• Journal of computational fluids engineering
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• v.20 no.3
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• pp.62-69
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• 2015

Pressure change inside cabin as well as in tunnel has been calculated to assess the passenger pressure comfort of high-speed train. $C-STA^{TM}$, a CFD program based on axi-symmetric Navier-Stokes equation and Roe's FDS has been used to simulate the pressure change in tunnel during a high-speed train passing through it. To present the relative motion between the train and the tunnel, a modified patched grid scheme based on the structured grid system has been employed. The simulation program has been validated by comparing the simulation results with field measurements. Extensive parametric study has been conducted for various train speed, tunnel cross-sectional area and tunnel length to the pressure change in cabin. KTX-Sancheon(KTX2) high-speed train has been chosen for simulation and the train speed have been varied from 200 km/h to 375 km/h. The tunnel length has been varied from 300 m to 7.5 km and tunnel area from $50m^2$ to $120m^2$. Total 504 simulations have been conducted varying the parameters. Based on the database produced from the parametric simulations, minimum tunnel cross-sectional area has been surveyed for various train speeds based on Korean regulation on pressure change in cabin.

• Journal of Magnetics
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• v.6 no.1
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• pp.23-26
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• 2001

Nano-crystalline hexaferrite $BaFe_{12}O_{19}$(BaM) thin films have been prepared by the sol-gel method. A solution of Ba-nitrate and Fe-nitrates was dissolved in solvent with the stoichiometric ratio Ba/Fe=1/10. Films were spin-coated onto $SiO_2$Si substrates, dried and then heated in air at various temperatures. In films prepared at a drying temperature $T_d=250^{\circ}C$ and a crystallizing temperature 650${\circ}C$, single-phase BaM was obtained. High coercivities were obtained in these nano-crystalline thin films, 4~5.5 kOe for hexaferrite. Polycrystalline BaM/$SiO_2$/Si(100) thin films were characterized by Rutherford backscattering (RBS), thermogravimetry (TGA), differential thermal analysis (DTA), x-ray diffraction (XRD), and vibrating sample magnetometry (VSM), as well as Fourier transform infrared spectroscopy (FTIR). The perpendicular coercivity $H_{C\bot}$ and in-plane coercivity $H_{CII}$ after annealing at 650${\circ}C$ for 2 hours were 4766 Oe and 4480 Oe, respectively, at room temperature, under a maximum applied field of 10 kOe.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1595-1600
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• 2004

When a shock wave arrives at a duct, an impulsive wave is discharged from the duct exit and causes serious noise and vibration problems. In the current study, the characteristics of the impulsive wave discharged from a partial closed duct exit is numerically investigated using a CFD method. The Yee-Roe- Davis's total variation diminishing(TVD) scheme is used to solve the axisymmetric, unsteady, compressible Euler equations. With several partial closed duct exits, the Mach number of the incident shock wave $M_s$ and the distance L/D between the duct exit and a flat plate are varied in the range of $M_s$ = 1.01 ${\sim}$ 1.50 and L/D = 1.0 ${\sim}$ 4.0, respectively. The results obtained show that the magnitude of the impulsive wave impinging upon the flat plate strongly depends upon $M_s$, L/D and the partial closure of duct exit. The impulsive wave on the flat plate can be considerably alleviated by the partial closure of duct exit and, thus, the present method can be a passive control for the impulsive wave.

• Journal of Nutrition and Health
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• v.45 no.1
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• pp.94-102
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• 2012

There is a limitation to estimate vitamin $B_{12}$ intake due to a lack of data on vitamin $B_{12}$ content in many Korean foods. In this study, vitamin $B_{12}$ content was determined in some seaweeds, fish, and shellfish and their product that are consumed in Korea using a modified microbioassay with Lactobacillus delbruecki ATCC 7830. Dried laver and dried seasoned and toasted laver contained very high levels of vitamin $B_{12}$ (66.8 and $55.2-71.3\;{\mu}g$/100 g, respectively. Sea lettuce and seaweed fulvescene also contained high vitamin $B_{12}$ content of 5.47-9.41 and $6.46-7.20\;{\mu}g$/100 g, respectively, whereas sea mustard and sea tangle contained low levels of vitamin $B_{12}$; vitamin $B_{12}$ was not detected in seaweed fusifome. Pacific saury, trout, sea-bass, or squid contained 12.01, 2.00, 0.49 and $2.33\;{\mu}g$ vitamin $B_{12}$/100 g, respectively. Ochellatus octopus, and naked sand lance contained 0.72-1.43 and $3.68\;{\mu}g$ vitamin $B_{12}$/100 g, respectively. Dried Alaska pollack con-tained $0.19-2.64\;{\mu}g$ vitamin $B_{12}$/100 g. Shellfish such as little neck clam and small ark shellfish contained high levels of vitamin $B_{12}$ of $30.5-40.5\;{\mu}g$/100 g, and mussel and abalone contained 17.71 and $7.82\;{\mu}g$/100 g, respectively. Of unique Korean traditional fermented seafood products, salt-fermented products of squid ($2.91\;{\mu}g$/100 g), clams ($34.31\;{\mu}g$/100 g), Ala-ska pollack roe ($9.98-12.02\;{\mu}g$/100 g), hairtail guts ($4.58\;{\mu}g$/100 g) or small shrimp ($0.58-1.55\;{\mu}g$/100 g), and fish sauce from anchovies ($1.52-1.78\;{\mu}g$/100 mL), sand eel ($0.22-0.24\;{\mu}g$/100 mL) or small shrimp ($0.19-0.78\;{\mu}g$/100 mL) were analyzed. A few commercial brands of flying fish roe ($0.73-1.73\;{\mu}g$/100 g), canned tuna ($0.40\;{\mu}g$/100 g), and fried fish paste ($0.25-0.69\;{\mu}g$/100 g) were also analyzed. In conclusion, vitamin $B_{12}$ content in these foods, chosen considering the Korean food culture, should contribute to improve the present vitamin $B_{12}$ food database. It may be helpful to estimate vitamin $B_{12}$ intake more correctly than before, and provide additional information for dietary education related to vitamin $B_{12}$ and meal management.

