• 한국해양공학회지
• /
• 제24권3호
• /
• pp.1-10
• /
• 2010

In this study, hybrid smart sensor nodes were developed for the autonomous structural health monitoring of prestressed concrete (PSC) girders. In order to achieve the objective, the following approaches were implemented. First, we show how two types of smart sensor nodes for the hybrid health monitoring were developed. One was an acceleration-based smart sensor node using an MEMS accelerometer to monitor the overall damage in concrete girders. The other was an impedance-based smart sensor node for monitoring the local damage in prestressing tendons. Second, a hybrid monitoring algorithm using these smart sensor nodes is proposed for the autonomous structural health monitoring of PSC girders. Finally, we show how the performance of the developed system was evaluated using a lab-scaled PSC girder model for which dynamic tests were performed on a series of prestress-loss cases and girder damage cases.

• 센서학회지
• /
• 제31권3호
• /
• pp.163-167
• /
• 2022

In this study, we investigated a carbon nanotube (CNT) film sensor to detect hazardous and noxious substances distributed in seawater. The response change of the sensor was studied according to environmental temperature, and its temperature coefficient of resistance (TCR, α) was measured. The temperature of the CNT film (~50 ㎛) was in the range of 20-50 ℃, and αCNT was calculated to be -0.0011 %/ ℃. We experimentally confirmed that the CNT film had a smaller TCR value than that of the conventional sensor. Therefore, we investigated the response change of the CNT sensor according to temperature. The CNT sensor showed a relatively small error of approximately 2.3 % up to 30 ℃, which is within the temperature range of the seawater of the Korean Peninsula. However, when the temperature exceeded 40 ℃, the error in the CNT sensor increased by more than 5.2 %. We fabricated a metal oxide (ITO, indium-tin-oxide) film and compared its performance with that of the CNT sensor. The ITO sensor showed an error of >12.5 % at 30 ℃, indicating that in terms of the stability of the sensor to temperature, the CNT film sensor has superior performance.

• 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.

• 한국해양공학회지
• /
• 제23권6호
• /
• pp.136-145
• /
• 2009

There are two purposes for the marine structures used for fossil fuel: transporting huge amounts of crude oil and petroleum products and producing petroleum resources on the ocean in an isolated operational environment. Both types of structures are exposed to dangerous situations by sea conditions. Such marine structures are greatly affected by ocean climate conditions and its changes. Because of such ocean climate changes, it has been necessary to monitor marine structures. This research discusses the difficulties with adopting a new methodology based on a ubiquitous sensor network and develops an optimized sensor network management system design for a marine structure.

• Journal of Advanced Marine Engineering and Technology
• /
• 제40권4호
• /
• pp.325-329
• /
• 2016

본 연구에서는 Indium-Tin-Oxide 인쇄 박막의 원격 검출이 가능한 해양오염 방제용 센서로서의 응용 가능성에 대해 연구하였다. 우선 양질의 박막제작을 위한 바인더 비율, Indium-Tin-Oxide 중 주석 농도, 열처리 온도 등의 Indium-Tin-Oxide 인쇄박막 제작 조건을 최적화시켰다. 이를 이용하여 전기저항형 액체 센서를 제작하였고, 센서 동작을 확인하기 위하여 대기 중과 해수 중에서 저항 변화를 확인하였다. 이때 저항 변화의 원인은 전해질 속에서 표면에서 일어나는 환원반응에 의한 것으로 해석하였다. 또한 제작된 센서를 Arduino를 사용하여 작동시키고 취득한 데이터의 원격 검출이 가능함을 확인하였다.

• Smart Structures and Systems
• /
• 제7권5호
• /
• pp.393-416
• /
• 2011

Hybrid acceleration-impedance sensor nodes on Imote2-platform are designed for damage monitoring in steel girder connections. Thus, the feasibility of the sensor nodes is examined about its performance for vibration-based global monitoring and impedance-based local monitoring in the structural systems. To achieve the objective, the following approaches are implemented. First, a damage monitoring scheme is described in parallel with global vibration-based methods and local impedance-based methods. Second, multi-scale sensor nodes that enable combined acceleration-impedance monitoring are described on the design of hardware components and embedded software to operate. Third, the performances of the multi-scale sensor nodes are experimentally evaluated from damage monitoring in a lab-scaled steel girder with bolted connection joints.

