• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.3
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• pp.138-147
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• 2007

An emergy concept was used to evaluate the environment and economy of the Han River basin in Korea and to suggest policy perspectives far the sustainable utilization of its environment and associated estuarine ecosystem. The economy of the basin used $5.19{\times}10^{23}\;sej/yr$ of emergy in 2005. The economy of the Han River basin was heavily dependent on outside energy sources from foreign countries and other parts of Korea, with internal sources, renewable and nonrenewable, contributing only 15.6% to the total emergy use. The basin's trade balance in terms of emergy showed trade surplus, whereas there was a deficit in monetary terms. The population of the Han River basin was far greater than the carrying capacity calculated using the emergy flow, with renewable carrying capacity only at 1.8% of the basin's population and developed carrying capacity at 14.3%. The economy of the basin imposed a substantial stress on its environment, with an environmental loading ratio of 54.8. Overall, the economy of the Han River basin was not sustainable with an emergy sustainability of 0.02. These are reflected in lower quality of living expressed in the emergy term than the national average. Deconcentration of population and economic activities is needed to reduce environmental stress on the environment of the basin and its valuable estuarine ecosystem. Policies to restore ecosystem productivity of the basin are also needed to ensure the sustainability of the basin's economic activities and the sustainable utilization of the Han River estuary. In this regard, it is urgently needed for the Korean government to implement sustainable management measures for the Han River estuary, a well-preserved, productive natural estuarine ecosystem in Korea.

• Journal of Energy Engineering
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• v.23 no.2
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• pp.125-148
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• 2014

This paper performs a historical analysis on the various factors contributing to the current carbon lock-in of Korean electricity industry by using techo-institutional complex. The possibilities of the industry's carbon lock-out toward more sustainable development are also investigated. It turns out that market, firm, consumer, and government factors are all responsible for the development of the carbon lock-in of Korean power industry; the Korean government consistently favoring large power plants based on the economy of scale; below-cost electricity tariff; inflation policy to suppress increases in power price; rapid demand growth in summer and winter seasons; rigidities of electricity tariff; and expansion of gas-fired and imported coal-fired large power plants. On the other hand, except for nuclear power generation and smart grid, environment laws and new and renewable energy laws are the other remaining factors contributing to the carbon lock-out. Considering three key points that Korea is an export-oriented economy, the generation mix is the most critical factor to decide the amounts of carbon emission in the power industry, and the share of industry and commercial power consumption is over 85%, it is unlikely that Korea will achieve the carbon lock-out of power industry in the near future. Therefore, there are needs for more integrated approaches from market, firm, consumer, and government all together in order to achieve the carbon lock-out in the electricity industry. Firstly, from the market perspective, it is necessary to persue more active new and renewable energy penetration and to guarantee consumer choices by mitigating the incumbent's monopoly power as in the OECD countries. Secondly, from the firm perspective, the promotion of distributed energy system is urgent, which includes new and renewable resources and demand resources. Thirdly, from the consumer perspective, more green choices in the power tariff and customer awareness on the carbon lock-out are needed. Lastly, the government shall urgently improve power planning frameworks to include the various externalities that were not properly reflected in the past such as environmental and social conflict costs.

• Journal of Appropriate Technology
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• v.7 no.2
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• pp.127-135
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• 2021

To respond to the threat of global warming, countries around the world are promoting the spread of renewable energy and reduction of carbon emissions. In accordance with the United Nation's Sustainable Development Goal to combat climate change and its impacts, global automakers are pushing for a full transition to electric vehicles within the next 10 years. Electric vehicles can be a useful means for reducing carbon emissions, but in order to reduce carbon generated in the stage of producing electricity for charging, a power generation system using eco-friendly renewable energy is required. In this study, we propose a smart electric mobility operating system integrated with off-grid solar power plants established in Tanzania, Africa. By applying smart monitoring and communication functions based on Arduino-based computing devices, information such as remaining battery capacity, battery status, location, speed, altitude, and road conditions of an electric vehicle or electric motorcycle is monitored. In addition, we present a scenario that communicates with the surrounding independent solar power plant infrastructure to predict the drivable distance and optimize the charging schedule and route to the destination. The feasibility of the proposed system was verified through test runs of electric motorcycles. In considering local environmental characteristics in Tanzania for the operation of the electric mobility system, factors such as eco-friendliness, economic feasibility, ease of operation, and compatibility should be weighed. The smart electric mobility operating system proposed in this study can be an important basis for implementing the SDGs' climate change response.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.672-682
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• 2020

