구조물의 정적 및 동적 거동 모니터링을 위한 광섬유 기반 하이브리드 신경망 계측 시스템

박영수,송광용,진승섭,박영환,김성태 한국구조물진단유지관리공학회 2020 한국구조물진단유지관리공학회 논문집 Vol.24 No.2

Various studies have been conducted on the structural health monitoring using optical fiber. Optical fibers can be used to measure multiple and distributed strain. Among the optical fiber sensors, FBG sensor has advantages of dynamic response measurement and high precision, but the number of measurement points is limited. Distributed fiber sensors, represented by distributed Brillouin sensors, usually have more than 1000 measurement points, but the low sampling rate makes dynamic measurements impossible. In this study, a hybrid nerve sensor system using only the advantages of the FBG sensor and the distributed Brillouin sensor has been proposed. Laboratory experiments were performed to verify the proposed system, and the accuracy and reproducibility were verified by comparing with commercial sensors. Applying the proposed system, dynamic response ambient measurements are used to evaluate the global state of the structure. When an abnormal condition is detected, the local condition of the structure is evaluated by static response measurement using the distributed measurement system. The proposed system can be used for efficient structural health monitoring. 광섬유를 이용한 구조물 건전도 모니터링은 다양한 연구가 이루어졌다. 광섬유는 다중 및 분포로 변형률을 계측 할 수 있다. 광섬유 센서 중, FBG 센서는 동적 응답 계측과 정밀도가 높은 장점이 있지만, 계측 포인트의 제한이 있다. 분포형 광섬유 센서는 계측 포인트가 1000개가 넘지만, 샘플링 속도가 낮아 동적 계측이 불가능하다. 본 연구에서는 FBG와 브릴루안 상관영역 측정법의 장점만을 이용한 하이브리드 신경망 센서 계측 시스템이 제안하였다. 광섬유 브래그 격자를 포함한 광섬유를 이용하여 정적응답과 동적 응답을 선택적으로 계측 할 수 있는 계측 시스템이다. 제안된 시스템검증을 위하여 실내 실험을 수행하였으며, 기존의 센서와의 비교를 통해 정확도와 재현성을 검증하였다. 제안된 시스템을 활용하여, 동적 응답을 상시 계측하고, 전역적인 구조물의 상태를 평가한다. 이상 상태가 감지 되면, 분포형 계측 시스템을 이용하여 정적 응답을 계측하여, 구조물의 국부적인 상태를 평가한다. 제안된 시스템을 통해 효율적인 구조물 건전도 모니터링에 활용될 수 있을 것으로 판단된다.

Method and application of spatial positioning for valid temperature-measuring optical fibers in concrete dams

Huawei Zhou,Chunju Zhao,Zhipeng Liang,Yihong Zhou,Fang Wang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.8

Spatial positioning of Valid Temperature-measuring Optical Fiber (VTOF) is of great significancefor accurately grasping the real temperature distribution of a concrete dam. However, there is barely an effective way to accurately locate the measuring points of optical fiber in concrete dams. A comprehensive data symmetry analysis technique is presented for determining the optimal spatial positioning of valid temperature-measuring optical fibers (VTOFs) in concrete dams. This approach includes a mathematical model to confirm the center of symmetry in monitoring data, which is required to reconstruct the real spatial temperature distribution. This process can identify VTOF locations and verify the reliability of temperature predictions. Experimental validation was conducted using findings from research on a new mathematical model, site measurements from a concrete dam, and corresponding data from distributed optical fibers. These results were successfully applied to the construction of the Baihetan dam; the concrete temperature from 405 pouring blocks in 5 typical dam monoliths was accurately monitored, and the temperature-measuring points of VTOFs were more than 24711. Meanwhile, the optical fiber temperature measurement and temperature field analysis system of Baihetan dam located in southwest China was developed based on accurately acquired temperature measurement data, which provides data basis and engineering application platform support for temperature evolution and temperature field analysis and precise temperature control management of pouring blocks.

