• 전기학회논문지P
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• 제56권1호
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• pp.56-62
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• 2007

In this paper, design method for power tower hazard diagnosis/predition system based on UsN was proposed. The proposed method used multi-hybrid sensors to measure rotation, displacement, and inclination state of power tower, and made decision/prediction of hazard of power tower. System design was made with requirement analysis of monitoring for transmission power facility and use of MEMS and optic fiber sensors. For hazard decision, analysis of correlation was made using sensor output. LN based on IEC61850,international standard for digital substation, was also proposed. For transmission facility monitoring, digital substation and power tower were considered as parts of power facility networks.

• 대한전자공학회논문지SD
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• 제41권6호
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• pp.53-58
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• 2004

광기능성 색소가 분산된 평면도파로 결합기와 측면연마된 광섬유를 이용한 자외선 센서를 제작하여 광강도 변화에 따른 감도특성을 측정하였다. 광변색성 색소인 스파이록사진이 분간된 폴리머를 평면도파로로 사용하였다. 조사되는 자외선의 강도와 시간에 의해 유효굴절률이 변화하는 성질을 이용하였다. 자외선 조사시간을 3 초와 5 초로 고정한 상태에서 자외선 조사강도를 점차 증가시켰을 때 센서감도가 자각 $1.21{\mu}W/mw$와 $2.75{\mu}W/mw$로 나타났다. 자외선 조사 강도에 따른 출력 광강도의 변화를 측정한 결과 자외선 강도가 클수록 출력 광강도도 증가하고 포화시간은 단축됨을 알 수 있었다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.17-20
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• 2005

In-situ structural health monitoring of filament wound pressure tanks were conducted during water-pressurizing test using embedded fiber Bragg grating (FBG) sensors. We need to monitor inner strains during working in order to verify the health condition of pressure tanks more accurately because finite element analyses on filament wound pressure tanks usually show large differences between inner and outer strains. Fiber optic sensors, especially FBG sensors can be easily embedded into the composite structures contrary to conventional electric strain gages (ESGs). In addition, many FBG sensors can be multiplexed in single optical fiber using wavelength division multiplexing (WDM) techniques. We fabricated a standard testing and evaluation bottle (STEB) with embedded FBG sensors and performed a water-pressurizing test. In order to increase the survivability of embedded FBG sensors, we suggested a revised fabrication process for embedding FBG sensors into a filament wound pressure tank, which includes a new protecting technique of sensor heads, the grating parts. From the experimental results, it was demonstrated that FBG sensors can be successfully adapted to filament wound pressure tanks for their structural health monitoring by embedding.

• 한국소음진동공학회논문집
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• 제16권12호
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• pp.1279-1285
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• 2006

In this study, structural deformation estimation using displacement-strain relationship is investigated. When displacements of a structure cannot be measured directly, estimation of displacements using strain data can be an alternative solution. Additionally, the deformation of the whole structure as well as the displacement at the point of interest can be estimated. Strain signals are obtained front Fiber Bragg Grating(FBG) sensors that have an excellent multiplexing ability. Some experiments were performed on two beams and a plate to which FBG sensors were attached in the laboratory. Strain signals from FBG sensors along a single strand of optical fiber were obtained through wavelength division multiplexing(WDM) method. The beams and the plate structures were subjected to various loading conditions, and deformed shapes were reconstructed from the displacement-strain transformation relationship. The results show good agreements with those measured directly from laser sensors. Moreover, the whole structural shapes of the beams and the plate were estimated using only some strain sensors.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1748-1750
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• 2004

This paper deals with the detection method of the Quench phenomenon for superconducting magnet using the Acoustic Emission (AE) sensor. AE sensor is the elements, which is used to change the Acoustic signal to the voltage value. This signal may be used to detect whether the superconducting magnet has been at the Quench state or not. Recently, the development of the Quench detection technique, which is the using voltage and current signals, fiber-optic sensor, and so on, for the superconducting applications is widely studying. This method for the Quench detection of the superconducting magnet is also studying at some kinds of institute in Japan and the united state. Because of the large-scale superconducting magnet like International Thermonuclear Experimental Reactor(ITER) is charged a lot of energy, when the Quench phenomenon is being at the superconducting magnet it is happen to the problem of the protection for the applications. In this paper, we concluded that the Quench detection was possible when the mechanical stress by means of the local heat is generated at the part of inside superconducting magnets.

• 한국해양공학회지
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• 제19권2호
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• pp.82-89
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• 2005

This study deals with the development of the extended Kalman filter(EKF) algorithm for the localization of underwater mining vehicles. Both simulation and experimental studies in a test bed are carried out. For the experiments, a scale dawn tracked vehicle is run in a soil bin containing cohesive soil of bentonite-water mixture. To develop the EKF algorithm, we use a kinematic model including the inner/outer track slips and the slip angle for the vehicle. The measurements include the inner and outer wheel speeds from encoders, the heading angle from a compass sensor and a fiber optic rate gyro, and x and y coordinate position values from a vision system. The vision sensor replaces the LBL(Long Base Line) sonar system used in the real underwater positioning situations. Artificial noise signals mimicking the real LBL noise signal are added to the vision sensor information. To know the mean slip values of the tracks in both straight and cornering maneuver, several trial running experiments are executed before applying the EKF algorithm. Experimental results show the effectiveness of the EKF algorithm in rejecting the sensor measurements noise. Also, the simulation and experimental results show close correlations.

