• Title/Summary/Keyword: temperature sensitivity

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Redox Reaction on Polarization Curve Variations of Polymer with Enzymes

  • Park, Chil-Nam
    • Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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    • v.4 no.3
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    • pp.165-171
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    • 2000
  • Experiments were carried out to measure variations in the oxidation potential and current density using the polarization curves of polycarbonate. The results were then examined to identify the influences affecting the oxidation potential related to various conditions, such as temperature, pH, and oxydase(citrate and lipase). The lines representing the active anodic and cathodic dissolution shifted only slightly in the potential direction relative to temperature, pH, and the effect of the enzyme. The Tafel slope for the anodic and cathodic dissolution was determined such that the reversibility polarization was indicated as being effected by various conditions. The slope of the polarization curves describing the active-to-passive transition region shifted noticeably in their direction. Also, by varying the conditions, the optimum conditions for the most ready transform were identified, including temperature, pH, oxidation rate, and resistance of oxidation potential. The critical oxidation sensitivity(I(sub)r/I(sub)f) of the anodic current density peak and maximum passive current density was also determined, which is used in measuring the critical corrosion sensitivity of a polycarbonate.

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The Effect of Temperature on Corrosion of Absorption Refrigeration Systems Using $LiBr-H_2O$ Working Fluids ($LiBr-H_2O$계 흡수식냉동기의 부식에 미치는 온도의 영향)

  • 임우조;정기철
    • Journal of Advanced Marine Engineering and Technology
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    • v.26 no.1
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    • pp.125-131
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    • 2002
  • This paper was studied on the effect of temperature on corrosion of absorption refrigeration systems using $LiBr-H_2O$ working fluids. In the fresh water and 62 % lithium bromide solution at $70^{\circ}C$, polarization test of SS 400, Cu(C1220T-OL) and Al-Ni bronze was carried out. And polarization behavior, polarization resistance characteristics, corrosion rate(mmpy) and corrosion sensitivity of materials forming absorption refrigeration systems was considered. The main results are as following: (1) As the experimental temperature increase, the change of corrosion rate of Al-Ni bronze become duller than SS 400 and Cu in 62% lithium bromide solution. (2) According as corrosion environment is changed from fresh water to 62% lithium bromide solution, potential change of Cu and Al-Ni bronze become less noble than SS 400. (3) The corrosion sensitivity of Al-Ni bronze was duller than that of Cu and SS 400 in 62% LiBr solution.

Spectroscopic properties of Er3+/Yb3+ co-doped fluorophosphate glasses for NIR luminescence and optical temperature sensor applications

  • Linganna, K.;Agawane, G.L.;In, Jung-Hwan;Park, June;Choi, Ju H.
    • Journal of Industrial and Engineering Chemistry
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    • v.67
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    • pp.236-243
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    • 2018
  • A series of $Er^{3+}/Yb^{3+}$ co-doped fluorophosphate glasses with varying $YbF_3$ concentration were prepared by a high temperature melt quenching technique. Absorption and emission cross-sections were determined by using the McCumber theory. The larger emission cross-section ($9.86{\times}10^{-21}cm^2$) and longer fluorescence lifetime (12.37 ms) were obtained for the $^4I_{13/2}{\rightarrow}^4I_{15/2}$ transition of ABS3Er4Yb glass. The sensitivity and temperature of the maximum sensitivity were evaluated by the fluorescence intensity ratio method from the measured upconversion spectra. The results were discussed and compared to the other reported glasses.

