• 대한전자공학회논문지SD
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• 제41권10호
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• pp.57-62
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• 2004

단일 모드 광섬유의 측면을 일부분 연마하여 연마된 상부에 열 광학 폴리머 층과 금속열선을 형성한 광섬유형 전류센서를 보고한다. 금속 열선에 인가된 전류에 의해서 발생하는 저항열은 폴리머 층의 굴절률을 변화시키고 광섬유의 소산장을 통한 광 감쇄를 유도하게 된다 두 가지 유형의 센서구조를 제안하였고 전류센서로서의 특징을 조사하였다.

• 센서학회지
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• 제15권4호
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• pp.263-268
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• 2006

We have demonstrated a highly sensitive temperature sensor using an etched single mode fiber with a thermally expanded core region. Large core size of thermally expanded core facilitates access to evanescent wave by the wet etching. The etched region was surrounded by a low dispersive external medium with high thermo-optic coefficient. Due to the large difference between the dispersion property of the fiber and that of the external medium, the device reveals a cut-off properties at spectral region. The cut-off wavelength was shifted by the variations of the environmental temperatures because of thermo-optic effect of the external medium. The sensitivity of the fabricated device was found to be $45nm/^{\circ}C$.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.876-879
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• 2004

The buried fiber optic cable as a distributed intrusion sensor for detecting and locating intruders along the long perimeters is proposed. Phase changes resulting from either the pressure of the intruder on the ground immediately above the buried fiber or from seismic disturbances in the vicinity are sensed by a phase-sensitive optical time-domain reflectometer. Light pulses from a Er:fiber cw laser with a narrow, <3kHz-range, spectral width and a frequency drift of < 1 MHz/min are injected into one end of the fiber, and the backscattered light from the fiber is monitored with a photodetector. Results of preliminary studies, measurement of phase changes produced by pressure and seismic disturbances in buried fiber optic cables and simulation of ${\varphi}-OTDR$ response over long fiber paths, to establish the feasibility of the concept are described. The field experiments indicate adequate phase changes, more than 1t-rad, are produced by intruders on foot and vehicle for burial depths in the 0.2 m to 1 m range in sand, clay and fine gravel soils. The simulations predict a range of 10 km with 35 m range resolution and 30 km with 90 m range resolution. This technology could in a cost-effective manner provide enhanced perimeter security.

• 조명전기설비학회논문지
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• 제22권1호
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• pp.73-78
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• 2008

대전류 측정용 편광 분석형 광섬유 CT를 개발하였다. 센서코일은 스펀 광섬유의 끝단에 FRM 반사경을 부착하여 개방형으로 구성하였으며, 전류측정 실험을 통한 출력신호의 선형화 오차는 ${\pm}2[%]$ 이내였다. 비틀림 광섬유와 flint glass 광섬유 센서코일을 동일한 조건에서 실험하여 비교 검토한 결과, 스펀 광섬유가 각각 50배, 2배 큰 전류측정 민감도를 가지고 있음을 확인할 수 있었다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.159-166
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• 2006

Although the strain distribution along the length of a beam in buildings or infrastructures is non-uniform, most fiber optic sensors are point sensors that can measure the strain only at a local point of a beam. Long gage fiber optic sensors that measure integrated strain over a relatively long length can consider strain variation. This type of sensor was found to be efficient and useful for monitoring large-scale structures. On the other hand, the maximum strain or stress in a beam can not be measured with long gage optic sensors. However, for the assessment of the safety of multi-span steel beams subjected to various vertical loads, the maximum strain or stress measured during monitoring is required for comparison with the allowable stress of the beam calculated by a design code. Therefore, in this paper, mathematical models are presented for determination of the maximum values of strains in more three-span steel beams based on the average strains measured by long gage optic sensors.

• Nuclear Engineering and Technology
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• 제52권8호
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• pp.1689-1696
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• 2020

In this study, we developed a fiber-optic humidity sensor (FOHS) system for the monitoring and detection of coolant leakage in nuclear power plants. The FOHS system includes an FOHS, a spectrometer, a halogen white-light source, and a Y-coupler. The FOHS is composed of a humidity-sensing material, a metal tube, a multi-mode plastic optical fiber, and a subminiature version A (SMA) fiber-optic connector. The humidity-sensing material is synthesized from a mixture of polyvinylidene fluoride (PVDF) in dimethyl sulfoxide (DMSO) and hydroxyethyl cellulose (HEC) in distilled water. We measured the optical intensity of the light signals reflected from the FOHS placed inside the humidity chamber with relative humidity (RH) variation from 40 to 95%. We found that the optical intensity of the sensing probe increased linearly with the RH. The reversibility and reproducibility of the FOHS were also evaluated.

