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Methods for efficient mining of frequent patterns have been studied extensively by many researchers. However, the previously proposed methods still encounter some performance bottlenecks when mining databases with different data characteristics, such as dense vs. sparse, long vs. short patterns, memory-based vs. disk-based, etc. In this study, we propose a(More)
In this paper, we propose a TDMA slot assignment protocol to improve the channel utilization, which controls the excessive increase of unassigned slots by changing the frame length dynamically. Our proposed protocol assigns one of the unassigned slots to a node which joins the network. If there is no unassigned slots available, our proposed protocol(More)
Wikipedia, a huge scale Web based encyclopedia, attracts great attention as an invaluable corpus for knowledge extraction because it has various impressive characteristics such as a huge number of articles, live updates, a dense link structure, brief anchor texts and URL identification for concepts. We have already proved that we can use Wikipedia to(More)
Photo sharing is one of the most popular Web services. Photo sharing sites provide functions to add tags and geo-tags to photos to make photo organization easy. Considering that people take photos to record something that attracts them, geo-tagged photos are a rich data source that reflects people's memorable events associated with locations. In this paper,(More)
To improve data accessibility in ad hoc networks, in our previous work we proposed three methods of replicating data items by considering the data access frequencies from mobile nodes to each data item and the network topology. In this paper, we extend our previously proposed methods to consider the correlation among data items. Under these extended(More)
Due to its ability to provide collision-free packet transmission regardless of the traffic load, TDMA (Time Division Multiple Access) has been applied in ad hoc sensor networks. We have previously proposed a TDMA slot assignment protocol that utilizes the channel bandwidth effectively in ad hoc sensor networks. However, in this protocol, the channel(More)
Wikipedia, a collaborative Wiki-based encyclopedia, has become a huge phenomenon among Internet users. It covers a huge number of concepts of various fields such as Arts, Geography, History, Science, Sports and Games. As a corpus for knowledge extraction, Wikipedia's impressive characteristics are not limited to the scale, but also include the dense link(More)
In wireless sensor networks (WSNs), many applications require sensor nodes to obtain their locations. Now, the main idea in most existing localization algorithms has been that a mobile anchor node (e.g., global positioning system-equipped nodes) broadcasts its coordinates to help other unknown nodes to localize themselves while moving according to a(More)