• IE interfaces
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• 제20권3호
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• pp.277-287
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• 2007

Semiconductor manufacturing is one of the most complex and capital-intensive processes composed of several hundreds of operations. In today’s competitive business environments, it is more important than ever before to manage manufacturing process effectively to achieve better performances in terms of customer satisfaction and productivity than those of competitors. So, many semiconductor manufacturing companies implement advanced planning and scheduling (APS) system as a management tool for the complex semiconductor manufacturing process. In this study, we explain roles of production planning and scheduling in semiconductor manufacturing and principal factors that make the production planning and scheduling more difficult. We describe the APS system implementation project at Korean semiconductor manufacturing company in terms of key issues with realistic samples.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제4권3호
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• pp.252-256
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• 2003

This paper deals with a case study on the development of computerized scheduling system for core products. We propose a heuristic algorithm which is based on the sequencing rules and the allocation rules to satisfy the due date for each product, and develop a scheduling system for the manufacturer of core products. The system operates under a client/server circumstance. The important information constitutes a database, and it can be retrieved whenever it is needed. The benefits of the scheduling system are the exclusion of hand operations of data, the reduction of execution time for production planning and the reduction of average inventories.

• Korean Management Science Review
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• 제17권2호
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• pp.67-73
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• 2000

This paper describes a scheduling support system for a plant where the machine environment may be modeled as non-identical parallel machine lines (NPML). That is, there are a number of stages in series with various different-capability-machines at each stage. Arriving continuously are jobs with their specific due dates, processing times and candidate processing machines. We’ve developed a real-time scheduling module in conjunction with a supporting production information system which supplies necessary data to the module. This scheduling module is one of the 9 modules in this system, and is composed of both a scheduling interface and a production monitoring interface. This module allows users to generate many candidate schedules by selecting their business policies. The selective arguments which are available consist of allocation costs, batch sizes and machine selection intervals. They are now being implemented at a powder metallurgy plant.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.473-474
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• 2010

• Journal of Korean Institute of Industrial Engineers
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• 제41권1호
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• pp.1-9
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• 2015

In shipbuling processes, a quay wall is a major resource for additional operations after an erection operation at dock. A quay wall is becoming a new bottleneck instead of docks, while ship types with long operation time at quay wall are increasing recently. We developed a quay wall scheduling algorithm for the quayside operations of ships in this paper. The objective function is to minimize the sum of not assigned days of ships which have to be assigned to any quay wall under limited numbers of quay walls. The scheduling algorithm is based on an assignment method to assign each ship to a quay wall among its alternative quay walls at the time of launching or moving to another quay wall. The scheduling algorithm is also using Tabu Search algorithm to optimize assignment sequence of ships. The experiment shows that the algorithms in this paper are effective to make schedule of the quayside operations of ships.

• Journal of Korean Institute of Industrial Engineers
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• 제32권3호
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• pp.163-171
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• 2006

This paper considers a scheduling problem to minimize the sum of the associated scheduling (production/delivery times) cost and the delivery cost for an integrated system of a single production machine and various transportation vehicles with transportation mode selection allowed. Each transportation mode is provided with a fixed number of vehicles at the associated delivery time and cost. The proposed problem is characterized as being NP-hard. Some solution properties are also characterized. Therewith, three heuristic algorithms (called SPT-based, LWF-based and WSPT-based heuristic) and a branch-and-bound algorithm are derived. In order to evaluate the effectiveness and efficiency of the proposed algorithms, computational experiments are made with some numerical instances.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제39권1호
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• pp.153-161
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• 2016

Semiconductor manufacturing has suffered from the complex process behavior of the technology oriented control in the production line. While the technological processes are in charge of the quality and the yield of the product, the operational management is also critical for the productivity of the manufacturing line. The fabrication line in the semiconductor manufacturing is considered as the most complex part because of various kinds of the equipment, re-entrant process routing and various product devices. The efficiency and the productivity of the fabrication line may give a significant impact on the subsequent processes such as the probe line, the assembly line and final test line. In the management of the re-entrant process such as semiconductor fabrication, it is important to keep balanced fabrication line. The Performance measures in the fabrication line are throughput, cycle time, inventory, shortage, etc. In the fabrication, throughput and cycle time are the conflicting performance measures. It is very difficult to achieve two conflicting goal simultaneously in the manufacturing line. The capacity of equipment is important factor in the production planning and scheduling. The production planning consideration of capacity can make the scheduling more realistic. In this paper, an input and scheduling rule are to achieve the balanced operation in semiconductor fabrication line through equipment capacity and workload are proposed and evaluated. New backward projection and scheduling rule consideration of facility capacity are suggested. Scheduling wafers on the appropriate facilities are controlled by available capacity, which are determined by the workload in terms of the meet the production target.

• Journal of Korean Society for Quality Management
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• 제47권4호
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• pp.823-835
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• 2019

Purpose: This study deals with a production planning and scheduling problem to minimize the total weighted tardiness on hybrid flow shop with sets of non-identical parallel machines on stages, where parallel machines in the set are dedicated to perform specific subsets of jobs and sequence-dependent setup times are also considered. Methods: A two-stage approach, that applies MILP model in the 1st stage and dispatching rules in the 2nd stage, is proposed in this paper. The MILP model is used to assign jobs to a specific machine in order to equalize the workload of the machines at each stage, while new dispatching rules are proposed and applied to sequence jobs in the queue at each stage. Results: The proposed two-stage approach was implemented by using a commercial MILP solver and a commercial simulation software and a case study was developed based on the spark plug manufacturing process, which is an automotive component, and verified using the company's actual production history. The computational experiment shows that it can reduce the tardiness when used in conjunction with the dispatching rule. Conclusion: This proposed two-stage approach can be used for HFS systems with dedicated machines, which can be evaluated in terms of tardiness and makespan. The method is expected to be used for the aggregated production planning or shop floor-level production scheduling.

• Korean Journal of Computational Design and Engineering
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• 제18권3호
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• pp.224-233
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• 2013

For the scheduling and the job assignment of the ship hull production design which is a process-based work, we suggest the simulation-based scheduling using the discrete-event-based business process simulation. First, we analyze the ship hull production design process from the perspective of a job assignment to make it into the simulation model using DEVS (Discrete Event System Specification) which is the representative modeling method for a discrete-event simulation. Based on the APIs of the open-source discrete-event simulation engine, we implement the simulation using the Groovy script. We develop the scenario generator in which the user defines detail information of the construction drawing and its member blocks, and design engineers information, and the various setting for the simulation including the job assignment strategy. We use the XML files from this scenario generator as inputs of simulation so that we can get simulation result in forms of Gantt chart without changes of the simulation model.

• Journal of Korean Society for Quality Management
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• 제15권2호
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• pp.74-81
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• 1987

The purpose of this paper is to find out the relative priority among the queueing products for next operation. Critical ratio scheduling is a technique for use in production scheduling to establish and maintain relative priority among the jobs. The relative priority is based on a ratio of when the completed job is required and how much time is required to complete it. A numerical example of "D" company is solved. Jobs are classified into 3 categories; the behind scheduling jobs, the on time jobs and the ahead scheduling jobs.