• Applied Chemistry for Engineering
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• v.20 no.1
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• pp.1-8
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• 2009

Bio-oil has attracted considerable interest as one of the promising renewable energy resources because it can be used as a feedstock in conventional petroleum refineries for the production of high value chemicals or next-generation hydrocarbon fuels. Currently, catalytic vapor cracking is considered the most potential upgrading method for stabilization of bio-oil, which is a pre-process required prior to feeding bio-oil into refineries. This review introduces the recent research and development trends on bio-oil upgrading via catalytic vapor cracking, focusing on catalysts and upgrading methods used.

• Membrane Journal
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• v.22 no.3
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• pp.155-170
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• 2012

Fuel cells have been considered as alternative power generation system in the twenty-first century because of eco-friendly system, high power density and efficiency compare with petroleum engine system. Proton exchange membranes (PEMs) are the key components in fuel cell system. Currently, Nafion has been used in fuel cell system. However, Nafion has disadvantages such as low conductivity at high temperature and high cost. The researchers have focused to reach the high properties such as high proton conductivity, low permeability to fuel, good chemical/thermal stability, good mechanical properties and low manufacturing cost. Various methods have been developed for preparation of proton exchange membrane with high performance and commercialization of fuel cell system. The hybrid organic/inorganic membrane has the potentials to provide a unique combination of organic and inorganic properties with improved proton conductivity and mechanical property at high temperatures. So, this paper presents an overview of research trend for the composite membranes prepared by organic/inorganic system using various inorganic materials.

• Journal of Microbiology and Biotechnology
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• v.29 no.5
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• pp.776-784
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• 2019

Polyhydroxybutyrate (PHB), the most well-known polyhydroxyalkanoate, is a bio-based, biodegradable polymer that has the potential to replace petroleum-based plastics. Lignocellulose hydrolysate, a non-edible resource, is a promising substrate for the sustainable, fermentative production of PHB. However, its application is limited by the generation of inhibitors during the pretreatment processes. In this study, we investigated the feasibility of PHB production in E. coli in the presence of inhibitors found in lignocellulose hydrolysates. Our results show that the introduction of PHB synthetic genes (bktB, phaB, and phaC from Ralstonia eutropha H16) improved cell growth in the presence of the inhibitors such as furfural, 4-hydroxybenzaldehyde, and vanillin, suggesting that PHB synthetic genes confer resistance to these inhibitors. In addition, increased PHB production was observed in the presence of furfural as opposed to the absence of furfural, suggesting that this compound could be used to stimulate PHB production. Our findings indicate that PHB production using lignocellulose hydrolysates in recombinant E. coli could be an innovative strategy for cost-effective PHB production, and PHB could be a good target product from lignocellulose hydrolysates, especially glucose.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.52-58
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• 2023

With the increasing awareness of the importance of carbon neutrality in response to global climate change, the utilization of hydrogen as a carbon-free fuel source is also growing. Hydrogen is commonly used in fuel cells (FC), but it can also be utilized in internal combustion engines (ICE) that are based on combustion. Particularly, ICEs that already have established infrastructure for production and supply can greatly contribute to the expansion of hydrogen energy utilization when it becomes difficult to rely solely on fuel cells or expand their infrastructure. However, a disadvantage of utilizing hydrogen through combustion is the potential generation of nitrogen oxides (NOx), which are harmful emissions formed when nitrogen in the air reacts with oxygen at high temperatures. In particular, for the EURO-7 exhaust regulation, which includes cold start operation, efforts to reduce exhaust emissions during the warm-up process are required. Therefore, in this study, the characteristics of nitrogen oxides and fuel consumption were investigated during the warm-up process of cooling water from room temperature to 88℃ using a 2-liter direct injection spark ignition (SI) engine fueled with hydrogen. One advantage of hydrogen, compared to conventional fuels like gasoline, natural gas, and liquefied petroleum gas (LPG), is its wide flammable range, which allows for sparser control of the excessive air ratio. In this study, the excessive air ratio was varied as 1.6/1.8/2.0 during the warm-up process, and the results were analyzed. The experimental results show that as the excessive air ratio becomes sparser during warm-up, the emission of nitrogen oxides per unit time decreases, and the thermal efficiency relatively increases. However, as the time required to reach the final temperature becomes longer, the cumulative emissions and fuel consumption may worsen.

