Mooyoung Jung

Enabling technologies of agile manufacturing and its related activities in Korea

Abstract As product life cycle becomes shortened, high product quality becomes necessary for survival, markets become highly diversified and global, and continuous and unexpected change becomes the key factor for success. The need for a method of rapidly and cost-effectively developing products, production facilities and supporting software including design, process planning, shop floor control systems is becoming urgent. The essence of this concept of manufacturing would be characterized by introducing a new term agility or rapidity. When compared with computer integrated manufacturing, agile manufacturing can be defined as the capability of surviving and prospering in a competitive environment of continuous and unpredictable change by reacting quickly and effectively to changing markets, driven by customer-designed products and services. Critical to successfully accomplishing agile manufacturing are a few enabling technologies such as the standard for the exchange of products (STEP), concurrent engineering, virtual manufacturing, component-based heterarchical shop floor control system information and communication infrastructure, etc. This article details key concepts of those enabling technologies and presents various activities related to agile manufacturing under development in Korea, especially an agile manufacturing test-bed at Pohang University of Science and Technology and a prototype of the life cycle engineering study of a product model made in a consumer electronic industry.

Agent-based fractal architecture and modelling for developing distributed manufacturing systems

For their timely response to the rapidly changing manufacturing environment and markets, future manufacturing systems must be flexible, adaptable, and reusable. Recently, bionic (or biological), holonic, and fractal manufacturing systems (FrMS) have been discussed as potential candidates for the next generation of manufacturing systems. This study focuses on the FrMS, which is based on the concept of autonomous cooperating agents referred to as fractals. The major component of the FrMS is a basic fractal unit (BFU). It consists of five functional modules: observing module (observer), analysing module (analyser), resolving and executing module (resolver), organizing module (organizer), and reporting module (reporter). Although the FrMS has many conceptual advantages, the implementation of the system has been known to be difficult. This paper is a preliminary study of the basic components and the architecture with an eye toward the future implementation of FrMS. In order to describe the characteristics of a fractal, this paper presents several models including function models using IDEF0, working models using Petri-net, and static/dynamic models using the unified modelling language (UML).

Manufacturing enterprise collaboration based on a goal-oriented fuzzy trust evaluation model in a virtual enterprise

To cope with the rapidly changing manufacturing environment, enterprise collaboration is getting increasingly more attention than ever before. The virtual enterprise (VE) is a concept that supports temporary alliances of manufacturing enterprises that have various collaboration models, such as extended enterprise, networked enterprise, concurrent enterprise, etc. Selection of trustworthy partners and trust building are important in virtual domains because they have largely been affecting the success of a VE. However, because of its complexity of trust, trust models in the literature are limited in their ability to cope with dynamic and virtual environment. In this paper, we propose a trust evaluation method of supporting enterprise collaboration and maximizing the satisfaction of cooperation. In this context, trust means the goal achievement probability. Trust value of an enterprise can be obtained by a fuzzy inference system whose rule-base is based on the top-level goal of a VE. According to the selectors preference, various rules can be applied to trust evaluation. For further study, the planning and scheduling problems should be considered along with the trust-based partner selection for collaboration among manufacturing enterprises.

Satisfaction assessment of multi-objective schedules using neural fuzzy methodology

In the rapidly changing manufacturing environment and marketplace of today, the selection and evaluation of an appropriate manufacturing policy is a vital issue. However, this is a difficult task for decision-makers because manufacturing objectives are multiple, complex, conflict and often vague. This paper presents a methodology for a satisfaction assessment of multi-objective schedules with results from a scheduling simulator. In addition, a general objective structure appropriate for multi-objective manufacturing scheduling is also proposed for use in satisfaction assessment methodologies. The general objective structure is a hierarchical structure of the scheduling objective that consists of a goal, subgoal and criteria. The assessment methodology was based on a neural network and Technique for Order Performance by Similarity to Ideal Solution (TOPSIS), which is a common technique for multi-attribute decision-making problems. This paper extends TOPSIS by using fuzzy logic to deal with inaccurate and linguistic attributes in the general objective structure and a neural network for the weight calculation of inter-attribute importance.

Self-evolution framework of manufacturing systems based on fractal organization

The turbulent environment of modern times breeds a need to ensure flexibility and responsiveness for manufacturing systems. The conventional manufacturing systems, however, are not suitable for the dynamic environment because of their rigid structure. Thus, it is necessary to establish a novel manufacturing system which is capable of proactively perceiving the environment and of autonomously adapting to the changing environments. The purpose of this paper is to propose a self-evolution framework of manufacturing systems that facilitates continuous and quick adaptation. In a self-evolutionary manufacturing system, each production resource regulates its own goal, responding to the changes in its environment. Moreover, the organizational structure of the production resources is also dynamically transformed into a form suitable to the changed goal and the emerging environment. Especially, the proposed framework adopts fractal organization for its principal control architecture.

