• Elastomers and Composites
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• v.45 no.2
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• pp.106-111
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• 2010

Magneto-rheological elastomers (MREs) were manufactured by incorporation of magnetic responsible powder (MRP) into natural rubber and silicone rubber. The optimum loading amounts of MRP was 30 vol.% and the natural rubber based MRE (NR-MRE) showed better mechanical property than that of silicone rubber based MRE (S-MRE). However, the modulus shift ratio caused by S-MRE, measured by Self-modified Electromagnet Applied Fast Fourier Transform Analyser (SEFFTA), was higher than that of NR-MRE. The modulus shift ratio caused by NR-MRE was 10%, while the modulus shift ratio caused by S-MRE was 35.7%. The modulus shift ratio could be improved by orienting the magnetic direction of MRP before crosslinking the MRE. The degree of orientation of MRP was analyzed using SEM.

• Advances in concrete construction
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• v.6 no.5
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• pp.465-483
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• 2018

The most crucial factor determining the pumping performance of concrete is the characteristics of the lubricating layer formed between the pipe wall and the inner concrete. Thus, it is important to accurately identify the rheological properties of the lubricating layer to predict the pumping of concrete. In this study, a new method is proposed for measuring the rheological properties of the lubricating layer with improved convenience. To verify the new method, a pumping test was conducted with 337 m-long horizontal piping. The rheological properties of the lubricating layer were assessed by a previously verified method and the new method proposed in this study for a total of four concrete mixtures with design strength ranging from 27 MPa to 60 MPa. The correlation between the existing method and the new method in relation to the viscosity of the lubricating layer was determined, and it was possible to predict the pumping performance with an accuracy of about 88.5% using the viscosity of the lubricating layer obtained from this correlation.

• Food Science of Animal Resources
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• v.43 no.3
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• pp.540-551
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• 2023

Milk protein concentrate (MPC) is widely used to enhance the stability and texture of fermented dairy products. However, most research has focused on yogurt products, and the effects of MPC on sour cream characteristics remain unknown. Therefore, we investigated the effects of different MPC levels (0%, 1%, 2%, and 3% w/w) on the rheological, physicochemical, microbiological, and aroma characteristics of sour creams in this study. We found that MPC supplementation stimulated the growth of lactic acid bacteria (LAB) in sour creams, resulting in higher acidity than that in the control sample due to the lactic acid produced by LAB. Three aroma compounds, acetaldehyde, diacetyl, and acetoin, were detected in all sour cream samples. All sour creams showed shear-thinning behavior (n=0.41-0.50), and the addition of MPC led to an increase in the rheological parameters (η_a,50, K, G', and G"). In particular, sour cream with 3% MPC showed the best elastic property owing to the interaction between denatured whey protein and caseins. In addition, these protein interactions resulted in the formation of a gel network, which enhanced the water-holding capacity and improved the whey separation. These findings revealed that MPC can be used as a supplementary protein to improve the rheological and physicochemical characteristics of sour cream.

• Transactions of Materials Processing
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• v.14 no.4 s.76
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• pp.338-350
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• 2005

Recently, in the field of automobile industry, to solve the problem of reducing the weight of automobile for the improvement of fuel efficiency and the protection of environment, the aluminum alloy parts have been substituted for the steel parts. However, the aluminum alloy does not have as good mechanical property as the steel part. To improve the mechanical property, the semi-solid die casting process is performed to make automobile parts. In the fabrication of semisolid material the control of the liquid segregation is very important to improve the material properties of aluminum alloy. In the present paper we examine the influence of the liquid segregation by the injection conditions in the semi-solid die casting has been investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.271-276
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• 2003

This study is about the rheological properties of cement slurry using admixtures. The variables are the type of cement(Type I, II, IV, V) and the substitution ratio of admixtures such as fly ash and slag. As a result of measuring the fluidity of various types of cement slurry at the early stage, type 2, type 4 and type 5 showed the similar property. The fluidity of type 1 and ternary blended cement was low. it is thought that it is because of the high $C_3$A content. The cement slurries containing mineral admixtures were superior in the property of fluidity retention.

