• Smart Structures and Systems
• /
• 제9권2호
• /
• pp.145-164
• /
• 2012

In this paper, solar-powered, multi-scale, vibration-impedance sensor node on Imote2 platform is presented for hybrid structural health monitoring (SHM) in cable-stayed bridge. In order to achieve the objective, the following approaches are proposed. Firstly, vibration- and impedance-based hybrid SHM methods are briefly described. Secondly, the multi-scale vibration and impedance sensor node on Imote2-platform is presented on the design of hardware components and embedded software for vibration- and impedance-based SHM. In this approach, a solar-powered energy harvesting is implemented for autonomous operation of the smart sensor nodes. Finally, the feasibility and practicality of the smart sensor-based SHM system is evaluated on a full-scale cable-stayed bridge, Hwamyung Bridge in Korea. Successful level of wireless communication and solar-power supply for smart sensor nodes are verified. Also, vibration and impedance responses measured from the target bridge which experiences various weather conditions are examined for the robust long-term monitoring capability of the smart sensor system.

• IEIE Transactions on Smart Processing and Computing
• /
• 제6권2호
• /
• pp.109-116
• /
• 2017

In this paper, we propose an Internet of Things (IoT) platform for ocean observation buoys. The proposed system consists of various sensor modules, a gateway, and a remote monitoring site. In order to integrate sensor modules with various communications interfaces, we propose a controller area network (CAN)-based sensor data packet and a protocol for the gateway. The proposed scheme supports the registration and management of sensor modules so as to make it easier for the buoy system to manage various sensor modules. Also, in order to extend communication coverage between ocean observation buoys and the monitoring site, we implement a multi-hop relay network based on a mesh network that can provide greater communication coverage than conventional buoy systems. In addition, we verify the operation of the implemented multi-hop relay network by measuring the received signal strength indication between buoy nodes and by observing the collected data from the deployed buoy systems via our monitoring site.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2011년도 정기 학술대회
• /
• pp.36-39
• /
• 2011

In this paper, performance of EMI interface and multi-channel wireless impedance sensor node is evaluated for SHM on bolted connection. To achieve the objective, following approaches are implemented. Firstly, an interface washer is designed to monitor loosened bolt through the variation in EMI of interface washer due to change in preload in bolt. Secondly, a multi-channel wireless impedance sensor node based on Imote2 platform is designed for automated and cost-efficient impedance-based SHM on bolted connections. Finally, performance of the multi-channel wireless impedance sensor node and the interface washer are experimentally validated for a lab-scale bolted connection model. A damage monitoring method using RMSD index of EMI signatures is utilized to examine the strength of each individual bolted connection.

• 대한임베디드공학회논문지
• /
• 제2권4호
• /
• pp.242-250
• /
• 2007

Wireless sensor networks are subject to highly heterogeneous system requirements in terms of their functionality and performance due to their broad application areas. Though the heterogeneity hinders the opportunity of developing a single universal platform for sensor networks, efforts to provide uniform, inter-operable and scalable ones for sensor networks are still essential for the growth of the industry as well as their technological advance. As a part of our work to develop such a robust platform, this paper presents the software architecture for sensor nodes with focus on our sensor node operating system and its configuration methodology. Addressing principle issues in its design space which includes programming, execution, task scheduling and software layer models, our architecture is highly reconfigurable with respect to system resources and functional requirements and also highly efficient in supporting multi-threading under small system resources.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제5권2호
• /
• pp.247-268
• /
• 2011

Due to the application-specific nature of wireless sensor networks, the sensitivity to such a requirement as data reporting interval varies according to the type of application. Such considerations require an application-specific, parameter tuning paradigm allowing us to maximize energy conservation prolonging the operational network lifetime. In this paper, we propose a reporting interval adaptive, sensor control platform for energy-saving data gathering in wireless sensor networks. The ultimate goal is to extend the network lifetime by providing sensors with high adaptability to application-dependent or time-varying, reporting interval requirements. The proposed sensor control platform is based upon a two phase clustering (TPC) scheme which constructs two types of links within each cluster - namely, direct link and relay link. The direct links are used for control and time-critical, sensed data forwarding while the relay links are used only for multi-hop data reporting. Sensors opportunistically use the energy-saving relay link depending on the user reporting, interval constraint. We present factors that should be considered in deciding the total number of relay links and how sensors are scheduled for sensed data forwarding within a cluster for a given reporting interval and link quality. Simulation and implementation studies demonstrate that the proposed sensor control platform can help individual sensors save a significant amount of energy in reporting data, particularly in dense sensor networks. Such saving can be realized by the adaptability of the sensor to the reporting interval requirements.

