• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.101-101
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• 2010

Anaerobic digestion(AD) is the most promising method for treating and recycling of different organic wastes, such as organic fraction of municipal solid waste, household wastes, animal manure, agro-industrial wastes, industrial organic wastes and sewage sludge. During AD, i.e. organic materials are decomposed by anaerobic forming bacteria and fina1ly converted to excellent fertilizer and biogas which is a mixture of carbon dioxide and methane. AD has been one of the leading technologies that can make a large contribution to produce renewable energy and to reduce $CO_2$ and other green-house gas(GHG) emission, it is becoming a key method for both waste treatment and recovery of a renewable fuel and other valuable co-products. Currently some 80% of the world's overall energy supply of about 400 EJ per year in derived from fossil fuels. Nevertheless roughly 10~15% of this demand is covered by biomass resources, making biomass by far the most important renewable energy source used to date. The representative biofuels produced from the biomass are bioethanol, biodiesel and biogas, and currently biogas plays a smaller than other biofuels but steadily growing role. Traditionally anaerobic digestion applied for different biowaste e.g. sewage sludge, manure, other organic wastes treatment and stabilization, biogas has become a well established energy resource. However, the biowaste are fairly limited in respect to the production and utilization as renewable source, but the plant biomass, the so called "energy crops" are used for more biogas production in EU countries and the investigation on the biomethane potential of different crops and plant materials have been carried out. In Korea, with steadily increasing oil prices and improved environmental regulations, since 2005 anaerobic digestion was again stimulated, especially on the biogasification of different biowastes and agro-industrial biomass including "energy crops". This study have been carried out to investigate anaerobic biodegradability by the biochemical methane potential(BMP) test of animal manures, different forage crops i.e. "energy crops", plant and industrial organic wastes in the condition of thermophilic temperature, The biodegradability of animal manure were 63.2% and 58.2% with $315m^3CH_4/tonVS$ of cattle slurry and $370m^3CH_4/tonVS$ of pig slurry in ultimate methane yields. Those of winter forage crops were the range 75% to 87% with ultimate methane yield of $378m^3CH_4/tonVS$ to $450m^3CH_4/tonVS$ and those of summer forage crops were the range 81% to 85% with ultimate methane yield of $392m^3CH_4/tonVS$ to $415m^3CH_4/tonVS$. The forge crops as "energy crops" could be used as good renewable energy source to increase methane production and to improve biodegradability in co-digestion with animal manure or only energy crop digestion.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.588-598
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• 2017

Currently, bioethanol, a fuel additive for transportation, is produced mainly by using biomass (first generation) such as corn and sugar canes. First generation biomass can cause various problems in terms of increase in agricultural prices and ethical reasons. To address these problems, a nonedible lignocellulosic biomass can be utilized. Agricultural byproducts such as straw, bagasse, and forest byproducts from the wood processing industry. Therefore, production of wood based bioethanol can be an effective utilization route of second generation biomass, and its raw materials are more abundant than first generation resources. Furthermore, it is possible to secure cheap raw materials. One of the biggest advantages of using biofuels is that it contributes to the reduction of greenhouse gases by minimizing the environmental impact, unlike fossil fuels. In this study, we investigated the greenhouse gas reduction effects that can be achieved through the use of Lignocellulosic bioethanol and government policies on renewable energy currently being implemented in ASEAN countries (Indonesia, Malaysia, Thailand and the Philippines). In these four countries, policies and incentives related to biofuels have been developed. It is expected that the reduction ratio of carbon dioxide emission and the mixed biofuel will be gradually increased in the future.

• Journal of Plant Biotechnology
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• v.37 no.1
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• pp.25-46
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• 2010

The demand for fuel and energy resources continues to grow due to increased consumption and emerging economies in all parts of the world. With this increase in demand, crude oil prices in the international market has jumped dramatically. Global warming, which is a consequence of increasing greenhouse gas (GHG) emissions, has become scientific, social, and political concerns. To cope with global warming and energy crisis, cost-competitive biofuels are urgently needed. In addition, development of an infrastructure, which supplies energy stably and diversifies energy resources, as well as new cost-saving technologies should be developed to reduce the costs of producing biofuels. Due to high oleic acid content, rapeseed (Brassica napus L.) is currently the potential feedstock for biodiesel production in temperate zone region and the production and use of rapeseed oil is already commercialized in Europe. In Korea double-cropping (rice and rapeseed) became more prevalent because it reduces competitions from land constraints. Production of rapeseed as a biodiesel feedstock may reduce the influence of rising oil prices and nation's dependence on imported petroleum and increase job opportunities and farm incomes.

