• Title, Summary, Keyword: fluid concentration

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Contribution of Bulk Flow to Transport Mechanisms of the Membranes Surrounding Amniotic Fluid in the Rabbit

  • Lim, Young-Cheol;Lee, Sang-Jin;Sung, Ho-Kyung
    • The Korean journal of physiology & pharmacology
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    • v.28 no.1
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    • pp.79-90
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    • 1994
  • The objective of the present study is to assess the contribution of bulk flow to the regulatory mechanism of amniotic fluid volume and its ionic concentration in the membranes surrounding the amniotic fluid. For quantitative assessment, we prepared 4 kinds of artificial amniotic fIuids (isotonic isovolumetric, hypotonic isovolumetric, isotonic hypervolumetric and hypotonic hypervolumetric ones) by replacing 70% of amniotic fluid of pregnant rabbits with water or normal Tyrode solutions. Isoosmotic saline of 0.5 ml volume containing 0.05% Censored and 15 mM/l LiCl was administered initially into amniotic sacs of all subject animals. Samples of amniotic fluid were collected in after 30 and 90 minute intervals; the concentrations of Censored, $Na^+\;and\;Li^+$ were determined and compared. Followings are the results obtained. 1. from isovolumetric and increased Congcord group, we couldn't find significant change in $Li^+\;and\;Na^+$ concentration in isotonic amniotic fluid. However, $Na^+$ concentration increased significantly as well as a striking increase in Censored concentration in hypotonic amniotic fluid. 2. In isovoIumetric and decreased Censored group, the rate of $[Li^+]$ decrement and the rate of $[Na^+]$ increment were much higher in hypotonic amniotic fluid than in isotonic. 3. In hypervolumetric and increased Censored group, the rate of $Na^+$ efflux increased proportionately with the increment of Censored concentration up to 0.98, which was higher than the rate of $Li^+$ efflux in isotonic amniotic fluid. However, the increment of $Na^+$ concentration was rather related with the initial $Na^+$ concentration in hypotonic amniotic fluid, showing inverse relationship. $Li^+$ concentration increased only when there was a marked increase in Censored concentration and approached near a maximum value or 1. 4. For hypervolumetric and decreased Censored group, the observations were identical to isovolumetric and decreased Censored group. From these results the following conclusions could be made: 1) There is no net movement of water or monovalent cations across the membranes surrounding amniotic fIuid in isotonic isovolumetric condition. In contrast, there is a net efflux of amniotic fluid by osmotic bulk flow, resulting in elevation of $Na^+$ concentration in hypotonic isovolumetric condition. 2) In hypervolumetric conditions, there is a massive efflux of amniotic fluid or solvent drag through the surrounding membranes by fiItrative bulk flow, where the rate of $Na^+$ efflux has a linear relationship with that of water efflux. This is assumed to be carried out through enlarged and newly opened intercellular spaces resulting from increased intraamniotic pressure. 3) Once increasing intraamniotic pressure reaches a point allowing $Li^+$ to pass through during osmotic bulk flow in hypotonic amniotic fIuid, $Na^+$ influx seems to occur by diffusion simultaneously or immediately thereafter, too.

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Enhanced vertical diffusion coefficient at upper layer of suspended sediment concentration profile

  • Kim, Hyoseob;Jang, Changhwan;Lhm, Namjae
    • Ocean Systems Engineering
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    • v.2 no.4
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    • pp.289-295
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    • 2012
  • Assume fluid eddy viscosity in the vertical direction is parabolic. Sediment particles diffuse with the given fluid eddy viscosity. However, when the vertical diffusion coefficient profile is computed from the suspended sediment concentration profile, the coefficient shows lager values than the fluid mixing coefficient values. This trend was explained by using two sizes of sediment particles. When fine sediment particles like wash load are added in water column the sediment mixing coefficient looks much larger than the fluid mixing coefficient.

An experimental study on the reattachment of Non-Newtonian fluid flows in a sudden expansion pipe (돌연 확대관에서 비뉴우튼 유체의 재접착 실험)

  • 전운학;이행남
    • Journal of the korean Society of Automotive Engineers
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    • v.15 no.1
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    • pp.45-54
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    • 1993
  • The reattachment lengths of the Non-Newtonian fluid are investigated in the sudden expansion pipes whose ratios are 2.316 and 3.368, and the range of the Reynolds numbers is 100-30000. The reattachment lengths for the viscoelastic fluid in the laminar flow region are found to be much shorter than those of the Newtonian fluid, and decrease significantly with the increase of the concentration of viscoelastic fluid is two or three times longer than those of water, and gradually increases with the increase of the concentration of viscoelastic fluid.

