• Journal of Information Processing Systems
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• v.13 no.5
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• pp.1229-1242
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• 2017

In this paper, an interference aware distributed multi-channel MAC (IDMMAC) protocol is proposed for wireless sensor and actor networks (WSANs). The WSAN consists of a huge number of sensors and ample amount of actors. Hence, in the IDMMAC protocol a lightweight channel selection mechanism is proposed to enhance the sensor's lifetime. The IDMMAC protocol divides the beacon interval into two phases (i.e., the ad-hoc traffic indication message (ATIM) window phase and data transmission phase). When a sensor wants to transmit event information to the actor, it negotiates the maximum packet reception ratio (PRR) and the capacity channel in the ATIM window with its 1-hop sensors. The channel negotiation takes place via a control channel. To improve the packet delivery ratio of the IDMMAC protocol, each actor selects a backup cluster head (BCH) from its cluster members. The BCH is elected based on its residual energy and node degree. The BCH selection phase takes place whenever an actor wants to perform actions in the event area or it leaves the cluster to help a neighbor actor. Furthermore, an interference and throughput aware multi-channel MAC protocol is also proposed for actor-actor coordination. An actor selects a minimum interference and maximum throughput channel among the available channels to communicate with the destination actor. The performance of the proposed IDMMAC protocol is analyzed using standard network parameters, such as packet delivery ratio, end-to-end delay, and energy dissipation, in the network. The obtained simulation results indicate that the IDMMAC protocol performs well compared to the existing MAC protocols.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.27-30
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• 2012

In the Cluster-Based Routing Protocol (CBRP) a cluster header in each cluster should be elected. The cluster headers consume energy much more than other nodes because they manage and operate all of mobile nodes in their cluster. The traditional CBRP elects a cluster header without considering the remaining electric energy of each node. So, there exists problems that the cluster header has short average lifetime, and another cluster header should be elected again frequently. In this paper, we propose the improved protocol which prolongs the lifetime of the cluster header, decreases of header re-elected problem, decreases of header re-elected problem and enhances the stability of the path. In order to achieve this, when a cluster header is elected in a cluster, the remaining electric energies of all the nodes are compared with one another, and the node with the highest energy is elected as the cluster header. Also, the node with the second highest energy is elected as the second header. If the elected cluster header is unable to perform the role of the cluster header because the remaining energy level goes low, it sends a beacon message to neighbor member nodes and the second header will serve as the cluster header.

• Journal of the Korea Society of Computer and Information
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• v.18 no.1
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• pp.63-71
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• 2013

In the Cluster-Based Routing Protocol (CBRP) a cluster header in each cluster should be elected. The cluster headers consume energy much more than other member nodes do because they manage and operate all of mobile nodes in their cluster. The traditional CBRP elects a cluster header without considering the remaining electric energy of each node. So, there exist problems that the cluster header has short average lifetime, and a new cluster header should be elected again frequently. In this paper, we propose the improved protocol which prolongs the lifetime of the cluster header, decreases the problem of re-electing the cluster header and enhances the stability of the path. In order to achieve this, when a cluster header is elected in a cluster, the remaining electric energies of all the nodes are compared with one another, and the node with the highest energy is elected as the cluster header. Also, the node with the second highest energy is elected as the second header. If the elected cluster header is unable to perform the role of the cluster header any more because the remaining energy level goes low, it sends a beacon message to neighbor member nodes, then the second header will serve as the cluster header.

• Cross-Cultural Studies
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• v.38
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• pp.89-113
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• 2015

This paper explores the work of mourning of 9/11 in the United States, focusing on the project of building the National September 11 Memorial managed by the Lower Manhattan Development Corporation(LMDC) and the War on Terror declared by the George W. Bush administration in the wake of 9/11. This paper first looks at the project of building the Natioanl September 11 Memorial and considers what was at stake in achieving this project. It also examines the limitations of the project. This paper argues that, in spite of the efforts to mourn the victims in significant and meaningful ways, the work of mourning in the memorial project fails at least in two respects. First, the memorial project "began so soon" right after 9/11 that the victims' families were not given enough time to mourn their loved ones. Second, the project were permeated with American nationalism and patriotism, which made the 316 non-American victims of 9/11 invisible and forgotten. Then, it goes on to examine the War on Terror because the War on Terror epitomized the failure of mourning due to these causes. In his address to the nation delivered on the very day of 9/11, President George W. Bush stated that "America was targeted for the attack because we're the brightest beacon for freedom and opportunity in the world" and that the terrorists failed to threaten America into chaos. He also stated that America is in "the war against terrorism." These statements were a futile reassertion of the illusion of American invulnerability and a prohibition of mourning in favor of violent military responses to 9/11. American nationalism also underlies Bush's official naming of September 11 as "Patriot Day." The victims were sacrificed because they were at the site when terrorists attacked, which implies that their death had nothing to do with American patriotism. Naming September 11 as Patriot Day was an act of imbuing the absurdity of the victims' death with a false meaning and an act of forgetting the non-American victims. The failure of the work of mourning of 9/11 consisted in the inability to recognize human vulnerability and interdependence and the inability to mourn not only American victims but also non-American victims killed in 9/11 and the War on Terror. A meaningful and significant mourning could be possible when we realizes that all human beings are exposed to one another and their lives are interdependent on one another. September Eleventh Families for Peaceful Tomorrows well demonstrated this kind of mourning. When most Americans supported violent retaliations, Peaceful Tomorrows made pleas for nonviolent responses to 9/11. Turning their grief into action for peace, its members work "to create a safer and more peaceful world for everyone," not only for Americans. Their effort to mourn in meaningful and nonviolent ways delivers the message that a disaster like 9/11 should not happen anywhere.