Kyoungsoo Bok

Mobile P2P Social Network Using Location and Profile

Recently, some social networks for contents sharing and searching among mobile devices have been proposed. However, since the cost of network management is increased and the data search success rate is low, the existing social networks are not suitable for mobile ad hoc networks. For mobile ad hoc networks, the current location of each mobile node is an important factor, which not only affects the network topology but also affects the success rate of data search and share. In this paper, we design a location based social network over the mobile ad hoc networks. The social relation is established by the similarities among different users. The similarity is measured by considering the current positions and common interests. In order to reduce the management overhead, each node only connects to the nodes that have common interests and nearby positions. The contents search is handled by using the social relationships. And the contents are only shared to the users who are interested in it. Therefore, the search success rate is increased and the rubbish messages in the mobile ad hoc network are reduced. Experiments have shown that our proposed method outperforms the existing methods.

An Efficient Mobile Social Network for Enhancing Contents Sharing over Mobile Ad-hoc Networks

The increasing popularity of social networks improves information sharing among different users. Most existing online social networks involve the client/server architecture where each user needs to access to a server for contents sharing with other users. In this paper, we focus on constructing a mobile peer-to-peer based social network. We propose an efficient mobile social network to facilitate contents sharing over mobile ad hoc networks, in which social communities are built based on the interesting keywords, location histories and the current locations of different users. The users with common interest keywords, similar location histories and nearby current location are recommended as friends and connect directly in the mobile social network. The performance results show that the proposed method outperforms the existing methods in terms of the network management cost and contents search.

An efficient mobile peer to peer architecture in wireless ad hoc network

With the rapid development of wireless communication technologies and mobile devices, the mobile peer to peer (MP2P) network has been emerged. Since the computation ability, bandwidth, storage and the dynamic network topology of mobile devices are limited, directly applying the existing wired P2P method to wireless ad hoc network will result in poor performance. A hierarchical MP2P architecture based on super peers has been proposed to alleviate the problem. However, the management cost of the mobile network topology is still high. In this paper, we propose a hierarchical MP2P architecture using clustering mobile peers. The proposed architecture considers the maximum connection time of connected peers, the hop count with the super peer, and the number of connected peers of the super peer. The connection time between the connected peers can be determined by the location, velocity and communication range of each mobile peer. Therefore, the network topology is relatively stable, the management cost of the network topology is decreased and the success rate of contents search is increased. Experiments have shown that our proposed scheme outperforms the existing schemes.

A continuous reverse skyline query processing method in moving objects environments

Many studies on reverse skyline query processing have been done for various services. The existing reverse skyline query processing methods are based on dynamic skylines. There are no reverse skyline query processing algorithms based on metric spaces for location-based services. The existing methods for processing a reverse skyline query have the limitation of service domains and require the high costs of computation to provide various location-based services. In this paper, we propose a new reverse skyline query processing method that efficiently processes a query over the moving objects. In addition, the proposed method processes a continuous reverse skyline query efficiently. In order to show the superiority of the proposed method, we compare it with the previous reverse skyline query processing method in various environments. As a result, the proposed method achieves better performance than the existing method.

An efficient path nearest neighbor query processing scheme for location based services

A path nearest neighbor (PNN) query finds the closest objects from paths consisting of line segments. The existing method has redundant searches as a problem. In this paper, we propose PNN methods that avoid redundant searches in an index. In order to avoid redundant searches, the proposed methods find the closest objects from a path sequentially and determine whether the next closest object is found. To prove the superiority of the proposed methods, we evaluate their performance.

Positioning sensor nodes and smart devices for multimedia data transmission in wireless sensor and mobile P2P networks

In recent, studies on multimedia data transmission have been progressing in a wireless sensor network that consist of a large number of sensor nodes and a mobile P2P network that consists of a large of number of smart devices such as smart phones and wearable devices. When multimedia data such as image, audio, and video are transmitted, it is important to figure out the positions of a sensor nodes and a smart device in the networks. However, existing positioning schemes do not consider network holes that can occur in real application areas, thereby causing many errors during positioning. In this paper, we propose a new positioning scheme considering holes in wireless sensor and mobile P2P network environments. In the proposed scheme, holes are detected based on neighboring node density when holes exist in a network, and the position of a sensor node or a smart device is estimated by conducting distance correction based on the cumulative number of hole-boundary nodes. Through the proposed scheme, highly accurate sensor positioning can be performed even in circumstances where holes are present over a network. To verify the good performance of the proposed scheme, a performance evaluation is conducted by comparing it with existing schemes. It is shown through experiments that the proposed positioning scheme transmits multimedia data to the destination node without data loss when the holes in the network exist.

Retracted: a data gathering method based on a mobile sink for minimizing the data loss in wireless sensor networks

The sensor nodes near to the fixed sink node suffer from the quickly exhausted energy. For this, many methods have been researched to distribute the energy consumption into all wireless sensor nodes using a mobile sink. Since the mobile sink changes its location in the network continuously, it has limited time to communicate with the sensor nodes and needs the time to move to each sensor node. Therefore, before the mobile sink approaches the sensor node, the node can collect huge data by event occurrence. It causes the memory overflow of the sensor node and then the data loss. We propose a novel data gathering method based on a mobile sink considering the data loss in wireless sensor networks. The proposed scheme actively sends the stored data to the mobile sink by considering the amount of collected data in the cluster header and the mobile patterns of the sink node. By doing so, it minimizes the data loss of each sensor node. To show the superiority, we compare it with the existing scheme. Our experimental results show that our proposed scheme minimizes the data loss and has similar network lifetime over the existing scheme based on a mobile sink.

A Hot-Data Replication Scheme Based on Data Access Patterns for Enhancing Processing Speed of MapReduce

In recently years, with the growth of social media and the development of mobile devices, the data have been significantly increased. Hadoop has been widely utilized as a typical distributed storage and processing framework. The tasks in Mapreduce based on the Hadoop distributed file system are allocated to the map as close as possible by considering the data locality. However, there are data being requested frequently according to the data analysis tasks of Mapreduce. In this paper, we propose a hot-data replication mechanism to improve the processing speed of Mapreduce according to data access patterns. The proposed scheme reduces the task processing time and improves the data locality using the replica optimization algorithm on the high access frequency of hot data. It is shown through performance evaluation that the proposed scheme outperforms the existing scheme in terms of the load of access frequency.

k-Nearest neighbor query processing method based on distance relation pattern

The k-nearest neighbor (k-NN) query is one of the most important query types for location based services (LBS). Various methods have been proposed to efficiently process the k-NN query. However, most of the existing methods suffer from high computation time and larger memory requirement because they unnecessarily access cells to find the nearest cells on a grid index. In this paper, we propose a new efficient method, called Pattern Based k-NN (PB-kNN) to process the k-NN query. The proposed method uses the patterns of the distance relationships among the cells in a grid index. The basic idea is to normalize the distance relationships as certain patterns. Using this approach, PB-kNN significantly improves the overall performance of the query processing. It is shown through various experiments that our proposed method outperforms the existing methods in terms of query processing time and storage overhead.

Efficient Data Management Method for Massive RFID Data

In this paper, we propose an efficient data management scheme for path queries and containment queries which are occurred frequently. The proposed data management scheme considers a change of the containment of products during a transport and supports a path of changed products by representing a path of various containments. Also, the compression utilizing the structure of supply chain reduces the stored data volumes. As a result, our method outperforms the existing methods in terms of storage efficiency and query processing time.