• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.7
• /
• pp.675-682
• /
• 2013

To verify the effect of inner- and outer-stage gas jets, a shear coaxial injector was designed to analyze the axial velocity profile and breakup phenomenon with an increase in the measurement distance. When the measurement position was increased to Z/d=100, the axial flow showed a fully developed shape due to the momentum transfer, aerodynamic drag effect, and viscous mixing. An inner gas injection, which induces a higher momentum flux ratio near the nozzle, produces the greater shear force on atomization than an outer gas injection. Inner- and Outer-stage gas injection do not affect the mixing between the inner and outer gas flow below Z/d=5. The experiment results showed that the main effect of liquid jet breakup was governed by the gas jet of an inner stage. As the nozzle exit of the outer-stage was located far from the liquid column, shear force and turbulence breaking up of the liquid jets do not fully affect the liquid column. In the case of an inner-stage gas injection momentum flux ratio within 0.84, with the increase in the outer gas momentum flux ratio, the SMD decreases. However, at an inner-stage gas jet momentum flux ratio over 1.38, the SMD shows the similar distribution.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.37 no.11
• /
• pp.1479-1484
• /
• 2008

This study was conducted to investigate the quality characteristics of fermented-defatted soybean grits (DSG). Fermented-DSG was prepared by inoculating Bacillus subtilis NUCI into steamed DSG at 2% (v/w) concentration and fermenting at $40^{\circ}C$ for 24 hr. The protein contents of DSG and fermented-DSG were higher by $57.2{\sim}61.0%$ than those of Chungkukjang, but lipid contents of these samples were not detected. The protease and $\alpha$-amylase activities, and solid contents in DSG were not shown. However, the activities of protease and $\alpha$-amylase, tyrosine contents, fluid consistency, and viscous substance contents of fermented-DSG were higher than those of Chungkukjang. The levels of free amino acids and isoflavone of fermented-DSG tended to increase more than those of DSG. The sensory score of fermented-DSG were higher in odor and taste than those of Chungkukjang groups, while lower in color and overall acceptability.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.150.1-150.1
• /
• 2014

Showerhead is used as a main part in the semiconductor equipment. The face plate flatness should remain constant and the cleaning performance must be gained to keep the uniformity level of etching or deposition in chemical vapor deposition process. High operating temperature or long period of thermal loading could lead the showerhead to be deformed thermally. In some case, the thermal deformation appears very sensitive to showerhead performance. This paper describes the methods for robust design using computational fluid dynamics. To reveal the influence of the post distribution on flow pattern in the showerhead cavity, numerical simulation was performed for several post distributions. The flow structure appears similar to an impinging flow near a centered baffle in showerhead cavity. We took the structure as an index to estimate diffusion path. A robust design to reduce the thermal deformation of showerhead can be achieved using post number increase without ill effect on flow. To prevent the showerhead deformation by heat loading, its face plate thickness was determined additionally using numerical simulation. The face plate has thousands of impinging holes. The design key is to keep pressure drop distribution on the showerhead face plate with the holes. This study reads the methodology to apply to a showerhead hole design. A Hagen-Poiseuille equation gives the pressure drop in a fluid flowing through such hole. The assumptions of the equation are the fluid is viscous-incompressible and the flow is laminar fully developed in a through hole. An equation can be expressed with radius R and length L related to the volume flow rate Q from the Hagen-Poiseuille equation, $Q={\pi}R4{\Delta}p/8{\mu}L$, where ${\mu}$ is the viscosity and ${\Delta}p$ is the pressure drop. In present case, each hole has steps at both the inlet and the outlet, and the fluid appears compressible. So we simplify the equation as $Q=C(R,L){\Delta}p$. A series of performance curves for a through hole with geometric parameters were obtained using two-dimensional numerical simulation. We obtained a relation between the hole diameter and hole length from the test cases to determine hole diameter at fixed hole length. A numerical simulation has been performed as a tool for enhancing showerhead robust design from flow structure. Geometric parameters for the design were post distribution and face plate thickness. The reinforced showerhead has been installed and its effective deposition profile is being shown in factory.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.2
• /
• pp.528-535
• /
• 2016

