• KSBB Journal
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• v.31 no.4
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• pp.193-199
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• 2016

Global warming caused from the heavy consumption of fossil fuel is one of the biggest problems to be solved. Biofuel has been gained more attention as an alternative to reduce the consumption of fossil fuel. Recently, butanol produced from the genus Clostridium has been considered as one of the promising alternatives for gasoline, fossil based fuel. Nevertheless, the lack of the genome-engineering tools for the genus Clostridium is the major hurdle for the economic production of butanol. More recently, genome engineering tools have been developed for metabolic engineering of butanol-producing Clostridium species, which includes genome scale network model and genome editing tools on the basis of mobile group II introns and CRISPR/Cas system. In this study, the genome engineering tools for butanol-producing Clostridium species have been reviewed with a brief future perspective.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.3
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• pp.410-420
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• 2012

The heavy reliance on fossil fuels, especially oil and gas has triggered the global energy crisis. Continued use of petroleum fuels is now widely recognized as unsustainable because of their depleting supplies and degradation to the environment. To become less dependent on fossil fuels, current world is shifting paradigm in energy by developing alternative energy sources mainly through the utilization of renewable energy sources. In particular, bioenergy recovery from wastes with the help of microorganism is viewed as one of the promising ways to mitigate the current global warming crisis as well as to supply global energy. It has been proved that microorganism can generate power by converting organic matter into electricity using microbial fuel cells (MFCs). MFC is a bioelectrochemical device that employs microbes to generate electricity from bio-convertible substrate such as wastewaters including municipal solid waste, industrial, agriculture wastes, and sewage. Sustainability, carbon neutral and generation of renewable energy are some of the major features of MFCs. However, the MFC technology is confronted with a number of issues and challenges such as low power production, high electrode material cost and so on. This paper reviews the recent developments in MFC technology with due consideration of electrode materials used in MFCs. In addition, application of biocathodes in MFCs has been discussed.

• Transactions of the Korean hydrogen and new energy society
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• v.13 no.4
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• pp.330-338
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• 2002

A long-term energy system in the future is expected to be based on the ideal circulation system between water and hydrogen in the sense that the hydrogen prepared from water eventually returns to water again after its use. Currently, with respect to the hydrogen energy system, it is predicted that the turning-point at which the production cost of hydrogen will become to be lower than that of fossil fuels would be after 2010. However, fuel cell technology would be able to be practically used for the applications to the transportation vehicles and small-scale power sources from 2004, and therefore, an efficient construction of the infrastructure covering hydrogen production and supply systems would be required with short-/mid-term technologies for the $CO_2$ reduction associated with fossil fuel utilization. In this paper, the hydrogen quantity available in domestic market has been estimated focusing on the hydrogen by-produced from domestic industries, and also the infrastructure for hydrogen-driven vehicles like fuel cell cars has been reviewed.

• Journal of Aerospace System Engineering
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• v.8 no.4
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• pp.1-6
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• 2014

This paper presents the trade-off study of conducting a survey of the weights for various kind of propulsion systems installed in the Smart Unmanned Aerial Vehicle TR-100, a tilt-rotor vehicle, which is developed by Korea Aerospace Research Institute, in order to predict the appropriate propulsion system for present and future Personal Air Vehicle, which has single mode and vertical take-off & landing. In order to perform the trade-off study, we set the requirements that the vehicle hovers for 1 hour with 1,000 kg maximum take off weights. In this study, the power systems are classified engine, which uses the fossil fuel - turboshaft engine, piston engine, diesel engine and rotary engine, and electric motor with fuelcell or Li-Ion battery. The results of trade-off study shows the power systems using fossil fuel are superior to using fuelcell or Li-Ion battery for weight of propulsion system. Also turboshaft engine is the best power system for the aspects of system weight, and the nexts are rotary engine, piston engine, diesel engine, electric motor with Li-Ion battery, and electric motor with fuelcell.

• International journal of advanced smart convergence
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• v.4 no.1
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• pp.162-178
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• 2015

Petroleum based fossil fuels used to power most processes today are non-renewable fuels. This means that once used, they cannot be reproduced for a very long time. The maximum combustion of fossil fuels occurs in automobiles i.e. the vehicles we drive every day. Thus, there is a requirement to shift from these non-renenewable sources of energy to sources that are renewable and environment friendly. This is causing the need to shift towards more environmentally-sustainable transport fuels, preferably derived from biomass, such as biodiesel blends. These blends can be made from oils that are available in abundance or as waste e.g. waste cooking oil, animal fat, oil from seeds, oil from algae etc. Waste Cooking Oil(WCO) is a waste product and so, converting it into a transportation fuel is considered highly environmentally sustainable. Keeping this in mind, a life cycle assessment (LCA) was performed to evaluate the environmental implications of replacing diesel fuel with WCO biodiesel blends in a regular Diesel engine. This study uses Life Cycle Assessment (LCA) to determine the environmental outcomes of biodiesel from WCO in terms of global warming potential, life cycle energy efficiency (LCEE) and fossil energy ratio (FER) using the life cycle inventory and the openLCA software, version 1.3.4: 2007 - 2013 GreenDelta. This study resulted in the conclusion that the biodiesel production process from WCO in particular is more environmentally sustainable as compared to the preparation of diesel from raw oil, also taking into account the combustion products that are released into the atmosphere as exhaust emissions.