• Journal of computational fluids engineering
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• v.12 no.1
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• pp.43-52
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• 2007

A comparative study on flux functions for the 2-dimensional Euler equations has been conducted. Explicit 4-stage Runge-Kutta method is used to integrate the equations. Flux functions used in the study are Steger-Warming's, van Leer's, Godunov's, Osher's(physical order and natural order), Roe's, HLLE, AUSM, AUSM+, AUSMPW+ and M-AUSMPW+. The performance of MUSCL limiters and MLP limiters in conjunction with flux functions are compared extensively for steady and unsteady problems.

• 대한핵의학회:학술대회논문집
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• 1969.12a
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• pp.1.4-2
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• 1969

• 한국전산유체공학회:학술대회논문집
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• 1998.11a
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• pp.48-54
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• 1998

Three-dimensional incompressible Navier-Stokes equations have been solved by the node-centered finite volume method with unstructured hybrid grids. The pressure-velocity coupling is handled by the artificial compressibility algorithm and convective fluxes are obtained by Roe's flux difference splitting scheme with linear reconstruction of the solutions. Euler implicit method is used for time-integration. The viscous terms are discretised in a manner to handle any kind of grids such as tetrahedra, prisms, pyramids, hexahedra, or mixed-element grid. The numerical efficiency and accuracy of the present method is critically evaluated for several example problems.

• Journal of Microbiology
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• v.35 no.4
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• pp.264-270
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• 1997

The structure of plasmid mlp1, a linear 10.2kb mitochondrial plasmid of Pleurotus ostreatus NFF A2 was determined by restriction enzyme mapping and partial sequencing. The plasmid encodes at least two proteins; a putative RNA polymerase showing homology to yeast mitochondrial RNA polymerase and to viral-encoded RNA polymerases, and a putative DNA polymerase showing significant homology to the family B thpe DNA polymerases. It also contains terminal inverted repeat sequences at both ends which are longer than 274 bp. A 1.6 kb EcoRI restriction fragment of m1p1 containing the putative RNA polymerase gene did not hybridize to the nuclear or motochondrial genomes from P. ostreatus, suggesting that it may encode plasmidspecific RNA polymerase. The gene fragment also did not hybridize with the RNA polymerase gene (RPO41) from Saccaromyces cerevisiae. The relationship between genes in m1p1 and those in another linear plasmid pC1K1 of Claviceps purpurea was examined by DNA hybridization. The result indicates that the genes for DNA and RNA polymerases are not closely related with those in C. purpurea.

• Journal of Microbiology
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• v.33 no.3
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• pp.215-221
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• 1995

S. coelicolor A3(2) cells were treated with various redox-cycling agents on nutrient agar plates and examined for their effect on the growth and differentiation. When treated with plumbagin, severe effect on cell viability was observed at concentrations above 250 $\mu$M. However, the surviving colonies differentiated normally. When treated with 100 $\mu$M paraquat, growth rate was decreased and morphological differentiation was inhibited, while the survival rate was maintained at about 100% even at 5 mM paraquat. Menadione or lawsone did not cause any visible changes at concentrations up to 1 mM. The effect of paraquat was also observed when it was added to nutrient agar plate before spore inoculation. Paraquat had also observed when it was added to nutrient agar plate before spore inoculation. Paraquat had no effect on colonies growing on R2YE agar plates. Among the components of R2YE medium selectively added to nutrient agar medium, CaCl$_2$ was found to have some protective function from the inhibitory effect of paraquat. As a first step to study the mechanism of the inhibitory effect of paraquat on differentiation, resistant mutants which sporulate well in the presence of paraquat were screened following UV mutagenesis. Three paraquat-resistant mutants were isolated with a frequency of 3 $\times$10${-5}$. Their mutation sites were determined by genetic crossings. All three mutations were mapped to a single locus near arg4 at about 1 o'clock on the genetic map of S. coelicolor A3(2).

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.33-36
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• 2006

As the computing environment is rapidly improved, the interests of CFD are gradually focused on large-scale computation over complex geometry. Keeping pace with the trend, essential computational tools to obtain solutions of complex aerospace flow analysis and design problems are examined. An accurate and efficient flow analysis and design codes for large-scale aerospace problem are presented in this work. With regard to original numerical schemes for flow analysis, high-fidelity flux schemes such as RoeM, AUSMPW+ and higher order interpolation schemes such as MLP (Multi-dimensional Limiting Process) are presented. Concerning the grid representation method, a general-purpose basis code which can handle multi-block system and overset grid system simultaneously is constructed. In respect to design optimization, the importance of turbulent sensitivity is investigated. And design tools to predict highly turbulent flows and its sensitivity accurately by fully differentiating turbulent transport equations are presented. Especially, a new sensitivity analysis treatment and geometric representation method to resolve the basic flow characteristics are presented. Exploiting these tools, the capability of the proposed approach to handle complex aerospace simulation and design problems is tested by computing several flow analysis and design problems.