• Structural Engineering and Mechanics
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• 제30권2호
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• pp.191-209
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• 2008

A structural monitoring system based on cheap and wireless monitoring system is investigated in this paper. Due to low-cost and low power consumption, micro-electro-mechanical system (MEMS) is suitable for wireless monitoring and the use of MEMS and wireless communication can reduce system cost and simplify the installation for structural health monitoring. For system identification using wireless MEMS, a finite element (FE) model updating method through correlation with the initial analytical model of the structure to the measured one is used. The system identification using wireless MEMS is evaluated experimentally using a three storey frame model. Identification results are compared to ones using data measured from traditional accelerometers and results indicate that the system identification using wireless MEMS estimates system parameters with reasonable accuracy. Another smart sensor considered in this paper for structural health monitoring is Lead Zirconate Titanate (PZT) which is a type of piezoelectric material. PZT patches have been applied for the health monitoring of structures owing to their simultaneous sensing/actuating capability. In this paper, the system identification for building structures by using PZT patches functioning as sensor only is presented. The FE model updating method is applied with the experimental data obtained using PZT patches, and the results are compared to ones obtained using wireless MEMS system. Results indicate that sensing by PZT patches yields reliable system identification results even though limited information is available.

• 한국소음진동공학회논문집
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• 제18권4호
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• pp.458-464
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• 2008

The structural health monitoring has been gaining more importance in civil engineering areas such as earthquake and wind engineering. The use of health monitoring system can also provide tools for the validation of structural analytical model. However, only few structures such as historical buildings and some important long bridges have been instrumented with structural monitoring system due to high cost of installation, long and complicated installation of system wires. In this paper, the structural monitoring system based on cheap and wireless monitoring system is investigated. The use of advanced technology of micro-electro-mechanical system(MEMS) and wireless communication can reduce system cost and simplify the installation. Further the application of wireless MEMS system can provide enhanced system functionality and due to low noise densities. Identification results are compared to ones using data measured from traditional accelerometers and results indicate that the system identification using wireless MEMS system estimates system parameters accurately.

• 한국전자파학회논문지
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• 제21권5호
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• pp.494-500
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• 2010

본 논문에서는 무선광 인식 장치를 새로이 제안하고 실험하였다. 무선광 인식 장치는 리더와 트랜스폰더로 구성되며, 이들은 동일한 구조로서 조명용 LED의 빛을 전송 매체로 사용하고 솔라 셀로 수신하여 서로 정보를 교환한다. 솔라 셀은 수광 표면이 넓고 평면이어서 렌즈를 사용한 광학적 정렬이 필요하지 않기 때문에 구조가 간단하고 사용이 편리하며, 관리 대상 물체의 표면에 부착하기가 용이하다. 또한 무선광 인식 장치는 빛을 전송 매체로 사용하기 때문에 RF 주파수와의 간섭이 없어 안정하다. 실험에서는 솔라 셀을 사용하여 거리가 약 1 m에서 트랜스폰더의 정보를 자동으로 인식하는 무선광 인식 장치를 구현하였다.

• 비파괴검사학회지
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• 제30권3호
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• pp.244-256
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• 2010

Radio frequency identification(RFID) combined with wireless technology has good potential for structural health monitoring(SHM). We describe several advantages of RFID and wireless technologies for SHM, and review SHM examples with working principles, design and technical details for damage detection, heat exposure monitoring, force/strain sensing, and corrosion detection in concrete, steel, carbon fiber reinforced polymer(CFRP), and other materials. Various sensors combined with wireless communication are also discussed. These methodologies can be readily developed, implemented, and customized. There are some technical difficulties, but solutions are being addressed. Lastly, a surface acoustic wave-based RFID system is presented, and possible future trends of SHM based on RFID and wireless technology are presented.

• Smart Structures and Systems
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• 제11권5호
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• pp.533-553
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• 2013

In this paper, system identification of a cable-stayed bridge in Korea, the Hwamyung Bridge, is performed using vibration responses measured by a wireless sensor system. First, an acceleration based-wireless sensor system is employed for the structural health monitoring of the bridge, and wireless sensor nodes are deployed on a deck, a pylon and several selected cables. Second, modal parameters of the bridge are obtained both from measured vibration responses and finite element (FE) analysis. Frequency domain decomposition and stochastic subspace identification methods are used to obtain the modal parameters from the measured vibration responses. The FE model of the bridge is established using commercial FE software package. Third, structural properties of the bridge are updated using a modal sensitivity-based method. The updating work improves the accuracy of the FE model so that structural behaviors of the bridge can be represented better using the updated FE model. Finally, cable forces of the selected cables are also identified and compared with both design and lift-off test values.

