• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.491-494
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• 2008

The hydrogen fuel and fuel cell which have high energy efficiency and low pollutant emission are getting interest as an alternative energies due to the fossil fuel exhaust, green house effect and atmospheric pollutant problems. The hydrogen gas is very effective as an alternative energy. But, if it is leaked into the air it forms the mixed gas with the air then the danger of the explosion is risen up. So, the secure the safety is mostly important. In this research, to detect the leakage of the hydrogen rapidly, added the odorant materials which don't include the sulfur component into the hydrogen gas and researched on the effect of each odorant on the performance of the fuel cell. As the results, setting the cumulation electric power on the basis and comparing the pure hydrogen, 2,3-Butanedione 5ppm mixed gas 86.1%, 5-Ethylidene-2-Norbornene 17ppm mixed gas 88.2%, Isovaleraldehyde 10ppm mixed gas 74.8%, Ethyl Isobutyrate 2.2ppm mixed gas 93.5% of performance was shown.

• Environmental Engineering Research
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• v.18 no.3
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• pp.191-197
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• 2013

Republic of Korea announced the reduction target to be around 30% of business as usual greenhouse gas emissions by 2020. College campuses were ranked at the 5th of high energy consumption areas in the building sectors. Target management scheme was designed to set greenhouse gas emissions target including several college campuses. Previous studies showed the amount of greenhouse gas emissions with several assumptions such as the applications of renewable energy systems and light emitting diode lamps, etc. Long-range Energy Alternatives Planning model was utilized to simulate future greenhouse gas emissions. This study sets standard model labs for energy saving action programs by applying guidance studies. It has been deduced that energy saving action programs was responsible for reducing 949.5 kWh for each standard model lab and the total reduction of all 59 model labs in the Engineering College building has been calculated to 56,020.5 kWh. The objective of the study is to provide guidelines on standard model laboratory for greenhouse gas emissions reduction on the campus.

• Korean Journal of Human Ecology
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• v.20 no.6
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• pp.1153-1165
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• 2011

Decision making for gas boiler consumers depends on the characteristics of products such as the price and quality as well as the brand image. Although a gas boiler is a high involvement product in terms of price, in fact, it is a low involvement product which is greatly affected by installers. This study examined variables which affect the level of satisfaction and repurchase intention by surveying about 1,000 housewives through an on-line questionnaire. The results were as follows: first, gas boiler users' general knowledge of gas boilers showed a correct-answer rate of 54.5%. The average satisfaction score of product quality (mean=5.61 out of 7) was higher than that of the satisfactionscore of the company's service (mean=5.46). Second, the level of repurchase intention was above the mid-point (mean=4.72). Multivariate regression found that product satisfaction, service satisfaction, household size, and information sources explained repurchase intentions for gas boilers to be about 50.7%. Gas boiler marketers should pay attention to the survey result in that the level of repurchase intention depends mainly on both consumer satisfaction and information sources.

• Journal of Surface Science and Engineering
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• v.54 no.5
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• pp.260-266
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• 2021

Synthesizing low-dimensional structures of oxide semiconductors is a promising approach to fabricate highly efficient gas sensors by means of possible enhancement in surface-to-volume ratios of their sensing materials. In this work, vertically aligned zinc oxide (ZnO) nanorods are successfully synthesized on a transparent glass substrate via seed-mediated hydrothermal synthesis method with the use of a ZnO nanoparticle seed layer, which is formed by thermally oxidizing a sputtered Zn metal film. Structural and optical characterization by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy reveals the successful preparation of the ZnO nanorods array of the single hexagonal wurtzite crystalline phase. From gas sensing measurements for the nitrogen dioxide (NO₂) gas, the vertically aligned ZnO nanorod array is observed to have a highly responsive sensitivity to NO₂ gas at relatively low concentrations and operating temperatures, especially showing a high maximum sensitivity to NO₂ at 250 ℃ and a low NO₂ detection limit of 5 ppm in dry air. These results along with a facile fabrication process demonstrate that the ZnO nanorods synthesized on a transparent glass substrate are very promising for low-cost and high-performance NO₂ gas sensors.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.5
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• pp.523-531
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• 2021

Vietnam's Oil and gas industry make a significant contribution to the Gross Domestic Product of Vietnam. The ongoing COVID-19 pandemic has hit every industry hard, but perhaps the one industry which has taken the biggest hit is the global oil and gas industry. The purpose of this article is to examine how the COVID-19 pandemic affects the share price of the Vietnam Oil and Gas industry. The event study method applied to Oil and Gas industry index data around three event days includes: (i) The date Vietnam recognized the first patient to be COVID-19 positive was January 23, 2020; (ii) The second outbreak of COVID-19 infection in the community began on March 6, 2020; (iii) The date (30/3/2020) when Vietnam announced the COVID-19 epidemic in the whole territory. This study found that the share price of the Vietnam Oil and Gas industry responded positively after the event (iii) which is manifested by the cumulative abnormal return of CAR (0; 3] = 3.8% and statistically significant at 5 %. In the study, event (ii) has the most negative and strong impact on Oil and Gas stock prices. Events (i) favor negative effects, events (iii) favor positive effects, but abnormal return change sign quickly from positive to negative after the event date and statistically significant shows the change on investors' psychology.

