• Journal of Korea Multimedia Society
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• v.7 no.3
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• pp.388-398
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• 2004

This paper focuses on the reduction method of message traffic occurred when multiple participants collaborate in the distributed virtual environment. It is referred to as filtering method of update message to minimize data traffic exchanged in the virtual environment, and it is the essential process to improve the scalability of the virtual environment. Spatial partitioning method, a popular filtering technique, divides the whole environment into smaller sub-parts in order to make it small the regions to be maintained consistently. However, it is less flexible and adaptable because the information of area of interest must be configured before simulation. In this paper, the concept of dynamic area of interest is proposed, which is highly adaptable by applying dynamic environmental elements to AOI management. It uses multiple layering and multiple consistency algorithms for dynamic management, and makes it possible to consume system resource efficiently. For performance evaluation, experiments are performed with virtual avatars, measuring message traffic. Finally, the proposed model could be applied to the AOI management systems which accommodate massive users like MMORPG, or virtual communities.

• The KIPS Transactions:PartD
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• v.9D no.6
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• pp.999-1008
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• 2002

XML is emerging as a standard data format to exchange and to present data on the Web. There are increasing needs to efficiently store and to query XML data. In this paper. we propose a new schema transformation algorithm based on a common structure extracting technique from XML documents. The common structure is shared by all XML documents referenced by DTD and the uncommon structure is ununiformly appeared on all XML documents referenced by DTD. Based on the extracted common and uncommon structures, we transform XML DTD into relational database schema. We conduct a performance evaluation based on the number of the generated tables, the size of the record, query processing time and the number of joins on the query. The performance of our algorithm is compared with the existing algorithms, then in most cates, our algorithm is better than the existing ones with respect to the number of the generated tables and appearance of NULL values in the tables.

• Journal of the Korea Society of Computer and Information
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• v.18 no.3
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• pp.35-45
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• 2013

MANET has a weak point because it allows access from not only legal nodes but also illegal nodes. Most of the MANET researches had been focused on attack on routing path or packet forwarding. Nevertheless, there are insuffcient studies on a comprehensive approach to detect various attacks on malicious nodes at packet forwarding processes. In this paper, we propose a technique, named DTecBC (detection technique of malicious node behaviors based on collaboration), which can handle more effciently various types of malicious node attacks on MANET environment. The DTecBC is designed to detect malicious nodes by communication between neighboring nodes, and manage malicious nodes using a maintain table. OPNET tool was used to compare with Watchdog, CONFIDANT, SRRPPnT for verifying effectiveness of our approach. As a result, DTecBC detects various behaviors of malicious nodes more effectively than other techniques.

• The KIPS Transactions:PartA
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• v.17A no.4
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• pp.181-188
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• 2010

In this study, we suggest the system to analyze network users' action patterns by using Data-Mining Technique. We installed Network Tap to implement the analysis system of network action and copied the network packet. The copied packet is stored at the database through MainMemoryDB(MMDB) of the high-speed. The stored data analyze the users' action patterns by using Data-Mining Technique and then report the results to the network manager on real-time. Also, we applied the standard XML document exchange method to share the data between different systems. We propose this action pattern analysis system operated embedded type of SetToBox to install easily and support low price.

• The KIPS Transactions:PartD
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• v.12D no.2 s.98
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• pp.189-198
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• 2005

XML is rapidly becoming the standard for data representation and exchange, and XML documents are being adopted in various applications. Since the late 1990s, some native XML database management systems(DBMSs) have been developed. More recently, commercial relational DBMS vendors try to incorporate full functionalities of XML into their products, such as Oracle, MS SQL and IBM DB2. In this paper, we implement a well-known RDBMS-based XML data storage and indexing technique, called XPath Accelerator, and tune it in an industry-leading RDBMS. Our contributions are two-folds: 1) an in-depth implementation of the XPath Accelerator technique and 2) its tuning to exploit the advanced query processing techniques of an RDBMS.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11c
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• pp.2157-2160
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• 2002