• 조명전기설비학회논문지
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• 제29권8호
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• pp.76-82
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• 2015

A hybrid fiber-optic sensor system which combines fiber Bragg grating sensors and a Michelson interferometer has been constructed and evaluated for condition monitoring of large scale wind turbines. In order to measure multiple stresses applied to wind turbines such as strain, temperature and vibration, the system uses single broadband light source. It addresses both types of sensors, which simplifies the optical setup and enhances the cost-effectiveness of condition monitoring system. An athermal-packaged FBG is used to supply quasi-coherent light, of which coherence length is about 3.28mm, for the Michelson interferometer demodulation. Experimental results demonstrated that the proposed fiber-optic sensor system was capable of measuring strain and temperature with measurement accuracy of 1pm. Also 500~2000Hz vibration signals were successfully analyzed by applying FFT signal processing to interference signals.

• 한국통신학회논문지
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• 제29권10A호
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• pp.1200-1204
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• 2004

가변 광 감쇄기에 사용한 굽힘에 민감한 특수 광섬유 (BSF: bending-sensitive fiber)를 이용하여 굽힘에 따라 물리적인 변화를 감지해 내는 광섬유 센서(FOS: fiber-optic sensor)를 제작하였다. BSF를 이용한 FOS의 제작 가능성을 알아보기 위해 BSF의 굽힘 손실을 3차원 유한차분 빔 전파기법을 이용하여 전산모의 하였고 전산모의 결과를 실제 제작된 BSF를 이용한 FOS의 실험 결과와 비교하였다. 특히 제작된 FOS는 센서 상층부에 가해진 압력이 0 MPa에서 0.005 MPa 로 변할 때 광 에너지는 -1 dB에서 -20 dB 까지 감쇄하였다. 반면에 단일모드 광섬유(SMF: single mode fiber)를 이용하여 동일한 구조로 제작된 FOS는 광 에너지의 변화를 보이지 않았다.

• 한국광학회:학술대회논문집
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• 한국광학회 1999년도 제16회 광학 및 양자전자 학술발표회Proceedings of 16th Optics and Quantum Electronics Conference, 1999
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• pp.226-227
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• 1999

In the fiber-optic gyroscope employing the erbium-doped fiber source, the source excess noise was subtracted through a signal processing to improve the gyroscope sensitivity . As the result, we obtained the improvement of 14 dB(electrical) at the proper frequency, which was measured from the noise floor spectrum . In addition the random walk coefficient in the gyro output was reduced by about factor of three.

• 대한소아치과학회지
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• 제48권1호
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• pp.105-114
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• 2021

이 연구의 목적은 광중합기의 조사단에 광섬유를 적용하였을 때, 조사단과 교정용 버튼의 베이스 사이의 거리와 광섬유 직경에 따른 교정용 버튼의 전단결합강도를 평가하는 것이다. 발치된 소구치 315개를 I, II, III군으로 나누어 광섬유를 사용하지 않거나 3.0, 5.0 mm 직경의 광섬유를 사용하였고 각 군을 A, B, C의 하위군으로 분리하여 5.0, 10.0, 15.0 mm 깊이로 조사단과의 거리를 설정하여 전단결합강도를 측정하였다. 거리 증가에 따라 I군의 전단결합강도가 유의하게 감소하였다. 광섬유 직경에 따른 전단결합강도를 평가했을 때 거리가 5.0 mm인 경우 군 간에 유의성이 관찰되지 않았고 10.0 mm인 경우 IB군에 비해 IIIB군에서 유의하게 높은 전단결합강도를 보였고 15.0 mm인 경우 IC군에 비해 IIC, IIIC군 모두 유의하게 높은 전단결합강도를 보였다. 고로 광중합기의 접근성이 떨어질 때, 광섬유 사용이 추천되며 직경이 큰 광섬유가 성공적인 버튼 부착에 도움이 될 것으로 사료된다.