• Title/Summary/Keyword: HIgh viscosity

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A study on properties of ultra high strength concrete of above 100MPa - fluidity and rheology properties (100MPa급 이상의 초고강도 콘크리트의 특성에 관한 연구 - 유동성 및 rheology 특성)

  • Seo, Il;Lee, Jin-Woo;Park, Hee-Gon;Bae, Yeon-Ki;Cho, Sung-Hyun;Lee, Han-Seung
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.317-320
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    • 2008
  • In recent year, the ultra high strength concrete has highly increased and been used in many parts of the world. However, the viscosity of the ultra high strength concrete is high because of a low water to binder ratio (w/b). So that in this pater, the shear stress and the shear strain rate are directly measured by the viscometer in order to estimate the rheological properties of the ultra high strength concrete and a linear regression analysis was carried out to determine the plastic viscosity and the yield stress as slope. According to the test results, the yield stress and plastic viscosity are correlated to slump-flow, V-funnel flow time, O-lot flow time

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Development of High Viscosity Pulping Method for Korean Paper (I) - Atmospheric Pressure Pulping Characteristics of Paper Mulberry White Bast - (고점도 펄프를 위한 새로운 한지 펄프화법의 개발(제1보) - 닥나무 백피의 상압 펄프화 특성 -)

  • Lee, Sang-Hyun;Choi, Tae-Ho
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.43 no.2
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    • pp.57-65
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    • 2011
  • Pulping of paper mulberry (Broussonetia kazinoki) white bast has been examined by novel atmospheric pressure pulping methods. The viscosity of pulp has been found to be highly sensitive and variable with pulping methods. Therefore, selections of pulping chemicals and conditions are very important. Two kinds of pulping procedures were employed for the high viscosity pulp manufacturing. The one is ammonium oxalate treatment and the other is sodium chlorite and acetic acid treatment. Not only chemical components and pulp yields which of paper mulberry white bast but also water retention value (WRV), whiteness index, yellowness index, and colors of every pulp were examined. The hot water, 1% NaOH, and ethanol-benzene extractives which of paper mulberry white bast were 4.48%, 28.45%, and 2.84%, respectively. The contents of holocellulose, lignin, and ash were 90.66%, 1.05%, and 2.18%, respectively. In the pulp yields, group 1 which treated with only ammonium oxalate were 77.04-81.71%, group 2 which treated with ammonium oxalate and acidified sodium chlorite separately and washed between first and second stages were 64.15-83.90%, group 3 which treated with ammonium oxalate and acidified sodium chlorite separately and not washed between first and second stages were 57.35-73.17%, and group 4 which treated with mixed ammonium oxalate and acidified sodium chlorite were 66.58-68.43%. The pulps treated with acidified sodium chlorite showed high whiteness index, but the pulps treated with only ammonium oxalate showed high yellowness index. Variations in the combinations of treatments resulted in different pulp characteristics.

Evaluation of High-Viscosity Grouting Injection Perfomance for Reinforcement of Rock Joint in Deep -Depth Tunnels (대심도 터널 암반 절리 보강을 위한 고점도 그라우팅 주입 성능 평가)

  • Inkook Yoon;Junho Moon;Younguk Kim
    • Journal of the Korean GEO-environmental Society
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    • v.25 no.5
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    • pp.15-19
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    • 2024
  • This study aimed to develop high-efficiency grouting techniques under deep-depth conditions by experimentally verifying the applicability of various injection materials. Particle size analysis and injection model experiments were conducted with Ordinary Portland Cement (OPC) and Micro Cement (MC) to evaluate the injection performance of each material. Using Barton's Cubic Network theory, the rock fracture spacing was calculated for domestic deep-depth standards, specifically below 40 meters underground. The analysis of particle size passability under selected conditions showed that MC could pass through the rock fracture gaps, while OPC could not. According to the results of the injection model experiments using experimental devices and area calculation software, OPC failed in injection due to its larger particle size, whereas MC was capable of injection even under high-viscosity conditions. Based on these findings, the study quantitatively and visually derived the applicability of grouting materials under deep-depth conditions, and high-viscosity MC material is expected to be effective for waterproofing enhancement in deep-depth rock fracture surfaces.

Renewable Low-viscosity Dielectrics Based on Vegetable Oil Methyl Esters

  • Yu, Hui;Yu, Ping;Luo, Yunbai
    • Journal of Electrical Engineering and Technology
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    • v.12 no.2
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    • pp.820-829
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    • 2017
  • Vegetable oil dielectrics have been used in transformers as green alternatives to mineral insulating oils for about twenty years, because of their advantages of non-toxic, biodegradability, and renewability. However, the viscosity of vegetable oils is more than 3 times of mineral oils, which means a poor heat dissipation capacity. To get low-viscosity dielectrics, transesterification and purification were performed to prepare vegetable oil methyl esters in this study. Electrical and physical properties were determined to investigate their potential as dielectrics. The results showed that the methyl ester products had good dielectric strengths, high water saturation and enough fire resistance. The viscosities (at $40^{\circ}C$) were 0.2 times less than FR3 fluid, and 0.7 times less than mineral oil, which indicated superior cooling capacity as we expected. With the assistance of 0.5 wt% pour point depressants, canola oil methyl ester exhibited the lowest pour point ($-26^{\circ}C$) among the products which was lower than FR3 fluid ($-21^{\circ}C$) and 25# mineral oil ($-23^{\circ}C$). Thus, canola oil methyl ester was the best candidate as a low-viscosity vegetable oil-based dielectric. The low-viscosity fluid could extend the service life of transformers by its better cooling capacity compared with nature ester dielectrics.

