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.

White rice with grains is a nutritious meal that richly contains fiber, vitamin and mineral, but it is difficult for elderly people to masticate some grains and beans due to its hardness. This study was aimed to find the optimal mixing ratio of rice with texture modified grains and beans by comparing rheological properties. Beans were soaked in tap water for 24 hr at 20°C, cooked under pressure (1hr at 121°C), frozen for 24 hr at -18°C, and thawed in water bath for three hr at 30°C. The samples were submerged in macerating enzyme solution, left under vacuum at 60 mmHg for 5 min to infuse the enzyme into the intercellular spaces of samples, and rapidly returned to the atmospheric pressure. The samples were removed from enzyme solution, sealed in plastic bag, placed at 70°C for 20 min for enzyme activation and inactivated at 95°C for 15 min. The grains and texture modified beans were added to white rice with different ratio, soaked for one hr in enzyme solution under warming condition at 70°C, and steamed with electric pressure cooker. Cooked meals were rapidly cooled at -18°C for one hr, placed at 20°C for another one hr, and then rheological properties were measured with texture analyzer. The hardness of texture modified rice with grains was reduced to 2.3 ~ 4.1 × 104 N/m2 and the hardness of rice with beans was reduced to 3.8 ~ 4.8 × 104 N/m2 depending on mixing ratio. The cohesiveness was reduced by 1/3 ~ 2/3 respectively, while adhesiveness was not changed significantly, compared to those of cooked rice. These results suggest that cooked rice mixed with 30 ~ 40% of grain and 6 ~ 10% of bean would be appropriate for elderly people to consume without chewing difficulty.

The blending schemes of Saengshik powder with water were established to retain the dispersion stability of the Saengshik beverage in order to develop a ready-to-drink type product. The effect of the blending on the rheological properties and the dispersion stability of Saengshik beverage were determined. The Saengshik beverages, blended with low shear force for a short time, showed dilatant fluid characteristics, while those with high shear force for a long time had pseudoplastic fluid ones. The consistency of Saengshik beverage increased with the blending speed and time. Saengshik beverage blended at low shear showed rheopexy while becoming time independent by a highshear blending action. A logarithmic model fitted well to the changes in backscattering light flux with the rest time of Saengshik beverage. Based on sedimentation kinetics, the migration speed of clear front, and the thickness of sedimented layer, Saengshik beverage with maximum dispersion stability was obtained by a high shear blending at 15,120 rpm for 25 s.

Silk fibroin (SF) and silk sericin (SS) have been studied as a biomaterial due their useful properties including good blood compatibility and good cell activities. However, previous studies, silkworm variety has not been considered although it can affect structure and properties of silk fibroin and sericin. Therefore, in the present study, structure and properties of silk fibroins and sericins obtained from different silkworm variety were examined. Most of regenerated SF solutions from different silkworm varieties displayed Newtonian fluid behaviors and their viscosities were different depending on the silkworm variety. N74 showed the highest viscosity among the SF samples. Molecular weight (MW) distribution and mechanical properties of regenerated SF showed similar result to viscosity result. SS did not show significant difference in MW distribution and viscosity result depending on the silkworm variety.

