• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.185-187
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• 2004

The electron concentration of ZnO thin film fabricated by pulsed laser deposition was controlled by varying oxygen gas pressure. The electron concentration of ZnO was increased from $10^{17}\;to\;10^{19}/cm^3$ as oxygen gas pressure increased from 20 mTorr to 350 mTorr. Ultraviolet(UV) intensity of photoluminescence of ZnO was controlled, too. UV intensity of ZnO was increased as oxygen gas pressure increased from 20 mTorr to 350 mTorr. The relation between electron concentration and UV intensity was investigated.

• Journal of Veterinary Clinics
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• v.21 no.3
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• pp.270-275
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• 2004

Anesthetic machines may be equipped with either a precision or nonprecision vaporizer. A precision vaporizer is designed to deliver an exact concentration of anesthetic agent. Goldman vaporizer is a low-flow, closed-circle circuit with a low resistance vaporizer, in circuit. Vaporizers used within circle system(VIC) are not usually temperature compensated and this is generally thought to be a disadvantage. As the volatile agent is vaporized, heat is extracted from the liquid and temperature decreases. This cooling of the liquid leads to a decrease in concentration of the anaesthetic agent delivered by the vaporizer. The purpose of this study is to examine the mechanical consistency of the delivery of isoflurane from Goldman vaporizer and precision vaporizer at various gas flow rates and temperatures. And we first studied isoflurane concentration according to room temperature changes delivered by a Goldman vaporizer and precision vaporizer using different gas flow. The room temperature of $15^{\circ}C,$ $20^{\circ}C,$ $28^{\circ}C$ and fresh gas flow rates of 0.5, 1.0, 1.5, 2.0, 3.0 l/min were used. The inspired agent concentration was measured using a Datex-Ohmeda multigas analyzer. As rose in room temperature, the isoflurane concentration of precision vaporizer approximated the dial setting. On the other hand, at a dial setting concentration of 5.0 percent the delivered isoflurane concentration of precision vaporizer was more than the dial setting in high temperature. The isoflurane concentration of precision vaporizer remained constant despite the increase in temperature. The isoflurane concentration of Goldman vaporizer was increased with rise in room temperature and decreased with rise in gas flow.

• The Korean Journal of Food And Nutrition
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• v.31 no.2
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• pp.308-312
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• 2018

Even though chlorine dioxide ($ClO_2$) is utilized in a pre-treatment due to its effective sterilizing activity for microorganisms and its safety for food, it has a limitation in maintaining freshness of the food product. In this study, a low-concentration $ClO_2$ gas was produced in a packaging form of air-permeable gel pack so that it could be released continuously over several days. The amount of $ClO_2$ gas emission and microbial inactivation effect against foodborne pathogens were measured during the release of $ClO_2$ gas. As a result of measuring the change of color in order to confirm whether the chlorine dioxide gas was eluted in the form of a sustained release, the yellowness was significantly higher at higher gel pack concentration and higher value during storage periods. The slow-released $ClO_2$ gel-pack showed clear inactivation effect against Escherichia coli and Staphylococcus aureus with 99.9% inactivation efficiency. As a result of measuring the sterilization effect of Listeria monocytogenes by the concentration of chlorine dioxide gas, the sterilization effect was increased as the concentration was increased. Therefore, the slow-released $ClO_2$ gel-pack is feasible to apply for industry usages.

• Journal of Environmental Health Sciences
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• v.30 no.5 s.81
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• pp.378-387
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• 2004

This study was carried to investigate the emission characteristics of mercury from domestic and industrial MSW (municipal solid waste) incinerator stacks. The mercury concentration levels of flue gas from 32 MSW incinerators stacks selected were above the criteria level ($5{\mu}g/S\;m^3$). MSWI facilities exceeding the criteria levels in Korea are due to the poor units comparison of combustion chamber(CC)-cyclone(CY)-stack. So, the mercury from MSW incinerators stack were suspected to contaminate the natural system unless the MSW incinerators were properly controlled. Mean-while, the relationship between mercury concentration and temperature of flue gas in MSW incinerator stacks were examined at two temperature ranges (Group A : $29.85{\sim}327.63^{\circ}C$, Group B : $446.9{\sim}848.15^{\circ}C$). The mercury concentration in flue gas with high temperature range was higher than that of flue gas with low temperature rage. This mean that the temperature of flue gas plays an important role in mercury control in MSW incinerator. The emission characteristics oi mercury was also evaluated by using the correlation matrix between the mercury and NOx, $PM_{10}$, moisture (MO.) at both low temperature and high temperature flue gas ranges. The mercury concentration was mainly affected by NOx, $PM_{10}$. moisture (MO.) at low temperature range, while the mercury concentration at high temperature flue gas was mainly affected by NOx, moisture (MO.). From these results, it was suggested that the temperature of cooling system and the air pollution control device should be properly regulated in order to control mercury of flue gas in MSWI incinerator.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.6
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• pp.95-101
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• 2002

