• Title, Summary, Keyword: conductivity

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Low-Noise Detector Design for Measuring the Electric Conductivity of Liquids (액체의 전기 전도도 측정을 위한 저잡음 검출기 설계)

  • Kim, Nam Tae
    • Journal of the Institute of Electronics and Information Engineers
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    • v.49 no.9
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    • pp.287-292
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    • 2012
  • In this paper, design of a conductivity detector using a synchronous demodulation is presented to detect the electric conductivity of liquids with low noise. For the purpose, the detector is constructed by the combination of a carrier generator, conductivity detecting cell, and synchronous demodulator. The signal-to-noise ratio(SNR) of the detector is improved by adjusting the frequency bandwidth of the demodulator, whereby infinitesimal conductivity signals can easily be measured under various noise environments. As an application example, a conductivity detector, which is applied to the air monitoring in a fabrication process of semiconductor chips, is designed using the synchronous demodulation. The validity of the design technique is verified by experiments. Since experimental results are shown to approach the design performance of the detector, the synchronous demodulation proves to be useful to the design of a conductivity detector for measuring the infinitesimal electric conductivity of liquids.

Proposal for the Estimation of the Hydraulic Conductivity of Porous Asphalt Concrete Pavement using Regression Analysis (단순회귀분석에 의한 배수성 아스팔트의 투수계수 산정모델 제안)

  • Jang, Yeongsun;Kim, Dowan;Mun, Sungho;Jang, Byungkwan
    • International Journal of Highway Engineering
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    • v.15 no.3
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    • pp.45-52
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    • 2013
  • PURPOSES : This study is to construct the regression models of drainage asphalt concrete specimens and to provide the appropriate coefficients of hydraulic conductivity prediction models. METHODS: In terms of easy calculation of the hydraulic conductivity from porosity of asphalt concrete pavement, the estimation model of hydraulic conductivity was proposed using regression analysis. 10 specimens of drainage asphalt concrete pavement were made for measurement of the hydraulic conductivity. Hydraulic conductivity model proposed in this study was calculated by empirical model based on porosity and the grain size. In this study, it shows the compared results from permeability measured test and empirical equation, and the suitability of proposed model, using regression analysis. RESULTS: As the result of the regression analysis, the hydraulic conductivity calculated from the proposal model was similar to that resulted from permeability measured test. Also result of RMSE (Root Mean Square Error) analysis, a proposed regression model is resulted in more accurate model. CONCLUSIONS: The proposed model can be used in case of estimating the hydraulic conductivity at drainage asphalt concrete pavements in fields.

Studies on Polymer Coating in Soybean Seeds 1. Difference of Electrolyte Leaching of Polymeric Coating Soybean Seed (대두종자의 polymer coating 연구 1. polymer coating 종자의 conductivity 차이)

  • 이성춘
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.39 no.2
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    • pp.158-164
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    • 1994
  • These experiment were conducted to evaluate the environmentally acceptable polymers, and 10 polymers were used in these study, and to investigate conductivity, germination percentage, water uptake of polymeric coating soybean seed. The conductivity of polymeric coating seed is higher than that of none coating seed and the highest conductivity was obtained with waterlock coating seed among the 10 polymer coating seed. As the soaking time was long, the conductivity was increased. The conductivity of large seed was higher than that of small seed, and that of long period storage seed was higher than that of short period storage seed. The effects of seed coating polymers on uptake water were various, and daran 8600 inhibited uptake water of low quality seed. The waterlock, captan, klucel and sacrust was rised germination percentage, and daran 8600 was declined germination percentage, and the effect of coating polymers on germination percentage of low quality seed was higher than that of high quality seed.

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Applicability of Electrical Conductivity Monitoring Technique for Soil-bentonite Barrier (흙-벤토나이트월에 대한 전기전도도 모니터링 기법의 적용성 평가)

  • Oh, Myoung-Hak;Yoo, Dong-Ju;Kim, Yong-Sung;Park, Jun-Boum
    • Journal of the Korean Geotechnical Society
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    • v.23 no.7
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    • pp.47-55
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    • 2007
  • In this study, applicability of electrical conductivity monitoring technique for containment barrier such as soil-bentonite wall was evaluated. Laboratory tests including permeability tests and column tests were performed to understand variations in electrical conductivity at different bentonite contents, hydraulic conductivities, and heavy metal concentrations. The electrical conductivity of compacted soil-bentonite mixtures was found to increase proportionally with bentonite content. Accordingly, the hydraulic conductivity of compacted soil-bentonite mixtures which decreases linearly with increasing bentonite content was found to have an inversely proportional relationship with the electrical conductivity. In column tests, electrical conductivity breakthrough curves and concentration breakthrough curves were simultaneously obtained. These results indicated that electrical conductivity measurement can be an effective means of detecting heavy metal transport at the desired locations within barriers and verifying possible contaminant leakage. Experimental results obtained from this study showed that the electrical conductivity measurement can be a promising tool for monitoring of containment barrier.