Two types of oleophilic acrylic prepolymers were prepared by the solution copolymerization of either ethyl acrylate (EA) or lauryl acrylate (LA) with hydroxy ethyl acrylate (HEA). For the formation of oil-absorbent materials, a mixed solution of the prepolymer and hexamethylene diisocyanate (HDI) as a cross-linker in toluene was applied to polypropylene knit velvet fabric through the conventional pad-dry-cure procedure. The gel fraction of the crosslinked resin, EA-HEA-HDI, increased with increasing feed ratio of HEA to total acrylate or HDI concentration. The oil absorbancy and retention ratio of the prepared materials were compared according to the add-on ratio of resin to fabric, and were assessed with n-decane, toluene, soybean oil, lubricant and bunker C oil as test oils. The optimal oil absorbancy of the materials were observed at around 6% of the add-on ratio for all these oils except for soybean oil. On the other hand, the oil retention ratio increased as the add-on ratio increased. Futhermore, heavier and more viscous oil generally showed higher oil retention ratios. In addition, the oil absorbancy of the materials treated with LA-HEA-HDI resin was higher than that treated with EA-HEA-HDI resin, which showed that the acrylic resins are more absorptive with increasing length of their side alkyl chain.

• Microbiology and Biotechnology Letters
• /
• v.34 no.3
• /
• pp.196-203
• /
• 2006

Three slime-forming lactic acid bacteria were isolated from Kimchi and shown to produce viscous exopolysaccharides (EPS) in sucrose media. The isolated strains, GJ2, C3 and C11, were identified as Leuconostoc kimchii, Leuconostoc citreum and Leuconostoc mesenteroides, respectively, by examining their metabolic characteristics and determining their 16S rDNA sequences. Leu. kimchii GJ2, Leu. citreum C3 and Leu. mesenteroides C11 exhibited high viability (maintained initial viable cell count of $10^8$ CFU/ml) in 0.05 M sodium phosphate buffer (pH 3.0) for 2 h, in artificial gastric juice for 2 h and in 0.3% oxgall for 24 h. When tested, Leu. kimchii GJ2, in particular, displayed antimicrobial activity against pathogenic microorganisms. Leu. kimchii GJ2, Leu. citreum C3 and Leu. mesenteroides C11 produced 21.49 g/l, 16.46 g/l and 22.98 g/l EPS, respectively, in sucrose (5%) medium. The amount of purified EPS extracted from Leu. kimchii GJ2, Leu. citreum C3 and Leu. mesenteroides C11 was 14.61 g/l, 7.73 g/l and 4.77 g/l, respectively. Although the EPS produced by Leu. kimchii GJ2, Leu. citreum C3 and Leu. mesenteroides C11 differed in viscosity, TLC and HPLC analysis revealed that each contained only one type of monosaccharide, glucose. The average molecular mass of EPS produced by Leu. kimchii GJ2 was 306,606 Da.

• Journal of Life Science
• /
• v.19 no.6
• /
• pp.744-750
• /
• 2009

A bacterial strain producing highly viscous extracellular polysaccharide was isolated from soil. Through morphological, physiological and chemotaxonomical studies, it was identified as a Bacillus sp. and named Bacillus sp. PS-12. The extracellular polysaccharide, named PS-12 was purified by ethanol precipitation, cetylpyridinium chloride (CPC) precipitation and gel permeation chromatography. The purified polysaccharide was found to consist of glucose, mannose, galactose, and fucose, with a molar ratio of approximately 7:3.2:2:1, respectively. PS-12 was investigated for its immunostimulating activity on murine macrophage RAW264.7 cells using an ELISA assay. PS-12 stimulated the production of TNF-${\alpha}$ to a level 50 times greater than the control and also induced 1L-6 secretion in a dose-dependent manner. The cytotoxicity on RAW264.7 cells by PS-12 was relatively low with 10% cytotoxicity at 2 ${\mu}g$/ml. These results indicate that PS-12 is less cytotoxic to immune cells and possess immunomodulating activity in which it can produce cytokines including TNF-${\alpha}$ and 1L-6 from macrophages.

