• Food Science and Biotechnology
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• v.17 no.2
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• pp.417-420
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• 2008

Rheological properties of sweet potato starch (SPS)-glucose composites (5%, w/w) at different concentrations (0, 10, 20, and 30%, w/w) of glucose were investigated in steady and dynamic shear. The steady shear rheological properties of SPS-glucose composites were determined from rheological parameters for power law and Casson flow models. At $25^{\circ}C$ all the samples showed a pronounced shear-thinning behaviors (n=0.29-0.37) with high Casson yield stress. In general, the presence of glucose resulted in the decrease in consistence index (K), apparent viscosity (${\eta}_{a,100}$), and yield stress (${\sigma}_{oc}$). Storage (G') and loss (G") moduli increased with an increase in frequency ($\omega$), while complex viscosity (${\eta}*$) decreased. Dynamic moduli (G', G", and ${\eta}*$) of the SPS-glucose composites at higher glucose concentrations (20 and 30%) were higher than those of the control (0% glucose) and also increased with increasing glucose concentration from 10 to 30%. The effect of glucose on steady and dynamic shear rheological properties of the SPS pastes appears to greatly depend on glucose concentration in the range of 10-30%.

• Culinary science and hospitality research
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• v.12 no.2 s.29
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• pp.168-183
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• 2006

The purpose of this study was to investigate quality characteristics of roll bread with the addition of Chungkukjang powder(0, 5, 10, 15, 20%). The antioxidative activity of antioxidative substances produced from several bacterial strains isolated from fermented foods were tested by DPPH $(\alpha,\alpha’-diphenyl-\beta-picrylhydrazyl)$ free radical scavenging activity. The most optimal medium condition for the production of antioxidative substance from Bacillus sp. FF-7 was 2% galactose as carbon source and 1% tryptone as nitrogen source. In color values, with increasing Chungkukjang powder content, the "lightness" (p<0.05) decreased in the crumb bread, while the redness(p<0.05) and yellowness(p<0.05) increased. The volume and specific volume of roll bread with 5.0% Chungkukjang powder were the highest(p<0.05). In the rheology measurements for the roll bread, the hardness (p<0.05) decreased with the addition of 5.0% Chungkukjang powder, but then increased with further additions of Chungkukjang up to 10.0%. Highest sensory scores for color, flavor, taste(p<0.05), texture(p<0.05) and overall acceptance(p<0.05) were obtained from roll bread with 5.0% Chungkukjang powder and control. From the results of this study, it was assumed that the development of food products using Chungkukjang is prospective in response to health-oriented consumers.

• Food Science and Biotechnology
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• v.16 no.5
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• pp.817-821
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• 2007

The effect of acetylated rice (AR) starch at different concentrations (0, 4, 6, and 8%) on rheological properties of surimi sols and gels was studied. Dynamic frequency sweeps of surimi-AR starch sols at $10^{\circ}C$ showed that the magnitudes of storage moduli (G') decreased with an increase in starch concentration while those of tan ${\delta}$ increased, indicating that the effect of AR starch on the viscoelastic properties of surimi sols depended on starch concentration. In general, the G' thermograms of surimi sols showed the similar sol-gel transition pattern and they were also influenced by the addition of AR starch. The presence of AR starch in the surimi gel system reduced the gel strength and expressible moisture content (EMC). Surimi-AR starch gels showed better freeze-thaw stability compared to the control (0% starch concentration). The effect of AR starch on the rheological properties of surimi sols and gels appeared to be related to the swelling ability of starch granules in the presence of limited water available for starch.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.181-184
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• 2009

A development of a composite solid propellant is carried out for an application to gas generators as an energy source of rocket system. With HTPB as a propellant binder which has 80% of particle loading ratio, a favorable rheology, and moderate curing properties at the range of $-50^{\circ}C{\sim}70^{\circ}C$, AN is selected as the first kind of oxidizer having the characteristics of a low flame temperature, minimal particle residual as well as nontoxic products. AP is the second oxidant for ballistic property control. A series of experiments for the improvement of physical properties were conducted and resulted in the propellant formulation having 30% of strain rate at 8 bar of max. stress.

• Journal of the East Asian Society of Dietary Life
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• v.19 no.6
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• pp.1025-1031
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• 2009

This study was conducted to investigate the effects of garlic powder on medium and cake flours using falling number and RVA tests, as well as alveograms and farinograms. The garlic powder was added to the medium and cake flour bases at 2 and 4%, respectively. Falling numbers increased with the addition of garlic powder. The peak viscosity of the medium flour containing 2% garlic powder was highest while that made with 4% garlic powder showed a decrease in peak viscosity. The addition of garlic powder increased the set-back value, thus the garlic powder did not have an anti-retrogradation effect. The alveographic P values of the treatment were lower than that of the control, but the L value was not significantly different. On the farinogram, water absorption was decreased in the flours containing garlic powder and development time was increased. In conclusion, the addition of 2% garlic powder is recommended to improve the volume and stability of cake.

