• Journal of the Korean Ceramic Society
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• v.39 no.9
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• pp.871-877
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• 2002

Alumina slurriers, having various amount of alumina and ratio of organic additives, were prepared for tape casting. The relative viscosities were compared to investigate influence of composition on stability of the slurry and plotted as a function of powder fraction. They raised with increasing powder fraction of slurries, revealing a exponential function curve, which means that stability of slurry was not affected by amount and composition of organic additives. Cast green tapes were tested under tensile condition at room temperature. The increase in alumina ratio and binder ratio was found to decrease strain to failure of green tapes from 363% to 45% and from 68% to 25%, respectively. Tensile strength of green tapes increased abruptly with increasing alumina ratio, which showed its maximum at 1 MPa. On other hand, Tensile strength increased continuously from 0.5 MPa to 4 MPa with increasing binder ratio. Mechanical properties of them were affected seriously and lost their properties by elevating temperature from 20$^{\circ}C$ to 80$^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• v.29 no.8
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• pp.1554-1560
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• 2008

The probe diffusion and friction constants of methyl yellow (MY) in liquid n-alkanes of increasing chain length were calculated by equilibrium molecular dynamics (MD) simulations at temperatures of 318, 418, 518 and 618 K. Lennard-Jones particles with masses of 225 and 114 g/mol are modeled for MY. We observed that the diffusion constant of the probe molecule follows a power law dependence on the molecular weight of nalkanes, DMY${\sim}M^{-\gamma}$ well. As the molecular weight of n-alkanes increases, the exponent $\gamma$ shows sharp transitions near n-dotriacontane ($C_{32}$) for the large probe molecule (MY2) at low temperatures of 318 and 418 K. For the small probe molecule (MY1) $D_{MY1}$ in $C_{12}$ to C80 at all the temperatures are always larger than Dself of n-alkanes and longer chain n-alkanes offer a reduced friction relative to the shorter chain n-alkanes, but this reduction in the microscopic friction for MY1 is not large enough to cause a transition in the power law exponent in the log-log plot of DMY1 vs M of n-alkane. For the large probe molecule (MY2) at high temperatures, the situation is very similar to that for MY1. At low temperatures and at low molecular weights of n-alkanes, $D_{MY2}$ are smaller than $D_{self}$ of n-alkanes due to the relatively large molecular size of MY2, and MY2 experiences the full shear viscosity of the medium. As the molecular weight of n-alkane increases, $D_{self}$ of n-alkanes decreases much faster than $D_{MY2}$ and at the higher molecular weights of n-alkane, MY2 diffuses faster than the solvent fluctuations. Therefore there is a large reduction of friction in longer chains compared to the shorter chains, which enhances the diffusion of MY2. The calculated friction constants of MY1 and MY2 in liquid n-alkanes supported these observations. We deem that this is the origin of the so-called“solventoligomer”transition.

• Clean Technology
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• v.7 no.1
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• pp.65-74
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• 2001

Modified dip-coating method 8.3 times shorten in solution volume-coated and 83.3 times in coating time than existing dip-coating method. Coating weight increased nearly 2~3 times. So modified dip-coating method is evaluated that it is economic and has a efficiency. When we make an experiment in coated $LaCoO_3$ on ceramic monolith in modified dip-coating method which use 2 coating applications with relative viscosity $0.006202kg{\cdot}m/sec$, it showed a superior reaction at 88.56mg per ceramic unit gram in NO-CO reaction(optimum coating amount). When we make an experiment in the same size of ceramic filter cell with different conditions 100, 200cell per square inch, the result in low temperature($200^{\circ}C{\sim}350^{\circ}C$), 200cell3 per square inch is 6~23% higher in NO reduction and 11% in CO oxidation than 100cell per square inch. It is because the more the number of cells in the ceramic filter increase, the more catalytic surface area is expanded.

