• Journal of Korean Society of Industrial and Systems Engineering
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• v.45 no.3
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• pp.40-48
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• 2022

An automated material handling system (AMHS) has been emerging as an important factor in the semiconductor wafer manufacturing industry. In general, an automated guided vehicle (AGV) in the Fab's AMHS travels hundreds of miles on guided paths to transport a lot through hundreds of operations. The AMHS aims to transfer wafers while ensuring a short delivery time and high operational reliability. Many linear and analytic approaches have evaluated and improved the performance of the AMHS under a deterministic environment. However, the analytic approaches cannot consider a non-linear, non-convex, and black-box performance measurement of the AMHS owing to the AMHS's complexity and uncertainty. Unexpected vehicle congestion increases the delivery time and deteriorates the Fab's production efficiency. In this study, we propose a Q-Learning based dynamic routing algorithm considering vehicle congestion to reduce the delivery time. The proposed algorithm captures time-variant vehicle traffic and decreases vehicle congestion. Through simulation experiments, we confirm that the proposed algorithm finds an efficient path for the vehicles compared to benchmark algorithms with a reduced mean and decreased standard deviation of the delivery time in the Fab's AMHS.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.56.1-56
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• 2002

$\textbullet$ Introduction $\textbullet$ Constitution and equipment of AMHS $\textbullet$ Discussion about Using Stocker $\textbullet$ Ahead developed 300mm stockers $\textbullet$ 300mm Stocker Solution-Modular Stocker $\textbullet$ Conclusion

• Journal of the Semiconductor & Display Technology
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• v.10 no.1
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• pp.75-81
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• 2011

Today, FPD manufactures are eager to develop larger and larger glass to become the prime market leader. To follow this need, larger AMHS(Automated Material Handling System) development is essential. The radical increase of glass/cassette weight puts a lot of pressure on stocker robot's dual arms, which can cause a damage of expensive glasses and contaminate a clean room facility. In this paper the axiomatic design method is used to institute a design guideline to evenly distribute a pressure throughout the stocker robot structure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.477-478
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• 2011

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.3
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• pp.120-128
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• 2018

OLED Display fabrication system is one of the most complicated discrete processing systems in the world. As the glass size grows from $550{\times}650mm$ to $1,500{\times}1,850mm$ in recent years, the efficiency of Automated Material Handling System (AMHS) has become very important and OLED glass manufacturers are trying to improve the overall efficiency of AMHS. Aiming to meet the demand for high efficiency of transportation, various kind of approaches have been applied for improving dispatching rules and facility layout, while simultaneously considering the system parameters such as glass cassettes due date, waiting time, and stocker buffer status. However, these works did not suggest the operational policy and conditions of distribution systems, especially for handling unnecessary material flows such as detour. Based on this motivation, in this paper, we proposed an efficient algorithm for improving detour transportation in OLED FAB. Specifically, we considered an OLED FAB simplifying OLED production environment in a Korean company, where four stockers are constructed for the delivery of Lot in a bay and linked to processing equipments. We developed a simulation model using Automod and performed a numerical experiment using real operational data to test the performance of three operation policies under considerations. We showed that a competitive policy for assigning alternative stocker in case of detour was superior to the current dedicated policy using a specified stocker and other considered policies.

• Korean Management Science Review
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• v.29 no.1
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• pp.131-141
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• 2012

The automated material handling systems today are playing ever more important roles in semiconductor/LCD fabrication facilities. Recently they became more flexible, intelligent, and speedy than in the past. The facilities have been fully automated because the size and weight of the unit loads used in the facilities were being increased beyond the limits that a human operator can handle. This research develops an efficient procedure to streamline the delivery of unit loads by the automated material handling system (AMHS). For this task, the research employs the event scheduling theory that has been successfully used in the both academia and industry. The developed procedure was applied to an actual LCD fabrication facility and improved the performance of an existing material handling system.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.525-528
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• 2006

This paper considers the vehicle dispatching problem in the automated material handling system (AMHS) of a large scale semiconductor fabrication line, which consists of 18 bays, 468 equipments and uses more than 130 overhead hoist transporters (OHT). We propose an assignment problem based vehicle dispatching approach to take advantage of simultaneous vehicle reassignment based on up-to-date system status. The proposed approach compares fsvorably with the shortest travel distance first rule and with the reassignment based rule which was recently proposed by the authors, in the number of vehicles required and the average lead time.

• Journal of the Korea Society for Simulation
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• v.21 no.2
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• pp.41-50
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• 2012

In this study we first explain details of the semiconductor manufacturing processes and cluster tools. Then we discuss the problems in current fab layout and cluster tool architecture. As a solution to these problems, we propose the ILE (In-Line EFEM) architecture in which wafer movements are conducted through interconnected EFEMs (Equipment Front End Modules) instead of AMHS (Automated Material Handling System). Then we model the pilot ILE system using discrete event simulation and analyze the cycle time. Finally we compare three different scenarios of equipment layout in the ILE system in terms of cycle time.

• Journal of Digital Convergence
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• v.3 no.2
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• pp.9-22
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• 2005

A large scale automated material handling system (AMHS) is simulated using real industrial input data to analyze its performance so that one can scrutinize the critical factors that affect the AS /RS performance. The factors included in this study are line balancing efficiency, the distance between machines, and cycle time of the machines. The performance of AS /RS is measured in terms of R/M utilities that are latter used to classify the AS/RS structure into three types such as Good, Normal, and Poor. Among the three factors considered in this study, the line balance efficiency within each AS/RS is found as the most critical factor which statistically affect the AS/RS performance.

• 한국디지털정책학회:학술대회논문집
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• 2005.11a
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• pp.411-424
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• 2005

A large scale automated material handling system (AMHS) is simulated using real industrial input data to analyze its performance so that one can scrutinize the critical factors that affect the AS/RS performance. The factors included in this study are line balancing efficiency, the distance between machines, and cycle time of the machines. The performance of AS/RS is measured in terms of R/M utilities that are latter used to classify the AS/RS structure into three types such as Good, Normal, and Poor. Among the three factors considered in this study, the line balance efficiency within each AS/RS is found as the most critical factor which statistically affect the AS/RS performance.