• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1999년도 춘계 학술대회논문집
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• pp.192-198
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• 1999

The present study proposes modified temperature-dependent non-Newtonian viscosity model and investigates flow characters and heat transfer enhancement of the viscoelastic non-Newtonian fluid in a 2:1 rectangular duct. The proposed modified temperature dependent viscosity model has non-zero value near the high temperature and high shear rate region while on the existing viscosity models have zero value. Two versions of thermal boundary conditions involving difference combination of heated walls and adiabatic walls are analyzed in this study. The combined effect of temperature dependent viscosity, buoyancy, and secondary flow caused by second normal stress difference are ail considered. The Reiner-Rivlin model is adopted as a viscoelastic fluid model to simulate the secondary flow caused by second normal stress difference. Calculated Nusselt numbers by the modified temperature-dependent viscosity model gives under prediction than the existing temperature-dependent viscosity model in the regions of thermally developed with same secondary normal stress difference coefficients with experimental results in the regions of thermally developed. The heat transfer enhancement of the viscoelastic fluid in a 2:1 rectangular duct is highly dependent on the secondary flow caused by the magnitude of second normal stress difference.

• Journal of Nutrition and Health
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• 제29권6호
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• pp.615-621
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• 1996

Experiments were carried out in humans to assess the relationship between viscosity and post-prandial glucose response of soluble fibers. Eight(3 male and 5 female) healthy individuals were tested for their glucose response after taking control meals or 3 test fiber meals of different viscosities. Meal viscosity of the test food was adjusted to be between 200 and 70, 000 cps. There was a significant increase in post-prandial glucose response(p=0.01) in control meals by solely increasing the volume of water. Fiber with the highest viscosity konjac mannan demonstrated the lowest relative glucose response(70.1$\pm$6.6), followed by medium viscosity xanthan (79.3$\pm$8.7)and low viscosity psyllium (86.3$\pm$10.5). The difference is significant at the level of p<0.05. However, no significant difference in relative glucose response of the same fiber was found when the 4 levels of water were added to make different meal viscosity of each fiber (p=0.476). This result suggested that hypoglycemic action of soluble dietary fibers is related to fiber viscosity rather than meal viscosity.

• Journal of Mechanical Science and Technology
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• 제20권3호
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• pp.382-390
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• 2006

The present study proposes a modified temperature-dependent non-Newtonian viscosity model and investigates the flow characteristics and heat transfer enhancement of the viscoelastic non-Newtonian fluid in a 2:1 rectangular duct. The combined effects of temperature dependent viscosity, buoyancy, and secondary flow caused by the second normal stress difference are considered. Calculated Nusselt numbers by the modified temperature-dependent viscosity model give good agreement with the experimental results. The heat transfer enhancement of viscoelastic fluid in a rectangular duct is highly dependent on the secondary flow caused by the magnitude of second normal stress difference.

• 센서학회지
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• 제17권4호
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• pp.289-294
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• 2008

The purpose of this study is to materialize the viscosity sensor by using the SH-SAW sensor of which the center frequency is operated at higher than 50 MHz. In order to measure the viscosity, SAW sensor of which the center frequency is operated at 100 MHz is developed. By using the developed sensor, phase shift, delay time, insertion loss, and frequency variation are measured at different viscosity. The result shows that the phase shift difference between the viscosity variations is such that the difference between the distilled water and the 100 % glycerol solution is approximately $45^{\circ}$, the change of the insertion loss is approximately 9 dB, and the difference of frequency variation is approximately 5.9 MHz. Therefore, it is shown that viscosity of unknown solution can be measured with the surface acoustic wave sensor.

• Journal of Oral Medicine and Pain
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• 제17권2호
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• pp.87-97
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• 1992

The purpose of this study is to investigate the age-and sex-related changes in the pH of resting saliva, viscosity, microorganisms and immunoglobulin A of stimulated whole saliva, and to investigate their correlations. The 120 healthy subjects were included in this study and the author used cone-and plate digital viscometer for viscosity, MSB agar for Streptococcus mutans, SL Rogosa agar for lactobacilli, and single radial immunodiffusion technique for immunoglobulinA. The obtained results were as follows : 1. There was no significant difference in pH, viscosity, Streptococcus mutans lactobacilli and immunoglobulin A of the saliva between males and females. 2. The viscosity values of stimulated whole saliva showed the increasing pattern with aging. 3. DMFS (or dmfs) rate was not correlated with pH, viscosity, Streptococcus mutans, lactobacilli and immunoglobulin A of the saliva. 4. There was a significant difference in the concentration of immunoglobulin A between the group under 10 and groups above 10. 5. The viscosity values of stimulated whole saliva showed the increasing pattern with decreasing of the number of Streptococcus mutans.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1752-1757
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• 2008

Simple and highly efficient droplet merging method is proposed, which enables two nanoliter or picoliter droplets to merge regularly in a straight microchannel. We observe that two droplets of the same size but of different viscosities are merged by velocity difference induced as they are transported with the carrier fluid. To make viscosity difference, the mass ratio of water and glycerol is varied. Two droplets of the same size or of different sizes are generated alternatingly in the cross channel by controlling flowrates. This droplet merging method can be used to mix or encapsulate one target sample with another material, so that it can be applied to cell lysis, particle synthesis, drug discovery, hydrogel-bead production, and so on.