• Journal of the Korean earth science society
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• v.27 no.1
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• pp.20-31
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• 2006

This study analysed student teachers' notable questions about the earth science contents in the elementary science textbooks. The contents of notable questions were defined as ‘notable question contents 1' and 'notable question contents 2'. Both the question contorts are contents about which the number of questions is above three times and from two times to three times as much as the mean number of questions per page of each unit respectively. The results are as follows. First, question contents 1 are found as 'clouds observation', 'geological strata formation' and so on. Question contents 2, 'rainfall measurement', 'moon's movement during one night' and so on are found. Second, the number of interrelationships of main terms in questions increased in each question of question contents 1, but 4 term-patterns are found more in question contents 2 than question contents 1. Third, high interrelationship patterns of terms in question contents 1 are 'coal and petroleum-generation', 'metamorphosis-heat and pressure', 'metamorphosis-heat and pressure-metamorphic rocks', 'planet-sun-comet-revolution' and in question contents 2. 'constellation plate-use', 'dryness and wetness hygrometer-principle', 'seismograph-principle-earthquake', 'earth rotation axis-tilting-occurrence', 'dryness and wetness hygrometer-principle-humidity' and so on. The sources of questions analysed in this study are estimated as the content construction system of textbooks, or students' general questions about the earth science contents. If this is the former, the problems in texts and illustrations in textbooks should be articulated and resolved. And if the latter, the elementary science curriculum has to be reconsidered in view of scientific literacy in earth science.

• Journal of Energy Engineering
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• v.14 no.2 s.42
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• pp.159-166
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• 2005

In Korea, although the generation of waste plastic has been increasing, the rate of recycling is considerably low and moreover, there is no suitable method for the treatment of waste plastics. However, pyrolysis, which is appropriate for the treatment of highly polymerized compounds, such as plastics, has recently gained much interest. In this study, a property of the products from the pyrolysis of mixed waste plastics, with a possible practical use for the recycling oil produced, were assessed. First of all, in order to investigate the pyrolysis characteristic of waste plastics, TGA (Thermogravimetric analysis) and DCS (Differential Scanning Calorimetry) were performed on a number of different plastics, including PP, LDPE, HDPE, PET and PS, as well as others. According to the result, it appeared that PP was the most efficiently pyrolyzed by changing the temperature, followed by LDPE, HDPE, PET, PS and the other plastics, in that order. From the results, the optimum conditions f3r pyrolysis were set up, and the different waste plastics pyrolyzed. The recycling oil produced from the flammable gases generated during the pyrolysis was com-pared with fuel oil by an analysis using the petroleum quality inspection method on KS(Korea industrial Standard). The results of the analysis showed the recycling oil was of a similar standard to fuel oil, with the exception of the ignition point, with a quality somewhere between that of paraffin oil and diesel fuel. With respect to these results, the quality of the recycling oil produced by the pyrolysis of waste plastics was suf-ficient for use as fuel oil.

• Journal of Digital Convergence
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• v.17 no.7
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• pp.131-138
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• 2019

The world's electricity production ratio is 40% for coal, 20% for natural gas, 16% for hydroelectric power, 15% for nuclear power and 6% for petroleum. Fossil fuels also cause serious problems in terms of price and supply because of the high concentration of resources on the earth. Solar energy is attracting attention as a next-generation eco-friendly energy that will replace fossil fuels with these problems. In this study, we test the charge-operation plan and the discharge operation plan for peak-cut operation by applying the maximum power demand reduction simulation. To do this, we selected the electricity usage from November to February, which has the largest amount of power usage, and applied charge / discharge logic. Simulation results show that the contract power decreases as the peak demand power after the ESS Peak-cut service is reduced to 50% of the peak-target power. As a result, the contract power reduction can reduce the basic power value of the customer and not only the economic superiority can be expected, but also contribute to the improvement of the electric quality and stabilization of the power supply system.

