• Food Science of Animal Resources
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• v.38 no.3
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• pp.476-486
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• 2018

In this study, the droplet size distribution, rheological properties, and stability of dairy cream-based emulsions homogenized with different sucrose fatty acid ester (SFAE, a non-ionic small-molecule emulsifier) concentrations (0.08%, 0.16%, and 0.24% w/w) at different homogenization pressures (10 MPa and 20 MPa) were examined. Homogenization at a high pressure resulted in a smaller droplet size and narrower droplet size distribution. The D[4,3] (volume-weighted mean) and D[3,2] (surface-weighted mean) values of the emulsions decreased with an increase in the SFAE concentration. The flow properties of the emulsions homogenized with SFAE showed shear-thinning (n=0.21-0.46) behavior. The apparent viscosity (${\eta}_{a,10}$) and consistency index (K) of the homogenized emulsions were lower than those of the control sample that is non-homogenized and without SFAE, and decreased with an increase in SFAE concentration. The storage modulus (G') and loss modulus (G") of all emulsions homogenized with SFAE were also lower than those of the control sample. The stability of all emulsions with SFAE did not show any significant change for 30 d at $5^{\circ}C$. However, the emulsions stored at $40^{\circ}C$ were unstable over the storage period. Therefore, the addition of SFAE enhanced the stability of dairy cream emulsions during storage at refrigeration temperature ($5^{\circ}C$).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.4
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• pp.296-301
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• 2001

Electro-Rheological (ER) fluids belong to a class of colloidal suspensions whose global characteristics can be controlled by the imposition of an appropriate external electrical field upon the fluid domain. The ER fluids for smart hydraulic system are a class of colloidal dispersion which exhibit large reversible changes in their rheological behavior when subjected to external electrical fields. This paper presents experimental results on mechanical properties of an ER fluids subjected to electrical fatigues. As a first step, ER fluid is made of methyl cellulose(MC) ingredient choosing 25% of particle weight-concentration. Following the construction of test for mechanical properties of ER fluid, the shear stress, dynamic yield stress and current density of the ER fluids are experimentally distilled as a function of electric field cycles. The mechanical properties test of operated ER fluids are distilled and compared with those of unused ER fluids.

• 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.

• Elastomers and Composites
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• v.51 no.2
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• pp.113-121
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• 2016

Magneto-rheological elastomer (MRE) is a material which shows reversible and various modulus under magnetic field. Comparing to conventional rubber vibration isolator, MREs are able to absorb broader frequency range of vibration. These characteristic phenomena result from the orientation of magnetic particle (i.e., chain-like formation) in rubber matrix. In this study, silicone rubber was used as a matrix of MREs. Carbonyl iron particle (CIP) was used to give magnetic field reactive modulus of MRE. The surface of the CIP was modified with chemical reactants such as silane coupling agent and poly(glycidyl methacrylate), to improve interfacial adhesion between matrix and CIP. The mechanical properties of MREs were measured without the application of magnetic field. The results showed that the tensile strength was decreased while the hardness was increased with the addition of CIP. Also, surface modification of CIP resulted in the improvement of physical properties of MRE, but the degree of orientation of CIP became decreased. The analysis of MR effect was carried out using electromagnetic equipment with various magnetic flux. As the addition of CIP and magnetic flux increased, increment of MR effect was observed. Even though the surface modification of CIP gave positive effect on the mechanical properties of MRE, MR effect was decreased with the surface modification of CIP due to decrease of CIP orientation. Throughout this study, it was found that the loading amounts of CIP affected the mechanical properties of MRE, and surface property of CIP was an important factor on MR effect of MRE.

• Clean Technology
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• v.12 no.4
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• pp.198-204
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• 2006

The modification of biodegradable polycaprolactone was accomplished by reactive extrusion with various contents of free radical initiator. Reaction conditions were in the temperature range of $130^{\circ}C$ to $180^{\circ}C$ with initiator contents of 0.1, 0.3, 0.5 and 1.0 wt%. To characterize the modified polycaprolactone (PCL), molecular weight was measured by gel permeation chromatography(GPC) and thermal, mechanical and rheological properties as well as biodegradability were measured. The modified PCL (MPCL) with 1% of initiator showed ca. 20% increase in crystallinity and ca. 50% increase in tensile modulus. Also, a large increase in rheological properties such as complex viscosity, storage and loss modulus was observed. The biodegradability of most MPCL was higher than that of virgin PCL.

• Journal of the Korea Institute of Building Construction
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• v.15 no.3
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• pp.291-297
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• 2015

In this study, the evaluation and the analysis of the correlation between rheological properties and pumpability of high performance concrete, C80A which was applied to the height of from 200 m to 350 m in a super tall building, was carried out by measuring pumping pressure and flow rate, testing concrete properties at before and after pumping. As the results, C80A had satisfactory properties of fresh and hardened concrete to the requirements even after pumping and the maximum pumping pressure showed increase of 10~15% at every 50m higher pumping and the average flow rate showed the above $25m^3$ per hour which means proper productivity. Additionally it was verified that pumping pressure and friction factor in pipeline are inversely proportional to slump flow and showed a tendency to increase according to the higher T-500 value.

