• 동력기계공학회지
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• 제9권4호
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• pp.181-186
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• 2005

Because of advanced control technology, Shop floor control system of various kinds of equipment and machinery need a web based remote monitoring to control process efficiently. This paper presents the development of Operation Control System. Operation Control System(OCS) is based on intelligent web monitoring, so that OCS is improved the working condition for the line of heat treatment process and the product's quality. The developed OCS is consisted of Atmega128(MCU) based on embedded system, running the data logging of the line of heat treatment process. Web monitoring system is based on CS8900 ethernet controller and TCP/IP for remote monitoring responsibility between a server and clients and controlling the progress of entire system. The developed OCS is implemented on the line of heat treatment process and shows the improvement of environment condition, product's quality and efficiency of process line.

• 한국정밀공학회지
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• 제9권4호
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• pp.36-43
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• 1992

This paper presents a hierarchical real-time operation control and monitoring scheme of the FMS/CIM center which has been implemented at the Automation and Systems Research Institute of Seoul National University. The hierarchical structure of the whole scheme consists of three lavers. The upper layer is in charge of on-line scheduling, computer network control, shop-floor monitoring and command generation for AGV dispatching, machining, assembly, inspection, set-up, etc. The middle layer has six modules, which are installed in the FMS host computer with the upper layer and run on the multi-tasking basis. Each module is connected to one of six cell controllers distributed in the FMS model plant and transfers operation command down to each cell controller through the Ethernet/TCP-IP local area network. The lower layer is comprised of six cell control software modules for machining cell, assembly cell, inspection cell, set-up stations. AS/RS and AGV. Each cell controller reports the status of the manufacturing facilites to the middle layer as well as ecxecuting the appropriate sequence control of the manufacturing processes.

• 한국정밀공학회지
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• 제16권4호통권97호
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• pp.85-94
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• 1999

Reconfiguration, expansion, or new establishment of FMS requires the availability of a shop floor control (SFC) system relevant to the FMS since it is closely related with the hardware component of FMS. Due to the expensive cost of its development, significant research efforts have been made to develop an SFC system that is reusable. This paper presents Abstract Machine Tool (AMT) approach applied to develop an SFC sytem that is reusable without additional programming. The AMT model enables us to design the SFC system independently of the hardware-dependent attributes of euqipment; an AMT models a workstation by abstraction and presents an equipment-independent interface to machining cell controller. Specifically, we describe how we formalize the interfaces among equipment in order to build an AMT and how we design the machining cell control software based on AMT models. We also present MACHINIST the machining cell control system for IAE-FMS plant as an implementation example.

• 대한산업공학회지
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• 제23권2호
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• pp.403-420
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• 1997

In this paper, we examine the effect of production uncertainty to production control policies. First, we examine two famous production control policies, namely, MRP and JIT from the view point of shop floor control perspective, and analyze the differences between them due to demand fluctuations and activity time variations. Second, we conduct simulation studies on MRP and JIT to draw out the effects of demand fluctuations and activity time variations. Demand fluctuations are further classified into demand lumpiness and demand irregularity. And, activity time variations are further classified into stationary time variations and non-stationary time variations. Experimental results show that, in terms of demand fluctuations, MRP is affected by demand lumpiness, but JIT by demand irregularity. And we also see that both MRP and JIT are influenced by stationary time variation with respect to activity time variations.

• 대한전기학회논문지
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• 제43권3호
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• pp.492-503
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• 1994

In this study, the control and scheduling of the flexible manufacturing cell (FMC) is discussed, which can perform the mixed production and relieve the effect of machine failure. The control of the FMC isvery complex task due to the property of multiple jobs and the dynamically changing states. For effective control of proposed FMC, the hierarchical scheme is introduced and the functions of each levels are defined. Especially for the control functions of shop floor level and cell level, the intelligent scheduler is implemented. To show the efficiency of the intelligent scheduler, the production method fo the existing assembly lines was evaluated and compared with the proposed intelligent FMC method. The results from the production performance show that the proposed method is superior to the existing method in various performance indices.

