• International Journal of Fuzzy Logic and Intelligent Systems
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• 제8권2호
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• pp.121-125
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• 2008

It is essential to maintain hierarchical information properly for efficient XML query processing. Well known approach to represent hierarchical information of XML tree is assigning a specific node number to each node of XML tree. Insertion and deletion of XML node can occur at any position in a dynamic XML tree. A dynamic numbering scheme allows us to add nodes to or delete nodes from an XML tree without relabeling or with relabeling only a few existing nodes of XML tree while executing XML query efficiently. According to W3C XQuery update facility specifications a node can be added as first or last child of the existing node in XML tree. Generating new number for last child requires referencing the number of previous last child. Getting the number of last child is very costly with previous approaches. We have developed a new dynamic numbering scheme PSN which is very effective for insertion of a node as last child. Our approach reduces the time to find last child dramatically by removing sorting of children.

• Journal of Communications and Networks
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• 제15권2호
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• pp.122-131
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• 2013

We address the problem of effective vehicular routing in hostile scenarios where malicious nodes intend to jeopardize the delivery of messages. Compromised vehicles can severely affect the performance of the network by a number of attacks, such as selectively dropping messages, manipulating them on the fly, and the likes. One of the best performing solutions that has been used in static wireless sensor networks to deal with these attacks is based on the concept of watchdog nodes (also known as guard nodes) that collaborate to continue the forwarding of data packets in case a malicious behavior in a neighbor node is detected. In this work, we consider the beacon-less routing algorithm for vehicular environments routing protocol, which has been previously shown to perform very well in vehicular networks, and analyze whether a similar solution would be feasible for vehicular environments. Our simulation results in an urban scenario show that watchdog nodes are able to avoid up to a 50% of packet drops across different network densities and for different number of attackers, without introducing a significant increase in terms of control overhead. However, the overall performance of the routing protocol is still far from optimal. Thus, in the case of vehicular networks, watchdog nodes alone are not able to completely alleviate these security threats.

• 대한임베디드공학회논문지
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• 제4권1호
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• pp.42-49
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• 2009

Most Vehicular Ad hoc Network (VANET) applications rely heavily on broadcast transmission of traffic related information to all reachable nodes within a certain geographical area. Among various broadcast approaches, flooding is the first broadcasting technique. Each node rebroadcasts the received message exactly once, which results in broadcast storm problems. Some mechanisms have been proposed to improve flooding in Mobile Ad hoc Networks (MANET), but they are not effective for VANET and only a few studies have addressed this issue. We propose two distance-based and timer-based broadcast suppression techniques: 15P(15percent) and slotted 15P. In the first (distance based) scheme, node's transmission range is divided into three ranges (80%,15%and5%). Only nodes within 15% range will rebroadcast received packet. Specific packet retransmission range (15%) is introduced to reduce the number of messages reforwarding nodes that will mitigate the broadcaststorm. In the second (timer-based) scheme, waiting time allocation for nodes within 15% range isused to significantly reduce the broadcaststorm. The proposed schemes are distributed and reliedon GPS information and do not requireany other prior knowledge about network topology. To analyze the performance of proposed schemes, statistics such as link load and the number of retransmitted nodes are presented. Our simulation results show that the proposed schemes can significantly reduce link load at high node densities up to 90 percent compared to a simple broadcast flooding technique.

• 한국정보통신학회논문지
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• 제9권1호
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• pp.58-64
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• 2005

본 논문은 Ad-hoc 네트워크에서의 전송을 효율적으로 하기 위한 클러스터링 알고리즘에 대해 실험을 통하여 살펴보았다. Ad-hoc 네트워크상 노드들은 정보전송과 위치등록, 노드간의 라우팅 경로 유지를 위해 많은 패킷전송이 이루어진다. 이러한 환경에서의 트래픽은 고정망에서 보다 이동성 변수에 따라 더욱 많은 수가 발생하게 될 것이다. 본 논문에서는 무선 Ad-hoc 다중 홉에서의 트래픽 제어를 위한 클러스터링 알고리즘을 통해 패킷 전송효율을 분석하여 그 결과를 제시한다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 춘계학술대회
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• pp.653-655
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• 2015

본 논문은 Ad-hoc 네트워크에서의 전송을 효율적으로 하기 위한 클러스터링 알고리즘에 대해 실험을 통하여 살펴보았다. Ad-hoc 네트워크상 노드들은 정보전송과 위치등록, 노드간의 라우팅 경로유지를 위해 많은 패킷전송이 이루어진다. 본 논문에서는 무선 Ad-hoc 통신망에서 요구되는 알고리즘 프로그램개발을 통하여 패킷 전송효율을 분석을 통해 문자메세지, 무료통화가 가능한 알고리즘을 개발하여 향후 통신 서비스 산업에 적용가능함을 제시한다.