• Journal of the Korean Graphic Arts Communication Society
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• v.23 no.2
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• pp.117-128
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• 2005

Printing inks are basically dispersions of solid pigment particles in a vehicle. Pigment flocculation and/or colloidal aggregates created by thixotrope additives form a three- dimensional network in the inks. This structure complicates the flow behaviour of inks. However, if the internal structure is formed under control, the printing process will benefit from it because the ink must satify rheological requirements over a very wide range of shear conditions. The presence of internal structure results in the following prominent non-Newtonian rheological properties: viscoelasticity, yield stress, shear thinning and thixotropy. If the components of printing inks were changed, the rheological characteristics such as viscosity, yield stress, viscoelasticity and tack value were considerably varied. Thus, in this paper, the effects of changing the content of rosin modified phenolic resin on rheological properties of the vehicle will be studied. For that, the rheological properties were found by flow, yield stress, creep and oscillation measurements using Bohlin C-VOR Rotational Rheometer. And Emulsion rheology and its microstructure will be investigated.

• Food Science and Biotechnology
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• v.16 no.1
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• pp.146-149
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• 2007

Dynamic rheological properties of hot pepper-soybean paste (HPSP) mixed with xanthan gum were evaluated at different gum concentrations (0.3, 0.6, and 0.9%) and fermentation times (12 and 24 week). Magnitudes of storage (G') and loss moduli (G") in the HPSP-xanthan gum mixture systems increased with an increase in frequency ($\omega$), while complex viscosity (${\eta}^*$) decreased. G' values were higher than the G" values over most of the frequency range (0.63-63 rad/sec), and were frequency-dependent. The dynamic moduli (G', G", and ${\eta}^*$) of the HPSP-xathan mixtures were lower than those of the control (0% gum). The differences between the dynamic moduli values at 12-week and 24-week fermentation decreased with increasing gum concentration, showing that xanthan gum can be used to stabilize and improve the viscoelastic rheological properties of HPSP. The G' value of the HPSP-xathan mixtures increased with an increase in gum concentration from 0.3 to 0.9%, whereas the G" decreased. The ability of xanthan gum to increase the elastic properties in the HPSP-xanthan mixture systems seemed to be the result of the incompatibility phenomena existing between xanthan gum and glutinous rice starch.

• Korean journal of food and cookery science
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• v.22 no.5 s.95
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• pp.591-599
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• 2006

The purpose of this study was to investigate the effect of the addition of various concentrations of sea mustard powder on the quality characteristics of Bacsulgi. The sea mustard powder was added to rice powder at ratios of 3, 5, 7, and 9%(w/w). The moisture contents and salinity of Bacsulgi were increased with the addition of sea mustard powder. The incorporation of sea mustard powder in Bacsulgi lowered the lightness values but increased the blueness and yellowness values. Rheology test showed that hardness was significantly (p<0.05) decreased with increasing sea mustard powder content. The springiness and cohesiveness were decreased, whereas the adhesiveness was increased, with increasing sea mustard powder content. Scanning electron microscopy showed that the size of the air cells increased and the surface of rice powder swelled with increasing sea mustard powder content. The result of sensory evaluation showed that there were significant (p<0.05) differences in the scores of smell and taste sensory characteristics among the samples. The overall eating quality was the highest in the control and decreased with increasing sea mustard powder level. The study results suggested that Bacsulgi prepared with up to 5% addition of sea mustard powder was as acceptable as Bacsulgi prepared without sea mustard powder.

• The Korean Journal of Rheology
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• v.11 no.2
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• pp.82-90
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• 1999

Electrorheological(ER) fluid is a material that shows the dramatic change of rheological properties under an electric field and responds reversibly in a few milliseconds. ER fluid's response to an electric field along with its fast switching capability allows ER devices to be precisely controlled. The real application with ER fluid, however, has many limitations to be overcome; temperature fluctuation, moisture, dust, aggregation, precipitation, and low yield stress, for example. The magnitude and the characteristics of yield stress of ER fluid plays an important role in practical applications. In this research, a dynamic simulation on the squeezing flow of the ER fluid was carried out. Numerical simulation on isolated chains was performed to find out the effect of hydrodynamic and electrostatic force depending on the chain location, the squeezing rate, and the chain structure. Suspension model that is composed of a large number of particles was also investigated. The increase of normal stresses as well as the existence of a yield stress at an earlier stage could be observed, and the effective control of the normal stresses could be achieved at an optimal condition of the hydrodynamic force and the electrostatic force.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.181-194
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• 2013

Landslides are known as gravitational mass movements that can carry the flow materials ranging in size from clay to boulders. The various types of landslides are differentiated by rate and depositional features. Indeed, flow characteristics are observed from very slow-moving landslides (e.g., mud slide and mud flow) to very fast-moving landslides (e.g., debris avalanches and debris flows). From a geomechanical point of view, shear-rate-dependent shear strength should be examined in landslides. This paper presents the design of advanced ring-shear apparatus to measure the undrained shear strength of debris flow materials in Korea. As updated from conventional ring-shear apparatus, this apparatus can evaluate the shear strength under different conditions of saturation, drainage and consolidation. We also briefly discussed on the ring shear apparatus for enforcing sealing and rotation control. For the materials with sands and gravels, an undrained ring-shear test was carried out simulating the undrained loading process that takes place in the pre-existing slip surface. We have observed typical evolution of shear strength that found in the literature. This paper presents the research background and expected results from the ring-shear apparatus. At high shear speed, a temporary liquefaction and grain-crushing occurred in the sliding zone may take an important role in the long-runout landslide motion. Strength in rheology can be also determined in post-failure dynamics using ring-shear apparatus and be utilized in debris flow mobility.