• The Transactions of the Korea Information Processing Society
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• v.6 no.8
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• pp.2158-2170
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• 1999

It has been required more reliable communication on processes and improvement of system performance as distributed systems using multicast protocol became widespread. In distributed environment maintaining data consistency through asynchronous execution of processes and coordinating the activities of them would occurs. This paper proposes a total ordering algorithm, TORMP, in order to resolve these problems. TORMP takes advantage of multicast protocol and uses an effective token passing method. It reduces a process delaying time before transmitting its message by multicasting a token simultaneously to every process that initiates the request of the message. Moreover, the processes receiving the token start multicasting the message at the same time, which causes to cut down the overall transmission dely. In case that one process sends a message, TORMP hardly uses the procedure of controlling for ordering. It gives fairly the right of sending messages to all processes in a group with utilizing vector clock. In TORMP, unlike other algorithms, the number of packets generated during ordering process does not depend on the number of processes.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.3
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• pp.125-133
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• 2002

In this paper, we present an efficient broadcast protocol, called Btoken, that ensures total ordering of messages and atomicity of delivery in the large scaled distributed systems. Unlike the existing token-passing based protocol, Btoken does not circulate a token around the ring, instead, it uses three kinds of control messages for token transmission. The token has a sequence number field for broadcasting message, and the only site having the token can broadcast a message. When a site wishes to broadcast, It must send a message to the token site requesting the token. The token site sends a message with the token to the requester When the requester receives the token, it becomes the current token site and broadcasts a new message after setting sequence number derived from a field of the token into its message. Upon reception of it, any operating member is informed the position of the token site and will send token requesting message to the new token site. However, the other site may request the token to the old token site prior to receiving the broadcast message from the new token site. To resolve this problem, Btoken uses a message which is sent to the current token site by the old token site notifying who is the next token requester. Results of our simulation of the protocol show that Btoken is more efficient in the large scaled distributed system compared to existing broadcast protocols.

• The Transactions of the Korea Information Processing Society
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• v.7 no.5
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• pp.1426-1433
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• 2000

As distributed computing systems become popular, many modeling techniques and methods have been developed in specify the specification formally and verify the distributed/concurrent sytems. In spite of importance of communication in distributed object-oriented systems, specifying of communication method generally has not been emphasized in the design phase. One reason is due to the system designer misunderstanding, that is, a specification needs to be independent on the implementation. However, since defining communication pattern indistributed object-oriented systems is more serious than the required message passing method in the design phase. specifying the communication pattern is necessary instead of postponing until the implementation. In this paper, two formal specification techniques, temporal logic method and Petri nets method, for the communication in distributed systems are discussed. One is based on the temporal logic, which specifies the different patterns of primitive predicates. This method enable to define the underlying mechanism which can be interpreted as constraints. The Petri net method helps to specify the dynamic behavior of communicational patterns using the properties of Petri nets.

• Atmosphere
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• v.22 no.1
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• pp.109-115
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• 2012

We parallelized the CFD_NIMR model, which is a numerical meteorological model, for best performance on both of distributed and shared memory parallel computers. This hybrid parallelization uses MPI (Message Passing Interface) to apply horizontal 2-dimensional sub-domain out of the 3-dimensional computing domain for distributed memory system, as well as uses OpenMP (Open Multi-Processing) to apply vertical 1-dimensional sub-domain for utilizing advantage of shared memory structure. We validated the parallel model with the original sequential model, and the parallel CFD_NIMR model shows efficient speedup on the distributed and shared memory system.

• 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.

• 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.

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.2
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• pp.150-161
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• 1999

This paper deals with the design and development of a real-time integrated communication architecture for heterarchical SFCS(Shop Floor Control System). In autonomous agent-based heterarchical SFCS, each functional unit of parts and resources is equipped with an intelligent controller (agent) that acts as the representative of the entity. The controllers communicate and negotiate with other controllers on a real-time basis through message passing and bidding protocol to achieve mutual agreements for task sharing. ICPL(Integrated Communication Protocol and Language) is proposed for this purpose. ICPL is a language and a protocol for supporting communication among intelligent controllers. Based on the speech act theory, this paper proposes a semantic description for ICPL that associates the description of the cognitive states of controllers with the use of language primitives (message_type). Semantics for the basic set of ICPL messages is described. Eventually, an ICPL-based communication architecture can provide the implementation of the distributed and heterarchical SFCS, and makes the intelligent controller transparent to the negotiation problem.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.439-446
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• 2001

The main stream of parallel programming today is using synchronous algorithms, where processor synchronization for correct computation and workload balance are essential. Overall performance of the whole system is dependent upon the performance of the slowest processor, if workload is not well-balanced or heterogeneous clusters are used. Asynchronous iteration is a way to mitigate such problems, but most of the works done so far are for shared memory systems. In this paper, we suggest and implement a parallel large sparse linear system solver that improves performance on distributed memory systems like clusters by reducing processor idle times as much as possible by asynchronous iterations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1B
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• pp.59-66
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• 2012

The use of MPSoC has been increasing because of a rise of use of mobile devices and complex applications. For improving the performance of MPSoC, number of processor has been increasing. Standard MPI is used for efficiently sending data in distributed memory architecture that has advantage in multi processor. Standard In this paper, we propose a scalable distributed memory system with a low cost hardware message passing interface(MPI). The proposed architecture improves transfer rate with buffered send for small size packet. Three queues, Ready Queue, Request Queue, and Reservation Queue, work as previous architecture, and two queues, Small Ready Queue and Small Request Queue, are added to send small size packet. When the critical point is set 8 bytes, the proposed architecture takes more than 2 times the performance improvement in the data that below the critical point.

• The KIPS Transactions:PartA
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• v.12A no.6 s.96
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• pp.507-514
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• 2005

This paper presents a partially decentralized passive replication algorithm for deterministic servers in message-passing distributed systems. The algorithm allows any backup server, not necessarily the primary server, to take responsibility for processing its received client request and coordinating with the other replica servers after obtaining the delivery sequence number of the request from the primary. Thanks to thus desirable feature, the algorithm with conventional load balancing techniques can efficiently avoid extreme load conditions on the primary. Therefore, it can provide better scalability of deterministic and replicated sewer systems than traditional passive replication algorithms. Simulation results indicate that the proposed algorithm can reduce $16.5\%{\~}52.3\%$ of the average response time of a client request compared with the traditional ones.