Influence of Temperature on the Survival, Growth and Sensitivity of Benthic Amphipods, Mandibulophoxus mai and Monocorophium acherusicum (국내산저서단각류 Mandibulophoxus mai와 Monocorophium acherusicum의 생존, 성장 및 민감도에 대한 온도의 영향)

  • Lee Kyu-Tae;Lee Jung-Suk;Kim Dong-Hoon;Kim Chan-Kook;Park Kun-Ho;Kang Seong-Gil;Park Gyung-Soo
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.8 no.1
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    • pp.9-16
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    • 2005
  • A series of experiments was conducted to evaluate the effects of temperature on the survival, growth and sensitivity of the benthic amphipods, Mandibuluphoxus mai and Monocnrophium acherusicum, which have been recently developed as new sediment toxicity testing species in Korea. The biological performance for each amphipod species was determined by the survival and growth rates at different water temperatures. The influence of temperature on the sensitivity to reference toxicant, Cd, was determined by the comparison of survival rates of amphipods exposed to control and Cd-spiked seawater at different temperatures. Temperature significantly influenced on the survival, growth and Cd sensitivity of both amphipods. Tolerable ranges of temperature for the >80% individuals of both M. mai and M. acherusicum with sediment substrates were mostly overlapped (13 to 22℃). The daily growth rates of M. mai and M. acherkisicum increased proportionally with temperature up to 20℃ and 25℃. respectively. Similarly, the sensitivities of M. mai and M. acheyusicum to Cd increased with temperature up to 20℃ and 15℃, respectively. Overall results showed that temperature is a substantially important factor potentially influencing the results of lethal and sublethal bioassays using the amphipods. Therefore, defining the adequate ranges of experimental temperature for the toxicity testing species is the pre-requisite for the development of standardized bioassay protocols.

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Sensitivity Enhancement of Polyaniline Sensor to Volatile Organic Compounds (휘발성유기화합물가스에 대한 폴리아닐린 센서의 감도 향상)

  • Yu, Joon-Boo;Liu, Fei;Lim, Jeong-Ok;Byun, Hyung-Gi;Huh, Jeung-Soo
    • Korean Journal of Materials Research
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    • v.17 no.8
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    • pp.433-436
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    • 2007
  • Nano-structured polyaniline have been synthesized by interfacial polymerization method at room temperature. An aqueous solution of aniline in chloroform and another solution of ammonium peroxydisulfate in doping acid were prepared at different times terminated with methanol at room temperature. SEM, UV-vis were used to characterize the polyaniline with regard to their morphology and structure. The diameter and length of polyaniline can be controlled by the reaction time. Nano-structured polyaniline were found to have superior sensitivity for volatile organic compounds(VOCs). As the reaction time to increase from 30minute to 2hours the sensitivity were decreased to VOCs vapors. The sensitivity of Nano-structured polyaniline sensor appeared to VOCs better than the sensitivity of chemical synthesis sensors. The sensitivity of Nano-structured polyaniline sensor improved benzene vapors.

Uncertainty in Potentiodynamic Polarization Resistance Measurement (동전위 분극저항 측정에서의 불확도)

  • Kim, Jong Jip
    • Corrosion Science and Technology
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    • v.8 no.5
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    • pp.193-196
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    • 2009
  • For the estimation of uncertainty in potentiodynamic polarization resistance measurement, the type A uncertainty was measured using type 316 stainless steel in an acidified NaCl solution. Sensitivity coefficients were determined for measurand such as scan rate of potential, temperature of solution, concentration of NaCl, concentration of HCl, surface roughness of specimen and flow rate of purging gas. Sensitivity coefficients were large for the measurand such as the scan rate of potential, temperature of solution and roughness of specimen. However, the sensitivity coefficients were not the major factors influencing the combined standard uncertainty of polarization resistance due to the low values of uncertainty in measurements of the measurands. A major influencing factor was the concentration of NaCl. The value of type A uncertainty was 1.1 times the value of type B uncertainty, and the combined standard uncertainty was 10.5 % of the average value of polarization resistance.

