• 제목/요약/키워드: temperature sensors

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Fault Diagnosis and Recovery of a Thermal Error Compensation System in a CNC Machine Tool (CNC 공작기계에서 열변형 오차 보정 시스템의 고장진단 및 복구)

  • 황석현;이진현;양승한
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.4
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    • pp.135-141
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    • 2000
  • The major role of temperature sensors in thermal error compensation system of machine tools is improving machining accuracy by supplying reliable temperature data on the machine structure. This paper presents a new method for fault diagnosis of temperature sensors and recovery of faulted data to establish the reliability of thermal error compensation system. The detection of fault and its location is based on the correlation coefficients among temperature data from the sensors. The multiple linear regression model which is prepared using complete normal data is also used fur the recovery of faulted data. The effectiveness of this method was tested by comparing the computer simulation results and measured data in a CNC machining center.

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Local heat transfer measurement inside microchannel (마이크로채널에서의 국소 열전달 측정)

  • Cho, Dae-Gwan;Lee, Joon-Sik
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.1902-1907
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    • 2008
  • The current work presents a design and fabrication technique for a microchannel system to measure the local temperature distribution inside microchannel. This micro channel system fabricated by MEMS technique is integrated with a heater and an array of temperature sensors so that detailed heat transfer phenomena inside micro-scale channel can be studied. Materials widely used in semiconductor process were selected to fabricate a heater and temperature sensors on a silicon wafer. On these heater and sensors a channel wall was fabricated with SU-8. The friction constant and the local Nusselt number distribution measured for the deionized water flow in the microchannel is presented.

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Design, Simulation, and Optimization of a Meander Micro Hotplate for Gas Sensors

  • Souhir, Bedoui;Sami, Gomri;Hekmet, Charfeddine Samet;Abdennaceur, Kachouri
    • Transactions on Electrical and Electronic Materials
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    • v.17 no.4
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    • pp.189-195
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    • 2016
  • Micro Hotplate (MHP) is the key component in micro-sensors, particularly gas sensors. Indeed, in metal oxide gas sensors MOX, micro-heater is used as a hotplate in order to control the temperature of the sensing layer which should be in the requisite temperature range over the heater area, so as to detect the resistive changes as a function of varying concentration of different gases. Hence, their design is a very important aspect. In this paper, we have presented the design and simulation results of a meander micro heater based on three different materials - platinum, titanium and tungsten. The dielectric membrane size is 1.4 mm × 1.6 mm with a thickness of 1.4 μm. Above the membrane, a meander heating film was deposed with a thickness of 100 nm. In order to optimize the geometry, a comparative study by simulating two different heater thicknesses, then two inter track widths has also been presented. Power consumption and temperature distribution were determined in the micro heater´s structure over a supply voltage of 5, 6, and 7 V.

A Study on the Best Applicationsof Infra-Red(IR) Sensors Mounted on the Unmanned Aerial Vehicles(UAV) in Agricultural Crops Field (무인기 탑재 열화상(IR) 센서의 농작물 대상 최적 활용 방안 연구)

  • Ho-Woong Shon;Tae-Hoon Kim;Hee-Woo Lee
    • Journal of the Korean Society of Industry Convergence
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    • v.26 no.6_2
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    • pp.1073-1082
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    • 2023
  • Thermal sensors, also called thermal infrared wavelength sensors, measure temperature based on the intensity of infrared signals that reach the sensor. The infrared signals recognized by the sensor include infrared wavelength(0.7~3.0㎛) and radiant infrared wavelength(3.0~100㎛). Infrared(IR) wavelengths are divided into five bands: near infrared(NIR), shortwave infrared(SWIR), midwave infrared(MWIR), longwave infrared(LWIR), and far infrared(FIR). Most thermal sensors use the LWIR to capture images. Thermal sensors measure the temperature of the target in a non-contact manner, and the data can be affected by the sensor's viewing angle between the target and the sensor, the amount of atmospheric water vapor (humidity), air temperature, and ground conditions. In this study, the characteristics of three thermal imaging sensor models that are widely used for observation using unmanned aerial vehicles were evaluated, and the optimal application field was determined.

