• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.334-337
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• 2007

본 연구는 출력특성의 안정성과 정밀성이 우수한 광전류센서의 개발을 위하여 센싱부의 온도변화에 따른 출력신호를 검토하고, 온도변화에 따른 출력특성이 안정된 센싱부를 적용하여 출력특성을 연구하였다. 기존 광전류센서에서 중요시스템인 센싱부의 광섬유의 온도특성과 Verdet 상수의 온도의존도에 따라 출력신호가 불안정하다. 이러한 광전류센서의 온도변화에 따른 오차를 개선하기 위해 센싱부에 대한 온도특성을 분석하고, 온도변화에 내구성이 뛰어난 소재를 적용함으로써 센싱부의 안정된 출력특성을 가지는 광전류센서를 개발하고자한다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.342-345
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• 2007

본 연구에서는 광섬유형(Fiber Optic Current Sensor) 광전류센서 구성 시 발생하는 선형복굴절(Linear Birefringence)의 보상에 용이한 수직원형틀(Orthogonal Loop Type) 센서헤드(Sensor Heads)를 개선하여 1 Cross 수직원형틀(l Cross Orthogonal Loop Type)을 제시하였다. 그리고 기존의 페루프형 원형틀 (Closed Loop Type), 수직원형틀 그리고 1 Cross 수직원형틀의 편광상태를 비교하였다. 그 결과 편광상태 측정 시 페루프 원형틀을 수직원형틀로 교체할 경우 15.3%, 1 Cross 수직원형틀로 교체할 경우 33.8%의 선형복굴절 감소 효과가 나타났다. 이에 1 Cross 수직원형틀을 광전류센서에 적용할 경우 안정된 편광특성으로 고신뢰성 광전류센서 개발 가능성을 높게 할 것이다.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.8
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• pp.841-846
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• 2014

FBG sensors are mainly used to measure deformation of structures such as tunnels, bridges and ships. In this paper, an interrogator of FBG sensors is developed and implemented to measure the status of structures. A developed interrogator includes CAN wired and Zigbee wireless communication for remote monitoring. Strain of structure is measured using shift of wavelength of reflected light from FBG sensor. A digital signal controller is used to process signals of a FBG sensor and transmit data for remote monitoring. As a result of experiment, developed interrogator is effective to measure deformation of structures.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.7
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• pp.1607-1612
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• 1997

A new method of stabilizing a Sagnac optical fiber current sensor is presented. This method is characterized by creating aproper amount of circular birefringence the fibersagnac, whose correaponding value of rotation angle is (m+1/2)$\pi$-$2\Psi$, removes the effect of linear birefringence and leads to achieve good stability. Using the technique the stability of the current sensor was improved more than 10 times to within ${\pm}2.3{%}$ at 300Arms.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.1
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• pp.89-98
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• 2002

Optical current sensor and optical voltage sensor modules were designed and fabricated to improve measurement error and insulation in automatic power distributor By using Faraday effect, optical current sensor with an $\alpha$-iron core was designed and fabricated to minimize current induction of the other phase and was optimized to maintain linearity. Optical voltage sensor was fabricated owing to the pockets effect and adopted spatial electric field type because of small room in an automatic power distributor. To connect a distributor with an external terminal for signal processing, optical multi connector was designed, fabricated and tested for coupling loss and gas leakage. The linearity of optical current sensor for applied current maintains variation of smaller than 2.5% for applied current range from 20A to 700A. The linearity of optical voltage sensor was smaller than 1% for appling voltage from 6.6kV to 19.8kV. Since the measured characteristics are good, these devices can be considered as being applicable in practice.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.1
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• pp.111-116
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• 2006

In this paper, the image sensor using the a-Si:H TFT is proposed. The optimum amorphous silicon thin film is deposited using plasma enhanced chemical vapor deposition (PECVD). TFT and photodiode both with the thin film are fabricated and form image sensor. The photodiode shows that Idark is $10^{-12}A$, Iphoto is $10^{-9}A$ and Iphoto/Idark is $10^3$, respectively. In the case of a-Si:H TFT, it indicates that Ion/Ioff is $10^6$, the drain current is a few ${\mu}A$ and Vth is $2\~4$ volts. For the analysis on the fabricated image sensor, the reverse bias of -5 voltage in ITO of photodiode and $70{\mu}sec$ pulse in the gate of TFT are applied. The image sensor with good property was conformed through the measured photo/dark current.

• Korean Journal of Optics and Photonics
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• v.30 no.6
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• pp.249-254
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• 2019

An optical current sensor device that measures electric current by the principle of the Faraday effect was designed and fabricated. The polarization-rotated reflection interferometer and the quadrature phase interferometer were introduced so as to improve the operational stability. Complex structures containing diverse optical components were integrated in a polymeric optical integrated circuit and manufactured in a small size. This structure allows sensing operation without extra bias feedback control, and reduces the phase change due to environmental temperature changes and vibration. However, the Verdet constant, which determines the Faraday effect, still exhibits an inherent temperature dependence. In this work, we tried to eliminate the residual temperature dependence of the optical current sensor based on polarization-rotated reflection interferometry. By varying the length of the fiber-optic wave plate, which is one of the optical components of the interferometer, we could compensate for the temperature dependence of the Verdet constant. The proposed optical current sensor exhibited measurement errors maintained within 0.2% over a temperature range, from 25℃ to 85℃.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.493-496
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• 2000

This study is about the design and fabrication of optical voltage sensor modules improved in the insulation reliability, where we adopted the space-division voltage system using the auxiliary electrodes to apply the uniform electric fields to the BSO, the device of which the polarization state varies with the variation of refractive index in the electric fields. We measured the output of fiber-Optic Voltage Sensors with the temperature changes in the thermostatic oven. And we measured the output of Fiber-Optic Voltage Sensors after setting its up in the disttibuion automated switch being apply 60Hz alternating voltage from 6.6kV to 17.BkV. In result, measured error characteristic is good, so we can judge it is applicable to the practical case

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.217-225
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• 2003

In this paper, in order to investigate the near field distribution characteristic of the Loop Antenna we simulated and measured the near field of a Loop Antenna using optical electric-field sensor in a large Chamber(8.5 m x 7 m x 7 m). The simulation methods were used MoM for frequency domain and FDTD for time domain. From the analysis results, it can be seen that the simulation and measurement results are very aggregated, and the optical electric-field sensor is a certificate of validity. In frequency domain, in case of the optical sensor with vertical polarization is located above the near vertical line of the Loop Antenna the signal strength level is more 15 ㏈ than with horizontal polarization. But in case of the optical sensor located above horizontal line of the Loop Antenna, signal strength level is not different. And, in the time domain, although input signal is positive, in the case of the optical sensor with vertical polarization is located above horizontal line of the Loop Antenna, it can be seen that the received pulse shape is negative.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.215-220
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• 2005

In order to apply to land mine detection effectively, GPR using an optical electric field sensor as a receiver has been developed. The optical electric field sensor is very small and uses optical fiber instead of metallic coaxial cable. With the combination of these advantages and the bistatic radar system, it can be possible for an operator to measure quite flexible and safely. The sensor has been tested in stepped frequency radar system with frequency which consists of a vector network analyzer, a fixed double ridged horn antenna as transmitter. For considering effectiveness in real field, we applied impulse radar system, which consist of a digital oscilloscope and a impulse generator to produce the impulse. Detection of a PMN2 mine model was carried out by the impulse radar system at a sand pit. The PMN2 were detected clearly with sufficiently high resolution, the target contrast was almost the same while the scanning time decreased down to 1/100.