• Food Science and Biotechnology
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• 제14권2호
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• pp.233-237
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• 2005

Rheological properties of acorn flour-guar gum mixtures (4% w/w) at different guar gum concentrations (0, 0.2, 0.4, 0.6, and 0.8% w/w) were evaluated in steady and dynamic shear. The acorn flour-guar gum mixtures at $25^{\circ}C$ showed high shear-thinning flow behavior (n= 0.20-0.27). Consistency index (K), apparent viscosity (${\eta}_{a,100}$), and Casson yield stress (${\sigma}_{oc}$) increased with the increase in guar gum concentration. Within the temperature range of $25-70^{\circ}C$, the {\eta}_{a,100}$ of mixtures obeyed the Arrhenius relationship with high determination coefficient ($R^2=\;0.974-0.994$). Activation energy values (5.37-6.77 kJ/mole) of acorn flour dispersions in the mixtures with guar gum (0.2-0.8%) were much lower than that (12.5 kJ/mole) of acorn flour dispersion (0% guar gum). Storage modulus (G'), loss modulus (G"), and complex viscosity (${\eta}^*$) increased with the increase in guar gum concentration. Dynamic rheological data of 1n (G', G") versus ln frequency (w) of guar gum-acorn flour mixtures had positive slopes with G' greater than G" over most of the frequency range, indicating that they exhibited weak gel-like behavior.

• Elastomers and Composites
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• 제53권1호
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• pp.6-12
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• 2018

Styrene-butadiene Rubber (SBR) Latex composites, incorporated with cellulose/starch-silica hybrids synthesized by gel-adsorption method, were filled into rubber by the latex compounding method. The structure morphology, mechanical properties, and thermodynamic properties of gel-silica hybrids were characterized. The states of hybrids which used as fillers were also characterized by SEM. As the fillers ratio increased, the difference for storage modulus of samples had been morphology by rubber process analyzer (RPA). Then, as more fillers ratio was filled into the matrix, the best tensile strength result, and the largest modulus value were also proved by UTM and RPA. As for thermal stability, increase in the ratio of fillers led to higher initial decomposition temperature, which was also proved by TGA. The swelling ratio of samples has also been characterized. From the results of all the tests, cellulose-silica hybrid showed the best results as a filler, and the best filling ratio of this hybrid is about 10 phr, which has the best storage modulus and great tensile strength.

• 한국식품영양과학회지
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• 제32권7호
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• pp.1046-1052
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• 2003

Viscoelastic behavior of oxidized starch gel, modified with sodium hypochlorite (NaOCl) and the adding effects of protein in oxidized starch gel was studied by dynamic viscoelastic measurement. The storage modulus(G′) of starch gel increased with the increase of starch concentration. They showed higher value when starch suspension was treated to 95$^{\circ}C$ rather than 85$^{\circ}C$. Consistency of starch gel was decreased over 1.0% active Cl/g starch when heated to 95$^{\circ}C$, which means that the swelling of starch granules increased with concentration of NaOCl and showed more sensitive against shear. As the extent of oxidation increased, starch granules were easily destroyed. Therefore, it is hard to separate between compartment of leached-out amylose and that of amylopectin, which means that the ability of gel formation was reduced. When oxidized starches were gelatinized in presence of soy protein and sodium caseinate, it was found that G′ decreased, and frequency dependence of G′ and G" increased with the increased degree of oxidation in starch. The reduce of starch-protein interaction was thought to be through the dissociation of the branched amylopectin, which playa leading role in protein interaction, with the oxidation of starch.

• Elastomers and Composites
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• 제39권4호
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• pp.274-280
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• 2004

신발중창용으로 사용되는 IP, PH 그리고 PU 발포체의 경도가 온도변화에 따른 발포체의 저장탄성율(G'), 충격력, 반발탄성율 등에 미치는 영향을 고찰하였다. 측정 온도가 감소함에 따라 PU 발포체의 저장탄성율은 현저히 증가하였으나, PH 및 IP 발포체의 경우 측정 온도에 따른 영향을 크게 받지 않는 것으로 나타났다. $20^{\circ}C$ 이하의 온도에서는 측정 온도가 감소함에 따라 PU 발포체의 충격력은 증가하는 현상을 나타내었으나 PH와 IP 발포체의 충격력은 온도에 큰 영향을 받지 않는 것으로 나타났다. $20^{\circ}C$ 이상의 온도에서 PH와 IP 발포체의 충격력은 현저하게 증가하였으나, PU 발포체의 경우는 큰 변화가 없었다. $-20^{\circ}C$에서 $40^{\circ}C$까지의 온도 영역에서는 PU 발포체의 반발탄성율이 PH와 IP의 경우 보다 낮게 나타났다.

