• Journal of the Korean Operations Research and Management Science Society
• /
• v.22 no.2
• /
• pp.79-97
• /
• 1997

Many dispatching rules have been developed for the on-line control of product flow in a job shop. The introduction of a flexible manufacturing system (FMS) has added a new requirement to classical job shop control problem : the selection of machines by parts of different types. An FMS can keep a great deal of information on the status of the system, such as information on what is scheduled in the near future, with great accuracy. For example, the knowledge of the time when the next part will arrive at each machine can be neneficial for the routing. This paper tests the effects of the use of this knowledge for part routing on the parts flow time (sum of the time for waiting and service) under a simple routing procedure- a look-ahead routing procedure. A test under many operating conditions shows that the reduction of part flow time from the cases without using this information is between 1% and 11%, which justifies more study on this routing procedure at real production sites when machine capacity is a critical issue. The test results of this paper are also valid for other highly automated systems such as the semi-conductor fabrication plants for routing when the arrivals of parts in the near future are known.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.29 no.4
• /
• pp.175-187
• /
• 2004

We consider the simultaneous selection of part routes for multiple part types in Flexible Manufacturing Systems (FMSs). Using an optimization framework we investigate two alternative route assignment policies. The one, called routing mix policy in the literature, specifies the optimal proportion of each part type to be produced along its alternative routes, assuming that the proportions can be kept during execution. The other one, which we propose and call pallet allocation policy, partitions the pallets assigned to each part type among the routes. The optimization framework used is a nonlinear programming superimposed on a closed queueing network model of an FMS which produces multiple part types with distinct repeated visits to certain workstations. The objective is to maximize the weighted throughput. Our study shows that the simultaneous use of multiple routes leads to reduced bottleneck utilization, improved workload balance, and a significant increase in the FMS's weighted throughput, without any additional capital investments. Based on numerical work, we also conjecture that pallet allocation policy is more robust than routing mix policy, operationally easier to implement, and may yield higher revenues.

• Journal of Korean Institute of Industrial Engineers
• /
• v.15 no.1
• /
• pp.23-30
• /
• 1989

The routing flexibility in FMSs can be achieved through two levels : the parallel operations and the alternative stations. To accommodate this pertaining flexibility for part routing in FMSs, a hierarchical routing principle is developed which considers both the routing flexibility and the performance effectiveness, which can also be easily implemented. For the proper implementation of this routing algorithm, the required information flow is identified which turns out to be very simple.

• Journal of Korea Multimedia Society
• /
• v.8 no.1
• /
• pp.62-70
• /
• 2005

In this paper, we present an architecture for supporting QoS multicast routing in mobile ad-hoc networks. The proposed architecture consists of three parts as follows. The first part is a mobility-based clustering as underlying structure for supporting stable multicast services. In the second part, a framework which can support and evaluate the stability of route and network for supporting QoS routing is presented. In the third part, we describe a method which uses two structures of the first and second parts for supporting QoS multicast routing services. The performance evaluation of our proposed architecture is accomplished via modeling and simulation using the Optimized Network Engineering tool(OPNET).

• Journal of Korean Institute of Industrial Engineers
• /
• v.25 no.1
• /
• pp.35-46
• /
• 1999

The introduction of general purpose machining centers and the information system based on computer network has added a new control problem to the classical job shop control problems: a routing problem. A routing problem is to determine the machine on which a part will be processed. The modern manufacturing systems are given much system status information including the arrival time of the future parts via the computer network for automation. This paper presents and tests the performance of a routing procedure, LARP(Look-Ahead Routing Procedure) which uses look-ahead information on the future arrival of parts in the system. The manufacturing system considered in this paper has multi-stations which consists of general purpose machines and processes parts of different types. The application of LARP under many operating conditions shows that the reduction of part flow time and tardiness from the cases without using this information is up to 8% for flow time and 21% for tardiness. The procedure introduced here can be used for many highly automated systems such as an FMS and a semi-conductor fabrication system for routing where the arrivals of parts in the near future are known.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2004.05a
• /
• pp.475-478
• /
• 2004

Tool costs can comprise a significant part of the total operating costs of Flexible Manufacturing Systems. We address the problem of determining the optimal processing times of individual operations and routing mix in FMSs with multiple routes for each part type in order to minimize tool cost, subject to meeting a throughput constraint for each part type. The problem is formulated as a nonlinear program superimposed on a closed queueing network of the FMSs under consideration. Numerical examples reveal the potential of our approach for significant saving in tool costs.

• Journal of Korean Institute of Industrial Engineers
• /
• v.20 no.2
• /
• pp.19-30
• /
• 1994

Generally, a planning problem in a flexible manufacturing system is considered to be a composite of three interdependent tasks : part selection, loading, and routing mix. This research presents a mathematical model which can concurrently solve part selection, loading, and routing mix problems, so the problems that are caused by treating the planning problems independently are solved. The mathematical model is aimed to minimize system unbalance and the number of late parts, including constraints such as machine capacity, tool magazine capacity, and tool inventory. To illustrate the application of the model, an example is included. Solution procedure based on Lagrangian relaxation is also suggested for larger-sized problems.

• Journal of Korean Institute of Industrial Engineers
• /
• v.30 no.4
• /
• pp.328-337
• /
• 2004

Tool costs can comprise a significant part of the total operating costs of Flexible Manufacturing Systems. We address the problem of determining the optimal processing times of individual operations and routing mix in FMSs with multiple routes for each part type in order to minimize tool cost, subject to meeting a throughput constraint for each part type. The problem is formulated as a nonlinear program superimposed on a closed queueing network of the FMSs under consideration. Numerical examples reveal the potential of our approach for significant saving in tool costs.

• The KIPS Transactions:PartC
• /
• v.18C no.4
• /
• pp.279-286
• /
• 2011

This paper proposes techniques for wireless sensor network routing algorithm with small routing traffics. It reduces routing traffic by gathering routing messages for fixed duration of time and the routing message for the configuration result is sent once. The routing traffic gathering technique has disadvantage of longer network configuration time. To overcome this, first one or first few routing messages are delivered immediately and later routing messages are gathered for fixed duration of time. The proposed scheme was modelled and implemented in Qualnet simulator using C language. Experimental results show that the proposed techniques are effective for reducing routing traffics.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2003.11a
• /
• pp.325-328
• /
• 2003

Fierce competition in today's global markets, the heightened expectation of customers have forced business enterprises to invest in, and focus attentions on, their Supply Chains, Also Cross Docking is an essential part of SC, and integrating Cross Docking with vehicle routing scheduling is needed to smoothly link the physical flow of SC, However, there is no the mathematical model which focuses on Cross Docking with vehicle routing scheduling. Therefore, the integrating model considers Cross Docking and vehicle routing scheduling will be developed in this paper. And the solution based on Tabu algorithm to this model will be provided.