• Proceedings of the Korea Association of Crystal Growth Conference
• /
• 1996.06b
• /
• pp.129-153
• /
• 1996

In aqueous slurry processing of silicon nitride, the interaction of dispersant and binder on the surface of particles was studied to identify the effect of these additives on ceramic powder processing. Polymethacrylic acid (PMAA) and polyvinyl alcohol (PVA) were used as dispersant and binder, respectively. the adsorption isotherms of PMAA and PVA for the silicon nitride suspension were determined, while the adsorption of PMAA was differentiated in the mixed additive system by ultraviolet spectroscopy. These experiments were done in order to investigate the effect of these organic additives on the physicochemical properties of silicon nitride suspensions. The electrokinetic behavior of silicon nitride was subsequently measured by electrokinetic sonic amplitude (ESA). As PMAA adsorbed onto silicon nitride, the isoelectric point (pHicp) shifted from pH=6.7 to acidic pH, depending on the surface coverage of PMAA. However, adsorption of PVA did not change the pHicp of suspensions, but did decrease the surface potential of silicon nitride moderately. The rheological behavior of silicon nitride suspensions was measured to assess the stability of particles in aqueous media, and was correlated with the electrokinetic behavior and adsorption isotherm data for silicon nitride.

• Journal of the Korean Ceramic Society
• /
• v.44 no.1 s.296
• /
• pp.6-11
• /
• 2007

The rheological properties of slag cement pastes by effect of particle size distribution of binder were investigated using a Rheostress 1 rheometer (Haake) with a cylindrical spindle and the relationship between fluidity particle size distribution using the Rosin-Rammler equation. Samples are combined the two types of slag powder and OPC, fine slag particles sized Elaine specific surface area $8,000cm^2/g$, coarse slag particles sized Elaine specific surface area $2,000cm^2/g$, intermediate OPC particles $3,450cm^2/g$, used to search for the combination that would yield the best quality product. The all flow curves which were measured by rheometer showed hysterisis and could be classified into 4 types. When the combination was based on a ratio of 15-20 vol% fine particles, 40-50 vol% intermediate particles, 30-40 vol% coarse particles of the total volume, a high fluidity and low yield-strength was achieved. The Rosin-Rammler function can explain aboved correlation flow curve types. On type 1, the n-value had a correlation with plastic viscosity however the blend of type 2 and 3 showed consistent n-value regardless of plastic viscosity. In addition, the blend in type 4 tended to a rise in fluidity according to the increase of the n-value.

• Food Science of Animal Resources
• /
• v.38 no.3
• /
• pp.476-486
• /
• 2018

In this study, the droplet size distribution, rheological properties, and stability of dairy cream-based emulsions homogenized with different sucrose fatty acid ester (SFAE, a non-ionic small-molecule emulsifier) concentrations (0.08%, 0.16%, and 0.24% w/w) at different homogenization pressures (10 MPa and 20 MPa) were examined. Homogenization at a high pressure resulted in a smaller droplet size and narrower droplet size distribution. The D[4,3] (volume-weighted mean) and D[3,2] (surface-weighted mean) values of the emulsions decreased with an increase in the SFAE concentration. The flow properties of the emulsions homogenized with SFAE showed shear-thinning (n=0.21-0.46) behavior. The apparent viscosity (${\eta}_{a,10}$) and consistency index (K) of the homogenized emulsions were lower than those of the control sample that is non-homogenized and without SFAE, and decreased with an increase in SFAE concentration. The storage modulus (G') and loss modulus (G") of all emulsions homogenized with SFAE were also lower than those of the control sample. The stability of all emulsions with SFAE did not show any significant change for 30 d at $5^{\circ}C$. However, the emulsions stored at $40^{\circ}C$ were unstable over the storage period. Therefore, the addition of SFAE enhanced the stability of dairy cream emulsions during storage at refrigeration temperature ($5^{\circ}C$).

• Korean journal of food and cookery science
• /
• v.23 no.4 s.100
• /
• pp.481-491
• /
• 2007

This study was conducted to develop pizza crust with additions of Chungkukjang and onion. The stickiness of the pizza dough containing fresh Chungkukjang (C), heated Chungkukjang (HC), and fresh Chungkukjang with added dough-improver (CI), was measured to evaluate the dough properties. The optimum conditions for pizza crust preparation relating to the processing suitability and sensory quality were established using response surface methodology (RSM). When HC and CI were used in dough making, dough stickiness was reduced to 37% and 51%, respectively. Therefore, the dough-improver(2%) offered the pizza dough better rheological properties when C was used without heat treatment. On the other hand, processing suitability such as the spreadability and overall acceptability, which included the smell and taste of the pizza, were impaired as the amount of CI increased. However, the use of fresh ground onion in the pizza dough compensated for these impairments. The optimum conditions for pizza crust making as determined by RSM were 25.1% onion, 7.1% Chungkukjang, and 52.3 min of fermentation time.