• Clean Technology
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• v.27 no.2
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• pp.190-197
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• 2021

Kraft lignin is a by-product of the pulp and paper industry, obtained as a black liquor after the extraction of cellulose from wood through the Kraft pulping process. Right now, kraft lignin is utilized as a low-grade boiler fuel to provide heat and power but can be converted into high-calorific biofuels or high-value chemicals once the efficient catalytic depolymerization process is developed. In this work, the multi-functional catalyst of Ru-Mg-Al-oxide, which contains hydrogenation metals, acid, and base sites for the effective depolymerization of kraft lignin are prepared, and its lignin depolymerization efficiency is evaluated. In order to understand the role of different active sites in the lignin depolymerization, the three different catalysts of MgO, Mg-Al-oxide, and Ru-Mg-Al-oxide were synthesized, and their lignin depolymerization activity was compared in terms of the yield and the average molecular weight of bio-oil, as well as the yield of phenolic monomers contained in the bio-oil. Among the catalysts tested, the Ru-Mg-Al-oxide catalyst exhibited the highest yield of bio-oil and phenolic monomers due to the synergy between active sites. Furthermore, in order to maximize the extent of lignin depolymerization over the Ru-Mg-Al-oxide, the effects of reaction conditions (i.e., temperature, time, and catalyst loading amount) on the lignin depolymerization were investigated. Overall, the highest bio-oil yield of 72% and the 3.5 times higher yield of phenolic monomers than that without a catalyst were successfully achieved at 350 ℃ and 10% catalyst loading after 4 h reaction time.

• KSBB Journal
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• v.26 no.4
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• pp.347-351
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• 2011

In this study, we investigated the effect of reaction factors on enzymatic hydrolysis of Hizikia fusiforme, which is brown algae in marine biomass resource, using commercial enzymes. The composition of H. fusiforme is 38.9% of reducing sugar, 4.8% of moisture, 17.8% of ash, and 38.5% of others. In the condition of 1-5% substrate, the increase of substrate concentration enhanced the increase of reducing sugar formation; however, the hydrolysis yield did not increase after 24 h. After reaction of 75 h, conversion yield of reducing sugar were obtained to 16.45%, 17.99%, and 14.55% at 1, 2.5, and 5% substrate, respectively. As a result of effect of enzyme amount, the formation of reducing sugar did not show considerable change at 1% substrate. However, in the condition of 2.5% substrate, the great change of reducing sugar formation was observed by the increase of enzyme amount. The conversion yields of reducing sugar were obtained to 18.77% and 22.83% at 1% and 2.5% substrate with 30% enzyme, respectively. As a result of heat treatment of biomass, the high yield was obtained in 2.5% substrate and the yields were increased to 0.06-7.2% by the heat treatment. This result will provide the basic information for production process of biofuels and chemicals from marine biomass H. fusiforme.

• Environmental Engineering Research
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• v.23 no.1
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• pp.46-53
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• 2018

This study explores the environmentally innovative and low-impact technology, a zero food waste system (ZFWS) that utilizes food waste and converts it into composts or biofuels and curtails carbon emissions. The ZFWS not just achieves food waste reductions but recycles food waste into fertilizer. Based on a fermentation-extinction technique using bio wood chips, the ZFWS was employed in a field experiment of the system installed in a large-scale apartment complex, and the performance of the system was examined. The on-site ZFWS consisted of three primary parts: 1) a food waste slot into which food waste was injected; 2) a fermentation-extinction reactor where food waste was mixed with bio wood chips made up of complex enzyme and aseptic wood chips; and 3) deodorization equipment in which an ultraviolet and ozone photolysis method was employed. The field experiment showed that food waste injected into the ZFWS was reduced by 94%. Overall microbial activity of the food waste in the fermentation-extinction reactor was measured using adenosine tri-phosphate (ATP), and the degradation rate of organic compounds, referred to as volatile solids, increased with ATP concentration. The by-products generated from ZFWS comply with the national standard for organic fertilizer.