• Journal of Powder Materials
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• v.19 no.2
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• pp.110-116
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• 2012

This study investigated the effects of annealing environment for the densification and purification properties of pure titanium coating layer manufactured by cold spraying. The annealing was conducted at $600^{\circ}C$/1 h and three kinds of environments of vacuum, Ar gas, and $5%H_2+Ar$ mixture gas were controlled. Cold sprayed Ti coating layer (as sprayed) represented 6.7% of porosity and 228 HV of hardness, showing elongated particle shapes (severe plastic deformation) perpendicular to injection direction. Regardless of gas environments, all thermally heat treated coating layers consisted of pure ${\alpha}$-Ti and minimal oxide. Vacuum environment during heat treatment represented superior densification properties (3.8% porosity, 156.7 HV) to those of Ar gas (5.3%, 144.5 HV) and $5%H_2+Ar$ mixture gas (5.5%, 153.1 HV). From the results of phase analysis (XRD, EPMA, SEM, EDS), it was found that the vacuum environment during heat treatment could be effective for reducing oxide contents (purification) in the Ti coating layer. The characteristic of microstructural evolution with heat treatment was found to be different at three different gas environments. The controlling method for improving densification and purification in the cold sprayed Ti coating material was also discussed.

• Journal of Energy Engineering
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• v.24 no.1
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• pp.51-57
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• 2015

The purpose of this study is to verify the performance of a static mixer for mixing of biogas and town gas by numerical analysis and demonstration test. The reason for designing a static mixer is that there is a need to mix town gas with biogas when there is less production of biogas in biogas sites. Non-uniformity in the outlet section was calculated for investigating the performance of a static mixer. Non-uniformity was based on the mole fraction of methane in a mixture of biogas and town gas. Low non-uniformity means that biogas and town gas are mixed well through this static mixer. Also, pressure drop at the outlet section of a static mixer was calculated. The pressure drop is less than 0.2% in this static mixer. This static mixer is suitable for applying to a 5MW bio-gas turbine through the demonstration test in the field.

• Journal of the Korean Ceramic Society
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• v.34 no.10
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• pp.1009-1014
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• 1997

Ammonia gas was blown into the solution of zirconium ion to induce precipitation of supersaturated zirconium ion at gas-liquid interface with increase in pH. The influence of pH on the phase and particle size of precipitate and calcined powders has been investigated. At pH 4.5 of zirconium solution, maximum yield of 98.7% was obtained. Above pH 4.5, there was no more increase of yield. Above pH 5.5, large aggregates consisting of primary particles were observed in precipitate and calcined powders. At pH 4.5, almost aggregate-free fine spherical zirconia powders were obtained.

• Economic and Environmental Geology
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• v.33 no.3
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• pp.239-246
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• 2000

The 3.5kHz sub-bottom profiling was carried out over both Gwangyang Bay and the Yeo Sound . High -resolution digital images of uppermost sediment layers are obtained from the field data which were originally recorded in analog mode. Most prominent feature along the acoustic profiles is the chaotic reflections which imply the presence of shallow gas within the silty sediments. In the western part of Gwangyang Bay, the gas-charged sediments are assoicated with the acoustic turbidity of the blanket type. Across the Seomjin Delta in the eastern part of Gwangyang Bay, the gas-charged seismic facies are observed just beneath the sea bottom. In the western Yeoul Sound , the gassy seiments occur widely , whereas it is rare in the eastern counterpart with the <30-m-deep channel. We postulate that this gas was biogenetically produced within the organic-rich deposits.

• Electrical & Electronic Materials
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• v.9 no.9
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• pp.925-932
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• 1996

Using the d.c. 2-probe method, we have examined the temperature dependence of CO gas sensitivity of pure ZnO and ZnO CuO thick films prepared by the acqueous precipitation. At 200ppm CO gas, pure ZnO thick film shows the maximum sensitivity of -6.5 at 300.deg. C. On the other hand, the maximum sensitivity of 1-5 mol% and 10-15 mol% CuO added ZnO thick films are 2.8-2.5 and 1.6, respectively. Therefore, the sensitivity of pure ZnO thick film is about three times larger than those of ZnO-CuO thick films. We suggest that the promotion of maximum sensitivity is caused by low packing and the increase of chemical adsorptions for $O_{2}$ gas.