• 한국식품과학회지
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• 제23권1호
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• pp.57-61
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• 1991

동진벼(일반계)와 삼강벼(다수계) 전분의 특성을 이해하기 위하여 가열 및 알칼리 호화액에 대한 리올로지 특성을 회전점도계로 비교 검토하였다. 가열 호화액의 리올로지 특성값은 품종간의 차이가 크지 않았으며, 활성화 에너지는 동진벼 전분이 6.73 및 삼강벼 전분이 6.35 Kcal/mol 이었다. 알칼리 호화액의 리올로지 특성값은 뚜렸한 차이를 나타내었으며, 삼강벼 전분의 항복응력 및 점조도지수 값이 동진벼 전분보다 컸다. 가열 호화액은 알칼리 호화액보다 의가소성, 항복응력 및 점조도지수 값이 큰 결과를 보였다.

• Nuclear Engineering and Technology
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• 제52권8호
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• pp.1714-1723
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• 2020

This study aims at characterizing the rheological properties of uranium oxide powders for nuclear fuel pellets manufacturing. The flowability of these powders must be compatible with a reproducible filling of press molds. The particle size distribution is known to have an impact on the rheological properties and fine particles (<100 ㎛) are suspected to have a detrimental effect. In this study, the impact of the particle size distribution on the rheological properties of UO₂ powders was quantified, focusing on the influence of fine particles. Two complementary approaches were used. The first approach involved characterizing the powder in a static state: density, compressibility and shear test measurements were used to understand the behavior of the powder when it is transitioned from a static to a dynamic state (i.e., incipient flow conditions). The second approach involved characterizing the behavior of the powder in a dynamic state. Two zones, corresponding to two characteristic behaviors, were demonstrated for both types of measurements. The obtained results showed the amount of fines should be kept below 10 % wt to ensure a robust mold filling operation (i.e., constant mass and production rate).

• Journal of Microbiology and Biotechnology
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• 제12권5호
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• pp.740-745
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• 2002

The current study was conducted to identify the differences in the rheological properties of Chlorella sp. powder cultured in a fermentor and in a pond-like environment. Cells. cultured in the same media were harvested and spray dried. The biomass yield from the fermentor culture was 4.7% (dry basis), while that from the pond was 4.3% (dry basis). Measurements of the loose bulk density, tapping test, Hausner's ratio, and compressibility test all revealed differences between the rheological properties of the Chlorella sp. from the two cultivation systems. Although both the fermentor and pond cultured Chlorella sp. showed the same angle of repose, the mean size of the cells was 2.26 $\mu\textrm{m}$ and 2.89 $\mu\textrm{m}$, respectively. The weight of the Chlorella sp. tablets cultured in the fermentor and pond was 0.663 g/tablet and 0.593 g/tablet, respectively, while the friability of the tablets was 21% and 41%, respectively. Observation by Transmission Electron Microscope (TEM) showed that the cell wall of the Chlorella sp. cultured in the fermentor was thinner and more spherical than that cultured in the pond, thereby providing the main characteristic rheological properties of the powder.

• 한국세라믹학회지
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• 제42권11호
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• pp.737-742
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• 2005

Rheological properties of ordinary portland cement (OPC) containing metakaoline (MK), granulated blast furnace slag (GBS) and polycarboxylate type superplasticizer (PCA) were investigated using a mini-slump test, sedimentation test and viscometer. Fluidity of cement pastes containing MK (OPC-MK, OPC-MK-GBS systems) with PCA were higher than those of the cement pastes without MK(OPC, OPC-GBS systems). Colloid suspensions with $0.1\%$ PCA were changed from stable sedimentation behaviors to flocculation behaviors in the OPC-MK, OPC-GBS and OPC-MK-GBS systems. The colloid suspensions showed stable sedimentation behaviors with PCA greater than $0.2\%$. The OPC system showed shear thinning behavior. However, the other systems showed weak shear thinning behaviors with PCA. Rheological properties of cement pastes were improved when MK and GBS were contained together. The rheological properties of OPC-MK, OPC-GBS and OPC-MK-GBS systems were improved by PCA added greater than $0.2\%$.

