• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.75-79
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• 1989

The rheological properties of sugar and cocoa particle suspensions in cocoa butter under molten condition were analyzed with Haake rotationary viscometer. Both suspensions had yield value and showed rheopexy at low shear rate and thixotropy at high shear rate. Flow behaviors of the suspensions were analyzed with modified Casson model. Casson viscosity and yield value increased with increasing the concentration of sugar and cocoa particles. There was an obvious dependence of the Casson viscosity and yield value on the particle size distributions that was represented by the Sauter mean diameter of the particles. Casson viscosity and yield value of cocoa butter-sugar suspension increased with increasing the fineness of sugar particle crystal. With increasing the fineness of cocoa particle a decreasing Casson viscosity of cocoa butter-cocoa particle suspension was achieved, but the yield value did not change significantly with cocoa particle size. Therefore, it was predicted that the best rheological properties of chocolate could be obtained with the combination of coarse ground sugar $(d=36.30{\mu}m)$ and fine ground cocoa particle $(d=14.81{\mu}m)$ within the studied range.

• Food Science and Biotechnology
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• v.15 no.1
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• pp.33-38
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• 2006

This study was performed to provide basic rheological data of dandelion root concentrates in order to predict their processing aptitude and usefulness as functional foods material. The hot water and 70% ethanol extracts of dandelion root were concentrated at 5, 20, and 50 Brix, and their static viscosity, dynamic viscosity, and Arrhenius plots were investigated. Almost all hot water concentrates showed the typical flow properties of a pseudoplastic fluid, but evaluation using the power law model indicated that the 70% ethanol concentrates showed a flow behavior close to a Newtonian fluid. The apparent viscosity of hot water and 70% ethanol concentrates decreased with increasing temperature. Yield stresses of hot water and 70% ethanol concentrates by Herschel-Bulkley model application were in the range of 0.026 - 1.368 Pa and 0.022 - 0.238 Pa, respectively. The effect of temperature and concentration on the apparent viscosity was examined by Arrhenius equation. The activation energies of hot water and 70% ethanol concentrates were in the range of $8.762-23.778{\times}10^3\;J/mol{\cdot}kg$ and $3.217-20.384{\times}10^3\;J/mol{\cdot}kg$ with increasing concentration, respectively. Storage (G') and loss (G") moduli were generally increased with increasing frequency. For the 70% ethanol concentrates, G" predominated over G' at all applied frequencies and so they showed the typical flow behavior of a low molecular solution. However, for the hot water concentrates, G' predominated over G" at more than 1.9 rad/sec (cross-over point) and so they showed the typical flow behavior of a macromolecular solution.

• Journal of the Korean Solar Energy Society
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• v.32 no.4
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• pp.9-16
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• 2012

Nanofluids using Carbon Nanotubes have a excellent thermal characteristic. In this study, for increasing the efficiency of solar collector, the thermal conductivity and viscosity of Ethanol-Oxidized Multi-walled Carbon Nanofluids were measured. Nanofluids were manufactured by ultra-sonic dispersing Oxidized Multi-walled Carbon Nanotubes(OMWCNTs) in ethanol at the rates of 0.0005 ~ 0.1 vol%. The thermal conductivity and viscosity of manufactured nanofluids were measured at the low temperature($10^{\circ}C$), the room temperature($25^{\circ}C$) and the high temperature($70^{\circ}C$). For measuring thermal conductivity and viscosity, we used transient hot-wire method and rotational digital viscometer, respectively. As a result, under given temperature conditions, thermal conductivity of the 0.1 vol% nanofluids improved 33.74% ($10^{\circ}C$), 33.14% ($25^{\circ}C$) and 32.36% ($70^{\circ}C$), and its viscosity increased by 37.93% ($10^{\circ}C$), 31.92% ($25^{\circ}C$) and 29.42% ($70^{\circ}C$) than the base fluids.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.6
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• pp.483-489
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• 2019

For machine learning techniques, a large amount of high-quality material property data should be accumulated. In this study, several data for an alumina tape casting process were produced with the variables of slurry viscosity, gap size, and coating speed. The alumina tapes were manufactured in the range of 1,000~6,000 cps for slurry viscosity, $300{\sim}1,000{\mu}m$ for gap size, and 0.5~2.0 m/min for coating speed. As a result, the lower the viscosity, coating speed, and gap size, the more pore-free tapes could be manufactured. The viscosity of the slurry limited the minimum thickness of the tape. Green sheets with high packing density were manufactured from the slurry of 100~6,000 cps slurry viscosity, coating speed of 0.5 m/min, and a $300{\sim}500{\mu}m$ gap size.

