• 한국경영과학회지
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• 제22권2호
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• pp.79-97
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• 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.

• 한국경영과학회지
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• 제29권4호
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• pp.175-187
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• 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.

• 대한산업공학회지
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• 제15권1호
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• pp.23-30
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• 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.

• 한국멀티미디어학회논문지
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• 제8권1호
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• pp.62-70
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• 2005

본 논문에서는 모바일 ad-hoc 네트워크에 서 QoS 멀티캐스트 라우팅 을 지원하기 위한 구조들을 제안한다. 제안된 구조는 다음처럼 구성되어져 있다. 첫째, 안정된 멀티캐스트 서비스를 지원하기 위한 기반 구조로 이동성 기반 클러스터링을 제시한다. 둘째, 라우팅 경로와 네트워크의 안정성을 지원하고 평가할 수 있는 엔트로피 기반 모델을 제시하고 QoS 라우팅 지원 방안에 대해서 논의한다. 셋째, 앞에서 제시된 구조들을 사용하여 QoS 멀티캐스트 라우팅을 지원하기 위한 방법을 제시한다. 제안된 구조에 대한 성능 평가는 OPNET(Optimized Network Engineering Tool)을 사용한 모델링과 시뮬레이션을 통하여 이루어진다.

• 대한산업공학회지
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• 제25권1호
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• pp.35-46
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• 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.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.475-478
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• 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.

• 대한산업공학회지
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• 제20권2호
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• pp.19-30
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• 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.

• 대한산업공학회지
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• 제30권4호
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• pp.328-337
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• 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.

• 정보처리학회논문지C
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• 제18C권4호
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• pp.279-286
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• 2011

본 논문은 무선 센서 네트워크를 위한 라우팅(routing) 알고리즘에서 라우팅 구성을 위한 트래픽을 줄이기 위한 방법을 제안한 것이다. 제안된 방법은 일정 기간 동안 라우팅 메시지를 모아서 그 결과를 한번만 전송함으로써 라우팅 트래픽을 줄인다. 이 라우팅 트래픽을 모으는 방법은 네트워크의 경로 설정을 위한 시간이 증가하는 단점이 있다. 이러한 단점을 개선하기 위하여, 첫 하나 또는 몇 개의 라우팅 메시지는 즉시 전달하고 그 이후의 라우팅 메시지들은 일정 기간 동안 모아서 전달한다. 제안된 방법은 Qualnet 시뮬레이터와 C 언어를 이용하여 모델링하고 구현하였다. 실험을 통하여 제안된 방법들이 라우팅 트래픽을 효과적으로 줄일 수 있음을 보였다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2003년도 추계학술대회 및 정기총회
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• pp.325-328
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• 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.