• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1823-1825
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• 2007

Based on Faraday effect, the variation of current flowing through the conductor can be encoded as that of azimuth angle of light polarization propagating through the fiber coil wound onto the conductor. The amount of current can be obtained by measuring the variation of the light intensity transformed from that of the azimuth angle through a polarization analyzer. In this paper we propose a fiber-optic current sensor system that employs a fiber polarization analyzer as a sensor interrogation device. The fiber polarization analyzer was prepared by inscribing a long-period fiber grating on a high birefringent fiber. At the fixed wavelength of 1522.5 nm, the fabricated fiber device has the polarization extinction ratio of more than 25 dB. The measurement of large current up to 600 Arms was accomplished based on a simple fiber interrogation device and the measurement output of the sensor system showed a good linearity.

• Journal of Sensor Science and Technology
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• v.6 no.3
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• pp.172-179
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• 1997

This paper describes a multiplexed-multivariate fiber-optic interferometric sensor system with remote sensing capability. Signal processor of the implemented sensor system is designed as a digital fringe counter that is well adapted to the signal processing of the remote fiber-optic Fabry-Perot interferometric sensor array. By summing up the reported optical data of the optical fiber, a guideline for choosing the optical effect suitable for a specific measurand is presented. As an example, a pressure sensing device that utilizes the strain-optic effect of the optical fiber by attaching it onto a stainless steel diaphragm of which diameter is 4.3 cm, is built and attached to the sensor system. The changes in optical phase difference of the fiber-optic Fabry-Perot interferometric press ure sensor while filling a water tank 2 meters high, was counted by the half-fringe counting signal processor. Test results showed that the measurement error is less than ${\pm}3.6\;cm$ over the measured range of 2 meters.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1100-1109
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• 2006

In this study, two different technologies which can measure temperature simultaneously at many points are introduced. One is to use a thermal sensor cable that is comprised of addressable thermal sensors connected in parallel within a single cable. The other is to use an optic fiber with Distributed Temperature Sensing (DTS) system. The difference between two technologies can be summarized as follows. A thermal sensor cable has a concept of 'point sensing' that can measure temperature at accurate position of a thermal sensor. So the accuracy and resolution of temperature measurement are up to the ability of the thermal sensor. Whereas optic fiber sensor has a concept of 'distributed sensing' because temperature is measured by ratio of Stokes and anti-Stokes component intensities of Raman backscatter that is generated when laser pulse travels along an optic fiber. It's resolution is determined by measuring distance, measuring time and spatial resolution. The purpose of this study is that application targets of two temperature measurement techniques are checked in technical and economical phases by examining the strength and weakness of them. Considering the functions and characteristics of two techniques, the thermal sensor cable will be suitable to apply to the assessment of groundwater flow, geothermal distribution and grouting efficiency within 300m distance. It is expected that the optic fiber sensor can be widely utilized at various fields (for example: pipe line inspection, tunnel fire detection, power line monitoring etc.) which need an information of temperature distribution over relatively long distance.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.2
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• pp.219-228
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• 2022

One of the most pressing and demanding issues today in the conditions of widespread transformation and digitalization of spheres of human activity is information security and ensuring the integrity of data. The main research and development in the field of information security is aimed at improving efficiency and rationalization. One of the main means of data transmission and operation of information complexes are fiber-optic systems. To date, there have been incidents of illegal intrusion and theft of information, passing through this type of communication. Thus, today there is a problem associated with insufficient information security in fiber-optic data transmission systems. One of the most effective tools to counter acts of illegal interference in systems are artificial intelligence and cryptographic algorithms of information protection. It is the symbiosis of these two tools that can qualitatively improve the level of information security in fiber-optic data transmission systems. Thus, the authors of this article pursue the goal associated with the description of an innovative system for protecting information from violations in fiber-optic data transmission systems based on the integration of intelligent cryptographic algorithms.

• Korean Journal of Optics and Photonics
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• v.21 no.1
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• pp.12-15
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• 2010

In this paper, we have proposed and demonstrated a simple fiber-optic temperature sensor based on the bending loss of a TEC(thermally expended core) fiber attached to a bi-metal. The deformation of the bi-metal caused by the change in its temperature induces the bending loss of the TEC fiber. The experimental result shows that the temperature sensitivity and operation temperature range of the device are controllable through the adjustment of the structure of the expanded core fiber. The fabrication procedure of the device is described in detail.

• Korean Journal of Optics and Photonics
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• v.14 no.2
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• pp.155-160
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• 2003

We have constructed and characterized a depolarized fiber-optic gyroscope that uses a length of single-mode fiber as a sensing loop fiber. We have also calculated the noise characteristics of the gyroscope and have found an optimum phase modulation depth that gives the highest signal-to-noise ratio in the gyroscope. The random walk coefficient as small as 0.7$\times$10$^{-3}$ deg/√hr was obtained at the modulation depth of around 2.4 rad. The random walk coefficients measured at various modulation depths were found to be in reasonable agreement with the calculation.

• 전기의세계
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• v.33 no.10
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• pp.599-606
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• 1984

Fiber-optic gyroscope는 시스템의 감도가 광섬유 turn수에 비례하여 증가될 수 있으며 측정 범위가 넓고 (-$10^{8}$), low drift, 선형적응답등의 기술적 장점뿐만 아니라, 시스템의 직접화에 의한 소형화 및 안정화가 기대되어 저렴한 가격에 대량생산이 가능하여 앞으로 기존의 모든 inertial 시스템을 대치할 것으로 전망되어 이에 대한 연구개발이 주목되고 있다.

• Proceedings of the SAREK Conference
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• 2003.07a
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• pp.182-182
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• 2003

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.167-168
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• 2006

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.314.1-314.1
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• 2008