, which are deployed in the initial setup process. This method provides accurate location estimation results with a reduced computational cost and a smaller number of anchor nodes.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.4
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• pp.25-34
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• 2011

In this paper, we investigate an inventory system where a single manufacturer purchases and processes raw materials in order to deliver finished goods to multiple retailers. Earlier study in this type of supply chain only consider a single raw material in order to produce finished goods, but we consider multi-raw materials in order to produce finished goods. Also, we develop an iterative solution procedure to find the order quantity for the finished goods and raw materials, and the number of shipments between manufacturer and retailers that minimizes the total cost per unit time of the raw materials ordering and holding, manufacture's setup and finished goods holding, the retailer's ordering and inventory holding. Numerical examples are presented to illustrate that jointly considering the total cost results in less total cost than that of considering them separately.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.36 no.4
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• pp.31-37
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• 2013

In this paper, we develop an efficient approach to solve a continuous review inventory system with a budget constraint when the semi-finished product and optional components are required to be assembled. We are, in particular, interested in a budget constraint that includes a service level. The service cost, such as labor and facility costs, tends to increase as the service level increase, and it makes the problem difficult to solve. Assuming that the reorder point for a semi-finished product is given, we show that the order quantity for the semi-finished product and the order quantity and reorder point for optional components can be determined by minimizing the total cost that includes setup cost, inventory holding cost, and shortage cost. The performance of the proposed approach is tested by numerical examples. By using sensitivity analysis, we conclude that, as the reorder point for semi-finished product increases, the order quantity for semi-finished product increases, whereas the order quantity and reorder point of optional components decreases.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.2
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• pp.57-65
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• 2009

In continuous review inventory model, (${\varrho}$, ${\gamma}$) system, order quantity(${\varrho}$) and reorder point(${\gamma}$) should be determined to calculate inventory-related cost that consists of setup, holding, and penalty costs. The procedure to obtain the exact value of ${\varrho}$ and ${\gamma}$ is complex. In this paper, a regression analysis is proposed to get the approximate inventory-related cost without the determination of ${\varrho}$ and ${\gamma}$ in the case that the standard deviation(${\sigma}$) of the lead time demand is small or that the mean(${\mu}$) of the lead time demand is proportional to ${\sigma}$. To save inventory-related cost, central warehouses with (${\varrho}$, ${\gamma}$) system can be built. Central warehouse can provide some stores with products with the consideration of the tradeoff between inventory-related cost and transportation cost. The number and the location of central warehouses to cover all the stores are determined by a regression-based approach. The performance of the proposed approach is tested by using some computational experiments.

• Journal of Korean Society of Transportation
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• v.28 no.6
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• pp.17-24
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• 2010

As various social problems occur due to increasing traffic accidents, the government has setup and executed strong safety policies. As a result, the number of traffic accidents and the death toll have been decreasing in recent years. However, the setup and execution of the various policies for reducing traffic accidents cost much, so it is necessary to evaluate the cost-effectiveness of each policy. In the present study, enforcement by means of an unmanned over-speed enforcement system, the enforcement effect of which was proven good compared to the cost required for traffic enforcement, is compared with enforcement by policemen. As a result of the comparison, the average speed was 82.66 km/h before the use of unmanned systems and policemen; the average speed with manned enforcement was 70.57 km/h; and the average speed with unmanned systems was 67.85 km/h. The speed limit violation rate was 65% before the use of unmanned systems and policemen; 32% with manned enforcement; and 15% with unmanned systems. Considering the kinds of vehicles, the average speed and violation rate were highest among private cars, then vans, and then trucks.. Considering lanes. The accident rate was estimated based on the above results, and the input cost-to-advantage was estimated. The annual cost-to-advantage was estimated by comparing the above estimated values with the conditions before the unmanned over-speed enforcement system. Subsequently, the enforcement by policemen showed a negative advantage of 76,130,590 won, and the enforcement by the unmanned system showed a positive advantage of 38,577,670 won.