• Food Science and Biotechnology
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• v.17 no.4
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• pp.705-712
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• 2008

Sweet potato starch was modified using Thermus aquaticus $\alpha$-1,4-glucanotransferase ($Ta{\alpha}GT$), and its structural and rheological properties were investigated. $Ta{\alpha}GT$-modified starch had a lower amylose level and molecular weight than raw starch. The chain length distribution showed an increased number of short and long branched chains and the formation of cycloamyloses. Compared with raw starch, $Ta{\alpha}GT$-modified starch displayed a lower gelatinization enthalpy and a wider melting temperature range. The X-ray diffraction of $Ta{\alpha}GT$-modified starch was a weak V-type pattern with distinct sharp peaks at 13 and $20^{\circ}$. Scanning electron micrographs of modified starch exhibited big holes on the surface and the loss of granular structure. The frequency sweep measurement revealed that the gel of $Ta{\alpha}GT$-modified starch was more rigid than raw starch gel. However, the structure of modified starch gel was destroyed by heating at $75^{\circ}C$, and a firm gel was re-formed by subsequent storage at $5^{\circ}C$, indicating thermoreversible property.

• The Korean Journal of Food And Nutrition
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• v.18 no.4
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• pp.287-294
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• 2005

Three different gruels; $100\%$ rice, $70\%$ rice and $30\%$ sprouted black bean with sprout, and $100\%$ rice and $70\%$ sprouted black bean, were prepared. Organoleptic, chemical and rheological properties were compared according to the heating time and the quantity of water. Regarding to the the rheological properties, the gruel with $30\%$ rice and $70\%$ sprouted black bean with sprout revealed the lowest level of solidity and the highest level of viscosity among these three kinds of gruels. The chemical properties; pH, total sugar content and amylose content were similar each other. In terms of organoleptic properties, the best gruel was made with $30\%$ rice and $70\%$ sprouted black bean with sprout. In addition, the best cooking condition was found that 9 times of water to the weight of rice and sprouted black bean with sprout, was used follows by 40 minutes' heating.

• Transactions of Materials Processing
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• v.12 no.1
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• pp.3-10
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• 2003

The formation of surface defects associated with Jotting in injection molding is related to the geometries of cavity and fate, operational conditions and the rheological properties of polymer. In this study we have examined jetting phenomena in injection molding process for the throe kinds of PCs which have different molecular weights and structures, PBT and PC/ABS alloy with several injection speeds. We have used various cavity shapes those are tensile, flexural and impact test specimens with various gates and cavity thicknesses. Through this study we have observed that the jetting is related to the dic swell of material. This means that the jotting is strongly affected by the elastic flow property rather than the viscous flow property in viscoelastic characteristics of molten polymer. Different resins have different elastic properties, and elastic flow behavior depends on the shear rate of flow, i.e. injection speed. Large die swell would eliminate jetting however, the retardation of die swell would stimulate jetting. In the point of mole design, reducing the thickness ratio of cavity to gate can reduce or eliminate jetting regardless of amount of elasticity of polymer melt.

• Korean Chemical Engineering Research
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• v.49 no.3
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• pp.342-347
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• 2011

The effects of compatibilizers on the mechanical and rheological properties of PP/PCL and TPO/PCL blends have been studied. The thermoplastic polyolefin (TPO) consists of PP (80 wt%), EPDM (15 wt%) and Talc (5 wt%). Maleic anhydride grafted polypropylene (PP-g-MAH) and maleic anhydride grafted styrene-(ethylene-co-butene)-styrene copolymer (SEBS-g-MAH) were used as compatibilizers. In mechanical properties of PP/PCL and TPO/PCL blends, tensile strength was increased when PP-g-MAH was used as a compatibilizer, and impact strength was increased when SEBS-g-MAH was used as a compatibilizer. From the results of SEM morphology of PP/PCL blend, PCL droplet size was decreased by the addition of PP-g-MAH. From the results of rheological property, complex viscosity of the PP/PCL and TPO/PCL blends did not change appreciably when the compatibilizers were added. From the results of mechanical, morphological and rheological properties of the blends, PP-g-MAH acted as a compatibilizer to increase the tensile strength of the PP/PCL and TPO/PCL blends. While SEBS-g-MAH acted as a impact modifier to increase the impact strength of the PP/PCL and TPO/PCL blends.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.222-227
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• 2002

MR(Magneto-rheological) fluid is smart fluid that can change its characteristics then magnetic fields are applied. Recently, many researches have been performed on this MR fluid for the application in a vareity of areas including automobile shock absorbers. This paper describes the design procedure of a MR damper and the analysis results of its dynamic characteristics. MR fluid in the magnetic field shows initial yield shear stress and increasing resistive viscosity with final saturation thereafter. Herschel-Bulkley model is used to simulate the flow characteristics of MR fluid and magnetic analysis is used to identify the magnetic property of the MR fluid in the orifice of the damper. The dynamic characteristics of the damper was predicted and compared with the experimental results for typical sinusoidal excitations.