• Applied Biological Chemistry
• /
• v.40 no.6
• /
• pp.525-530
• /
• 1997

The changes in rheological properties of egg white stored in biodegradable package were investigated by pH change, failure stress and stress relaxation curve, and compared with control without package and complex PE. Initial pH of egg white stored in biodegradable package changed from 8.39 to 9.3 after 8 day storage, showing similar trend in pH change as that of control without package. Initial 14.25 N failure stress was changed into 6.76 N in biodegradable package and 9.31 N in control. Complex PE, having a relatively low gas permeability compared to biodegradable package, showed less pH changes from 8.30 to 8.81, but a greater decrease in failure stress into 5.29 N, indicating more deteriorating effect in complex PE package. Viscoelastic constants, such as elastic constant and viscous constant, obtained from stress-relaxation curve by three element Maxwell model were not significantly different between control and biodegradable package, but eggs stored in complex PE showed greater changes during storage. Therefore, the permeability seems to be the major factors to influence the rheological properties of egg and biodegradable packaging materials showed a potential substitute package for eggs.

• Applied Biological Chemistry
• /
• v.38 no.2
• /
• pp.135-140
• /
• 1995

Changes in pH of the soaking solution and physical properties of the soybean curd during immersing in solution of different concentrations at different temperatures were determined. Compared with $0{\sim}3%$ NaCl soaking solution, 5% NaCl soaking solution distinctively reduced the pH drop, increasing rate of turbidity and microorganism growth during storage. This indicated the concentration of soaking solution influences the shelf life of curd. As the storage temperature was lowered to $5^{\circ}C$, their changing rates were also reduced. Physical properties such as initial stress $({\sigma}_0)$, elastic constant (E), viscous constant $({\eta})$ and failure test were influenced by storage temperature, but not a function of concentration of salt solution. The result of the sensory test indicated the hardness and salty taste of curd were statistically significant among samples and $1{\sim}5%$ NaCl solutions did not show any significant difference in the salty taste.

• Applied Biological Chemistry
• /
• v.44 no.1
• /
• pp.24-29
• /
• 2001

Extracts of Acanthopanax koreanum Nakai were decreased as the ethanol concentration was increased, but eleutherosides were increased. Extracts were increased as the extraction time was prolonged. Compared to 15 hrs extraction, extract yield and eleutherosides for 5 hrs extraction were 90.6% and 96%, respectively. Yields of extract and eleutherosides were 6.5% and 75% at $100^{\circ}C$. The optimum extraction conditions were obtained from the samples of 4 years' tree harvested at September, which were water and 50% ethanol as solvents, and $90^{\circ}C$ for 5 hrs extraction. Soluble solids, minerals, free sugars, free acids, free amino acids and total eleutherosides in the extract of Acanthopanax koreanum were $48.2{\sim}47.4%$, $4.5{\sim}5.3%$, 11.2711.80%, $3.02{\sim}3.18%$, 185.33 mg/100 $g{\sim}$ 348.14 mg/100 g and 990.84 mg/100 $g{\sim}$l,416.10 mg/100 g, respectively. The extract was viscous and yellowish brown liquid.

• Journal of the Korean Society of Food Culture
• /
• v.16 no.4
• /
• pp.310-315
• /
• 2001

Flavor modifing effects of ${\beta}-cyclodextrin$ on the flavor of Chungkookjang(Korean traditional fermented bean paste) were investigated with varied substitution levels of 10, 20, and 30%. The 20% substituted sample groups showed significantly lower amount of protein and ash contents compared to those of control. The L value of brightness had significantly the largest value of 53.99 with 30% substituted sample group, and lower a and b values. Internal structures of control group observed using the scanning electronic microscope, had irregular round type shape with viscous materials, and they had tendencies to be less rough and organized making even and ordered internal cell structures as the substituted levels were increased. Results of sensory characteristics showed significantly lower off-odor and salty flavor with the 20% substituted sample groups compared to those of control. Results of this study showed the possibilities of flavor moderating effects of ${\beta}-cyclodextrin$ when it was used as one of the flavor modifier of the Chungkookjang. Future studies of finding the optimum level of substitution is further required.