• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.60-60
• /
• 2021

Investigating Backward-Facing Step(BFS) flow is important in that it is a representative case for separation flows in various engineering flow systems. There have been a wide range of experimental, theoretical, and numerical studies to investigate the flow characteristics over BFS, such as flow separation, reattachment length and recirculation zone. However, most of such previous studies were concentrated only on the perpendicular step angle. In this study, several numerical investigations on the flow pattern over BFS with various step angles (10° ~ 90°) and expansion ratios (1.48, 2 and 3.27) under different Reynolds numbers (5000 ~ 64000) were carried out, mainly focused on the reattachment length. The numerical simulations were performed using an open source 3D CFD software, OpenFOAM, in which the velocity profiles and turbulence intensities are calculated by RANS (Reynolds Averaged Navier-Stokes equation) and 3D LES (Large Eddy Simulation) turbulence models. Overall, it shows a good agreement between simulations and the experimental data by Ruck and Makiola (1993). In comparison with the results obtained from RANS and 3D LES, it was shown that 3D LES model can capture much better and more details on the velocity profiles, turbulence intensities, and reattachment length behind the step for relatively low Reynolds number(Re < 11000) cases. However, the simulation results by both of RANS and 3D LES showed very good agreement with the experimental data for the high Reynolds number cases(Re > 11000). For Re > 11000, the reattachment length is no longer dependent on the Reynolds number, and it tends to be nearly constant for the step angles larger than 30°.) Based on the calibrated and validated numerical simulations, several additional numerical simulations were also conducted with higher Reynolds number and another expansion ratio which were not considered in the experiments by Ruck and Makiola (1993).

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.28 no.3
• /
• pp.547-553
• /
• 1999

Effects of oligosaccharides substituted for sucrose on the sponge cake quality were investigated. Fructooligosaccharide and isomaltooligosaccharide were used as oligosaccharides. Oligosaccharides decreased batter specific gravity, and increased cake specific volume and expansion ratio, showing that oligosaccharides had higher foaming ability and foam stability than sucrose. Oligosaccharides darkened the crust and crumb color of cakes. Addition of oligosaccharides made cakes darker, softer, more moist and more acceptable as perceived by panels. The acceptability was significantly correlated with crust and crumb color, softness, moistness and flavor(p<0.01). The textural characteristics including hardness, chewiness and gumminess of cakes were decreased by replacing sucrose with oligosaccharides. The hardness, gumminess and chewiness among sensory characteristics were negatively correlated with acceptability(p<0.05). Therefore, oligosaccharides should be a good alternative for sucrose in cake making because the sponge cake quality was greatly improved by partial repacement of sucrose with oligosaccharides.

• Polymer(Korea)
• /
• v.29 no.6
• /
• pp.605-612
• /
• 2005

This study investigates the isothermal crystallization behaviors of polypropylene-polyethylene-(1-butene) terpolymer and the adiabatically expanded polyolefin structured foams. For this purpose, butane gas was used as a physical blowing agent. Avrami equation has been used to interpret theoretically the experimental results obtained by either DSC or polarized optical microscope. It is believed that elongation induced crystallization occurring during the adiabatic expansion process has resulted in an increase in crystallization rate, eventually leading to a faster growth rate of spherulites and an increase in the nucleation density. An analysis of the foam by SEM images showed that the structure of foam is uniform (below diameter 30 $\mu$m closed cell) In addition, the thermal conductivity and the compressive strength of the polyolefin structured foams was measured. The thermal conductivity of foamed resin with excellent insulation characteristics is reduced compared with unfoamed resin. The compressive strength is decreased with increase in the expansion ratio.

• Asia-Pacific Journal of Business
• /
• v.11 no.1
• /
• pp.145-165
• /
• 2020

Purpose - The purpose of this study is to suggest strategies and solutions for entering China in the tariff and non-tariff sectors of the cosmetic industry. Design/methodology/approach - This study analyzed the import tariff rate of cosmetics in China, and analyzed the export cost by actually interviewing the exporting companies to derive the economic effect of non-tariff measures. Findings - First, We proposed the use of the FTA business model (basic cosmetics), the use of Korea-China FTA tariffs (foam cleansing, toothpaste), and the use of APTA tariffs (perfume). Second, We proposed cooperation between the governments to facilitate customs clearance procedures and improvement of FTA awareness among corporate practitioners. Third, We proposed the expansion and support of the AEO MRA system and the expansion of Korea-China MOU conclusions regarding the certification system, and the international standardization of domestic licensing system and technical conditions. Fourth, We proposed the use of government-supported projects related to obtaining overseas certifications and overseas expansion through collaboration with the same industry. Research implications or Originality - HS3304 products excluded from the Korea-China FTA should take full advantage of the FTA business model. In addition, the non-tariff measure costs are fixed costs per year, so the ratio decreases as the number of exports and export volume increases.

• Korean Journal of Food Science and Technology
• /
• v.24 no.3
• /
• pp.294-299
• /
• 1992

This study was to examine the effect of functional properties of soy protein isolate(SPI) and qualities of soybean curd upon proteolytic hydrolysis. SPI was hydrolyzed using proteolytic enzyme, bromelain. The protein content of SPI by microkjeldahl method was 84% and the degree of hydrolysis in modified soy protein isolate(MSPI) was 2.7%. The solubility of MSPI was higher than that of control at various pH tested and proteolytic hydrolysis was increased emulsion formation and foam expansion while decreased emulsion stability, foam stability and calcium precipitation. Modified soybean curdI, standard soybean milk: Modified soybean milk=3:1, was soft and springy soybean curd when the texture properties of soybean curd were tested by texture profile analysis using Instron and sensory evaluation. The rheological model of soybean curds was investigated by stress relaxation test. The analysis of relaxation curve revealed that the rheological behavior of soybean curds could be expressed by 7-element generalized Maxwell model. The equilibrium modulus and modulus of elasticity decreased as the ratio of modified soybean milk was increased.

• Applied Biological Chemistry
• /
• v.39 no.4
• /
• pp.282-286
• /
• 1996

To effectively utilize fish skin gelatin as a material for quality improvement in surimi gel from fish with a red muscle, conger eel skin gelatin was modified with succinic anhydride, and funtional properties such as emulsifying activity and emulsifying stability were determined. The degree of chemical modification incresed up to 0.3 g of succinic anhydride/g of gelatin, above this adding ratio a nearly constant value was reached. The maximum amount of modification was about 90%. The emulsifying activity and emulsifying stability of gelatin gradually increased up to 89.8% of succinylation extent, little changed above of succinylation extent. The other functional properties as solubility, water holding capacity, foam expansion and foam stability were improved following succinylation with 0.3 g of succinic anhydride/g of gelatin. Amino acid composition of succinylated gelatin was similar to that of unmodified gelatin. Heavy metal contents such as cadmium, lead, copper and zinc of succinylated gelatin were lower than those of unmodified gelatin.