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REACH: An Efficient MAC Protocol for RF Energy Harvesting in Wireless Sensor Network
Kim, Teasung,Park, Joohan,Kim, Jeehyeong,Noh, Jaewon,Cho, Sunghyun WILEY INTERSCIENCE 2017 WIRELESS COMMUNICATIONS AND MOBILE COMPUTING Vol.2017 No.-
<P>This paper proposes a MAC protocol for Radio Frequency (RF) energy harvesting in Wireless Sensor Networks (WSN). In the conventional RF energy harvesting methods, an Energy Transmitter (ET) operates in a passive manner. An ET transmits RF energy signals only when a sensor with depleted energy sends a Request-for-Energy (RFE) message. Unlike the conventional methods, an ET in the proposed scheme can actively send RF energy signals without RFE messages. An ET determines the active energy signal transmission according to the consequence of the passive energy harvesting procedures. To transmit RF energy signals without request from sensors, the ET participates in a contention-based channel access procedure. Once the ET successfully acquires the channel, it sends RF energy signals on the acquired channel during Short Charging Time (SCT). The proposed scheme determines the length of SCT to minimize the interruption of data communication. We compare the performance of the proposed protocol with RF-MAC protocol by simulation. The simulation results show that the proposed protocol can increase the energy harvesting rate by 150% with 8% loss of network throughput compared to RF-MAC. In addition, the proposed protocol can increase the lifetime of WSN because of the active energy signal transmission method.</P>
Rogue Access Point Detection Using Peripheral Beacon Frame Cyclical Fingerprint in Real-time
Jeehyeong Kim,Jaewon Noh,Joohan Park,Sunghyun Cho 대한전자공학회 2017 대한전자공학회 학술대회 Vol.2017 No.1
We propose a method to detect a rogue AP without any additional hardware in real-time. Differences beacon frame cycles between the access AP and other peripheral APs can be used to determine whether or not a rogue AP exists. Also, we describe how to find numerically the rogue APs. By using Mahalanobis distance, we show that it is possible to seperate them because normal beacon frames are distributed in the range 0 to 0.5, and rogue beacon frames are over the range 1.8 to 2.2.
IoT 플랫폼 기반 디지털 트윈 프로토타입 설계 및 구현
김지형(Jeehyeong Kim),최원기(Wongi Choi),송민환(Minhwan Song),이상신(Sangshin Lee) 한국방송·미디어공학회 2021 방송공학회논문지 Vol.26 No.4
With the recent development of IoT and artificial intelligence technology, research and applications for optimization of real-world problems by collecting and analyzing data in real-time have increased in various fields such as manufacturing and smart city. Representatively, the digital twin platform that supports real-time synchronization in both directions with the virtual world digitized from the real world has been drawing attention. In this paper, we define a digital twin concept and propose a digital twin platform prototype that links real objects and predicted results from the virtual world in real-time by utilizing the oneM2M-based IoT platform. In addition, we implement an application that can predict accidents from object collisions in advance with the prototype. By performing predefined test cases, we present that the proposed digital twin platform could predict the crane’s motion in advance, detect the collision risk, perform optimal controls, and that it can be applied in the real environment.