Electrical Conductivity, Flammable Gas Response and Humidity Effect of Pporous ZnO (다공질 ZnO의 전기적 특성, 환원성 가스 감응 특성 및 습도의 영향)

  • 윤당혁;최경만
    • Journal of the Korean Ceramic Society
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    • v.32 no.11
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    • pp.1283-1291
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    • 1995
  • The electrical conductivity, flammable gas response and their humidity effect of porous ZnO, added with 5wt% corn starch as the fugitive phase, were examined. Porous ZnO showed different conductivity curves during increasing and decreasing temperature, and its electrical conductivity decreased rapidly by desorption of OH- between 20$0^{\circ}C$ and 35$0^{\circ}C$ when the temperature increased in dry air. The CO gas sensitivity of starchadded ZnO samples was higher than that of ZnO without starch addition. The sensitivity of porous, starchadded ZnO to 200ppm CO gas was much less in humid atmosphere than in dry atmosphere since water vapor increased the conductivity of porous ZnO in air, but decreased the conductivity in CO. Maximum sensitivity to 200 ppm CO gas balanced by air was about 100 in dry atmosphere and about 15 in RH 23% atmosphere.

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Sensitivity Analysis of the Atmospheric Dispersion Modeling through the Condition of Input Variable (입력변수의 조건에 따른 대기확산모델의 민감도 분석)

  • Chung Jin-Do;Kim Jang-Woo;Kim Jung-Tae
    • Journal of Environmental Science International
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    • v.14 no.9
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    • pp.851-860
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    • 2005
  • In order to how well predict ISCST3(lndustrial Source Complex Short Term version 3) model dispersion of air pollutant at point source, sensitivity was analysed necessary parameters change. ISCST3 model is Gaussian plume model. Model calculation was performed with change of the wind speed, atmospheric stability and mixing height while the wind direction and ambient temperature are fixed. Fixed factors are wind direction as the south wind(l80") and temperature as 298 K(25 "C). Model's sensitivity is analyzed as wind speed, atmospheric stability and mixing height change. Data of stack are input by inner diameter of 2m, stack height of 30m, emission temperature of 40 "C, outlet velocity of 10m/s. On the whole, main factor which affects in atmospheric dispersion is wind speed and atmospheric stability at ISCST3 model. However it is effect of atmospheric stability rather than effect of distance downwind. Factor that exert big influence in determining point of maximum concentration is wind speed. Meanwhile, influence of mixing height is a little or almost not.

Sensitivity Analyses of the Meteorological Factors in the Estimation of Evapotranspiration Rates (증발산량 산정에 있어서 기상학적 요인들의 민감도 해석)

  • 임창수
    • Journal of Environmental Science International
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    • v.5 no.5
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    • pp.657-662
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    • 1996
  • Meteorological and flux data measured from semiarid watersheds (Lucky Hills and Kendall) during the summer rainy and winter periods were used to study the sensitivity of the those variables used in the estimation of evapotranspiration rates. Relative sensitivity was examined to compare the importance of four meteorological and flux variables (net radiation wind speed, air temperature, and relative humidity) on Penman potential evapotranspiration (PET) estimation. The study results show that variations in Penman PET rates during the summer rainy period at both watersheds appears to be controlled by air temperature adn net radiation. During the winter period at both watersheds, wariations in Penman PET rates appears to be controlled by relative humidity and air temperature.

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Fabrication of NO sensor integrated SiC micro heaters for harsh environments and its characteristics (SiC 마이크로 히터가 내장된 극한 환경용 NO 센서의 제작과 특성)

  • Kim, Kang-San;Chung, Gwiy-Sang
    • Journal of Sensor Science and Technology
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    • v.19 no.3
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    • pp.197-201
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    • 2010
  • This paper describes the fabrication and characteristics of a NO sensor using ZnO thin film integrated 3C-SiC micro heater based on polycrystalline 3C-SiC thin film of operation in harsh environments. The sensitivity, response time, and operating properties in high temperature and voltages of NO sensors based SiC MEMS are measured and analyzed. The sensitivity of device with pure ZnO thin film at the heater operating power of 13.5 mW ($300^{\circ}C$) is 0.875 in NO gas concentration of 0.046 ppm. In the case of Pt doping, the sensitivity of at power consumption of 5.9 mW ($250^{\circ}C$) was 1.92 at same gas flow rate. The ZnO with doped Pt was showed higher sensitivity, lower working temperature and faster adsorption characteristics to NO gas than pure ZnO thin film. The NO gas sensor integrated SiC micro heater is more strength than others in high voltage and temperature environments.