• Journal of the Korea Society for Simulation
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• v.17 no.3
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• pp.75-83
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• 2008

A deadlock is a condition in which the excessive demand for the resources being used by others causes activities to stop and it is one of the important problems in process control system to detect and prevent deadlocks. While the reachability analyze methods or divide subnets for analyzing methods are well used, it requires a lot of times and effects to analyze the detection of the deadlock status. Furthermore, it could not be effective if the model is complex or huge. Therefore, it is necessary to develop a new and more efficient deadlock detection algorithm. In this paper, a deadlock detection conditions after analyzed the Petri Net using the transitive matrix has been proposed to solve these problems. For presenting the results, the suggested deadlock detection algorithm was also adapted to an illustrated FMS (Flexible Manufacturing System) model.

• Journal of Korean Institute of Industrial Engineers
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• v.12 no.2
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• pp.57-65
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• 1986

In the design and operation of Flexible Manufacturing Systems (FMSs), it is useful to have a tool with which one can evaluate system's performances under various conditions. As one of such tools, this study chooses the Linearizer algorithm which uses mean value analysis (MVA). Linearizer algorithm is known to be the most accurate one among the MVA based heuristic algorithms yet developed. Though, up until now, the method is solely used to evaluate computer system's performances, this study shows that the Linearizer algorithm can be adapted for FMSs and still produces accurate solutions. Numerical examples for various classes of FMSs are presented and compared with the results from other methods and simulations.

• Journal of the Korean Operations Research and Management Science Society
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• v.29 no.4
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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.

• Journal of the Korea Society for Simulation
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• v.4 no.1
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• pp.1-11
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• 1995

The model of a FMS (Flexible Manufacturing System) admits to a natural hierarchical decomposition of highly decoupled units with similar structure and control. The FMS fractal architecture model represents a hierarchical structure built from elements of a single basic design. A SES (System Entity Structure) is a structural knowledge representation scheme that contains knowledge of decomposition, taxonomy, and coupling relationships of a system necessary to direct model synthesis. A substructure of a SES is extracted for use as the skeleton for a model. This substructure is called pruned SES and the extraction operation of a pruned SES from a SES is called pruning (or pruning operation). This paper presents a pruning operation called recursive pruning. It is applied to SES for generating a model structure whose sub-structure contains copies if itself as in FMS fractal architecture. Another pruning operation called delay pruning is also presented. Combined with recursive pruning the delay pruningis a useful tool for representing and constructing complex systems.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.314-319
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• 2000

The working surface of a flexible grinding disk was characterized by means of an image processing, in which a picture of a disk surface was taken by the CCD camera and analyzed with the personal computer. As process conditions, depth of cut was changed to be 2 and 4 mm. From the captured image circles marked on the disk was regenerated using the edges detected with scale space filtering. In order to correlate the level of deformation to the distortion of the circles, intervals between each circle have been analyzed. Notable correlation has been observed between the intervals and the process conditions.

• Journal of Power System Engineering
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• v.4 no.4
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• pp.92-98
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• 2000

Modern manufacturing systems should cope with the frequent changes in a product model and disturbances in manufacturing process. The control system of such systems must cover a constant adaptation and high flexibility. Holonic Flexible Manufacturing Cell(HFMC) is introduced to handle these issues more successfully. It is based on the concept of autonomous co-operating agent, called 'Holon', which is a building block of a manufacturing system for transforming, transporting, storing and/or validating information and physical objects. In this paper the basic structure of the HFMC is represented by using Unified Modeling Language and Open architecture cell controller is developed for effective integration components of a manufacturing system. Also a new control model, called MuLOM(Multi-Layered Operation Model), is suggested to represent the control behaviour for a holonic flexible manufacturing cell control system.

• Journal of Korean Institute of Industrial Engineers
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• v.13 no.2
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• pp.117-128
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• 1987

A major problem in the adoption of advanced manufacturing systems such as F.M.S. (Flexible Manufacturing Systems) is the prerequisite economic justification process because of high investment needed for the acquisition and installation of F.M.S. While some of the benefits expected are readily quantifiable, others are very difficult or even impossible, using conventional method. Thus the investment in F.M.S. should be considered as a strategic decision rather than a tactical decision which concerns with only financial implications. In this paper we review papers on major justification techniques developed during thelast decade and identify the benefits of F.M.S. and describe the considerations in the justification of F.M.S. Also, we deal with the current and future research directions in justifying F.M.S.

• Annual Conference of KIPS
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• 2003.05c
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• pp.1697-1700
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• 2003

유연생산 시스템에서 스케줄링 문제는 기본적으로 조합 최적화 문제로서 NP-hard problem 으로 알려져 있으며 문제의 크기에 따라 복잡도가 지수적으로 증가하게 된다. 이러한 복잡도를 줄이기 위해 우리는 넷의 행위적인 속성에 따른 제어 흐름들의 집합을 병행적 기본 단위(BUC)로 정의하고, 이들을 종합화함으로 최종적인 스케즐링을 얻게 된다. 본 연구에서는 이러한 병행적 기본 단위로 넷을 분할하여 스케줄링을 분석하는 알고리즘을 제안한다.

• Journal of Korean Institute of Industrial Engineers
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• v.14 no.2
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• pp.131-141
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• 1988

As flexible manufacturing technology has become available across a broad range of applications, an increasingly large number of firms have confronted decisions about when to adopt the FMS technology and the size of FMS at that time. For small to medium size firms that should invest under budget limitation and high investment risk, proper size of FMS adoption at proper time is very important. In this paper the discrete optimal control theory has been used to make decisions about the size and timing of FMS capacity expansion over a planning period. Sensitivity analysis is presented for analysing the behavior of the model to variations of model parameters.

• JOURNAL OF ELECTRICAL WORLD
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• s.295
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• pp.74-79
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• 2001

최근의 전력시스템에 있어서는 국제화, 규제완화, 전력자유화의 추진에 따른 사회적 요청으로 대형정전사고의 방지 등 전력계통의 신뢰도를 확보하면서 설비형성의 슬림화$\cdot$고가동화 등 전력시스템의 토털코스트의 삭감을 도모하는 것이 기본적인 과제가 되고 있다. 이와 같은 상황에서 미쓰비시전기에서는 네트워크시대의 새로운 보호$\cdot$제어시스템용으로서 전력회사계통용 MELPRO-CHARGE 시리즈와 수용가계통용 MELPRO-DASH 시리즈를 개발, 실용화하였다. 이것들은 다음 그림에 표시하는 것과 같이 네트워크를 통하여 상위의 자동화시스템 및 감시제어시스템과 결합되어 보호$\cdot$제어기능의 고도화, 계통운용$\cdot$유지보수 시스템의 합리화를 실현하게 되는 것이다. 또한 MELPRO-CHARGE 시리즈는 고성능CPU의 채용으로 콤팩트화(동사 종래비의 약 1/2), 각종 사양에 대해 전용 생산툴에 의한 유연한 대응 등의 특징을 갖고 있다. 또 MELPRO-DASH 시리즈는 FA용 범용 네트워크에 의한 심플화와 보호$\cdot$계특기능 등의 특징을 갖게 된다. 본고에서는 전력계통 보호릴레이 기술의 동향과 새로운 보호$\cdot$제어시스템용 MELPRO 시리즈의 개발$\cdot$실용화 노력에 대한 개요를 소개한다.