• ALGAE
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• v.28 no.1
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• pp.93-99
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• 2013

A freshwater cyanobacterium, Phormidium autumnale KNUA026, was isolated from puddles of icy water in Gyeongsan City, South Korea and its potential as a biofuel feedstock was investigated. Maximal growth was obtained when the culture was incubated at $25^{\circ}C$ and around pH 9.0. The total lipid content of the isolate was approximately 14.0% of dry weight and it was found that strain KNUA026 was able to autotrophically synthesize heptadecane ($C_{17}H_{36}$) which can be directly used as fuel without requiring a transesterification step. As this benthic cyanobacterium was capable of forming thick mats, it could be easily harvested by gravitational settling and this property may reduce the cost of production in commercial applications. Hence, P. autumnale KNUA026 appears to be a promising resource for use in the production of microalgae-based biofuels.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.5
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• pp.499-506
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• 2010

Recently, a great deal of attention have been directed to the use of alternative fuels as a means to reduce vehicular emissions. As one of the promising alternative fuels, bio-diesel has advantages of a wide adaptability without retrofit of diesel engine. It is also effective enough to reduce CO, THC, $SO_x$, polycyclic aromatic hydrocarbons (PAHs) and PM. In this study, we investigated the emission characteristics of biofuels between different operating conditions, i.e., engine speed (1,400 rpm and 2,300 rpm), engine load (10% and 100%), bio-diesel blending (BD0, BD5 and BD20), and recirculation (EGR) rate of exhaust gas (0% and 20%). Relative performance of the system was evaluated mainly for the greenhouse gases ($CH_4$, $N_2O$ and $CO_2$). In addition, emission characteristics of ND-13 mode were also tested against both greenhouse gases and other airborne pollutants under emission regulation. The relative composition of bio-diesel has shown fairly clear effects on the emission quantities of CO, THC, and PM emission, although it was not on $NO_x$ and greenhouse gases. EGR rate has shown trade-off characteristics between $NO_x$ and PM.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.4
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• pp.25-32
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• 2009

Forest biomass can be used as various types of raw materials such as pulp, wood pellets, solid charcoals and so on. This paper estimates the nation wide amount of forest biomass based on the projection of forest areas for its effective and economic use. Several trend equations are used in projecting the forest areas. In 2009, the forest biomass arising from thinning is estimated be 6,591,575 $m^3$. The estimates of forest biomass in 2015 and 2018 are 6,375,627 $m^3$ and 6,284,779 $m^3$, respectively. Since the forest areas are projected to be declining, the biomass generated by thinning will decrease. This implies that the new alternatives for supplying raw materials for biofuels must be prepared before then.

• KSBB Journal
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• v.30 no.3
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• pp.125-131
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• 2015

Kluyveromyces marxianus is a well-known thermotolerant yeast. Although Saccharomyces cerevisiae is the most commonly used yeast species for ethanol production, the thermotolerant K. marxianus is more suitable for simultaneous saccharification and fermentation (SSF) processes. This is because enzymatic saccharification usually requires a higher temperature than that needed for the optimum growth of S. cerevisiae. In this study, we compared the fermentation patterns of S. cerevisiae and K. marxianus under various temperatures of fermentation. The results show that at a fermentation temperature of $45^{\circ}C$, K. marxianus exhibited more than two fold higher growth rate and ethanol production rate in comparison to S. cerevisiae. For SSF using starch or corn stover as the sole carbon source by K. marxianus, the high temperature ($45^{\circ}C$) fermentations showed higher enzymatic activities and ethanol production compared to SSF at $30^{\circ}C$. These results demonstrate the potential of the thermotolerant yeast K. marxianus for SSF in the industrial production of biofuels.