Research

year 1997 
author Sangbok Woo 
Keyword Integrated System, Loading, Tool allocation, Scheduling, Flexible Manufacturing System, Flexibility 
Abstract A Flexible Manufacturing System( FMS ) is an automated manufacturing system which pursues both the productivity of a transfer-line and the flexibility of a job shop simultaneously. In particular, the flexibility of FMS has been recognized as a major element for responding to dynamics of market environment and uncertainties of shop floor. In spite of such an importance, there were few researches which dealt with the effective use of flexibility throughout the production planning and scheduling of FMS. In order to efficiently utilize the flexibility of FMS, it is important to make a pertinent plan for the alternative machines in a given planning horizon. But, this is very complex because we should consider loading and tool-allocation constraints in production planning as well as precedence constraints in scheduling.

There were some researches which divided entire problems into two subproblems - loading and scheduling - and solved them hierarchically. Even a subproblem, however, it is too difficult to find an optimal solution in real time and to establish a relevant goal of the loading problem corresponding with the scheduling performance.

In this thesis, we attempt to solve the loading and scheduling problems of FMS in an integrated manner. So we propose an integrated system and its solution methodologies which can use the flexibility of FMS effectively, and make a decision about tool allocation, machine selection, and sequencing altogether.

The proposed system consists of two main modules, ´schedule generating module´ which makes partial schedules and ´tool-allocation checking module´ which investigates the feasibility of tool-allocation for unscheduled tasks. With interacting two modules, we settle the loading and scheduling problems. In the schedule generating module, we assume FMS scheduling problems as having multiple identical parts and alternative machines. According to characteristics of alternative machines, we classify the schedule generating module into three submodules - identical machines submodule, exclusive machines submodule, and non-identical machines submodule. In the identical machines submodule, we propose an optimal algorithm, a modified nondelay schedule generator which eliminates many duplicating partial schedules not affecting an optimal makespan solution, and show the validity and efficiency of the algorithm by theorems and experiments. In the exclusive machines submodule, we propose some dispatching rules which consider precedence relationships among multiple identical parts, and show the effectiveness of rules by experiments. In the non-identical machines submodule, we propose an schedule generating algorithm which is based on estimated workloads, and some dispatching rules which is devised to efficiently use the non-identical alternative machines, and show the superiority of proposed algorithms and rules by experiments. The schedule generating module can be used independently of the tool-allocation checking module in cases that constraints related to the tool-allocation become meaningless due to the introduction of an automated tool delivery system or a sufficient tool magazine, etc.

In the tool-allocation checking module, we propose a heuristic and a lagrangian relaxation method as well as optimization models. So, it is possible to solve real problems in allowed time limit. The tool-allocation checking module can be used as not only a submodule which solves the loading and scheduling problem, but also a means which indicates the production feasibility of parts selected initially or added in a given tool-allocation status. Experimental results show that in most cases the proposed integrated approach outperforms existing hierarchical approaches in the scheduling performance and the computational time required. In addition to that, the difference between two approaches tends to increase when the number of part types and the number of alternative machines increase and the tool constraints become tight. So, the results show that the proposed approach is very useful for practical problems. 
c PhD 

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번호 c year 제목 author
35 MS  1998  Design of Integrated BOM Management System supporting Multiple Views Keumseok Kang 
34 MS  1998  A Study on UML representation of CIM-OSA and availability of analysis and design pattern in CIM-OSA [1] Seungoh Han 
33 MS  1998  A study on an efficient real-time deadlock-free control algorithm by using graph-theoretic approach [27] Jungwoon Yoo 
32 MS  1997  A New Approach to Master Production Scheduling in the MRP environment [1] Sangdo Choi 
31 MS  1997  A Study on FMS Scheduling Problems Based on Priority Functions Generated by Genetic Programming ChangUk Kim 
30 MS  1997  A Scheduling Algorithm Considering Subcontractor and Machine Setup Cost in MRP Environment [1] Kichang Lee 
29 MS  1996  A Study on the Generation and DB Construction of Modular BOM [1] Yonggu Ji 
28 MS  1995  A Study on the Group Scheduling Problem with Sequence-dependent Set-up Times in a Multi-stage Cellular Manufacturing Systems Jaesoo Shim 
27 MS  1995  A study on Real-Time Collection of Shop Floor Data Using Speech Recognition [2] Namjoo Kim 
26 MS  1995  An Object-Oriented Framework for the Implementation of Distributed Shop Floor Control in FMS [2] Kyungsuk Lee 
25 MS  1995  A study on intelligent dispatching strategy in Automated Manufacturing Systems [5] Seongwoo Lee 
24 MS  1995  A Study on knowledge Acquisition for Simulation-based Scheduling Expert System [1] Soohyun Lee 
23 MS  1994  A Study on Development of a Knowledge Based Scheduler and Knowledge Acquisition through Simulation [1] Kitae Kim 
22 MS  1994  A Study on Distributed Shop Floor Control of Flexible Manufacturing Systems [4] Daeyoung Chung 
21 MS  1994  A Finitely Recursive Processes Approach to Modeling and Control of an FMC Jaeheuk Choi 
20 MS  1993  A Supervisory Control Approach to Rapid Implementation of Low-Level Control Software for FMC [1] Sangkyun Kim 
19 MS  1993  A Study on the FMS Shop Floor Control by Bidding among Autonomous Objects Jangsuk Moon 
18 MS  1993  A Study on Effects of Order Release Policies to Performance of Manufacturing Systems Choonghwan Ahn 
17 MS  1993  A Comparative Analysis of Production Control Policies under Production Uncertainty [5] Janghan Lee 
16 MS  1993  A Study on the Computer-Aided Process Planning for Rotational Parts Considering Machine Status [1] Sungbum Chun 
15 MS  1992  A Decision Support System for A Machine Specifications in Design of An FMS [6] Youngkwan Ko 
14 MS  1992  Event-Driven On-Line Operational Control of Flexible Manufacturing Systems Jonghun Park 
13 MS  1992  A Study on Production Planning Problems in a Flexible Machining and Assembly System [1] Sukang Lee 
12 MS  1991  A Study on Image Processing and CAD - Vision System Interface of Manufactured Parts [1] Kidong Kim 
11 MS  1991  A Study on the Layered Architecture for the Control of FMS Cells Hosub Shin 
10 MS  1991  A Study on Performance Evaluation of Production Plan for FMS Using Queueing Network [1] Sangbok Woo 
9 MS  1991  A Study on Scheduling Problem of Hierarchically Structured Products in FMS [1] Hanil Jeong 
8 MS  1990  A Study on Data Allocation Problems for Distributed Database Design [2] Kitae Shin 
7 MS  1990  A Fuzzy Linguistic Approach to the Part Selection Problem in FMS [1] Yoosuk Hong 
6 MS  1989  A Mathematical Decision Making Model for Real-Time Scheduling of an FMS Jonghan Kim 
5 MS  1989  An FMS Planning Algorithm Considering Tool Magazine Capacity and Alternative Routings [6] Chankwon Park 
4 MS  1989  A Study on the Computer and Database Location of Distributed Computer Systems in FMS [1] Kilsup Yang 
3 MS  1988  A Study on The Machine-Part Group Formation for FMS Planning and Operation Jaeyoon Kim 
2 MS  1988  Development of a Classification and Coding System through Fuzzy Sets Approach [1] Namkyu Park 
1 MS  1988  A Simulation Study on Operating Rules of FMS Considering Tool Change Byunghoon Yoo