• Proceedings of the Optical Society of Korea Conference
• /
• 2009.10a
• /
• pp.365-366
• /
• 2009

• Proceedings of the KIEE Conference
• /
• 1998.07e
• /
• pp.1837-1839
• /
• 1998

This paper proposes the strain-insensitive temperature sensing in quasi-distributed sensor system using different thermal expension coefficient materials. This system has the high sensitivity and hasn't the necessity of reference signal. We can monitor the condition of the power cable with this system.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.28A no.9
• /
• pp.721-728
• /
• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.36 no.6
• /
• pp.594-597
• /
• 2023

We have proposed and demonstrated a fiber optic RH (relative humidity) sensor based on fiber Bragg grating covered with a polyimide film. As the polyimide film absolves the moisture in the air, its volume expands. As a result, the grating period of the FBG (fiber Bragg grating) covered with a polyimide film becomes wide and the Bragg wavelength is shifted. The sensor is implemented by fixing a 30 ㎛ thickness polyimide film on the surface of an optical fiber grating using an adhesive, and the characteristics of the device according to humidity are analyzed. The fabricated FBG RH sensor showed a high sensitivity of 0.0186 nm/RH% and a wide measurement range from 30% to 90%. The influence of environmental temperature on the characteristics of the RH sensor was also measured and analyzed. The feasibility of commercialization is presented.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.31 no.3
• /
• pp.160-164
• /
• 2018

We have proposed a hydrogen detection sensor based on a Pd (palladium)-coated, single-mode, optical fiber. The experimental results demonstrated that the sensor could detect hydrogen in air as well as in insulation oil. The influence of Pd film thickness and environmental temperature on response time and sensitivity was analyzed. The reflected optical power at the optical-fiber/Pd interface decreased as the concentration of hydrogen increased, in both air and the insulation oil. The sensor showed 0.75 dB of optical power variation when the concentration of dissolved hydrogen was saturated in the insulation oil.

• Journal of Sensor Science and Technology
• /
• v.4 no.2
• /
• pp.22-28
• /
• 1995

A Michelson interferometric AC current sensor has been fabricated by using a single mode optical fiber and a cylindrical PZT tube of which a radial dimension varies with applied voltage. The signal processing scheme used in this work, measures the magnitude of AC current regardless of the frequency of the current. An AC current is measured by counting the number of interference fringe during half cycle of the AC current. The number of interference fringes varies linearly with the magnitude of the current and the error range is within 5% at the temperature range from $-20^{\circ}C$ to $80^{\circ}C$.

• Journal of the Korean GEO-environmental Society
• /
• v.16 no.6
• /
• pp.39-43
• /
• 2015

This study extends the Distributed Temperature Sensing (DTS) application to delineate the saturated zones in shallow sediment and evaluate the groundwater flow in both downward and upward directions. Dry, partially and fully saturated zones and water level in the subsurface can be recognized from this study. High resolution seepage velocity in vertical direction was estimated from the temperature data in the fully saturated zone. By a single profile, water level can be detected and seepage velocity in saturated zone can be estimated. Furthermore, thermal gradient analysis serves as a new technique to verify unsaturated and saturated zones in the subsurface. The vertical seepage velocity distribution in the recognized saturated zone is then analyzed with improvement of Bredehoeft and Papaopulos' model. This new approach provides promising potential in real-time monitoring of groundwater movement.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.17 no.2
• /
• pp.142-152
• /
• 1992

This paper presentes a new method to measure high electric field (or high voltage) by using crystalline SiO2 which has very high half wave voltage. There are many difficulties in measuring high electric field using other crystals which have generally low half wave voltage.By applying Stokes parameter and Mueller matrix. We derive optical modulation equation in the sensor which is composed of a polarizer, and Mueller matrix, we derive optical modulation equation in the sensor which is composed of a polarizer, a Pokels material, and an analyzer, We theoretically analyzed electro-optic effect, and calculated the phase retardation and half wave volt age of the birefringent material. The designed optical valtage sensor has very excellent linearity up to 20KV without divided volt-age. The maximum error was measured within 3%. Before annealing of Sio2 crystal, the maximum variation of the output voltage is 7.5% with varying temperature from \ulcorner20˚c to 60˚c. But, after annealing of SiO2 crystal, the output voltage variation is improved within 1%error.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.36 no.3
• /
• pp.211-216
• /
• 2016

In several industrial fields, epoxy resin is widely used as an adhesive for co-curing and manufacturing various structures. Controlling the manufacturing process is required for ensuring robust bonding performance and the stability of the structures. A fiber optic sensor is suitable for the cure monitoring of epoxy resin owing to the thready shape of the sensor. In this paper, a fiber Bragg grating (FBG) sensor was applied for the cure monitoring of epoxy resin. Based on the experimental results, it was demonstrated that the FBG sensor can monitor the status of epoxy resin curing by measuring the strain caused by volume shrinkage and considering the compensation of temperature. In addition, two types of epoxy resin were used for the cure-monitoring; moreover, when compared to each other, it was found that the two types of epoxy had different cure-processes in terms of the change of strain during the curing. Therefore, the study proved that the FBG sensor is very profitable for the cure-monitoring of epoxy resin.

• Proceedings of the KIEE Conference
• /
• 2009.04a
• /
• pp.219-221
• /
• 2009

본 논문에서는 전기설비의 전기적 접속부 또는 전기배선 등에서 발생하는 발열상태를 실시 간으로 모니터링하는 전력설비 진단시스템에 사용되고 있는 광온도센서에 대하여 열원에 따른 동작특성을 실험, 분석하였다. Heimann Sensor사의 광온도소자를 이용하여 광온도센서를 제작하여 실험에 사용하였으며, 열원으로는 Black Body와 Hot Plate를 사용하였으며 각각에서의 열원의 온도변화에 따른 광온도센서의 출력전압값을 측정, 비교 분석하였다. 실험결과, Black Body에 의한 온도 측정이 Hot Plate에서보다 더 정밀함을 확인할 수 있었다. 이러한 분석 결과는 향후, 전력설비 진단시스템의 현장 적용에 있어 광온도센서의 출력값과 실측값의 매칭을 위한 기본 자료가 될것으로 기대된다.