• Journal of Plant Biotechnology
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• 제36권4호
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• pp.320-326
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• 2009

The carbon dioxide concentration of the atmosphere is projected to increase by almost 50% over the first 50 years of this century. The major cause of this increase is continued combustion of fossil fuels. As a result, the significant changes in climate that have already occurred will be amplified, in particular a global temperature increase. Renewable energy production has a central role to play in abating net $CO_2$ emissions to a level that will arrest the development of global warming. Especially, biomass crops are becoming increasingly important as concerns grow about climate change and the need to replace carbon dioxideproducing fossil fuels with carbon-neutral renewable sources of energy. To succeed in this role, biomass crop has to grow rapidly and yield a reliable, regular harvest. A prime candidate is Miscanthus, or Asian elephant grass, a perennial species that produces over 3 metres of bamboo-like stems in a year. Miscanthus species are typically diploid or tetraploid. Hybrids between species with different ploidy levels result in the highly productive triploid hybrids, M. ${\times}$ giganteus. Here we will detail the Miscanthus characteristics desired of a biomass fuel crop.

• 한국해양바이오학회지
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• 제11권1호
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• pp.23-28
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• 2019

For successful microalgal biodiesel production, the strain should be selected carefully. Fast growth rate and high fatty acid contents are desired traits for algal biodiesel production. In ocean cultivation of microalgae, seawater temperature slowly changes over seasons, and rotating algal strains in accordance with their optimal temperature could improve overall productivity. Additionally, use of indigenous strain is preferred to alleviate potential impacts on the environment. In this study, five strains of Tetraselmis sp. from nearshore of Youngheung Island, Incheon, Korea, were isolated during winter and characterized for their growth patterns and fatty acid compositions in the low temperatures ($5-15^{\circ}C$). The five strains showed various characteristics in optimal growth temperature, fatty acid contents, and compositions. Compared with a strain of Tetraselmis sp., isolated from Ganghwa island in a previous study, a rapid-growing strain with 237% higher biomass productivity and an oleaginous strain with twice higher fatty acid contents at $10^{\circ}C$ were isolated. The oleaginous Tetraselmis strain showed the highest fatty acid productivity among the strains, having 438% higher productivity than the previous strain. Using the new isolates in the seasons with low seawater temperature would improve microalgal fatty acid productivity in ocean cultivation.

• Journal of Microbiology and Biotechnology
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• 제25권7호
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• pp.1114-1118
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• 2015

Microbial fuel cells (MFCs) have gathered attention as a novel bioenergy technology to simultaneously treat wastewater with less sludge production than the conventional activated sludge system. In two different operations of the MFC and aerobic process, microbial growth was determined by the protein assay method and their biomass yields using real wastewater were compared. The biomass yield on the anode electrode of the MFC was 0.02 g-COD-cell/gCOD-substrate and the anolyte planktonic biomass was 0.14 g-COD-cell/g-COD-substrate. An MFC without anode electrode resulted in the biomass yield of 0.07 ± 0.03 g-COD-cell/g-CODsubstrate, suggesting that oxygen diffusion from the cathode possibly supported the microbial growth. In a comparative test, the biomass yield under aerobic environment was 0.46 ± 0.07 g-COD-cell/g-COD-substrate, which was about 3 times higher than the total biomass value in the MFC operation.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.511-511
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• 2009

Lignocellulosic biomass is the most abundant organic material on earth and also promising raw material for bioenergy production. Agricultural residues in the process of bio-oil extraction, is an abundant and low-cost lignocellulosic material. The technology for conversion of lignocellulosic biomass resources to fuels and chemicals, such as ethanol, has been under development for decades. One of the well-studied technologies that are currently being commercialized is to use a dilute acid-catalyzed pretreatment followed by enzymatic hydrolysis and fermentation to produce ethanol. In this work, the dilute-acid hydrolysis of agricultural residues was optimized through the utilization of statistical experimental design. Evaluation criteria for optimization of the pretreatment conditions were based on high xylose recovery and low inhibitor contents in the hydrolyzates. The purpose of this study was to gain a more accurate understanding of the quantities of acid required for effective hydrolysis and the reactivity trade-offs with reaction time and temperature that will enable overall process optimization.

