• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.323-326
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• 1998

The current-voltage characteristic have been measured in a gas stabilized DC arc generated in a non-transferred arc plasma torch operating on a mixture of argon and nitrogen. Relation between voltage and current to these arcs has been examined by plasma power and current under different flow rates and gas mixture ratios. Firstly, the voltage and current of arc plasma used argon was measured and secondly, in argon-nitrogen mixed gas regime, the flow rate of nitrogen was increased slowly. When the flow rate of nitrogen was increased, electrode drop of potential was increased.

• 한국전산유체공학회:학술대회논문집
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• 2009.11a
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• pp.129-134
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• 2009

In the present study, the characteristic of flow distribution in the channel of a plate heat exchanger is investigated numerically. In order to accomplish the efficient and fast analyses of the flow characteristics in the channel, a semi-microscopic analysis has been performed using a porous media model. For semi-microscopic analysis using porous media, the flow resistance coefficients are obtained through the result of pressure drop in the experimental data. The results showed that the variation of mass flow rate, geometry and chevron angle strongly depend on the flow distribution in the channel. Particularly, the chevron angle is most important factor for uniform flow distribution.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.269-274
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• 2008

The present study has been studied on a thermal and flow characteristic of the microchannel waterblock with flow distributions in each channels. Results of a numerical analysis using the CFX-11 are compared with results of an experiment. Numerical analysis and experiment are conducted under a heat transfer rate of 150W, inlet temperature of $20^{\circ}C$ and mass flow rates of $0.7{\sim}2.0\;kg$/min. Base temperature and pressure drop are investigated with standard deviations of mass flow rates in each channels of samples at 0.7 kg/min.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.229-234
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• 2003

As electrorheological fluid(ER fluid) has a characteristic that apparent viscosity varies when electric field applied, so rheological characteristic(yield stress & viscosity) changes in proportion to the electric field applied and the response time is very short within a few miliseconds . In case of using ER fluid for journal bearing as lubricant, it is estimated that it's possible to realize very effective journal bearing system that is not complicate and has a very quick response time. It is necessary to examine the influence of rheological characteristic that varies with electric field applied on bearing characteristic to apply ER fluid to journal bearing, however there are few studies for about that. As for the journal bearing, it comes under high shear flow mode that has shear rate range of $10^3\~10^4s^{-1}$ because rotational speed is very high and clearance is small. But most of the studies for about ER fluid issued until now is about the range of $10\~10^2s^{-1}$. So, there are a lot of difficulties to understand the characteristic offish shear flow mode and furthermore it is restricted to make an experiment for about the characteristic of ER fluid because of the limitation of experimental equipment. The equipment was prepared to make an experiment lot high shear flow mode that has the range of $10^3\~10^4s^{-1}$ using ER fluid that is composed of silicon oil with dispersed particle of starch. Using the above system, the fluid characteristic of ER fluid was studied.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.119-122
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• 2009

The purpose of this study is to design of film-cooling ring for the small thrust rocket engine using green propellants(Hydrogen peroxide and kerosene). Cold flow test was carried out to measure the mass flow rate and atomizing characteristic. Required mass flow rate was obtained from thermal analysis of the engine, and measured flow rate 42.25g/s was in the range of permissible coolant flow rate. With the same mass flow rate, cooling ring with more hole and high velocity shows better spray pattern. The result of thermal analysis, cooling ring has enough cooling performance.

• Journal of Environmental Science International
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• v.17 no.9
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• pp.957-968
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• 2008

The purpose of this study is to analyze the characteristics of hydraulic behavior of the natural channel flow according to the temporal classification mode, and thus propose the hydraulic analysis method for future channel design. For analysis, the temporal flow characteristics of the channel section was divided into the steady flow and the unsteady flow. For hydraulic analysis, the HEC-RAS model, which is a one-dimensional numerical analysis model, and the SMS-RAM2 model, which is a two-dimensional model, were used and the factors used for analysis of hydraulic characteristics were flood elevation and flow rate. The flow state was analyzed on the basis of the one-dimensional steady flow and unsteady flow for review. In the unsteady flow analysis the flow rate changed by $(-)0.16%{\sim}(+)0.26%$, and the flood elevation varied by $(-)0.35%{\sim}(+)0.51%$ as compared to the values in the steady flow analysis. Given these results, in the one-dimensional flow analysis based on the unsteady flow the flood elevation and flow rate were greater than when the analysis was done on the basis of the steady flow. The flow state was analyzed on the basis of the two-dimensional steady flow and unsteady flow. In the unsteady flow analysis the flow rate varied by $(-)0.16%{\sim}(+)1.08%$, and the flood elevation changed by $(-)0.24%{\sim}(+)0.41%$ as compared to the values in the steady flow analysis. Given these analysis results, in the two dimensional flow analysis based on the unsteady flow, the flood elevation and flow rate were greater than when the analysis was done on the basis of the steady flow.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.345-350
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• 2003

The inside of EMU is supplied with the cooling air from air-conditioner and the fresh air from exterior through the air-conditioner duct which is one of the air conditioning system. The shape of air-conditioner duct is a major factor in determining the air-conditioning efficiency, thermal comfort and energy efficiency. Therefore, this study is to understand the flow characteristics in the air-conditioner duct by three dimensional numerical simulation. The air-conditioner duct was calculated for the design volume flow rate, $2,726\;m^3/h/unit$. From the result of calculation and measurement, the velocity at diffuser outlet presented good agreement in general. [n this present study, the calculation was also performed for three volume flow rate(1,800, 2,200, 3,000 $m^3/h/unit$) and total pressure characteristic curve with volume flow rate was presented.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.8
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• pp.574-581
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• 2008

The characteristics of combustion and flow for a lean premixed flame in lab-scale gas turbine combustor was studied through experiment and numerical analysis. From the experiment, flame structure and heat release rate were obtained from OH emission spectroscopy. Qualitative comparisons were made line-integrated OH chemiluminescence image and abel-transformed one. NOx analyzer was implemented to get the characteristic of NOx exhaust from the combustor. From the numerical analysis, the thermal distribution and characteristic of recirculation zone with the change of fuel-air mixing degree, the characteristic of methane distribution with equivalence ratio in the combustor respectively. Total heat release rate is increased with increasing equivalence ratio. Thermal Nox is reduced with increasing fuel-air mixing degree. Increasing equivalence ratio results in the decrease of the size of reaction zone and alteration of the position of the reaction zone into the entrance of the combustor.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.5
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• pp.97-103
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• 2011

This study is numerical analysis on flow characteristic in a standard cyclone dust separator. The cyclone dust separator is widely used in a industrial applications as a method for dust removed from gases. In cyclone chamber, a very complex flow field is formed, involving the interaction between highly swirling velocity and turbulent field. Numerical analysis with computational fluid dynamics(CFD) was carried out to investigate the working fluid that flow into cyclone dust separator. Helical entry type was increasing flow rate compared with tangent entry type. And according to increasing pressure difference was increased fan power. But, helical entry type was high performance dust separator, in comparison with tangent entry type.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.5
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• pp.67-75
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• 2013

This study is flow analysis on the smoke collector in smoking room. The smoke collector for improving impure air at smoking area is analyzed and the inner flow filed in smoke collector is confirmed on the study result. The velocity with pressure distribution according to suction flow rate at filter entrance is also compared. Pressure characteristic and pressure resistance coefficient are analyzed according to flow analysis result for each other filter. The pressure drop of about 15 Pa occurs at the normal driving mode to strainer inlet from HEPA filter outlet. On the other hand, the pressure drop about 44% increases at turbo mode.