Influence of "Historical Effects" on the Rheological Properties of a Polyacrylonitrile Copolymer Solution

  • Cheng, Yumin;Zhang, Huibo;Zhang, Shuangkun;Liu, Weiwei;Wang, Jing;Cheng, Run;Ryu, SeungKon;Jin, Riguang
    • Carbon letters
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    • v.14 no.1
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    • pp.45-50
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    • 2013
  • Polyacrylonitrile (PAN) copolymers of different molecular weights were synthesized by a suspension polymerization and precipitation polymerization method. The rheology behaviors of the synthesized PAN copolymers were investigated in relation to their molecular weight, solid content and melting temperature. The influence of "historical effects" on the spinning solution of PAN was studied by analyzing the laws of viscosity considering the diversification time and temperature. The viscosity disciplines of each spinning solution conformed well to the rheological universal laws in a comparison of the suspension polymerization product with that of precipitation polymerization. Viscosity changes in the swelling process of dissolution were gentler in the suspension polymerization product; a small amount of water will quickly debase the solution viscosity, and high-speed mixing can greatly shorten the time required by the spinning solution to reach the final viscosity.

Development of Surface Acoustic Wave Sensor for Viscosity Measurement of Low Viscose Liquid Using Love Wave (Love파를 이용한 저점성 유체 점도 측정용 표면 탄성파 센서 개발)

  • Lee, Sang-Dae;Kim, Ki-Bok;Lee, Dae-Su
    • Journal of Biosystems Engineering
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    • v.33 no.4
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    • pp.282-287
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    • 2008
  • Love wave is one of the shear horizontal waves and it can propagate between two layers in liquid without energy loss. The SAW (surface acoustic wave) sensor using Love wave is very useful for real time measurement of the viscosity of liquid with high sensitivity. In this study, the 77 MHz and 155 MHz Love wave SAW sensors were fabricated and use to measure the viscosity of low viscous liquid. To generate the surface acoustic wave, the inter-digital transducers were fabricated on the quartz crystal wafer. In order to obtain the optimal thickness of the coating film (novolac photoresist) generating the Love wave on the surface of SAW device, theoretical calculation was performed. The performances of fabricated Love wave SAW sensors were tested. As test liquid, pure water and glycerol solutions having different concentrations were used. Since the determination coefficients of the regression equations for measuring the viscosity of liquid are greater than 0.98, the developed Love wave SAW sensors in this study will be very useful for precise measurement of viscosity of liquid.

Flow and Heat Transfer Analysis of Copper-water Nanofluid with Temperature Dependent Viscosity Past a Riga Plate

  • Ahmad, A.;Ahmed, S.;Abbasi, F.M.
    • Journal of Magnetics
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    • v.22 no.2
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    • pp.181-187
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    • 2017
  • Flow of electrically conducting nanofluids is of pivotal importance in countless industrial and medical appliances. Fluctuations in thermophysical properties of such fluids due to variations in temperature have not received due attention in the available literature. Present investigation aims to fill this void by analyzing the flow of copper-water nanofluid with temperature dependent viscosity past a Riga plate. Strong wall suction and viscous dissipation have also been taken into account. Numerical solutions for the resulting nonlinear system have been obtained. Results are presented in the graphical and tabular format in order to facilitate the physical analysis. An estimated expression for skin friction coefficient and Nusselt number are obtained by performing linear regression on numerical data for embedded parameters. Results indicate that the temperature dependent viscosity alters the velocity as well as the temperature of the nanofluid and is of considerable importance in the processes where high accuracy is desired. Addition of copper nanoparticles makes the momentum boundary layer thinner whereas viscosity parameter does not affect the boundary layer thickness. Moreover, the regression expressions indicate that magnitude of rate of change in effective skin friction coefficient and Nusselt number with respect to nanoparticles volume fraction is prominent when compared with the rate of change with variable viscosity parameter and modified Hartmann number.

Study on the Friction Characteristics of Advanced High Strength Steel Sheet (초고강도강판의 마찰특성에 관한 연구)

  • Kim, N.J.;Kim, S.H.;Jung, K.R.;Park, S.B.;Keum, Y.T.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.10a
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    • pp.250-253
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    • 2009
  • In this study, the friction test was performed to find friction characteristics of advanced high strength steel (AHSS) sheets and the multiple regression method was employed to obtain friction models. The friction coefficients associated with the lubricant viscosity, drawing speed, and blank holding pressure are measured. Differently from GA steel sheets, the effects of the lubricant viscosity and pulling speed are a little, which are explained by a theory of adhesion and wear as well as a deformation of friction surface. In addition, the effects of friction parameters are numerically represented by friction regression models.

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Studies on the Packing Characteristics of Coating Colors Based on the Rheological Properties at High Shear Rates (고전단점도 측정에 의한 도공액의 패킹 특성 연구)

  • 이학래;성용주
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.29 no.2
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    • pp.7-15
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    • 1997
  • High shear viscosity at several solids levels was measured for a number of pigment slurries and coating colors containing either anionic or amphoteric latex and analyzed according to Mooney and Eiler equations. Maximum packing fraction and intrinsic viscosity were obtained and compared. Eiler equation provides more credible information than Mooney equation on particle packing and intrinsic viscosity. The packing fraction obtained from Eiler equation was slightly greater than that obtained from static FCC measurement indicating the influence of pigment movement under the dynamic condition. Amphoteric latex caused 4-5% increase of maximum packing fraction of a coating color when its pH is lowered from 7 to 6, while anionic latex did not show any significant change in packing characteristics.

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