• 전기전자학회논문지
• /
• 제22권2호
• /
• pp.289-301
• /
• 2018

IoT 기술을 산업현장에 적용시킨 IIoT는 생산율 향상 및 작업자의 안전을 위한 모니터링의 기술로 이용되고 있다. 하지만 수십에서 수백 대의 공작기계가 부품을 가공하고 있는 생산라인에 Ethernet과 RS485 등을 유선 네트워크를 이용한 IIoT 네트워크의 구축을 통한 모니터링은 기반비용 및 네트워크의 유연성 및 유동성의 문제를 가진다. 이로 인해 유선 네트워크에서 무선 네트워크로의 변화가 필요한 실정이다. 따라서 본 논문에서는 IEEE 802.15.4 표준 무선네트워크 디바이스를 이용하여 생산라인에 Ad-Hoc WSN를 구축한다. 또한 추가적으로 Payload Frame을 모든 센서노드가 공유하는 특징을 가지는 EtherCAT 통신방식을 이용하여 센서노드의 전송주기 및 순서를 설정하였다. 이를 통해 무선 센서 네트워크의 패킷충돌로 인한 신뢰성 저하와 실시간성 문제를 해결했으며 실제 산업현장에 사용할 수 있는 무선 네트워크 라우팅 방식을 확인하였다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2008년도 하계종합학술대회
• /
• pp.1189-1190
• /
• 2008

Wireless sensor networks (WSN) have attracted much attention in recent years due to their potential use in many applications such as border protection and combat field surveillance. Given the criticality of such applications, maintaining a dependable operation of the network is a fundamental objective. However, the resource constrained nature of sensor nodes and the ad-hoc formation of the network, often coupled with an unattended deployment, pose non-conventional challenges and motivate the need for special techniques for dependable design and management of WSN. In this article, we highlight the potential of careful positioning of the base station (BS), which acts as a sink resources.

• International journal of advanced smart convergence
• /
• 제6권3호
• /
• pp.59-64
• /
• 2017

A wireless sensor network is a network in which nodes equipped with sensors capable of collecting data from the real world are configured wirelessly. Because the sensor nodes are configured wirelessly, they have limited power such as batteries. If the battery of the sensor node is exhausted, the node is no longer usable. If more than a certain number of nodes die, the network will not function. There are many wireless sensor network protocols to improve energy efficiency, among which LEACH Protocol is a typical example. The LEACH protocol is a cluster-based protocol that divides sensor space into clusters and transmits and receives data between nodes. Therefore, depending on how the cluster is structured, the shape of the energy cow may decrease or increase. We compare the network lifetimes of the existing LEACH protocols and the three types of protocols that have been improved using fuzzy methods for cluster selection.

• 전자공학회논문지CI
• /
• 제44권3호
• /
• pp.68-73
• /
• 2007

최근 무선센서 네트워크는 센서 영역 안에 수많은 센서 노드로 구성되어 있으며, 각각의 센서들은 강제적인 에너지 구속조건을 가지고 있으므로 효율적인 에너지 관리는 중요하다. WSN 응용 시스템에서 FEC(Forward error correction)는 데이터 전송의 에너지 효율성과 데이터 신뢰성을 증가시킨다. LDPC 코드는 FEC 코드중 하나로 코드워드의 길이가 커지면 다른 FEC 코드 보다 많은 부호화 작업을 필요로 하지만, 샤논의 용량 한계에 접근되어 있으며, 전송에너지의 감소와 데이터 신뢰도를 증가시키는데 사용되어진다. 본 논문에서는 WSN(Wireless Sensor Network)에서의 에너지 효율성 증가와 부호화의 복잡도를 줄이기 위하여 LDPC(Low-density parity-check) 코드의 패리티 체크 행렬의 생성에 Linear-Congruence 방법을 적용하였다. 결과적으로 본 논문에서 제안된 알고리즘은 부호화 에너지 효율성과 데이터의 신뢰도를 증가시켰다.

• 한국인터넷방송통신학회논문지
• /
• 제18권5호
• /
• pp.117-121
• /
• 2018

무선 센서 네트워크는 센서 노드들이 무선으로 구성되어 있는 네트워크이다. 무선으로 구성이 되기 때문에 설치 장소에 제약이 없다. 대신 센서 노드들은 배터리와 같은 제한된 에너지를 가지게 된다. 따라서 네트워크를 오랫동안 유지하려면 에너지 소모를 최소화하여야 한다. 에너지 소모를 최소화하기 위한 여러 프로토콜이 제안되었는데, 그 중 대표적인 프로토콜이 LEACH 프로토콜이다. LEACH 프로토콜은 클러스터 방식 프로토콜로 센서 공간을 클러스터로 나눔으로써 에너지 소모를 최소화한다. 클러스터의 구성에 따라 네트워크 수명이 증가할 수도 있지만, 오히려 수명이 단축될 수도 있다. 본 논문에서는 LEACH Protocol에서 클러스터 헤드 선출 방법을 개선하여 네트워크 수명을 향상시키고자 한다.

