• Title/Summary/Keyword: Temperature Sensitivity

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Development of an Optimum Void Detection Chart using Heat Transfer Simulation (열전달 시뮬레이션을 통한 최적공극탐지 차트개발)

  • Choi, Hyun-Ho;Park, Jin-Hyung;Ji, Goang-Seup
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.241-244
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    • 2006
  • It is essential to develop a large capacity, non-contact nondestructive inspection system having high reliability to investigate repaired and strengthened structures. Nowadays, an infrared camera is widely used in non-contact nondestructive inspection system. Because an infrared camera is sensitive to the surrounding environment, it is necessary to improve a sensitivity of thermal image information and a relationship between defects and thermal image information. In this papaer, presented is an optimum void detection chart for the optimum conditions to detect infrared rays from inside and outside defects like voids and cracks in concrete structures using extensive computer simulation. Sensitivity studies are performed with respect to variables influencing the temperature distribution such as heating temperature, heating time, and geometries of defect, etc. It may be stated that it could be successfully utilized for the non-contact nondestructive inspection system to detect defects in concrete structures.

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Fabrication and Characteristics of High-performance Doped-$SnO_2$ Thin Films for Explosive Gas Sensor

  • Chwa, Sang-Ok;Park, Hee-Chan;Kim, Kwang-Ho
    • The Korean Journal of Ceramics
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    • v.2 no.2
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    • pp.83-88
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    • 1996
  • Long term stability, sensitization in air, and gas sensing behaviors of tin oxide films were investigated with doping of antimony and palladium. The tin oxide films were prepared on a Corning glass by reactive rf sputtering method and tested for detection of hydrogen gas. Sb-doping improved a long-term stability in the base resistance of $SnO_2$ film sensor. A small amount of Pd doping caused the optimum sensor operating temperature to reduce and also enhanced the gas sensitivity, compared with the undoped $SnO_2$ film. Gas sensitivity depended largely on the film thickness. The important sensitization reactions for sensor operating were $(O_{2ads})+e^-\;{\rightarrow}\;2(O_{ads})^-$ on the surface of $SnO_2$ film at elevated temperature in air and a followed reaction of hydrogen atoms with $(O_{ads})^-$ ions.

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NOx Sensing Characteristics of the $WO_{3}$-Based Thin-Film Gas Sensors (박막형 $WO_{3}$계 가스센서의 NOx 감도 특성)

  • Yoo, Kwang-Soo
    • Journal of Sensor Science and Technology
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    • v.5 no.5
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    • pp.39-46
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    • 1996
  • The Pd or Pt-doped $WO_{3}$ thin-film NOx sensor was fabricated. The $WO_{3}$-based thin films as a gas-sensing layer were deposited at ambient temperature in a high-vacuum resistance heated evaporator and annealed at $500^{\circ}C$. The gas sensitivity ($R_{gas}/R_{air}$) to 5 ppm $NO_{2}$ measured at the operating temperature of $300^{\circ}C$ was 50 (highest sensitivity) for the 0.5 wt.% $Pt-WO_{3}$ sensor.

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Sensitivity Analysis and Confidence Evaluation for Planar Errors of a Vertical Turning Center (수직형 선반의 평면 오차 민감도 분석 및 신뢰도 평가)

  • 여규환;양승환
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.11
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    • pp.67-75
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    • 1998
  • Geometric and thermal errors are key contributors to the errors of a computer numerically controlled turning center. A planar error synthesis model is obtained by synthesizing 11 geometric and thermal error components of a turning center with homogeneous coordinate transformation method. This paper shows the sensitivity analysis on the temperature change, the confidence evaluation on the uncertainty Of measurement systems, and the error contribution analysis from the planar error synthesis model. Planar error in the z direction was very sensitive to the temperature change. and planar errors in the x and z directions were not affected by the uncertainty of measurement systems. The error contribution analysis ,which is applicable to designing a new turning center, was helpful to find the large error components which affect planar errors of the turning center.

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Inverse Boundary Temperature Estimation in a Two-Dimensional Cylindrical Enclosure Using Automatic Differentiation and Broyden Combined Method (자동미분법과 Broyden 혼합법을 이용한 2차원 원통형상에서의 경계온도 역추정)

  • Kim Ki-Wan;Kim Dong-Min;Baek Seung-Wook
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.30 no.3 s.246
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    • pp.270-277
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    • 2006
  • Inverse radiation problems were solved for estimating boundary temperature distribution in a way of function estimation approach in an axisymmetric absorbing, emitting and scattering medium, given the measured radiative data. In order to reduce the computational time fur the calculation of sensitivity matrix, automatic differentiation and Broyden combined method were adopted, and their computational precision and efficiency were compared with the result obtained by finite difference approximation.. In inverse analysis, the effects of the precision of sensitivity matrix, the number of measurement points and measurement error on the estimation accuracy had been inspected using quasi-Newton method as an inverse method. Inverse solutions were validated with the result acquired by additional inverse methods of conjugate-gradient method or Levenberg-Marquardt method.