무선 인터넷의 급속한 발전과 무선 단말기 성능의 발달로 인해 무선 단말기를 이용한 저자상거래(M-Commerce)가 활성화되고 있다. 따라서 전자상거래시 중요한 문제점으로 여겨지는 데이터 보안이나 사용자 인증 같은 기술이 M-Commerce 환경에서도 적용될 수 있는 연구가 현재 활발히 진행되고 있으며, 대표적인 연구로는 WPKI가 있다. 또한 유선 인터넷 환경에서의 전자상거래는 XML을 통한 문서교환 연구가 활발하게 진해 중에 있기 때문에 XML 전자서명에 관한 연구가 많이 이루어지고 있다. 따라서 본 논문에서는 무선 인터넷 환경에 XML 전자서명 기법을 적용하여 사용자 인증과 XML 문서 및 전자서명 시스템들 간에 상호 연동성을 제공할 수 있는 Mediator를 설계하였다. 본 논문을 통해 무선 인터넷 환경에서도 XML 전자서명 포맷을 제공하여 XML 문서을 이용한 전자상거래 범위를 무선 인터넷 환경으로 확대할 수 있으며, 기존 유선 인터넷 환경에서 사용되는 XML 문서 기반 전자상거래 시스템과도 서로 상호 연동 가능하다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1225-1228
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• 2007

무선 네트워크와 모바일 기술의 발달로 무선상에서의 통신뿐만 아니라, 모바일 기기의 이동성에 대한 요구가 점점 더 커지고 있다. 모바일 기기의 이동성을 지원하기 위해Fast Mobile IPv6 (FMIPv6), Hierarchical Mobile IPv6 (HMIPv6)와 같은IPv6기반의 네트워크 계층 프로토콜이 제안되어 왔으며, 최근에는 트랜스포트 계층에서 동작하는 mobile Stream Control Transport Protocol (mSCTP) 가 제안 되었다. 네트워크 계층에서의 이동성을 지원하기 위한 방안 중 하나인 FMIPv6 의 핸드오프 과정은 엑세스 라우터간 양방향 터널링을 설정 함으로서 엑세스 라우터의 버퍼링 오버헤드가 발생하고, 터널링 과정을 위한 메시지 교환으로 인해 핸드오프 지연이 발생하게 된다. 본 논문에서는 FMIPv6 의 이러한 단점을 해결하기 위해 트랜스포트 계층의 이동성 지원 방안인 mSCTP 를 이용한 통합 핸드오프 기법을 제안한다. 양단의 세션을 유지한 채 새로운 IP 주소를 등록 할 수 있는 mSCTP 를 사용 함으로서 FMIPv6 의 터널링으로 인해서 발생하는 엑세스 라우터의 오버헤드와 핸드오프 지연 시간을 줄이고 전체적인 핸드오프 성능을 향상 시킨다.

• The KIPS Transactions:PartC
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• v.14C no.7
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• pp.603-610
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• 2007

Effective handover decision is important for providing seamless services to mobile users. In this paper, we propose an analysis framework to evaluate the performance of handover decision based on received signal strength (RSS) measurements in terms of the late notification and false alarm probability. In our framework, we consider mobility of a mobile user, signaling delays for exchanging messages related to handover protocols, cell sizes and RSS measurement interval to stabilize RSS reading due to random measurement errors. By quantitatively scrutinizing the impact of each parameter on the late notification and false alarms, we suggest the research directions for effective handover decision mechanism that may provide fast and reliable handover.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.3
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• pp.180-187
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• 2014

This paper introduces reliable multicast MAC protocol for cooperative unmanned vehicles. cooperative unmanned vehicles communicate with infrastructure and other unmanned vehicles in order to increase driving safety. They exchange information related to driving and thus it requires real-time and reliable multicast. However, the international vehicular communication standard, IEEE 802.11p WAVE, does not provide a reliable multicast scheme on the MAC layer. To address the problems of reliability, we propose a reliable multicast protocol called WiVCL, which avoids contention and collision. Our evaluation shows that the WiVCL achieves a high degree of reliability and real-time features.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.367-370
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• 2011

Tactical communication environment evolving for the purpose of providing services such as voice, video and text based on ALL-IP. Therefore, To be able to guarantee QoS level which meets the required level of subscriber for these services in the constrained tactical communication infrastructure, it is required to take the characteristics such as wireless transmission link, mobility of troops or personal into service quality scheme. In this paper, to support differentiated QoS for each individual or mission in the tactical communication environment, we presents a technique that can provide same QoS level which was served originally regardless of the situation to user's move through dynamically determining the QoS level to be provided at the time of the service request on VoIP-Switch.