• Structural Engineering and Mechanics
• /
• 제49권4호
• /
• pp.509-521
• /
• 2014

In this paper two protocols of Wireless Sensor Networks (WSN) are examined through both a simulation and a case study. The simulation was performed with the optimized network (OPNET) simulator while comparing the performance of the Ad-Hoc on demand Distance Vector (AODV) and the Dynamic Source Routing (DSR) protocols. This is compared and shown with real-world measurement of deflection from eight wireless sensor nodes. The wireless sensor response results were compared with accelerometer sensors for validation purposes. It was found that although the computer simulation suggests the AODV protocol is more accurate, in the case study no distinct difference was found. However, it was shown that AODV is still more beneficial in the field as it has a longer battery life enabling longer surveying times. This is a significant finding as a large factor in determining the use of wireless network sensors as a method of assessing structural response has been their short battery life. Thus if protocols which enhance battery life, such as the AODV protocol, are employed it may be possible in the future to couple wireless networks with solar power extending their monitoring periods.

• 제어로봇시스템학회논문지
• /
• 제15권8호
• /
• pp.867-875
• /
• 2009

A wireless sensor network inherently comprises a plurality of sensor nodes widely deployed for sensing environmental information. To add new functions or to correct some faulty functions of an existing wireless sensor network, the firmware for each sensor node needs to be updated. Firmware update would be quite troublesome if it requires the gathering, reprogramming, and redeploy of all of already deployed sensor nodes. Over-the-air programming (OTA) facilitates the firmware update process, thereby allowing convenient maintenance of an already-deployed sensor network. This paper proposes and implements a remote firmware update mechanism for a TDMA-based wireless sensor network, in which the firmware for sensor nodes constituting the TDMA-based sensor network can be easily updated and the update process can be conveniently monitored from a remote site. We verify the validity of the proposed firmware update method via experiments and introduce three wireless sensor networks installed in outdoor sites in which the proposed firmware update mechanism has been exploited.

• International Journal of Internet, Broadcasting and Communication
• /
• 제7권1호
• /
• pp.62-65
• /
• 2015

Wireless Sensor Network consists of several sensor nodes, these nodes loss some of their energy after the process of communication. So an energy efficient approach is required to improve the life of the network. In case of broadcast network, LEACH protocol uses an aggregative approach by creating cluster of nodes. Now the major concern is to built such clusters over WSN in an optimized way. This work presents the improvement over LEACH protocol. Hence we have different work environments where the network is having different capacities. The proposed work shows how the life time of the network will improve when the number of nodes varies within the network.

• 센서학회지
• /
• 제21권1호
• /
• pp.46-52
• /
• 2012

The rapid water pollution in stream, river, lake and sea in recent years raises an urgent need for continuous monitoring and policymaking to conserve the global clean environment. In particular, the increasing water pollution in coastal marine areas adds to the importance of the environmental monitoring systems. In this paper, the mobile server is designed to gathers information of the water quality at coastal areas. The obtained data by the server is transmitted from field servers to the base station via multi-hop communication in wireless sensor network. The information collected includes dissolved oxygen(DO), hydrogen ion exponent(pH), temperature, etc. By the information provided the real-time monitoring of water quality at the coastal marine area. In addition, wireless sensor network-based flooding routing protocol was designed and used to transfer the measured water quality information efficiently. Telosb sensor node is programmed using nesC language in TinyOS platform for small scale wireless sensor network monitoring from a remote server.

• 조명전기설비학회논문지
• /
• 제29권7호
• /
• pp.62-70
• /
• 2015

The energy of a sensor in a Wireless Sensor Network (WSN) puts a limit on the lifetime of the network. To prolong the lifetime, a clustering plan is used. Clustering technology gets its energy efficiency through reducing the number of communication occurrences between the sensors and the base station (BS). In the distributed clustering protocol, LEACH-like (Low Energy Adaptive Clustering Hierarchy - like), the number of sensor's cluster head (CH) roles is different depending on the sensor's residual energy, which prolongs the time at which half of nodes die (HNA) and network lifetime. The position of the CH in each cluster tends to be at the center of the side close to BS, which forces cluster members to consume more energy to send data to the CH. In this paper, a protocol, pseudo-LEACH, is proposed, in which a cluster with a CH placed at the center of the cluster is formed. The scheme used allows the network to consume less energy. As a result, the timing of the HNA is extended and the stable network period increases at about 10% as shown by the simulation using MATLAB.