• Proceedings of the KWS Conference
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• 2007.11a
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• pp.8-10
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• 2007

In recent years, hydrogen-oxygen mixed gas generated by electrically dissociating water has been proposed as alternative cutting fuel. The mixed gas consists of a hydrogen-oxygen mixed gas in the mixture ratio of 2:1. And gas has some merits as cutting quality and speed compared with existing gas cutting process. Because main source of mixed gas is water, mixed gas is environmental-friendly clean fuel. The purpose of the present paper is to investigate cutting characteristics and optimum cutting parameters of mixed gas, The effect of cutting parameter on the cutting characteristics of mixed gas is also investigated as compared to existing gas cutting process.

• Journal of Korean Elementary Science Education
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• v.40 no.1
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• pp.36-54
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• 2021

The purpose of this study was to investigate pre-service elementary school teachers' understanding about alternative energy and to identify their alternative conceptions. The two-tier instrument had been developed by Cheong et al. (2015) were used for this study. Twelve items from the instrument consisted of four categories: 'source of alternative energy', 'greenhouse gas emission', 'cost in electricity and construction' and 'advantages and disadvantages'. One hundred and fifteen pre-service elementary school teachers were participated in online survey during the semester. The results analyzed using SPSS 26.0. were as follows: First, the correct response rate varied depending on the content of item. Items related to characteristics and advantages & disadvantages of alternative energy showed high percentage of correct answers. Whereas, items regarding the principles of alternative energy showed relatively low percentage of correct answers. Second, there are some items showing statistically meaningful differences according to students' high school track. Nevertheless, there are no significant differences in overall. Third, we identified twelve alternative conceptions about alternative energy from students' answer distribution. Educational implications were discussed based on the results.

• Journal of Environmental Science International
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• v.23 no.9
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• pp.1643-1654
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• 2014

The university is one of the main energy consumption facilities and thereby releases a large amount of greenhouse gas (GHG). Accordingly, efforts for reducing energy consumption and GHG have been established in many local as well as international universities. However, it has been limited to energy consumption and GHG, and has not included air pollution (AP). Therefore, we estimated GHG and AP integrated emissions from the energy consumed by Seoul National University of Science and Technology during the years between 2010 and 2012. In addition, the effect of alternative energy use scenario was analysed. We estimated GHG using IPCC guideline and Guidelines for Local Government Greenhouse Inventories, and AP using APEMEP/EEA Emission Inventory Guidebook 2013 and Air Pollutants Calculation Manual. The estimated annual average GHG emission was $11,420tonCO_{2eq}$, of which 27% was direct emissions from fuel combustion sectors, including stationary and mobile source, and the remaining 73% was indirect emissions from purchased electricity and purchased water supply. The estimated annual average AP emission was 7,757 kgAP, of which the total amount was from direct emissions only. The annual GHG emissions from city gas and purchased electricity usage per unit area ($m^2$) of the university buildings were estimated as $15.4kgCO_{2eq}/m^2$ and $42.4tonCO_{2eq}/m^2$ and those per person enrolled in the university were $210kgCO_{2eq}$/capita and $577kgCO_{2eq}$/capita. Alternative energy use scenarios revealed that the use of all alternative energy sources including solar energy, electric car and rain water reuse applicable to the university could reduce as much as 9.4% of the annual GHG and 34% of AP integrated emissions, saving approximately 400 million won per year, corresponding to 14% of the university energy budget.

• Journal of Welding and Joining
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• v.33 no.4
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• pp.17-23
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• 2015

Laser-gas metal arc hybrid welding has been considered as an alternative process of gas metal arc welding for offshore pipe laying. Fiber delivered high power lasers which enable deep penetration welding were recently developed but high power welding characteristics were not fully understood yet. In this study, the influence of shielding gas composition on welding phenomena in high power laser welding was investigated. Bead shapes, melt ejection and dropping were observed after autogenous laser welding with 100% Ar, Ar-20% $CO_2$, Ar-50% $CO_2$, and 100% $CO_2$ shielding gas. Process parameter window was widest with Ar-50% $CO_2$ shielding gas and the penetration was deepest with 100% $CO_2$ shielding gas. The melt dropping was not observed when Ar-50% $CO_2$ or 100% $CO_2$ shielding gas was supplied.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.123-131
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• 1999

