• Title/Summary/Keyword: 장기 구조물 건전성 모니터링

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Impedance-based Long-term Structural Health Monitoring for Jacket-type Tidal Current Power Plant Structure in Temperature and Load Changes (온도 및 하중 영향을 고려한 임피던스 기반 조류발전용 재킷 구조물의 장기 건전성 모니터링)

  • Min, Jiyoung;Kim, Yucheong;Yun, Chung-Bang;Yi, Jin-Hak
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.5A
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    • pp.351-360
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    • 2011
  • Jacket-type offshore structures are always exposed to severe environmental conditions such as salt, high speed of current, wave, and wind compared with other onshore structures. In spite of the importance of maintaining the structural integrity for offshore structure, there are few cases to apply structural health monitoring (SHM) system in practice. The impedance-based SHM is a kind of local SHM techniques and to date, numerous techniques and algorithms have been proposed for local SHM of real-scale structures. However, it still requires a significant challenge for practical applications to compensate unknown environmental effects and to extract only damage features from impedance signals. In this study, the impedance-based SHM was carried out on a 1/20-scaled model of an Uldolmok current power plant structure under changes in temperature and transverse loadings. Principal component analysis (PCA) was applied using conventional damage index to eliminate principal components sensitive to environmental change. It was found that the proposed PCA-base approach is an effective tool for long-term SHM under significant environmental changes.

철도교량의 구조건전성 모니터링 시스템 개발

  • Yun, Jeong-Bang;Park, Hyeon-Jun
    • Magazine of the Korean Society of Hazard Mitigation
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    • v.11 no.1
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    • pp.95-98
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    • 2011
  • 최근 국내에서 사회기반시설물에 대한 안전관리 네트워크 통합시스템 구축을 위한 국가핵심과제가 진행되고 있다. 본 연구에서는, 위 과제의 일환으로 진행 중인 철도교량의 구조건전성 모니터링 시스템 구축 및 운용에 대하여 기술하였다. 효율적인 철도교량 모니터링 시스템 구축을 위하여 다양한 종류의 스마트센서가 적용되었으며, 웹 기반의 네트워킹을 통해 외부에서 모니터링 시스템을 원격으로 접속, 제어 할 수 있도록 하였다. 철도교량의 국부 손상을 모니터링 하기 위해 압전센서를 활용한 무선 임피던스 노드를 적용하였고, 구조물 전체의 거동 분석을 위하여 가속도 센서 및 광섬유 센서를 적용하였다. 구조물의 장기 계측을 통한 철도 주행 및 외부 환경에 따른 거동 분석을 수행하였으며, 손상 평가를 위한 신호처리 알고리즘이 적용되었다.

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Web-based Monitoring System for a Railroad Tunnel by Wireless Internet (무선인터넷을 이용한 웹 기반 원격지 철도터널의 계측관리)

  • Lho, Byeong-Cheol;Kim, Jong-Woo;Kim, Jeong-Hoon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.10 no.3
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    • pp.159-164
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    • 2006
  • Mobile communication with wireless modem can be powerful tool in web-based structural health monitoring system in which power and communication method are crucial points. In this study, the major reasons of side cracks in tunnel lining are studied by FEM analysis. In addition, a web-based monitoring system using mobile communication with wireless modem is applied to the tunnel structure to monitor the long term behavior of the side cracks. The field application shows that CDMA is useful method for structural health monitoring system which installed long distance away.

Impedance-based Long-term Structural Health Monitoring for Tidal Current Power Plant Structure in Noisy Environments (잡음 환경 하에서의 전기-역학적 임피던스 기반 조류발전 구조물의 장기 건전성 모니터링)

  • Min, Ji-Young;Shim, Hyo-Jin;Yun, Chung-Bang;Yi, Jin-Hak
    • Journal of Ocean Engineering and Technology
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    • v.25 no.4
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    • pp.59-65
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    • 2011
  • In structural health monitoring (SHM) using electro-mechanical impedance signatures, it is a critical issue for extremely large structures to extract the best damage diagnosis results, while minimizing unknown environmental effects, including temperature, humidity, and acoustic vibration. If the impedance signatures fluctuate because of these factors, these fluctuations should be eliminated because they might hide the characteristics of the host structural damages. This paper presents a long-term SHM technique under an unknown noisy environment for tidal current power plant structures. The obtained impedance signatures contained significant variations during the measurements, especially in the audio frequency range. To eliminate these variations, a continuous principal component analysis was applied, and the results were compared with the conventional approach using the RMSD (Root Mean Square Deviation) and CC (Cross-correlation Coefficient) damage indices. Finally, it was found that this approach could be effectively used for long-term SHM in noisy environments.

Development of Statistical/Probabilistic-Based Adaptive Thresholding Algorithm for Monitoring the Safety of the Structure (구조물의 안전성 모니터링을 위한 통계/확률기반 적응형 임계치 설정 알고리즘 개발)

  • Kim, Tae-Heon;Park, Ki-Tae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.20 no.4
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    • pp.1-8
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    • 2016
  • Recently, buildings tend to be large size, complex shape and functional. As the size of buildings is becoming massive, the need for structural health monitoring(SHM) technique is ever-increasing. Various SHM techniques have been studied for buildings which have different dynamic characteristics and are influenced by various external loads. Generally, the visual inspection and non-destructive test for an accessible point of structures are performed by experts. But nowadays, the system is required which is online measurement and detect risk elements automatically without blind spots on structures. In this study, in order to consider the response of non-linear structures, proposed a signal feature extraction and the adaptive threshold setting algorithm utilized to determine the abnormal behavior by using statistical methods such as control chart, root mean square deviation, generalized extremely distribution. And the performance of that was validated by using the acceleration response of structures during earthquakes measuring system of forced vibration tests and actual operation.

