• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.7
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• pp.1394-1399
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• 2007

In this paper we propose a Hybrid MAC(HMAC) to enhance the transmission throughput in Wireless Sensor Networks(WSNs). In the proposed HMAC, sender nodes send transmission request packets to the receiver nodes using CSMA/CA MAC protocol. And the receiver node assigns slots according to the network topology and the amount of traffics using TDMA. Using HMAC we get the enhanced throughput by lowering the duplicated slot assignment.

• Structural Monitoring and Maintenance
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• v.2 no.3
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• pp.237-252
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• 2015

This paper addresses the issue of reliability and performance in wireless sensor networks (WSN) based structural health monitoring (SHM), particularly with decentralized damage identification techniques. Two decentralized damage identification algorithms, namely, the autoregressive (AR) model based damage index and the Wiener filter method are developed for structural damage detection. The ambient and impact testing have been carried out on the steel beam structure in the laboratory. Seven wireless sensors are installed evenly along the steel beam and seven wired sensor are also installed on the beam to monitor the dynamic responses as comparison. The results showed that wireless measurements performed very much similar to wired measurements in detecting and localizing damages in the steel beam. Therefore, apart from the usual advantages of cost effectiveness, manageability, modularity etc., wireless sensors can be considered a possible substitute for wired sensors in SHM systems.

• Annual Conference of KIPS
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• 2012.11a
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• pp.755-758
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• 2012

국경 지역을 실시간 모니터링하고, 효율적인 데이터 전달을 위해서는 센서 노드의 에너지 소모를 줄임으로써 전체 네트워크의 수명을 연장시킬 필요가 있다. 그에 따라, 본 논문에서는 네트워크를 클러스터링 기반으로 한 다수의 영역으로 분할하고 각각의 영역 내 특정 노드에 헤드의 역할을 부여하여 라우팅을 수행하는 계층적 클러스터 센서 네트워크를 제안한다. 제안하는 기법에서는 클러스터 헤드에서의 데이터 모음을 통한 통신 메시지 수를 줄임으로써 센서 노드들의 에너지 소모를 최소화시키고, 긴 국경 라인을 커버할 수 있는 충분한 클러스터 확장이 가능하다. 또한 링크의 상태 및 노드의 밀집도를 고려하여 적응적으로 링크의 품질을 측정하는 알고리즘을 제시하여 링크 변화에 대한 빠른 탐색을 통해 네트워크를 관리하는 방안을 제시한다.

• Annual Conference of KIPS
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• 2012.11a
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• pp.698-701
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• 2012

IT기술의 급격한 발전을 토대로 유비쿼터스 사회로 변화함에 따라, USN(Ubiquitous Sensor Network) 기술이 매우 활성화되어있으며 연구 분야로 주목을 받고 있다. 그러나 USN 환경 구축시 효울적인지 실험을 하기위해서는 상당한 시간 및 비용이 따르게 된다. 본 논문에서는 USN 환경을 GML로 구성하고, 장애물에 대해 Map Object 여부 설정을 통해 타겟 지역 설정뿐만 아니라, MSN(Mobile Sensor Node)과 FSN(Fixed Sensor Node)에 대하여 동적 및 다양한 정적 배치가 가능한 멀티형 시뮬레이터인 IS_WSN을 제안한다.

• Annual Conference of KIPS
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• 2012.04a
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• pp.1030-1032
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• 2012

클러스터 기반 라우팅 방법에서 클러스터 헤드에 고장이 발생하면, 전달되지 못하는 센서 데이터가 존재한다. 이를 해결하기 위해 각 클러스터마다 백업 클러스터 헤드를 지정함으로써 원래의 클러스터 헤드에 고장이 발생했을 때 백업 클러스터 헤드가 그 역할을 대신하도록 하는 방법이 연구되고 있다. 백업 클러스터 헤드를 이용한 방법에서는 어떤 노드를 백업 클러스터 헤드로 선출하느냐에 따라 무선센서네트워크의 성능이 좌우된다. 따라서, 본 논문에서는 무선센서네트워크의 에너지 효율성을 높이기 위해 퍼지를 이용하여 각 클러스터의 백업 클러스터 헤드를 선출하는 방법을 제안한다.