본 연구는 혈압 강하, 비타민 B1의 활성화, 항암 효과, 노화방지 등에 탁월한 효과가 있다고 알려진 마늘의 활용도를 더욱 높이기 위하여 중력분에 수준별(1%, 3%, 5%) 마늘 분말을 첨가하여 물성 변화 및 마늘가루 첨가가 제면 적성에 미치는 영향을 실험하였다. 마늘 분말 첨가량을 달리하였을 때 호화도 변화를 측정한 결과, 마늘 분말 양이 증가하면 호화 개시온도가 높아졌으며, 최고 점도는 낮아졌다. 최고 점도와 최저 점도의 차이를 나타내는 breakdown 값도 낮아졌다. 또한 최종 점도도 약간 낮아지는 경향을 보였으며, 마늘 분말 첨가량이 증가하면 set back값은 감소하는 경향이었지만 노화를 억제할 정도는 아니었다. Farinogram의 consistency는 마늘 분말 첨가량이 많아질수록 높아졌고, 수분흡수율 또한 높아지는 경향을 보였다. 반죽형성시간은 길어졌으며 안정도는 낮아졌으며, 마늘 분말 첨가량이 많아질수록 time to breakdown 값이 급격하게 떨어졌다. Mechanical tolerance index 값이 마늘 분말 첨가 시료들의 경우 낮게 나타나, 마늘 분말을 첨가하면 반죽의 기계적 적성이 떨어진다는 것을 알 수 있었다. Farinogram quality number는 중력분 대조구에 비하여 마늘 분말 첨가구들은 첨가량이 많아질수록 그 수치가 떨어졌다. 그러나 1% 첨가구와 3% 첨가구 사이에서는 서로 간에 유의적인 차이를 보이지 않았다. Alveogram을 이용하여 글루텐 강도를 측정한 Pmax 값은 마늘분말 첨가량이 많아질수록 Pmax 값이 감소되었을 뿐만 아니라, 서로 간에 유의적인 차이를 보이지도 않았다. 팽창된 반죽이 터질 때까지의 신장성을 나타내는 L값은 마늘 분말 첨가량이 증가하면 감소하였다. 그러나 3% 첨가구와 5% 첨가구 사이에서 유의적인 차이는 나타나지 않았다. 팽창지표를 나타내는 G값 역시 마늘 분말 함량이 많아지면 G값은 낮아졌다. 하지만 3% 첨가구와 5% 첨가구 사이에서는 L값과 마찬가지로 유의적인 차이를 보이지 않았다. 변형 에너지 값인 W값도 마늘 분말 첨가량이 증가하면 W값은 감소하였으며, 특히 대조구에 비하여 마늘 분말 1% 첨가구는 급격하게 수치가 낮아졌다. 3% 첨가구와 5% 첨가구 사이에서는 유의적인 차이를 보이지 않았다.

Polyacrylonitrile (PAN) copolymers of different molecular weights were synthesized by a suspension polymerization and precipitation polymerization method. The rheology behaviors of the synthesized PAN copolymers were investigated in relation to their molecular weight, solid content and melting temperature. The influence of "historical effects" on the spinning solution of PAN was studied by analyzing the laws of viscosity considering the diversification time and temperature. The viscosity disciplines of each spinning solution conformed well to the rheological universal laws in a comparison of the suspension polymerization product with that of precipitation polymerization. Viscosity changes in the swelling process of dissolution were gentler in the suspension polymerization product; a small amount of water will quickly debase the solution viscosity, and high-speed mixing can greatly shorten the time required by the spinning solution to reach the final viscosity.

Cheese is regarded as a viscoelastic food material. Textural properties of cheese play an important role in overall quality and consumer preference. Textural properties of cheese can be analyzed by rheological analysis and sensory evaluation analysis. Instrumental mechanical methods can provide the measurement of rheological properties of cheeses affecting physical properties, such as cracks, firmness, fracture, and production of eyes in cheeses. Descriptive sensory analysis with well-defined sensory descriptive words is a powerful tool to identify and quantify the key sensory properties of cheeses. In this article, major analytical methods to determine the rheological and sensory properties of cheeses and their applications to cheeses are presented.

In this study, the rheological properties of doughs blended with 5% to 20% fermented rice bran (FRB) were investigated using farinographs, amylographs, extensographs, and SEM. In the farinograph analysis, the water absorption decreased and the replacement ratio of FRB increased over the time of development of the dough. The stability time of the dough was shortened, and the degree of softening decreased with added volume of FRB. The amylograph analysis showed that the temperature at the beginning of gelatinization showed a tendency to increase with increasing replacement ratio of FRB, but the gelatinization temperature showed no significant difference between the FRB-added groups and control group. The extensograph analysis showed that when the replacement ratio of FRB was over 10%, the extension of the dough decreased while the resistance was increased. In the SEM analysis, the added dough with less than 10% FRB had similar characteristics in gluten matrix and gas bubbles to those of the control of wheat flour alone. It was concluded that an added FRB volume of below 10% is most suitable for bread making.

There are several methods determining an appropriate performance grade of virgin binder, which is re(erred as design binder, in RAP contained bituminous mixture design process. However, difficulties have been experienced in utilizing the methods in the field application in Korea, because SHRP binder test, the key tests to determine a design binder, requires well-trained personnel, high price equipment, and time consuming process. Thus, the study investigated the relationship among the binder aging level, RAP contents, and rheologica1 properties of binder. The study results provide mix designer with a simple method in selecting an appropriate grade of virgin binder.