• Journal of Korea Foresty Energy
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• v.23 no.1
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• pp.38-44
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• 2004

The application of the dispersant is indispensable to the manufacture of Korean traditional paper (Hanji). However the mucilage of which extracted from Abelmoschus manihot root has viscosity drop problem in summertime and synthetic dispersant such as polyacrylamide (PAM) and polyethyleneoxide (PEO) have some problems that under the influence of the quality of. water, cohesion, and bad solubility. This study was carried out not only to develop new natural dispersant that can solve such problems but also to investigate the viscosity and papermaking characteristics of Hydrangea paniculata mucilage. There were no viscosity changes between control and treated mucilage that adjusted to pH 9, heated 6 hours at 40 $^{\circ}C$, and stored heating treatment one for a week at 5 $^{\circ}C$. The treatment of mucilage that adjusted to pH 9 and aged for 120 hours at 4$0^{\circ}C$ resulted in viscosity drop. In the hydrolysis of mucilage, galacturonic acid and glucuronic acid contents were decreased by heating and pH adjusting treatments. Wet web stripping quality and physical properties of Korean traditional paper, which used Hydrangea paniculatamucilage were same or superior to the Abelmoschus manihot root.

• Polymer(Korea)
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• v.26 no.5
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• pp.607-614
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• 2002

Polyorganosiloxane(HBPS) modified polyurethane (UMPS) was synthesized to improve weatherability in the polyurethane (ITPU) sealant and its rheological propoerty was investigated. It was found that the viscosity increased with increasing HBPS content in polyurethane and maximum viscosity was observed in UMPS having 70/30 ITPU/HBPS ratio. This was understood that the segregation of HBPS segment in UMPS chain has been developed. Further increasing of the content of HBPS resulted in the lowering of viscosity because of the flexibility of HBPS block segment in UMPS chain. It was also found that UMPS has more sensitive environmental dependency of viscosity than ITPU such as shear rate, humidity and temperature. In additions, UMPS having Si(O$CH_3$)$_3$ end group (TUMPS) by adding coupling agent up to 0.3 wt% resulted in the increase of viscosity by the acceleration of curing. But introducing more than 0.5wt% curing agent to TUMPS caused the lowering of viscosity because of less NCO group in TUMPS for the curing.

• Korean journal of food and cookery science
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• v.32 no.3
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• pp.253-260
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• 2016

Purpose: To develop fat-free dressing containing a resistant starch (RS) as a dietary fiber, the viscosity and stability of various type RSes prepared from wheat, maize, potato, rice, waxy rice, and amaranth starches were investigated by using Brookfield viscometer. The shape of RS granule in the dressing during storage was also observed. Methods: The viscosity of fat free dressing with different retrograded RS3 (RS3V) prepared from waxy rice starch with 0.1% lemon vinegar and ascorbate mixed solution had higher RS3 that was maintained constant during storage. Annealing and heating prior to cross-linking, and heating after cross-linking increased RS level of RS4 type starches. Results: The viscosities and stabilities of dressings with RS were different depending on starch sources and RS preparation conditions. The heated RS4 (HRS4) increased in viscosity and stability with RS4 addition. Especially the fat-free dressings with HRS4 prepared from rice and waxy rice starches maintained stability regardless of separation after one month storage with only 7% separation after 6 month storages. The shape of RS4 granule in acidic medium of dressing did not change until 6 months. Conclusion: In this study, RS4 made by the rice and waxy rice starches showed high viscosity and maintained stability of the fat-free dressings during storage.

