• Journal of the Korean Society for Precision Engineering
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• v.16 no.1 s.94
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• pp.161-166
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• 1999

Virtual Manufacturing System(VMS) is a computer model that represents the precise and whole structure of manufacturing systems and simulates their physical and logical behavior in operation. In this paper, a real time simulation for the virtual factory is proposed to integrate a process planning with scheduling under distributed environments. In order to communicate the information under distributed environments, we use a server/client concept using socket program and internet.

• Journal of the Korean Operations Research and Management Science Society
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• v.26 no.2
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• pp.1-11
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• 2001

This paper considers the scheduling of cell-based handoffs to balance the traffic in a fiber-optic microcelluar system. In the system depending on the order of cell based handoff, periodical balancing of the traffic among microcells can be achieved. The cell based handoff problem is formulated as a dynamic programming and the computational complexity is analyzed. Since the scheduling problem requires real time solution, heuristic algorithms are proposed and the computational results are discussed.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.85-88
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• 2002

Maintaining a proper level of cell lead, system throughput can be maximized by a transmission rate control over the uplink in DS/CDMA cellular system to support integrated services of real-time and delay-tolerant traffic. We find that the cell load-based rate control scheme can be further enhanced by taking the varying channel condition into account In conjunction with some fair scheduling algorithm. Our simulation results show that the proposed scheme outperforms the original cell load-based rate control with the round-robin sharing scheduling scheme.

• Journal of Korea Multimedia Society
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• v.4 no.5
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• pp.371-376
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• 2001

Since continuous media such as video and audio data are displayed within a certain time constraint, their computation and manipulation should be handled under limited condition. Traditional real-time scheduling algorithms cold be directly applicable, because they are not suitable for multimedia scheduling applications which support many clients at the same time. Rate Regulating Proportional Share Scheduling Algorithm based on the stride scheduler is a scheduling algorithm considered the time constraint of the continuous media. The stride schedulers, which are designed to general tasks, guarantee the fairness of resource allocation and predictability. The key concept of RRPSSA is a rate regulator which prevents tasks from receiving more resource than its share in a given period. But this algorithm loses fairness which is a strong point of the stride schedulers, and does not show graceful degradation of performance under overloaded situation. This paper proposes a new modified algorithm, namely Modified Proportional Share Scheduling Algorithm considering the characteristics of multimedia data such as its continuity and time dependency. Proposed scheduling algorithm shows graceful degradation of performance in overloaded situation and it reduces the scheduling violations up to 70% by maintaining the fair resource allocation. The number of context switching is 8% less than RRPSSA and the overall performance is increased.

• Journal of Internet Computing and Services
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• v.3 no.2
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• pp.15-26
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• 2002

Since multimedia data such as video and audio data are displayed within a certain time constraint, their computation and manipulation should be handled under limited condition. Traditional real-time scheduling algorithms could net be directly applicable, because they are not suitable for multimedia scheduling applications which support many clients at the same time. Rate Regulating Proportional Share Scheduling Algorithm is a scheduling algorithm considered the time constraint of the multimedia data. This scheduling algorithm uses a rate regulator which prevents tasks from receiving more resource than its share in a given period. But this algorithm loses fairness, and does not show graceful degradation of performance under overloaded situation, This paper proposes a new modified algorithm. namely Modified Proportional Share Scheduling Algorithm considering the characteristics of multimedia data such as its continuity and time dependency, Proposed scheduling algorithm shows graceful degradation of performance in overloaded situation and the reduction in the number of context switching, Furthermore, a new evaluation method is proposed which can evaluate the flexibility of scheduling algorithm.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.2
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• pp.1-7
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• 2002

Since multimedia data such as video and audio data are displayed within a certain time constraint, their computation and manipulation should be handled under limited condition. Traditional real-time scheduling algorithms could not be directly applicable, because they are not suitable for multimedia scheduling applications which support many clients at the same time. Rate Regulating Proportional Share Scheduling Algorithm is a scheduling algorithm considered the time constraint of the multimedia data. This scheduling algorithm uses a rate regulator which prevents tasks from receiving more resource than its share in a given period. But this algorithm loses fairness, and does not show graceful degradation of performance under overloaded situation. This paper proposes a new modified algorithm, namely Modified Proportional Share Scheduling Algorithm considering the characteristics of multimedia data such as its continuity and time dependency. Proposed scheduling algorithm shows graceful degradation of performance in overloaded situation and the reduction in the number of context switching. Furthermore, a new evaluation method is proposed which can evaluate the flexibility of scheduling algorithm.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.1
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• pp.29-35
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• 2004

Locomotive scheduling in railway systems experiences many difficulties because of the complex interrelations among resources, knowledge and various constraints. Artificial intelligence technology has been applied to solve these scheduling problems. These technologies have proved to be efficient in representing knowledge and rules for complex scheduling problems. In this paper, we have applied the CSP (Constraints Satisfaction Problems) programming technique, one of the AI techniques, to solve the problems associated with locomotive scheduling. This method is more effective at solving complex scheduling problems than available mathematical programming techniques. The advanced locomotive scheduling system using the CSP programming technique is realized based on the actual timetable of the Saemaul type train on the Kyong-bu line. In this paper, an overview of the CSP programming technique is described, the modeling of domain and constraints is represented and the experimental results are compared with the real-world existing schedule. It is verified that the scheduling results by CSP programming are superior to existing scheduling performed by human experts. The executing time for locomotive scheduling is remarkably reduced to within several decade seconds, something requiring several days in the case of locomotive scheduling by human experts.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.85-88
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• 1997

Fieldbus is the real-time communication network for process control and manufacturing automation systems. IEC/ISA fieldbus was proposed as an international standard of fieldbus network. This protocol is operated on the basis of token-passing and scheduling mechanism. In this paper, we analyze the performance characteristics of the 1996 version of IEC/ISA fieldbus systems.

• Proceedings of the IEEK Conference
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• 2000.06c
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• pp.121-124
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• 2000

Goal of this Paper is to design and develop core kernel components f3r single processor real-time system, which include real-time schedulers, synchronization mechanism, IPC, message passing, and clock & timer. The goal also contains the basic researches on dynamic load balancing and scheduling which provide mechanism for the distributed information processing and efficient resource sharing among various information appliances based on network.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.158-163
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• 1986

This article surveys techniques and issues related to real time process control system developed for industrial control applications. It covers the system architecture and software engineering issues such as the design of data structures, scheduling of asynchronous task activities, management of shared resources, handling of interrupt and implementing an user friendly man-machine interface. Also problems associated with implementing a real-time system that supports dynamic configuration of data base is addressed.