• 한국작물학회지
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• 제61권3호
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• pp.215-221
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• 2016

바이오에너지용 억새의 트랙터 부착 수확기 등 중장비 동원 늦은 수확에 따른 부작용을 구명하기 위해 전년도 생육 줄기의 늦은 수확 시기별 당년 생육특성과 마른줄기 수량을 구명한 결과는 다음과 같다. 1. 시험포장의 지하 10 cm 토양 경도는 맹아시, 맹아기, 맹아종 수확에서 각각 650, 793, 735 kPa로 일정한 경향이 없었으나 지하 20 cm에서는 각각 741, 915, 1,045 kPa로 늦게 수확할수록 단단해 졌다. 2. 이질 3배체에 비해 거대1호가 생육시기별 경수의 변이폭이 컸다. 거대 1호는 수확 시기별로 가장 늦은 맹아종에서 생육중기(5월 22일)에 169개/$m^2$로 가장 많았으나 생육 최성기(7월 22일)에 70개/$m^2$로 급격히 감소하였다. 3. 수확시기가 늦을수록 당년 생성된 지하경이 전년의 것에 비해 가늘어져 맹아종 수확에서 전년, 당년생성 지하경태가 거대 1호는 각각 9.2 mm, 6.7 mm 이질 3배체는 각각 8.5 mm, 8.0 mm였다. 4. 수확시기가 늦을수록 경장이 작아지고 아울러 줄기수량도 감소하였다. 거대1호와 이질3배체의 경장은 맹아시 수확에서 각각 308 cm, 374 cm였으나 맹아종 수확에서는 각각 268 cm, 341 cm로 작아졌다. 줄기 수량 또한 맹아시 수확에서는 각각 1,440 kg/10a, 1,777 kg/10a였으나 맹아종 수확에서는 각각 847 kg/10a, 963 kg/10a로 크게 감소하였다. 5. 출수율은 거대 1호의 경우 맹아시 수확에서 3.9%로 극히 낮았고, 맹아기 및 맹아종 수확에서는 거의 출수되지 않았다. 이질3배체는 맹아시 수확에서 49.6%였고, 맹아기, 맹아종에서도 각각 40.6%, 21.8% 수준을 유지하였다.

• KSBB Journal
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• 제24권3호
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• pp.296-302
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• 2009

질산화 미생물은 환경조건에 대단히 민감하여 질산화 영향인자의 변화에 의하여 미생물의 성장과 활동이 좌우되고, 이에 의해 질산화 공정의 성공여부가 좌우된다. 질산화에 영향을 미치는 인자로는 배양온도, pH, 용존산소, 기질량, C/N비, 미생물량 등이 있다. 본 연구에서는 폐수처리장의 활성슬러지를 이용하여 합성폐수의 질산화 공정에 미치는 인자들에 대한 연구를 수행하여 다음과 같은 결론을 얻었다. 고농도의 암모니아성 질소(100 mg/L 이상)를 함유한 경우에 있어서는 합성폐수의 pH가 초기 8에서 pH 6.8까지 감소하였다. 이는 질산화 과정을 통하여 아질산성 질소와 질산성 질소가 생성되어 합성폐수 중의 pH 변화를 가져온 것으로 판단된다. 질산화 공정에서 각각 초기 암모니아성 질소 농도, 공급공기량, 접종한 활성슬러지 양에 비례해서 일정구간에서는 암모니아성 질소의 제거속도가 증가하였다. 질산화 공정에서 C/N 비의 영향은 일정 C/N 비 범위에서는 탄소원이 존재할수록 초기에 암모니아성 질소의 제거율이 증진되는 결과를 얻었다.

• 한국작물학회지
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• 제65권1호
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• pp.72-78
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• 2020

본 연구는 탄질비(C/N)가 224인 억새 절삭물을 토양에 시용하여 토양을 개선하고 작물 생육을 촉진하고자 ha 당 무시용, 10톤, 20톤을 처리하였다. 그 결과, 토양 유기물 함량이 시험 전 11.0 g·kg^-1에서 3년 후 최대 16.3까지 증가하였다. 토양 양이온치환용량의 경우 3년 후 최대 15.3 cmol_c·kg^-1까지 증가하였다. 앞그루작물인 단수수는 20톤 시용구가 줄기가 굵었고 주당 착즙량이 60 ml로 가장 많았다. 착즙액량과 착즙액의 가용성고형물 함량을 곱한 수량지수는 억새 10톤 시용구가 1,913으로 가장 높고 20톤 시용구와 대조구가 각각 1,851, 1,839 순이었다. 억새 바이오매스 시용량이 늘어나고 시험 연차가 길어짐에 따라 일시적 비절과 가뭄 피해가 발생하였다. 고구마 지상부 생육은 억새 시용의 영향을 받지 않았다. 상품(marcketable) 괴근 수는 억새 20톤 시용구가 대조구와 같은 2,9개였고, 10톤 시용구가 3.6개로 가장 많았다. 억새 20톤 시용구와 대조구의 2년간 평균수량이 각각 2,579 kg/10a, 2,708으로 낮았고 10톤 시용구가 3,289로 가장 많았다. 뒷그루작물인 양파의 경우 억새 시용에 따른 수량 차이는 인정되지 않았으나 억새 20톤 시용구가 무시용구나 10톤 시용구에 비해 양파 초장과 엽장이 길었다. 마늘의 수량은 2,630~2,901 kg/10a으로서 억새 시용의 영향이 없었고, 억새 10톤 시용구가 초장과 엽장이 가장 길었고, 인편 수는 억새 시용구가 인경구당 8.2~8.3개였고 대조구가 8.9개로 가장 많았다. 본 시험 결과, ha 당 10톤 내외의 억새 바이오매스를 시용할 경우 토양 개량과 더불어 작물 생육과 수량을 촉진시켜 향후 부존자원인 억새의 가치를 재발견하는 실마리가 될 것으로 보인다.