• Journal of the Korean Wood Science and Technology
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• v.18 no.2
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• pp.25-35
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• 1990

To investigate the effects of swelling treatment by ammonia on characteristics of carboxymethy1cellulose(CMC) and CMC solution, the domestic kraft pulp pretreated with 5%, 10%, 15% and 20% $NH_4OH$ solution, was carboxymethylated by the standard method, and then the CMC prepared was tested. The physical properties of CMC and CMC solution, such as degree of substitution, transparency. viscosity, weight increase and solubility, were measured, and the comparison with commercial domestic CMC used as a food additive was done. The results obtained were as follows; 1. In CMC manufactured by standard solvent method, hardwood bleached kraft pulp(LBKP) was more substituted than safwood bleached kraft pulp(NBKP), and viscosity of NBKP was higher than that of LBKP. 2. When ammonia swelling treatment was done, degree of substitution gradually decreased with increasing concentration of $NH_4OH$, and degree of substitution of LBKP decreased with a larger range than that of NBKP. 3. When ammonia swelling treatment was done. transparency of CMC solution from LBKP was hardly effected, but in case of NBKP gradually increased with increasing concentration of $NH_4OH$. 4. When ammonia swelling treatment was done, viscosity of CMC solution was higher than that of CMC solution without ammonia swelling treatment. Especially, CMC of high viscosity could be manufactured in 5%, 10% concentration levels of $NH_4OH$. 5. In CMC manufactured from domestic NBKP, CMC at the range of 0.40 to 0.50 in DS was dispersed easily and quickly dissolved, and CMC at more than 0.50 in DS was dispersed slowly in water solution. 6. In comparison with commercial domestic CMC used as a food additive, CMC manufactured from domestic NBKP was higher in DS, and was lower in viscosity and transparency.

• Korean journal of food and cookery science
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• v.24 no.6
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• pp.882-890
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• 2008

The present study investigated the influence of different volumes of red hot pepper juice on the quality characteristics of fresh Pasta noodle. Supplementation with 0% (control), 2.5%, 5%, 7.5%, or 10% red hot pepper juice produced similar gelatinization characteristics of peak viscosity, temperature at peak viscosity, hot paste viscosity and numerical value of breakdown. However, increasing concentrations of red hot pepper juice produced progressively and significantly low cold paste viscosity and setback. The chromaticity of wet and cooked noodles was significantly lower in L value and significantly higher in +a and +b values with increasing volumes of red hot pepper juice. The texture of fresh noodles displayed no significant differences in hardness, adhesiveness and chewiness. The springiness and cohesiveness were lower and higher with the increase of added red hot pepper juice, respectively, but the differences just attained significance. For cooked noodles, adhesiveness, springiness, cohesiveness and chewiness tended to be higher with increasing volumes of red hot pepper juice, but again the differences just attained significance. Cooking characteristics of weight, volume, moisture absorptive power and turbidity decreased with increasing volumes of red hot pepper juice. Sensory characteristics of acceptability including appearance, color, flavor, taste, texture and overall-acceptability improved with increasing red hot pepper juice volume, in particular with 5% and 7.5%. Amylograph characteristics for initial paste temperature positively correlated with the texture characteristics for chewiness (p<0.05). Negatively correlated amylograph parameters included texture for springiness with for peak viscosity (p<0.01), texture for adhesiveness with hot paste viscosity (p<0.01) and breakdown with texture for adhesiveness, cohesiveness and chewiness (p<0.05).

• Elastomers and Composites
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• v.45 no.2
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• pp.122-128
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• 2010

We measured shear viscosity of copoly(styrene(St)/butyl methacrylate(BMA)) (co-PSB) particles, with a capillary rheometer at $170^{\circ}C$, prepared by suspension polymerization with hydrophobic silica as a stabilizer. co-PSB particles with the weight average molecular weights of lower than 74,800 g/mol displayed a Newtonian behavior at low shear rates. With the weight average molecular weight exceeding 136,800 g/mol, co-PSB particles showed shear thinning against shear rates and the absolute value of the slopes between shear viscosity vs. shear rate increased. When the ratio between St and BMA changed from 7/3 to 5/5 to 3/7, shear viscosity and glass transition decreased despite similar molecular weights. When the ratio was 1/9, it showed a large increase in initial shear viscosity despite reduced glass transition. Shear viscosity exhibited an increase in proportion to carbon black concentration. The effect of carbon black concentration on the shear viscosity of co-PSB composites was less pronounced compared to varying molecular weights and/or compositional ratio.