• 센서학회지
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• 제21권1호
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• pp.46-52
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• 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.

• 한국통신학회논문지
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• 제36권12B호
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• pp.1708-1721
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• 2011

최근 구제역과 같은 가축질병으로 인한 살 처분된 가축매몰지의 적절한 모니터링 시스템의 필요성이 대두되고 있다. 그러나 현재 사용되는 모니터링 시스템은 살 처분된 매몰지 현장에서의 시료를 채취한 후 1~2주간의 모니터링 기간을 필요로 함으로 실시간 감시가 필요로 하는 매몰지에 대한 연속측정이 불가능하다. 이에 본 논문에서는 이런 실시간 모니터링을 가능하게 하는 우선 센서네트워크 기반의 가축매몰지 환경정보 모니터링 시스템 설계 및 구현을 제안한다. 제안된 시스템의 무선 센서노드는 환경센서(Dust, Co2, NH3, H2s, Temperature, Humidity)와 위치확인을 위한 GPS센서로 구성된다. 제안된 시스템은 게이트웨이를 통해 원격지 서버에 전송된 매몰지 환경정보를 분석함으로 언제 어디에서나 유해환경 모니터링이 기능하고 위치확인을 통한 상황에 따른 능동적인 대응을 가능케한다. 따라서 제안된 시스템의 유효성 검증을 위해 규정된 가스 배출관에 센서를 설치하였고, 통합 모니터링이 가능한 테스트 베드에서 실시간으로 수신된 데이터를 수집, 분석하여 시간의 변화에 따른 매몰지 위치의 악취환경변화를 모니터링 하였다. 이를 통한 상황에 따른 실시간 대응을 함으로 유사시 환경오염의 사전예방이 가능 한 것을 확인할 수 있었다.

• Smart Structures and Systems
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• 제6권3호
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• pp.183-196
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• 2010

Monitoring and economical design of alternative energy generators such as wind turbines is becoming increasingly critical; however acquisition of the dynamic output data can be a time-consuming and costly process. In recent years, low-cost wireless sensors have emerged as an enabling technology for structural monitoring applications. In this study, wireless sensor networks are installed in three operational turbines in order to demonstrate their efficacy in this unique operational environment. The objectives of the first installation are to verify that vibrational (acceleration) data can be collected and transmitted within a turbine tower and that it is comparable to data collected using a traditional tethered system. In the second instrumentation, the wireless network includes strain gauges at the base of the structure. Also, data is collected regarding the performance of the wireless communication channels within the tower. In both turbines, collected wireless sensor data is used for off-line, output-only modal analysis of the ambiently (wind) excited turbine towers. The final installation is on a turbine with embedded braking capabilities within the nacelle to generate an "impulse-like" load at the top of the tower. This ability to apply such a load improves the modal analysis results obtained in cases where ambient excitation fails to be sufficiently broad-band or white. The improved loading allows for computation of true mode shapes, a necessary precursor to many conditional monitoring techniques.

• 한국컴퓨터정보학회논문지
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• 제12권6호
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• pp.307-312
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• 2007

무선 센서 네트워크 기술은 유비쿼터스 컴퓨팅의 핵심 분야로서 그 활용도가 다양해 이와 관련된 많은 연구 개발이 이루어지고 있다. 무선 센서 네트워크는 매우 작은 크기의 독립된 무선 센서들을 물리적 공간에 배치하여 주위의 온도, 빛, 가속도 등의 정보를 무선으로 감지, 관리할 수 있는 기술이다. 본 논문에서는 무선 센서 네트워크의 지속적 환경 데이터 처리의 효율성 및 다중 질의의 처리 성능을 높이기 위해 공간색인 기법을 이용한 다중 질의 색인 처리를 제안, 구현하였다. 다중 질의 색인 시스템은 미리 정의된 다중 질의를 이용하여 색인 구조를 생성하고, 센서 네트워크에서의 센서 데이터를 입력으로 받아서 생성된 색인 구조를 통해 센서 데이터가 해당되는 질의를 출력해 주는 시스템이다. 시스템 구축을 위한 무선 센서 노드로서 Mote 플랫폼 중에서 MICAz와 운영체제인 TinyOS를 이용하여 환경 정보를 탐지하고 다중 질의 색인 처리하였다.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.689-709
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• 2010

In this paper, a low cost, low power but multifunctional wireless sensor node is presented for the impedance-based SHM using piezoelectric sensors. Firstly, a miniaturized impedance measuring chip device is utilized for low cost and low power structural excitation/sensing. Then, structural damage detection/sensor self-diagnosis algorithms are embedded on the on-board microcontroller. This sensor node uses the power harvested from the solar energy to measure and analyze the impedance data. Simultaneously it monitors temperature on the structure near the piezoelectric sensor and battery power consumption. The wireless sensor node is based on the TinyOS platform for operation, and users can take MATLAB$^{(R)}$ interface for the control of the sensor node through serial communication. In order to validate the performance of this multifunctional wireless impedance sensor node, a series of experimental studies have been carried out for detecting loose bolts and crack damages on lab-scale steel structural members as well as on real steel bridge and building structures. It has been found that the proposed sensor nodes can be effectively used for local wireless health monitoring of structural components and for constructing a low-cost and multifunctional SHM system as "place and forget" wireless sensors.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 춘계학술대회 논문집
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• pp.63-68
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• 2003