• Environmental Engineering Research
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• 제24권2호
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• pp.271-278
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• 2019

Mass cultivation of microalgae is necessary to achieve economically feasible production of microalgal biodiesel. However, the high cost of nutrients is a major limitation. In this study, corncob extract (CCE) was used as an inorganic and organic nutrient source for the mass cultivation of Chlorella vulgaris (C. vulgaris). Chemical composition analysis of CCE revealed that it contained sufficient nutrients for mixotrophic cultivation of C. vulgaris. The highest specific grow rate of C. vulgaris was obtained at pH of 7-8, temperature of $25-30^{\circ}C$, and CCE amount of 5 g/L. In the analysis using various growth models, Luong model was found to be the most suitable empirical formula for mass cultivation of C. vulgaris using CCE. Analysis of biomass and production of triacyglycerol showed that microalgae grown in CCE medium produced more than 17.23% and 3% more unsaturated fatty acids than cells cultured in Jaworski's Medium. These results suggest that growing microalgae in CCE-supplemented medium can increase lipid production. Therefore, CCE, agricultural byproduct, has potential use for mass cultivation of microalgae.

• 펄프종이기술
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• 제44권4호
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• pp.32-42
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• 2012

Wood biomass including forest residues, waste wood, and construction residuals has been widely generated in Korea, but forest biomass from the National Forest Management Operation Project plays a big role in generating wood biomass. Unfortunately the promotion policy of woody energy organized by the Forest Service in Korea concentrates more on demand creation rather than on supply expansion. Therefore, in order to utilize insufficient wood resources effectively, it is greatly required to develop uses for maximizing their added value. In particular, more attention to the use of the second generation biomass has been paid in foreign countries because there is a threshold that the first generation biomass cannot produce enough biofuel without threatening food supplies and biodiversity. In Korea, wood pellets are regarded as the alternative clean fuels to oils and coals that emit green house gases into the atmosphere. However, using wood as pellet raw materials can not be an economic way because the value of wood disappears right after burning in the boiler in spite of its contribution to the decrease of carbon emission. Differently from wood pellets, kraft pulping process using woody biomass produces black liquor as a by-product which can be used to generate electricity, bioenergy and biochemicals through gasification. Thus, it can be more economical to make a torrefaction of lignocellulosic biomass such as low-quality wood and agricultural leftovers as raw materials of pellets.

• Journal of Microbiology and Biotechnology
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• 제28권2호
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• pp.267-274
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• 2018

Lipids in microalgae are energy-rich compounds and considered as an attractive feedstock for biodiesel production. To redirect carbon flux from competing pathways to the fatty acid synthesis pathway of Tetraselmis sp., we used three types of chemical inhibitors that can block the starch synthesis pathway or photorespiration, under nitrogen-sufficient and nitrogen-deficient conditions. The starch synthesis pathway in chloroplasts and the cytosol can be inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 1,2-cyclohexane diamine tetraacetic acid (CDTA), respectively. Degradation of glycine into ammonia during photorespiration was blocked by aminooxyacetate (AOA) to maintain biomass concentration. Inhibition of starch synthesis pathways in the cytosol by CDTA increased fatty acid productivity by 27% under nitrogen deficiency, whereas the blocking of photorespiration in mitochondria by AOA was increased by 35% under nitrogen-sufficient conditions. The results of this study indicate that blocking starch or photorespiration pathways may redirect the carbon flux to fatty acid synthesis.