Jae-Woo Chang

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Recently data mining applications require a large amount of high-dimensional data. However, most clustering methods for data miming do not work efficiently for dealing with large, high-dimensional data because of the so-called 'curse of dimensionality'[1] and the limitation of available memory. In this paper, we propose a new cell-based clustering method(More)
Many wireless sensor network (WSN) applications require privacy-preserving aggregation of sensor data during transmission from the source nodes to the sink node. In this paper, we explore several existing privacy-preserving data aggregation (PPDA) protocols for WSNs in order to provide some insights on their current status. For this, we evaluate the PPDA(More)
For wireless sensor networks (WSNs), how to design routing protocols is very important to gather data efficiently so that the life of the network can be prolonged. A usual concept to collect data by a sink node is to transfer data from sensor nodes to the sink node by multi-hop. However, it gives rise to two problems. The first one is that core sensor nodes(More)
Location Based Services (LBSs) have recently attracted much attention due to the advancement of GPS facilitates. In LBS, the private and confidential information of user may disclose to others since LBS need a user’s location. To protect the privacy of users, many cloaking algorithms have been proposed to hide user’s actual location. The(More)
Recent development of wireless communication technologies and the popularity of smart phones are making location-based services (LBS) popular. However, requesting queries to LBS servers with users’ exact locations may threat the privacy of users. Therefore, there have been many researches on generating a cloaked query region for user privacy protection.(More)
Because moving objects usually move on spatial networks, efficient trajectory index structures are required to achieve good retrieval performance on their trajectories. However, there has been little research on trajectory index structures for spatial networks, like FNR-tree and MON-tree. But, because both FNR-tree and MON-tree store the moving object's(More)
In Location-Based Services (LBSs), users send location-based queries to LBS servers along with their exact locations, but the location information of the users can be misused by adversaries. In this regard, there must be a mechanism which can deal with the privacy protection of the users. In this paper, we propose a cloaking method considering both(More)
Recently, cloud computing has been spotlighted as a new paradigm of database management system. In this environment, databases are outsourced and deployed on a service provider in order to reduce cost for data storage and maintenance. However, the service provider might be untrusted so that the two issues of data security, including data confidentiality and(More)
Wireless sensor networks (WSNs) have been broadly studied with advances in ubiquitous computing environment. Because the resource of a sensor node is limited, it is important to use energy-efficient routing protocol in WSNs. The cluster-based routing is an efficient way to reduce energy consumption by decreasing the number of transmitted messages to the(More)