• International Journal of Computer Science & Network Security
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• 제21권9호
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• pp.1-10
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• 2021

The Internet of things (IoT) is the main advancement in data processing and communication technologies. In IoT, intelligent devices play an exciting role in wireless communication. Although, sensor nodes are low-cost devices for communication and data gathering. However, sensor nodes are more vulnerable to different security threats because these nodes have continuous access to the internet. Therefore, the multiparty security credential-based key generation mechanism provides effective security against several attacks. The key generation-based methods are implemented at sensor nodes, edge nodes, and also at server nodes for secure communication. The main challenging issue in a collaborative key generation scheme is the extensive multiplication. When the number of parties increased the multiplications are more complex. Thus, the computational cost of batch key and multiparty key-based schemes is high. This paper presents a Secure Multipart Key Distribution scheme (SMKD) that provides secure communication among the nodes by generating a multiparty secure key for communication. In this paper, we provide node authentication and session key generation mechanism among mobile nodes, head nodes, and trusted servers. We analyzed the achievements of the SMKD scheme against SPPDA, PPDAS, and PFDA schemes. Thus, the simulation environment is established by employing an NS 2. Simulation results prove that the performance of SMKD is better in terms of communication cost, computational cost, and energy consumption.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권4호
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• pp.1224-1248
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• 2022

In various sensor network applications, such as climate observation organizations, sensor nodes need to collect information from time to time and pass it on to the recipient of information through multiple bounces. According to field tests, this information corresponds to most of the energy use of the sensor hub. Decreasing the measurement of information transmission in sensor networks becomes an important issue.Compression sensing (CS) can reduce the amount of information delivered to the network and reduce traffic load. However, the total number of classification of information delivered using pure CS is still enormous. The hybrid technique for utilizing CS was proposed to diminish the quantity of transmissions in sensor networks.Further the energy productivity is a test task for the sensor nodes. However, in previous studies, a clustering approach using hybrid CS for a sensor network and an explanatory model was used to investigate the relationship between beam size and number of transmissions of hybrid CS technology. It uses efficient data integration techniques for large networks, but leads to clone attacks or attacks. Here, a new algorithm called SBEA (Snowball Endurance Algorithm) was proposed and tested with a bow. Thus, you can extend the battery life of your WSN by running effective copy detection. Often, multiple nodes, called observers, are selected to verify the reliability of the nodes within the network. Personal data from the source centre (e.g. personality and geographical data) is provided to the observer at the optional witness stage. The trust and reputation system is used to find the reliability of data aggregation across the cluster head and cluster nodes. It is also possible to obtain a mechanism to perform sleep and standby procedures to improve the life of the sensor node. The sniffers have been implemented to monitor the energy of the sensor nodes periodically in the sink. The proposed algorithm SBEA (Snowball Endurance Algorithm) is a combination of ERCD protocol and a combined mobility and routing algorithm that can identify the cluster head and adjacent cluster head nodes.This algorithm is used to yield the network life time and the performance of the sensor nodes can be increased.

• 정보처리학회논문지C
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• 제17C권6호
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• pp.499-504
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• 2010

플러딩은 무선 네트워크에서 모든 노드들에게 패킷을 전달하는 가장 간단한 방법이다. 하지만, 기본적인 플러딩은 모든 노드가 브로드캐스트 패킷을 한 번씩 전송을 하게 되고, 결과적으로 브로드캐스트 폭풍(broadcast storm) 문제를 일으킨다. 이는 네트워크 자원 및 에너지를 심각하게 낭비시키는 결과를 초래한다. 특히, 무선 센서 네트워크에서는 노드들은 제한된 배터리에 의해 전력을 공급받기 때문에 전력은 가장 중요한 자원 중의 하나이다. 다시 말해, 기본적인 플러딩은 많은 중복 패킷을 생성하기 때문에 전력 소비가 많고, 무선 센서 네트워크의 수명을 단축시키게 된다. 이 브로드캐스트 폭풍 문제를 해결하기 위해서 본 논문에서는 이웃 노드 정보를 이용하여 자식 노드 수와 형제 노드 수에 따른 동적인 확률적 플러딩 기법을 제안한다. 시뮬레이션 결과에서 제안 알고리즘은 기존의 기법들과 비교하여 패킷 발생 수는 유사하게 유지하면서 적은 노드 수에 대해서도 높은 전달율을 보인다.

• ETRI Journal
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• 제37권1호
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• pp.54-60
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• 2015

The use of serial concatenated codes is an effective technique for alleviating the error floor phenomenon of low-density parity-check (LDPC) codes. An enhanced sum-product algorithm (SPA) for LDPC codes, which is suitable for serial concatenated codes, is proposed in this paper. The proposed algorithm minimizes the number of errors by using the failed check nodes (FCNs) in LDPC decoding. Hence, the error-correcting capability of the serial concatenated code can be improved. The number of FCNs is simply obtained by the syndrome test, which is performed during the SPA. Hence, the decoding procedure of the proposed algorithm is similar to that of the conventional algorithm. The error performance of the proposed algorithm is analyzed and compared with that of the conventional algorithm. As a result, a gain of 1.4 dB can be obtained by the proposed algorithm at a bit error rate of $10^{-8}$. In addition, the error performance of the proposed algorithm with just 30 iterations is shown to be superior to that of the conventional algorithm with 100 iterations.

• 조명전기설비학회논문지
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• 제22권2호
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• pp.142-147
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• 2008

제한적인 환경에서 동작하는 무선 센서네트워크 환경에서 가장 중요한 목표 중 하나는 자원의 효율적인 사용을 통한 네트워크의 수명 연장이다. 본 논문에서는 이를 위해 동적인 클러스터헤드 선택 방법과 최단거리 전송기법을 사용하여 효과적인 다중-홉 라우팅 알고리즘을 제안한다. 대표적인 클러스터링 알고리즘인 LEACH 알고리즘과의 비교를 위해 Network Simulator 2을 통해 시뮬레이션 해본 결과, 무선 센서노드의 수명이 최대 37.71[%] 증가하였음을 확인하였다.