• Geomechanics and Engineering
• /
• 제21권1호
• /
• pp.53-62
• /
• 2020

Rheological processes in the rock mass for the stress-strain analysis are quite important when considering the construction of underground structures in soft rock masses, particularly in case of construction in several stages. In the analysis, it can be assumed that the reinforced concrete structure is slightly deformable in relation to the rock mass, and the rheological stress redistribution happens at the expense of the elements of rock mass. The basic elements of rheological models for certain types of rock mass and analysis of these models are presented in the first part of this paper. The second part is dedicated to the analysis of rheological processes in marl rock mass and the influence of these processes on the reinforced-concrete tunnel structure.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2009년도 춘계학술대회 논문집
• /
• pp.98-102
• /
• 2009

The magneto-rheological fluid expresses different cohesiveness according to the strength of the external electric current. To manufacture the magneto-rheological fluid damper that uses such characteristics of the fluid, a flow analysis of the inner damper was conducted to forecast the damper's capacity. In addition, using the finite element method software, analysis on the characteristics of electromagnetic field around the coil operation unit inside the damper. Based on the result of the analysis, a single core damper and a double core damper were built and tested for their dynamic function. Based on the result of the experiment, the propriety of the flow analysis was demonstrated, and the proposed model was verified.

• 한국소음진동공학회논문집
• /
• 제14권6호
• /
• pp.470-477
• /
• 2004

This study shows the design process of a MR damper for semi-active suspension systems. Damping force characteristics of the designed damper was predicted through the flow analysis and magnetic analysis. The predicted results were compared with the experimental results and the initial design specification was modified according to the results.

• 식품과학과 산업
• /
• 제51권1호
• /
• pp.2-7
• /
• 2018

Increasing attention has been paid to rheological approaches in the food industry due to great awareness of the quality control of foods by objective analysis. Therefore, a lot of food manufacturers started to make a great of effort to instrumentally investigate the rheological properties of foods. However, the appropriate utilization of rheological instruments in the field of food science has been met with numerous technical challenges because of the lack of fundamental knowledge and knowhow. In this article, a variety of rheological instruments conventionally used in the food industry are reviewed. In addition, new rheological instruments that have been rapidly growing in popularity are introduced for potential applications. This article may provide an opportunity for the food industry to move toward the active utilization of rheological instruments.

• Geomechanics and Engineering
• /
• 제29권3호
• /
• pp.259-267
• /
• 2022

The rheological and penetration characteristics of sodium alginate and xanthan gum aqueous solutions were analyzed for the development of biopolymer-based injection materials. The results of viscosity measurements for the rheological characteristics analysis show that all aqueous biopolymer solutions exhibit a tendency for shear-thinning, i.e., the apparent viscosity decreases as the shear rate increases. In addition, a regression analysis using several models (Power-law, Casson, Sisko, and Cross) was applied to the shear-thinning fluid analysis results, the highest accuracy was determined by applying the power-law model. The micromodel experiment for the penetration characteristics analysis determined that all biopolymer aqueous solutions show higher pore saturation than water, and that pore saturation tends to increase as the flow rate and concentration increases. When comparing the rheological and penetration characteristics of the biopolymer aqueous solution used in this study, the xanthan gum aqueous solution showed a fully developed shear-thinning tendency, unlike the sodium alginate aqueous solution. This tendency is considered to have the advantage of enhancement injectability and pore saturation.

• Korea-Australia Rheology Journal
• /
• 제14권1호
• /
• pp.11-16
• /
• 2002

Cephalosporium acremonium is a filamentous microorganism producing cephalosporin C. The morphological differentiation of C. acremonium in submerged culture is closely related with the rheological properties of culture broth and production of cephalosporin C. In this study, the rheological and morphological properties of culture broth of C. acremonium were investigated. In the seed broths of shake-flask and fermenter culture, the Herschel-Berkley equation was in excellent agreement with experimental results in the whole range of shear rate. In the seed broths of shake-flask culture, morphological differentiation into arthrospores affected to changes of apparent viscosity. But results in the fermenter culture, morphological factors such as mean hyphal thickness and the number of tips gave more effect on changes of apparent vitacosity than differentiation into arthrospores. Overall, it suggested that the morphological parameters measured by image analysis can be used as a good parameter to indicate the rheological properties of culture broth of C. acremonium M25.