광섬유 센서를 이용한 실시간 온도 감시 시스템

이창근(Chang-Kun Lee),김영수(Young-Su Kim),구명모(Myeong-Mo Gu),김봉기(Bong-Gi Kim) 한국컴퓨터정보학회 2010 韓國컴퓨터情報學會論文誌 Vol.15 No.12

본 광 분포 온도 측정 시스템은 광섬유 자체를 온도 측정용 센서로 이용하는 시스템으로, 한 가닥의 광섬유만을 포설하여 포설된 주변 전체 온도를 수 천 점으로 측정이 가능한 시스템이다. 분포 측정의 경우 측정 점의 수를 많이 할 경우 측정점당 비용을 기존 센서의 비용 수준으로 절감 할 수 있으며 동시에 한 두 가닥의 광섬유로 전체 센서를 연결 할 수 있는 장점이 있다. 본 논문에서는 일반적으로 통신용으로 사용하는 광케이블 자체를 센서 (optical sensor cable)로 활용하여 최소한 매 1m 간격으로 센서 기능을 할 수 있는 특성을 이용함으로써 각 센서와 수많은 연결선들을 줄이고 시스템은 컴퓨터를 이용하여 데이터저장, 제어나 보관 등 데이터 관리가 용이하며, 실시간 온도 변화에 따른 온도 이력정보를 이용한 실시간 온도 모니터링 시스템을 구축한다. Optical Temperature Distribution Sensor Measurement System uses fiber optic sensors itself for temperature measurement is a system which can be measured the Installed surrounding entire temperature as a thousand points by laying a single strand of fiber optic. If there are a lot of measuring points in the distribution Measurement, the cost of each measuring point can be reduced the cost level of existing sensors and at the same time this has the advantage of connecting all sensors as one or two strands of fiber. Generally Optical Fiber is used for communication but Optical Fiber itself can be used for sensor and it has the characteristic of sensor function which can be measured Temperature in the at least each one meter distance. By using these characteristics each sensor and the number of Connection Lines can be reduced. In this paper, we implement a real time temperature monitoring system, which is easy to manage and control for data storage, data management, data storage using a computer and which has the functions of monitoring and correction according to Real-time temperature changes using historical temperature data.

대형 구조물의 변형률 측정을 위한 광섬유 TR-EFPI 센서의 개량

권일범 ( Kwon¸ Il-bum ),최만용 ( Choi¸ Man-yong ),김치엽 ( Kim¸ Chi-yeop ) 한국구조물진단유지관리공학회 2000 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.4 No.2

The sensor for continuous in-situ monitoring is better to be embedded in large structures. Fiber optic sensors can be embedded in the structures to get the health information in the structures. Fiber optic EFPI(extrinsic Fabry-Perot interferometric) sensors had been shown in many publications which concerned about the structural strain measurement. However, the gage lengths of the sensors in these papers were limited at about 1 cm because it is very difficult to make the long gage length fiber optic EFPI sensor. If the gage length of the fiber optic EFPI sensor could be made as long as about 90 mm, then the sensitivity is to be more higher than the short gage length fiber sensor at about 9 times. In this study, the fiber optic TR-EFPI (total reflected - extrinsic Fabry-Perot interferometric) sensor was developed and was improved to be get the long gage length about 90 mm. The loading-unloading test was performed to confirm the performance of the improved fiber optic TR-EFPI sensor. In this experiment, the strain which was determined by the fiber optic signal had some errors. It was considered that this errors caused by the sliding mismatch in the sensor probe.

플라스틱 광섬유를 이용한 호흡센서의 개발

유욱재,백지윤,조동현,장경원,서정기,허지연,이봉수,조영호,박병기,문주현,Yoo, Wook-Jae,Baek, Ji-Yun,Cho, Dong-Hyun,Jang, Kyoung-Won,Seo, Jeong-Ki,Heo, Ji-Yeon,Lee, Bong-Soo,Cho, Young-Ho,Park, Byung-Gi,Moon, Joo-Hyun 대한의용생체공학회 2009 의공학회지 Vol.30 No.6

In this study, we fabricated a plastic optical fiber based sensor which can monitor the respiration of a patient. The circumference changes of the abdomen were measured using a mirror, a light source and optical detectors because the circumferences of the abdomen could be varied with respiration. The intensity of the reflected lights were measured according to the changes of distance between mirror and plastic optical fiber connected to a light source and a photodiode-amplifier system using a Y-coupler. The respiration signals of fiber-optic sensor system were compared with those of the respiratory and temperature transducers of the $BIOPAC^{(R)}$ system. It is expected that a fiber-optic respiration sensor could be developed for real time respiration monitoring during MRI procedure based on this study.

A Study on Displacement Measurement by A Laser Interferometry using Common-path Fiber-optical Devices

Lee, Seok-Soon,Lee, Dong-Wook,Park, Min-Hyeok,Choi, Jin-Gyu,Nam, Kwang-Sik,Zhao, Shang The Society for Aerospace System Engineering 2014 International Journal of Aerospace System Engineer Vol.1 No.1

A displacement measurement system that uses fiber-optical common-path interferometry has been developed. The system includes fiber-optic devices and a collimator attached to a linear translation stage. The interferometry effect was detected with a photodetector whose signal was measured on an oscilloscope. Experiments showed that vibration of the stage disturbed the signal by causing nanoscale interference. Under stable conditions, the measured distance was the almost the same as the value calculated from the linear translation stage parameters.

