• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.229-230
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• 2009

이 논문은 매립형 FBG 스트레인 센서를 이용하여 고성능콘크리트 시험체의 초기재령시 자기수축에 관하여 연구하였다. Thermocouple 에 의한 FBG 스트레인 센서의 온도보정도 이 논문에서 수행했다. HPC 자기수축량에 대한 배근영향, 크기효과, 온도효과 역시 분석했다.

• 한국공간구조학회논문집
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• 제16권1호
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• pp.85-94
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• 2016

In this study, an acceleration sensor that has optical fibers to measure the inclination and acceleration of a structure through contradictory changes in two-component FBG sensors was examined. The proposed method was to ensure precise measurement through the unification of the deformation rate sensor and the angular displacement sensor. A high sensitivity three-axis accelerometer was designed and prepared using this method. To verify the accuracy of the accelerometer, the change in wavelength according to temperature and tension was tested. Then, the change in wavelength of the prepared accelerometer according to the sensor angle, and that of the sensor according to the change in ambient temperature were measured. According to the test results on the FBG-based vibration sensor that was developed using a high-speed vibrator, the range in measurement was 0.7 g or more, wavelength sensitivity, 2150 pm/g or more, and the change in wavelength change, $9.5pm/^{\circ}C$.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.761-765
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• 2008

This study presents an effective methodology on integrated monitoring system for a maglev guideway using WDM-based FBG sensors. The measuring quantities include both local and global quantities of the guideway response, such as stains, curvatures, and vertical deflections. The strains are directly measured from multiplexed FBG sensors at various locations of the test bridge followed by curvature calculations based on the plane section assumption. Vertical deflections are then estimated using the Bernoulli beam theory and regression analysis. Frequency contents obtained from the proposed method are compared with those from a conventional accelerometer. Verification tests were conducted on the newly-developed Korean Maglev test track. It has been shown that good agreement between the measured deflection and the estimated deflection is achieved. The difference between the two peak displacements was only 3.5% in maximum and the correlations between data from two sensing systems are overall very good. This confirms that the proposed technique is capable of tracing the dynamic behavior of the maglev guideway with an acceptable accuracy. Furthermore, it is expected that the proposed scheme provides an effective tool for monitoring the behavior of the maglev guideway structures without electro magnetic interference.

• 한국항공우주학회지
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• 제30권1호
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• pp.44-48
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• 2002

본 논문에서는 단일 광섬유 FBG/EFPI 복합 센서를 이용하여 변형률, 온도, 그리고 진동으 세 가지 물리량을 동시에 측정하는 방법에 대해 설명하였다. 변형률과 온도를 측정하기 위한 FBG/EFPI 센서 시스템과 진동을 감지하기 위한 EFPI 센서 시스템을 wavelength division multiplexer를 이용하여 하나의 시스템으로 결합하였다. FBG/EFPI 센서 시스템의 광원은 파장 이동 광섬유 레이저(WSFL)이며 EFPI 센서 시스템의 광원은 단파장 레이저 다이오드이다. 구성된 시스템을 이용하여 열챔버에서 알루미늄 보의 열변형률, 온도, 그리고 진동의 동시 측정을 수행하여 본 시스템의 유효성을 확인하였다.

• 항공우주시스템공학회지
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• 제11권1호
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• pp.22-27
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• 2017

본 연구에서 광섬유 브래그 격자 센서를 이용한 보행 진동 측정에 관한 연구를 수행하였다. 보행 진동 측정 시스템의 민감도를 향상시키기 위하여 FBG Seismic sensor 부를 재설계하였다. 성인남성의 평균 걷는 주기 1.5~2.5 Hz를 설계목표인 외부가진 값으로 가정하고, FBG Seismic sensor 부의 1차 모드 고유진동수 값을 외부 가진 주파수 부근 값인 3.5 Hz를 갖도록 CATIA와 ABAQUS를 이용하여 설계하고 제작함으로써 기존의 보행 진동 측정 시스템과 대비하여 민감도를 약 15배 향상 시킬 수 있었고, 침입 감지 분야 적용에 적합함을 확인하였다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.103-106
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• 2004

Impact location monitoring is one of the major concerns of the smart health monitoring. For this application, multipoint ultrasonic sensors are to be employed. In this study, a multiplexed FBG sensor system with wide dynamic range was proposed and stabilization controlling system was also developed for the maintenance of maximum sensitivity of sensors. For the intensity demodulation system of FBG sensors, Fabry-Perot tunable filter(FP-TF) with 23.8nm FSR(free spectral range) was used, which behaves as two separate filters between $1530 \~ 1560$ nm range. Two FBG sensors were attached on the bottom side of the graphite/epoxy composite beam specimen, and low velocity impact tests were performed to detect the one-dimensional impact locations. Impact locations were calculated by the arrival time differences of the impact longitudinal waves acquired by the two FBGs. As a result, multiplexed in-line FBG sensors could detect the moment of impact precisely and found the impact locations with the average error of 1.32mm.

• 전자공학회논문지
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• 제50권3호
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• pp.146-152
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• 2013

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.

