• 제어로봇시스템학회논문지
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• 제5권6호
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• pp.724-733
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• 1999

An effective method of system modeling and dynamic scheduling for the back-end line of semiconductor manufacturing is proposed. The virtual factory, describing semiconductor manufacturing line, is designed in detail, and then a Petri net model simulator is developed for operation and control of the modular cells of the virtual factory. The petri net model is a colored timed Petri nets (CTPNs). The simulator will be utilized to analyze and evaluate various dynamic status and operatons of manufacturing environments. The dynamic schedulaer has a hierarchical structure with the higher for planning level and the lower for dynamic scheduling level. The genetic algorithm is applied to extract optimal conditions of the scheduling algorithm. The proposed dynamic scheduling is able to realize the semiconductor manufacturing environments for the diversity of products, the variety of orders by many customers, the flexibility of order change by changing market conditions, the complexity of manufacturing processes, and the uncertainty of manufacturing resources. The proposed method of dynamic scheduling is more effective and useful in dealing with such recent pressing requirements including on-time delivery, quick response, and flexibility.

• 대한산업공학회지
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• 제42권6호
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• pp.404-411
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• 2016

In footwear manufacturing systems, the upper parts of the shoes are manually sewed on a sub-line while bottom parts are produced by machines such as injection and molding machines on a sub-line before these two parts are combined into complete shoes on a final assembly line. The manual operations for the upper parts lead to a large variability in processing times, resulting in higher work-in-process inventory. In most footwear industries, production lines have been controlled by MRP-based push systems. Some industries attempt to introduce Kanban-based pull systems. This paper identifies the characteristics of the footwear manufacturing processes, and discusses the problems of the current control systems. As an operational alternative, a CONWIP-based control strategy is presented. Simulation experiments are performed to examine the performance of the control strategies.

• Journal of applied mathematics & informatics
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• 제33권1_2호
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• pp.77-87
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• 2015

Parallel lines are often used to increase production rate in many manufacturing systems where the main line splits into several lines in parallel, and after some operations, they merge into a main line again. Queueing networks with finite buffers have been widely used for modeling and analyzing manufacturing systems. This paper provides an approximation technique for multi-server two-stage networks with merge configuration and blocking which will be a building block for analysis of general manufacturing systems with parallel lines and merge configuration. The main idea of the method is to decompose the original system into subsystems that have two service stations with multiple servers, two buffers and external arrivals to the second stage are allowed. The subsystems are modeled by level dependent quasi-birth-and-death (LDQBD) process.

• International Journal of Korean Welding Society
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• 제3권1호
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• pp.2-7
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• 2003

Laser welding application for car body manufacturing has many advantages in the stiffness and the lightness of vehicle, the productivity of assembly line, and the degree of freedom in design. This presentation will express the innovation of car body manufacturing including parameter optimization, process modeling, and system integration. In this application the investment for systems was cut down dramatically by real time switching over the laser path between two welding stations. Points of technical discussion are as follows; optimization of parameters such as laser power, robot speed and trajectory, compact and useful design of jig & fixture to assure welding quality for 3 sheet-layer zinc-coated steel, system integration between 4㎾ Nd:YAG laser device and the other systems, on-line real time welding quality monitoring system, perfect safety standards for high power laser, minimization of consumption costs such as arc lamp, protective glass for optic, etc. This application was successfully launched mass production line in 2001. The laser-welded line of side panel consists of 122 stitches totally. And the length is about 2.4m.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.915-916
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• 2008

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.141-143
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• 2002

Litrex Ink Jet equipment offers prospect for reliable and low cost manufacturing process for PLED technology. The design concept of 140P system that we are developing meets requirement of process/equipment for PLED manufacturing line in terms of higher mechanical accuracy, in-line monitoring system of print head, high precision of process capability, reasonable through-put, high reliability/easier maintenance and no particle generation.

• 대한전기학회논문지
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• 제43권4호
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• pp.658-665
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• 1994

CIM is generally considered as a solution for total automation of a manufacturing system. In a CIM system, Flexible Manufacturing System(FMS) is linked colsely to the actual manufacturing line. This study will examine the strategy of integrating incompatible FA equipments, expecially PLCs (Programable Logic Controllers). PLC Manager is proposed as a model for integrating PLC algorithms, whose primary tasks are to communicate line-field data with PLCs and cell controller. To operate it, a PLC script language is designed and implemented.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1999년도 추계학술대회 논문집
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• pp.224-228
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• 1999

When we construct a manufacturing plant, optimal design is very important. This paper is to simulate an engine manufacturing flow line for commercial vehicle. The parameters we consider in simulation include facility downtime, tool change time, buffer size between consecutive stations, and time to repair the facility. We use AutoMod to compare the alternatives. The objective is to minimize the total cost. Simulation results provide significant cost saving by improving the current design and policy.

• Industrial Engineering and Management Systems
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• 제3권1호
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• pp.52-58
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• 2004

This report examines the issue of designing an efficient production system by increasing several types of flexibility. Increasing manufacturing flexibility is a key strategy for efficiently improving market responsiveness in the face of uncertain market demand for final products. The manufacturing system comprises multiple plants, of which individual plants have multiple manufacturing lines that are designed to produce limited types of products in accordance with their size and materials. Imbalance in the workload occurs among plants as well as among manufacturing lines because of fluctuations in market demand for final products. Thereby, idleness of some manufacturing lines and longer lead times in some manufacturing lines occur as a result of the high workload. We clarify how these types of flexibility affect manufacturing performance by improving only one type of flexibility or by improving multiple types of flexibility simultaneously. The average lead time and the imbalance in workload are adopted as measures of manufacturing performance. Three types of manufacturing flexibility are interrelated: machine flexibility, routing flexibility, and process flexibility. Machine flexibility refers to the various types of operations that a machine can perform without requiring the prohibitive effort of switching from one order to another. Routing flexibility is the capability of processing a given set of part types using more than one line (alternative line) in the plant. Process flexibility results from being able to build different types of final products at the same plant.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2002년도 추계학술대회 논문집
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• pp.115-121
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• 2002

The growth of semiconductor industry attracted to researchers like design, facility technique and making small size chip areas. But nowadays, cause of technology extension and oversupply and price down, yield improvement is the most important point on growth. This paper describes the computer mode]ing technique as the solutions to analyze the problem, to formalize the semiconductor manufacturing process and to build advanced manufacturing environments. The computer models are built referring an existing 8' wafer production line in Korea.