The Korea Nowadays, which is research on digital twin technology for efficient operation in various industrial/manufacturing sites, is being actively conducted, and gradual depletion of fossil fuels and environmental pollution issues require new renewable/eco-friendly power generation methods, such as wave power plants. In wave power generation, however, which generates electricity from the energy of waves, it is very important to understand and predict the amount of power generation and operational efficiency factors, such as breakdown, because these are closely related by wave energy with high variability. Therefore, it is necessary to derive a meaningful correlation between highly volatile data, such as wave height data and sensor data in an oscillating water column (OWC) chamber. Secondly, the methodological study, which can predict the desired information, should be conducted by learning the prediction situation with the extracted data based on the derived correlation. This study designed a workflow-based training model using a machine learning framework to predict the pressure of the OWC. In addition, the validity of the pressure prediction analysis was verified through a verification and evaluation dataset using an IoT sensor data to enable smart operation and maintenance with the digital twin of the wave generation system.

• Journal of Plant Biotechnology
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• v.37 no.3
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• pp.319-326
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• 2010

An interest in the production of seed-oil based fuel and raw materials, which comes from renewable plant sources, has been intrigued by the phenomenon of global warming and shortage of fossil fuels. Rapeseed (Brassica napus) is the most important oilseed crop, which produces seeds with 40% oil. It is desirable to develop genetically modified rapeseed producing oils, which can be easily converted to biodiesel. As an initial step for development of genetically modified rapeseed for the production of biofuels or bio-based materials, Korean rapeseed cultivars, Naehan, Youngsan, Tammi and Halla, were analyzed. Four Korean rapeseed cultivars produce 32 to 40% oil of seed dry weight, which is rich in oleic acid (more than 60 mole%). The cotyledonary petioles of rapeseed cultivar, Halla, were transformed using Agrobacterium tumefaciens strain GV3101, carrying the uidA gene encoding $\beta$-glucuronidase (GUS) as a reporter gene and the phosphinothricin acetyltransferase (PAT) gene as a selectable marker. The stable integration of PAT gene in the genome of transgenic rapeseeds was confirmed by PCR analysis. Expression of uidA gene in various rapeseed organs was determined by fluorometric assay and histochemical staining. Transformation efficiency of a Korean rapeseed Halla cultivar was 10.4%. Genetic inheritance of transgenes was confirmed in $T_2$ generation.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.4
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• pp.231-236
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• 2014

Sawdust, produced as an wood by-product, is usable biomass as liquid fuels if decomposed to monomer unit, because the chemical structure are similar to high octane materials found in gasoline. In this study, parameters of thermochemical degradation by acetone-solvolysis reaction of sawdust such as the effect of reaction temperature, reaction time and type of solvent on conversion yield and degradation products were investigated. The liquid products by acetone-solvolysis from sawdust produced various kind of ketone, phenol and furan compounds. The optimum sawdust conversion was observed to be 88.7% at $350^{\circ}C$, 40min. Combustion heating value of liquid products from thermochemical conversion processes was as high as 7,824 cal/g. The energy yield and mass yield in acetone-solvolysis of sawdust was 60.8% and 36.4 g-oil/100g-sawdust after 40 min of reaction at $350^{\circ}C$, respectively. The major components of the acetone-solvolysis products, that could be used as liquid fuel, were 4-methyl-3-pentene-2-one, 1,3,5-trimethylbezene, 2,6-dimethyl-2,5-heptadiene-4-one, 3-methyl-2-cyclopenten-1-one as ketone compounds.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.105-108
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• 2011

The increased concern for the security of the oil supply and the negative impact of fossil fuels on the environment, particularly greenhouse gas emissions, has put pressure on society to find renewable fuel alternatives. Compared to the traditional biofuel, ethanol, higher alcohols offer advantage as gasoline substitutes because of their higher energy density and lower hygroscopicity. For this reason, microbial fermentation is known as potential producers for sustainable energy carriers. In this study, bacterial responses including cellular and molecular toxicity were studied in three different microorganisms, such as Escherichia coli, Clostridium acetobutylicum, and Saccharomyces cerevisiae. In this study, it was analyzed specific stress responses caused by ethanol and buthanol using four different stress responsive genes, i.e. fabA, grpE, katG and recA. The expression levels of these genes were quantified by semi-quantitative reverse transcription-PCR. It was found that four genes have shown different responsive patterns when E. coli cultures were under stressful conditions caused by ethanol and buthanol, respectively. Therefore, in this study, the stress responsive effects caused by these alcohols and the extent of each stress response can be analyzed using the expression levels and patterns of different stress responsive genes.

