• Proceedings of the KSME Conference
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• 2000.11b
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• pp.508-513
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• 2000

HANJUNG has developed demonstration plant treating combustion flue gas such as dioxide($SO_2$) and nitrogen oxides(NOx). Before operating this system, we tested the inner airflow characteristic of demonstration plant in the front of plasma reactor field 1 and field 2. The experimental results of $25,000Nm^3/hr$ airflow are compared with the computational results using FLUENT code. It is found that the velocity distribution trends are matched the experimental results with the calculation results. To improve the eccentric airflow in the inlet hood, it is necessary to install the vertical guide vane as well as the horizontal guide vane.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.5
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• pp.1280-1290
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• 1995

In order to investigate the compression wave propagating in a high-speed railway tunnel, a numerical calculation was applied to the wave phenomenon occurring in a model tunnel. Unsteady, one-dimensional inviscid or viscous flows were solved by an explicit TVD scheme, and the calculated flows were compared with the results of measurement in real tunnels. Tunnel noises caused by emission of the compression wave were characterized in terms of excess pressure of compression wave, pressure gradient in the wave front and width of the compression wave. Calculated attenuation, pressure gradient and width of compression wave with the propagating distance agreed with the results of measurement in the real tunnels. The results also show that tunnel noises are proportional to the train velocity entering the tunnel.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.692-697
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• 2000

Recently, Flat flame burners are hilighted in high-load burners. Our study contains flow field analysis of a flat flame burner. In this paper, We analyzed the direction and magnitude of the velocity in a round tile type burner with swirl angles, $10^{\circ},\;30^{\circ},\;50^{\circ}$. In the case of swirl angle $10^{\circ}$, because axial momentum is larger than radial momentum, Recirculation region was weakly developed. In the case of swirl angle $50^{\circ}$, Flow in front of the tile is distributed for radial direction. And Recirculation region is large. So, We expect that the radiation can be transmitted from tiles and the recirculation region may cause $NO_x$ reduction.

• 한국가시화정보학회:학술대회논문집
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• 2003.11a
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• pp.83-86
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• 2003

Synchrotron X-ray micro imaging technique was employed to non-invasively monitor the water flow inside xylem vessels in a bamboo leaf. The phase contrast X-ray images clearly visualized plant anatomy and the rise of a water front inside the vessels. Consecutive X-ray images taken for 60 seconds revealed water rise kinetics against gravity in the xylem of a cut dry leaf taken from a bamboo tree. For the first time, traces of water rise, variation of contact angle between water and xylem wall as well as the internal structure of xylem were obtained. In xylem vessels, a repeating flow pattern has a typical flow velocity of $30.7{\mu}m/s$ and faster flow is established intermittently. It is concluded that the transmission type of X-ray micro imaging can be used as a powerful tool to investigate the ascent of sap in the xylem vessels at a resolution higher than that of MRI.

• Journal of Mechanical Science and Technology
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• v.16 no.5
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• pp.720-731
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• 2002

Flow with moving free surfaces is analyzed with an the Eulerian coordinate system. This study proposes a semi-implicit filling algorithm using VOF in which the PLIC (Piecewise Linear Interface Calculation) -type interface reconstruction method and the donor-acceptor-type front advancing scheme are adopted. Also, a new scheme using extrapolation of the stream function is proposed to find the velocity of the node that newly enters the computational domain. The effect of wall boundary conditions on the flow field and temperature field is examined by numerically solving a two-dimensional casting process.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.85-89
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• 2001

The problem of the transient interaction of a plane acoustic shock wave which has an infinitely steep wave front with a cylindrical or spherical elastic shell has been studied analytically from early fifties based on the integral transform and series solution techniques. Huang adopted an inverse Laplace transform, and used a finite number of terms of the infinite series expansion of the equations for the shells. In the 1990s, the results have been used by many authors for validation of computer codes. The object of this paper is to discuss the interaction between a moving source and submerged spherical shells. Since the center of source is moving the first contact location between the waves and shell changes depending on the source velocity and distance. These are considered in the analysis. Furthermore, constant source strength and decreasing strength are considered in the analysis. Radial velocities at several locations on the structure are obtained and the results are discussed.

• Wind and Structures
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• v.19 no.1
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• pp.75-88
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• 2014

The computational fluid dynamic is used to explore new aspects of the hill flow. This analysis focuses on flow dependency and the comparison of results from measurements and simulations to show an optimization turbulent model and the possibility of replacing measurements with simulations. The first half of the paper investigates a suitable turbulence model for determining a suitable site for a wind turbine. Results of the standard k-${\varepsilon}$ model are compared precisely with the measurements taken in front of the hilltop, The Reynolds Stress Model showed exact results after 1.0 times of hill steepness but the standard k-${\varepsilon}$ model and standard k-${\omega}$ model showed greater underestimation. In addition, velocity flow over Pha Taem hill topography and the reference geometry shape were compared to find a suitable site for a turbine in case the actual hill structure was associated with the trapezoid geometric shape. Further study of geometry shaped hills and suitable sites for wind turbines will be reported elsewhere.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.586-591
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• 1996

Through the analysis of many experimental post-dryout data, it is shown that the most probable flow regime near dryout or quench front is not annular flow but churn-turbulent flow when the mass flux is low. A correlation describing the initial droplet size just after the CHF position at low mass flux is suggested through regression analysis. In the post-dryout region at low pressure and low flow, it is found that the suggested one-dimensional mechanistic model is not applicable when the vapor superficial velocity is very low, i.e., when the flow is bubbly or slug flow regime. This is explained by the change of main entrainment mechanism with the change of flow regime. Therefore, the suggested correlation is valid only in the churn-turbulent flow regime ( $j_{g}$ $^{*}$＝0.5~4.5).).

• Journal of the Korean Society for Precision Engineering
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• v.17 no.5
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• pp.195-201
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• 2000

The fundamental spot welded sections of automobiles (hat-shaped and double hat-shaped sections) absorb most of the energy in a front impact collision. The sections of various thickness, shape and weld width on the flange lave been tested on axial impact crush load (Mass 40kg, Velocity 7.19m/sec) using a vertical air pressure crash est device Characteristics of impact collapse have been reviewed and a structure of optimal energy absorbing capacity is suggested.

• Journal of computational fluids engineering
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• v.14 no.3
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• pp.63-68
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• 2009

The motion of a rising liquid droplet is different that of a bubble motion. Treatment of liquid drops is more complex because internal motion must be considered. A 3D unstructured CFD code has been developed to solve incompressible N-S equation for the droplet simulation. This front-tracking consideration which the interface is tracked explicitly is very available to apply for not only exact interface topology but also the high schmidt number issue, such as $CO_2$ dissolution. This paper is forced on the zig-zag motion of the liquid droplet. The simulation shows that if the rising droplet is located at the corner of the zig-zag path, the velocity is low and shape of the droplet is more spherical shape, results in the less drag coefficient. Twin horse shoe vortexes behind the rising droplet are presented and the topology of the droplet is compared with an experimental result during one period of the path.