• Advances in concrete construction
• /
• 제9권1호
• /
• pp.93-102
• /
• 2020

In this study, we examined the relationship among the rheological properties, workability, and extrudability in the construction of concrete structures using additive manufacturing. We altered the component materials (binder type, water-binder (W/B) ratio, sand ratio) to assess their effect on the rheological properties experimentally. The results indicated that the W/B and sand ratios had the largest effect on the rheological properties. In particular, when the sand ratio increased, it indicated that adjusting the sand ratio would facilitate control over the rheological properties. Additionally, we compared the rheological properties with the results of a traditional workability evaluation, namely the table flow test. This indicated the possibility of inferring the rheological properties by using traditional methods. Finally, we evaluated extrusion quantity according to table flow. The extrusion rate was 350 g/s for a flow of 210 mm and 170 g/s for a flow of 130 mm, indicating that extrusion rate increased as flow increased; however, we concluded that a flow standard of approximately 140-160 mm is suitable for controlling the actual extrusion quantity and rate.

• 한국도로학회논문집
• /
• 제19권5호
• /
• pp.77-88
• /
• 2017

PURPOSES : It is necessary to clarify the rheological properties of cement paste as a basic research in the development of mechanistic concrete mix design. The rheological properties of cement paste with different binder types, mix propositions, and with/without high range water reducers have been analyzed. METHODS : In this study, ordinary Portland cement, fly-ash, blast furnace slag, silica fume, and limestone powder were used as binders. The range of water-binder ratio was 0.3-0.5, and a total of 30 different mixes have been tested. The slump flow test, V-funnel test, and Dynamic Shear Rheometer (DSR) test were performed to analyze the rheological properties of cement paste. RESULTS : As a result of the slump flow test, it was found that the composition ratio of the binder contents greatly affected the paste flow when the high range water reducers were added. The results of V-funnel test showed that when the water-binder ratio was decreased without high range water reducers, the binder composition ratio had a large effect on the passing time of the V-funnel tester, but with high range water reducers the impact of the binder composition ratio was decreased. The slump flow and V-funnel have a certain relationship with the rheological factors (yield stress and plastic viscosity), but the correlation was not significant. Finally, we proposed the M-value considering the density and specific surface area of the binder. The correlation between rheological factors and M-value were better demonstrated than experimental values, but there is still a limit to predict the rheological factor in general mix design. CONCLUSIONS :In this study, the rheological properties of cement paste were analyzed. The binder type, composition ratio of binder, and with/without high range water reducers have combined to provide the complex effects on the rheological properties of cement paste. The correlation between the proposed M-value and rheological factor was found to be better than experimental results, but needs to be improved in the future.

• Preventive Nutrition and Food Science
• /
• 제22권3호
• /
• pp.223-230
• /
• 2017

The purposes of this study were to produce polysaccharides from red pepper stems using different extraction methods and evaluate their chemical composition, in vitro biological capacities, and rheological properties. Two polysaccharides were extracted from red pepper stems using an autoclave and alkali treatments, and the extracts were named PAU and PAL, respectively. The contents of total phenolics and flavonoids were significantly higher in PAU than those in PAL. PAU exhibited greater scavenging activities on 2,2-diphenyl-1-picrylhydrazyl radicals, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radicals, superoxide radicals, and nitrite compared to PAL, suggesting that PAU served as better antioxidants. Similarly, in vitro inhibitory abilities against carbohydrate hydrolyzing enzymes of PAU were higher than those of PAL. Steady shear rheological analysis demonstrated that PAU showed higher psuedoplastic shear-thinning behavior compared to PAL. Based on the results from dynamic shear rheological properties, it was found that both samples had predominantly viscous behavior rather than elastic behavior.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1996년도 추계학술대회 논문집
• /
• pp.405-408
• /
• 1996

The rheological changes in sensitive materials was investigated by using QCA. Langmuir-Blodgett method was used to transfer sensitive material to the quartz crystals because of its facility to control the thickness. To develop gas sensor using quartz crystal, the rheological change of sensitive LB films were observed using the resonant resistance concept. And the rheological changes as to adsorption of organic vapours were used to analyze the response mechanism between organic vapours and sensitive LB films. We considered with resonant frequency of quartz crystal to obtain one-channel gas sensor and analytical tools of organic vapours response. In our results, we analyzed the organic vapours response by the rheological changes and mass loading as to adsorption of organic vapours.