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IoT 디바이스의 연결성 향상을 위한 동적 leaf 모드 기반의 INFRA-RPL
홍석원,유성은,Seokwon Hong,Seong-eun Yoo 대한임베디드공학회 2023 대한임베디드공학회논문지 Vol.18 No.4
RPL (IPv6 Routing Protocol for Low-power Lossy Network) is a standardized routing protocol for LLNs (Low power and Lossy Networks) by the IETF (Internet Engineering Task Force). RPL creates routes and builds a DODAG (Destination Oriented Directed Acyclic Graph) through OF (Objective Function) defining routing metrics and optimization objectives. RPL supports a leaf mode which does not allow any child nodes. In this paper, we propose INFRA-RPL which provides a dynamic leaf mode functionality to a leaf node with the mobility. The proposed protocol is implemented in the open-source IoT operating system, Contiki-NG and Cooja simulator, and its performance is evaluated. The evaluation results show that INFRA-RPL outperforms the existing protocols in the terms of PDR, latency, and control message overhead.
배터리 셀의 부피 팽창 감지용 PVdF-HFP/BTO 압전 센서 기반 압력 감지 시스템 설계
홍석원(Seokwon Hong),배지현(Jihyun Bae),이병선(Byoung-Sun Lee) 한국세라믹학회 2024 세라미스트 Vol.27 No.1
Piezoelectric sensor can be used to inform the battery safety by detecting the battery swelling induced pressure. In this study, a piezoelectric sensing material, sensor unit, and sensing system were developed using piezoelectric polymer polyvinylidene fluoride-co-hexafluoropropylene(PVdF-HFP) and piezoelectric ceramic BaTiO3(BTO). Free-standing PVdF-HFP/BTO composite nanofiber web was retrieved as the sensing material due to the nanofiber web-based flexibility and the molecular arrangement driven piezoelectric performances. The PVdF-HFP/BTO composite nanofiber web-based sensor was employed in the automatic pressure sensing system, which provides the visual and audible signals once the pressure exceeds a certain limit. Our work demonstrates that the design of new piezoelectric sensing system is a fruitful pathway to sensing the battery malfunctions.