Fabrication of Micro Ceramic Thin-Film Type Pressure Sensors for High-Temperature Applications and Its Characteristics (고온용 마이크로 세라믹 박막형 압력센서의 제작과 그 특성)

  • Kim, Jae-Min;Lee, Jong-Choon;Chung, Gwiy-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07b
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    • pp.888-891
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    • 2003
  • This paper describes on the fabrication and characteristics of micro ceramic thin-film type pressure sensors based on Ta-N strain-gauges for high-temperature applications. The Ta-N thin-film strain-gauges are deposited onto thermally oxidized Si diaphragms by RF sputtering in an argon-nitrogen atmosphere($N_2$ gas ratio: 8 %, annealing condition: $900^{\circ}C$, 1 hr.), Patterned on a wheatstone bridge configuration, and use as pressure sensing elements with a high stability and a high gauge factor. The sensitivity is $1.097{\sim}1.21mV/V.kgf/cm^2$ in the temperature range of $25{\sim}200^{\circ}C$ and the maximum non-linearity is 0.43 %FS. The fabricated pressure sensor presents a lower TCR, non-linearity than existing Si piezoresistive pressure sensors. The fabricated micro ceramic thin-film type pressure sensor is expected to be usefully applied as pressure and load sensors that is operable under high-temperature environments.

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Characterization of VO2 thick-film critical temperature sensors by heat treatment conditions (열처리조건에 따른 VO2 후막 급변온도센서의 특성연구)

  • Song, K.H.;Yoo, K.S.
    • Journal of Sensor Science and Technology
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    • v.16 no.6
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    • pp.407-412
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    • 2007
  • For $VO_{2}$ sensors applicable to temperature measurement by using the nature of semiconductor to metal transition, the crystallinity, microstructure, and temperature vs. resistance characteristics were investigated systematically as a function of the annealing condition. The starting materials, vanadium pentoxide ($V_{2}O_{5}$) powders, were mixed with vehicle to form paste. This paste was screen-printed on $Al_{2}O_{3}$ substrates and then $VO_{2}$ thick films were heat-treated at $450^{\circ}C$ to $600^{\circ}C$, respectively, for 1 hr in $N_{2}$ gas atmosphere for the reduction. As results of the temperature vs. resistance property measurements, the electrical resistance of the $V_{2}O_{5}$ sensor in phase transition range was decreased by $10^{3.9}$ order. The presented critical temperature sensor could be used in fire-protection and control systems.

Temperature vs. Resistance Characteristics by Dopants of VO2 Thick-Film Critical Temperature Sensors (불순물 첨가에 따른 VO2 후막 급변온도센서의 온도-저항 특성)

  • Choi, Jung Bum;Kang, Chong Yun;Yoon, Seok-Jin;Yoo, Kwang Soo
    • Journal of Sensor Science and Technology
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    • v.23 no.5
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    • pp.337-341
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    • 2014
  • For various additives doped-$VO_2$ critical temperature sensors using the nature of semiconductor to metal transition, the crystallinity, microstructure, and temperature vs. resistance characteristics were systematically investigated. As a starting material of $VO_2$ sensor, vanadium pentoxide ($V_2O_5$) powders were used, and CaO, SrO, $Bi_2O_3$, $TiO_2$, and PbO dopants were used, respectively. The $V_2O_5$ powders with dopants were mixed with a vehicle to form paste. This paste was silk screen-printed on $Al_2O_3$ substrates and then $V_2O_5$-based thick films were heat-treated at $500^{\circ}C$ for 2 hours in $N_2$ gas atmosphere for the reduction to $VO_2$. From X-ray diffraction analysis, $VO_2$ phases for pure $VO_2$, and CaO and SrO-doped $VO_2$ thick films were confirmed and their grain sizes were 0.57 to $0.59{\mu}m$. The on/off resistance ratio of the $VO_2$ sensor in phase transition temperature range was $5.3{\times}10^3$ and that of the 0.5 wt.% CaO-doped $VO_2$ sensor was $5.46{\times}10^3$. The presented critical temperature sensors could be commercialized for fire-protection and control systems.