Reliability Evaluation of Fiber Optic Sensors Exposed to Cyclic Thermal Load (주기적인 반복 열하중에 노출된 광섬유 센서의 신뢰성 평가)

  • Kim, Heon-Young;Kang, Donghoon;Kim, Dae-Hyun
    • Journal of the Korean Society for Nondestructive Testing
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    • v.36 no.3
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    • pp.225-230
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    • 2016
  • Fiber Bragg grating (FBG) sensors are currently the most prevalent sensors because of their unique advantages such as ease of multiplexing and capability of performing absolute measurements. They are applied to various structures for structural health monitoring (SHM). The signal characteristics of FBG sensors under thermal loading should be investigated to enhance the reliability of these sensors, because they are exposed to certain cyclic thermal loads due to temperature changes resulting from change of seasons, when they are applied to structures for SHM. In this study, tests on specimens are conducted in a thermal chamber with temperature changes from -$20^{\circ}C$ to $60^{\circ}C$ for 300 cycles. For the specimens, two types of base materials and adhesives that are normally used in the manufacture of packaged FBG sensors are selected. From the test results, it is confirmed that the FBG sensors undergo some degree of compressive strain under cyclic thermal load; this can lead to measurement errors. Hence, a pre-calibration is necessary before applying these sensors to structures for long-term SHM.

Application of High-precision Accelerometer Made in Korea to Health Monitoring of Civil Infrastructures (국산 고정밀 가속도계의 건설 구조물 적용성 평가)

  • Kwon, Nam-Yeol;Kang, Doo-Young;Sohn, Hoon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.29 no.3
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    • pp.277-283
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    • 2016
  • A high-precision force-feedback 3-axes accelerometer developed in Korea has been investigated and studied for the verification of feasibility in the computational analysis and health monitoring of civil infrastructures. Through a series of experiment, the nonlinearity, bandwidth, low-frequency signal measurement accuracy and bias characteristics of the accelerometer has been thoroughly compared to those of two accelerometers produced by two market leaders in domestic and global accelerometer market. The experiment results shows that the overall measurement performance of the accelerometer has superiority over the performance of the two accelerometers from global market leader companies. Especially, the accelerometer shows a better low-frequency signal measurement accuracy and constant bias characteristic, which are mostly required in the computational analysis and the long-term health monitoring of large-scale civil infrastructures.

Design of an Edge Computing System using a Raspberry Pi Module for Structural Response Measurement (구조물 응답측정을 위한 라즈베리파이를 이용한 엣지 컴퓨팅 시스템 설계)

  • Shin, Yoon-Soo;Kim, Junhee;Min, Kyung-Won
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.32 no.6
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    • pp.375-381
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    • 2019
  • Structural health monitoring to determine structural conditions at an early stage and to efficiently manage the energy requirements of buildings using systems that collects relevant data, is under active investigation. Structural monitoring requires cutting-edge technology in which construction, sensing, and ICT technologies are combined. However, the scope of application is limited because expensive sensors and specialized technical skills are often required. In this study, a Raspberry Pi module, one of the most widely used single board computers, a Lora module that is capable of long-distance communication at low power, and a high-performance accelerometer are used to construct a wireless edge computing system that can monitor building response over an extended time period. In addition, the Raspberry Pi module utilizes an edge computing algorithm, and only meaningful data is obtained from the vast amount of acceleration data acquired in real-time. The raw data acquired using Wi-Fi communication are compared to the Laura data to evaluate the accuracy of the data obtained using the system.

Long-Term Measurement of Static Strains of Jacket Type Offshore Structure under Severe Tidal Current Environments (빠른 조류 환경에서의 재킷식 해양구조물 시공 중 및 운영 중 장기 변형률 계측 및 분석)

  • Yi, Jin-Hak;Park, Jin-Soon;Park, Jun-Seok;Lee, Kwang-Soo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.32 no.6A
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    • pp.389-398
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    • 2012
  • In this study, structural strain responses of the jacket-type Uldolmok tidal current power plant structure under severe tidal environments were measured and analyzed using long-term measurement system during construction and also operation. It was observed that there were significant changes in strain responses at the steps of jacket lifting, block loading, pile ejection and insertion. Strains due to dead loads and tidal loads were analyzed before and after removal of a jacket leg, and it was also found that the strains due to dead load were much significantly changed after jacket leg removal. From the measurement data during operation, it was found that strain responses were fluctuated with M2 and M4 tidal periods and also relatively short period of about 10 min due to the peculiar tidal characteristics in the Uldolmok strait. Finally, the neural network-based non-parametric estimation models were investigated to build up the signal-based structural damage monitoring system.

APPLICATION OF BRILLOUIN SCATTERING SENSOR FOR SLOPE MOVEMENT (광 산란파에 의한 사면거동 예측)

  • Chang, Ki-Tae;Lee, Sang-Deok;Yoo, Byung-Sun
    • Journal of the Korean Geophysical Society
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    • v.7 no.4
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    • pp.269-276
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    • 2004
  • Optical fiber sensors have shown a potential to serve real time health monitoring of the structures. They can be easily embedded or attached to the structures and are not affected by the electro-magnetic field. Furthermore, they have the flexibility of the sensor size and very highly sensitive. In this study, we conducted several laboratory and field tests using a novel optical sensor based on Brillouin scattering. One of the advantages of this technique is that the bare fiber itself acts as sensing element without any special fiber processing or preparation. Test results have shown that BOTDR can be a great solution for sensor systems of Civil Engineering Smart Structures.

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