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FLUID-GRANULE MIXED FLOIW DOWNSTREAM OF SCOUR HOLE AT OUTLET OF HYDRAULIC STRUCTURE

  • Kim, Jin-Hong;Shim, Myung-Pil;Kim, Kyung-Sub
    • Water Engineering Research
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    • v.3 no.3
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    • pp.155-162
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    • 2002
  • This study presents the theoretical approach for volume concentration, velocity profile, and granular discharge on the fluid-granule mixed flow downstream of the scour hole at the outlet of the hydraulic structure. Concept of dilatant model was applied for the stress-strain relationships of fluid-granule mixed flow since the flow downstream of the scour hole corresponds to debris flow, where momentum transfers through particle collisions. Mathematical formulations were derived using momentum equation and stress-strain relation of the fluid-granule mixture. Velocity profile under the assumption of uniform concentration over flowing layer showed the downward convex type. Deposition angle of downstream hump was found to be a function of an upstream slope angle, a dynamic friction angle and a volume concentration irrespective of flow itself, Granular discharge and the overflow depth were obtained with given values of inflow rates. Experimental results showed relatively good agreements with theoretical ones.

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Fluid Sensor and Algorithm for Trouble Detection of Solar Thermal System (태양열 시스템 고장진단을 위한 유체센서와 알고리즘)

  • Lee, Won-Chul;Hong, Hiki
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.8
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    • pp.351-356
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    • 2014
  • Typical trouble patterns in solar thermal systems include working fluid leakage and freezing other than breakdown of pump. A fluid sensor for measuring electric resistance of fluid was developed and installed at the top of the collector piping in order to check the fault of solar system. Working fluid level in the pipe was determined by measuring electric resistance from a fluid sensor. On the base of this, it was confirmed that the fluid sensor diagnoses leakage of fluid. Electric resistance of propylene glycol aqueous solution was measured in the range of $0{\sim}70^{\circ}C$ and 0~40% of concentration. The response surface analysis was performed by using a central composite design, and the regression equation was derived from the relationship between electric resistance, temperature, and concentration. Through the experiment in a real solar system, we can estimate a concentration of working fluid when a pump is not operating and predict a possibility of freezing. Finally, an effective algorithm for trouble shooting was proposed to operate and maintain the solar system.

Study on the Crevice Corrosion of Mild Steel in Fluid Environment (유체환경 중에서 연강재의 간극부식에 관한 연구)

  • Lim, Uh Job;Yun, Byoung Du
    • 유체기계공업학회:학술대회논문집
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    • pp.373-378
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    • 2000
  • The crevice corrosion of local corrosion occur when the gap exist on metal surface. This crevice corrosion happen to region such as flange of pipe, contact part of casing, under gasket and packing, between valve disk and seat of pump etc. Especially The crevice corrosion of mild steel(SS 400) get serious. This paper was studied on the crevice corrosion of SS 400 in fluid environment. In $0\%,\;2\%,\;3.5\%,\;5\% NaCl$ solution, the aspect of the crevice corrosion and polarization behavior under the crevice corrosion was investigated. And Weight loss rate of SS 400 with crevice and non-crevice was measured according to the NaCl concentration. The main results obtained are as follows : 1) Under crevice corrosion, the corrosion potential become less noble as the concentration of NaCl solution increased. 2) The current density under open circuit potential was high drained as concentration of NaCl solution increased by $3.5\%$ but the concentration increased over $3.5\%$, the current density was low drained. 3) The weight loss rate of SS 400 was increased as concentration of NaCl solution Increased by $3.5\%$, but the concentration increased over $3.5\%$, that of SS 400 was decreased. 4) Effect of oxygen for crevice corrosion in the concentration of $3.5\%$ NaCl solution become sensitive than that $0\%$ NaCl solution.

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Effect of Changing Amniotic Fluid Osmolarity on the $Li^+$ Transport Through the Membrane Surrounding Amniotic Fluid in the Rabbit

  • Chang, Jin-Keun;Lee, Sang-Jin;Sung, Ho-Kyung
    • The Korean journal of physiology & pharmacology
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    • v.27 no.1
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    • pp.13-25
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    • 1993
  • To study the regulation of amniotic fluid volume and electrolyte concentration by the Membranes surrounding the amniotic fluid, the rate of $Li^+$ disappearance from amniotic sac of expired fetuses were examined while increasing the amniotic volume and osmolarity in rabbits. After intraamniotic injection of 1 ml isosmotic saline (about 20% of the amniotic fluid volume) containing 15 mM LiCl and 0.5 g/L Censored, the time courses of $Li^+$ and Censored disappearance were determined. From there the $Li^+$ clearance through the extrafetal routes was estimated and compared with that obtained from living fetuses. The volume, $Na^+$ concentration and osmolarity of amniotic fluid were measured and their relationships with $Li^+$ disappearance were evaluated. The fellowing results were obtained: 1. The rate of disappearance from amniotic fluid of living fetuses during the first 30 minutes was strikingly higher for $Li^+$ than for Censored, suggesting that extrafetal routes exist. At 60 and 90 minutes, however, the disappearance rate of $Li^+$ was less than that of Censored, suggesting the possibility of $Li^+$ reentry through fetal urination. 2. The disappearance of $Li^+$ from the amniotic fluid of the expired fetus was substantial, although lower than that of living fetuses, throughout the experimental period. 3. The $Na^+$ concentration and the osmolarity of the amniotic fluid of expired fetus measured 30 minutes after an intraamniotic injection of isoosmotic saline showed wide variation, but thereafter they changed gradually towards the normal extracellular fluid level. 4. When the amniotic fluid was iso- or hyposmolar, the rate of $Li^+$ disappearance from the amniotic fluid of the expired fetuses showed little variation. However, when the amniotic fluid was hyperosmolar, the rate at 30 minutes was markedly lower than those of isosmotic or hyposmotic amniotic fluid. At 90 minutes, the rate of $Li^+$ disappearance in hyperosmolar fluid reached a similar level to the rate in isosmolar fluid. 5. The intraamniotic injection of 400 mOsm/L saline solution decreased the disappearance rate of $Li^+$ from expired fetuses, while the injection of mannitol into the maternal vein induced no significant change. From these results it is concluded that: 1) a significant amount of $Li^+$ may leave the amniotic fluid via filtration through the membranes surrounding the amniotic fluid, 2) during hyperosmolar challenge to amniotic fluid, osmotic bulk flow might counteract the filterable loss, and 3) $Li^+$ disappearance might continue even after the volume and osmolarity of the amniotic fluid have recovered to control values.

