• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
• /
• pp.1746-1749
• /
• 1997

A distributed optical fiber temperature sensor can continually monitor the measurand at every point along of its fiber length. It is based on OTDR technics which used extreamlly weak backward scattered light called Raman scattering. When the Pulsed high intensity laser light injected into the optical fiber there are several kind of backscattered light such as Rayleigh, Stokes, and anti-Stokes, etc. caused by impurities molecular vibrations. The temperature distribution is derived form the intensity ratio Raman scatted light-Stokes versus anti-Stokes-and the time function between light injection and signal detection. It is shown that the priniciple of distributed sensing, the system desing, and the result of experiments.

• 한국광학회지
• /
• 제21권6호
• /
• pp.230-234
• /
• 2010

큰 복굴절 값을 갖는 광자결정광섬유는 실리카 단일 물질로 구성되어 온도 민감성이 매우 낮다. 이를 이용하여 온도변화에 영향을 받지 않는 스트레인 및 구부림 센서를 구현하였다. 이때, 스트레인 변화에 따른 민감도는 $1.41\;pm/{\mu}{\varepsilon}$ 이고, 구부림에 대한 민감도는 타원코어 장축 방향과 단축 방향으로의 구부렸을 때 각각 $0.93\;nm/m^{-1}$, $-1.6\;nm/m^{-1}$ 로 차이가 있었다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
• /
• pp.597-600
• /
• 1996

This study has compared the two types of systems which measure the temperature of coal powder in feeder lines of boiler and analyzed operating data. We used RTD(Resistance Temperature Detector) and optic sensors to measure the temperature. From the characteristic comparison of data, field test and system operation, we confirm that the latter is more efficient than the former.

• 한국전기전자재료학회논문지
• /
• 제31권3호
• /
• 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.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 추계학술대회 논문집
• /
• pp.471-474
• /
• 2002

A fuel tank contains water at the bottom under the fuel. The water comes from humidity by temperature change of inside and outside of tank. So it is necessary to measure both level to check precise amount of oil. But measuring instrument for level of water and fuel is not available yet. Since the fuel is inflammable, the sensor system must not include any electric circuits in the fuel tank. Optical cable sensor can satisfy this non-explosive condition. The displacement of a float changing by water level makes bending curvature of optical cable different. As the float rise up, the optical cable is bent more and the light signal in the cable decreases. The reduction of light signal is detected and it is converted into the change of water level. The output signal from a photo diode shows the proportional relation of water level. The increase of sensor voltage as a unit of ㎷ follows the level position of the float that is located between water and gasoline in the tank.

• 센서학회지
• /
• 제23권2호
• /
• pp.110-113
• /
• 2014

In this paper, we propose and demonstrate a Fabry-Perot interferometer (FPI) optical fiber tip sensor fabricated by a blade-sawing technique using a fiber optic patch cord for high-resolution temperature measurement. The sensor head consists of a short air FP cavity near the tip of a single-mode fiber patch cord tip. The temperature which we can measure is determined through a phase variation of the interference fringes in the reflective spectrum of the sensor. The fiber optic FPI sensor in this work can monitor the environmental temperature very accurately from 40 to $120^{\circ}C$. As a result, the temperature sensitivity is obtained as $38.2pm/^{\circ}C$.

• 한국가스학회:학술대회논문집
• /
• 한국가스학회 2006년도 추계학술발표회 논문집
• /
• pp.123-128
• /
• 2006

This paper describes NDIR $CO_2$ gas sensor that shows the characteristics of temperature compensation. It consists of novel optical cavity that has two elliptical mirrors and a thermopile detector that includes ASIC chip in the same metal package for the amplification of detector output voltage and temperature sensor. The newly developed sensor modules shows high accuracy (less than +/-40 ppm) throughout the measuring concentration of $CO_2$ gas from 0 ppm to 2,000 ppm. After implementing the calculation methods of gas concentration, which is based upon the experimental results, the sensor module shows high accuracy less than +/- 5 ppm error throughout the measuring temperature range $(15^{\circ}C\;to\; 35^{\circ}C)$ and gas concentrations.

• 한국광학회지
• /
• 제17권3호
• /
• pp.223-230
• /
• 2006

직접 광주파수 변조된 레이저 다이오드를 광원으로 이용하여 공간 선택적 브릴루앙 산란 방식으로 분포형 광섬유 센서를 구성하여 실험하였다. 광주파수가 정현파로 변조된 펌프와 프로브 빛이 광섬유 내로 서로 반대 방향으로 진행하며 중첩되도록 함으로써 광섬유 내 특정 지점에서만 유도 브릴루앙 산란이 발생하도록 하였으며, 변조 주파수를 변화시켜 브릴루앙 이득 피크의 위치를 조절할 수 있었다. 브릴루앙 천이 주파수가 서로 다른 광섬유를 접속한 경우와 광섬유 길이를 따라 온도 분포가 존재하는 경우에 대해 각각 브릴루앙 천이 주파수의 분포를 측정하였다. 브릴루앙 천이 주파수의 온도 변화율은 $1.33MHz/^{\circ}C$로 측정되었다.

• 한국소음진동공학회논문집
• /
• 제17권12호
• /
• pp.1195-1200
• /
• 2007

Torque of a rotating shaft has been mostly measured by strain gages combined with either a slip ring or telemetry. However, these methods have severe inherent problems like low S/N ratio, high cost, limited number of channels and difficult installation. In this paper, a new method using FBG(fiber bragg grating) sensors and a rotary optical coupler for online non-contact torque monitoring is suggested. FBG sensor can measure both strain and temperature, and has much batter characteristics than those of a strain gage. A rotary optical coupler is a optical connecting device between a rotating shaft and stationary side without any physical contact. It has been devised for transmitting light between a rotating optical fiber and a stationary optical fiber. The proposed method uses this rotary optical coupler to connect FBG sensors on the rotating shaft to instruments at stationary side. And a reference FBG sensor is also applied to compensate the insertion loss change of the rotary optical coupler due to rotation. Three FBG sensors have been fabricated in a single optical fiber. Two FBG sensors are attached on the shaft surface to measure torque and one sensor is installed at the shaft center to compensate the insertion loss change. The torque of a rotating shaft has been successfully measured by the suggested method proving its superior performance potential.

• 센서학회지
• /
• 제15권4호
• /
• pp.297-301
• /
• 2006

We have fabricated a multi-mode nonlinear plastic optical fiber (POF) using organic nonlinear optical materials and demonstrated the propagation of light. The refractive indices of core and cladding are 1.5240 and 1.5172. We made a POF preform by rod-in tube method. The core diameter of the fabricated POF is about $30{\mu}m$. We evaluated the temperature characteristics of POF. The sensitivity is $0.345{\;}mW/^{\circ}C$ and the linearity of sensor was good.