• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.199-206
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• 2004

In the multi-burner power plant, uneven supplies of combustion air to multi-burner are induced by unbalanced flow distribution in the windbox. These flow patterns tend to make flame unstable, increase the formation of pollutants and lower the overall combustion efficiency. To prevent these disadvantages, flow patterns in the windbox should be investigated and made to be distributed uniformly, In this study, scaled windbox model was used for tests and measured the velocities at the exit of the each burner and compared those with the CFD results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.152-155
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• 2004

In the semi-solid die casting process, the important thing is the flow behaviors of semi-solid material. The flow patterns of semi-solid material can make the defects during die filling. To control of the flow patterns, is very important and difficult. In this paper, the flow behaviors of the semi-solid A356 alloy material during die filling at various die gate shapes has been observed with the grain size controlled material. The effects of the gate shape on the die filling characteristics were investigated. The filling tests in each plunger strokes were experimented, also simulated on the semi-solid material die casting process by MAGMAsofi. According to the filling tests and computer simulation, the effect of the gate shape on liquid segregation had been investigated.

• Journal of Ocean Engineering and Technology
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• v.7 no.1
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• pp.81-91
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• 1993

Studies on the flow pattern due to reclamation in the Myunggi-Nocksan region are carried out based on field observations and numerical experiments. Serial time series measurement of current, temperature and salinity were conducted for 1 tidal period at intervals of 1 hour from surface to bottom on station located at 128.deg. 54' 44" E, 35.deg. 01' 04" N in April and June 1992. Surface current opposite to the subsurface current causes turbulent mixing to make homogeneous salinity pattern in vertical section. Reclamation has little effect on the wave pattern and flow patterns are also nearly similar except on the nearby region of reclamation where flow speed somewhat weakened.

• Journal of Surface Science and Engineering
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• v.23 no.3
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• pp.160-166
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• 1990

The effects of the variation of proedd varibles on the flow patterns and effects of the flow patterns on the deposition rate and uniformity in the Si-epitaxy CVD with SiH4 as the source of Si were studied through the calculation by use of control volume method. The reslts showed that the natural convection was undesirable to the uniformity of deposition rate, whose effects were decreased with the dercrese with the decrese of the pressure in the reactoor and with the increase of the flow rate. However. the excessive increase of flow rate caused the movement of the unreacted gas to the substrate. Therefore it resulted in the non-uniform depositions. The rotation of substrate was apperared to improve the uniformity. The resulte of this study could used in CVD process to design the reator and to find the optimum conditions of the process variables.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1997.11a
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• pp.169-177
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• 1997

An experimental study has been conducted at an intermediate scale to study the effect of a cross flow on a purely buoyant fire. Video taping of the flame and post processing of the images by means of a novel technique provide a contour of a mean flame for all cases studied. This flame contour allows the determination of a mean flame length and a mean flame height. The mean flame length and height are recorded as functions of the forced flow velocity. Three dimensional flow patterns are formed in the flame trailing edge affecting both the mean flame length and height. The three dimensional patterns are studied systematically as functions of the cross flow velocity to quantify the effect of confinement on the flame geometry.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.10
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• pp.1012-1020
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• 2009

This research is focused on the experimental study of the noise induced by two-phase refrigerant flow in the evaporator. The two-phase flow in the evaporator has various flow patterns. The effects of two-phase flow pattern's characteristics on the noise of the evaporator are investigated experimentally. The experimental data shows that the generated noise is mainly related to the layout of the pipe and the certain two-phase flow patterns such as the churn and slug flow. Based on these results, we removed the unnecessary vertical pipe and changed the pipe diameter of the evaporator - inlet into small one in order to avoid the intermittent flow condition. The noise level of newly-designed inlet-pipe of the evaporator was measured experimentally by refrigerant-supplying equipment and compared with that of conventional one.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.12
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• pp.939-946
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• 2009

Wettability is a critical parameter in micro-scale two-phase system. Several previous results indicate that wettability has influential affect on two-phase flow pattern in a microchannel. However, previous studies conducted using circular microtube, which was made by conventional fabrication techniques. Although most applications for micro thermal hydraulic system has used a rectangular microchannel, data for the rectangular microchannel is totally lack. In this study, a hydrophilic rectangular microchannel was fabricated using a photosensitive glass. And a hydrophobic rectangular microchannel was prepared using silanization of glass surfaces with OTS (octa-dethyl-trichloro-siliane). Experiments of two-phase flow in the hydrophilic and the hydrophobic rectangular microchannels were conducted using water and nitrogen gas. Visualization of twophase flow pattern was carried out using a high-speed camera and a long distance microscope. Visualization results show that the wettability was important for two-phase flow pattern in rectangular microchannel. In addition, two-phase frictional pressure drop was highly related with flow patterns. Finally, Two-phase frictional pressure drop was analyzed with flow patterns.

• Journal of Power System Engineering
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• v.18 no.3
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• pp.79-86
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• 2014

Mixed convective vortex flow in the three-dimensional rectangular channel filled with high viscous fluid(Pr=909) is investigated computationally under various operating conditions. The Reynolds number is varied from 0 to $5{\times}10^{-1}$, the Rayleigh number from $10^3$ to $5{\times}10^4$. The three-dimensional governing equations are discretized using the finite volume method. The effects of Reynolds number and Rayleigh number are presented and discussed. From a parametric study, it is found that vortex flow pattern of mixed convection in rectangular channels can be classified into three flow patterns basically, but the new vortex flow structures containing wave rolls are found, which are affected by Rayleigh number and Reynolds number. From this results, we can draw a flow regime map to delineate various vortex flow patterns in the high viscosity fluid mixed convective flow.

• Journal of KIISE
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• v.43 no.2
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• pp.135-142
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• 2016

Visual analysis of spatiotemporal data has focused on a variety of techniques for analyzing and exploring the data. The goal of these techniques is to explore the spatiotemporal data using time information, discover patterns in the data, and analyze spatiotemporal data. The overall trend flow patterns help users analyze geo-referenced temporal events. However, it is difficult to extract and visualize overall trend flow patterns using data that has no trajectory information for movements. In order to visualize overall trend flow patterns, in this paper, we estimate continuous distributions of discrete events over time using KDE, and we extract vector fields from the continuous distributions using the gravity model. We then apply our technique on twitter data to validate techniques.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.231-232
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• 2008

The effect of n-electrode patterns on the current distribution in active region is investigated in GaN-based blue vertical light emitting diodes (VLEDs). A 3-dimension circuit model is adopted to analyze the current flow patterns in VLEDs. We had fabricated VLEDs having different n-electrode patterns, measured their current-voltage characteristics, and compared to the numerical simulation. It turns out that the current spreading in VLEDs is strongly dependent on the n-electrode pattern. Some design guidelines for n-electrode patterns to produce uniform current injection are presented.