• The KIPS Transactions:PartC
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• v.17C no.6
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• pp.441-450
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• 2010

Recently, a lot of interest is increased in sensor network which gathers various data through many sensor nodes deployed in wired and wireless network environment. However, because of the limitation in memory, computation, and energy of the sensor nodes, security problem is very important issue. In sensor network, not only the security problem, but also computing power should be seriously considered. In this paper, considering these characteristics, we make the sensor network consist of normal sensor nodes and clusterheaders with enough space and computing power, and propose a group key rekeying scheme adopting PCGR(Predistribution and local Collaborationbased Group Rekeying) for secure group communication. In our proposal, we enhance the security by minimizing the risk to safety of the entire network through verifying the new key value from clusterheader by sensor nodes. That is, to update the group keys, clusterheaders confirm sensor nodes through verifying the information from sensor nodes and send the new group keys back to authentic member nodes. The group keys sent back by the clusterheaders are verified again by sensor nodes. Through this mutual authentication, we can check if clusterheaders are compromised or not. Qualnet simulation result shows that our scheme not only guarantees secure group key rekeying but also decreasesstorage and communication overhead.

• The KIPS Transactions:PartC
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• v.16C no.3
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• pp.285-298
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• 2009

According to the development of ubiquitous technologies, sensor networks is used in various area. In particular, medical field is one of the significant application areas using sensor networks, and recently it has come to be more important according to standardization of the body sensor networks technology. There are special characteristics of their own for medical sensor networks, which are different from the one of sensor networks for general application or environment. In this paper, we propose a hierarchical medical sensor networks structure considering own properties of medical applications, and also introduce transmission mechanism based on hierarchical structure. Our mechanism uses the priority and threshold value for medical sensor nodes considering patient's needs and health condition. Through this way Cluster head can transmit emergency data to the Base station rapidly. We also present the new key establishment mechanism based on key management mechanism which is proposed by L. Eschenauer and V. Gligor for our proposed structure and transmission mechanism. We use key provisioning for emergency nodes that have high priority based on patients' health condition. This mechanism guarantees the emergency nodes to establish the key and transmit the urgent message to the new cluster head more rapidly through preparing key establishment with key provisioning. We analyze the efficiency of our mechanism through comparing the amount of traffic and energy consumption with analysis and simulation with QualNet simulator. We also implemented our key management mechanism on TmoteSKY sensor board using TinyOS 2.0 and through this experiments we proved that the new mechanism could be actually utilized in network design.

• The KIPS Transactions:PartC
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• v.14C no.7
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• pp.611-620
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• 2007

Distributing the routing path over the entire network is an important factor to maintain the lifetime of wireless sensor network as long as possible. This paper proposes a fuzzy routing protocol that decides a routing path based on the fuzzy control rules. The fuzzy controller receives the energy values, distances, and hop counts of possible route paths as input, and the inference engine produces the contribution factors for each of route paths. The route path with the largest contribution factor is elected as the final routing path. The nodes contained in the routing path reduce their energy after transmitting a data packet so as to prevent the same route path from being selected repeatedly. It makes the network traffic spreaded over the network resulting longer network lifetime. The computer simulations on TinyOS have shown that the fuzzy routing protocol is more energy efficient and has longer network lifetime compared to the existing routing protocols.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10d
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• pp.372-375
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• 2007

본 논문에서는 이동 노드를 가지는 센서 네트워크와 같은 대규모 애드 혹 네트워크에서 사용 가능한 새로운 라우팅 프로토콜을 소개한다. 본 라우팅 프로토콜은 노드의 이동성을 효율적으로 지원하기 위해 GPS를 이용한 위치정보를 이용하며 가상 싱크 기법을 사용하여 위치정보의 빈번한 플러딩 없이 라우팅을 수행할 수 있도록 설계되었다. V-Geocast는 NS-2 시뮬레이터 환경에서 구현하였으며 단순한 Geocast나 AODV와 같은 기존의 애드 혹 라우팅 알고리즘에 대비하여 뛰어난 성능을 가지는 것을 확인하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.902-905
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• 2010

지형의 상태를 정확히 알 수 없는 타겟 지역에 모바일 센서 네트워크를 구축하는 것은 타겟 지역에 필요한 센서 노드의 수, 유지되어야 할 connectivity, 센서 노드들에 의해 타겟 지역이 coverage 되는 비율을 예측 할 수 없기 때문에 그 효율성을 가늠하기가 어렵다. 본 논문에서 설계한 MSNS(Mobile Sensor Network Simulator)는 GML 문서를 통해 실제 지도상의 개체를 가시화 하고 Map Object의 장애물 여부를 설정하여 타겟 지역을 구성한다. 이를 기반으로 MSNS는 센서 노드의 수와 connectivity degree 그리고 센서 노드들의 센싱/통신/초음파 범위를 입력 받아 센서 노드의 현재 위치 정보, connectivity, 센싱 coverage를 가시화 하여 타겟 지역에 얼마나 많은 노드들이 필요한지 유추할 수 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.839-842
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• 2011

