• Journal of applied mathematics & informatics
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• v.9 no.2
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• pp.607-620
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• 2002

In this paper, we consider the updating problems to reconstruct the biconnected-components and to reconstruct the weighted shortest path in response to the topology change of the network. We propose two distributed algorithms. The first algorithm solves the updating problem that reconstructs the biconnected-components after the several processors and links are added and deleted. Its bit complexity is O((n'+a+d)log n'), its message complexity is O(n'+a+d), the ideal time complexity is O(n'), and the space complexity is O(e long n+e' log n'). The second algorithm solves the updating problem that reconstructs the weighted shortest path. Its message complexity and ideal-time complexity are $O(u^2+a+n')$ respectively.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.7
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• pp.3480-3500
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• 2017

Accurate locating for the mobile target remains a challenge in various applications of wireless sensor networks (WSNs). Unfortunately, most of the typical localization algorithms perform well only in the WSN with densely distributed sensor nodes. The non-localizable problem is prone to happening when a target moves into the WSN with sparsely distributed sensor nodes. To solve this problem, we propose a collaborative and predictive localization algorithm (CPLA). The Gaussian mixture model (GMM) is introduced to predict the posterior trajectory for a mobile target by training its prior trajectory. In addition, the collaborative and predictive schemes are designed to solve the non-localizable problems in the two-anchor nodes locating, one-anchor node locating and non-anchor node locating situations. Simulation results prove that the CPLA exhibits higher localization accuracy than other tested predictive localization algorithms either in the WSN with sparsely distributed sensor nodes or in the WSN with densely distributed sensor nodes.

• International Journal of Automotive Technology
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• v.5 no.4
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• pp.269-276
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• 2004

There has been considerable activity in recent years in developing timing analysis algorithms for distributed real-time control systems. However, it is difficult for control engineers to analyze the timing behavior of distributed real-time control systems because the algorithms was developed in a software engineer's position and the calculation of the algorithm is very complex. Therefore, there is a need to develop a timing analysis tool, which can handle the calculation complexity of the timing analysis algorithms in order to help control engineers easily analyze or develop the distributed real-time control systems. In this paper, an interactive timing analysis tool, called RAT (Response-time Analysis Tool), is introduced. RAT can perform the schedulability analysis for development of distributed real-time control systems. The schedulability analysis can verify whether all real-time tasks and messages in a system will be completed by their deadlines in the system design phase. Furthermore, from the viewpoint of end-to-end scheduling, RAT can perform the schedulability analysis for series of tasks and messages in a precedence relationship.

• Journal of the Korea Society of Computer and Information
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• v.11 no.4 s.42
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• pp.69-75
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• 2006

Internet-based distributed computing environment have been developed for advanced science and engineering by sharing large-scale resources. Therefore efficient scheduling algorithms for allocating user job to resources in the Internet-based distributed computing environment are required. Many scheduling algorithms have been proposed. but these algorithms are not suitable for the Internet-based Distributed computing environment. That is the previous scheduling algorithm does not consider peer self-control. In this paper, we propose a Peer Availability Period Prediction Strategy for Internet-based distributed computing environment and show that our Strategy has better performance than other Strategy through extensive simulation.

• The KIPS Transactions:PartC
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• v.12C no.4 s.100
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• pp.525-534
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• 2005

We present several distributed algorithms for localizing nodes of a wireless sensor network. Our algorithms determine locations of nodes based on the connectivity between nodes. The basic idea behind our algorithms is to estimate distances between nearby nodes by counting their common neighbors. We analyze the performance of our algorithms experimentally. The results of experiments show that our algorithms achieve performance improvements upon the existing algorithms

• The Transactions of the Korea Information Processing Society
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• v.6 no.5
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• pp.1203-1211
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• 1999

Checkpointing is the one of fault-tolerant techniques to restore faults and to restart job fast. Checkpointing algorithms in distributed systems have been studied for many years. These algorithms can be classified into synchronous Checkpointing algorithms and asynchronous Checkpoiting algorithms. In this paper, we propose an independent Checkpointing algorithm that has a minimum Checkpointing counts equal to periodic Checkpointing algorithm, and relatively short rollback distance at faulty situation. Checkpointing count is directly related to task completion time in a fault-free situation and short rollback distance is directly related to task completion time in a faulty situation. The proposed algorithm is compared with the previously proposed asynchronous Checkpointing algorithms using simulation. In the simulation, the proposed Checkpointing algorithm produces better results than other algorithms in terms of task completion time in fault-free as well as faulty situations.

