• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.379-382
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• 2015

무선 센서 네트워크는 제한된 에너지 자원으로 동작하므로 에너지 소비를 최소화하여 통신하는 기법이 무선 센서 네트워크 설계에 있어 매우 중요한 요소이다. 센서 노드들의 에너지 효율을 개선하기 위한 다양한 방법 중 클러스터링 알고리즘에 기반 한 계층적 라우팅 방법이 무선 센서 네트워크의 성능과 수명을 증가시키기 위해 효과적인 기술임이 알려지면서 다양한 접근법이 제시되고 있다. 클러스터 기반 아키텍처에서 클러스터의 부하 균형을 위한 효율적인 군집 모델은 게이트웨이와 센서 노드의 수명을 증가시켜 전체 네트워크의 성능을 향상 시킨다. 본 논문에서는 네트워크의 수명과 에너지 효율성을 높이기 위해 새로운 부하 균형 군집 모델을 제시한다. 또한 최적해를 보장하는 분기 한정 알고리즘을 설계하고 이를 이용해 다양한 조건에서 기존에 제시된 부하 균형 군집 모델과 실험하고 성능을 비교한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.1263-1266
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• 2004

무선 환경에서의 멀티캐스트 문제는 기존의 유선 환경에서와는 다른 접근방식을 필요로 한다. 기존 유선환경에서의 멀티캐스팅 문제가 링크기반 모델에서 접근을 한 반면 무선환경에서는 노드기반 모델로의 접근 방법이 무선환경의 잇점을 고려하는 것이 된다. 더욱이 게이트웨이나 라우터 등의 기반시설 없이 무선 노드들 만으로 구성된 Ad-hoc 네트워크에서는 멀티캐스트 문제에 추가적인 사항이 고려되어야 하는데 그 대표적인 것 중의 하나가 에너지이다. 보다 짧은 경로의 최단 전달시간 보다. 에너지의 소비를 줄일 수 있는 멀티캐스트 트리의 구성이 더 중요한 경우가 있다. 본 논문에서는 브로드캐스트 트리의 가지치기(prune) 방법을 향상하여 통신으로 인한 전력소비를 줄이는 멀티캐스트 트리 생성 알고리즘을 제안한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.975-977
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• 2009

오늘날 무선 센서 네트워크는 유비쿼터스 인프라 구축 및 각종 응용 서비스를 제공하기 위해 다양한 분야에 설치되어 운용되고 있지만 센서 네트워크 서비스는 특정 사용자에만 제한적으로 제공되고 있다. 센서 데이터들을 효율적으로 전송하고 공유하기 위한 다양한 방법들이 제안되고 있는데, 그 중에서 최근에 이슈가 되는 것이 P2P 네트워크를 활용한 것이다. 하지만 제한된 연산 자원을 가지고 배터리를 사용하는 센서노드를 P2P의 피어(Peer)로 구현하는 것은 현실적으로 매우 힘들다. 본 논문에서는 인터넷에 연결된 게이트웨이 노드에 센서 단위의 가상의 센서 피어를 구축하는 방안을 제안한다. 특히 가상 센서 피어를 생성하기 위한 데이터 처리, P2P 서비스 기술 생성, 가상 피어 관리 기법 등에 관한 상세내용을 기술한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8C
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• pp.633-641
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• 2008

Since WSNs encounter attacks, such as jamming or eavesdropping without physical access occurs, security is one of the important requirements for WSNs. The key pre-distribution scheme that was recently researched for advance of security in WSNs distributes the keys and probability with the use of q-composite random key pre-distribution method, but there is a high probability that no key shared between sensor nodes, and it takes a lot of time and energy to find out the shared key. Therefore, it is not suitable for WSNs. In order to enhance stability of a node that plays a role of gateway without depending on probabilistic key, this paper proposesa key pre-distribution scheme combined with random key pre-distribution scheme and double hash chain. Since the proposed scheme can maintain a small storage place and strong security strengths, it is more efficient than the existing schemes with the same security strengths. In addition, since it uses a small size of key generation key set, it can reduce a great deal of storage overhead.

