• IE interfaces
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• v.6 no.2
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• pp.53-65
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• 1993

This paper deals with the development of a software module for production planning and scheduling activities of an existing Flexible Machining and Assembly System (FMAS). The Production Planning Module uses the hierarchical and sequential scheme based on "divide and conquer" philosophy. In this module, routes are determined based on the production order, orders are screened, tools are allocated, and order adjustments are executed according to the allocated tools. The Scheduling Module allocates the resources, determines the task priority and the start and completion times of tasks. Re-scheduling can be done to handle unforeseen situations such as lumpy demands and machine breakdowns. Since all modules are integrated with a central database and they interface independently, it is easy to append new modules or update the existing modules. The result of this study is used for operating the real FMAS consisting of a machining cell with 2 domestic NC machines and a part feeding robot, an assembly cell with a conveyor and 3 robots, an inspection cell, an AGV, an AS/RS, and a central control computer.

• Journal of Computational Design and Engineering
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• v.2 no.2
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• pp.105-112
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• 2015

Product Lifecycle Management (PLM) ranges from design concepts of products to disposal. In this paper, we focus on the production planning phase in PLM, which is related to process planning and production scheduling and so on. In this study, key decisions for the creation of production plans are defined as production-planning attributes. Production-planning attributes correlate complexly in production-planning problems. Traditionally, the production-planning problem splits sub-problems based on experiences, because of the complexity. In addition, the orders in which to solve each sub-problem are determined by priorities between sub-problems. However, such approaches make solution space over-restricted and make it difficult to find a better solution. We have proposed a representation of combinations of alternatives in production-planning attributes by using Zero-Suppressed Binary Decision Diagrams. The ZDD represents only feasible combinations of alternatives that satisfy constraints in the production planning. Moreover, we have developed a solution search method that solves production-planning problems with ZDDs. In this paper, we propose an approach for managing solution candidates by ZDDs' network for addressing larger production-planning problems. The network can be created by linkages of ZDDs that express constraints in individual sub-problems and between sub-problems. The benefit of this approach is that it represents solution space, satisfying whole constraints in the production planning. This case study shows that the validity of the proposed approach.

• Journal of Korean Society for Quality Management
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• v.47 no.4
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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.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.4
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• pp.153-158
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• 2010

This study presents a single machine scheduling algorithm to minimize total cost(lateness cost, earliness cost and failure cost) by controlling machining speed. Generally, production scheduling uses the information of process planning and machining speed is not changed at production scheduling. And failure cost is not consider for scheduling algorithm. Therefore, the purpose of this study is to consider the change of machining speed for efficient production scheduling. And performance criteria for algorithm considers total cost. Especially, failure cost of product by increasing machining speed is considered.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.403-411
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• 2013

Horizontal construction projects such as oil and gas pipeline projects typically involve repetitive-work activities with the same crew and equipment from one end of the project to the other. Repetitive scheduling also known as linear scheduling is known to have superior schedule management capabilities specifically for such horizontal construction projects. This study discusses on expanding the capabilities of repetitive scheduling to account for the variance in production rates and visual representation by developing an automated alignment based linear scheduling program for applying temporal and spatial changes in production rates. The study outlines a framework to apply changes in productions rates when and where they will occur along the horizontal alignment of the project and illustrates the complexity of construction through the time-location chart through a new linear scheduling model, Linear Scheduling Model with Varying Production Rates (LSM_VPR). The program uses empirically derived production rate equations with appropriate variables as an input at the appropriate time and location based on actual 750 mile natural gas liquids pipeline project starting in Wyoming and terminating in the center of Kansas. The study showed that the changes in production rates due to time and location resulted in a close approximation of the actual progress of work as compared to the planned progress and can be modeled for use in predicting future linear construction projects. LSM_VPR allows the scheduler to develop schedule durations based on minimal project information. The model also allows the scheduler to analyze the impact of various routes or start dates for construction and the corresponding impact on the schedule. In addition, the graphical format lets the construction team to visualize the obstacles in the project when and where they occur due to a new feature called the Activity Performance Index (API). This index is used to shade the linear scheduling chart by time and location with the variation in color indicating the variance in predicted production rate from the desired production rate.

• Journal of Korean Institute of Industrial Engineers
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• v.16 no.1
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• pp.123-135
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• 1990

An extensive survey is carried out on the applications of AI (Artificial Intelligence) and ES (Expert System) in mathematical programming and simulation, which are the most frequently used tools in production planning. A scheduling field is also reviewed. The scheduling problem is one of the most attractive area for AI and ES researchers, since any practical algorithmic solution methods are not available. The current practice and difficulty of applying AI and ES to production planning are discussed and future research directions are identified.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.3
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• pp.123-133
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• 2011

The advanced planning and scheduling(APS) is an well known enterprise information system that provides optimal production schedules and supports to complete production on time by solving the complex scheduling problems including capacity and due dates. In this paper, we focused on the improvement of the APS that is already established on a real company. The existing APS had several drawbacks, thus utilization and satisfaction were very low. We performed the focused group interviews and the process analysis and could find that the end users and developers have various objectives and the frequently used functions are different. We applied the analytical hierarchy process(AHP) to converge opinions of them on quantitative data. The results show that it is necessary to enhance visibility, to improve user interfaces and response speed, and to reconcile the real business process and the APS's process.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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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.

• Industrial Engineering and Management Systems
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• v.14 no.4
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• pp.401-412
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• 2015

In this paper, we present a modeling approach to production planning for an actual production line and a heuristic method. We also illustrate the successful implementation of the proposed method on the production line. A heuristic algorithm called the push-back algorithm was designed for a single machine earliness/tardiness production planning with distinct due date. It was developed by combining a minimum slack time rule and shortest processing time rule with a push-back procedure. The results of a numerical experiment on the heuristic's performance are presented in comparison with the results of IBM ILOG CPLEX. The proposed algorithm was applied to an actual case of production planning at Woongjin Chemical, a leading manufacturer of filter products in South Korea. The seven-month execution of our algorithm led to a 24.5% decrease in the company's inventory level, thus demonstrating its practicality and effectiveness.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.4
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• pp.414-424
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• 2008

Disassembly scheduling is the problem of determining the quantity and timing of disassembling used or end-of-life products while satisfying the demand of their parts or components over a given planning horizon. This paper considers the two-level disassembly structure that describes a direct relationship between the used product and its parts or components. To formulate the problem mathematically, we first suggest an integer programming model, and then reformulate it to a dynamic programming model after characterizing properties of optimal solutions. Based on the dynamic programming model, we develop a polynomial exact algorithm and illustrate it with an example problem.