• Preventive Nutrition and Food Science
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• v.22 no.1
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• pp.62-66
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• 2017

This study was conducted to determine the rheological properties of gochujang and chogochujang at different temperatures (25, 35, and $45^{\circ}C$). Rheological properties of the samples were determined using a rotational rheometer at a shear range of 1 to $40s^{-1}$. Gochujang and chogochujang were found to be non-Newtonian fluids according to the Herschel-Bulkley model. Yield stress and consistency coefficient of gochujang at different temperatures were higher than those of chogochujang, whereas the opposite was observed for flow behavior index. Moreover, all rheological properties of gochujang and chogochujang decreased with increasing temperature. The consistency coefficient was related to temperature using an Arrhenius-type relationship. Gochujang (14.48 kJ/mol) had slightly higher activation energy than chogochujang (14.03 kJ/mol).

• Journal of the Korean Ceramic Society
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• v.34 no.5
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• pp.528-534
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• 1997

There have been many studies on the preparation of slip, forming and drying in the slip casting process. However, is has not been yet on the rheological properties of consolidated body which largely affect on the workability. It was investugated that the rheological properties of the consolidated bodies formed by slip casting in the form of cakes from well dispersed(slip C) and weakly agglomerated slip(slip B) in the clay and clay-fly ash systems. The state of dispersion of slip was found to affected the critical moisture content which was largely affected by the pore and moisture distribution of the consolidated body. The cake C show lower critical moisture content than cake B in the clay system. However, the cake B gives lower critical moisture content than cake C in the clay-fly ash system.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.20 no.1
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• pp.52-63
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• 1994

It was investigated that the effects of surfactant to cosurfactant ratio on the stability and rheological properties of o/w microemulsion. The stability of microemulsion was good in the surfactant to cosurfactant ratio 20/40 - 30/30. In the point of rheological properties, a yield stress meande the inner structure formation was detected and the area of hysteresis loop was increased with increasing of surfactant content of the ratio. The microemulsion prepared by the Microfluidizer was characterized by rheopetic.

• Fibers and Polymers
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• v.6 no.4
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• pp.289-296
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• 2005

Biodegradable nanocomposites were prepared by mixing a polymer resin and layered silicates by the melt intercalation method. Internal structure of the nanocomposite was characterized by using the small angle X-ray scattering (SAXS) and transmission electron microscope (TEM). Nanocomposites having exfoliated and intercalated structures were obtained by employing two different organically modified nanoclays. Rheological properties in shear and extensional flows and biodegradability of nanocomposites were measured. In shear flow, shear thinning behavior and increased storage modulus were observed as the clay loading increased. In extensional flow, strain hardening behavior was observed in well dispersed system. Nanocomposites with the exfoliated structure had better biodegradability than nanocomposites with the intercalated structure or pure polymer.

• Journal of the Korean Applied Science and Technology
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• v.32 no.4
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• pp.661-668
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• 2015

The surface rheological properties of polymer monolayer show complicated non-linear viscoelastic flow phenomena when they are subjected to spreading flow. These spreading flow properties are controlled by the characteristics of flow units. The kinetics of the formation of an interfacial film obtained after spreading poly(diisobutylene maleic acid) at air-water interface were studied by measuring of the surface pressure with time. The experimental data were analyzed theoretically according to a nonlinear surface viscoelastic model. The values of dynamic modulus, static modulus, surface viscosities and rheological parameters in various area/ monomer were obtained by appling experimental data to the equation of nonlinear surface viscoelastic model.

• Korea-Australia Rheology Journal
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• v.20 no.4
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• pp.227-233
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• 2008

High impact polystyrene (HIPS)/organoclay nanocomposites via in situ polymerization were synthesized and their rheological properties were investigated. For the study, two types of organoclays were used: a commercially available organoclay, Cloisite 10A (C10A), and a laboratory-prepared organoclay having a reactant group, vinylclay (ODVC). The X-ray diffraction and transmission electron microscopy experiments revealed that the HIPS/ODVC nanocomposite achieved an exfoliated structure, whereas the HIPS/C10A nanocomposite achieved an intercalated structure. In the small-amplitude oscillatory shear experiments, both storage modulus and complex viscosity increased with increasing organoclay. A pronounced effect of the organoclay content was observed, resulting in larger storage modulus and stronger yield behavior in the low frequency region when compared to neat HIPS. The crossover frequencies associated with the inverse of a longest relaxation time decreased as the organoclay content increased. Over a certain value of ODVC content, a change of pattern in rheological properties could be found, indicating a solid-like response with storage modulus greater than loss modulus at all frequencies.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.5
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• pp.860-864
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• 2000