• Korean Journal of Food Science and Technology
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• v.24 no.4
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• pp.347-352
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• 1992

Physicochemical properties of native and defatted nonwaxy(Dongjin byeo) and waxy(Sinseunchalbyeo) rice starches were investigated. The granule shapes of rice starches were polygonal and X-ray diffraction patterns were A types, but relative crystallinity was decreased by defatting. The amylose content of defatted starches slightly increased, but water binding capacity of defatted starches decreased. Swelling power and solubility of starches increased with the increase of temperature, at each temperature increased by defatting. Transmittance of Dongjinbyeo and Sinseunchalbyeo starch suspensions showed a rapid increase at $60{\sim}65^{\circ}C$, $55{\sim}60^{\circ}C$ respectively. The initial pasting temperature by amylograph of Dongjinbyeo and Sinseunchalbyeo starches were $66^{\circ}C$ and $64^{\circ}C$, respectively. The gelatinization temperature of defatted starches was higher than that of the nondefatted starches. Dongjinbyeo starch decreased peak viscosity and breakdown by defatting, but Sinseunchalbyeo starch unchanged.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.1
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• pp.72-78
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• 2008

In this study, advanced (fluid-structure interaction (FSI)) analysis system has been developed in order to predict turbine cascade performance with blade deformation effect due to aerodynamic loads. Intereference effects due to the relative movement of the rotor cascade with respect to the stator cascade are also considered. Reynolds-averaged Navier-Stokes equations with one equation Spalart-Allmaras and two-equation k-ω SST turbulence models are solved to accurately predict fluid dynamic loads considering flow separation effects. A fully implicit time marching scheme based on the (coupled Newmark time-integration method) with high artificial damping is efficiently used to compute the complex fluid-structure interaction problem. Predicted aerodynamic performance considering structural deformation effect of the blade shows somewhat different results compared to the case of rigid blade model. Cascade performance evaluations for different elastic axis positions are importantly presented and its aeroelastic effects are investigated.

• Journal of Korean society of Dental Hygiene
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• v.11 no.1
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• pp.113-126
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• 2011

Objectives : We supposed that identifying the influencing factors on DMFT index in the primary school children in Pocheon be indispensible for the primary school children's oral health program establishment in Pocheon. So, to prepare the basic materials for the primary school children's oral health program establishment in Pocheon, we analyzed the associated factors which could have an influence on the primary school children's DMFT index in Pocheon. Methods : We selected 3,676 primary school children in Pocheon, whose age were from 6 to 11, and surveyed those children by a questionnaire and the oral examination based on WHO's oral health survey method. Data were analyzed with a $x^2$-test and multiple regression analysis using SPSS $15.0^{(R)}$. Results : The results of oral survey in the primary school children in Pocheon revealed as follows: DMFT index, National Health Oral health survey of 2006 people nationwide in the results when compared to younger grade children and older grade in the low and the higher. Subjective oral health awareness, high of viscosity junk food snacks, fruit, gender, dental visits and humidity, oral health education classes, including the variable of attitude was 6(p<0.05). Their higher awareness of dental health, oral health education classes ever the more positive attitude to DMFT index was statistically significant(p<0.05). Solid in the habit of eating junk food snacks to the students of a liquid relative to student intake was higher DMFT index indices(p<0.05). Conclusions : We could reason that one's oral health recognition and behavior should have a relationship with his(her) DMFT index.

• Advances in Energy Research
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• v.4 no.1
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• pp.69-86
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• 2016

The quest to reduce the level of overdependence on fossil fuel product and to provide all required information on proven existing alternatives for renewable energy has resulted into rapid growth of research globally to identify efficient alternative renewable energy sources and the process technologies that are sustainable and environmentally friendly. The present study is aimed at production and characterization of bioethanol produced from sugarcane juice using a $2^4$ factorial design investigating the effect of four parameters (reaction temperature, time, concentration of bacteria used and amount of substrate). The optimum bioethanol yield of 19.3% was achieved at a reaction temperature of $30^{\circ}C$, time of 72 hours, yeast concentration of 2 g and 300 g concentration of substrate (sugarcane juice). The result of statistical analysis of variance shows that the concentration of yeast had the highest effect of 7.325 and % contribution of 82.72% while the substrate concentration had the lowest effect and % contribution of -0.25 and 0.096% respectively. The bioethanol produced was then characterized for some fuel properties such as flash point, specific gravity, cloud point, pour point, sulphur content, acidity, density and kinematic viscosity. The results of bioethanol characterization conform to American society for testing and materials (ASTM) standard. Hence, sugarcane juice is a good and sustainable feedstock for bioethanol production in Nigeria owing relative abundance, cheap source of supply and available land for large scale production.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.25 no.4 s.34
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• pp.123-131
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• 1999

