광섬유 산란형 센서를 이용한 사회기반시설물의 보안에 관한 연구

권일범,윤동진,이승석 한국비파괴검사학회 2004 한국비파괴검사학회지 Vol.24 No.5

광섬유 ROTDR (Rayleigh optical time domain reflectometry) 센서와 보다 긴 광섬유를 감지광섬유로 사용할 수 있는 광섬유 BOTDA (Brillouin optical time domain analysis) 센서를 구성하고, 이들 각각을 이용하여 중요보안 대상체인 사회기반시설물에 침투하는 침입자를 탐지할 수 있는 기초 연구를 수행하였다. ROTDR 센서의 감지부로는 넓은 면적을 감지할 수 있는 매설형 광섬유 센서 탐지판을 제작하고, 인가된 침입물체의 위치와 무게에 따른신호특성을 고찰하였다. ROTDR 센서는 펄스 폭이 30 ns이고, 광섬유의 길이는 10 km 이상이다. 위치탐지오차는 약 2m 이내였으며, 무게에 따른 탐지능력은 20 kgf, 40 kgf, 60 kgf, 80 kgf의 네 단계를 구분할 수 있음을 알 수 있었다. 넓은 지역에 걸친 침입자의 침투를 감시하기 위하여 수십 km의 광섬유 길이 전체를 감지부로 사용할 수 있는 광섬유 BOTDA 센서를 개발하였다. BOTDA 센서는 한 개의 레이저 다이오드와 두 개의 광전 변조기(electro-optic modulator)를 사용하여 간단하게 구성하였다. 침입자에 의한 광섬유의 변형률 벽화를 탐지하는 실험을 수행하기 위하여 광학테이블 위에 광섬유에 변형률을 인가하기 위한 실험 장치를 설치하여 실험을 수행하였다. 이 실험으로부터 시간간격 1.5 초동안 광섬유 약 4.81 km의 길이를 거리분해능 3 m로 침입자를 탐지할 수 있음을 확인하였다. We have studied the detection techniques, which can determine the location and the weight of an intruder into infrastructure, by using fiber-optic ROTDR (Rayleigh optical time domain reflectometry) sensor and fiber-optic BOTDA (Brillouin Optical time domain analysis) sensor, which can use an optical fiber longer than that of ROTDR sensor. Fiber-optic sensing plates of ROTDR sensor, which are buried in sand, were prepared to respond the intruder effects. The signal of ROTDR was analyzed to confirm the detection performance. The constructed ROTDR could be used up to 10 km at the pulse width of 30 ns. The location error was less than 2 n1 and the weight could be detected as 4 grades, such as 20 kgf, 40 kgf, 60 kgf and 80 kgf. Also, fiber optic BOTDA sensor was developed to be able to detect intrusion effect through an optical fiber of tens of kilometers longer than ROTDR sensor. Fiber-optic BOTDA sensor was constructed with 1 laser diode and 2 electro-optic modulators. The intrusion detection experiment was peformed by the strain inducing set-up installed on an optical table to simulate a11 intrusion effect. I11 the result of this experiment, the intrusion effect was well detected as the distance resolution of 3 m through the fiber length of about 4.81 km during 1.5 seconds.

가변 페브리-페로 필터와 FBG를 이용한 광세기 기반 자기기준 광섬유 센서

최상진,반재경,Choi, Sang-Jin,Pan, Jae-Kyung 대한전자공학회 2013 전자공학회논문지 Vol.49 No.11

본 논문에서는 자기기준 특성을 가지는 광세기 기반 광섬유 센서 구조를 제안하고 실험적으로 구현하여 성능을 제시한다. 제안하는 광섬유 센서는 광대역 광원(BLS), fiber Bragg grating (FBG), 가변 페브리-페로(Fabry-Perot) 필터, LabVIEW 프로그램으로 구성된다. 제안한 자기기준 광섬유 센서의 이론적인 해석을 통하여 측정 변수(X)와 보정 변수(${\beta}$)를 정의하고, 이를 바탕으로 전달함수(H)를 구한다. 또한 실험을 통하여 이론적인 해석의 타당성을 제시한다. 제안한 광섬유 센서 구조는 광대역 광원의 출력 광세기가 0 dB, 3 dB, 6 dB 감소해도 측정결과에 영향을 미치지 않는 자기기준 특성을 가진다. 또한 다른 특성의 FBG를 사용하여도 측정 가능하므로, 제안한 광섬유 센서 구조는 임의의 규격을 가진 FBG를 사용할 수 있다. 광원의 광세기가 감소하였을 때와 세 가지 다른 특성의 FBG 쌍을 이용하여 측정한 결과 이론적인 값과 잘 일치함을 보였다. 따라서 제안한 광섬유 센서는 자기기준 특성과 구성하는 FBG의 규격이 비교적 엄격하지 않아도 되는 장점을 가진다. In this paper, we have proposed and experimentally demonstrated an intensity-based self-referencing fiber optic sensor. The proposed fiber optic sensor consists of a broadband light source (BLS), fiber Bragg grating (FBG), tunable Fabry-Perot (F-P) filter, and LabVIEW program. We define the measurement parameter (X) and the calibration parameter (${\beta}$) to determine the transfer function(H) of the self-referencing fiber optic sensor, and the validity of the theoretical analysis is confirmed by experiments. The self-referencing characteristic for the proposed system has been validated by showing that the measurement parameter (X) is invariant for BLS optical power attenuations of 0 dB, 3 dB, and 6 dB. Also, the measured result is irrelevant to the FBGs with different characteristics. This means that the proposed fiber optic sensor offers the flexibility for determining the FBGs needed for implementation. Experimental results for the proposed fiber optic sensor are in good agreement with a theoretical analysis for BLS optical power attenuations and for three FBG pairs with different characteristics. So, the proposed fiber optic sensor has several benefits, including the self-referencing characteristic and the flexibility to determine the FBGs.