• Convergence Security Journal
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• v.17 no.5
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• pp.87-92
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• 2017

MANET is a network composed itself because mobile nodes are connected wirelessly. It has been applied to various fields for group communication. However, the dynamic topology by the movement of the nodes causes routing failure frequently because it is difficult to maintain the position information of the nodes participating in the group communication. Also, it has a problem that network performance is decreased due to high overhead for managing information of member nodes. In this paper, we propose a multicast technique using location-based 2-tier virtual group that is flexible and reliable in management of member nodes. The network is composed of cellular zones and the virtual group is constructed using the location information of the nodes in the proposed technique. The virtual group management node is selected to minimize the overhead of location information management for member nodes in the virtual group. In order to improve the reliability for management of member nodes and multicast data transmission, it excludes the gateway node with low transfer rate when setting the route after the packet transmission rate of the member nodes is measured. The excellent performance of the proposed technique can be confirmed through comparative experiments with AMroute method and PAST-DM method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.364-367
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• 2007

We combined CC2431(Chipcon, Norway), as the platform for the Indoor Location Tracking, which follows Zigbee/IEEE802.15.4 standards in RSSI (Received Signal Strength Indicator) and Base Station Node and then, embodied Indoor Location Tracking System. CC2431 is composed of the Reference Node that transfer its current position at the designated place and the Blind Node. The Blind node receives the current position(X and Y coordinates) of the Reference Node fields which are being contiguous and also, calculates its current position and transfers it to the Base Station Node. The base station node is used for receiving the current position of blind node and passing its data to the PC as a gateway. We can make sure where is the Blind Node not only from the out-of-the-way place of the server side but from the outside in a real-time.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.6 no.3
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• pp.461-470
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• 2016

As IoT is broadly used in many fields, the security of IoT is becoming especially important and critical issues. Security and privacy are the key issues for IoT applications, and still faced with some enormous challenges. Sensor has limited resources such as computing power, memory, battery. By means of deeply analyzing the security architecture and features in security framework. While a number of researchers have explored such security challenges and open problems in IoT, there is an unfortunate lack of a systematic study of the security challenges in the IoT landscape. This special issue features recent and emerging advances IoT architecture, protocols, services and applications. The alternative method is IoT security gateway. In this paper, we surveyed the demands and requirements. By means of deeply analyzing the security architecture and features, we analyzed the demands and requirements for security based on gateway application.

• KIISE Transactions on Computing Practices
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• v.24 no.1
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• pp.1-9
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• 2018

Low-power long-range networks (LoRa) has a comprehensive coverage of up to 30 km, so that long-range positioning is possible. However, the position error in the current LoRa environment is over 500 m. This makes it difficult to use practical location services in the LoRa environment. In this paper, we propose a method to improve the position accuracy by correcting an inaccurate visual error when sending a signal from a mobile node to a gateway through the reference node of each zone in the LoRa environment. Experiments were carried out using MATLAB, and a radio propagation algorithm, the Hata model, was used to cancel out the stationary noise and to evaluate the environmental noise. Experimental results showed that the error range decreased as the number of reference nodes increased and a mobile node approach the reference node.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11A
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• pp.1147-1158
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• 2006

Clustering algorithm is an essential element to implement a hierarchical routing protocol, especially for a large-scale wireless sensor network. In this paper, we propose a new type of energy-efficient clustering algorithm, which maximizes the physical distance between cluster head and gateway by a neighbor node discovery mechanism. Furthermore, a slave/master patching scheme is introduced as a useful means of further improving the energy-efficiency. It has been shown that the number of cluster heads can be reduced by as many as 21% as compared with the existing clustering algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3C
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• pp.281-292
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• 2008

A main application of sensor networks are to monitor and to send information about a possibly hostile environment to a powerful base station connected to a wired network. To conserve power from each sensor, intermediate network nodes should aggregate results from individual sensors. However, it can make it that a single compromised sensor can render the network useless, or worse, mislead the operator into trusting a false reading. In this paper, we propose a protocol to give us a key aggregation mechanism that intermediate network nodes could aggregate data more safely. The proposed protocol is more helpful at multi-tier network architecture in secure sessions established between sensor nodes and gateways. From simulation study, we compare the amount of the energy consumption overhead, the time of key transmission and the ratio of of key process between the proposed method and LHA-SP. The simulation result of proposed protocol is low 3.5% a lord of energy consumption than LHA-SP, the time of key transmission and the ration of key process is get improved result of each 0.3% and 0.6% than LHA-SP.