• Journal of the Korean Geotechnical Society
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• v.25 no.6
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• pp.17-29
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• 2009

There has been an increase in the investigation of deep sea sediments with a consequent increase in the amount of energy required to undertake these investigations. The geotechnical characteristics of Ulleung Basin sediment are explored by using depressurized specimens following methane production tests carried out on pressured core samples obtained at 2,100 m water depth and 110 m below sea floor. Geotechnical index tests, X-ray diffraction, and scanning electron microscope are conducted to identify the geotechnical index parameters, clay mineralogy, chemical composition, and microstructure of the sediments. Compressibility, and elastic and electromagnetic wave parameters are investigated for two samples by using a multi sensing instrumented oedometer cell. The strength chatracteristics are obtained by the direct shear tests. The dominant clay minerals are mostly kaolinite, illite, chlorite, and calcite. The SEM shows a well-developed flocculated structure of the microfossil. Void ratio, electrical resistivity, real permittivity, conductivity, and shear wave velocity show bi-linear behavior with the effective vertical stress: as the vertical effective stress increases. The friction angle obtained by the direct shear test is about $21^{\circ}$, which is similar to the value observed in the Ulleung Basin sediments. This study shows that the understanding of the behavior acting on the diatomaceous marine sediment is important because it often maintains the useful energy resources such as gas hydrate and so will be the new engineering field in the next generation.

• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.1-11
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• 2017

Bio-oil has attracted considerable interest as one of the promising renewable energy resources because it can be used as a feedstock in conventional petroleum refineries for the production of high value chemicals or next-generation hydrocarbon fuels. Zeolites have been shown to effectively promote cracking reactions during pyrolysis resulting in highly deoxygenated and hydrocarbon-rich compounds and stable pyrolysis oil products. In this study, catalytic pyrolysis was applied to upgrade bio-oil from yellow poplar and then fuel characteristics of upgraded bio-oil was investigated. Yellow Poplar(500 g) which ground 0.3~1.4 mm was processed into bio-oil by catalytic pyrolysis for 1.64 seconds at $465^{\circ}C$ with Control, Blaccoal, Whitecoal, ZeoliteY and ZSM-5. Under the catalyst conditions, bio-oil productions decreased from 54.0%(Control) to 51.4 ~ 53.5%, except 56.2%(Blackcoal). HHV(High heating value) of upgraded bio-oil was more lower than crude bio-oil while the water content increased from 37.4% to 37.4 ~ 45.2%. But the other properties were improved significantly. Under the upgrading conditions, ash and TAN(Total Acid Number) is decrease and particularly important as transportation fuel, the viscosity of bio-oil decreased from 6,933 cP(Control) to 2,578 ~ 4,627 cP. In addition, ZeoliteY was most effective on producing aromatic hydrocarbons and decreasing of from the catalytic pyrolysis.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.12
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• pp.874-885
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• 2011

In this study, the urban $CO_2$ emission based on energy consumption (Coal, Petroleum, Electricity, and City Gas) in 16 provincial and metropolitan city governments in South Korea was evaluated. For calculation of the urban $CO_2$ emission, direct and indirect emissions were considered. Direct emissions refer to generation of greenhouse gas (GHG) on-site from the energy consumption. Indirect emissions refer to the use of resources or goods that discharge GHG emissions during energy production. The total GHG emission was 497,083 thousand ton $CO_2eq.$ in 2007. In the indirect GHG emission, about 240,388 thousand ton $CO_2eq.$ was occurred, as 48% of total GHG emission. About 256,694 thousand ton $CO_2eq.$ (52% of total GHG emissions) was produced in the direct GHG emission. This amount shows 13% difference with 439,698 thousand ton $CO_2eq.$ which is total national GHG emission data using current calculation method. Local metropolitan governments have to try to get accuracy and reliability for quantifying their GHG emission. Therefore, it is necessary to develop and use Korean emission factors than using the IPCC (Intergovernmental Panel on Climate Change) emission factors. The method considering indirect and direct GHG emission, which is suggested in this study, should be considered and compared with previous studies.