• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.323-326
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• 2007

In this paper, the basic experiment, electrolytic cell design and basic manufacturing have been made to interpret the characteristics of Hydrogen-Oxygen-Gas-Generator. As for the detailed matters, the data research on basic technology on Hydrogen-Oxygen-Gas and analysis on characteristics of Hydrogen-Oxygen-Gas from basic experiment. Also the experiment of characteristics and comparative evaluation between constant current source using SCR converter from existing method and constant current source using new phase shift PWM control method converter. As results when it has injected constant DC current, we has compared Gas quantities by variable ripple frequencies using phase shift PWM control method converter. Therefore, in linear region, it has not different Gas quantities by constant DC current and by phase shift PWM control method converter. Also, it has increased Gas quantities wilder linear region when put ripple frequency at saturation region. Through, Gas quantities and input rower, it has acquired higher input power per Gas quantities at put pulse current. Therefore, when designing converter or inverter for electrolysis, which has ripple current.

• Journal of Sensor Science and Technology
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• v.16 no.1
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• pp.39-43
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• 2007

This paper presents characteristics of surface acoustic wave (SAW) gas sensor for detecting volatile gases such as acetone, methanol, and ethanol by measuring phase shift of output signal. A delay-line by combining with a center frequency of 200 MHz was fabricated on S-T Quartz substrates. Using gas chromatography column, the selectivity of the SAW gas sensor were introduced. Experimental results, which show the phase change of output signal under the absorption of volatile gas on sensor surface, were presented. This SAW gas sensor system may be well suited for a high performance electronic nose system.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.301-306
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• 1996

To predict the average liquid level under the condition of the countercurrent stratified two-phase flow in a pipe, an analytical model has been suggested. This is made by introducing the interfacial level gradient into the liquid-phase and the gas-phase momentum equations. The analytical method for the gas-phase pressure drop calculation with f$_i$ $\neq$ f$_G$ has also been described using the liquid level prediction model developed in the present study.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.181-182
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• 2003

A preconditioned numerical method for gas-liquid to-phase flow is applied to solve cavitating flow. The present method employs a density based finite-difference method of dual time-stepping integration procedure and Roe's flux difference splitting approximation with MUSCL-TVD scheme. A homogeneous equilibrium cavitation model is used. The method permits simple treatment of the whole gas-liquid two-phase flow field including wave propagation, large density changes and incompressible flow characteristics at low Mach number. By this method, two-dimensional internal flows through a venturi tuve and decelerating cascades are computed and discussed.

• Journal of the Korean Society of Tobacco Science
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• v.29 no.2
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• pp.146-151
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• 2007

Gas phase and particulate phase radicals in mainstream cigarette smoke were determined Electron Spin Resonance(ESR) spectroscopy. The free radicals in particulate phase have been investigated by benzene extract of Cambridge Filter Pad containing the smoke condensate. Spin trapping method in conjunction with ESR was used to investigate free radicals in the gas phase of cigarette smoke. Several analytical experiments were conducted in order to determine the optimal conditions for maximum signal intensities and reproducibility of results. All the tests were optimized and normalized using the University of Kentucky 2R4F reference cigarette. The optimal conditions were 0.6 mL for analysis volume of ESR, $4{\sim}5\;mL$ for collection volume of spin-adducts, and PBN for quantification of free radicals in gas phase. The radical levels of Kentucky 2R4F cigarettes were found $2.18{\times}10^{14}\;spins/cig.$ and $2.10{\times}10^{15}\;spins/cig.$ in gas phase.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.5
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• pp.619-629
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• 1998

An experimental work was conducted to investigate a feasibility of simultaneous measurement of gas-liquid two-phase flowrates with double orifice plates using air and water. The tests were carried out under the atmospheric pressure and at the ambient temperature using two different tube sizes. Qualities of an air-water flow in the present study have values less than 0.1 and thus the mixed flow showed bubbly, plug, slug flow regimes. The probability density function (PDF) and the power spectral density function (PSDF) of the instantaneous pressure drop traces for the flow regimes were obtained. It is found that some distinctive features exist in the distribution of these functions, depending upon the two-phase flow pattern. The time-averaged value of the instantaneous pressure drop increases with increasing gas and liquid flowrates, showing a single-valued function for the total mass flowrate and the quality. It is also found that the two-phase discharge coefficient exhibits a consistent trend for variation of dimensionless parameters such as the superficial velocity ratio and the gas Reynolds number. The results indicate that simultaneous measurement of two-phase flowrate may be possible based upon a statistical analysis of the instantaneous pressure drop curves monitored using double orifice plates.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.10
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• pp.1327-1339
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• 1999

Characteristics of two-phase flow and heat transfer were numerically investigated in a submerged gas Injection system. Effects of both the gas flow rate and bubble size were investigated. In addition, heat transfer characteristic and effects of heat transfer were investigated when temperature of the injected gas was different from that of the liquid. The Eulerian approach was used for the formulation of both the continuous and the dispersed phases. The turbulence in the liquid phase was modeled by the use of the standard $k-{\varepsilon}$ turbulence model. The interphase friction and heat transfer coefficient were calculated by means of correlations available in the literature. The turbulent dispersion of the phases was modeled by introducing a "dispersion Prandtl number". The plume region and the axial velocities are increased with increases in the gas flow rate and with decreases in the bubble diameter. The turbulent flow field grows stronger with the increases in the gas flow rate and with the decreases in the bubble diameter. In case that the heat transfer between the liquid and the gas is considered, the axial and the radial velocities are decreased in comparison with the case that there is no temperature difference between the liquid and the gas when the temperature of the injected gas is higher than the mean liquid temperature. The results in the present research are of interest in the design and the operation of a wide variety of material and chemical processes.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.202-208
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• 2006

The purpose of this research is to model numerically the turbulent gas-particle flows in a rectangular chamber using Eulerian-Eulerian Method. A computer code using the ${\kappa}-{\varepsilon}-Ap$ two-phase turbulence model is developed for the numerical study. This code and the Eulerian multiphase model in FLUENT were used for the numerical simulations of the two-phase flow in a rectangular chamber. The numerical results calculated by the two different turbulent gas-particle codes have shown that the ${\kappa}-{\varepsilon}-Ap$ model results in a stronger diffusion of the flow momentum in the gas-particle turbulence interaction than the Eulerian multiphase model in FLUENT.

• Journal of Environmental Science International
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• v.1 no.2
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• pp.105.1-113
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• 1992

The present study was performed to develop the removal system of the offensive gases, including hydrogen sulfide of acid gas, ammonia or amice of base gas, from the nightsoil treatment plant. In order to remove the offensive gases, the Fe-EDTA system liquid phase catalytic oxidation method with the bubble lift column reactor was employed. From the results obtained, it was confirmed that the offensive gases can be deodorized simultaneously and also hydrogen sulfide of acid gas, ammonia of base gas completely removed at pH 6.45. In addition, as input gases feed rate the efficiency of acid gas did not change but the efficiency of base gases decreased to approximately 90 % at pH 6, 0. From the result of particle size analyzer, it was found that the particle sizes including sulfur and other impurites grew up to $21{\mu}m$ over 72hour reaction time.

• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.187-194
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• 2005

For the analysis of compressible multi-phase and real gas flows, characteristic form of Roe's Riemann solver was derived using real gas equation of state. It was extended to multi component reactive system considering variable specific heat. From this study, it is known that some correction should be made for the use of existing numerical algorithm. 1) Sonic speed and characteristic variable should be corrected with real gas effect. 2) Roe's average was applicable only with the assumption of constant properties. 3) Artificial damping term and characteristic variables should be corrected but their influences may not be significant.