• 제어로봇시스템학회논문지
• /
• 제14권3호
• /
• pp.284-294
• /
• 2008

In this paper, we describe an implementation of small mobile robot that can be used at research and application of mobile sensor networking. This robot that will constitute the sensor network, as a platform of multi-robot system for each to be used as sensor node, has to satisfy restrictions in many aspects in order to perform sensing, communication protocol, and application algorithms. First, the platform must be designed with a robust structure and low power consumption since its maintenance after deployment is difficult. Second, it must have flexibility and modularity to be used effectively in any structure so that it can be used in various applications. Third, it must support the technique of wireless network for ubiquitous computing environment. At last, to let many nodes be scattered, it must be cost-effective and small. Considering the above restrictions of the mobile platform for sensor network, we designed and implemented robots control the current of actuator by using additional circuit for power efficiency. And we chose MSP430 as MCU, CC2420 as RF transceiver, and etc, that have the strength in the aspect of power. For flexibility and modularity, the platform has expansion ports. The results of experiments are described to show that this robot can act as sensor node by RF communication process with Zigbee standard protocol, execute the navigation process with simple obstacle avoidance and the moving action with RSSI(Received Signal Strength Indicator), operate at low-power, and be made with approx. $100.

• 비파괴검사학회지
• /
• 제31권3호
• /
• pp.246-259
• /
• 2011

This study presents a structural health monitoring (SHM) method for bolted connections by using multi-channel wireless impedance sensor nodes and multiple PZT-interfaces. To achieve the objective, the following approaches are implemented. Firstly, a PZT-interface is designed to monitor bolt loosening in bolted connection based on variation of electro-mechanical(EM) impedance signatures. Secondly, a wireless impedance sensor node is designed for autonomous, cost-efficient and multi-channel monitoring. For the sensor platform, Imote2 is selected on the basis of its high operating speed, low power requirement and large storage memory. Finally, the performance of the wireless sensor node and the PZT-interfaces is experimentally evaluated for a bolt-connection model Damage monitoring method using root mean square deviation(RMSD) index of EM impedance signatures is utilized to estimate the strength of the bolted joint.

• 마이크로전자및패키징학회지
• /
• 제29권4호
• /
• pp.55-61
• /
• 2022

다중 암의 동시 진단 기술에 대한 관심이 전 세계적으로 증가하는 추세이며, 진단 난이도를 낮추기 위해 혈액과 같은 미량의 바이오 유체를 이용하여 질병을 진단하는 미세 유체 소자 기반의 액체 생검 기술이 연구되고 있다. 바이오 유체를 이용하여 형광 영상 등을 통해 분석물질의 농도를 측정하는 광학적 바이오 센싱에 있어 민감도를 향상시키기 위한 기술개발이 필요하다. 본 논문에서는 모세관력에 의한 자가구동 기반의 마이크로 채널의 기하학적 구조와 미세 유체 현상만으로 수동적 자기 혈장 분리 기술과 유체 혼합을 통한 분자 인식 활성화 기능을 구현하는 형광 다중 암 진단 센서 플랫폼 구조를 제안하고 설계하였다. 설계된 센서의 혈장 분리부의 성능에 영향을 미치는 파라미터를 확인하기 위해 채널의 수력학적 직경과 종횡비, 유체의 점도를 변수로 설정하여 딘 와류 형성 여부를 시뮬레이션을 통해 확인하였고 최적의 센서 플랫폼 구조를 제시하였다.

• 센서학회지
• /
• 제26권1호
• /
• pp.35-38
• /
• 2017

A thermally responsive hydrogel has reversibility with temperature during swelling. Here, we proposed origami inspired temperature sensor by using multi-layered hydrogel film. The formation of patterned stripes on microscale film drives bending to an angle that can be controlled linearly. Although temperature range was not wide, measured sensitivity of sensors has high resolution and accuracy. It providing a powerful platform for the design of sensitive sensors and that easily adapt other type of sensors in microscale.

• 인터넷정보학회논문지
• /
• 제23권4호
• /
• pp.65-72
• /
• 2022

본 논문에서는 암호 없는(Passwordless) 사용자 환경에서 제로 트러스트(zero trust) 기반 복합 생체 인증을 제안한다. 다양한 FIDO 2.0(Fast Identity Online) 거래 인증 플랫폼 연동을 위한 메타버스와 연계를 설계한다. 특히, 스마트 단말기의 위치정보와 지자기 센서, 가속기 센서 및 복합인증(MFA, Multi-Factor Authentication)을 위한 생체정보 등을 적용한다. 이때, 조도 및 온도/습도 등 상황인식을 바탕으로 2차 인증으로 복잡한 인증을 통해 사용자 환경에 따른 적응형 복합 인증 플랫폼을 제시한다. 그 결과 사용자 환경에 따라 지문인식과 홍채인식, 얼굴인식, 음성 등 행동 패턴으로 다양한 제로 트러스트를 기반으로 2차 사용자 인증이 가능하다. 또한 FIDO 플랫폼의 복합 통합 인증 연계 결과를 확인하고, FIDO2.0을 이용한 거래 인증 연계 플랫폼의 인증 정확도를 개선하고자 한다.