• Journal of Institute of Control, Robotics and Systems
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• v.5 no.5
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• pp.600-613
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• 1999

This paper focuses on development of a performance manager for IEEE 802.4 token bus networks to serve large-scale integrated systems. In order to construct the management algorithm, the principles of fuzzy logic, genetic algorithm, and neural network have been combined to represent human knowledge and to imitate of human inference mechanism. Through the simulation experiments, it is shown that the proposed performance manager is capable of improving the network performance without a priori knowledge.

• International Journal of Control, Automation, and Systems
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• v.5 no.5
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• pp.584-593
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• 2007

BACnet is a standard data communication protocol especially designed for building automation and control networks. BACnet uses the Master-Slave/Token-Passing (MS/TP) protocol as one of its field-level networks. In this study, the performance of the BACnet MS/TP protocol is evaluated using an experimental model. The network performance is investigated and evaluated in terms of token rotation time and round trip time. The experimental results show that the performance of the MS/TP network is heavily influenced by the network traffic load, the assignment of MS/TP node address and the network configuration parameter called $N_{max_info-frames}$. Based on the experimental results, simple practical designing guidelines for BACnet MS/TP network systems are also proposed.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.126-129
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• 1998

In order to control the flow of traffics in ATM networks and optimize the usage of network resources, an efficient control mechanism is necessary to cope with congestion and prevent the degradation of network performance caused by congestion. This paper proposes a new UPC(Usage Parameter Control) mechanism that varies the token generation rate and the buffer threshold of leaky bucket by using a Neural Network controller observing input buffers and token pools, thus achieving the improvement of performance. Simulation results show that the proposed adaptive algorithm uses of network resources efficiently and satisfies QoS for the various kinds of traffics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.516-520
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• 1996

This paper focues on development of a timer selection algorithm for IEEE802.4 token bus networks to serve large-scale integrated manufacturing systems. Such factory automation networks have to satisfy delay constraints imposed on time-critical messages while maintaining as much network capacity as possible for non-time-critical messages. Therefore, the object of this paper is to develop timer selection algorithm to minimize a certain penalty function. This paper presents an algorithm based on Genetic Algorithm. The efficacy of the algorithm has been demonstrated by a series of simulation experiments.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.6
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• pp.734-743
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• 1999

In this paper, a real-time communication method using a PICNET-NP(Plant instrumentation and Control Network for Nuclear Power plant) is proposed with an analysis of the control network requirements of DCS(Distributed Control System) in nuclear power plants. The method satisfies deadline in case of worst data traffics by considering aperiodic and periodic real-time data and others. In addition, the method was used to analyze the data characteristics of the DCS in existing nuclear power plant. The result shows that use of this method meets the response time requirement(100ms).

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.12
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• pp.1055-1064
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• 2003

In many automated systems, such as manufacturing systems and process plants, a fieldbus is a very important component for the exchange of various and sometimes crucial information. Some of the information has a tendency to rapidly lose its value as time elapses after its creation. Such information or data is called real-time data that includes sensor values and control commands. In order to deliver these data in time, the fieldbus network should be tailored to have short delay with respect to the individual time limit of various data. Fine-tuning the network for a given traffic requires the knowledge on the relationship between the protocol parameters such as timer values and the performance measure such as network delay. This paper presents a mathematical performance model to calculate communication delays of the Profibus-FMS network when the timer value and the traffic characteristics are given.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1735-1740
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• 2007

Communication network in KTX (Korea Train eXpress), the express train system, has to transmit status variables periodically within tens of seconds and real-time control informations which has short reply like status transition or alarm. KTX uses $Tornad^*$ (TOken Ring Network Alsthom Device) network for this purpose. This network can send and receive messages which enable express train applications embedded in intelligence boards to communicate by itself. Layer 1, 2 of $Tornad^*$ is implemented with differential manchester encoding and IEEE 802.4 standard(token bus standard) respectively. To implement layer 1 and 2, we implemented twisted pair modem using FPGA for layer 1 and used MC68824 from Motorola for layer 2. MC68824 bus arbitration and memory controller is implemented using CPLD.

• International Journal of Contents
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• v.8 no.4
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• pp.1-6
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• 2012

Mutual Exclusion is one of the most studied topics in distributed systems where processes communicate by asynchronous message passing. It is often necessary for multiple processes at different sites to access a shared resource or data called a critical section (CS) in distributed systems. A number of algorithms have been proposed to solve the mutual exclusion problem in distributed systems. In this paper, we propose the new algorithm which is modified from Garg's algorithm[1] thus works properly in a fault-tolerant system. In our algorithm, after electing the token generator, the elected process generates a new token based on the information of the myreqlist which is kept by every process and the reqdone which is received during election. Consequently, proposed algorithm tolerates any number of process failures and also does even when only one process is alive.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1991.10a
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• pp.174-178
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• 1991

ATM, the core technology of BISDN, provides a high degree of flexibility with regard to varying bandwidth requirements for different services. In ATM networks, since users may exceed the traffic volume negotiated at the call setup, traffic from users may need to be monitored and enforced to comply with traffic parameters. The leakybucket mechanism is one of the typical traffic enforcement methods based on the use of transmission tokens for each cell. In this mechanism the major system parameters are size of input buffer, size of token pool, and token generation ratio. In order to represent ATM cell arrivals we assume a Poisson process. In this paper, a state transition analysis technique is used to study the cell loss rates for various values of system parameters.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.426-429
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• 2002

The data link layer (DLL) of Foundation Fieldbus (FF) includes both token-passing and scheduling services. Periodic data are transmitted via the scheduling service, while time-critical and time-available data are transmitted via the token-passing service. This study developed a network interface board that implements the DLL of FF. Using the network interface board, this study experimentally evaluates the delay performance of the DLL of FF. This study measured the delay performance with respect to the change of the DLL parameters of FF, and investigated the relationship between the DLL parameters and network performance. The study also compared the experimental results with the results obtained from an analytical model.