• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7B
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• pp.728-733
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• 2009

An ubiquitous environment has features like peer-to-peer and nomadic environments. Such features can be represented by peer-to-peer systems and mobile ad-hoc networks. P2P systems and MANETs share similar features, appealing for implementing P2P systems in MANET environment. However, if a P2P system designed for wired networks was applied to mobile ad-hoc environment, its performance was not good enough. Subsequently, this paper proposes a P2P system to improve performance using cross-layer design and the goodness of a node as a peer by using routing metric and P2P metric to choose favorable peers to connect. It also utilizes proactive approach for distributing peer information. The simulation results showed that the proposed system produced better performance in query success rate, query response time and energy consumption by reducing the routing path length.

• The KIPS Transactions:PartD
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• v.11D no.2
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• pp.351-360
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• 2004

Most mobile agents are migrated to many mobile agent systems by the sequential node migration method. However. in this case, if some problems such as host's fault or obstacle etc. happened, mobile agent falls infinity walt or orphan states. Therefore, it is difficult to get an expectation effect as use of other distribution technologies because the required time for networking between nodes increases. And so, many researches have been performed to solve this problems. However, most of methods decide node migration based on passive routing table or detour hosts which have some problems. Actually, the researches for reducing the total required time for networking are insufficient yet. In this paper, to reduce the required time for networking of mobile agent we design an active routing table based on the information of implemented objects which are registered in the meta-table of naming agent. And also, for user's keyword, we propose an replication model that replicates many agent object according to the information and number of object references corresponding to meta-table. Replicated objects are migrated to mobile agent systems in parallel and it provides minimized required time for networking.

• Journal of Korea Multimedia Society
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• v.11 no.4
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• pp.544-553
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• 2008

The general sensor network uses bundle method to collect fixed information from sensor node. However, this method is difficult to actively cope with major sensing objects in healthcare environment including status and position change of person and change of surrounding environment. In order to support the healthcare environment, certain information should be provided in accordance with the change of status of person and surrounding circumstance and also must cope with the change of network type by movement of person. This paper analyzes LEACH protocol which guarantees effectiveness of network as it constitutes clusters between Agilla model that is a representative multi agent middle ware and surrounding nodes. Based on the result of this analysis, it suggests LEACH_Mobile protocol which guarantees node mobility that is the weakest point of LEACH protocol. Moreover, it designs mobility agent middleware which supports dynamic function change of node and mobility agent module which supports dynamic function change of mobile node as components of LEACH_Mobile routing module. In addition, it is definitely increase performance which in mobile node of transfer data rate through LEACH_Mobile protocol of simulation result.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.61-69
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• 2012

Smart Grid is the next-generation intelligent power grid that maximizes energy efficiency with the convergence of IT technologies and the existing power grid. Smart Grid is created solution for standardization and interoperability. Smart Grid industry enables consumers to check power rates in real time for active power consumption. It also enables suppliers to measure their expected power generation load, which stabilizes the operation of the power system. Smart industy was ecolved actively cause Wireless communication is being considered for AMI system and wireless communication using ZigBee sensor has been applied in various industly. In this paper, we proposed efficient addressing scheme for improving the performance of the routing algorithm using ZigBee in Smart Grid environment. A distributed address allocation scheme used an existing algorithm has wasted address space. Therefore proposing x, y coordinate axes from divide address space of 16 bit to solve this problem. Each node was reduced not only bitwise but also multi hop using the coordinate axes while routing than Cskip algorithm. I compared the performance between the standard and the proposed mechanism through the numerical analysis. Simulation verify performance about decrease averaging multi hop count that compare proposing algorithm and another. The numerical analysis results show that proposed algorithm reduce multi hop than ZigBee distributed address assignment and another.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.6
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• pp.580-586
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• 2017

The establishment of big data service environment requires both cloud-based network technology and clustering technology to improve the efficiency of information access. These cloud-based networks and clustering environments can provide variety of valuable information in real-time, which can be an intensive target of attackers attempting illegal access. In particular, attackers attempting IP spoofing can analyze information of mutual trust hosts constituting clustering, and attempt to attack directly to system existing in the cluster. Therefore, it is necessary to detect and respond to illegal attacks quickly, and it is demanded that the security policy is stronger than the security system that is constructed and operated in the existing single system. In this paper, we investigate routing pattern changes and use them as detection information to enable active correspondence and efficient information service in illegal attacks at this network environment. In addition, through the step-by -step encryption based on the routing information generated during the detection process, it is possible to manage the stable service information without frequent disconnection of the information service for resetting.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.4
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• pp.433-438
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• 2014

The demanding in construction of the stand-alone networks and interconnection between convergence devices have led an increase in research on MANET and the application of MANET has been paid much attention as a Ubiquitous computing which is growing fast in the field of computer science. With performance both as hosts and routers, easy network configuration, and fast response, mobile nodes participating in MANET are suitable for Embedded computing but have vulnerable points, about lack of dynamic network topology due to mobility, network scalability, passive attacks, and active attacks which make it impossible to manage continuous security authentication service. In this study, proposes S-EKE authentication mechanism for a robust authentication based on MANET and through identify wireless environment security vulnerabilities, currently being used in OTP S/Key and DH-EKE analyzes.

