• Journal of Food Hygiene and Safety
• /
• v.5 no.1
• /
• pp.27-34
• /
• 1990

As a link in the studies on the extracellular polysaccharide by lactic acid bacteria, the experiment was conducted to investigate the viscosity variations of 10% reconstituted skim milk and optimum cultural conditions for the production of extracellular polysaccharide. 1. The viscosity of 10% reconstituted skim milk cultured by 8tr. thermophilu8 510 reached 5,000 CP at $41^{\circ}C$ and on 5 days. Because it was the highest value among the microorganisms tested, Str. thermophilu8 510 was chosen as a main test microoganism and studied on factors affecting maximum viscosity depending upon production of exopolysaccharide. 2. Absorbance of synthetic culture medium was highest at $41^{\circ}C$. Sucrose, in a member of carbohydrates, was the most effective carbon source for the production of exopolysaccharide within 5% concentration. 3. The production of exopplysaccharide was stimulated by $Mg^{++}$.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.3
• /
• pp.146-153
• /
• 2011

American NREL (National Renewable Energy Laboratory) reported that BDF20 could reduce PM, CO, SOx, and cancerogenic matters by 13.6%, 9.3%, 17.6%, and 13% respectively, compared to diesel fuel. BDF20 has been being tested on garbage trucks and official vehicles at Seoul City, which is positive on air environment, but negative on combustion by higher viscosity in winter season. This study investigated the combustion characteristics by applying pilot injection for improving the deterioration of combustibility caused by the higher viscosity of the BDF20 with the combustion flames taken by a high-speed camera and the cylinder pressure diagram. A 4-cycle single-cylinder diesel engine was remodeled to a visible 2-cycle engine taking the flame photographs, which has a common-rail injection system. The test was done laboratory temperature at $5{\sim}6^{\circ}C$. The results obtained are summarized as follows, (1) In the case of without pilot injection, the flame propagation speed was slowed and the maximum combustion pressure became lower. The phenomena became further aggravated as the fuel viscosity gets higher. (2) In the case of with pilot injection, early stage of combustion such as rapid ignition timing and flame propagation was activated since intermediate products formed by pilot injection act as a catalyst for combustion of main fuel.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.17 no.1
• /
• pp.105-113
• /
• 2009

The performance of a direct-injection type diesel engine often depends on the strength of swirl or squish, shape of combustion chamber, the number of nozzle holes, etc. This is of course because the combustion in the cylinder was affected by the mixture formation process. In this paper, combustion process of biodiesel fuel was studied by employing the piston which has several grooves with inclined plane on the piston crown to generate swirl during the compression stroke in the cylinder in order to improve the atomization of high viscosity fuel such as biodiesel fuel and toroidal type piston generally used in high speed diesel engine. To take a photograph of flame, single cylinder, four stroke diesel engine was remodeled into two stroke visible engine and high speed video camera was used. The results obtained are summarized as follows; (1) In the case of toroidal piston, when biodiesel fuel was supplied to plunger type injection system which has very low injection pressure as compared with common-rail injection system, the flame propagation speed was slowed and the maximum combustion pressure became lower. These phenomena became further aggravated as the fuel viscosity gets higher. (2) In the case of swirl groove piston, early stage of combustion such as rapid ignition timing and flame propagation was activated by intensifying the air flow in the cylinder. (3) Combustion process of biodiesel fuel was improved by the reason mentioned in paragraph (2) above. Consequently, the swirl grooves would also function to improve the combustion of high viscosity fuel.

• Journal of the Korean Magnetics Society
• /
• v.4 no.4
• /
• pp.326-334
• /
• 1994

This paper describes the fabrication of the hydrophilic magnetic fluid with high viscosity and its application to oil seal apparatus used with the Nd-permanent magnet. The results are as follows. 1) The ultrafine magnetite particles under the size of $100\;{\AA}$ are first coated by the oleic acid ion and again adsorbed by the hydrophilic D. B. S. ion, and there by hydrophilic magnetic fluid with high viscosity could be made by dispersing them into the ethylene glycol. 2) In development of the oil seal apparatus using magnetic fluid and Nd-permanent magnet, the viscosity and magnetic susceptibility show high when the $Fe_{3}O_{4}$ content is over 50%(g/cc) in the fluid, so that such properties could improve highly the capability of oil seal. 3) The maximum of the resisting pressure of the oil seal using the ethylene glycol base magnetic fluid and the Nd-permanent magnet, is about $50\;g/\textrm{cm}^2$, under the condition of this experiment. Therefore the oil seal may not be suitable for the ship engine and the driving part of the automobile, and thus it needs a lot further complementary reserch. However, it is quite favourable for such an oil seal apparatus as speed reducer under the condition of atmospheric pressure.

• Korean Journal of Food Science and Technology
• /
• v.28 no.3
• /
• pp.514-520
• /
• 1996

The purpose of this study was to develop the production technology of modified starch. Corn starches were gamma irradiated at 0-110 kGy and the effect of irradiation dose levels on the physicochemical properties of corn starches were investigated. Blue value linearly decreased, while alkali number and solubility markedly increased as irradiation dose levels were increased. The optical transmittance increased as applied irradiation dose levels were increased in the temperature range of $65-95^{\circ}C.$ Water binding capacity and swelling power showed maximum value at 30 and 10 kGy, respectively and they tended to decrease thereafter. Gelatinization viscosity of the gamma irradiated starch considerably decreased as compared to that of the non-irradiated starch. Irradiation at 110kGy resulted in a marked reduction of peak viscosity and cooling viscosity at $30^{\circ}C$ by 100 and 300 times, respectively. The physicochemical properties of corn starch irradiated at 30 kGy were similar to those of commercial acid-modified starch, while those of corn starch irradiated at 100 kGy were similar to those if oxidized starch.

