• Biotechnology and Bioprocess Engineering:BBE
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• 제11권6호
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• pp.496-502
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• 2006

Off-flavors and unfavorable odors in tuna fish oil were successfully removed and identified using supercritical carbon dioxide extraction, while retaining variable compounds, polyunsaturated fatty acids such as EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Samples of oil were extracted in a 100 mL semi-batch stainless steel vessel under conditions which ranged from 8 to 20 MPa and $20\;to\;60^{\circ}C$ with solvent ($CO_{2}$) flows from 10 g/min. GC-MS was used to identify the main volatile components contributing to the off-flavors and odors which included 2-methyl-1-propanol, 2,4-hexadienal, cyclopropane, and octadiene. Analyses of oil extracted at $40^{\circ}C$, 20 MPa showed a 99.8% reduction in dimethyl disulfide. Other significant off-flavors identified were 2-methyl-butene, 3-hydroxy butanal and ethylbenzene.

• Journal of Advanced Marine Engineering and Technology
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• 제41권1호
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• pp.15-20
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• 2017

The International Maritime Organization(IMO) has adopted and implemented compulsory regulation for reducing greenhouse gas emission that cause global warming. However, with global warming underway, the IMO plans to enforce voluntary carbon dioxide emissions reduction based on the Ship Energy Efficient Management Plan and the Energy Efficiency Operational Indicator(EEOI) in the near future. Large container ships sail at low speeds in order to save fuel and reduce carbon dioxide emissions. However, bulbous bows designed for high-speed ships decrease fuel efficiency by acting as resistance when reduced speeds are adopted by large container ships. In order to adopt low-speed operations and increase fuel savings, the bulbous bow of a large container ship was modified into the proper shape and size. Fuel consumption was compared for checking the result of EEOI before and after modifying the bulbous bow adopted on low speed operation of large high-speed ships. The results confirmed much larger carbon dioxide emissions reduction than expected. If EEOI would be implemented as compulsory regulation for reducing carbon dioxide emissions, bulbous bow modification can be considered as one of the fuel saving methods for the high-speed ships.

• Journal of the Korean Applied Science and Technology
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• 제37권2호
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• pp.214-223
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• 2020

This study evaluated CO₂ removal efficiency, monitoring data analysis / evaluation efficiency and energy reduction efficiency in the liquor factory by L-alanine applied scrubber. The average removal rate of the scrubber was 90.45%, and it was confirmed that the removal efficiency was excellent above 10,000ppm of inlet CO₂ concentration. After the scrubber operation, the CO₂ concentration in the workplace was maintained under 2,000ppm(the carbon dioxide reduction efficiency was about 74%). and the energy saving efficiency was calculated to 7.26% by reducing the power consumption. As a result of applying the developed product, it was possible to improve the working environment of workers by reducing the carbon dioxide concentration in the workplace at low concentration without ventilation, and to reduce the energy consumption. Therefore, it is expected that the scrubber will be useful as a high CO₂ removal process in food and liquor factories.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.188-191
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• 2008

There have been many methods for producing natural gas from gas hydrate reservoirs in permafrost and sea floor sediments. It is well knownthat the depressurization should be a best option for Class 1 gas hydrate deposit, which is composed of tow layers: hydrate bearing layer and an underlying free gas. However many of gas hydrate reservoirs in sea floor sediments are classified as Class 2 that is composed of gas hydrate layer and mobile water, and Class 3 that is a single gas hydrate layer. The most appropriate production methods among the present methods such as thermal stimulation, inhibitor injection, and controlled oxidation are still under development with considering the gas hydrate reservoir characteristics. In East Sea of Korea, it is presumed that the thick fractured shale deposits could be Class 2 or 3, which is similar to the gas hydrate discovered offshore India. Therefore it is needed to evaluate the possible production methods for economic production of natural gas from gas hydrate reservoir. Here we would like to present the production of natural gas from gas hydrate deposit in East Sea with industrial flue gases from steel company, refineries, and other sources. The existing industrial complex in Gyeongbuk province is not far from gas hydrate reservoir of East Sea, thus the carbon dioxide in flue gas could be used to replace methane in gas hydrate. This approach is attractive due to the suggestion of natural gas productionby use of industrial flue gas, which contribute to the reduction of carbon dioxide emission in industrial complex. As a feasibility study, we did the NMR experiments to study the replacement reaction of carbon dioxide with methane in gas hydrate cages. The in-situ NMR measurement suggeststhat 42% of methane in hydrate cages have been replaced by carbon dioxide and nitrogen in preliminary test. Further studies are presented to evaluate the replacement ratio of methane hydrate at corresponding flue gas concentration.

