• Title/Summary/Keyword: Temperature Sensitivity

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High sensitivity ethanol gas sensors (고감도 에탄올 가스 센서)

  • Choi, Dong-Han
    • Journal of Sensor Science and Technology
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    • v.16 no.5
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    • pp.355-360
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    • 2007
  • Highly sensitive thick film ethanol gas sensors based on a nanocrystalline $In_{2}O_{3}$ were fabricated by painting method on alumina substrates. The crystal structure of the $In_{2}O_{3}$ powder was characterised by XRD analysis. The microstructure of the films were characterised using FE-SEM. The experimental results of the ethanol gas sensing characteristics indicated that the undoped $In_{2}O_{3}$ thick film has a high sensitivity. The sensitivity of the film heat treated at $400^{\circ}C$ for 2 hrs. was as high as 32.73 at an operating temperature of $200^{\circ}C$ to 1000 ppm ethanol gas in air.

Improvement of Sensitivity in Porous Silicon Alcohol Gas Sensors by UV Light (자외선조사에 의한 다공질 실리콘 알코올 센서의 감도 개선)

  • Kim, Seong-Jin;Choe, Bok-Gil
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.48 no.9
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    • pp.676-680
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    • 1999
  • To do breath alcohol measurement, a sensor is necessary that it can detect low alcohol gas concentration of 0.01% at least. In this work, a capacitance-type alcohol gas sensor using porous silicon layer is developed to measure low alcohol gas concentration. The sensor using porous silicon layer has some sensitivity at room temperature by very large effective surface area, but there is still much room for improvement. In this experiment, we measured the capacitance of the sensor under 254 nm UV light on the porous silicon layer, in which alcohol solution was kept in a flask at 25, 35, and $45^{\circ}C$ by a heater. As the result, the improvement of sensitivity by illuminating UV light was observed. The increasing rate of the capacitance was shown to be double more than those measured under UV-off state. It is supposed that UV light activates response of the oriental and interfacial polarizations which have slow relaxation time for AC field.

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Fabrication of a SOI hall sensor using Si-wafer direct bonding technology and its characteristics (실리콘기판 직접접합기술을 이용한 SOI 홀 센서의 제작과 그 특성)

  • 정귀상
    • Electrical & Electronic Materials
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    • v.8 no.2
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    • pp.165-170
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    • 1995
  • This paper describes the fabrication and characteristics of a Si Hall sensor fabricated on a SOI (Si-on-insulator) structure. The SOI structure was formed by SDB(Si-wafer direct bonding) technology and the insulator of the SOI structure was used as the dielectrical isolation layer of a Hall sensor. The Hall voltage and sensitivity of the implemented SDB SOI Hall sensors showed good linearity with respect to the applied magnetic flux density and supplied current. The product sensitivity of the SDB SOI Hall sensor was average 600V/A.T and its value has been increased up to 3 times compared to that of bulk Si with buried layer of 10.mu.m. Moreover, this sensor can be used at high-temperature, high-radiation and in corrosive environments.

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Fabrication and ethanol gas sensing characteristics of the thick film ethanol gas sensors (후막형 에탄올 가스 감지소자의 제조 및 특성)

  • Choi, Dong-Han
    • Journal of Sensor Science and Technology
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    • v.16 no.6
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    • pp.428-433
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    • 2007
  • $SnO_{2}$-based thick film ethanol gas sensors were fabricated on alumina substrates and their ethanol gas sensing characteristics were investigated. The film sintered at $400^{\circ}C$ for 2 hrs. showed the highest sensitivity to ethanol gas and the sensitivity of the film to 1000 ppm ethanol gas in air was 97 % at an operating temperature of $250^{\circ}C$. The addition of $Fe_{2}O_{3}$ to $SnO_{2}$ enhanced the sensitivity by changing the type and number of surface acidic/basic sites.

Short-Term Load Forecasting Using Neural Networks and the Sensitivity of Temperatures in the Summer Season (신경회로망과 하절기 온도 민감도를 이용한 단기 전력 수요 예측)

  • Ha Seong-Kwan;Kim Hongrae;Song Kyung-Bin
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.54 no.6
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    • pp.259-266
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    • 2005
  • Short-term load forecasting algorithm using neural networks and the sensitivity of temperatures in the summer season is proposed. In recent 10 years, many researchers have focused on artificial neural network approach for the load forecasting. In order to improve the accuracy of the load forecasting, input parameters of neural networks are investigated for three training cases of previous 7-days, 14-days, and 30-days. As the result of the investigation, the training case of previous 7-days is selected in the proposed algorithm. Test results show that the proposed algorithm improves the accuracy of the load forecasting.

C3H8 Gas Sensitivity of Pd, Pt-$SnO_2$ Gas Sensor with Varying Impregnation Method (함침 방법의 차이에 따른 Pd, Pt-$SnO_2$의 프로판 가스 감응성 변화)

  • 이종흔;박순자
    • Journal of the Korean Ceramic Society
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    • v.27 no.5
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    • pp.638-644
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    • 1990
  • The C3H8 gas sensitivities of SnO2, Pd-SnO2, Pt-SnO2 gas sensor are looked over with the impregnation method of PdCl2, H2PtCl6 solution on SnO2. The Cl- ion due to incomplete decomposition of PdCl2 at 80$0^{\circ}C$ for 30 min decrease the C3H8 gas sensitivity of SnO2, and the sensitivity is increased by the impreganation of H2PtCl6 solution on SnO2 because of its lower decomposition temperature compared with PdCl2. The C3H8 gas sensitivities of Pd-SnO2, Pt-SnO2 impregnated slightly after 1st sintering are larger than that of pure SnO2 sensor because very small amount of Cl- ion exist in sample due to smaller amount of impregnaiton.