A Measurement Method for Dispersion in Optical Fiber Communication with Long Distance

Xue-zhao Zheng 보안공학연구지원센터 2014 International Journal of Future Generation Communi Vol.7 No.6

With the development of the telecommunication, optical fiber has been widely used. It has the characteristics of long distance transmission and large capacity, but it also has dispersion exists. The dispersion can be divided into some types. Mode dispersion plays a major role in multimode fiber, while chromatic dispersion or intramodal dispersion are the main mechanism in single mode fiber. Generally, it is quite important to test the dispersion and know the dispersion characteristics. The theoretical basis and experimental device, which are both based on the interference principle, have been introduced in detail. The device is used to measure the fiber dispersion characteristics of optical fiber and the results shows the validity of the theory and the designed test device.

대변위 측정을 위한 다중화된 광섬유 센서

유정애 ( Jung Ae Yoo ),권일범 ( Il Bum Kwon ),조재흥 ( Jae Heung Jo ),서대철 ( Dae Cheol Seo ) 한국센서학회 2005 센서학회지 Vol.14 No.3

A multiplexed bend loss type single-mode fiber-optic sensor system was prepared to measure the displacement of several cm of the civil engineering structures such as many bridges, tunnels and various buildings. This bend loss type fiber-optic sensor used the signal difference between two reflection signals due to various bend losses generating at a pair of optical connectors by using OTDR (optical time domain reflectometer) for measuring displacements. And the experiments were conducted for showing the measurement feasibility on the range of 10 cm, and the multiplexing experiments were also performed to measure the displacements of 5 measuring positions of an object by setting these 5 fiber-optic sensors on a single mode fiber simultaneously.

광커넥터의 반사를 이용한 다중화된 굽힘 손실형 단일모드 광섬유 변위센서

유정애,조재흥,권일범,Yoo Jung-Ae,Jo Jae Heung,Kwon Il-Bum 한국광학회 2004 한국광학회지 Vol.15 No.5

교량과 각종 건물을 비롯한 대형 토목 구조물에서 발생하는 수 mm의 변위를 한 개의 광섬유로 간편하게 측정하기 위하여 광커넥터에서 반사가 굽힘 손실에 의하여 변하는 현상을 이용한 새로운 다중화된 광섬유 변위센서를 제안하고 실험하였다. 한 쌍의 광커넥터 양끝에서 반사광의 신호차이가 두 광커넥터 사이에서 발생한 굽힘 변위에 의해서 달라지는 것을 Optical Time Domain Reflectometer로 측정하여 선형으로 그 변화가 측정되는 변위센서를 만들고, 이 센서 4개를 직렬형으로 배열하여 여러 지점의 변위를 동사에 측정이 가능한 다중화 센서 시스템을 구성하고 실험하였다. 그 결과 이 변위센서를 이용하면 4개 지점에서 각각 최대 6 mm까지의 변위를 6%의 오차범위 내에서 0.9942의 선형성을 가지고 변위를 측정할 수 있음을 확인하였다. We propose and present a new multiplexed bend loss type single-mode fiber-optic sensor system for displacement measurement in order to measure the displacement of several mm of civil engineering structures such as bridges and buildings. We make a bend loss type fiber-optic sensor for measuring displacements using the signal difference between two reflection signals due to various bend losses generating at a pair of optical connectors by using the optical time domain reflectometer. And we fabricate a multiplexed bend loss type fiber-optic sensor detecting linear displacements of 4 measuring positions of an object by setting these new 4 fiber-optic sensors on a single mode fiber simultaneously. We find that the multiplexed fiber-optics displacement sensor has linearity of 0.9942, maximum displacement of 6 mm, and accuracy of 6% for 4 measuring points.

광섬유를 이용한 표면 미세형상 기상 측정

강진호(Jin-Ho Kang),주재영(Jea-Young Joo),이선규(Sun-Kyu Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11

The purpose of process measurement and metrology in manufacturing is to examine whether the machined parts were made according to the designer’s specification. On-machine measurement (OMM) is becoming more and more important for production technology. With no time lost between machining and inspection, such a process will reduce the need for repeating alignment, thus improving the productivity, allowing errors to be corrected quickly. The goal of this research is to evaluate the feasibility of OMM using fiber-optic as a technology to enable measurement for a micro topography. While a wide variety of techniques are available to evaluate machined surface, measurement using fiber-optic is much better suited to OMM. When we apply fiber-optic to OMM, it can make measurement system very compact and robust against disturbance such as external shock or vibration.