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Atomization of Shear-Thinning Liquid Slurry Discharging from Fan Spray Nozzles (고형성분이 포함된 전단희석 유체의 선형(扇形) 분무노즐을 통한 미립화)

  • An, S.M.;Ryu, S.U.;Lee, S.Y.
    • Journal of ILASS-Korea
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    • v.13 no.1
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    • pp.42-50
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    • 2008
  • In the present work, atomization characteristics of shear-thinning liquid slurry discharging from fan spray nozzles were studied experimentally for spray painting applications. The effects of solid particle size and concentration on the properties (especially on the viscosity) of suspensions and mean drop size were examined by using model fluids. In the range of low particle concentration (below 3 wt%), the fluid viscosity was primarily determined by the particle size. On the other hand, in the range of high particle concentration (higher than 10 wt%), the agglomeration phenomenon and the oil absorption capability of solid particles played major roles in determining the fluid viscosity. In the high concentration region, which most of the paints belong to, the fluid became more viscous and the shear thinning behavior appeared more prominent as the particle concentration was increased. In this region, mean drop size(SMD) decreased more rapidly with the increase of the injection pressure. Also, SMD became larger with the higher particle concentration and the larger particle size.

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Effects of the Concentration and the Temperature on the Thermophysical Properties of Purely-Viscous Non-Newtonian Fluid (순수점성 비뉴톤유체의 물성치들에 대한 농도 및 온도의 영향)

  • 조금남
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.3
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    • pp.670-680
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    • 1994
  • The thermophysical properties of Non-Newtonian fluid as the function of the temperature and the concentration are needed in many rheological heat transfer and fluid mechanics problems. The present work investigated the effects of the concentration and the temperature on the thermophysical properties of purely-viscous Non-Newtonian fluids such as the isobaric thermal expansion coefficient, density, zero-shear-rate viscosity, and zero-shear-rate dynamic viscosity within the experimental temperature range from $25^{\circ}C$ to $55^{\circ}C$. The densities of the test fluids were determined as the function of the temperature by utilizing a reference density and the least square equation for the measured isobaric thermal expansion coefficient. As the concentration of purely-viscous Non-Newtonian fluid was increased up to 10,000 wppm, the densities were proportionally increased up to 0.4%. The zero-shear-rate viscosities of test fluids were measured before and after the measurements of the first thermal expansion coefficients and the densities of Non-Newtonian fluid. Even though they were changed up to approximately 22% due to thermal aging and cycling, they had no effects on the thermal expansion coefficients and the densities of Non-Newtonian fluid. The zero-shear-rate dynamic viscosities for purely-viscous Non-Newtonian fluids were compared with the values for distilled water. They showed the similar trend with the zero-shear-rate viscosities due to small differences in the densities for both distilled water and purely-viscous Non-Newtonian fluid.

The Ratio of Testosteron and Follicle Stimulating Hormone in the Amniotic Fluid (양수내(羊水內)의 Testosteron대(對) Follicle Stimulating Hormone 비율(比率)에 관(關)한 연구(硏究))

  • Cho, Suk-Shin
    • The Korean Journal of Nuclear Medicine
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    • v.16 no.2
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    • pp.37-47
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    • 1982
  • To evaluate fetal sex-hormonal status before delivery, testosterone and follicle stimulating normone(FSH) levels were measured in 64 amniotic fluid samples at midgestation by radioimmunoassay method. The mean concentration of testosterone in amniotic fluid of 37 cases carrying male fetus was 90.7 pg/ml and 27 cases carrying female fetus was 62.3 pg/ml. The mean :amniotic fluid FSH concentration of male fetus was 1.15 mIU/ml and of female fetus was 11.98 mIU/ml. The amniotic fluid testoserone and FSH concentrations had statistical difference between male and female fetuses. The ratio of testosterone over FSH in the amniotic fluid was 231.2 in male, 9.8 in female respectively and very significant difference was noticed. The levels of testosterone/FSH greater than 25 were found over 92% of male fetus and lesser than 25 were found over 92% female fetus. Measurement of testosterone and FSH especially testosterone/FSH ratio in amniotic fluid in midgestation may be an adjunct to other method of fetal sex determination.

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