This study aims to investigate the quality characteristics of breads with the addition of sweet pumpkin powder. Farinogram showed that the absorption rate of the dough decreased, the development time and stability became shortened, and the degree of attenuation tended to be grown along with increasing the amount of pumpkin powder. From the amylogram, it was found that the gelatinization starting temperature and the maximum viscosity of pumpkin powder added dough seemed to be decreased as the amount of pumpkin powder was increased. Extensogram showed that there was a decrease in the degree of extension of the dough added with increasing the amount of pumpkin powder, while an increase in the degree of resistance and resistance/extensibility. The lightness (L value) and redness (a value) of bread was found to be decreased with increasing the amount of pumpkin powder, while the yellowness (b value) increased. In terms of the dough texture, for which the hardness, cohesiveness and gumminess of the dough were measured, there were no significant differences between groups, while the dough added with 8.0% pumpkin powder showed a significant decrease in the elasticity. The results of sensory evaluation showed that the highest score of color (p<0.05) and taste (p<0.05) were obtained from the bread added with 6.0% and 8.0% pumpkin powder, while the highest score of texture in control and 3.0% pumpkin bread. In addition, the highest score of flavor (p<0.05) and overall acceptance (p<0.05) were observed in bread added with 6.0% pumpkin powder. Upon the results of this study, it was assumed that the development of food products using pumpkin are prospective in response to health-oriented consumers.

In this paper, rheological characteristics of Metal Injection Moulding (MIM) feedstock using locally binder of palm stearin are presented. The feedstock consisted of 316L-grade stainless steel powder with three different particle sizes and the binders comprise palm stearin and polyethylene. The viscosity of MIM feedstock at different temperatures and shear rates was measured and evaluated. Results showed that, the feedstock containing palm stearin exhibited suitable rheological properties and suitable to produce a homogeneous feedstock that is favorable for injection molding process.

바인더의 노화로 인한 성능변화는 침입도 또는 점도시험을 실시하여 판정하여왔다. 기존의 시험방법으로 아스팔트 바인더의 점탄성 특성과 실제거동을 평가할 수 없기 때문에 새로운 분석방법이 요구되어 왔다. 본 연구에서는 기존시험 방법을 사용하여 침입도지수와 잔류침입도를 판정하였고, 양방향 반복회전 모드와 일방향 반복회전 모드 시험을 실시하여 단기 노화된 아스팔트 바인더의 유변학적 특성을 분석하였다. 시험결과 단기 노화된 아스팔트 바인더는 시험주기(frequency) 즉, 차량속도의 변화에 따라 서로 다른 복합계수와 위상각을 나타냈으며 단기 노화 전후의 크리프 컴플라이언스 및 전단점도 시험결과에도 영향을 미치는 것으로 나타나서 포장 설계시 이러한 특성이 고려되어야 한다.

To investigate the effect of sourdough on the characteristics of quality of barley bread, sourdough starter with Lactobacillus plantarum, Lactobacillus sanfrancisco and Enterococcus sp. were added to baking after 48 hours incubation at 37℃. 1. The pH of bread using Lactobacillus sanfrancisco starter was the lowest among tested starters. while the titratable acidity(TTA) of the strain was the highest, followed by Enterococcus sp.. 2. In bread, moisture contents of control were 38%. It was decreased during 6 days. The moisture contents of bread using Lactobacillus sanfrancisco starter were the highest among tested starters, followed by Enterococcus sp.. 3. Oneset temperature(To), peak temperature(Tp) and enthalphy (δH) were increased during storage of 6 days. The enthalphy of bread using Lactobacillus sanfrancisco starter was the lowest among tested starters, followed by Enterococcus sp..

A Lactic acid bacterium for barley bread was isolated from barley powder and was identified as Enterococcus sp. It was used as a starter for barley bread and quality of bread was compared with the bread prepared by conventional starter 1. The pH of bread making process using Lactobacillus sanfrancisco starter was the lowest among tested starters. while the titratable acidity(TTA) of the strain was the highest, followed by Enterococcus sp.. 2. In valorimeter value(v/v), control was 70, but dough using all starter was 60. The peak time and stability of dough using Lactobacillus sanfrancisco were the highest among tested starters. 3. Extensibility of dough using Enterococcus sp. was the highest among tested starters, followed by Lactobacillus sanfrancisco. Proper extensibility and maximum resistance were observed in Lactobacillus sanfrancisco.