Applications of fiber optic sensors in civil engineering

Deng, Lu,Cai, C.S. Techno-Press 2007 Structural Engineering and Mechanics, An Int'l Jou Vol.25 No.5

Recent development of fiber optic sensor technology has provided an excellent choice for civil engineers for performance monitoring of civil infrastructures. Fiber optic sensors have the advantages of small dimensions, good resolution and accuracy, as well as excellent ability to transmit signal at long distances. They are also immune to electromagnetic and radio frequency interference and may incorporate a series of interrogated sensors multiplexed along a single fiber. These advantages make fiber optic sensors a better method than traditional damage detection methods and devices to some extent. This paper provides a review of recent developments in fiber optic sensor technology as well as some applications of fiber optic sensors to the performance monitoring of civil infrastructures such as buildings, bridges, pavements, dams, pipelines, tunnels, piles, etc. Existing problems of fiber optic sensors with their applications to civil structural performance monitoring are also discussed.

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.

A novel fiber optic temperature monitoring sensor using hard-polymer-clad fiber and an optical time-domain reflectometer

Kim, Hyeong-Cheol,Lee, Jung-Ryul SAGE Publications 2014 Journal of intelligent material systems and struct Vol.25 No.5

<P>Hard-polymer-clad fiber is a specific type of optical fiber, in which a hard polymer cladding made of fluoroacrylate acts as a protective coating for an inner silica core. An optical time-domain reflectometer is an optical loss measurement system that provides optical loss and event distance measurement in real time. This study proposes a novel fiber optic temperature monitoring sensor system using an economical optical time-domain reflectometer and hard-polymer-clad fiber. Sensor nodes were economically and quickly made by locally stripping hard-polymer-clad fiber clad through photothermal and photochemical processes using a continuous/pulse hybrid-mode laser. The core length exposed was easily controlled by adjusting the laser beam diameter, and the exposed core created a backscattering signal in the optical time-domain reflectometer attenuation trace. The backscattering peak was sensitive to the temperature variation. Since the elaborated hard-polymer-clad fiber temperature sensor was insensitive to strain applied to the sensor node and to temperature variation in the normal hard-polymer-clad fiber line, neither strain compensation nor isolation technique is required. These characteristics are important advantages for using as structure-integrated temperature sensors. The performance characteristics of the sensor nodes included an operating range of up to 120 °C, a resolution of 1.52 °C, a tensile strain resistance of 13%, and a temperature sensitivity of −0.01 dB/°C.</P>

Length Effects of Hetero-Core Optical Biosensor based on Evanescent Field Absorption

심준환,손경락,찬주광 한국항해항만학회 2008 한국항해항만학회지 Vol.32 No.9

Sensing performances of evanescent field absorption (EFA) hetero-core fiber sensor has been presented based on EFA by changing the length and the core diameter of the single mode fiber. Experimental results have demonstrated a good feature in their relationship between the length and the core diameter of the single mode fiber. The sensor consists of 2 fiber optics which have the same cladding diameter of 125 ㎛. However one fiber optic used is single mode and has varying core diameter ranging from 3.3 to 5.6 ㎛. The other fiber is multimode type and has a thicker fixed core diameter of 62.5 ㎛. The 2 fiber optics are thermally spliced together. Experiments conducted to measure the resonance wavelength were carried out over a range of refractive index, to find the optimum sensing length. Experiments show that core diameter of the single mode fiber and sensing length affects the linearity and sensitivity. Sensing performances of evanescent field absorption (EFA) hetero-core fiber sensor has been presented based on EFA by changing the length and the core diameter of the single mode fiber. Experimental results have demonstrated a good feature in their relationship between the length and the core diameter of the single mode fiber. The sensor consists of 2 fiber optics which have the same cladding diameter of 125 ㎛. However one fiber optic used is single mode and has varying core diameter ranging from 3.3 to 5.6 ㎛. The other fiber is multimode type and has a thicker fixed core diameter of 62.5 ㎛. The 2 fiber optics are thermally spliced together. Experiments conducted to measure the resonance wavelength were carried out over a range of refractive index, to find the optimum sensing length. Experiments show that core diameter of the single mode fiber and sensing length affects the linearity and sensitivity.