• Korean journal of food and cookery science
• /
• v.19 no.4
• /
• pp.429-438
• /
• 2003

The optimization of Omija-pyun as a traditional dessert, with the most European taste and year round availability, was studied with regard to its texture. The response surface methodology was used to determine the optimal composition of Omija-pyun as a European style dessert. The texture, including the springiness, gumminess, cohesiveness, adhesiveness, hardness and chewiness, was measured using TPA parameters (TA-HD Texture Analyser, stable micro system, UK). The texture of Omija-pyun was influenced by pectin and sucrose to the first linear order. The properties of springiness and adhesiveness were influenced by pectin x pectin to the second quadratic order. No cross product effects between ingredients were found from the analysis. The maximum springiness was obtained with 42g of pectin, 450g of sucrose, 110g of glucose syrup and 4.8g of tartaric acid. The maximum chewiness was with 55g of pectin, 330g of sucrose, 140g of glucose syrup and 5.7g of tartaric acid. The maximum adhesiveness was achieved using 17g of pectin and 400g of sucrose. The gumminess and hardness increased with increasing pectin content, and a cross product effect was observed(Eds note: you said earlier that no cross product effects between the ingredients was found\ulcorner) between sucrose and glucose syrup.

• Elastomers and Composites
• /
• v.34 no.5
• /
• pp.407-413
• /
• 1999

Non-ceramic composite insulator has been interested in the power industry because of its good characteristics in mechanical properties, mass product and design availability. Also it is lighter, and less unexplosive, compared to a ceramic insulator. Especially EPDM rubber composite insulator can be used for long-term in contaminated environments because of its hydrophobicity. This paper showed the rheological properties, the electrical properties, and contact angles to check the hydrophobicity and the recoverability of the EPDM compounds. Also, we investigated surface morphology of the compound by SEM.

• Elastomers and Composites
• /
• v.41 no.2
• /
• pp.97-107
• /
• 2006

The recycled polyethylene composites with various ratio of ground waste tire powder were manufactured by using a fully intermeshing co-rotating twin screw extruder for the reuse of waste tire scrap. In this investigation, the ground waste tire powders (GWTP) were blended with virgin HDPE and recycled polyethylene in the weight ratio of 0 to 50 wt.%. Mechanical properties such as tensile strength, elongation at break and impact strength were measured by using ASTM standard. The experimental results for the various composite showed that the tensile strength of composites decreased with increasing GWTP ratio, while elongation at break increased with the amounts of GWTP. On the other hand, the impact strength for the three kinds of composites showed maximum at the 30 wt.% of GWTP and then decreased. Morphology of the fracture surface tends to be rough with increasing waste tire powder content. Rheological properties were investigated by measuring the shear viscosity against shear rates and softening temperatures. They showed that melt viscosity of rubber composites in this study subsequently increased with increasing GWTP content as a result of increase of flow resistance against external stress and followed a Power-law behavior.

• Food Science and Preservation
• /
• v.19 no.6
• /
• pp.841-848
• /
• 2012

Response surface methodology was applied to the processing conditions to investigate the physicochemical properties of ramie porridge. In the processing conditions based on the central composite design with the addition of ramie leaf powder (0-4 g) and water (700-1100 g), the coefficients of determination (R2) of the models were above 0.9141 for the physicochemical properties, above 0.7627 for the Hunter color parameters, and above 0.8975 for the rheological properties. The soluble solid content, viscosity, and gumminess of the sample decreased significantly with an increase in the water added, whereas the spreadability and adhesiveness increased significantly. The Hunter color L value of the sample decreased significantly with an increase in the amount of ramie leaf powder added, whereas the Hunter b value increased significantly. The estimated maximum viscosity of the ramie porridge was shown to be 24,643 cp when 1.90 g ramie leaf powder and 700.24 g water were added; the estimated maximum lightness of the ramie porridge was shown to be 59.11 when 0.02 g ramie leaf powder and 869.30 g water were added; and the estimated maximum gumminess of the ramie porridge was shown to be 21.46 g when 2.12 g ramie leaf powder and 700.35 g water were added.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.23 no.2
• /
• pp.1-14
• /
• 2005

Generally, printing inks are composed of pigment, vehicle and additive. Among others, the vehicle transfers the pigment to substrate and then binds it on the surface. So, rheological properties of the vehicle are an important factor which has influence on printability. Thus, in this study, rheology of the vehicle was investigated by using rotational rheometer according to molecular weight of resin. Also, emlusion rheology of water in oil type and its microstructure were examined with increasing the shear rate. Consequently, the following results were obtained: (1) By viscometric flow test, zero shear viscosity and shear thinning index of vehicle increased with increasing the molecular weight of resin. (2) By relaxation and creep test, relaxation time and retardation time of vehicle increased with increasing the molecular weight of resin. (3) By frequency sweep test, crossover point of vehicle increased with increasing the molecular weight of resin. (4) G' and G" of emlusions increased with increasing the molecular weight by amplitude sweep test. (5) The shape of water drop in emlusions was changed to the capillary tube.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.19 no.1
• /
• pp.28-41
• /
• 2001

Rheological properties of ink and Ink-Water balance are the important factors in lithographic printing. Laboratory test method which determines the emulsification rate of dampening solution and ink has been described. The emulsification theory and laboratory test method deduced from Surland and it has become a useful tool for the industry. The effects of pH value and surface tension of dampening solution on the emulsification rate has been tested by many researcher. In this paper we focused on the factors which influence in the emulsification such as pH and surface tension of dampening solution and emulsifying temperature. To study on the factors determining the emulsion velocity, we have measured water pickup and calculated emulsion velocity constant 'k' and activation energy.