• 대한토목학회논문집
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• 제40권6호
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• pp.547-553
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• 2020

노후화 시설물의 증가에 따라 선제적 유지관리의 중요성은 점차 증대되고 있다. 선제적 유지관리는 시설물의 응답 계측으로부터 시작되기 때문에 높은 정밀도를 가지는 응답을 획득하는 것이 중요하다. 국부적인 응답 중 변형률은 균열 감지 및 피로 진전 예측 등에 활용가능하다. 변형률 센서는 크게 이산형 및 분포형 센서로 구분된다. 이산형 센서의 대표적인 예가 광섬유 브래그 격자(FBG)와 전기 저항식 게이지이다. 이산형 센서는 높은 정확성과 재현성(고 정밀)을 가지지만, 측정점이 제한된다는 한계를 가진다. 브릴루앙 산란 기반 광섬유 변형률 계측 시스템 중 하나인 Brillouin Optical Correlation Domain Analysis (BOCDA)은 대표적인 분포형 센서이며, 5 cm 라는 높은 공간 분해능을 가진다. BOCDA는 투영된 광원에서 발생하는 산란파를 이용하여 광섬유 전 구간의 변형률을 계측한다. 측정점이 많아지는 장점이 있으나, 이산형 센서에 낮은 정확도와 재현성을 가진다. 본 연구에서는 고 정밀 데이터(이산형 센서)와 저 정밀 데이터(분포형 센서) 각각의 장점을 융합하는 후처리 기법을 제안하였으며, 이에 대한 가능성을 검증 실험을 통해 확인했다.

• 대한기계학회논문집A
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• 제41권4호
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• pp.313-319
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• 2017

광섬유 센서는 전자기 간섭에 독립적이고 원거리 계측이 가능하여 다양한 분야에 적용되고 있다. 특히, 광섬유 브래그 격자(FBG) 센서는 다중화, 절대측정이 가능하여 구조 건전성 모니터링(SHM)을 위해 널리 사용되고 있다. 일반적으로, FBG 센서는 에폭시와 같은 접착제를 이용하여 구조물에 직접 부착 및 모듈 제작을 통해 적용한다. 하지만, 에폭시로 부착된 FBG 센서 기반의 장시간 모니터링 과정에서 신호 변화가 발생하여 보정이 요구된다. 이는 계절적 요인으로써 장시간 온도 변화 환경에 노출되어 센서의 접착구조 변형에 의한 결과이며, 센서 접착제의 열경화 과정에 대한 규명이 필요하다. 본 연구에서는, 패키징 방식 4가지 경우의 FBG 센서 시편을 제작하고, 반복 열하중 시험을 수행하였다. 시험 결과, 상온경화 과정에서 미소한 잔류 압축 변형률이 발생하였고, 반복 열하중 초기단계에서 수백 ${\mu}{\varepsilon}$의 압축 변형률이 인가되어 유지되었다. 이를 통해 FBG를 이용한 장시간 SHM을 위해서는 FBG 센서의 신호에 대한 안정화 과정이 필요함을 확인하였다.

• 한국의학물리학회지:의학물리
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• 제21권1호
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• pp.29-34
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• 2010

본 연구에서는 치료용 양성자선 계측을 위한 광섬유 방사선량계 개발을 목적으로 최적화 과정의 기초연구를 통하여 광섬유 방사선량계를 제작하였다. 양성자선 계측의 최적화를 위해 유기섬광체의 종류에 따른 섬광량 및 브래그 피크의 피크/플래투를 측정하여 가장 효율이 뛰어난 섬광체를 선별하였고, 유기섬광체의 직경에 따라 물 팬텀의 각 깊이에서 손실되는 양성자선의 에너지에 대해 유기섬광체에서 발생되는 섬광량을 측정하여 유기섬광체의 직경에 따른 선형성을 도시하고 최적의 섬광체 직경을 선택하였다. 또한 양성자선의 조사각도에 대해 유기섬광체의 길이에 따른 섬광량 및 섬광량의 표준편차를 측정하여 입사각 의존도를 판별하고 최적의 섬광체 길이를 결정하였다. 최적화 과정을 통하여 제작된 센서 성능평가의 일환으로 양성자 가속기의 선량율 및 모니터 유닛에 따른 광섬유 방사선량계의 섬광량을 측정하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.86-95
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• 2006

Brillouin backscatter is a type of reflection that occurs when light is shone into an optical fibre. Brillouin reflections are very sensitive to changes in the fibre arising from external effects, such as temperature, strain and pressure. We report here several case studies on the measurement of strain using Brillouin reflections. A mechanical bending test of an I beam, deployed with both fiber optic sensors and conventional strain gauge rosettes, was performed with the aim of evaluating: (1) the capability and technical limit of the DTSS technology for strain profile sensing; (2) the reliability of strain measurement using fiber optic sensor. The average values of strains obtained from both DTSS and strain gauges (corresponding to the deflection of I beam) showed a linear relationship and an excellent one-to-one match. A practical application of DTSS technology as an early warning system for land sliding or subsidence was examined through a field test at a hillside. Extremely strong, lightweight, rugged, survivable tight-buffered cables, designed for optimal strain transfer to the fibre, were used and clamped on the subsurface at a depth of about 50cm. It was proved that DTSS measurements could detect the exact position and the progress of strain changes induced by land sliding and subsidence. We also carried out the first ever distributed dynamic strain measurement (10Hz) on the Korean Train eXpress(KTX) railway track in Daejeon, Korea. The aim was to analyse the integrity of a section of track that had recently been repaired. The Sensornet DTSS was used to monitor this 85m section of track while a KTX train passed over. In the repaired section the strain increases to levels of 90 microstrain, whereas in the section of regular track the strain is in the region of 30-50 microstrain. The results were excellent since they demonstrate that the DTSS is able to measure small, dynamic changes in strain in rails during normal operating conditions. The current 10km range of the DTSS creates a potential to monitor the integrity of large lengths of track, and especially higher risk sections such as bridges, repaired track and areas at risk of subsidence.