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The Effect of Alloying Elements on Weldability and Corrosion Resistance of Austenitic Stainless Steels(I) (오스테나이트계 스테인리스강의 용접성과 내식성에 미치는 합금원소의 영향(I) - 응고균열 감수성을 중심으로 -)

  • Jeong, Ho-Shin;Lee, Yun-Young;Bae, Dong-Soo
    • Journal of Welding and Joining
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    • v.30 no.3
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    • pp.57-65
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    • 2012
  • The interest of austenitic heat resistant stainless steels containing high Si has increased because they have higher resistance of oxidation and higher strength at high temperature than STS 310. This study carried out Varestraint test for evaluation of solidification cracking sensitivity of 14 different stainless steels. As a result of Varestraint test, all specimens solidified as primary ferrite, and solidification crack sensitivity increased with adding $N_2$ to shielding gas. Nb and W had beneficial effect on solidification crack resistance in case of less than FN 2 containing, but crack sensitivity increased with Nb and W in case of more than FN 2. Ce had beneficial effect on solidification crack resistance but impaired weld bead appearance.

A Case Report of Cold Sensitivity of Hands and Feet Patient (수족냉증 환자 치험 1례)

  • Cho, Jun-Young;Kim, Jin-Woo;Park, Kyoung-Sun;Lee, Chang-Hoon;Cho, Jung-Hoon;Jang, Jun-Bock;Lee, Kyung-Sub;Lee, Jin-Moo
    • The Journal of Korean Obstetrics and Gynecology
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    • v.24 no.3
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    • pp.195-202
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    • 2011
  • Purpose: The purpose of this study is to report the effect of Traditional Korean Medicine(TKM) on cold sensitivity of hands and feet. And we wanted that cold sensitivity of hands and feet was measured objectively and diagnosed definitely using Digital Infrared Thermographic Imaging(DITI). Methods: The patient in this case was a 29-year-old female. The chief complaint was cold sensitivity of hands and feet. We treated her by TKM and evaluated the progress of symptoms by DITI. And then we compared DITI before treatment and after treatment. Results: After TKM treatment, the differences of temperature of hands and feet were decreased on DITI, respectively. Conclusion: TKM treatment is effective on cold sensitivity of hands and feet. And DITI would be valid to measure for treatment's effect of cold sensitivity of hands and feet.

Typhoon Wukong (200610) Prediction Based on The Ensemble Kalman Filter and Ensemble Sensitivity Analysis (앙상블 칼만 필터를 이용한 태풍 우쿵 (200610) 예측과 앙상블 민감도 분석)

  • Park, Jong Im;Kim, Hyun Mee
    • Atmosphere
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    • v.20 no.3
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    • pp.287-306
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    • 2010
  • An ensemble Kalman filter (EnKF) with Weather Research and Forecasting (WRF) Model is applied for Typhoon Wukong (200610) to investigate the performance of ensemble forecasts depending on experimental configurations of the EnKF. In addition, the ensemble sensitivity analysis is applied to the forecast and analysis ensembles generated in EnKF, to investigate the possibility of using the ensemble sensitivity analysis as the adaptive observation guidance. Various experimental configurations are tested by changing model error, ensemble size, assimilation time window, covariance relaxation, and covariance localization in EnKF. First of all, experiments using different physical parameterization scheme for each ensemble member show less root mean square error compared to those using single physics for all the forecast ensemble members, which implies that considering the model error is beneficial to get better forecasts. A larger number of ensembles are also beneficial than a smaller number of ensembles. For the assimilation time window, the experiment using less frequent window shows better results than that using more frequent window, which is associated with the availability of observational data in this study. Therefore, incorporating model error, larger ensemble size, and less frequent assimilation window into the EnKF is beneficial to get better prediction of Typhoon Wukong (200610). The covariance relaxation and localization are relatively less beneficial to the forecasts compared to those factors mentioned above. The ensemble sensitivity analysis shows that the sensitive regions for adaptive observations can be determined by the sensitivity of the forecast measure of interest to the initial ensembles. In addition, the sensitivities calculated by the ensemble sensitivity analysis can be explained by dynamical relationships established among wind, temperature, and pressure.

Polarization-Maintaining Photonic-Crystal-Fiber-based Polarimetric Strain Sensor with a Short Sensing Head (짧은 센서부를 가진 편광유지 광자결정 광섬유 기반 편광 간섭형 스트레인 센서)

  • Noh, Tae Kyu;Lee, Yong Wook
    • Korean Journal of Optics and Photonics
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    • v.25 no.3
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    • pp.131-136
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    • 2014
  • In this paper we have implemented a temperature-insensitive polarimetric fiber strain sensor based on a Sagnac birefringence interferometer composed of a short polarization-maintaining photonic crystal fiber (PM-PCF), a 3-dB fiber coupler, and polarization controllers. The PM-PCF used as a sensor head was 2 cm long, which is the shortest length for a sensing element compared to other polarimetric fiber strain sensors using a PM-PCF. The proposed sensor showed a strain sensitivity of ${\sim}0.87pm/{\mu}{\varepsilon}$ with a strain measurement range from 0 to $8m{\varepsilon}$. The temperature sensitivity was also investigated and measured as approximately $-12pm/^{\circ}C$, when ambient temperature changed from 30 to $100^{\circ}C$. This temperature sensitivity is about 82 times smaller than that of conventional polarization-maintaining fiber (approximately $-990pm/^{\circ}C$). In particular, from a practical perspective we have experimentally and theoretically confirmed that the wavelength selected for the indicator dip location does not make a significant difference in the strain sensitivity.