• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.392-397
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• 2001

A numerical study is performed to investigate the interaction between subsonic axial turbine blade boundary layer and periodically oncoming rotor induced wakes. An implicit scheme for solving the compressible Navier-Stokes equation is developed, which adopts a 4th-order compact difference for spatial discretiztion, a 2nd order Crank-Nicolson scheme for temporal discretization and the dynamic eddy viscosity model as the subgrid scale model. The efficiency and the accuracy of the proposed method are verified by applying to some benchmark problems such as laminar cylinder flow, laminar airfoil cascade flow and a transitional flat plate boundary layer flow. Computational results show good agreements with previous experimental and numerical results. Finally, flow through a stator cascade is simulated at $Re = 7.5{\times}10^5$ without free-stream turbulence intensity. The velocity fields and skin friction coefficients in the transitional region show similar trends with previous boundary layer natural transition.

• 대한치과교정학회지
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• 제6권1호
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• pp.47-54
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• 1976

This study was conducted to investigate the effects of multibanded orthodontic appliances on dental caries activity. The subjects consisted of 50 males and females with multibanded orthodontic appliance and the same number of caries free group. The following conclusions were obtained, 1. There was significant difference between the experimental group and control group in the tests of Snyder colorimetric test, acid :buffering capacity and oral glucose clearance test (at $5\%$ level of significance). 2. There was no significant difference between the experimental group and control group in the tests of unstimulated salivary flow fate, stimulated salivary flow rate and salivary viscosity test (at $5\%$ level of significance). 3. Dental caries activity was higher in experimental group than in control group.

• 한국해양공학회지
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• 제4권1호
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• pp.49-54
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• 1990

This study describes the application of a two dimensional depth integrated numerical model. The explict scheme of finite difference method had been applied to the model of circulation. The nonlinear terms showed a slight difference for the variations of water elevation when calculated grid was small. They were also found to be minor when calculated grid size was increased. For verification of the numerical model, numerical results were compared with predicted values and field data. In the model, the effect of nonlinear advective terms proved not to be significant.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.179-182
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• 2005

We have developed a numerical scheme to reproduce the unsteady flows with cavitation by the finite-difference method. The evolution of cavitation is represented by the source/sink of vapor phase in the incompressible liquid flow. The pressure-velocity coupling is based on the fractional-step method for incompressible fluid flows, in which the compressibility is taken into account through the low Mach number assumption. We applied our method for the cavitating flows in a two-dimensional cascade, which approximates the portion near the tip of inducer in liquid-fuel engine. Particular attention was focused on the influence of turbulence model in this report. Using an eddy viscosity model, although it was not an optimized one for our purpose, the agreement with the experimental observation was improved.

• 한국식품조리과학회지
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• 제6권2호
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• pp.59-66
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• 1990

The characteristics of sponge cakes containing sucrose or other sweeteners for diabetes mellitus patients were investigated through physical measurement and sensory evaluation. The results are as follows: The physical properties of cake batters and cakes with sweeteners were different from each other in viscosity, specific gravity, standing height, firmness, and springiness. from the result of sensory evaluation, it was shown that cakes containing sorbitol and fructose had high quality even though they were not as good as cake with sucrose. However, cakes with saccarine and stevioside showed much difference compared with cake with sucrose. The characteristics of sponge cake with combined sweeteners (sorbitol plus stevioside) were compairable to those of sucrose cake. There was little difference in specific gravity. The result of sensory evaluation indicated the combined use of both sweetenes could produce bette cakes than either stevioside or sorbitol. Practical utilization of this cake would be provided under the sensory evaluation on these cakes by diabetes mellitus patients.

• 한국정밀공학회지
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• 제16권4호통권97호
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• pp.46-56
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• 1999

A semi-actively controlled impact system which adjusts an impulse exerted by the external impact is studies. The main control variables are internal pressure difference inside the cylinder and the shock absorber displacement while it travels. Compared to a conventional one so called a passive system with a variable orifice inside the cylinder, a semi-actively controlled system utilizes an external orifice controlled by a highly fast responding electrical proportional valve. This device overcomes the temperature and viscosity change due to continuous operating and keeps the desired pressure difference and displacement in every operation. In this article a new prototype impact system is designed and manufactured based on a semi-actively control system. Through computer simulations and experiments, we verify the possibility of controlling the shock absorber pressure and displacement. After investigating the control performance a modified semi-actively controlled system with better control performance is also proposed.