• Journal of the Korean Society for Railway
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• v.17 no.2
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• pp.94-99
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• 2014

Recently, trends in new transportation system development have been primarily focused on sustainable and ecofriendly mobility solutions. The personal rapid transit (PRT) system has been considered a promising candidate in this category; its competitiveness is being improved through convergence with cutting-edge electric vehicle (EV) technologies. However, battery-powered vehicles pose difficult technical challenges in attempts to achieve reliable and efficient operation. In this study, a design approach for a solar-power assisted PRT system is presented with small-scale demonstrations aimed at circumventing challenges facing its adoption, as well as helping speed the transition to electric-powered ground transportation. From the results, it is expected that flexible photovoltaic (PV) cells will be able to supply 11% of the power required by the service equipment installed in a prototype vehicle. In particular, flexible photovoltaic (PV) cells are advantageous in terms of cost, weight, and design considerations. Most importantly, the cells' flexibility and attach-ability are expected to give them great potential for extended application in various areas.

• Korean Journal of Environmental Biology
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• v.32 no.1
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• pp.26-34
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• 2014

Due to the rapid energy consumption and fossil fuel abundance reduction, the world is progressively in need of alternative and renewable energy sources such as biodiesel. Biodiesel from microalgae offers high hopes to the scientific world for its potential as well as its non-competition with arable lands. Taking consideration to reduce the cost of production as well as to attain twin environmental goals of treatment and use of animal waste material the microalgal cultivation using piggery manure has been tested in this study. Unialgal strains such as Chlorella sp. JK2, Scenedesmus sp. JK10, and an indigenous mixed microalgal culture CSS were cultured for 20 days in diluted piggery manure using Small Scale Raceway Pond (SSRP). Biomass production and lipid productivity of CSS were $1.19{\pm}0.09gL^{-1}$, $12.44{\pm}0.38mgL^{-1}day^{-1}$, respectively and almost twice that of unialgal strains. Also, total nitrogen and total phosphorus removal efficiencies of CSS was 93.6% and 98.5% respectively and 30% higher removal efficiency compared to the use of unialgal strains. These results indicate that the piggery manure can provide microalgae necessary nitrogen and phosphorus for growth thereby effectively treating the manure. In addition, overall cost of microalgal cultivation and subsequently biodiesel production would be significantly reduced.

• Journal of Adhesion and Interface
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• v.22 no.1
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• pp.1-7
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• 2021

The importance of high capacity energy storage devices has recently emerged for stable power supply through renewable energy generation. From this point of view, the Na-air battery (NAB), which is a next-generation secondary battery, is receiving huge attention because it can realize a high capacity through abundant and inexpensive raw materials. In this study, activated carbon-based catalysts for hybrid type Na-air batteries were prepared and their characteristics were compared and analysed. In particular, from the viewpoint of resource recycling, activated carbon (Orange-C) was prepared using discarded orange peel, and performance was compared with Vulcan carbon, which is widely used. In addition, a Pt/C catalyst (homemade-Pt/C, HM-Pt/C) was synthesized using a modified polyol method to check whether the prepared activated carbon can be used as a supported catalyst, and a commercial Pt/C catalyst (Commercial Pt/C) and electrochemical performance were compared. The prepared Orange-C exhibited a typical H3 type BET isotherm, which is evidence that micropore and mesopore exist. In addition, in the case of HM-Pt/C, it was confirmed through TEM analysis that Pt particles were evenly distributed on the activated carbon supported catalyst. In particular, the HM-Pt/C-based NAB showed the smallest voltage gap (0.224V) and good voltage efficiency (92.34%) in the 1st galvanostatic charge-discharge test. In addition, the cycle performance test conducted for 20 cycles showed the most stable performance.