• Clean Technology
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• 제17권3호
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• pp.191-200
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• 2011

Natural polymers, biopolymers, and synthetic polymers based on renewable resources are the basis for the 21th portfolio of sustainable and eco-friendly plastics but high-volume consumable plastics continue to be dominated by nondegradable petroleum-based materials. Three factors have recently made biodegradable polymers economically attractive: (i) rising costs of petroleum production resulting from the depletion of the most easily accessible reserves, (ii) environmental and economic concerns associated with waste plastics, and (iii) emissions of carbon dioxide from preparation of petroleum-based materials. These pressures have driven commercial applications based on biodegradable polymers which are related to reduction of carbon dioxide in processing, such poly(hydroxy alkanoate) and poly (lactide). Since initial degradation of these polymers leads to catastrophic mechanical failure, it is necessary to control the rate of initial degradation for commercial applications. In this article, we have a critic review on the recent progress of polymer modification for the control of degradation.

• Korean Chemical Engineering Research
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• 제56권2호
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• pp.176-185
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• 2018

As global warming accelerates, greenhouse gas reduction becomes more important. Carbon dioxide dry reforming is a promising green-house gas reduction technology that can obtain CO and $H_2$ which are high value-added materials by utilizing $CO_2$ and $CH_4$ which are greenhouse gases. However, there is a significant coking problem during operation of the dry reforming reactor. Because the carbon dioxide dry reforming is a strong endothermic reaction, the temperature of the reactor drops near the reactor inlet and causes coke formation. To solve this problem, it is important to ensure that the reaction takes place in a temperature range where coke production is minimized. In this study, we proposed a design method that can maintain reaction temperature in the region where the coke is rarely generated by using the new catalyst configuration method. The design method also optimizes the reactor by solving the optimization problem which minimizes the reactor length for a given reaction conversion by using the fuel flow rate, catalyst density, and output temperature by section as optimization variables.

• The Transactions of the Korean Institute of Electrical Engineers P
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• 제65권3호
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• pp.165-170
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• 2016

Due to environmental issues such as global warming, the reduction of greenhouse gas emissions has become an inevitable measure to be taken. Among others, the building sector accounts for 50% of total carbon dioxide emissions, which is significantly high. Therefore, in order to reduce carbon dioxide emissions of the buildings, improving the energy efficiency by utilizing wind power among renewable energy sources is recommended. In case of buildings in the planning stage, it is possible to take the load of wind power generation systems into consideration when determining installed capacity. Already completed buildings, however, should be connected to small wind electric systems according to the live loads of the buildings based on the architectural design criteria. In order to connect to a building that has already been completed, it is necessary to consider the load of the small wind electric system as well as the live load of building. In addition, we need to generate the maximum electricity possible by determining the maximum installed capacity in a small area. In this paper, we propose the method for determining maximum capacity for building integrated small wind electric systems, which takes into account the considerations associated with connecting small wind electric systems to completed buildings. This can be developed into a system linked to solar power, which makes it possible to improve the energy independence of the building. In addition, carbon dioxide reduction by improving energy efficiency is expected.

• Clinical and Experimental Pediatrics
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• 제62권9호
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• pp.344-352
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• 2019

Background: Ventilator dependency constitutes a major problem in the intensive care setting. Malnutrition is considered a major determinant of extubation failure, however, attention has been attracted to modulating carbon dioxide production through decreasing carbohydrate loading and increasing the percent of fat in enteral feeds. The detected interrelation between substrate oxidation and ventilation outcome became the base of several research to determine the appropriate composition of the nonprotein calories of diet in ventilated patients. Purpose: We aimed to assess the effect of high-fat dietary modification and nutritional status on ventilatory and final outcomes of pediatric intensive care. Methods: Fifty-one ventilated children (1 month to 12 years of age) with pulmonary disease who could be enterally fed, in the Cairo University Pediatric intensive care unit, were divided into 2 groups: group A included 25 patients who received isocaloric high-fat, low-carbohydrate diet; group B included 26 patients who received standard isocaloric diet. Comprehensive nutritional assessment was done for all patients. Results: Group A had a significant reduction in carbon dioxide tension, but no similar reduction in the duration or level of ventilatory support. Assisted minute ventilation was predicted by weight-for-age and caloric intake rather than the type of diet. Poor nutritional status was associated with higher mortality and lower extubation rates. Mild hypertriglyceridemia and some gastrointestinal intolerance were significant in group A, with no impact on the adequacy of energy or protein delivery. Conclusion: The high-fat enteral feeding protocol may contribute to reducing carbon dioxide tension, with mild hypertriglyceridemia and negligible gastrointestinal intolerance as potential adverse effects. Optimization of nutritional status rather than dietary modification may improve ventilatory and survival outcomes in critically ill-ventilated children.