Temperature Compensation of Optical FBG Sensors Embedded Tendon for Long-term Monitoring of Tension Force of Ground Anchor (광섬유 센서 내장형 텐던을 이용한 그라운드 앵커의 장기 장력모니터링을 위한 온도보상)

  • Sung, Hyun-Jong;Kim, Young-Sang;Kim, Jae-Min;Park, Gui-Hyun
    • Journal of the Korean Geotechnical Society
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    • v.28 no.5
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    • pp.13-25
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    • 2012
  • Ground anchor method is one of the most popular reinforcing technology for slope in Korea. For the health monitoring of slope which is reinforced by permanent anchor for a long period, monitoring of the tension force of ground anchor is very important. However, since electromechanical sensors such as strain gauge and V/W type load cell are also subject to long-term risk as well as suffering from noise during long distance transmission and immunity to electromagnetic interference (EMI), optical FBG sensors embedded tendon was developed to measure strain of 7-wire strand by embedding FBG sensor into the center king cable of 7-wire strand. This FBG sensors embedded tendon has been successfully applied to measuring the short-term anchor force. But to adopt this tendon to long-term monitoring, temperature compensation of the FBG sensors embedded tendon should be done. In this paper, we described how to compensate the effect in compliance with the change of underground temperature during long-term tension force monitoring of ground anchors by using optical fiber sensors (FBG: Fiber Bragg Grating). The model test was carried out to determine the temperature sensitivity coefficient (${\beta}^{\prime}$) of FBG sensors embedded tendon. The determined temperature sensitivity coefficient ${\beta}^{\prime}=2.0{\times}10^{-5}/^{\circ}C$ was verified by comparing the ground temperatures predicted from the proposed sensor using ${\beta}^{\prime}$ with ground temperatures measured from ground thermometer. Finally, temperature compensations were carried out based on ${\beta}^{\prime}$ value and ground temperature measurement from KMA for the tension force monitoring results of tension type and compression type anchors, which had been installed more than 1 year before at the test site. Temperature compensated tension forces are compared with those measured from conventional load cell during the same measuring time. Test results show that determined temperature sensitivity coefficient (${\beta}^{\prime}$) of FBG sensors embedded tendon is valid and proposed temperature compensation method is also appropriate from the fact that the temperature compensated tension forces are not dependent on the change of ground temperature and are consistent with the tension forces measured from the conventional load cell.

Triboelectric Nanogenerators for Self-powered Sensors

  • Rubab, Najaf;Kim, Sang-Woo
    • Journal of Sensor Science and Technology
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    • v.31 no.2
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    • pp.79-84
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    • 2022
  • Self-powered sensors play an important role in everyday life, and they cover a wide range of topics. These sensors are meant to measure the amount of relevant motion and transform the biomechanical activities into electrical signals using triboelectric nanogenerators (TENGs) since they are sensitive to external stimuli such as pressure, temperature, wetness, and motion. The present advancement of TENGs-based self-powered wearable, implantable, and patchable sensors for healthcare monitoring, human body motion, and medication delivery systems was carefully emphasized in this study. The use of TENG technology to generate electrical energy in real-time using self-powered sensors has been the topic of considerable research among various leading scholars. TENGs have been used in a variety of applications, including biomedical and healthcare physical sensors, wearable devices, biomedical, human-machine interface, chemical and environmental monitoring, smart traffic, smart cities, robotics, and fiber and fabric sensors, among others, as efficient mechanical-to-electric energy conversion technologies. In this evaluation, the progress accomplished by TENG in several areas is extensively reviewed. There will be a discussion on the future of self-powered sensors.

In Line Plastic-Optical-Fiber Temperature Sensor

  • Seo, Hyejin;Shin, Jong-Dug;Park, Jaehee
    • Current Optics and Photonics
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    • v.5 no.3
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    • pp.238-242
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    • 2021
  • In this paper, we present an in line plastic-optical-fiber (POF) temperature sensor based on intensity modulation. The in line POF temperature sensor is composed of a POF, including an in-fiber micro hole filled with reversible thermochromic material, the transmittance of which depends on temperature. The reversible thermochromic material was cobalt chloride/polyvinyl butyral gel. A cobalt chloride solution of concentration 30.8 mM was formulated using 10% water/90% ethanol (v/v) solution, and gelled by dissolving polyvinyl butyral in this solution. Four types of in line POF sensors, with in line micro holes of four different diameters, were fabricated to measure temperature in the range of 25 to 75 ℃. The output optical power of all of these in line POF temperature sensors was inversely proportional to the temperature; the relation between output power and temperature was approximately linear, and the sensitivity was proportional to the diameter of the in-fiber micro hole. The experimental results indicate that an in line POF sensor can be used effectively for measuring moderate temperatures.