• Korean Journal of Food Science and Technology
• /
• v.18 no.3
• /
• pp.192-196
• /
• 1986

Cold gelatinization of two naked burley (Songhak and Youngsan) starches in NaOH (0.14-0.21N) and KSC N (1.5-4.5M) was compared. Light transmittance of starch suspension in aqueous NaOH solution was higher in Youngsan starch than in Songhak starch. Viscosity of Youngsan starch was also higher at various starch concentrations (5-12.5%), however the critical concentration of NaOH for the gelatinization of Youngsan starch was lower by 0.1meq NaOH/g starch compared to Songhak starch. Two starches held a linear relationship between viscosity development rate and alkali concentration at a fixed starch concentration. The viscosity development rate of the starch was linearly decreased as starch concentration increased at a fixed alkali concentration. Gel volume of the starches was attained maximum at 2.5M KSCN, however Youngsan starch showed a higher volume and a less stability in KSCN than Songhak starch.

• Journal of the East Asian Society of Dietary Life
• /
• v.17 no.3
• /
• pp.371-378
• /
• 2007

Red ginseng has been considered a functional food, and many studies on red ginseng and the prevention of cancer, hypertension, arteriosclerosis and constipation have been conducted. In this study, white bread dough with 1, 2, 3, 4 or 5% red ginseng marc powder was measured by a farinograph, extensograph, amylograph, as well as for pH to evaluate the development time, stability, extensibility, resistance to extension, gelatinization temperature, and maximum viscosity temperature. The ash content of the wheat flour increased with an increasing content of red ginseng marc powder. The gelatinization maximum and the temperature for the gelatinization maximum of the flour-water suspension in the amylograph were not affected by the addition of red ginseng marc powder. The moisture absorption of the wheat flour in the farinograph increased as the content of red ginseng marc powder increased. Also, as the content of red ginseng marc powder increased, dough development time decreased. The extensibility of the dough in the extensograph showed a negative relationship with the amount of red ginseng marc powder added.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.6
• /
• pp.633-638
• /
• 2012

The maximum spreading is the maximum extent to which a drop can spread after impacting on a surface. It is one of the crucial factors determining the spraying performance in many applications. In this study, the existing maximum spreading models for a Newtonian liquid droplet impacting on a dry solid surface were reviewed and compared with the experimental results over the ranges of $4{\leq}Re{\leq}11700$, $23{\leq}We{\leq}786$, and $37.9^{\circ}{\leq}{\theta}_s{\leq}107.1^{\circ}$. The surface wettability was found to have only a minor influence on the maximum spreading, compared to the liquid viscosity and impact velocity. Among the models tested, the Roisman (2009) model showed the best agreement with the experimental results, matching 80% of the measured data within ${\pm}5%$.

• Korean Journal of Food Science and Technology
• /
• v.31 no.4
• /
• pp.994-998
• /
• 1999

To evaluate the effects of sucrose-fatty acid ester (SE) on bread-making characteristics, the dough mixing, gelatinization, baking properties with the addition of SE alone and together with other surfactants were investigated. SE increased the peak time and the peak height in mixogram, indicating that it contributed the elasticity of dough. In farinogram, SE increased the peak time and mechanical tolerance index, but reduced the dough stability. SE increased the peak viscosity and reduced the gelatinization temperature and maximum consistency temperature in amylogram. SE increased the specific volume of bread loaf and retarded the increase in hardness of bread during storage, showing its anti-staling effects. The maximum anti-staling effect of SE was observed at 0.5% level. The addition of SE (0.2%), SSL (0.15%) and ES-95 (0.15%) blend showed the maximum specific loaf volume, and that of SE (0.25%) and SSL (0.25%) did the maximum anti-staling effect.

• The Korean Journal of Rheology
• /
• v.10 no.4
• /
• pp.234-246
• /
• 1998

The objective of this study is to investigate the correlation between steady shear flow (nonlinear behavior) and dynamic viscoelastic (linear behavior) properties for concentrated polymer solutions. Using both an Advanced Rheometic Expansion System(ARES) and a Rheometics Fluids Spectrometer (RFS II), the steady shear flow viscosity and the dynamic viscoelastic properties of concentrated poly(ethylene oxide)(PEO), polyisobutylene(PIB), and polyacrylamide(PAAm) solutions have been measured over a wide range of shear rates and angular frequencies. The validity of some previously proposed relationships was compared with experimentally measured data. In addition, the effect of solution concentration on the applicability of the Cox-Merz rule was examined by comparing the steady flow viscosity and the magnitude of the complex viscosity Finally, the applicability of the Cox-Merz rule was theoretically discussed by introducing a nonlinear strain measure. Main results obtained from this study can be summarized as follows : (1) Among the previously proposed relationships dealt with in this study, the Cox-Merz rule implying the equivalence between the steady flow viscosity and the magnitude of the complex viscosity has the best validity. (2) For polymer solutions with relatively lower concentration, the steady flow viscosity is higher than the complex viscosity. However, such a relation between the two viscosities is reversed for highly concentrated polymer solutions. (3) A nonlinear strain measure is decreased with increasing stran magnitude, after reaching the maximum value in small strain range. This behavior is different from the theoretical prediction demonstrating the shape of a damped oscillatory function. (4) The applicability of the Cox-Merz rule is influenced by the $\beta$ value, which indicates the slope of a nonlinear stain measure (namely, the degree of nonlinearity) at large shear deformations. The Cox-Merz rule shows better applicability as the $\beta$ value becomes smaller.