• The Transactions of the Korea Information Processing Society
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• v.3 no.2
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• pp.327-338
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• 1996

In this paper, we present a new checkpointing algorithm to preserve the consistency of resources in distributed transaction processing systems, and the error recovery algorithms to recover form the failure. In comparison with the existed algorithms, the checkpointing algorithm proposed in this paper can minimize the interference of the distributed transaction and the stroage cost during checkpointing, and does not need the extra message to make th checkpoint. Also we show that the error recovery algorithms prevent the distributed transaction with a partial fault from spreading the fault, which calls domnio-effect and prevent them from restarting cyclically. And we describe the correctness and the performane of the proposed algorithms.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.3
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• pp.385-396
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• 1999

In the process of structural design for large-scale structures with several thousands of degrees of freedom, a plethora of structural calculations with large amount of data storage are required to obtain the forces and displacements of the members. However, current computational environment with single microprocessor such as a personal computer or a workstation is not capable of generating a high-level of efficiency in structural analysis and design process for large-scale structures. In this paper, a high-performance parallel computing system interconnected by a network of personal computers is proposed for an efficient structural analysis. Two distributed structural analysis algorithms are developed in the form of distributed or parallel preconditioned conjugate gradient (DPCG) method. To enhance the performance of the developed distributed structural analysis algorithms, the number of communications and the size of data to be communicated are minimized. These algorithms are applied to the structural analyses of three large space structures as well as a 144-story tube-in-tube framed structure.

• The KIPS Transactions:PartB
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• v.11B no.7 s.96
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• pp.841-848
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• 2004

Evolutionary a1gorithms are well-suited for multi-objective optimization problems involving several, often conflicting objectives. Pareto-based evolutionary algorithms, in particular, have shown better performance than other multi-objective evolutionary algorithms in comparison. However, generalized evolutionary multi-objective optimization algorithms have a weak point, in which the distribution of solutions are not uni-formly distributed onto Pareto optimal front. In this paper, we propose an evolutionary a1gorithm for multi-objective optimization which uses seed individuals in order to overcome weakness of algorithms Published. Seed individual means a solution which is not located in the crowded region on Pareto front. And the idea of our algorithm uses seed individuals for reproducing individuals for next generation. Thus, proposed a1go-rithm takes advantage of local searching effect because new individuals are produced near the seed individual with high probability, and is able to produce comparatively uniform distributed pareto optimal solutions. Simulation results on five testbed problems show that the proposed algo-rithm could produce uniform distributed solutions onto pareto optimal front, and is able to show better convergence compared to NSGA-II on all testbed problems except multi-modal problem.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9A
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• pp.1395-1404
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• 2000

In this paper, we propose a heuristic wavelength routing algorithm for IP datagrams in WDM (Wavelength-Division Multiplexing) networks which operates in a distributed manner, while most previous works have focused centralized algorithms. We first present an efficient construction method for a loose virtual topology with a connectivity property, which reserves a few wavelength to cope with dynamic traffic demands properly. This connectivity property assures that data from any source node could reach any destination node by hopping one or multiple lightpaths. We then develop a high-speed distributed wavelength routing algorithm adaptive to dynamic traffic demands by using such a loose virtual topology and derive the general bounds on average utilization in the distributed wavelength routing algorithms. Finally, we show that the performance of the proposed algorithms is better than that of the FSP(Fixed Shortest-Path) wavelength routing algorithms through simulation using the NSFNET[1] and a dynamic hot-spot traffic model, and that the algorithms is a good candidate in distributed WDM networks in terms of the blocking performance, the control traffic overhead, and the computation complexity.