• Food Science and Biotechnology
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• 제14권3호
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• pp.328-333
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• 2005

Finite difference model and dynamic thermal property evaluation system were developed to estimate convection heat transfer coefficient by modeling temperature-time profile of beef cube in continuous flow sterilizing system. As input parameters of the model, specific heat and thermal conductivity values of beef frankfurter meat were independently measured from 20 to $80^{\circ}C$. Convection heat transfer coefficient was estimated by comparing simulated and measured temperature-time profiles. Actual temperature-time profiles of meat cube were measured at flow rates of 15, 30, and 45 L/min and viscosities from 0 to 15 cp, and mean values of convection heat transfer coefficients ranged from 792 to $2107\;W/m^2{\cdot}K$. Convection heat transfer coefficient increased with increase in flow rate and decreased as viscosity increased.

• Food Science and Biotechnology
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• 제15권5호
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• pp.721-727
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• 2006

This study was carried out to investigate the effect of hydrocolloids on the changes in physical properties of a model ice cream. The model ice cream contained water, sugar, skin milk powder, com oil, and 4 different hydrocolloid stabilizers (gelatin, pectin, hydroxyethylstarch, locust bean gum), was manufactured in a batch type freezer. The following physical characteristics of ice cream were examined: flow behavior, overrun, air cell size, ice crystal size, and melt resistance. With regard to flow behavior, all of aged mixes had a lower apparent viscosity relative to the mix before aging, and ice cream mix containing locust bean gum had the highest viscosity. Air cell size was observed to range from 20 to $38\;{\mu}m$, and ice cream with locust bean gum showed the largest size. There was an inverse correlation between overrun and air cell size. The ice crystal sizes of all samples ranged from 25 to $35\;{\mu}m$. Ice cream with added pectin contained the smallest ice crystal size, which was significantly difference from other stabilizers (p<0.05), and resulted in superior melt resistance with increased melting time compared to other samples.

• Transactions on Electrical and Electronic Materials
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• 제7권1호
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• pp.30-35
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• 2006

We have studied the motion of charged micro-particles that are immersed in a nematic liquid crystal (LC) and controlled by in-plane field. The LC is an anisotropic liquid such that the viscosity of the LC depends on flow direction, phase of the LC, and temperature, which affects the motion of the charged particles under the influence of electric field. This study shows that the motion of charged particles mainly depends on the applied voltage and the LC phase, but does not show any significant influence from the initial alignment of LC, although one may expect directional difference in drag force due to interaction between LC and particle. The viscosity changes due to temperature variations in nematic phase also show no signification influence on particle velocity when compared to the effect from varying in-plane field strength.

• 한국식품저장유통학회지
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• 제6권1호
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• pp.76-80
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• 1999

Power consumption, mesh size, moisture content, color difference, amylogram of rice flour milled with the water soaked rice were compared with that of rice using dry pin mill process. The rice was soaked in 23, 24, 25, 26% of water for 10hr, independently. The more rice had moisture content, the less power consumption was needed. Power consumption to mill the rice soaked in 25% of water was less than that of dry rice by 6.8kW/100Kg. Moisture content of rice flour from the rice soaked with 25% of water was 2% higher than that of rice flour from the rice soaked with 23% of, water. Population of flour particle from the rice soaked with 24-25% of water was 45.7∼46.25 of 60 mesh, 9.7∼10.4% of 80∼100 mesh and 7.7∼8.1% of 100 mesh. Gelatinization temperature of rice flour from the rice soaked with 23% and 24∼25% of water was 65.70C and 64.50C, independently. Temperature of rice flour from the rice soaked with 23% 24∼25% of water sith minimum viscosity was 85.50C and 88.4∼88.70C, independently. Brightness and whiteness of the rice flour from the rice soaked with 24∼25% of water were 95.90∼95.95 and 905.82∼95.94, independently. Brightness and whiteness of the rice flour from the soaked rice were 1.2 and 1.7 higher than that of rice flour from the dry rice, independently.