• 한국지반공학회지:지반
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• 제12권3호
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• pp.83-98
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• 1996

이 논문에서는 역순법 원리를 이용한 역해석 결과를 제시하였다. 국내에서 건설된 두 곳의 지하비축기지 공사 중에 계측한 자료를 이용하여 비축기지 진입터널 주위 암반의 변형계수와 초기 지압을 계산하였다. 역해석에서 얻어진 결과를 입력자를로 하여 유한요소해석을 수행하였으며 그 결과를 계측치와 비교, 검토하였다.

• 한국염색가공학회지
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• 제11권6호
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• pp.7-17
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• 1999

Aminophosphazene derivatives were prepared from hexachlorocyclotriphosphazene and used for the curing agents of epoxy resins. The effect of the curing agent on the dynamic viscoelastic properties, flame proofing, and heat resistance of the cured epoxy resins were investigated and compared with those for the epoxy resins cured with aliphatic and aromatic amines. The epoxy resin cured by 1,1-diamino-3,3,5,5-tetrachlorocyclotriphosphazene showed the highest storage modulus and glass transition temperature when cured at 19$0^{\circ}C$ for 6 hours. The epoxy resins cured with phosphazene derivatives showed superior flame proofing to those with aliphatic amine and aromatic amine. Particularly it is an effective curing agent for epoxy resins to enhance the storage modulus, flame proofing and resistance to heat.

• Elastomers and Composites
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• 제27권1호
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• pp.13-19
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• 1992

In this work, properties of ABS/AES blends were investigated. Blends were prepared by casting from THF. The thermal stability, light resistance, storage modulus and flame retardancy were measured by thermogravimetric analysis, cole. difference in Fade-o-meter, Rheovibron, and limiting oxygen index(LOI). The thermal stability, light resistance and storage modulus increased with increasing contents of AES. ABS and AES showed similar LOI. The LOI of the ABS/AES blends increased with rising contents of AES but all the blends were found to be flammable. It was observed that ABS and AES was incompatible from the morphology by scanning electron microscope(SEM).

• Elastomers and Composites
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• 제52권1호
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• pp.17-21
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• 2017

The optimum mixing conditions of silica and silane containing rubber composites were evaluated by investigating the properties of rubber composites prepared with a silica composition of 10, 20, 40, 60, and 80 g, respectively. The crosslinking rate decreased with increasing silica content, with he promoters being adsorbed on the silica surface with in the rubber composite. As a result, the increase in crosslinking time resulted in the destruction of the silica structure. The increase of the bound rubber content due to the destruction of the silica structure inhibited the chain motion of the polymer molecules and reduced the cohesion of the silica itself. Finally, the increase of silica content showed the increase of hardness, tensile strength, and storage modulus of rubber composites.

• Food Science and Biotechnology
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• 제14권6호
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• pp.871-874
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• 2005

The effect of rice starch at different concentrations (0, 4, 6, and 8%) on dynamic rheological properties of surimi sols was investigated by small-deformation oscillatory measurements at $10^{\circ}C$ and during heating from 10 to $95^{\circ}C$. Dynamic frequency sweeps at $10^{\circ}C$ showed that the magnitudes of storage modulus (G') decreased with increasing starch concentration while those of tan $\delta$ increased. G' values of surimi-rice starch sols during heating decreased with increasing starch concentration, indicating that the pattern of G' changes during heating was influenced by the concentration of the added rice starch. In general, the characteristic G' thermograms of all samples showed a similar sol-gel transition pattern.

• Korea-Australia Rheology Journal
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• 제17권2호
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• pp.41-45
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• 2005

As an effort to explore the effective use of carbon nanotubes as a reinforcing material for advanced nano-composites with polymer matrices, multi-walled carbon nanotubes (MWNTs) were successfully incorporated into polystyrene (PS) via in-situ bulk polymerization. Various experimental techniques revealed that the covalent bonds formed between PS radicals and acid-treated carbon nanotubes are favorable resulting in an effective load transfer. The enhanced storage modulus of the nanocomposites suggests a strong possibility for the potential use in industrial applications.