Visualization system to identify structurally vulnerable links in OHT railway network in semiconductor FAB using...

Area of Science:

• Industrial Engineering
• Computer Science
• Operations Research

Background:

• Semiconductor fabrication relies on automated guided vehicles (AGVs) like Overhead Hoist Transports (OHTs) for wafer transport.
• Existing routing algorithms (e.g., Dijkstra's) can cause congestion and deadlocks in complex OHT networks.
• Identifying structurally vulnerable links is crucial for optimizing FAB productivity.

Purpose of the Study:

• To identify structurally vulnerable links in Overhead Hoist Transport (OHT) railway networks within semiconductor fabrication (FAB).
• To develop a modified betweenness centrality algorithm accounting for the hierarchical node-port structure of OHT networks.
• To create a web-based visualization system for enhanced on-site decision-making regarding network vulnerabilities.

Main Methods:

• Employed betweenness centrality to quantify structural vulnerability of the OHT network.
• Modified the Brandes algorithm to incorporate node-port characteristics without increasing computation time.
• Integrated parallelization into the modified algorithm to further reduce computation time.
• Developed an end-to-end web-based visualization system for calculating and displaying centrality results.

Main Results:

• Developed a novel betweenness centrality algorithm tailored for OHT networks with node-port structures.
• Created a functional web-based visualization system for identifying vulnerable links.
• Validated the algorithm's effectiveness by comparing results with historically identified vulnerable links from industry partners.
• Demonstrated that the node-port structure betweenness centrality accurately identifies critical network choke points.

Conclusions:

• The modified betweenness centrality algorithm effectively identifies vulnerable links in semiconductor FAB OHT networks.
• The visualization system significantly enhances the practical applicability and relevance of identifying network vulnerabilities.
• Optimizing OHT network structure based on identified vulnerabilities can improve FAB productivity and reduce deadlocks.