There are many effective parameters to high concentration ozone generation. These parameters became very important elements should be considered before designing ozone generator. After designing, there are many peripheral parameters to greatly affect to high concentration ozone generation also. In this study, of many effective peripheral parameters on high concentration ozone generation, the effects of flow rate of inlet oxygen gas and some kinds of additional gases on ozone concentration were investigated As a result, when inlet oxygen gas was introduced at the range of 0.75［LPM］～2.00［LPM］ the highest ozone concentration of 71145［ppm］ was obtained at 1.25［LPM］. When the additional nitrogen gas was mixed to oxygen gas at the range of 0.0［vol%]～6.4［vol%］ the highest ozone concentration of 73135［ppm］ was obtained at 0.8［vol%］ of nitrogen gas. This showed 3［%］ increasing compared to the case of pure oxygen gas inlet. When the additional argon gas was mixed to oxygen gas at the range of 0.0［vol%］～6.4［vol%］ the highest concentration of 67288［ppm］was obtained at 0.8［vol%］of argon gas. This is decreased value compared to that of introducing the pure oxygen.

• Fire Science and Engineering
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• v.19 no.2 s.58
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• pp.69-74
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• 2005

A study of the utilization of inert gas generator(IGG) that generates a large amount of inert gas for the fire extinguishing equipment was performed. In this study, the fire extinction performance of gas generated from a 1GG which is implemented to a gas turbine was investigated. A simulated mixture gas of which composition is the same as that of the gas generated from ICG was used in all experiments. First, the extinction concentration was measured using a cup burner method. The extinction design concentration and the volume of extinction space was calculated by applying the obtained extinction concentration to a method recommended by NFPA 2001. In practical respects, the fire extinction performance of IGG-generated gas was confirmed through the fire suppression experiment within a $2m\times2m\times2m$ room.

• Journal of the Korean Ceramic Society
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• v.36 no.12
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• pp.1322-1326
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• 1999

In2O3 thick film gas sensor for detecting NOx gas of high concentration was fabricated by a screen printing technique. This work focussed on investigation of the change of sensitivity to NOx gas with firing temperatures of sensing layer and on improvement of the sensitivity by adding catalysts such as Al,. Ru, and SnO2 The cross sensitivites of sensor to CO, H2, CH4 and i-C4H10 gases were also examined under NO2 gas concentration of 200ppm Pure In2O3 gas sensor prepared at a firing temperature of 50$0^{\circ}C$ showed a maximum sensitivity to NOx gas at the operating temperature of 40$0^{\circ}C$ Al(0.004 wt%)-In2O3 sensor largely improved the sensitivities to both NO2 and NO gas and showed a superior selectivity compared with other gas sensors.

• Journal of the Korean Chemical Society
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• v.61 no.4
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• pp.139-142
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• 2017

Ethene ($C_2H_4$), which is produced in plants as they mature, was used to study its photoacoustic properties using photoacoustic spectroscopy. Detection of trace amounts, with $N_2$ gas, of $C_2H_4$ gas was also applied. The gas was tested in various conditions-temperature, concentration of the gas, gas cell length, and power of the laser- to determine their effect on the photoacoustic signal, the ideal conditions to detect trace gas amounts, and concentration of $C_2H_4$ produced by an avocado and a banana. A detection limit of 10 ppm was determined for pure $C_2H_4$. A detection of 5% and 13% (by volume) concentration of $C_2H_4$ was produced for a ripening avocado and banana, respectively, in closed space.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.2
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• pp.69-73
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• 2018

The power law is very important in gas sensing for the determination of gas concentration. In this study, the resistance of a gas sensor based on poly (3, 4-ethylenedioxythiophene) polystyrene sulfonate+graphene oxide composite was found to exhibit a power law dependence on hydrogen concentration at $150^{\circ}C$. Experiments were carried out in the gas concentration range of 30~180 ppm at which the sensor showed a sensitivity of 6~9% with a response and recovery time of 30s.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.6
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• pp.1-8
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• 2000

A new method of knock detection in SI engines, using a change of ion concentration in the combustion chamber, was developed. In order to measure in-cylinder ionization current, ionization probes were installed at spark plug and cylinder head of production engine. It was found that the electric current generated by ionized gas in core burned gas region of knocking cycle is between 2 and 10 times larger than that of normal cycle, because the burned gas temperature which is the dominant parameter of a change of ion concentration increases. However, a change of ionization current in boundary region of burned gas is relatively weak. Hence a change of ion concentration in core burned gas region can be used for knock detection.