• Convergence Security Journal
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• v.15 no.3_1
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• pp.75-82
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• 2015

Recently, lot of researches on multi-level protocol have been done to balance the sensor node energy consumption of WSN and to improve the node efficiency to extend the life of the entire network. Especially in multi-hop protocol, a variety of models have been studied to improve energy efficiency and apply it in real system. In multi-hop protocol, we assume that energy consumption can be adjusted based on the distance between the sensor nodes. However, according to the physical property of the actual WSN, it's hard to establish this. In this paper, we propose low-power sub-cluster protocol to improve the energy efficiency based on the spread of distance. Compared with the previous protocols, the proposed protocol is energy efficient and can be effectively used in the wireless sensing network.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.1267-1270
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• 2000

위성통신 시스템은 기존의 지상망이나 광 케이블 기술에 비해 통신 대역폭의 유연성과 다중 접속능력, 이동통신, 광역성, 멀티포인트 및 브로드캐스팅 등의 본래의 특징으로 인해 초고속정보통신망 구축에 중요한 역할을 하게 된다. 특히 OBP (On-Board Processing) 기술을 적용하면 기존 위성통신 탑재장치의 수동적인 중계 기능 이외에 복조/재변조, 부호/복호화 및 오류정정, 중계기 및 빔간의 상호 연결/절체 등의 새로운 기능이 추가되어 능동적인 중계를 가능하게 함으로써 통신 품질의 향상, 통신 링크의 전송 효율 개선, 전송 용량 증대 등의 장점을 갖고있다. OBP 탑재 위성 B-IDSN 중계망은 하나의 거대한 가상 ATM 교환기로 간주되고, 여러중계 지구국들중 목적 중계 지구국으로 패킷들을 직접 라우팅 할 수 있는 장점이 있다. 본 논문은 OBP 탑재 위성 B-ISDN 연동 프로토콜 연구를 수행하는 것으로서, 위성 B-ISDN 구조와 각 지구국별 신호 기능 및 B-IDSN 신호 시스템인 DSS2 계층 3 신호 프로토콜, B-ISUP 프로토콜, S-BISUP 프로토콜의 구조를 분석하였다. 또한 점-대-다지점을 위한 B-ISDN의 연결과 소유권 및 각각의 프로토콜에 대한 메시지와 프리미티브를 정의하여, 이를 토대로 OBP 탑재 위성 B-IDSN 연동 프로토콜의 기본 호 처리 절차를 설계 및 구현하고, 이를 테스트하였다.

• Journal of KIISE:Information Networking
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• v.30 no.4
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• pp.513-519
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• 2003

In order to deliver multicast traffic efficiently, multicast routing and reliable transmission mechanisms are required. The reliable delivery implies that lost packets must be retransmitted, which in turn requires that transmitted packets be stored in a retransmission buffer. Therefore how to manage a retransmission buffer is important and, in this paper, we try to solve the problem of how many packets should be maintained in the buffer. Our proposed scheme, the timer-based buffer management (TBM), maintains only necessary amount of buffer based on the timer value calculated from the NAKs between the replier and receivers on a multicast tree and can adjust to the dynamic network conditions. By performing simulations, we show that TBM manages the buffer efficiently regardless of the error situation, network size, and so on.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1178-1181
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• 2009

Geographic forwarding algorithms을 사용하는 Georouting protocol에서는 route maintenance을 위해서 고정된 주기마다 beacon message을 이웃노드에 전송하는 fixed periodical beacon based route algorithm을 사용하여 mobile node 정보를 습득한다. Fixed periodical beacon scheme에서의 기존 연구 이슈는 이웃노드 정보의 신뢰성을 유지하기 위해서 다양한 mobility environment 환경에 맞도록 beacon 전송주기를 적절히 결정하는 연구가 진행되어 왔다. 이와 같은 연구에서는 long periodical interval 사용 시 이웃노드의 위치정보 error을 발생시킬 확률이 높으며 또한 short periodical interval 의 경우 네트워크 내에 high route overhead 을 유발시키는 단점을 가지고 있다. 따라서 고정된 주기 방법은 다양한 mobility environment에 잘 적용되지 못하며 또한 mobility environment 에서 발생하는 route maintenance 내에 이웃노드 정보에 대한 불확실성 문제가 빈번이 발생하여 경로 설정에 잘못된 정보를 제공하여 경로 신뢰성(path reliability)과 낮은 전송률 (transmission rate)을 야기한다. 본 논문에서는 이런 이웃노드 정보의 불확실성 문제를 극복하기 위해서 mobile node가 스스로 자신의 위치를 체크하여 routing table을 능동적으로 갱신하는 방법을 이용하여 이 문제를 극복할 수 있도록 하였다. 모의 실험은 ns2를 이용하여 실시하였으며 결과는 low/high mobility scenario에서는 기존 방법 보다 routing overhead 을 줄이면서 높은 전송률 (transmission rate)을 보인다.