• 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.

• Food Science and Biotechnology
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• 제18권1호
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• pp.66-72
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• 2009

An aqueous ribose-cysteine model system (initial pH 5.6) was conventionally heated to the same browning at varying temperatures ($120-180^{\circ}C$), supercritical carbon dioxide (SC-$CO_2$, 20 MPa) was also applied on the same matrices for same periods at each temperature and about 20% reduction of the absorbance at 420 nm was observed as compared with sole thermal treatment. The headspace volatiles from Maillard reaction mixtures were analyzed by solid-phase microextraction (SPME) in combination with gas chromatography and mass spectrometry (GC-MS), and predominated with sulfur containing compounds, such as thienothiophenes, polysulfur alicyclics, thiols, and disulfides. Reaction temperature exhibited complex effects on volatiles formation and those effects became further complicated by the SC-$CO_2$ treatment. The formation of noncarbonyl polysulfur heterocyclic compounds and thienothiophenes was generally favored at high temperatures. Most volatiles were inhibited in SC-$CO_2$ as compared with thermal treatment alone, however, the well-known meaty aromatic compounds, such as thiols and disulfides, were obviously enhanced.

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

국제해사기구(IMO)는 온난화의 원인인 온실가스 감축을 위한 강제 규제를 도입하여 시행을 하고 있다. 하지만 여전히 지구의 온난화는 진행 중에 있고, IMO는 빠른 시일 내에 SEEMP와 EEOI에 기반한 자발적인 이산화탄소 감축 방법을 강제화 하려는 움직임이 있다. 연료 및 이산화탄소 절감을 위해 대형 컨테이너 선박은 낮은 속도에서 운항을 결정하였다. 하지만 높은 선속으로 설계되어진 선수 구조는 오히려 선속 저하 때는 저항으로 작용하여 연료 절감 효과를 저해하는 현상을 발견하였다. 대형 컨테이너 선박의 저속화를 위해 선수 구상부를 개조하여 더욱더 높은 연료 절감을 시행하였다. 고속 대형선의 저속 운항에 적합한 선수 개조가 얼마나 효율적으로 운항선 에너지효율지수를 변하게 하는지를 개조 전후의 연료 소비량을 비교 검토하였다. 그 결과 예상했던 것보다 많은 이산화탄소 감축량을 확인하였다. 운항선 이산화탄소 감축 강제 규제가 시행된다면 고속선들의 연료 절감 방법의 하나로 효과적인 적용 방법으로 고려되어진다. 또한 연료절감형 운항 선박에 투자하여 에너지 효율적인 선박으로 운항하기 위한 것이다.

• 한국응용과학기술학회지
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• 제37권2호
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• pp.214-223
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• 2020

본 연구는 L-alanine을 적용한 스크러버의 주류공장 내 CO₂ 제거효율, 모니터링 데이터 분석/평가 및 에너지 저감효율을 평가하였다. 스크러버의 평균 제거율은 90.45%로 10,000 ppm이상의 고농도 CO₂가 유입됨에도 제거효율이 뛰어난 것을 확인하였다. 스크러버 작동 후 작업장 내 CO₂는 2,000ppm 이하로 유지하여 약 74% 이상의 이산화탄소 저감 효율을 확인하였다. 또한 소비되는 전력량을 측정한 결과 스크러버 작동 후 230 kWh로 약 7.26%의 에너지가 절감되는 것으로 나타났다. 즉, 본 개발제품을 적용한 결과로 작업장 내 이산화탄소 농도를 외기유입 없이 낮은 농도로 유지함에 따라 근무자의 작업환경을 개선시킬 수 있었으며 에너지 소비량 또한 저감할 수 있었다. 그러므로 식품, 주류공장 내 고농도 CO₂ 제거 공정으로써 스크러버가 유용할 것으로 기대된다.

• 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.

• 청정기술
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• 제17권3호
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• pp.191-200
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• 2011

재생 가능한 자원으로 만들어지는 천연고분자, 바이오 고분자 및 합성고분자들은 지속가능하며 환경 친화적인 플라스틱으로 21세기 화두가 되고 있으나 많은 양의 썩지 않는 석유화학 유래 플라스틱이 사용되고 있다. 최근 들어 세 가지 관점에서 생분해성 고분자들이 많은 관심을 받고 있다: 1. 채취하기 쉬운 자원의 고갈에 따른 석유제품의 가격상승, 2. 폐플라스틱에 대한 환경 및 경제적인 관심, 3. 석유화학 유래 재료의 제조에 따른 이산화탄소배출. 이러한 관점에서 제조공정상에서 이산화탄소를 저감할 수 있는 poly(hydroxy alkanoate)나 poly(lactide)와 같은 생분해성 고분자에 대한 상업적 응용에 대한 관심이 고조되고 있다. 이들 고분자들은 초기분해가 진행됨에 따라 급격히 기계적 물성을 상실하기 때문에 상업적 응용을 위하여서는 분해거동이 중요하다. 본 총설에서는 초기분해속도의 조절을 위한 고분자 개질에 대한 최근의 연구동향을 살펴보았다.

• 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.

• 전기학회논문지P
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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.

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

지구 온난화가 가속화됨에 따라 온실가스 감축이 보다 중요해졌다. 이산화탄소 건식 개질은 온실가스인 $CO_2$와 $CH_4$를 활용하여 부가가치가 높은 물질인 CO와 $H_2$를 얻을 수 있는 유망한 온실가스 감축 기술이다. 그러나 이 반응이 일어나는 반응기의 운전 중에 심각한 코킹 문제가 발생할 수 있다. 이산화탄소 개질반응은 매우 강한 흡열반응이기 때문에 반응기 입구 근처에서 반응 온도가 많이 떨어지면서 코크 생성을 야기시킨다. 이러한 문제를 해결하기 위해서는 코크 생성이 잘 일어나지 않는 온도영역에서 반응이 일어나도록 하는 것이 중요하다. 본 연구에서는 새로운 촉매 배열 방법을 이용하여 반응기 전 구간이 코크 생성이 잘 일어나지 않는 온도 영역 내에서 유지되도록 하는 설계 방법을 제안하였다. 이 설계 방법은 연료 유량, 촉매 밀도, 구간 별 출구 온도를 최적화 변수로 하여 주어진 전환율에 대하여 반응기 길이를 최소화 할 수 있는 최적화 문제를 풀도록 하여 반응기를 최적화한다.