• 한국항행학회논문지
• /
• 제23권2호
• /
• pp.125-133
• /
• 2019

본 논문에서는 수중에서 광과광센서를 이용하여 AUV의 도킹스테이션에의 도킹에 대한 새로운 연구를 하였다. 이를 위해 LED를 유도광원으로 사용하는 도킹스테이션과렌즈, 광 변위센서, 신호처리기, 연산처리기로 구성된 센서시스템 무인잠수정에 장착한 무인잠수정의 종단유도장치 시스템을 제안하였다. LED 복사광을 이용해 정밀한 상대각도 측정 정밀도를 얻을 수 있도록 집광렌즈 및 광센서 시스템의 원리해석과 이를 검증하기 위해 집광렌즈와 광센서 시스템을 직접 제작하고 기초실험을 수행하였으며 제작한 광학센서를 이용한 AUV와 도킹시스템을 제작하고 수조에서 기본적인 도킹시험을 수행하여 새로운 도킹 방법으로의 가능성을 검증하였다.

• 한국해안·해양공학회논문집
• /
• 제23권1호
• /
• pp.26-33
• /
• 2011

본 연구에서는 항만구조물의 구조건전성 모니터링을 위한 Imote2 센서 플랫폼 기반의 고민감도 스마트 무선센서를 개발하였다. 이를 위해 첫째, 고성능 Imote2 센서 플랫폼을 기반으로 하고, 고민감도 MEMS 가속도계를 탑재한 스마트 무선센서를 설계하였다. 둘째, 스마트 무선센서가 독자적으로 모니터링을 수행할 수 있도록 하는 내장 소프트웨어를 설계하였다. 마지막으로, 개발된 스마트 무선센서의 성능을 모형 케이슨 구조물에서의 실험을 통해 검증하였다.

• 센서학회지
• /
• 제30권4호
• /
• pp.255-260
• /
• 2021

We studied electrochemical sensors using printed carbon nanotube (CNT) film on a polyethylene terephthalate (PET) substrate. Multiwalled CNT films were printed on a PET substrate to study its feasibility as hazardous and noxious substances (HNS) detection sensor. The printed CNT film (PCF) with a 50 ㎛ thickness exhibited a specific resistance of 230 ohm. To determine the optimum sensor structure, a resistance-type PCF sensor (R-type PCF sensor) and a conductive-type PCF sensor (C-type PCF sensor) were fabricated and compared using diluted NH₃ droplets with various concentrations. The response magnitude, response time, sensitivity, linearity, and limit of detection (LOD) were compared, and it was concluded that the C-type PCF sensor exhibited superior performance. By applying a C-Type PCF sensor, we confirmed the detection performance of 12 types of floating HNS and the response of the sensor with selectivity according to the degree of polarity.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2004년도 ICCAS
• /
• pp.1791-1796
• /
• 2004

Recently, great improvements have been made in developing autonomous underwater vehicles (AUVs) using stateof- the-art technologies for various kinds of sophisticated underwater missions. To meet increasing demands posed on AUVs, a powerful on-board computer system and an accurate sensor system with an well-organized control system architecture are needed. In this paper, a new control system architecture is proposed for AUV, ORCA (Oceanic Reinforced Cruising Agent) which is being currently developed by Korea Research Institute of Ships and Ocean Engineering (KRISO). The proposed architecture uses a hybrid architecture that combines a hierarchical architecture and a behavior based control architecture with an evaluator for coordinating between the architectures. This paper also proposed a sensor fusion structure based on the definition of 4 categories of sensors called grouping and 5-step data processing procedure. The development of the AUV, ORCA involving the system architecture, vehicle layout, and hardware configuration of on-board system are described.