• The KIPS Transactions:PartD
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• v.10D no.4
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• pp.591-602
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• 2003

Delay and discontinuance phenomenon of service are cause by sudden increase of the network communication amount and the quantity consumed of resources when Internet users are driven excessively to a conventional single large database sewer. To solve these problems, spatial database cluster consisted of several single nodes on high-speed network to offer high-performance is risen. But, research about spatial join operation that can reduce the performance of whole system in case process at single node is not achieved. So, in this paper, we propose efficient parallel spatial join processing method in a spatial database cluster system that uses data partitions and replications method that considers the characteristics of space data. Since proposed method does not need the creation step and the assignment step of tasks, and does not occur additional message transmission between cluster nodes that appear in existent parallel spatial join method, it shows performance improvement of 23% than the conventional parallel R-tree spatial join for a shared-nothing architecture about expensive spatial join queries. Also, It can minimize the response time to user because it removes redundant refinement operation at each cluster node.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.9
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• pp.369-380
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• 2013

Recently, role-based distributed system models have been proposed to support adaptive interactions in ubiquitous application environment. A Role-based distributed model regards an application as an organization composed of roles, and separate players running role processes from the roles. When an application is running, it binds a role with a player, and the player runs dynamically assigned role processes provided by an application for supporting adaptability. However, there has not been much attention on researches about development and runtime environment for role-based distributed systems. In this paper we suggest an application framework as an environment for developing and executing role-base distributed systems. The application framework is divided into two parts: an organization framework to manage and construct an organization composed of roles necessary in the application, and a player framework to provide running environment for players. In this paper, we focus on the organization framework which supports the creation and management of organizations, directory service for players and allocation of players to roles, and message brokering between roles and players. The proposed framework makes developers to be able to develop highly adaptive distributed systems in the ubiquitous environment.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.4
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• pp.369-380
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• 2003

With the proliferation of a wireless support and the advances of mobile devices, there is a growing need of making it available for a wireless network as well. Low bandwidth of a wireless network is one of the major issues that should be considered for extending a synchronous collaboration system developed for a wired network to supuort a wireless network. We propose a priority-based view synchronization scheme, exploiting the relaxed synchronization. The proposed scheme leverages the fact that mobile users need not have the exactly same view as the users in a wired network since they usually have a limited screen size and thus focus only on part of a whole document. We evaluate the performance of a simple group editor with the propose scheme using ns -2. The performance results show that the proposed scheme keeps the message transmission delay low so that mobile users can have synchronous colloboration with wired users without signification delay. The proposed scheme is designed and implemented as a framework to support various kinds of realtime groupware applications, exploiting the existing groupware framework, Habanero. As a client program, we implemented a simple group text editor.

• Journal of KIISE:Software and Applications
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• v.34 no.9
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• pp.817-827
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• 2007

In the age of ubiquitous environment, huge number of devices and computing services are provided to users. Personalized service, which is modeled according to the character of each and every individual is of particular need. In order to provide various dynamic services according to user's movement, service unit and operating mode should be able to operate automatically with minimum user intervention. In this paper, we discuss the steps of offering approximate service based on user's request in ubiquitous environment. First, we present our simulator designed for modeling the physical resource and computing object in smart space - the infrastructure in ubiquitous. Second, intelligent agents, which we developed based on a FIPA specification compliant multi-agent framework will be discussed. These intelligent agents are developed for achieving the service goal through cooperation between distributed agents. Third, we propose an automated service discovery and composition method in heterogeneous environment using semantic message communication between agents, according to the movement by the user interacting with the service available in the smart space. Fourth, we provide personalized service through agent monitoring anytime, anywhere from user's profile information stored on handhold device. Therefore, our research provides high quality service more than general automated service operation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.8
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• pp.3777-3785
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• 2013

This study aimed to find out adolescents' media literacy in terms of reading, writing, and enjoying media or messages. For the purpose, we analyzed the data garnered from 1,036 students enrolled in 5 middle and 5 high schools, respectively. The analyses of the data are summarized as follows: First, mobile phone was most widely used among others, followed by TV, the Internet, mp3 player, computer or video game, radio, a video or DVD in the order. Second, a gender effect was significant in terms of the variety of activities with the Internet, mobile, and SNS: boys were more active in the use of the Internet while girls carried out more activities with a mobile phone and SNS media. Third, high school students showed more critical attitude towards information on the Website than did the middle school students. Fourth, Girls than boys, and high schoolers than middle schoolers, tended to be more active in the production of contents, self-expression, as well as participating in social and political issues online. Fifth, for the enjoyment experiences, time spent for games took up the most of the students' leisure activities, followed by watching TV and the use of the Internet. The findings of the study were discussed in light of media convergence, with implications for developing media literacy education for the youth.

