• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.9-12
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• 2010

This paper discusses experimental data for the assessment of flow discharging characteristics of double swirl coaxial injectors operating at fuel-rich conditions. Combustion tests employing liquid oxygen and kerosene (Jet A-1) were conducted and a discharge coefficient was utilized for defining flow characteristics. A mass flow rate, a pressure, and a temperature were measured to estimate discharge coefficients. Fuel injectors revealed a fixed value of a discharge coefficient regardless of matched LOx injector design, chamber pressure, and mixture ratio. However, oxidizer injectors showed varying discharging coefficients depending on chamber pressure and mixture ratio. Flame structure variations seem to affect flow discharging characteristics of the oxidizer side.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.49-53
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• 2009

The paper presents the results of the experimental study about flow discharge characteristics of double swirl coaxial injectors for a liquid rocket engine. Flow discharge characteristics of injectors become one of critical design issues for LRE combustion devices. Tap water and liquid oxygen/kerosene were used for ambient and hot firing tests, respectively. A combustion discharge coefficient varies depending on a mixture ratio and a recess ratio, and magnitudes of the variations are different with respect to injector shapes and operating conditions. The variation of a combustion discharge coefficient with a LOx injector is considered to result from flame structure changes due to physical property changes.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.5
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• pp.112-120
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• 2008

This study has been conducted to investigate the characteristics of flow field and discharge valve motion in a rotary compressor. In this study, a transient three-dimensional numerical analysis using FSI(Fluid-Structure Interaction) model has been employed to analyze the interaction between the discharge valve and the refrigerants in the rotary compressor. It has been observed that two peaks have appeared in the displacement of the discharge valve. The maximum displacement of the discharge valve has been found to be located at the second peak. Also, the input pressure of the refrigerants has been compared with the pressures of the muffler passage and the compressor outlet in the rotary compressor. The pressure has decreased along the pathway in the rotary compressor. And the volume flow rates obtained from the current numerical study have been compared with the experiment at data to verify the validity of the present numerical study. This study may supply the fundamental data for the design of rotary compressors.

• Journal of the Korean Geotechnical Society
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• v.34 no.10
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• pp.51-60
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• 2018

Recently, a cylindrical cut-off wall was proposed as a new technology for temporary offshore works. The cut-off wall has a cylindrical shape, so seepage analyses are necessary to analyze the effect of wall shape. In this study, a numerical analysis was performed to investigate the seepage discharge inside cut-off walls. The numerical modeling was verified by comparing with the theoretical solution for the cofferdam with double sheet piles. Two different flow conditions were compared between 2-dimensional flow and axisymmetric flow. The results showed that the discharge of the axisymmetric flow was about 1.55 times larger than that of 2-dimensional plain flow. A parametric study was carried out by varying wall radius, penetration depth of the wall, and total head difference between in and outside of the wall. The discharge decreased with the increase of the penetration depth and the wall radius. Finally, the design equations were suggested to determine the discharge for the preliminary design of the cylindrical cut-off wall.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.10
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• pp.500-505
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• 2002

In this paper, fluorescent discharge type ozonizer has been designed and manufactured. Ozone discharge and generation characteristics have been investigated in accordance with a sort of internal electrodes, output voltage of power supply, air flow rate and discharge power. Air has been used as the supplied gas of the ozonizer In this paper, when disuse fluorescent lamp was used as an internal electrode. Air flow rate was varied from 2[1/min] to 10[1/min]. The maximum ozone concentration and yield were 3495[ppm] and 23.4[g/kWh] respectively at 2[1/min] air flow rate and 35.2[W] input power. Illumination was appeared as 5[lx] within 15[cm] from external electrode. Whorl fluorescent discharge type ozonizer was used, air flow rate was also varied from 2[1/min] to 10[1/min]. At this moment, the maximum ozone concentration and yield were 2824[ppm] and 21.7[g/kWh] respectively at 2[1/min] air flow rate and 30.5[W] input power. Illumination was also appeared as 5[lx] within 15[cm] from external electrode like used fluorescent lamp.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.106-114
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• 2003

The pressure ripple in the delivery port is caused by flow ripple, which is induced by variation of pumping chamber volume. The other reason is the reverse flow from the outlet volume produced by pressure difference between pumping chamber and outlet volume, when the pumping chamber is connected with the outlet volume. In this study, a mathematical model is presented for analyzing discharge pressure ripple, which includes vane detachment, cam ring movement , and fluid inertia effects in V-groove in the side plate. From the analysis and experiment, it was found that V-groove on the side plate, coefficient of spring supporting the cam ring, and average discharge pressure are the main factors of discharge pressure ripple in variable displacement vane pump. The theoretical results, provided in this study, were well agreed with experimental results. The analytical model to estimate the magnitude of pressure ripple in this study is expected to be used f3r the optimal design of the variable displacement vane pump.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1376-1379
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• 2007

The effects of the MgO fabrication process on the properties of AC-PDPs were examined. MgO films were deposited by e-beam evaporation with various substrate temperatures and oxygen flow rates. MgO films were analyzed by XRD, CL and ellipsometer. Panel properties such as luminance, efficiency, discharge voltage and discharge delay time were measured with test panels. MgO films with higher temperature, smaller oxygen flow rate showed shorter discharge delay time. Also they showed smaller XRD peak intensity. These results revealed that the discharge delay time was strongly influenced by temperature and oxygen flow rate of the MgO fabrication process.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.652-657
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• 2001

Computational work using the axisymmetric, compressible, Navier-Stokes Equations is carried out to predict the discharge coefficient of mass flow through a micro-critical nozzle. Several kinds of turbulence models and wall functions are employed to validate the computational predictions. The computed results are compared with the previous experimented ones. The present computations predict the experimental discharge coefficients with a reasonable accuracy. It is found that the standard $k-\varepsilon$ turbulence model with the standard wall function gives a best prediction of the discharge coefficients. The displacement thickness of the nozzle wall boundary layer is evaluated at the nozzle throat and is well compared to a prediction obtained by an empirical equation. The resulting displacement thickness of the wall boundary layer is about 2% to 0.6% of the diameter of the nozzle throat for the Reynolds numbers of 2000 to 20000.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.379-380
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• 2008

Recently, ozone is utilized in various fields and its needs are expanding. In this paper, glass and ceramic plate tyre ozonizer have been fabricated to investigate discharge parameter(input power, flow rate of supplied gas, electrode form, etc.) effect to discharge. And the conditions of discharge parameter have been investigated for optimum ozone generation. Ozone concentration is continuously increased with increasing input power for same discharge space, and ozone yield is also increased until maximum point after that it is saturated. Ozone concentration is inversely proportional to flow rate of supplied gas but ozone generation and ozone vield characteristics are improved.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1090-1092
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• 1999

In this paper, multi discharge type ozonizer has been designed and manufactured. The of ozonizer is equipped with three electrodes(central electrode of screw shape, internal electrode and external electrode). This paper describes the following two characteristics: (1) The characteristics of discharge with variation of output voltage of AC H.V source, flow rate of oxygen supplied gas and discharge voltage. (2) The characteristics of ozone generation by varying flow rate and discharge power.