• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.8
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• pp.761-766
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• 2010

The estimation method of the interchangeability in a partial premixed appliance about various compositions of natural gases using equivalent gases, experimentally. The results of the experiment in which equivalent gases were used compared with those obtained in experiments in which natural gases were used; Images of flames, lift-off limits, CO emissions, and incomplete combustion indices in KS standard for the domestic gas range were considered. From the comparison, it was observed that the length and color of the flame of the equivalent gases were almost the same as those of imported natural gases. Further, in the case of gases with Wobbe indices greater than 51 MJ/$m^3$, the KS standard for lifting limits was satisfied. Furthermore, in the case of gases with Wobbe indices less than 56.3 MJ/$m^3$, the CO mole fractions are in the range 95-100 ppm. Hence, the range of Wobbe indices 51-56.3 MJ/$m^3$ was proposed to be the range for interchangeability from the points of view of lifting limits and incomplete combustion, as prescribed in the domestic gas range in the case of imported natural gases.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.5
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• pp.54-59
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• 2011

Reliable starting capability of a gas turbine engine calls the engine industry's attention recently. So far the gas turbine engine performance researches have focused on the range between idle to Max rpm, but recent attention on the starting has brought interests in the range of "Sub-dile". As component characteristic maps are essential for the starting research, various kinds of studies have been doing and proposing ways to expand the existing maps toward sub-idle range. In this paper, previous studies were discussed and a new method suggested and validated.

• International Journal of Automotive Technology
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• v.8 no.6
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• pp.667-674
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• 2007

Various types of NOx storage catalysts for NGV's were designed, manufactured, and tested in this work on a model gas test bench. As in most of other studies on NOx storage catalyst, alkaline earth metal barium(Ba) was used as the NOx adsorbing substance. The barium-based experimental catalysts were designed to contain different amounts of Ba and precious metals at various ratios. Reaction tests were performed to investigate the NOx storage capacity and the NOx conversion efficiency of the experimental catalysts. From the results, it was found that when Ba loading of a catalyst was increased, the quantity of NOx stored in the catalyst increased in the high temperature range over 350. With more Ba deposition, the NOx conversion efficiency as well as its peak value increased in the high temperature range, but decreased in the low temperature range. The best of de-NOx catalyst tested in this study was catalyst B, which was loaded with 42.8 g/L of Ba in addition to Pt, Pd and Rh in the ratio of 7:7:1. In the low temperature range under $450^{\circ}C$, the NOx conversion efficiencies of the catalysts were lower when $CH_4$, instead of either $C_3H_6$ or $C_3H_8$, was used as the reductant.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.694-699
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• 2010

Reliable starting capability of a gas turbine engine calls the engine industry's attention recently. So far the gas turbine engine performance researches have focused on the range between idle to Max rpm, but recent attention on the starting has brought interests in the range of "Sub-dile". As component characteristic maps are essential for the starting research, various kinds of studies have been doing and proposing ways to expand the existing maps toward sub-idle range. In this paper, previous studies were discussed and a new method suggested and validated.

• Analytical Science and Technology
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• v.35 no.5
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• pp.197-204
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• 2022

A gas chromatography-mass spectrometric method was developed for determining 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT), 2-methyl-4-isothiazolin-3-one (MIT), 1,2-benzisothiazolin-3-one (BIT), 3-iodo-2-propynyl butyl carbamic acid (IPBC) and benzoic acid (BA) in household products. A 0.5 g sample was placed in a test tube and dissolved with 5 mL water, 5 mL methylene chloride and 1.0 mL methanol. The solution was extracted by ultra-sonication followed by mechanical shaking using the salting out effect. Under the established condition, the lowest quantification limits of all analytes were in the range of 0.04-10 mg/kg and their relative standard deviations were less than 8.0 %. The method was used to analyze 10 household products. As a result of analyzing 10 household products, MIT was detected in the range of 1.2-3.5 mg/kg in 3 of 10 samples, CMIT was detected in the range of 2.6-8.2 mg/kg in 3 of 10 samples, and BA was detected in the range of 5.0-15 mg/kg in 4 of 10 samples. Meanwhile, BIT and IPBC were not detected in any of the products. It has been shown that this method can be used for the simultaneous determination of biocides with various physical and chemical properties in household products.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.12
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• pp.1715-1721
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• 2002