• Journal of KIISE:Databases
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• v.34 no.6
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• pp.528-545
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• 2007

Recently ontology has been an attractive technology along with the business strategy of providing a plenty of more intelligent services. The essential problem in application domains using ontology is that all members, agents, and application programs in the domains must share the same ontology concepts. However, a variety of mobile devices, sensing devices, and network components manufactured by various companies, a variety of common carriers, and a variety of contents providers make multiple heterogeneous ontologies more likely to coexist. We can see many past researches fallen into resolving this semantic interoperability. Such methods can be broadly classified into by-mapping, by-merging, and by-translation. In this research, we focus on by-translation among them which uses a translation rule directly made between two heterogeneous ontology data like OntoMorph. However, the manual composition of the direct translation rule is not convenient by itself and if there are N ontologies, the direct method has the rule composition complexity of $O(N^2)$ in the worst case. Therefore, in this paper we introduce the cascade composition of translation rules based on web openness in order to improve the complexity. The research result made us recognize some important factors in an ontology translation system, that is speediness of translation, and conveniency of translation rule composition, and some experiments and comparing analysis with existing methods showed that our cascade method has more conveniency with insuring the speediness and the correctness.

• Journal of Advanced Navigation Technology
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• v.19 no.5
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• pp.423-432
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• 2015

This paper shows that design, manufacture and the performance of FC-NIC (fibre channel network interface card) for network unit configuration which is based on one of the 5 main configuration items of the common functional module for IMA (integrated modular Avionics) architecture. Especially, FC-NIC uses zynq SoC (system on chip) for host load reductions. The host merely transmit FC destination address, source memory location and size information to the FC-NIC. After then the FC-NIC read the host memory via DMA (direct memory access). FC upper layer protocol and sequence process at local processor and programmable logic of FC-NIC zynq SoC. It enables to free from host load for external communication. The performance of FC-NIC shows average 5.47 us low end-to-end latency at 2.125 Gbps line speed. It represent that FC-NIC is one of good candidate network for IMA.

• Journal of KIISE:Information Networking
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• v.31 no.5
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• pp.490-500
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• 2004

In mobile/wireless environment, mobility management is widely being focused as one popular researches. But, disruption happens when messages are exchanged between nodes as registration is made after handoff, and unnecessary traffic occurs because of the use of the Random-walk model, in which the probability for MN to move to neighboring cells is equal. In order to solve these problems, this study proposes a technique and algorithm for composing Directional Shadow Registration Region (DSRR) that provides seamless mobility. The core of DSRR is to prevent disruption and unnecessary traffic by minimizing the number o) neighboring cells with a high probability of handoff (AAAF). This study sensed the optimal time for handoff through regional cell division by introducing a division scheme, and then decided DSRR, the region for shadow registration, by applying direction vector (DV) obtained through directional cell sectoring. According to the result of the experiment, the proposed DSRR processes message exchange between nodes within the intra-domain, the frequency of disruptions decreased significantly compared to that in previous researches that process in inter-domain environment. In addition, traffic that occurs at every handoff happened twice in DSRR compared to n (the number of neighboring cells) times in Previous researches. As an additional effect, divided regions obtained from the process of composing DSRR filter MN that moves regardless of handoff.

• The KIPS Transactions:PartC
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• v.18C no.5
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• pp.331-338
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• 2011

The RFID system includes a section of wireless communication between the readers and the tags. Because of its vulnerability in terms of security, this part is always targeted by attackers and causes various security problems including the leakage of secret and the invasion of privacy. In response to these problems, various protocols have been proposed, but because many of them have been hardly implementable they have been limited to theoretical description and theorem proving without the accurate verification of their safety. Thus, this study tested whether the protocol proposed by Kenji et al. satisfies security requirements, and identified its vulnerabilities such as the exposure of IDs and messages. In addition, we proposed an improved RFID security protocol that reduced the number of public keys and random numbers. As one of its main characteristics, the proposed protocol was designed to avoid unnecessary calculations and to remove vulnerabilities in terms of security. In order to develop and verify a safe protocol, we tested the protocol using Casper and FDR(Failure Divergence Refinements) and confirmed that the proposed protocol is safe in terms of security. Furthermore, the academic contributions of this study are summarized as follows. First, this study tested the safety of a security protocol through model checking, going beyond theorem proving. Second, this study suggested a more effective method for protocol development through verification using FDR.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.3
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• pp.48-58
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• 2009

Geo-graphical routing protocols as GPSR are known to be very suitable and useful for vehicular ad-hoc networks. However, a corresponding node can include some stale neighbor nodes being out of a transmission range, and the stale nodes are pone to get a high priority to be a next relay node in the greedy mode. In addition, some useful redundant information can be eliminated during planarization in the recovery mode. This paper deals with a new recovery mode, the Greedy Border Superiority Routing(GBSR), along with an Adaptive Neighbor list Management(ANM) scheme. Each node can easily treat stale nodes on its neighbor list by means of comparing previous and current Position of a neighbor. When a node meets the local maximum, it makes use of a border superior graph to recover from it. This approach improve the packet delivery ratio while it decreases the time to recover from the local maximum. We evaluate the performance of the proposed methods using a network simulator. The results shown that the proposed protocol reveals much better performance than GPSR protocol. Please Put the of paper here.