• The Journal of the Korea Contents Association
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• v.8 no.7
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• pp.43-52
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• 2008

The AODV routing algorithm in a mobile ad-hoc networks broadcasts RREQ packet to find a route from a source to a destination. An attacker node may intercept a RREQ packet and attack by falsifying a field in that packet. In this paper, we propose a simply modified method which can protect a routing table from an attack to falsify the hop count field in the RREQ packet. When establishing a connection between a source and a destination, we update routing table of each node on the connection based on minimum delay instead of minimum hop count. By doing this, we can protect routing table from an attack to falsify a hop count Our simulation is implemented in Network Simulator(NS-2). We analyze how an attacker affects the mobile ad-hoc networks. The result of the simulation shows that the proposed mechanism transfers a data securely.

• Journal of the Korea Society of Computer and Information
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• v.17 no.11
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• pp.73-81
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• 2012

This paper proposes an ETWAD(Encapsulation and Tunneling Wormhole Attack Detection) design based on positional information and hop count on Ad-Hoc Network. The ETWAD technique is designed for generating GAK(Group Authentication Key) to ascertain the node ID and group key within Ad-hoc Network and authenticating a member of Ad-hoc Network by appending it to RREQ and RREP. In addition, A GeoWAD algorithm detecting Encapsulation and Tunneling Wormhole Attack by using a hop count about the number of Hops within RREP message and a critical value about the distance between a source node S and a destination node D is also presented in ETWAD technique. Therefore, as this paper is estimated as the average probability of Wormhole Attack detection 91%and average FPR 4.4%, it improves the reliability and probability of Wormhole Attack Detection.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06a
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• pp.416-419
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• 2011

무선 센서 네트워크 환경에서 효율적인 데이터 수집 기업은 핵심적인 기반 기술이다. 클러스터 기반의 데이터 수집 기법은 데이터 병합 (aggregation) 의 효율을 최대화 시켜 센서 노드들의 에너지 소모를 최소화 시킨다. 하지만 기존의 클러스터링 기법은 균일한 네트워크 환경만을 고려하여 불균일하게 배포될 수 있는 실제 환경에는 적합하지 않다. 본 논문에서는 기존 기업들의 문제점을 해결하기 위해 불균일한 네트워크 환경에서도 에너지 효율적인 클러스터를 구축할 수 있는 기업을 제안한다. 제안하는 기법은 클러스터 헤드를 기준으로 최단 거리 홉 카운트 기법을 통해 논리적인 거리를 기반으로 클러스터 멤버를 구성한다. 이를 통해 불균일한 네트워크 환경에서도 클러스터들 간에 균형적인 멀티-홉 클러스터를 구축하여 네트워크 수명을 최대화 시킨다. 제안하는 기법의 우수성을 모이기 위해 기존 기법과 시뮬레이션을 통해 성능을 비교평가 하였다.

• Journal of Internet Computing and Services
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• v.10 no.5
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• pp.27-32
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• 2009

Colored thread algorithm, suggested to be used for the label switching network, needs to be modified for the packet switching network. In this paper, it is recommended to add a merged state, besides the 3 states - null, colored and transparent - which are resulted from the behaviors of extend, rewind, stall, withdraw and merge events. The original colored thread algorithm is designed to generate a new thread and extend it to the downstream direction with unknown hop count when the thread has revisited the node that was visited. It also suggested rewinding the thread to the downstream direction by the source node, instead of rewinding it upstream direction by the revisited node. If a node received multiple threads which had a same forward equivalent class, then it checks first whether the hop counts are ascending or not. If it is in ascending order, then threads are merged. Otherwise the later thread is stalled until the former thread's color is to be changed to transparent or it is removed. This idea removes the effort of generating a new thread with unknown hop count.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.10
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• pp.2257-2264
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• 2011

Sensor nodes in Wireless sensor network have limited resources and consume almost all energy to the communication. For its traffic feature as a burst traffic type toward a sink node, it has high probability to network congestion. Network congestion causes packet drops and retransmission of dropped packets draws energy consumption. In particular, the loss of packet that is from the sensor node far away from a sink node requires additional energy consumption by frequent retransmission. This paper presents a traffic control mechanism that determines packet transfer by considering priority of packet and congestion level as well as hop count. Analysis of proposed mechanism by simulation demonstrated that it improved energy efficiency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.715-718
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• 2016

