• Current Optics and Photonics
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• 제6권3호
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• pp.297-303
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• 2022

Multiple fiber Bragg gratings (FBGs) have been proposed and demonstrated for gas-flow measurements in a flow channel, using the temperature-difference method. This sensor consists of two FBG temperature sensors and two coil heaters. Coil heaters are used to heat the FBGs. The flow rate of the gas can be obtained by monitoring the difference in the Bragg-wavelength shifts of the two FBGs, which has features that exclude the effect of temperature fluctuations. In this study, experiments are conducted to measure the wavelength shift based on the flow rate, and to evaluate the gas-flow rate in a gas tube. Experimental results show that the sensor has a linear characteristic over a flow-rate range from 0 to 25 ℓ/min. The measured sensitivity of the sensor is 3.2 pm/(ℓ/min) at a coil current of 120 mA.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.557-560
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• 1989

For the purpose of increasing supply reliabiity in power line, high reliable voltage and current sensors must be needed. This paper describes the principle and result of the only optical voltage sensor based on BSO pockels cell.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.964-967
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• 2009

A new hybrid-type touch screen panel (TSP) has been developed based on a-Si:H TFT which can detect the change of both $C_{LC}$ and photo-current. This TSP can detect the difference of $C_{LC}$ between touch and no-touch states in unfavorable conditions such as dark ambient light and shadows. The hybrid TSP sensor consists of a detection area which includes one TFT for photo sensing and two TFTs for amplification. Compared to a single internal capacitive TSP or an optical sensing TSP, this new proposed hybrid-type TSP enables larger sensing margin due to embedding of both optical and capacitive sensors.

• 전자공학회논문지A
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• 제28A권9호
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• pp.721-728
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• 1991

In this paper, a magneto-optic modulator has been designed by using single crystal BSO and polycrystal ZnSe as Faraday cells. And practical core-type optical current sensors using pure iron and permalloy have been prepared and experimented. In order to obtain efficient magnetic field detection, LED(NEC OD08358, 0.87 $\mu$m) was used as optical source, PIN-PD(OD-8454)as optical receiver and multi-mode optical fiber (100/140$\mu$m) as transmission line. The characteristics matrix of the optical element was calculated by Stokes parameter, and optic modulation characteristics equations were derived by Muller matrix. Electromagnetic analysis program (FLUX 2D, micro VAX 3600) by finite element method was used to find the magnetic flux density around the core. The measuring error of the output voltage to input current has been masured below 5% in the range of 50A to 1000A. As the temperature was changed from -20$^{\circ}C$ to 60$^{\circ}C$, the maximum measurement error of the optical output has been found to be 0.5% at 60$^{\circ}C$. These experimental results show good temperature and linearity characteristics. The SNR of the overall system was 47dB in case of 600A (250.2 Oe) conductor current and the system has good noise immunity.

• Current Optics and Photonics
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• 제8권5호
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• pp.508-514
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• 2024

This paper presents a deep learning-based weight sensor, using optical speckle patterns of multimode fiber, designed for real-time intrusion detection. The weight sensor has been trained to identify 11 distinct speckle patterns, ranging in weight from 0.0 kg to 2.0 kg, with an interval of 200 g between each pattern. The estimation for untrained weights is based on the generalization capability of deep learning. This results in an average weight error of 243.8 g. Although this margin of error precludes accurate weight measurement, the system's ability to detect abrupt weight changes makes it a suitable choice for intrusion detection applications. The weight sensor is integrated with the Google Teachable Machine, and real-time intrusion notifications are facilitated by the ThingSpeak^TM cloud platform, an open-source Internet of Things (IoT) application developed by MathWorks.