MANPro: mobile agent-based negotiation process for distributed intelligent manufacturing

This paper examines negotiation procedures in an agent-based distributed shop floor control system (SFCS). A distributed SFCS is under a heterogeneous environment, which is controlled through negotiations between autonomous agents. The negotiation-based control can be considered as the core of a distributed control paradigm. An efficient information exchanging mechanism and an information model with reasonable structure are indispensable for effective negotiations. This paper proposes a novel negotiation mechanism, called a mobile agent-based negotiation process (MANPro), which applies a mobile agent system to the process of information exchange. Since using mobile agents allows each component to execute asynchronously and autonomously and to adapt dynamically to the execution environment, MANPro may guarantee autonomy of agents. Moreover, it is possible to build a fully distributed and autonomous SFCS by using MANPro. MANPro is based on the agent-based control architecture, which includes a communication architecture and an information architecture. The communication architecture provides the exchanging mechanism of information, defining functional modules to support the mechanism while the information architecture provides the framework for information modelling on negotiation, proposing information models required for introducing the ontology concept.

Flexible process sequencing using Petri net theory

Abstract This paper presents a new methodology for flexible process sequencing using a Petri net based approach. In the proposed approach Petri nets are used as a unified framework for representing both operation planning knowledge and process sequence. In specific, the approach taken comprises: (1) modeling operation selection and sequencing knowledge using a Petri net based approach, (2) representing the flexible sequence of operations using Petri net formalism, and (3) linearizing a flexible process sequence using T-INVARIANT analysis. An illustrative example of HoleMakingProcess has been used to demonstrate the Petri net modeling, the operation selection and sequencing procedure (called state propagation procedure), and the linearization procedure.

Integrated precision inspection system for manufacturing of moulds having CAD defined features

An integrated precision inspection system has been developed for manufacturing moulds having CAD defined features. The techniques of precision measurement are implemented for CAD/CAI integration for moulds having sculptured surfaces with some basic features, such as, holes, slots and bosses. Features to be inspected are chosen in the CAD environment, and inspection planning is performed for each feature. The sampling-point strategies are: uniform distribution, curvature dependent distribution, or hybrid distribution of the two depending on the complexity of the sculptured surface. Line and plane features are divided into subintervals, and the measurement points are distributed at random positions in the subinterval. Prime number subintervals are considered for a circle feature, in order to avoid possible periodic distortion of the measurement features. The measurement path planning is performed considering collision avoidance and coordinate matching between the coordinates. The output of the planning is the machine code for a specific CMM having CNC capability. The machine code is downloaded to a specific CMM, and the measurement results are fed back to the computer. A new algorithm, called MINIMAXSURF, is developed to evaluate the form error precisely for sculptured surfaces. The algorithm considers the radius of the touch probe and evaluates the profile tolerance successfully by removing the unavoidable setup errors. The developed measurement system has been applied to real moulds, demonstrating high performance and accuracy.

Modeling and analysis of project team formation factors in a project-oriented virtual organization (ProVO)

In this era of rapid changes in the project-oriented R&D organizations environment, some are actively pursuing joint research to gain a leading edge over other R&D organizations. The condition for joint research is the knowledge that an organization needs from other organizations and the capability of collaboration. This study presents a ProVO model using the concept of virtual organization and project team formation based on knowledge and collaboration. In this model, VO is represented by the capability of carrying out a project and the cost of employment. Capability consists of knowledge competence (KC) and collaboration competence (CC). KC, in turn, consists of individual knowledge and collective knowledge from social network, while CC consists of density, degree centrality, and closeness centrality. To verify the presented model, we conducted a case study on a research institute. The analysis results show that all five project team formation factors of KC and CC are statistically significant. A prototype was also developed for selecting project team members using the binary logistics regression model. The proposed ProVO model can assist quantitative decision making on the selection of project team members by a project-oriented R&D organization from the aspects of knowledge and collaboration.

Conflict detection and resolution for goal formation in the fractal manufacturing system

The fractal manufacturing system (FrMS) is based on the concept of autonomously cooperating agents referred to as fractals. A fractal is a set of self-similar agents whose goal can be achieved through cooperation, coordination, and negotiation among the agents for themselves. A fractal has fractal-specific characteristics (e.g. self-similarity, self-organization, self-optimization, goal-orientation, and dynamics), and it also has the characteristics of an agent (e.g. autonomy, mobility, intelligence, cooperation, and adaptability) at the same time. In the FrMS, a goal can be regarded as the status which the system aspires to be in. The goal-formation process (GFP) in the FrMS is a process of generating goals and modifying them by coordination between agents. In the GFP, conflicts may occur between goals, which can drive a system to become inefficient. In this paper, a conflict resolution mechanism via agent-based negotiation is proposed for facilitating the GFP. The scheme deals with non-fixed goals. The mobile agent-based negotiation process (MANPro), in which a mobile agent is used for information-exchanging and problem-solving, is used for negotiations in this scheme. The proposed mechanism is illustrated with a goal formation scenario in an exemplary FrMS.