• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.505-510
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• 2002

We have focused on the development of a fiber optic BOTDA (Brillouin Optical Time Domain Analysis) sensor system in order to measure temperature distributed on large structures. Also, we present a feasibility study of the fiber optic sensor to monitor the distributed temperature on a building construction. A fiber optic BOTDA sensor system, which has a capability of measuring the temperature distribution, attempted over several kilometers of long fiber paths. This simple fiber optic sensor system employs a laser diode and two electro-optic modulators. The optical fiber of the length of 1400 m was installed on the surfaces of the building. The change of the distributed temperature on the building construction was well measured by this fiber optic sensor. The temperature changed normally up to 4℃ through one day.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1843-1845
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• 1998

Gyroscope is a very important core sensor as a rotation sensor in inertial space, in inertial guidance and navigation system on aeronautics. Plane, vessel and so on for civilian and millitary applications. Research and development of fiber optic gyroscope began in 1976 and focused on improving the gyroscope's sensitivity to rotation. bias performance and reducing noise. We have developed a Interferometric Fiber Optic' Gyroscope using a integrated-optic-circuit (IOC), which is operating with closed-loop electronic circuit. This paper describes the scheme of optical part and electronic part and also test results of this fiber optic gyroscope using a integrated-optic-circuit (IOC). The performance have been achieved as long-term bias drift of $1.73^{\circ}/h$.

• 조명전기설비학회논문지
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• 제27권3호
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• pp.1-6
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• 2013

In this study, we propose a fiber-optic hydrogen sensor using a polarization-diversity loop configuration composed of a polarization beam splitter, two quarter-wave plates, and a polarization-maintaining fiber coated with palladium whose thickness is ~400nm. One transmission dip of the output interference spectrum of the proposed sensor, chosen as a sensor indicator, was observed to spectrally shift with the increase of the hydrogen concentration, and the sensing indicator showed a wavelength shift of ~2.48nm at a hydrogen concentration of 4%. Except for a hydrogen concentration of 4%, the response time of the proposed sensor was measured as less than 12.5s and did not show significant dependence on the hydrogen concentration. In particular, the proposed fiber hydrogen sensor is more durable and highly resistant to external stress applied on a transverse axis of an optical fiber, compared with other hydrogen sensors based on side-polished fibers or fiber gratings.

• 전자공학회논문지A
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• 제32A권9호
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• pp.128-134
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• 1995

A fiber-optic temperature sensor utilizing an optical absorption device (InP) was fabricated. The spectrum of transmitted light through an InP device was obtained at the three temperatures(249 K, 369 K). A stabilized LED(light emmiting diode) driver, photoreceiver, and signal proocessing electronics were designed. An intensity referencing technique was adopted in order to minimize the fluctuation of output signal due to external pertubation of the transmitting optical fiber. The optical absorption edge of the InP device moves to longer wavelength at a rate of 0.42 nm / K, and energy gap of InP is 1.35 eV at room temperature. From these results, it is concluded that the InP device has temperature dynamic range of 300 K with LED of center wavelength of 940nm and spectral width of 50nm. The designed fiber-optic temperature sensor system showed good linearity within the temperature range from -30$^{\circ}C$ to + 150$^{\circ}C$.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권1호
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• pp.15-19
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• 2004

In this paper, we present the fabrication and characteristic analysis of Sagnac interferometric optical fiber senior(OFS) system for detecting pulsed ultrasonic signal in underwater. The hollow cylindrical mandrel wound round by single mode optical fiber is used as sensing component. The ultrasonic signal source is simulated by the PZT actuator operated by an function generator. The distance dependency of the OFS's sensitivity was measured. The sensitivity has been shown to be inversely propotional to the square-root of distance between ultrasonic source and sensing component. It has also been shown that the OFS could detect the signals less affected by ultrasonic path comparing to conventional acousto-electric sensor. and accurate location of ultrasonic signal could be carried out using two OFSs.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.62-66
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• 2002

The preliminary results on the application of optical fiber sensor(OFS) for locations of ultrasonic signals in underwater are presented and analyzed. The OFS utilizing the principle of Sagnac interferometry was designed and the hollowed cylindrical mandrel wound by single mode optical fiber was used as sensing component. The ultrasonic signal source was simulated by the PZT actuator operated with function generator. It has been shown that the OFS could detect the signals less affected by ultrasonic path comparing to conventional acousto-electric sensor and accurate location of ultrasonic signal could be carried out using two OFSs.

• 한국정보통신학회논문지
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• 제12권5호
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• pp.956-962
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• 2008

바닷속과 같은 수중에서 1개의 광섬유에 다량의 배열형 광센서를 접속하여 광범위한 영역에서의 원격 측정도 가능한 광 CDMA 기반 광섬유 센서를 이용한 음파탐지 시스템을 제안한다. 그리고 제안 시스템에서 잡음특성을 이론적으로 분석하고 컴퓨터 시뮬레이션에 의하여 그 결과를 분석한다. 광 CDMA 기반 광섬유 센서를 이용한 음파탐지 시스템에서 센서의 측정 시간을 증가시키면 종래의 WDMA 방식을 적용할 경우 보다 많은 광센서가 접속 가능한 것을 알 수 있다.

• 한국공작기계학회논문집
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• 제14권6호
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• pp.37-44
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• 2005

This paper presents fabrication techniques of the optical fiber position sensor (or spindle state monitoring. These include selection of components such as optical fibers, a laser-diode, a photo-diode, and op-amp IC of the signal process circuit. We also describe electric runout problem. The fabricated sensor has a linearity of $1.7\%$ FSO in the air gap range $0.1\~0.6mm$, a resolution of $0.37{\mu}m$ and a bandwidth of 6.3kHz. Finally, we have successfully operated a magnetic bearing spindle system using the sensors.

• 대한의용생체공학회:의공학회지
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• 제30권6호
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• pp.489-494
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• 2009

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.

• 조명전기설비학회논문지
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• 제27권8호
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• pp.75-82
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• 2013

We propose a fiber grating sensor system for condition monitoring of large scale wind turbine blades. For the feasibility test of the proposed sensor system, a down-scaled wind turbine has been constructed and experimented. Fiber grating sensors were attached on a blade surface for distributed strain and temperature measurements. An optical rotary joint was used to transmit optical signals between the FBG sensor array and the signal processing unit. Instead of broadband light source, we used a wavelength-swept fiber laser to obtain high output power density. A spectrometer demodulation is used to alleviate the nonlinear wavelength tuning problem of the laser source. With the proposed sensor system we could measure dynamic strain and temperature profiles at multi-positions of rotating wind turbine blades.