• Current Optics and Photonics
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• 제7권5호
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• pp.504-510
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• 2023

An optical fiber dislocation fusion humidity sensor coated with graphene quantum dots is investigated. A Mach-Zehnder interferometer is fabricated with three dislocated single-mode fibers with graphene quantum dots coating humidity-sensitive materials. Humidity response experiments showed a good linear response and high sensitivity with easy fabrication and low-cost materials. From 22% to 98% RH, the humidity response sensitivity of the sensor is 0.24 dB/% RH, with 0.9825 linearity. To investigate the cross-response of humidity and temperature, temperature response experiments are conducted. From 30 ℃ to 70 ℃, the results showed 0.02 dB/℃ sensitivity and 0.9824 linearity. The humidity response experimental curve is compared with the temperature experimental curve. The big difference between humidity sensitivity and temperature sensitivity is very helpful to solve the cross-response of humidity and temperature. The influence of temperature fluctuations in humidity measurements is not obvious.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 춘계종합학술대회
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• pp.271-274
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• 2002

본 논문에서는 광센서용 광원에 적합한 1.55$\mu\textrm{m}$ 파장대의 InGaAsP/InP 반도체레이저를 제작하였다. 레이징을 억제시켜주기 위해서 bending type의 소자를 설계 및 제작하였으며, 제작된 소자의 출력은 펄스 구동전류 100㎃에서 1.6㎽이고, 스펙트럼 폭은 40nm의 값을 가졌다. 그리고, 제작된 광원을 적용하였을 때 광섬유 자이로스코프에 파이버 종단에서의 출력은 $25^{\circ}C$, 직류 100㎃에서 540㎻였고, 스펙트럼 폭은 53nm였다. 그리고, 불규칙잡음 계수는 2.5$\times$10­$^3$deg/√hr였고, 자이로 출력 drift도 잡음수준으로 조사되었다. 따라서, 본 연구에서 제작한 광원을 광섬유 자이로 스코프에 사용 가능함을 확인하였다.

• 한국통신학회논문지
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• 제22권7호
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• pp.1607-1612
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• 1997

본 논문에서는 Sagnac 광섬유 광전류센서를 구성하여 전류센서의 출력을 항상 최대로 유지하여 안정성을 높일수 있는 새로운 방법을 제안한다. 제안한는 방법은 Sagnac 광전류센서의 감지부에 부착된 광섬유를 비틀림함으로써 원형복굴절에 의한 회전각을 (m+1/2)$\pi$-$2\Psi$ 만큼 야기시켜 선형복굴절의 영향을 없애줄 수 있으며 따라서 광전류센서의 출력을 안정화 시킬 수 있다. AC 전류신호 300Arms에서 실험해본 결과 안정화 방법을 적용하지 않았을때는 광전류센서의 출력변화율은 ${\pm}27{%}$였지만 안정화 방법을 적용했을때는 출력변화율이 ${\pm}2.3{%}$로 10배 이상 안정화 되는 것을 알 수 있었다.

• 한국광학회지
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• 제14권4호
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• pp.399-405
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• 2003

FD10 유리를 이용한 클램프형 광전류 센서를 제작하였다. 대칭형 구조로 이루어진 2조각의 FD10유리를 이용하여 제작하였으며, 센서헤드 내부에서 반사시에 위상차가 발생하는 것을 방지하기 위해 정확히 임계각으로 광이 진행하도록 구조를 설계하였다. 제작한 광-전류 변류기 헤드를 이용하여, 0-1,000 AT 까지의 전류를 측정하고, 빛의 입사각에 따른 광의 손실, 입사광의 편광회전에 따른 광출력변화, 온도에 따른 출력의 변화 및 장시간 전류 측정 등에 대한 실험결과를 제시하고 이에 대한 분석을 통해 제작된 광전류 변류기 헤드의 전류계로서의 가능성을 입증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기물성,응용부문
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• pp.38-40
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• 2001

Fiber-optic current sensor was developed using the Faraday effect to measure the electrical current on high-voltage lines. A twisted single-mode optical fiber was used as a sensor coil to suppress birefringence effect, enhancing performance against environmental perturbations. In this paper, we report the basic design considerations and the preliminary experimental results carried out in the 1000 A input current range.