Lately Various researches on energy harvesting techniques for wireless sensor networks have been performed to overcome the power limitation of sensor nodes. In wireless sensor networks with harvesting techniques, sensor nodes exploit environmental energy, such as solar or wind energy, as the power sources of the nodes. Existing energy constrained environment routing protocols may not be suitable for energy harvesting based wireless sensor networks because they do not consider the accumulated energy from harvesting devices. In addition, the paths which aren't dispersed shorten the network lifetime. Therefore, in this paper, the algorithm that the path between each node is dispersed is proposed. In case of using the algorithm to be proposed through the simulator it showed that path of the node is variously reflected.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.1
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• pp.50-54
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• 2016

A Wireless Sensor Network (WSN) is better than a conventional network for use in construction and Operations and Maintenance (O&M) because of its lower surveillance system cost. However, effective operation of a WSN is often difficult to obtain because the surveillance targets are usually fixed inside the building or underground. Therefore, this environmental constraint should be considered in the design of the WSN plant equipment surveillance system prior to installation. This study employs simulations of WSN-based fixed facility surveillance using the TinyOS TOSSIM simulator to investigate ideal types and setups of the WSN. Simulation target protocols included LEACH and flooding and gossiping protocols. The results show that the hierarchically-structured LEACH protocol demonstrated better load-balancing and efficiency than the flatly-structured flooding and gossiping protocol.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.587-590
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• 2019

This paper is about to improve the network life's reduction due to the deviation of sensor node and frequently change of network, the main problem of sensor network. The existing Scalable Topology Organization(STO)-based ZigBee Tree Topology Control Algorithm did not consider ways to consume power so the network lifetime is too short. Accordingly, per each round, electing a new parent node and consisting of the new network topology technique, The Cluster Header Selection, extending the network's overall lifetime. The OMNet++ Simulator yielded results from the existing STO Algorithm and the proposed Cluster Header Selection Technique in the same experimental environment, which resulted in an increase in overall network life by about 40% and an improvement of about 10% in performance in the remaining portion of the battery.

• Journal of the Korea Society for Simulation
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• v.29 no.3
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• pp.73-82
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• 2020

In the fourth industrial revolution, wireless sensor networks (WSNs) are an important element of collecting and analyzing data in a variety of environments without human intervention. This sensor network is greatly affected by topology and routing protocols. Routing protocols, which affect energy consumption, are executed after deploying sensor nodes. Once built, they are difficult to change. Before the WSN is deployed, a routing protocol is carefully selected in view of various environments and the performance of the protocol is evaluated. In this paper, we propose a model to simulate multiple routing protocols using a discrete event system specification (DEVS). The DEVS-based proposed model simulates various situations without changes and structures of the its model as algorithms of the routing protocols are implemented in its coordinators model. To verify normal behaviors of the proposed model, the number of report delivery and the energy consumption of the sensor network were compared using representative protocols LEACH and Dijkstra. As a result, it was confirmed that the proposed model executes normally in both routing protocols.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2005.11a
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• pp.305-308
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• 2005

시각 센서를 이용한 환경 및 상황 인식은 로봇의 자동화된 행동을 위해서 매우 중요하다. 실제 환경에서 사람은 주위를 인식할 때 여러 단계의 인식과정을 거친다. 효율적이고 정확한 환경 인식을 위해서는 지능형 로봇의 인식 또한 사람의 인식과정과 같이 다단계로 이루어져야 한다. 또한 실제 환경은 유동적이며 많은 불확실성을 가지고 있으므로 불확실한 상황에 강인한 인식 방법이 필요하다. 이러한 불확실성을 내포한 환경 및 상황 인식에는 베이지안 네트워크를 이용한 인식이 강인하나 복잡한 환경을 하나의 베이지안 네트워크로 인식하는 것은 어렵다. 이 논문에서는 복잡하고 불확실한 환경 인식을 위한 여러 베이지안 네트워크를 사람의 인식과 같은 다단계의 인식 과정으로 구성된 행동 네트워크 기반으로 결합하는 앙상블 기법을 제안한다. 불확실한 상황을 적용한 환경 실험과 로봇 시뮬레이터를 이용한 로봇 실험으로 베이지안 네트워크 앙상블 기법이 환경 인식에 효과적인 것을 확인할 수 있었다.