• Food Science and Biotechnology
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• 제18권4호
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• pp.1013-1018
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• 2009

Several rheological terms were introduced to estimate the properties of cooked noodles with different starch content using tensile tests. Ring-shaped specimens were prepared by connecting both ends of the noodle strip before cooking. Hencky strain and rate, as well as true stress were applied in constant deformation tests. The elastic region on the curves of strain vs. stress was not clearly identified. Strain hardening in the subsequent plastic region was more prominent in low-starch noodles. Elongational viscosities at lower strain rates were used to differentiate noodles with different starch content, representing the dominant effect of protein content in the range of lower strain rates. In stress relaxation tests, the reciprocal of Peleg's constant $K_1$ (initial decay rate) and $K_2$ (asymptotic level) increased and decreased respectively, with an increase in starch content. This indicated that addition of starch contributed to the noodles becoming viscous liquid rather than elastic solid.

• 한국분말재료학회지
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• 제15권4호
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• pp.297-301
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• 2008

The Ni-based bulk metallic glass matrix composites were fabricated by spark plasma sintering of mixture of gas-atomized metallic glass powders and ductile brass powders. The successful consolidation of metallic glass matrix composite was achieved by strong bonding between metallic glass powders due to viscous flow deformation and lower stress of ductile brass powders in the supercooled liquid state during spark plasma sintering. The composite shows some macroscopic plasticity after yielding, which was obtained by introducing a ductile second brass phase in the Ni-based metallic glass matrix.

• The Korean Journal of Ceramics
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• 제1권3호
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• pp.155-159
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• 1995

Borosilicate, $B_2O_3$ and BN derived from liquid precursors have been tested as shielding materials for the long period of oxidation resistance of C/BN composites at $650^{\circ}C$. Borosilicate coating displayed excellent oxidation resistance and low moisture absorbance, while $B_2O_3$ and BN were less effective in elevating the oxidation resistance. The enhancement of the oxidation resistance was explained as self-healing effect by viscous flow of the borosilicate glass over Tg, resulting in the reduction of the exposed carbon fibers in a BN matrix.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2001년도 유체기계 연구개발 발표회 논문집
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• pp.258-263
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• 2001

A fuel pump for a turbopump system has been designed under an international co-work program. The liquid methane fuel pump has an inducer, in front of centrifugal impeller blades, to improve cavitation performance. The three dimensional viscous flow in the fuel pump was investigated through numerical computation. An arrangement of the inducer and impeller has yielded a strong interaction between inducer and impeller blades. The performance of the pump was evaluated from the calculated results. A parametric study was performed for various design variables, and it could oner a database for design parameters to design a fuel pump. A modified design of a fuel pump was proposed by KIMM to improve pump performance.

• Korea-Australia Rheology Journal
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• 제16권4호
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• pp.219-226
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• 2004

In this study the deformation of liquid-air interface of Newtonian or Boger fluids filled between two par­allel-plates geometry was investigated when two surfaces were separated at a constant speed. The interface between the fluid and air showed either stable or unstable deformation depending on experimental con­ditions. Repeated experiments for a wide range of experimental conditions revealed that the deformation mode could be classified into three types: 'stable region', 'fingering' and 'cavitation'. The experimental condition for the mode of deformation was plotted in a capillary number vs. Deborah number phase plane. It has been found that the elasticity of Boger fluids destabilize the interface deformation. On the other hand, the elasticity suppresses the formation and growth of cavities.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.20-24
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• 2011

In this paper, numerical simulation of cavitation flow for modified NACA66 hydrofoil was made by using the multi-phase RANS equation based on pseudo-compressibility. The Homogeneous mixture model comprised of the mixture continuity, mixture momentum and liquid volume fraction equations was utilized. A vertex-centered finite-volume method was used in conjunction 2nd-order Roe's FDS to discretize the inviscid fluxes. The viscous fluxes were computed based on central differencing The Spalart-Allmaras one equation model was employed for the closure of turbulence. Reasonable agreements were obtained between the calculation results and the experiment for pressure coefficients on the hydrofoil surface.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1863-1868
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• 2008

In an electrospinning process, nanofibers are produced from a droplet of a viscoelastic polymer solution subjected to strong electric field. To date, intrinsic bending instability of the electrical jets has resulted in random piles of nanofibers on a grounded collector plate. Here we report a novel electrospinning process where a hollow micropillar is constructed by the coiling of nanofibers on a sharp grounded collector. We show that the hollow microstructure formation can be explained by the viscous fluid rope coiling theory. The current process can be employed for the fabrication of three-dimensional scaffolds for cell culturing and the three-dimensional nanoprinting.

• 한국미생물·생명공학회지
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• 제21권5호
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• pp.478-485
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• 1993

The strain which produced highly viscous exopolysaccharides (EPS) in liquid culture was selected from soil. The strain was supposed to Bacillus sp. from the results of mophological, biochemical and physiological tests. The medium composition for EPS production was trypton 0.75%, sucrose 4%, CaCO3 0.01%, Winogradsky's nitrogen free mineral medium 5ml/l and pH 7.0. In 2-l jar fernenter, the viscosity of culture broth after 120-hr cultivation time was very high (60, 000 cps) and the amount of EPS was 6.2g/l.

• 한국분말재료학회지
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• 제14권6호
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• pp.399-404
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• 2007

The Cu-based bulk metallic glass (BMG) composite was fabricated by spark plasma sintering (SPS) using of gas-atomized metallic glass powders and ductile brass powders. No defect such as pores and cavities was observed at the interface between the brass powder and the metallic glass matrix, suggesting that the SPS process caused a severe viscous flow of the metallic glass and brass phases in the supercooled liquid region, resulting in a full densification. The BMG composites shows some macroscopic plasticity after yielding, although the levels of strength decreased.

• Journal of Information Display
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• 제5권1호
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• pp.34-40
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• 2004

Time resolved infrared IR absorption spectroscopy is carried out to investigate the dynamics of electric field induced reorientation of the biphenyl molecular core and alkyl tail sub-fragments of the nematic liquid crystal 5CB (4-pentyl-4-cyano-biphenyl). The planar to homeotropic transition for high pre-tilt planar aligned cells, is studied for switching times ranging from 200 ${\mu}sec$ down to 80 ${\mu}sec$, the latter a factor of 1000 times faster than any previous nematic IR study. The reorientation rates of the core and tail are found to be the same to within experimental error and scale inversely with applied field squared, as expected for the balance of field and viscous torques. Thus any molecular conformation change during switching must relax on a shorter time scale. A simple model shows that no substantial differences exist between the reorientational dynamics of the tails and cores on the time scales longer than on the order of 10 ${\mu}s$.