Effects of Column Boundary Flow and Surfactant Contents on Soil Hydraulic Conductivity (토양 칼럼의 경계흐름과 계면활성제가 수리전도도에 미치는 영향연구)

  • Jeong, Seung-Woo;Ju, Byung-Kyu
    • Journal of the Korea Organic Resources Recycling Association
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    • v.17 no.1
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    • pp.73-79
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    • 2009
  • The hydraulic conductivity of porous media is the most important property in soil characteristics. The hydraulic conductivity is determined by outdoor and indoor methods. Indoor methods normally use soil columns for flow test. Assumption of the column test is that fluid one-dimensionally flows through the column. However, fluids may flow toward the wall of the column, resulting in "boundary flow". This study investigated the effect of boundary flow on the hydraulic conductivity by using a permeameter excluding boundary flow. The results showed that the hydraulic conductivity excluding boundary flow was much smaller than the hydraulic conductivity employing the conventional determination method. This study also investigated the effects of particle size and surfactant on the hydraulic conductivity. As the particle size increased, the hydraulic conductivity was increased. The hydraulic conductivity was reduced by increasing surfactant concentration. The result showed that the viscosity of fluid significantly affected the determination of hydraulic conductivity.

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A study on electric field computation of dielectric analysis model with the conductivity on its surface (표면에 도전율을 갖는 유전체 해석모델의 전계계산에 관한 연구)

  • Kim, Hyeong-Seok;Lee, Ki-Sik;Hahn, Song-Yop
    • Proceedings of the KIEE Conference
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    • pp.6-8
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    • 1995
  • In this paper, we study the computation of the electric field of dielectric analysis models with the conductivity on its surface. The finite element formulation describes a sinusoidal electrodynamic field computation. One term is added to this functional in order to take the conductivity on its surface into accounts. The electric field computations of the dielectric analysis model are done first with the surface conductivity and second with the volume conductivity. Also, it is shown that a surface conductor with sufficiently large conductivity can be substituted with a floating equipotential line. This method is applied to an insulator in arbitrary shape with the conductivity on its surface.

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Impact of Phonon Dispersion on Thermal Conductivity Model (포논 분산이 열전달 모델에 미치는 영향)

  • Chung, Jae-Dong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.8
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    • pp.1165-1173
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    • 2003
  • The effects of (1) phonon dispersion on thermal conductivity model and (2) differentiation of group velocity and phase velocity are examined for germanium. The results show drastic change of thermal conductivity regardless of the same relaxation time model. Also the contribution of transverse acoustic (TA) phonon and longitudinal acoustic (LA) phonon on the thermal conductivity at high temperatures is reassessed by considering more rigorous dispersion model. Holland model, which is commonly used for modeling thermal conductivity, underestimates the scattering rate for TA phonon at high frequency. This leads the conclusion that TA is dominant heat transfer mode at high temperatures. But according to the rigorous consideration of phonon dispersion, the reduction of thermal conductivity is much larger than the estimation of Holland model, thus the TA at high frequency is expected to be no more dominant heat transfer mode. Another heat transfer mechanism may exist at high temperatures. Two possible explanations we the roles of (1) Umklapp scattering of LA phonon at high frequency and (2) optical phonon.

A Study on the Effective Hydraulic Conductivity of an Anisotropic Porous Medium

  • Seong, Kwanjae
    • Journal of Mechanical Science and Technology
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    • v.16 no.7
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    • pp.959-965
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    • 2002
  • Effective hydraulic conductivity of a statistically anisotropic heterogeneous medium is obtained for steady two-dimensional flows employing stochastic analysis. Flow equations are solved up to second order and the effective conductivity is obtained in a semi-analytic form depending only on the spatial correlation function and the anisotropy ratio of the hydraulic conductivity field, hence becoming a true intrinsic property independent of the flow field. Results are obtained using a statistically anisotropic Gaussian correlation function where the anisotropy is defined as the ratio of integral scales normal and parallel to the mean flow direction. Second order results indicate that the effective conductivity of an anisotropic medium is greater than that of an isotropic one when the anisotropy ratio is less than one and vice versa. It is also found that the effective conductivity has upper and lower bounds of the arithmetic and the harmonic mean conductivities.

An Analytical Model for Predicting the Effective Thermal Conductivity of Woven Wire Wick Structure

  • Lee, Jin-Sung;Kim, Chul-Ju
    • International Journal of Air-Conditioning and Refrigeration
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    • v.10 no.2
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    • pp.72-78
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    • 2002
  • Woven wire wick is a very effective structure because of its easiness to insert inside of pipe for a miniature heat pipe. The present study was conducted to predict the porosity and the effective thermal conductivity of liquid-saturated woven wire wick. The porosity and the effective thermal conductivity of the evaporator region indicate different values from those of the condenser region due to the existence of non-flow region. The minimum value of the effective thermal conductivity indicates on condition of the $\theta$=$45^{Wcirc}$ and the values of the effective thermal conductivity increases symmetrically centering around the minimum value. The values of the effective thermal conductivity in the evaporator region at the angle of $45^{Wcirc}$ indicate about 60~80% higher than those in the condenser region for various combinations of copper, and stainless with water and ethanol.

A study on the Thermal Conductivity of Kaolin in Korea (우리나라 고령토의 열전도계수에 관한 연구)

  • Pak, H.Y.;Lee, H.J.;Kang, Kun
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.1 no.2
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    • pp.162-172
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    • 1989
  • The steady one dimensional heat flow method was used for the measurement of thermal conductivity of kaolin. The effects of the classification, density and moisture content on the thermal conductivity were studied experimentally for the 9 classes of kaolin in Korea. As the results of this study, it was found that the classification did not effect the thermal conductivity, and the conductivity increased as the density and moisture content increased. The correlation equation of the thermal conductivity as a function of the density increase rate was found and the values for the thermal conductivity as a function of moisture content were recommended.

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