• Journal of information and communication convergence engineering
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• v.19 no.3
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• pp.136-141
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• 2021

Research on wireless sensor networks has focused on the monitoring and characterization of large-scale physical environments and the tracking of various environmental or physical conditions, such as temperature, pressure, and wind speed. We propose a stochastic mobility model that can be applied to a MANET (Mobile Ad-hoc NETwork). environment, and apply this mobility model to a newly proposed clustering-based routing protocol. To verify its stability and durability, we compared the proposed stochastic mobility model with a random model in terms of energy efficiency. The FND (First Node Dead) was measured and compared to verify the performance of the newly designed protocol. In this paper, we describe the proposed mobility model, quantify the changes to the mobile environment, and detail the selection of cluster heads and clusters formed using a fuzzy inference system. After the clusters are configured, the collected data are sent to a base station. Studies on clustering-based routing protocols and stochastic mobility models for MANET applications have shown that these strategies improve the energy efficiency of a network.

• Journal of information and communication convergence engineering
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• v.17 no.2
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• pp.105-116
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• 2019

Recently, there has been an increase in research on wireless sensor networks (WSNs) because they are easy to deploy in applications such as internet-of-things (IoT) and body area networks. However, WSNs have constraints in terms of power, quality-of-service (QoS), computation, and others. To overcome the power constraint issues, wireless energy harvesting has been introduced into WSNs, the application of which has been the focus of many studies. Additionally, to improve system performance in terms of achievable rate, cooperative networks are also being explored in WSNs. We present a review on current research in the area of energy harvesting in WSNs, specifically on the application of simultaneous wireless information and power transfer (SWIPT) in a cooperative sensor network. In addition, we discuss possible future extensions of SWIPT and cooperative networks in WSNs.

• International journal of advanced smart convergence
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• v.7 no.4
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• pp.197-205
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• 2018

Nowadays, wireless sensor networks (WSNs) have been widely adopted in structural health monitoring (SHM) systems for social overhead capital (SOC) public infrastructures. Structural health information, environmental disturbances and sudden changes of weather conditions, damage detections, and external load quantizing are among the capabilities required of SHM systems. These information requires an efficient transmission with which an efficient mobility management support for wireless networks can provide. This paper deals with the analysis of mobility management schemes in order to address the real-time requirement of data traffic delivery for critical SHM information. The host-based and network-based mobility management protocols have been identified and the advantages of network mobility (NEMO) enabled Proxy Mobile Internet Protocol version 6 (PMIPv6) have been leveraged in order to address the SHM information transmission needs. The scheme allows an efficient information transmission as it improves the handover performance due to shortened handover latency as well as reduced signaling overhead.

• International Journal of Internet, Broadcasting and Communication
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• v.11 no.1
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• pp.17-26
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• 2019

The Constrained Application Protocol (CoAP) is a specialized web transfer protocol proposed by the IETF for use in IoT environments. CoAP was designed as a lightweight machine-to-machine protocol for resource constrained environments. Due to the strength of low overhead, the number of CoAP devices is expected to rise rapidly. When CoAP runs over UDP for wireless sensor networks, CoAP needs to support congestion control mechanisms. Since the default CoAP defines a minimal mechanism for congestion control, several schemes to improve the mechanism have been proposed. To keep CoAP lightweight, the majority of the schemes have been focused mainly on how to measure RTT accurately and how to set RTO adaptively according to network conditions, but other approaches such as rate-based congestion control were proposed more recently. In this paper, we survey the literature on congestion control for CoAP and discuss the future research directions.

• Journal of Korea Multimedia Society
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• v.21 no.11
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• pp.1288-1296
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• 2018

PBS(Pairwise Broadcast Synchronization) is a well-known synchronization scheme for WSN(Wireless Sensor Networks). As PBS needs the set of node-pairs for network-wide synchronization by over-hearing, GPA(Group-Wise Pair Selection Algorithm) was also proposed after PBS. However, GPA is complex and requires too many message transmissions, leading to much power consumption. Besides, GPA is not appropriate to topology change or mobile wireless sensor networks. So, we propose a new and energy-efficient pair-node selection algorithm for PBS. The proposed scheme's performance has been evaluated and compared with GPA by simulation. The results are shown to be better than GPA.