Numerical analysis was conducted to characterize the gas flow field and particle deposition on a horizontal freestanding semiconductor wafer under the laminar flow field at vacuum environment. In order to calculate the properties of gas, the gas was assumed to obey the ideal gas law. The particle transport mechanisms considered were convection, Brownian diffusion and gravitational settling. The averaged particle deposition velocities and their radial distributions fnr the upper surface of the wafer were calculated from the particle concentration equation in an Eulerian frame of reference for system pressures of 1 mbar~1 atm and particle sizes of 2nm~10$^4$ nm(10 ${\mu}{\textrm}{m}$). It was observed that as the system pressure decreases, the boundary layer of gas flow becomes thicker and the deposition velocities are increased over the whole range of particle size. One thing to be noted here is that the deposition velocities are increased in the diffusion dominant particle size range with decreasing system pressure, whereas the thickness of the boundary layer is larger. This contradiction is attributed to the increase of particle mechanical mobility and the consequent increase of Brownian diffusion with decreasing the system pressure. The present numerical results showed good agreement with the results of the approximate model and the available experimental data.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.285-288
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• 1996

The electronic operation of the gas discharge tube is controlled by the electrical energy as sinusoidal waveform in arbitrary frequency range, or as a sequence of pulses at a wide range of duty cycle, the gas composition, the kind of electrode and the vessel geometry. In this paper, the pulsed mode operated gas discharge tube is composed with mixed gas of IIg-Ne ( 10 Torr ), in the tube of 15.0 mm outer diameter and has variable color from red to blue with changing frequency and pulse width in high voltage. As increasing pulse width and frequency in the gas discharge tube, the phenomenons that the electron temperature in the positive column increases and the radiation from atoms of higher upper state energy levels increases, exist. The color have the locus from red (0.4972, 0.3128) to blue (0.2736, 0.2619) in CIE chromacity diagram with increasing pulse width and frequency. The changing method of pulse width and frequency has been shown to be suitable for the luminous color control.

• Journal of Sensor Science and Technology
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• v.25 no.6
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• pp.423-430
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• 2016

This study used a single metal oxide semiconductor (MOS) sensor to classify the major odorous gases hydrogen sulfide ($H_2S$), ammonia ($NH_3$) and toluene ($C_6H_5CH_3$). In order to classify these odorous substances, the voltage on the MOS sensor heater was gradually reduced in 0.5 V steps 5.0 V to examine the changes to the response by the cooling effect on the sensor as the voltage decreased. The hydrogen sulfide gas showed the highest sensitivity compared to odorless air under approximately 2.5 V and the ammonia and toluene gases showed the highest sensitivity under approximately 5.0 V. In other words, the hydrogen sulfide gas reacted better in the low temperature range of the MOS sensor, and the ammonia and toluene gases reacted better in the high-temperature range. In order to analyze the response characteristics of the MOS sensor by temperature in a pattern, a two-dimensional (2D) x-y pattern analysis was introduced to clearly classify the hydrogen sulfide, ammonia, and toluene gases. The hydrogen sulfide gas was identified by a straight line with a slope of 1.73, whereas the ammonia gas had a slope of 0.05 and the toluene gas had a slope of 0.52. Therefore, the 2D x-y pattern analysis is suggested as a new way to classify these odorous substances.

• Journal of Power System Engineering
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• v.6 no.4
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• pp.23-29
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• 2002

This paper is studied to investigate the effect of slits and swirl vanes on the main flow fields of a gun-type gas burner through X-Y plane and Y-Z plane respectively by using X-probe from hot-wire anemometer system. This experiment was carried out with flow rate $450{\ell}/min$ in respective burner models installed in the test section of a subsonic wind tunnel. The burner models with only slits and only swirl vanes respectively were made by modifying original gun-type gas burner. The fast jet flow spurted from slits played a role such as an air-curtain because it encircled rotational flow by swirl vanes and drives mixed main flow to axial direction. As a result, the gun-type gas burner had a wider flow range up to about Y/R=1.5 deviated from slits and maintains a comparatively large velocity in the central part of burner within the range of about X/R=2.5. Therefore, it was very desirable that swirl vanes were installed within slits in gun-type gas burner in order to control the main flow fields effectively.

• Korean Journal of Hazardous Materials
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• v.6 no.2
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• pp.95-104
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• 2018

Gas-liquid bubble column reactors are extensively used in industrial processes. A detailed knowledge of bubble size distribution is needed for determining the mass transfer in gas-liquid film. Experimental data on bubble size distribution and liquid-side mass transfer coefficient($k_L$) were used to calculate the estimated time to saturation in bubble column reactor. Also, the gas flux was evaluated to the liquid-side mass transfer coefficient($k_L$) and solubility data for hydrogen sulfide($H_2S$) and chlorine($Cl_2$) absorption into water. Simulation results show that $H_2S$ absorption time to 50 % of saturation concentrations are 611 sec and 1,329 sec when bubble diameters are 0.5 mm and 4.5 mm, while absorbing 1 % $H_2S$ gas. In case of $Cl_2$, absorption time range 657 to 1,400 sec when bubble size range 0.5 mm to 4.5 mm, while absorbing 1 % $Cl_2$ gas. Calculated simulation results can be used in the design of emergency relief bubble reactors.