Natural gas is one of the most promising alternative fuels for automotive vehicles. However, natural gas varies in compositional between the originating fields and may be further modified due to processing and additional mixing. These variations are known to affect engine performance and emissions through changes in fuel metering and combustion characteristics. In the present study, the effect of gas compositions on vehicle performance such as fuel economy, driveability and exhaust emissions was examined. Analysis are made of using 3 types of NGVs which were made by automakers and 6 different fuels which are selected in consideration of the variation in fuel composition on the worldwide market. The results may be utilized to develop natural gas natural gas engine in automaekrs and/or to establish the fuel standard in the refueling stations.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.5
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• pp.669-675
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• 2012

Recently, the amount of electrical heat pump(EHP), a electrical conditioning equipment, is sharply increasing due to the luxury and multi-story trend of building. Accordingly, the cooling load that occupying substantial part of summer electric consumption has increased dramatically, making difficulties in domestic supply of electricity in summer. There are some efforts to replace it with an alternative cooling equipment such as gas heat pump(GHP), a gas cooling equipment, in order to solve the problem of summer electricity supply through reducing the summer electricity peak. It is rare, however, to find studies on the actual effects of GHP on the reduction of summer electricity peak. This study, therefore, estimated the effects of the GHP on the summer electricity peak by the gas consumption and characteristics of gas cooling systems. In addition, electric substitution effects by gas cooling systems were analyzed through case studies in the summer of 2010.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.3
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• pp.58-63
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• 2009

The global restriction on pollutant emissions and the soaring of crude oil price are expected to result in the change of future transportation system. Hydrogen is considered to be the leading candidate as an alternative energy source before other new alternative energy sources emerge. Scientists anticipate that hydrogen fuel gas turbine engine and fuel cell will be the power plant of the aircraft in the near future. To realize the aircraft powered by fuel cell system in the future, the technologies such as fuel cell with higher energy density, compressed gas or liquid storage system of hydrogen fuel, and efficient and lightweight electric motor have to be developed first.

• International Journal of Highway Engineering
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• v.16 no.3
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• pp.75-84
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• 2014

PURPOSES : Traffic congestions which occur in the intersections of arterials lead to mobility and environment problem, and then traffic agencies and engineers have been struggling for mitigating congestions with greenhouse gas emissions. As an alternative of solving theses problems, this study is to introduce a low-cost and high-effectiveness countermeasure as unconventional intersections which are successfully in operation in U.S.. The main feature of unconventional intersections is to reroute turning movement on an approach to other approach, which consequently more green time is available for the progression of through traffic. Due to improved progression, this unique geometric design contributes to reduce delays with greenhouse gas emission and provides a viable alternative to interchanges. This study is to evaluate the potential operation and environment benefits of unconventional intersections. METHODS : This study used the VISSIM model with Synchro and EnViVer. Synchro is to optimize signal phases and EnViVer model to estimate the amount of greenhouse gas emissions by each condition. RESULTS : The result shows that unconventional intersections lead to increase the capacity and to reduce greenhouse gas emissions, compared to existing intersections. CONCLUSIONS : Unconventional intersections have the ability to positively impact operations and environments as a low-cost and high-effectiveness countermeasure.

• Journal of the Korean Solar Energy Society
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• v.32 no.1
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• pp.32-39
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• 2012

New and renewable energy systems(solar thermal system, photovoltaic system, geothermal system, wind power system) are environmentally friendly technologies and these in South Korea are very important measures to reduce greenhouse-gas(GHG) and to push ahead with Green Growth. The purpose of this paper is to analyze GHG mitigation potential by distribution of solar thermal system in housing sector with bottom-up model called 'Long-range Energy Alternative Planning system'. Business as usual(BAU) was based on energy consumption characteristic with the trend of social-economic prospects and the volume of housing. The total amount of GHG emission of BAU was expected to continuous increase from 66.0 million-ton $CO_{2e}$ in 2007 to 73.1 million-ton $CO_{2e}$ in 2030 because of the increase of energy consumption in housing. The alternative scenario, distribution of solar thermal system in housing sector had GHG mitigation potential 1.54 million-ton $CO_{2e}$ in 2030. The results of this study showed that new and renewable energy systems made a contribution of reducing the use of fossil fuel and the emission of greenhouse-gas in building.

• Journal of the Korean Institute of Gas
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• v.17 no.4
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• pp.26-32
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• 2013

The best way to prevent major occupational accidents is prohibiting use of hazardous substances such as flammable gas, toxic gas whereas using alternative substances that ensured safety. but if there are no economic efficiency and substituting technologies of alternative substances, the best way is preparing to prevent accidents thoroughly. Therefore, this study has developed and selected release scenarios to use and apply for consequence analysis and emergency action plan for HF charging process of chemical plants that have HF release accidents and high probability of release accidents.