• Advances in concrete construction
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• 제13권5호
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• pp.395-410
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• 2022

This study collected the results of material tests and full-scale pumping tests using 127 types of concrete mixtures with compressive strength ranging from 24 to 200 MPa. The results of 242 material tests showed high correlations between the viscosity of the lubricating layer and concrete, between the slump and the yield stress of concrete, between the water-binder ratio and the viscosity of lubricating layer, and between the time required to reach 500 mm of slump flow and concrete viscosity. Based on these correlations, pumpability was predicted using 101 pumping test conditions, and their accuracy was compared to the actual test results. When the rheological properties of concrete and the lubricating layer were directly measured, the prediction result showed the highest accuracy. A high accuracy can be achieved when the measured viscosity of the lubricating layer, a key determinant of concrete pumpability, is reflected in the prediction of pumpability. When measuring rheological properties is difficult, the slump test can be used to quantitatively predict the pumpability despite the lower accuracy than those of other prediction methods.

• 대한화학회지
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• 제50권6호
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• pp.447-453
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• 2006

수화 겔의 유변성질에 있어서 합성 조건과 수화 물 양의 영향이 연구되었다. cone-plate 레오메타를 사용하여 polyacrylamide 수화 겔의 비 뉴톤 유동 곡선을 얻었다. 이렇게 얻은 유동곡선에 유동에 대한 비뉴톤식을 적용하여 유변 파라메타를 계산하여 얻었다. polyacrylamide 수화 겔은 전단속도가 증가함에 따라 구조가 약해지는 흐름변성 현상을 나타낸다. 이들 유동성질은 유동단위의 특성과 유동 분절사이의 상호 관계에 의해서 나타나는 물질적인 성질이다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2003년도 추계학술발표논문집
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• pp.139-147
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• 2003

Coater runnability of the paper coating and final product properties can be affected by the immobilization of coating color and the dewatering into the base paper. During the dewatering, the rheological properties and solids content of a coating are dramatically changed. For the purpose of obtaining better coater runnability and high quality of coater paper many papermakers are trying to improve the water retention of paper coatings by using some additives such as thickener and co-binder. In this study, we tried to investigate the rheological properties and the immobilization point of coatings with immobilization cell during the dewatering of coatings.

• International Journal of Industrial Entomology and Biomaterials
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• 제27권1호
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• pp.180-184
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• 2013

Recently, silk sericin has attracted the attention of researchers owing to its useful properties as a biomaterial including 1) good wound healing and cell activities, 2) fast gelation character, and 3) high water retention property. In the present study, silk sericin was prepared using different extraction times in hot water and the effect of extraction time on the rheological properties of sericin solutions and gels was examined. It was found that the production yield of sericin increased with extraction time. The shear viscosity of sericin solutions and gels decreased with increasing extraction time due to a decrease in sericin molecular weight. When the sericin solution transformed to a gel, the viscosity increased and the shear thinning behavior was more evident. In addition, the shear stress measurements indicated that the slip between the sericin samples and the measuring plate of the rheometer was increased by the gelation of sericin. The compression strength of sericin gel could be increased remarkably (by more than 100 fold) by preparation using the freezing and thawing method.

• 한국인쇄학회지
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• 제22권2호
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• pp.1-12
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• 2004

In lithography based on repulsion of ink and water emulsification is inevitably generated. Thus it is necessary to analyze relationship between printability and physical and chemical properties of emulsified ink. Transfer rate of ink is one of the important factor deciding print quality. And it is closely concerned with rheological properties of emulsified ink. Rheological properties such as flow, yield, plastic viscosity, creep, oscillation and tack tests were measured. In order to examine printability of emulsified ink, ink transfer equations, density, ink film thickness and gloss were measured.

• 폴리머
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• 제38권4호
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• pp.425-433
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• 2014

In this study, microstructure and gel content (C-C) of polybutadiene rubber (PBR) were investigated using various techniques including ASTM D 3616, attenuated total reflectance Fourier transform infrared spectrometry (ATR FTIR), differential scanning calorimetry (DSC) and nuclear magnetic resonance spectroscopy (NMR). The ATR FTIR spectra of the samples were investigated to determine the cis, trans, 1, 2-vinyl and the C-C gel content in PBR. The absorbance ratios of specific peaks in different grades of PBR were correlated with the C-C gel content measured by the ATR FTIR techniques. Physico-mechanical and rheological properties of rubber compounds based on BR with various amounts of gel were determined. The results showed that there is an acceptable correlation between these properties and the C-C gel content of PBR.