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This paper proposes an algorithm that relocates actors to appropriate positions in order for them to act as cluster heads (CHs) with minimal movement in a clustered sensor network. The proposed algorithm assigns actors to target positions in the cluster center (CC). The CC is an area where the transmission ranges of a CH and its neighboring sensors are overlapped. The proposed algorithm first computes a CC in a cluster and then designates the closest point from an actor in the CC as a target position. At the target position, a relocated actor establishes direct links with all neighbors of a CH in order to substitute for the CH. The target position is located on the boundary of the CC, whereas the CH position is inside the region. Therefore, the actor reduces the movement distance required to become a CH when it moves to the target position rather than to the CH position. In the simulation, our proposed algorithm is compared with the existing algorithm that places the actor at the CH position. The results of the simulation show that our algorithm reduces the movement distance by 12.7% compared with that of contemporary scheme.

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In this paper, we design and implement the simulator for WAN storage replication model performance evaluation in cloud computing environment. Each cloud of simulator is composed of virtual machine emulator and storage emulator. The virtual machine emulator is composed of read/write ratio module, the read/write sequence combination module, and the read/write request

In this paper, we implement a Hadoop based cluster for cloud computing and evaluate the performance of this cluster based on application characteristics by executing RandomTextWriter, WordCount, and PI applications. A RandomTextWriter creates given amount of random words and stores them in the HDFS(Hadoop Distributed File System). A WordCount reads an input file and determines the frequency of a given word per block unit. PI application induces PI value using the Monte Carlo law. During simulation, we investigate the effect of data block size and the number of replications on the execution time of applications. Through simulation, we have confirmed that the execution time of RandomTextWriter was proportional to the number of replications. However, the execution time of WordCount and PI were not affected by the number of replications. Moreover, the