• 한국농공학회논문집
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• 제53권5호
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• pp.43-51
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• 2011

Irrigation facilities are spread over demand area in a low density and exposed in the field requiring efficient operation and maintenance. Thus, it could be more efficient to manage an irrigation system when it is with wireless sensor network (WSN) using RFID (Radio Frequency Identification) application. A WSN, a kind of ubiquitous sensor network composed of wireless network, RFID and database management system was developed for agricultural water management in terms of operational status and maintenance requirements. Identification code for RFID tag was designed and an application for RFID reader was developed for field data collection, and a database management system was constructed for managing irrigation facility attributes. The system was installed in I-dong irrigation districts in Gyounggi-province, Korea and the operated results showed the applicability of the WSN for agricultural water management.

• 한국군사과학기술학회지
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• 제16권4호
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• pp.414-421
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• 2013

In this paper, a novel IFF(Identification of Friend and Foe) landmine system has been designed and fabricated using RFID(Radio Frequency Identification) wireless communication system. The IFF landmine system is composed of RECOMS(Remote Controlled Munition System), RFID reader and RFID tag. When the friendly forces have been identified by RFID wireless communication, the IFF landmine is unloaded automatically and indicates the warning message to the operator. Through the discussion, the detailed designs and the test results of identification distance have been described and antenna revision plans for improving the performance have been mentioned.

• 센서학회지
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• 제25권5호
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• pp.337-343
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• 2016

In this paper, we newly introduce a wireless identification system using a solar cell and RF transceivers. The reader sends interrogating signal to a transponder using LED visible light, and the transponder responds to the reader using RF signal. The transponder consists of a solar cell, an amplifier, a microprocessor, and an RF transmitter. The solar cell receives the visible light from the reader and generates current to supply electric power to the other devices in the transponder. At the same time, the solar cell detects interrogating signal in the reader light. The microprocessor senses the interrogating signal and generates a responding signal. The RF transmitter radiates the responding signal to the reader. The transponder is a passive circuit because it operates without external power. In experiments, the maximum read distance between a reader and a transponder was about 1.6 meter.

• 한국통신학회논문지
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• 제37권3C호
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• pp.233-240
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• 2012

일반적인 네트워크를 통한 공장 내 관리와 달리 무선 센서 네트워크를 이용한 공장 내 관리를 위해서는 장치의 발견, 확인, 검증의 과정이 자동으로 수행되어야 한다. 이에 대한 방안으로 본 논문에서는 장치 등록 서버를 제안하고 이를 이용한 관리 시스템을 설계한다. 장치의 발견단계에서는 무선 센서 망에서 사용되는 라우팅 기술의 특성을 이용하고 식별 및 검증 단계에서는 장치를 식별할 수 있는 일반적인 정보를 장치 등록 서버에 저장하여 활용한다. 제안하는 관리 시스템은 구현의 복잡성을 낮추고 여러 종류의 장치들이 분산되어 있는 공장 내에서의 장치 관리를 용이하게 해준다.

• 대한전자공학회논문지TE
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• 제42권1호
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• pp.53-60
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• 2005

본 연구에서는 IEEE 802.11을 기반으로 하는 무선랜 또는 CDMA 기반의 이동전화망을 이용하여 모바일 환경에서 신원조회를 신속하게 할 수 있는 모바일 지문조회시스템을 구현하였다. 구현된 시스템은 크게 PDA를 기반으로 하는 클라이언트와 서버로 구성된다. 클라이언트는 무선통신모듈 및 지문인식모듈을 탑재하고 있는 PDA를 사용하였다. 서버는 데이터베이스와 지문인식모듈을 갖고 있으며 지문 및 신상정보의 등록, 검색 및 검색결과를 클라이언트에 전송하는 기능을 수행하도록 하였다.