• KSBB Journal
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• 제5권4호
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• pp.403-410
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• 1990

Application of the Rheocatch Hotwire Monitoring System for food biotechnology process was evaluated. The growth of microogranism, E coli (JM 83 and Sigma) and Corynesccfertun glutamicum, were monitored. in the fermentor. The cell growth could not be detected the temperature differences between the hotwire and samples($\Delta$T) as indicated by the monitoring system during the fermentation processes. The cell concentration of less than 2g/dl was not sufficient to generate the measurable temperature difference in the fermentor. In order to calibrate the Rheocatch Monitoring System, the temperature difference as a function of solute concentration (microbial cells, sodium cholide, sucrose and dextran) was studied. The relationship between $\Delta$T and the concentration of microbial cells, sucrose and dextran can be expressed in a power series. Further studied with dextran indicated that viscosity and/or kinematic viscosity increase exponentially with an increase in $\Delta$T This is regardless of the concentration and molecular weight of dextran. $\Delta$T linearly increases with the logarithm of molecular weight, while the logarithm of viscosity and the logarithm of kinematic viscosity increase with the logarithm of molecular weight.

• Journal of Biosystems Engineering
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• 제37권6호
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• pp.429-433
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• 2012

Purpose: While rapeseed oil, soy bean oil, palm oil and waste cooking oil are being used for biodiesel, the viscosity of them should be lowered for fuel. The most widely used method of decreasing the viscosity of vegetable oil is to convert the vegetable oil into fatty acid methyl ester but is too expensive. This experiment uses ultrasonic energy, instead of converting the vegetable oil into fatty acid methyl ester, to lower the viscosity of the waste cooking oil. Methods: For irradiation treatment, the sample in a beaker was irradiated with ultrasonic energy and the viscosity and temperature were measured with a viscometer. For heating treatment, the sample in a beaker was heated and the viscosity and temperature were measured with a viscometer. Kinematic viscosity was calculated by dividing absolute viscosity with density. Results: The kinematic viscosity of waste cooking oil and cooking oil are up to ten times as high as that of light oil at room temperature. However, the difference of two types of oil decreased by four times as the temperature increased over $83^{\circ}C$. When the viscosity by the treatment of ultrasonic energy irradiation was compared to one by the heating treatment to the waste cooking oil, the viscosity by the treatment of ultrasonic energy irradiation was lower by maximum of 22% and minimum of 12%, than one by the heating treatment. Conclusions: Ultrasonic energy irradiation lowered the viscosity more than the heating treatment did, and ultrasonic energy irradiation has an enormous effect on fuel reforming.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제30권2호
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• pp.81-84
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• 2004

It is well known that malignant tumor have hypoxic cell fraction, which is radio resistant and is one of the most important cause of local recurrence after radiotherapy. One of the causes of hypoxia in tumor is blood flow decrease due to increase in blood flow resistance and one of the causes of increased blood flow resistance could be attributed to the increase in blood viscosity. For the evaluation of the change of blood viscosity in oral cancer, experiments were carried out to test the change of blood viscosity among the normal control and xenografted oral cancer nude mice. Relative viscosity measured against distilled water was $3.30{\pm}0.14$ for normal control, and $3.67{\pm}0.62$ for tumor bearing mice at the first time of blood sampling in experimental period ($100mm^3$ $200mm^3$). There was no statistically significant difference between the control group and experimental group (p>0.05). However, as the tumor grew, significant difference of blood viscosity was detected at the third time of blood sampling (control group:$3.37{\pm}0.59$, and experimental group: $4.31{\pm}0.41\;300mm^3$

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제30권3호
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• pp.181-185
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• 2004

Malignant tumor have hypoxic cell fraction, which makes radio-resistant and hypoxia in tumor is a result from the blood flow decrease caused by increase in blood flow resistance. Blood viscosity increase is major factor of increased blood flow resistance and it could be attributed to the decrease in blood deformability index. For the evaluation of the change of blood viscosity and blood deformability in oral squamous cell carcinoma, we perform the test of the change of those factors between the normal control group and oral squamous cell carcinoma cell patient group. Relative viscosity measured against distilled water was $5.25{\pm}0.14$ for normal control group, and $5.78{\pm}0.26$ for the SCC patient group and there was statistical significance between the groups. However, there was no significant difference between the groups in blood viscosity between the groups by tumor size (T1+T2 vs T3+T4). Also, there was no significant difference between the normal control group and SCC patient group in blood deformability index and between the groups by tumor size (T1+T2 vs T3+T4). Increase in blood viscosity was confirmed with this study and it can be postulated that modification blood viscosity might contribute to decrease of hypoxia fraction in oral squamous cell carcinoma, thus improve the effect of radiotherapy and it can be assumed that the main factor of blood viscosity increase is not decrease of blood deformability in oral squamous cell carcinoma.