• Environmental and Resource Economics Review
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• v.23 no.3
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• pp.365-408
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• 2014

The purpose of this paper is to compare efficiencies, two stage efficiencies, and the reduction of economic growth due to the restraint of $CO_2$ and fossil fuel in two efficiency approach by pointing out the limit of traditional efficiency approach and introducing material balance approach. The efficiencies under the traditional approach and the material balance approach report significant gaps when they are analyzed in detail. Especially, in case not including fossil fuels, the low income countries show the bad performance of production efficiencies, but OECD and high-middle income countries reveal the better performance than that of the low countries. It fails to reflect the reality justly. Based on the material balance approach, the low income countries report the higher performance and the alleviated effect of environmental components for economic growth than OECD's.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.669-675
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• 2009

As the use of new and renewable energy is one of the ways by which the exhaustion of fossil fuels and the other existing environmental problems can be addressed, a policy of spreading information regarding it and of conducting R&D related to it is currently being implemented in advanced countries. In the construction field, the concept of "green building" was born, and the application of this concept has increased, with the end in view of achieving energy savings, resource savings, and recycling, and of conserving the natural environment. In this context, the government of Korea amended the "Law on the Development, Use, and Promotion of New and Recycled Energy" in 2004, which contains 11 provisions related to new and renewable energy and their sources, including solar and geothermal energy as well as sunlight, water, rainfall, and organisms. Since solar-energy should be used instead of fossil fuels by converting sunlight directly into electricity, many researches on this subject are in progress. There are few researches, however, employing the economic approach to the subject. Thus, in this study, an economic assessment of the solar-energy system was conducted using both life cycle cost (LCC) analysis and sensitivity analysis. The results of the LCC analysis show that the solar-energy system will become economically better than the fossil fuel system after 16 years, although the initial construction cost of the solar-energy system is higher than that of the fossil fuel system. The results of this study are expected to be used in selecting an eco-friendly and economical solar-energy system when the construction of a green building is planned.

• Transactions of the Korean hydrogen and new energy society
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• v.13 no.1
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• pp.3-12
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• 2002

In this study, it achieved life cycle assessment to estimate environmental performance for naphtha steam reforming that account for the production over 50% of total hydrogen output. Although hydrogen dosen't emit air emissions, especially, $CO_2$, a large of $CO_2$ is emitted in hydrogen production process. In the result of this study, it ascertained the truth that $CO_2$ is emitted at the rate of $6.3kg/kgH_2$ and that result from steam reforming reaction and use of fossil fuel in hydrogen manufacturing process. Above all, 57% of total $CO_2$ emissions is emitted in process of steam reforming of naphtha and so it knew that the principle of steam reforming is key issue in aspect to environment. Also, it compared hydrogen by fuel of fuel cell vehicle with gasoline fuel of general gasoline vehicle to analyze relative environment of hydrogen for fossil fuel during the life cycle. As the result, it might be difficult in improvement of environment because $CO_2$ emissions during the hydrogen manufacturing process is nearly the same with that during the use of gasoline.

• Environmental and Resource Economics Review
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• v.20 no.4
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• pp.761-796
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• 2011

The purpose of this paper is to derive fuel mix of electricity generating system with the lowest cost considering energy security and climate change mitigations as the target of energy policy. Energy Security Price Index(ESPI), based on the measure of market concentration in fossil fuel market and political risk of exporting countries, is chosen to assess the level of energy security. The methodology of Energy Conservation Supply Curve(CSC) is applied to fuel mix to meet the carbon emission mitigation through increasing the alternatives participation and introduction of new technologies. These also represent an improvement on the level of energy security, having the complementarity between two objectives. The alternative measure for improving energy security is exploration and production(E&P) of fossil fuel for energy sufficiency. Fuel mix of electricity generating system to achieve certain objectives in 2020 can be derived with the lowest cost considering energy security and carbon emission mitigations.

• Membrane Journal
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• v.32 no.6
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• pp.475-485
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• 2022

The continuous excessive consumption of fossil fuels is causing global warming, climate, and environmental crisis. Accordingly, hydrogen energy attracts attention among alternative energies of fossil fuels, because it has the advantage of not emitting pollutants and not having resource restrictions. Therefore, various studies are being conducted on a water electrolysis system for producing hydrogen and a fuel cell system for producing electricity by using hydrogen energy as a fuel. In this study, 3D ionomer models were produced by reflecting the excessive water condition of an anion-conductive ionomer material, which is one of the core materials of water electrolysis systems and fuel cells. Finally, by analyzing the structural stability and performance of the ionomer under an excessively hydrated condition, we suggested a performance improvement factor in the design of an anion conductive ionomer, a key material for water electrolysis systems and fuel cells.