• 한국광학회지
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• 제22권2호
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• pp.67-71
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• 2011

본 논문에서는 ultraviolet (UV) 광의 세기를 원격으로 측정하기 위한 아조벤젠 (azobenzene) 코팅된 fiber Bragg grating (FBG)를 구현하였다. 아조벤젠 폴리머는 UV 광에 의해서 탄성이 변화하여 FBG의 코어 격자의 주기 변화를 유도하여 중심파장을 이동시킨다. 중심파장의 이동은 UV 광과 UV 이외의 파장대역의 빛에 의해서 복합적으로 발생하는데 중심파장의 이동량은 약 0.18 nm 이다. 측정의 정확성을 향상시키기 위해서 광원의 복사열에 의한 중심파장의 이동을 열차단 필터(thermal filter)를 사용하여 제거한 결과 중심파장의 이동량은 약 0.06 nm로 다소 감소하였지만 분석 결과 열에 의한 이동량이 충분히 제거된 것을 확인하였다. 또한 서로 다른 방법인 열경화법과 UV 경화법으로 각각 제작된 아조벤젠 폴리머를 이용하여 아조벤젠 코팅 FBG를 제작하였고, 각 제조법에 따른 UV센서로서의 적합성을 확인하였다. 몇 개의 밴드패스 필터(band pass filter)를 사용하여 파장에 대한 민감도를 측정한 결과, 단위 UV 세기당 중심파장의 이동량은 370nm 파장 밴드에서 가장 큰 값인 0.029로, 단파장 영역에서 반응성이 우수하다는 사실을 확인 하였다. 아조벤젠 폴리머의 흡수 스펙트럼과 아조벤젠 코팅 FBG의 파장 의존도가 서로 잘 일치하는 것을 확인하였다.

• Nutrition Research and Practice
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• 제10권1호
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• pp.33-41
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• 2016

BACKGROUND/OBJECTIVES: Diabetes mellitus (DM) is a major chronic disease which increases global health problems. Diabetes-induced renal damage is associated with inflammation and fibrosis. Alpha (AT) and gamma-tocopherols (GT) have shown antioxidant and anti-inflammatory effects in inflammation-mediated injuries. The primary aim of this study was to investigate effects of AT and GT supplementations on hyperglycemia induced acute kidney inflammation in alloxan induced diabetic mice with different levels of fasting blood glucose (FBG). MATERIALS/METHODS: Diabetes was induced by injection of alloxan monohydrate (150 mg/kg, i.p) in ICR mice (5.5-week-old, male) and mice were subdivided according to their FBG levels and treated with different diets for 2 weeks; CON: non-diabetic mice, m-DMC: diabetic control mice with mild FBG levels (250 mg/dl ${\leq}$ FBG ${\leq}$ 450 mg/dl), m-AT: m-DM mice fed AT supplementation (35 mg/kg diet), m-GT: m-DM mice with GT supplementation (35 mg/kg diet), s-DMC: diabetic control mice with severe FBG levels (450 mg/dl < FBG), s-AT: s-DM mice with AT supplementation, s-GT: s-DM mice with GT supplementation. RESULTS: Both AT and GT supplementations showed similar beneficial effects on $NF{\kappa}B$ associated inflammatory response (phosphorylated inhibitory kappa B-${\alpha}$, interleukin-$1{\beta}$, C-reactive protein, monocyte chemotactic protein-1) and pre-fibrosis (tumor growth factor ${\beta}$-1 and protein kinase C-II) as well as an antioxidant emzyme, heme oxygenase-1 (HO-1) in diabetic mice. On the other hands, AT and GT showed different beneficial effects on kidney weight, FBG, and oxidative stress associated makers (malondialdehyde, glutathione peroxidase, and catalase) except HO-1. In particular, GT significantly preserved kidney weight in m-DM and improved FBG levels in s-DM and malondialdehyde and catalase in m- and s-DM, while AT significantly attenuated FBG levels in m-DM and improved glutathione peroxidase in m- and s-DM. CONCLUSIONS: the results suggest that AT and GT with similarities and differences would be considered as beneficial nutrients to modulate hyperglycemia induced acute renal inflammation. Further research with careful approach is needed to confirm beneficial effects of tocopherols in diabetes with different FBG levels for clinical applications.

• 한국소음진동공학회논문집
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• 제17권12호
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• pp.1195-1200
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• 2007

Torque of a rotating shaft has been mostly measured by strain gages combined with either a slip ring or telemetry. However, these methods have severe inherent problems like low S/N ratio, high cost, limited number of channels and difficult installation. In this paper, a new method using FBG(fiber bragg grating) sensors and a rotary optical coupler for online non-contact torque monitoring is suggested. FBG sensor can measure both strain and temperature, and has much batter characteristics than those of a strain gage. A rotary optical coupler is a optical connecting device between a rotating shaft and stationary side without any physical contact. It has been devised for transmitting light between a rotating optical fiber and a stationary optical fiber. The proposed method uses this rotary optical coupler to connect FBG sensors on the rotating shaft to instruments at stationary side. And a reference FBG sensor is also applied to compensate the insertion loss change of the rotary optical coupler due to rotation. Three FBG sensors have been fabricated in a single optical fiber. Two FBG sensors are attached on the shaft surface to measure torque and one sensor is installed at the shaft center to compensate the insertion loss change. The torque of a rotating shaft has been successfully measured by the suggested method proving its superior performance potential.