For effective conservation of ocean and harbor, long-term and systematic development of the ocean and harbor monitoring system is essential. The monitoring system capable of real-time and accurate data acquisition is necessary for dealing with contamination such as red tide and the flood. This paper introduces the effective and economical real-time harbor environmental monitoring system that utilizes PCS wireless data communication technology. The monitoring system has various functions such as multiple communication, TCP/IP protocol for wireless internet access, system time synchronization, bi-directional communication between the measuring device and the server. The system has been implemented at Shinseondae harbor pier in Busan to validate the systems stability and effectiveness in data acquisition. The acquired real-time ocean and harbor environmental data is expected to have a large effect, when shared by public through internet.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.731-748
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• 2010

Impact detection and health monitoring are very important tasks for civil infrastructures, such as bridges. Piezoceramic based transducers are widely researched for these tasks due to the piezoceramic material's inherent advantages of dual sensing and actuation ability, which enables the active sensing method for structural health monitoring with a network of piezoceramic transducers. Wireless sensor networks, which are easy for deployment, have great potential in health monitoring systems for large civil infrastructures to identify early-age damages. However, most commercial wireless sensor networks are general purpose and may not be optimized for a network of piezoceramic based transducers. Wireless networks of piezoceramic transducers for active sensing have special requirements, such as relatively high sampling rate (at a few-thousand Hz), incorporation of an amplifier for the piezoceramic element for actuation, and low energy consumption for actuation. In this paper, a wireless network is specially designed for piezoceramic transducers to implement impact detection and active sensing for structural health monitoring. A power efficient embedded system is designed to form the wireless sensor network that is capable of high sampling rate. A 32 bit RISC wireless microcontroller is chosen as the main processor. Detailed design of the hardware system and software system of the wireless sensor network is presented in this paper. To verify the functionality of the wireless sensor network, it is deployed on a two-story concrete frame with embedded piezoceramic transducers, and the active sensing property of piezoceramic material is used to detect the damage in the structure. Experimental results show that the wireless sensor network can effectively implement active sensing and impact detection with high sampling rate while maintaining low power consumption by performing offline data processing and minimizing wireless communication.

• Journal of electromagnetic engineering and science
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• 제15권2호
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• pp.104-110
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• 2015

As civil infrastructures continue to deteriorate, the demand for structural health monitoring (SHM) has increased. Despite its outstanding capability for damage identification, many conventional SHM techniques are restricted to huge structures because of their wired system for data and power transmission. Although wireless data transmission using radio-frequency techniques has emerged vis-$\grave{a}$-vis wireless sensors in SHM, the power supply issue is still unsolved. Normal batteries cannot support civil infrastructure for no longer than a few decades. In this study, we develop a magnetic resonance-based wireless power transmission system, and its performance is validated in three different mediums: air, unreinforced concrete, and reinforced concrete. The effect of concrete and steel rebars is analyzed.

• Smart Structures and Systems
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• 제5권6호
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• pp.663-679
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• 2009

The use of Micro-Electro-Mechanical Systems (MEMS) accelerometers in geotechnical instrumentation is relatively new but on the rise. This paper describes a new MEMS-based system for in situ deformation and vibration monitoring. The system has been developed in an effort to combine recent advances in the miniaturization of sensors and electronics with an established wireless infrastructure for on-line geotechnical monitoring. The concept is based on triaxial MEMS accelerometer measurements of static acceleration (angles relative to gravity) and dynamic accelerations. The dynamic acceleration sensitivity range provides signals proportional to vibration during earthquakes or construction activities. This MEMS-based in-place inclinometer system utilizes the measurements to obtain three-dimensional (3D) ground acceleration and permanent deformation profiles up to a depth of one hundred meters. Each sensor array or group of arrays can be connected to a wireless earth station to enable real-time monitoring as well as remote sensor configuration. This paper provides a technical assessment of MEMS-based in-place inclinometer systems for geotechnical instrumentation applications by reviewing the sensor characteristics and providing small- and full-scale laboratory calibration tests. A description and validation of recorded field data from an instrumented unstable slope in California is also presented.

• 한국해양공학회지
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• 제10권4호
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• pp.160-165
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• 1996

This paper introduces a sea environmental monitoring system for measuring pH,DO, level and temperature. This system is developed using a personal computer(PC) and multiple single board computers. A PC communicates with the single board computers by awireless communication method and transfers data to another personal computer for processing data by a modem. The values of pH,Do,level and temperature, which are basic components to estimate sea environment, are real-timely processed in the single board computer at each stations, and transferred to the monitoring PC. These data are graphically shown on the PC monitor and logged on the data processing system in the form of file. Using the wire and wireless communication system, user can constantly analyze the acquired data and detect the sea contamination.