Detection of Low Frequency Signals using Interferometric Fiber Sensors based on Phase Generated Carrier Demodulation Technique

Wang Yong-jiao,Wang Chuan,Yuan Yin-quan,Liang Lei 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.2

A fiber-optic sensor is a sensor with high sensitivity, and signal detection technology is one of its key technologies. Phase generated carrier demodulation technology is a homodyne demodulation method widely used for interference fiber-optic sensors. Research reveals that the amplitude of the interference signal and the modulation depth will affect the result of demodulation. The distortion of the demodulated signal can be reduced by the elimination of the effects of the interference signal amplitude and modulation depth. A phase generated carrier demodulation method for interference fiber-optic sensors is proposed to detect weak ELF signals. Theoretical analysis and simulation have been implemented on the demodulation of weak ELF signals using low-level sub-mixer carrier. The results indicate that in the demodulation of weak ELF signals, DC drift occurs in the DCM approach, while the Arctangent approach does not have this problem. Then, an optical fiber sensing system for ELF signals is established based on optical fiber interferometer, indicating the Arctangent approach is able to demodulate the VLF signals accurately.

Hopper lens type WDM을 이용한 광섬유 Dual Sensor 외곽경보시스템 설계 및 제작 연구

김경복(Kyung Bok Kim) 대한전자공학회 2018 전자공학회논문지 Vol.55 No.10

본 논문에서는 최근 광섬유를 이용한 센서가 산업 전부에 널리 활용되고 있다. 더욱이 광섬유의 광학적인 특성을 이용하여 감시 및 경보 시스템 분야에도 관련기술이 비약적인 발전을 이루고 있다. 본 연구에서는 국내최초로 Hopper Lenz type WDM을 이용한 광섬유 dual sensor 외곽감시용 경보 시스템 시제품을 개발하여 특성을 평가하였다. 개발된 외곽감시용 경보 시스템 시제품은 파장이 1310nm 특성의 경강선이 삽입된 광섬유 line sensor와 사용파장이 1550∼1555nm에서 최적의 특성이 나타나는 FBG 광섬유 압력센서를 동일 구간의 철조망 감지부 광 케이불에 적용하였다. 그 결과 기존의 OTDR방식의 광 경보시스템보다 감지 신호의 정확성과 다중점 신호를 검출하는 효과를 나타내었다. 감지 구간도 종전의 시스템보다 1.5배 향상 되었다. 검출된 신호는 경고음을 알리는 알람시스템과 고해상도의 ITV 시스템과 연동된다. 개발된 시스템은 향후 유사 경보시스템의 수입대처 시스템으로 가능하며, 그 외 중요 산업현장에서 보안 감시용으로 적용될 수 있고, 국가 주요설비나 시설의 감시용도로 사용될 수 있다. In this paper, recently, as if the rapidly developing of optical fiber sensor is widely used all round the industries. Furthermore, The related technology of an optical fiber perimeter warning and guard system using optical characteristics make rapid progress. In this study, we have develop an optical fiber perimeter warning system carried dual sensor using hopper lens type WDM in making prototype and its characteristics were evaluated for the first time in korea. we used its and applied an optical fiber line sensor insert wire by heart treatment processing of 1310nm in wavelength and FBG optical fiber pressure sensor of 1550∼1555nm in wavelength in order to take advantage of wire fence. In result, A fabricated prototype showed each of higher accuracy and detected multi-point signal compared with OTDR method system. we have improved 1.5 of detected distance compared with its. we have connected alarm system and ITV of good. especially, we can expect the utilization of all round the industries and national infrastructure and facilities base for security. therefore we can expect its deal with income in the future.

온도 모니터링을 위한 광섬유 센서와 온도센서 배열 케이블의 비교 연구

김중열,김유성,송윤호 한국지반공학회 2007 한국지반공학회논문집 Vol.23 No.4

Two kinds of temperature monitoring technology have been introduced in this study, which can measure coincidently temperatures at many points along a single length of cable. One is to use a thermal sensor cable comprizing of addressable thermal sensors. The other is to use an optic fiber sensor with Distributed Temperature Sensing (DTS) system. The differences between two technologies can be summarized as follows: A thermal sensor cable has a concept of “point sensing” that can measure temperature only at a predefined position. The accuracy and resolution of temperature measurement are up to the capability of the individual thermal sensor. On the other hand, an optic fiber sensor has a concept of “distributed sensing” because temperature is measured practically at all points along the fibre optic cable by analysing the intensity of Raman back-scattering when a laser pulse travels along the fiber. Thus, the temperature resolution depends on the measuring distance, measuring time and spatial resolution. The purpose of this study is to investigate the applicability of two different temperature monitoring techniques in technical and economical sense. To this end, diverse experiments with two techniques were performed and two techniques are applied under the same condition. Considering the results, the thermal sensor cable will be well applicable to the assessment of groundwater flow, geothermal distribution and grouting efficiency within about 200m distance, and the optic fiber sensor will be suitable for long distance such as pipe line inspection, tunnel fire detection and power line monitoring etc.

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.