• Korean Journal of Soil Science and Fertilizer
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• 제47권5호
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• pp.374-380
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• 2014

To estimate greenhouse gas (GHG) emission, the inventory of rice cultivation at the farming without agricultural chemicals was established from farmers in Gunsan, Jeonbuk province in 2011~2012. The objectives of this study were to calculate carbon footprint and analyse the major factor of GHGs. To do this, we carried out a sensitivity analysis using the analyzed main factors of GHGs and estimated the mitigation potential of GHGs. Also we suggested agricultural methods to reduce GHGs that can be appled by farmers at this region. At the farming system without agricultural chemicals, carbon footprint of rice production unit of 1 kg was 2.15 kg $CO_2.-eq.kg^{-1}$. Although the amount of carbon dioxide ($CO_2$) emission was the largest among GHGs, methane ($CH_4$) emission had the highest contribution to carbon footprint on rice production system when it was converted to carbon dioxide equivalent ($CO_2-eq.$) multiplied by the global warming potential (GWP). Main source of $CO_2$ emission in the rice farming system without agricultural chemicals was combustion of fossil fuels used by agricultural machinery. Most of the $CH_4$ was emitted during rice cultivation practice and its major emission factor was flooded paddy field in anaerobic condition. Also, most of the $N_2O$ was emitted from rice cultivation process. Major sources of the $N_2O$ emission was application of fertilizer such as compound fertilizer. As a result of sensitivity analysis in energy consumption, diesel had the highest sensitivity among the energy inputs. With the reduction of diesel consumption by 10%, it was estimated that $CO_2$ potential reduction was about 2.0%. With reducing application rate of compound fertilizer by 10%, the potential reduction was calculated that $CO_2$ and $N_2O$ could be reduced by 0.5% and 0.9%, respectively. At the condition of 10% reduction of silicate and compost, $CO_2$ and $CH_4$ could be reduced by 1.5% and 1.6%, respectively. With 8 days more drainage than the ordinary practice, $CH_4$ emission could be reduced by about 4.5%. Drainage and diesel consumption were the main sources having the largest effect on the GHG reduction at the farming system without agricultural chemicals. Based on the above results, we suggest that no-tillage and midsummer drainage could be a method to decrease GHG emissions from rice production system.

• Korean Journal of Materials Research
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• 제34권5호
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• pp.254-260
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• 2024

This study is to manufacture a titanium dioxide (TiO₂) photocatalyst by recycling sludge generated using titanium tetrachloride (TiCl₄) as a coagulant. Compared to general sewage, a TiCl₄ coagulant was applied to dyeing wastewater containing a large amount of non-degradable organic compounds to evaluate its performance. Then the generated sludge was dried and fired to prepare a photocatalyst (TFS). Scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), and nitrogen oxide reduction experiments were conducted to analyze the surface properties and evaluate the photoactive ability of the prepared TFS. After using titanium tetrachloride (TiCl₄) as a coagulant in the dyeing wastewater, the water quality characteristics were measured at 84 mg/L of chemical oxygen demand (COD), 10 mg/L of T-N, and 0.9 mg/L of T-P to satisfy the discharge water quality standards. The surface properties of the TFS were investigated and the anatase crystal structure was observed. It was confirmed that the ratio of Ti and O, the main components of TiO₂, accounted for more than 90 %. As a result of the nitric oxide (NO) reduction experiment, 1.56 uMol of NO was reduced to confirm a removal rate of 20.60 %. This is judged to be a photocatalytic performance similar to that of the existing P-25. Therefore, by applying TiCl₄ to the dyeing wastewater, it is possible to solve the problems of the existing coagulant and to reduce the amount of carbon dioxide generated, using an eco-friendly sludge treatment method. In addition, it is believed that environmental and economic advantages can be obtained by manufacturing TiO₂ at an eco-friendly and lower cost than before.