Operating Temperature and Time of Rate of Rise Heat Detector (차동식 열감지기의 작동온도와 작동시간)

  • 류호철;이병곤
    • Journal of the Korean Society of Safety
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    • v.9 no.1
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    • pp.61-67
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    • 1994
  • Rate of rise heat detectors that respond to the heat generated in fire plume and alarm when the temperature reaches a specified point, give a great influences to the loss of life and property according to their reaction sensitivity. In this study, simple equations were derived which can be predicted the response time and temperature of the rate of rise heat detector with the results of hot wind tunnel tests and compartment fire experiments.

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A Study On Maximum Torque Of Interior Permanent Magnet Synchronous Motors Considering Temperature Variation (영구자석 동기전동기의 온도변화를 고려한 최대토오크에 관한 연구)

  • Hyun, Dong-Suk;Sim, Joon-Suk;Baek, Kwang-Sun;Kim, Nam-Joon
    • Proceedings of the KIEE Conference
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    • 1989.07a
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    • pp.600-603
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    • 1989
  • In this paper, maximum torque per current ratio of the interior permanent magnet synchronous machines including compensation of Ne-Fe-B magnets in negative temperature sensitivity is described. This compensation can be achieved by measuring of motor temperature only.

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Prediction of the Freshness for Soybean Curd by the Electronic Nose in the Fluctuating Temperature Condition

  • Youn, Aye-Ree;Noh, Bong-Soo
    • Food Science and Biotechnology
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    • v.14 no.3
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    • pp.437-439
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    • 2005
  • Freshness of stored soybean curd as sensitivity ($R_{gas}/R_{air}$) was evaluated at 48-50 hr intervals using electronic nose at regular sequential square-wave temperatures between $4\;-\;10^{\circ}C$. Obtained kinetic data from apparent first principal component score $(PC1)_{app}$ and storage time were used for prediction of freshness. Percentage difference between predicted and actual values of stored soybean curd was less than 8.9% under fluctuating temperature condition.

Technical review of discrimination method between strain and temperature on the FBG sensor (FBG 센서의 온도와 변형률 동시 측정기법 기술 분석)

  • Yoon, Hyuk-Jin
    • Proceedings of the KSR Conference
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    • 2008.11b
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    • pp.574-583
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    • 2008
  • FBG(Fiber Bragg grating)s have shown a great potential for sensing applications, and are easily embedded in materials with a negligible impact on the mechanical properties of the host. However, the use of FBG sensors is limited by their simultaneous dependence on strain and temperature, thus only one parameter can be determined from a single grating. This paper reviews various methods to discriminate between strain and temperature effects. To overcome this cross sensitivity using only embedded optical fibers, a number of techniques have been proposed, most of them relying on the deconvolution of two simultaneous measurements.

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Research to Minimize Endoscope and Objective-lens Sensitivity Using Multi-configurations (다중 구성을 이용한 내시경 및 대물렌즈 광학계 공차 민감도 최소화 설계 기술)

  • Jung, Mee-Suk
    • Korean Journal of Optics and Photonics
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    • v.32 no.6
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    • pp.259-265
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    • 2021
  • Recently, lens manufacturing and assembly technology has greatly improved. However, tight requirements of manufacturing and assembly lead to an increase in cost and manufacturing time, and in some cases the performance of an optical system may deteriorate depending on the operating environment's conditions, such as temperature or vibration. In addition, the use of a compensator is an effective method to reduce sensitivity in an ultra-precision optical system, but in the case of a small lens, such as that in an endoscope, it is difficult to use a compensator due to the size limitation of the lens barrel. Therefore, minimizing lens sensitivity is the most important technology in lens design. For this reason, there have been various attempts to reduce the lens sensitivity, and there is a trend to add functions to reduce the sensitivity in the lens design S/W. In this paper, we introduce a design technology that minimizes lens sensitivity. We first design a lens with quite good performance, then analyze the sensitivity of this lens, make a multi-configuration with high-sensitivity element error, and then reoptimize it. We prove with an example that this design technique is very effective.