• 품질경영학회지
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• 제26권1호
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• pp.108-125
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• 1998

The EWMA(Exponentially Weighted Moving Average) has recently received a great deal of attention in the quality control literature as a process monitoring tool on the shop floor of manufacturing industires, since it is easy to plot, to interpret, and its control limits are easy to obtain. Most a, pp.ications of the EWMA for process monitoring have concentrated on the problem of detecting shifts of a process mean and a process standard deviation with ARL(Average Run Length) properties. But there may be the necessity of controlling linearity on product quality such as the correlation coefficient to the process operator. Control managers may want to protect the increase of a process correlation coefficient value, such as 0, between two variables of interest. However, there are few studies concerned on this part. Therefore, we propose EWMA models for a process correlation coefficient using two transformed statistics, T-statistic and (Fisher's) Z-statistic. We also present some results of simulation by SAS/IML and compare two models.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.354-357
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• 1996

Virtual Manufacturing System(VMS) is an integrated computer based model which has physical, logical schema and behavior of real manufacturing system. In this paper, an integrated scheduling system is developed to simulate and control a Virtual Factory. A workflow model is constructed to define and analyze the structure of a VMS. On-line dynamic dispatching system is developed using MultiPass algorithm and scheduling system considering dynamic CAPP is carried out. Integrated scheduling system developed in this paper reduces the discrepancies between virtual model and real manufacturing system, and control of real shop floor is possible.

• 한국컴퓨터정보학회지
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• 제14권2호
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• pp.159-164
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• 2006

제조실행시스템(MES: Manufacturing Execution System)은 현장(shop floor)에서 작업을 수행하기 위한 제반 활동 (스케줄링, 작업 프로세스, 품질관리, 등)을 지원하기 위한 관리 시스템이다. 특히, MES는 생산계획과 실행의 차이를 줄이기 위한 시스템으로 현장상태의 실시간 정보제공을 통하여 관리자와 작업자의 의사결정을 지원하는 기능을 수행한다. 실시간 정보처리를 위한 MES는 최근 많은 관심을 가지고 있는 RFID의 Data를 모델링하고, 제조부터 판매까지 각 프로세스 내의 제품을 모니터링 하는 기능이 필요하다. 그러나, RFID가 부착된 제품이 프로세스 과정에 있어서, tag, reader의 오작동, 고의적 파손, 분실, 주변 영향으로 인해, 리더기가 tag를 읽지 못하는 경우, 제품의 위치를 모니터링 할 수 없다. 이러한 경우, 불확실한 정보를 가지고 제품의 경로를 추적하여야만 한다. 본 논문은 신속하게 제품을 찾기 위해, RFID와 Bayesian Network을 이용한 MES를 제안하고 성능을 평가하였다.

• 산업경영시스템학회지
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• 제41권4호
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• pp.22-33
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• 2018

Recently domestic manufacturing companies have been experiencing worsening profitability and stunted growth due to the long-term economic recession and the rapid rise of developing countries such as China and Southeast Asia. These difficulties force many companies to concentrate their core competencies on new value creation and innovation in order to gain momentum for new growth. Enterprise Resource Planning (ERP) has been considered as one of viable solutions. Among the various modules in ERP, shop floor control function in the production management module is rather limited. In order to overcome this problem, Manufacturing Execution System (MES) has been used as a subsystem which has a strong information gathering power and flexibility. Both systems interact closely with each other. In particular, ERP requires fast, accurate shop floor information at MES. This paper describes how to synchronize relevant information between ERP and MES with theory of constraints (TOC). The processing time information transmitted from the MES workplace is received at the ERP workplace. In the process, the received processing time is causing information distortion in ERP, when the information gathering standard of MES is different from the ERP information interpretation standard. The Drum-Buffer-Rope theory of TOC was applied to resolve this problem, therefore, information synchronization between both systems was made. As a precondition, the standard time of the upper ERP system was rearranged according to the capacity constraints resource. As a result, standard time restructuring has affected changes in labor costs. Standard labor costs have come close to actual ones, and information synchronization of MES transmission data has improved the reliability of standard product costs, such that it enabled various company-wide restructuring actions to be much more effective.

• 한국정밀공학회지
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• 제19권7호
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• pp.116-124
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• 2002

The planning of part feeder and other manufacturing automation equipments is almost always underestimated. Planning ahead for those crucial pitfalls can permit steps to take to minimize heir impacts, especially if the problems can be discovered in the planning phase, not on the shop floor. Planning process is an engineering process, namely a series of trade-offs. The effective trade-offs in the shortest amount of time can be possible with the help of a computer-aided ngineering (CAE) technique. The main parts of CAE fur part feeder are database system of fabricated workpiece parts, part feeders, part feeder components. In this study, a planning process of part feeder is presented. Especially, a systematic analysis of workpiece parts and part feeders is performed for the design of databases of CAE system.