• Journal of Animal Science and Technology
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• v.63 no.2
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• pp.417-425
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• 2021

The use of edible insects to replace meat protein is important to ensure future global food security. However, processed foods using edible insects require development to enhance consumer perception. Here, we examined the physicochemical characteristics and rheological properties of emulsions prepared from different edible insect larvae. Three edible insect species (Tenebrio molitor, Allomyrina dichotoma and Protaetia brevitarsis seulensis) were used to prepare larval emulsions that were formulated with 65% of insect larvae, 20% of pork back fat, and 15% ice. The A. dichotoma emulsion had the highest pH and lightness, redness, and yellowness values, while the T. molitor emulsion had the lowest pH and lightness, redness, and yellowness values. The T. molitor emulsion had the highest hardness, gumminess, chewiness, and apparent viscosity values but the lowest springiness and cohesiveness values. According to the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, T. molitor had the thickest bands, followed by P. brevitarsis seulensis. The differential scanning calorimetry distributions for the T. molitor and A. dichotoma emulsions showed one peak, while that of the P. brevitarsis seulensis emulsion had two peaks. The collective results suggest that T. molitor was the most suitable candidate (of the three tested species) for use as a meat replacement in terms of its physicochemical and rheological properties. It is important that such properties of insect-based emulsions are maintained using various technologies.

• Composites Research
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• v.20 no.2
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• pp.21-26
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• 2007

This paper summarizes the design procedure and constructibility of an ECC (Engineered Cementitious Composite), which is a synthetic fiber-reinforced composite produced with the Portland cement-based mortar matrix. This study employs a stepwise method to develop useful ECC in construction field, which possesses different fluid properties to facilitate diverse types of processing (i.e., self-consolidating or spray processing). To control the rheological properties of the composite, the aggregates and reinforcing fibers were initially selected based on micromechanical analysis and steady-state cracking theory. The stability and consequent viscosity of the suspensions were then mediated by optimizing the dosage of the chemical and mineral admixtures. The rheological properties altered through this approach were revealed to be effective in obtaining ECC-hardened properties, represented by pseudo strain-hardening behavior in uniaxial tension, allowing the readily achievement of the desired function of the fresh ECC.

• Journal of Pharmaceutical Investigation
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• v.39 no.3
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• pp.185-199
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• 2009

Using a strain-controlled rheometer [Advanced Rheometric Expansion System (ARES)], the steady shear flow properties and the dynamic viscoelastic properties of $Antiphlamine-S^{(R)}$ lotion have been measured at $20^{\circ}C$ (storage temperature) and $37^{\circ}C$ (body temperature). In this article, the temperature dependence of the linear viscoelastic behavior was firstly reported from the experimental data obtained from a temperature-sweep test. The steady shear flow behavior was secondly reported and then the effect of shear rate on this behavior was discussed in detail. In addition, several inelastic-viscoplastic flow models including a yield stress parameter were employed to make a quantitative evaluation of the steady shear flow behavior, and then the applicability of these models was examined by calculating the various material parameters. The angular frequency dependence of the linear viscoelastic behavior was nextly explained and quantitatively predicted using a fractional derivative model. Finally, the strain amplitude dependence of the dynamic viscoelastic behavior was discussed in full to elucidate a nonlinear rheological behavior in large amplitude oscillatory shear flow fields. Main findings obtained from this study can be summarized as follows : (1) The linear viscoelastic behavior is almostly independent of temperature over a temperature range of $15{\sim}40^{circ}C$. (2) The steady shear viscosity is sharply decreased as an increase in shear rate, demonstrating a pronounced Non-Newtonian shear-thinning flow behavior. (3) The shear stress tends to approach a limiting constant value as a decrease in shear rate, exhibiting an existence of a yield stress. (4) The Herschel-Bulkley, Mizrahi-Berk and Heinz-Casson models are all applicable and have an equivalent validity to quantitatively describe the steady shear flow behavior of $Antiphlamine-S^{(R)}$ lotion whereas both the Bingham and Casson models do not give a good applicability. (5) In small amplitude oscillatory shear flow fields, the storage modulus is always greater than the loss modulus over an entire range of angular frequencies tested and both moduli show a slight dependence on angular frequency. This means that the linear viscoelastic behavior of $Antiphlamine-S^{(R)}$ lotion is dominated by an elastic nature rather than a viscous feature and that a gel-like structure is present in this system. (6) In large amplitude oscillatory shear flow fields, the storage modulus shows a nonlinear strain-thinning behavior at strain amplitude range larger than 10 % while the loss modulus exhibits a weak strain-overshoot behavior up to a strain amplitude of 50 % beyond which followed by a decrease in loss modulus with an increase in strain amplitude. (7) At sufficiently large strain amplitude range (${\gamma}_0$>100 %), the loss modulus is found to be greater than the storage modulus, indicating that a viscous property becomes superior to an elastic character in large shear deformations.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.5
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• pp.174-182
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• 2020

The printed electronics field using ink-jet printing technology is in the spotlight as a next-generation technology, especially ink-jet 3D printing, which can simultaneously discharge and precisely control various ink materials, has been actively researched in recent years. In this study, complex structure of an insulating layer and a conductive layer was fabricated with photo-curable silica ink and PVP-added Cu nano ink using ink-jet 3D printing technology. A precise photocured silica insulating layer was designed by optimizing the printing conditions and the rheological properties of the ink, and the resistance of the insulating layer was 2.43 × 10¹³ Ω·cm. On the photo-cured silica insulating layer, a Cu conductive layer was printed by controlling droplet distance. The sintering of the PVP-added nano Cu ink was performed using an IPL flash sintering process, and electrical and mechanical properties were confirmed according to the annealing temperature and applied voltage. Finally, it was confirmed that the resistance of the PVP-added Cu conductive layer was very low as 29 μΩ·cm under 100℃ annealing temperature and 700 V of IPL applied voltage, and the adhesion to the photo-cured silica insulating layer was very good.