SpaceWire invented for on-board data handling in a spacecraft has Time-Code defined for time synchronization over SpaceWire network. Delay and jitter of the transmission of Time-Code caused when a Time-Code travels through a network are the main reasons of time synchronization error. This work proposes a scheme that can reduce the time synchronization error by using extended Time-Codes. The proposed scheme can remove both transmission jitter and transmission delay. The scheme will be validated in a simulation environment built with OMNeT++.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.6
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• pp.1462-1470
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• 2013

This paper proposes an SWAD-KNH(Sybil & Wormhole Attack Detection using Key, Neighbor list and Hop count) technique which consists of an SWAD(Sybil & Wormhole Attack Detection) module detecting an Worm attack and a KGDC(Key Generation and Distribution based on Cluster) module generating and an sense node key and a Group key by the cluster and distributing them. The KGDC module generates a group key and an sense node key by using an ECDH algorithm, a hash function, and a key-chain technique and distributes them safely. An SWAD module strengthens the detection of an Sybil attack by accomplishing 2-step key acknowledgement procedure and detects a Wormhole attack by using the number of the common neighbor nodes and hop counts of an source and destination node. As the result of the SWAD-KNH technique shows an Sybil attack detection rate is 91.2% and its average FPR 3.82%, a Wormhole attack detection rate is 90%, and its average FPR 4.64%, Sybil and wormhole attack detection rate and its reliability are improved.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1C
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• pp.45-53
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• 2012

In this paper, we proposed the efficient addressing scheme for improving the performance of routing algorithm by using ZigBee in Smart Grid environment. A distributed address allocation scheme used an existing algorithm that has wasted in address space. Therefore proposing x, y and z coordinate axes from divided address space of 16 bit to solve this problems. 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 verified performance about decrease averaging multi hop count that compare proposing algorithm and another. The numerical analysis results show that proposed algorithm reduced the multi hop better than ZigBee distributed address assignmen.

• Proceedings of the Korea Contents Association Conference
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• 2005.05a
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• pp.396-400
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• 2005

In this paper, we propose an efficient full mesh topology aggregation method in PNNI networks. The proposed scheme can search multi-links efficiently using the depth priority method based on hop count instead of searching the all links. To evaluate performance of the proposed scheme, we compare/analyze the current method with the proposed scheme with respect to call success rate, access time and crankback rate. The result is that the proposed scheme is better than the current scheme in performance.

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.245-256
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• 2009

Pastry overlay network is one of structured P2Ps using DHT(Distributed Hash Table). To reduce the number of messages among nodes, Rosary and LAR have been proposed by exploiting spatial locality and caching, respectively, in the Pastry. Rosary consists of Inter-Pastry and Intra-Pastry. A root node is assigned as a representative in each Intra-Pastry and it has the responsibility of Inter-Pastry and Intra-Pastry routing. Therefore, Rosary has several disadvantages; 1) low fault tolerance in case of root node failure 2) routing hop count increases because of the use of root nodes compared to the existing structured P2Ps, and 3) the communication load is concentrated in some specific areas. LAR has inefficient problems in that caching is not distributed among nodes in Intra-Pastry and caching is used by only nodes in the Intra-Pastry. In this paper, we propose an improved Pastry called Doughnut to overcome the above problems of Rosary and LAR. By dividing nodes with the local characteristics, the Doughnut consists of Inter-Pastry and Intra-Pastry, and all nodes have the responsibility of Inter-Pastry and Intra-Pastry routing. This results in that all nodes perform the role of the existing root node. This solves the problems of the reducing of fault-tolerance, the increasing of routing hop count, and the not-distributed communication load. Also Doughnut can use cache effectively because it guarantees the even cache distribution in local(Intra-Pastry) and the cache contents in local can be used in the other local. The proposed algorithm is implemented using simulator and the experimental results show the effectiveness of the proposed method compared to the existing method.