Liquid crystal known as a rheological barrier to coalescence of oil droplets, increases emulsion stability, water-holding capacity and promotes active material penetration to skin. Some investigation for its rheological characteristics have been reported but its relations to consumer perception have been rarely published. In this study, oil/water emulsion and oil/liquid crystal/water systems were manufactured using the same composition or Behenyltrimethylammonium chloride/Cetostearyl alcohol/Lanolin oil. and rheological properties or each system were investigated with Cone and Plate rheometer. The formation of liquid crystalline phase was observed with polarized microscope and Differential Scanning Calorimeter. Continuous shear experiment, creep, yield and water holding capacity were measured for oil/water and oil/liquid crystal/water systems. The results were compared with sensory evaluations. Oil/liquid crystal/water system showed higher,viscosity at the same shear rate. higher viscoelasticity and higher yield stress than oil/water system. These properties were expected to show good spreadability and excellent richness without waxiness in hair can: products of creme type. This expectation was consistent with the results of sensory experiments. Water-holding capacity was evaluated by measuring residual water of specimens at specific temperature and relative humidity. Oil/liquid crystal/water system was proved to have higher ability to hold water in comparison with oil/water system. The results indicated that oil/liquid crystal/water system was of benefit to rheological properties creme type hair care products.

• Polymer(Korea)
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• v.24 no.6
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• pp.820-828
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• 2000

In this study, biaxially oriented film process was used to improve barrier property of polypropylene (PP)/ethylene-vinyl alcohol copolymer (EVOH) blends by inducing a laminar morphology of the dispersed phase in the matrix phase. In order to examine the extent of deformation during melt extrusion process, the rheological properties of the resins were measured and the viscosity ratio of the dispersed phase to the continuous phase was determined. The effects of compatibilizer content, draw ratio, and draw temperature on the oxygen permeability and morphology of biaxially drawn blend films were studied. The laminar morphology of the EVOH phase with a larger area of thinner layer induced by biaxial orientation was found to result in a significant increase in oxygen barrier property of PP/EVOH (85/15) blends by about 10 times relative to the pure PP When both PP-g-MAH and ionomer were used as the compatibilizers, there existed an optimum level of compatibilizer content for obtaining improved barrier properties with a well developed laminar structure. In addition, higher draw ratio and draw temperature were found to be more favorable processing conditions in obtaining higher barrier blends.

• Food Science of Animal Resources
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• v.38 no.3
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• pp.451-467
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• 2018

Hot pepper has anti-obesity effects by controlling appetite and reducing blood fat level. To reduce the pungency of capsaicin, red or green hot pepper juice was fermented with Bacillus licheniformis SK1230. Fermented hot pepper juice was then added into yogurt at different ratios. The pH of yogurt added with hot pepper juice was decreased from 4.61 to 4.48. Titratable acidity and counts of lactic acid bacteria were increased with increasing amount of pepper juice added. However, the viscosity was decreased significantly compared to the control. On chromaticity test, when more pepper juice was added, $L^*-value$ was decreased whereas $a^*$- and $b^*$- values were increased significantly (p<0.05). The spectrum of antimicrobial activity of yogurt was slightly changed compared to using pepper juice. Total polyphenol contents and antioxidant activity were increased with increasing amount of pepper juice added. Stirred yogurt added with fermented red pepper juice at 3% or green pepper juice at 1% showed high scores in flavor, appearance, texture, and overall acceptance in sensory test. Yogurt added with fermented pepper juice with reduced pungency showed also good palatability during storage at $4^{\circ}C$. Yogurt with added hot pepper juice can be play an important role in functional food relative to anti-obesity.