The steady and dynamic shear rheological properties of traditional kochujang fermented at three different temperatures (20${^circ}C$, 25${^circ}C$ and 30${^circ}C$) were studied. Flow of kochujang samples showed time dependence, which was quantitatively described by the Weltman model, Kochujang samples were highly shear thinning fluids (n=0.25~0.27) with large magnitudes of Casson yield stresses (1.09~1.21 kPa). Consistency index (K) and apparent viscosity (${\eta}_{a,20}$) increased with increase in fermentation temperature of kochujang. Storage (G') and loss (G") moduli increased with increase in frequency (ω), while complex viscosity (${\eta}^{\ast}$) decreased. Based on dynamic shear data, kochujang samples exhibit structural properties similar to weak gels. The complex and steady shear viscosities at different fermentation temperatures followed the Cox-Merz superposition rule with the application of the shift factor (a=0.011~0.016).

• Journal of the Korean Society of Visualization
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• v.19 no.1
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• pp.81-87
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• 2021

Extensional flow of viscoelastic fluids is widely utilized in various industrial processes such as electrospinning, 3D printing and plastic injection molding. Extensional rheological properties, such as apparent viscosity and relaxation time, play an important role in the design and evaluation of the viscoelastic fluid-involved processes. In this work, we propose a lab-built capillary breakup extensional rheometer (CaBER) based on flow image processing to investigate the capillary breakup of polyethylene oxide (PEO) solution and its extensional rheological properties. We found that the apparent extensional viscosity and extensional relaxation time of the PEO solution are independent of the strike time. The proposed CaBER is expected to be applied to characterization of the extensional rheological properties of viscoelastic fluids at low cost with high precision.

• Korea-Australia Rheology Journal
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• v.11 no.3
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• pp.219-223
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• 1999

The effects of the transreactions on the rheological properties have been found in the poly(ethylene 2, 6-naphthalate) (PEN) and poly (ethylene terephthalate) (PET) blends. The rheological properties were very much dependent on the blend compositions, which, in turn, were related to extent of the reactions. In particular, a blend with 50/50 wt% composition exhibits an unusual and remarkable decrease in complex viscosity and it may be related to the randomness of the copolymer structure through transreactions. It has been identified by investigating the extent of transreactions and block length of the copolymer from the (ethylene 2, 6-naphthalate) (EN) and (ethylene terephthalate) (ET) units from $^1{H}$ n.m.r. spectra.

• Structural Engineering and Mechanics
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• v.51 no.1
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• pp.1-13
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• 2014

This paper reports an experimental study into the rheological behaviour of self consolidating concrete (SCC). The investigation aimed at quantifying the impact of the varying amounts of mineral admixtures on the rheology of SCC containing natural sand. Apart from the ordinary Portland cement (OPC), the cementitious materials such as fly ash (FA), ground granulated blast furnace slag (GGBS) and micro-silica (MS) in conjunction with the mineral admixtures were used in different percentages keeping the mix paste volume and flow of concrete constant at higher atmospheric tempterature ($30^{\circ}$ to $40^{\circ}C$). The rheological properties of SCC were investigated using an ICAR rheometer with a four-blade vane. The rheological properties of self-consolidating concrete (SCC) containing different mineral admixtures (MA) were investigated using an ICAR rheometer. The mineral admixtures were fly ash (FA), ground granulated blast furnace slag (GGBS), and micro silica (MS). The results obtained using traditional workability results are compared with those obtained using ICAR rheometer. The instrument ICAR (International Center for Aggregate Research) rheometer employed in the present study for evaluating the rhelogical behaviour of the SCC is found to detect systematic changes in workability, cementitious materials, successfully. It can be concluded that the rheology and the slump flow tests can be concurrently used for predicting the flow behaviours of SCC made with different cementitious materials.