• Journal of Korean Society of Forest Science
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• v.98 no.4
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• pp.409-416
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• 2009

Forest biomass estimation is essential for greenhouse gas inventories and terrestrial carbon accounting. Remote sensing allows for estimating forest biomass over a large area. This study was conducted to estimate forest biomass and to produce a forest biomass map for Muju county using forest biomass conversion table developed by field plot data from the 5th National Forest Inventory and Landsat TM-5. Correlation analysis was carried out to select suitable independent variables for developing regression models. It was resulted that the height class, crown closure density, and age class were highly correlated with forest biomass. Six regression models were used with the combination of these three stand variables and verified by validation statistics such as root mean square error (RMSE) and mean bias. It was found that a regression model with crown closure density and height class (Model V) was better than others for estimating forest biomass. A biomass conversion table by model V was produced and then used for estimating forest biomass in the study site. The total forest biomass of the Muju county was estimated about 8.8 million ton, or 128.3 ton/ha by the conversion table.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.4
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• pp.86-94
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• 2015

Torrefaction is a thermochemical process proceeded at the temperature around $250^{\circ}C$ in an inert gas condition. By torrefaction, the hemicellulose portions contained in biomass are broken down to change into the volatile gas which is removed from biomass eventually. The main purpose of biomass torrefaction is to improve the energy density of the biomass to minimize the transport energy consumption, though the flammability can be elevated for transportation. In this study two types of solid biomass fuel, waste wood and rice straw, were torrefied at various temperature range from $200^{\circ}C$ to $300^{\circ}C$ to evaluate the torrefied biomass characteristics. In addition torrefied biomass were tested to evaluate the combustion characteristics using TGA (Thermogravimetric Analysis). After the torrefaction of biomass, the C/H (carbon to hydrogen ratio) and C/O (carbon to oxygen ratio) were measured for aquisition of bio-stability as well as combustion pattern. Generally C/H ratio implies the soot formation during combustion, and the C/O ratio for bio-stability. By torrefaction temperature at $300^{\circ}C$, C/H ratio and C/O ratio were increased by two times for C/H and three times for C/O. The torrefied biomass showed similar TGA pattern to coal compared to pure biomass; that is, less mass decrease at lower temperature range for torrefied biomass than the pure biomass.

• Journal of Microbiology and Biotechnology
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• v.30 no.10
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• pp.1467-1479
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• 2020

Profiling the transcriptome changes involved in xylose metabolism by the fungus Trichoderma reesei allows for the identification of potential targets for ethanol production processing. In the present study, the transcriptome of T. reesei HJ-48 grown on xylose versus glucose was analyzed using next-generation sequencing technology. During xylose fermentation, numerous genes related to central metabolic pathways, including xylose reductase (XR) and xylitol dehydrogenase (XDH), were expressed at higher levels in T. reesei HJ-48. Notably, growth on xylose did not fully repress the genes encoding enzymes of the tricarboxylic acid and respiratory pathways. In addition, increased expression of several sugar transporters was observed during xylose fermentation. This study provides a valuable dataset for further investigation of xylose fermentation and provides a deeper insight into the various genes involved in this process.

• Journal of agriculture & life science
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• v.44 no.5
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• pp.45-53
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• 2010

This study was conducted to examine the biomass and net primary production, stem density and biomass expansion factors of Pinus densiflora in Gochang regions. The mean age of Pinus densiflora in both stands was 10 and 48 years. The dry weights (kg/tree) and aboveground biomass (Mg/ha) were 8.59 and 17.55 for 10 years young stand, 166.66 and 122.05 for 48 years old stand. The total biomass (Mg/ha) including the above and belowground were 21.48 and 154.16 in both age stands. The proportion of stem biomass, stem bark biomass and root biomass increased from the young stand to the old stand while on the leaf biomass and branch biomass, tend to decreased. The net primary production of aboveground biomass (Mg/ha) and belowground biomass were 6.30~6.95 for the young stand and 11.61~13.19 for old stand. The stem density ($g/cm^3$) was 0.338 for young stand while on the other hand, 0.448 for old stand was observed. The above and total biomass expansion factors were 2.304~2.508 and 1.318~1.644 in each age stands, respectively.

• Journal of Forest and Environmental Science
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• v.25 no.2
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• pp.131-138
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• 2009

Recently, various efforts for the extended utilization of woody biomass has been attempted due to the fact that global warming, energy and environmental problems are urgent ones to be solved. Development of new energy sources at our national security level is desperately needed as we depend on almost all of energies supplied from other countries, let alone the economic crisis caused by oil price hike. Woody biomass can be converted to energy by means of thermochemical, biological, or direct combustion processes. Many processes are available for producing bioenergy, such as bioethanol, wood pellet, wood chip, combined heat, and power system. Political support and R&D investment should be provided that can boost the utilization of the wood biomass, the eco-environment, and recyclable and alternative energy resources for national power security. In addition, a long-term strategy that can utilize unused and low efficient woody biomass resources, and systematically collect and manage them in a national level should be set up. Even though the possibility in total exchange of fossil oil with woody biomass is quite low, technology developments of woody biomass for the solution to global warming and environmental problem through its commercialization are expected to grow steadily.

• Journal of Forest and Environmental Science
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• v.29 no.1
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• pp.81-89
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• 2013

Nowadays, excessive using of fossil fuel contributes to global warming. Also, this phenomenon increases steadily. Therefore forest biomass from logging residues has received attention. The goal of this study was to determine the sustainability and economic feasibility of forest-biomass energy source. Accordingly, forest biomass resource was calculated, and harvesting and transporting machines which can be used in investing area were chosen, when using forest biomass as energy source. And then through these data, the harvesting cost was decided. The forest biomass resource calculated, thinned trees and logging residues, was 37,330.23 $m^3$ and 14,073.60 ton, respectively. When harvesting timber in each sub-compartment, the average thinned trees yield was 120.73 $m^3$, and tree logging residues was 402.80 ton. The use of tower yarder as harvesting and transporting equipments in study area was 85.4% and 66.7%, respectively, in up hill and down hill yarding. The average harvesting cost of biomass in the possibility area of timber yarding operation was expensive as 81,757 won/$m^3$, 85,434 won/m3 and 50,003 won/ton, respectively, in thinned trees and logging residue. If using data from this research analysis, tree could be felled by choosing sub-compartment.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.1
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• pp.122-131
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• 2020

To reduce emissions from coal-fired power plants, researchers focusing on coal and biomass co-firing technology. Biomass, with its carbon-neutral nature and lower quantities of nitrogen and sulfur compared with coals, has a positive impact on coal-fired power generation. Many studies on the combustion of biomass have been conducted, but the study on the combustion characteristics of biomass char is limited. FERPM predicts char combustion characteristics with high accuracy by introducing experimental data-based parameters of biomass char and has not yet been applied in numerical simulation. In this study, FERPM is numerically applied to char combustion of wood pellets representing wood-based biomass and the combustion characteristics are compared with the kinetic/diffusion limited model, intrinsic model, and diffusion limited model.

• Journal of Environmental Science International
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• v.7 no.1
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• pp.112-115
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• 1998

During the spring and fall of 1994 and winter of 1995, the exposure time of periphyton biomass on terval. In the streams with low periphyton biomass (chi. a: 2-4 mg/$m^2$) in natural rocks, biomass of arttificial substrata (unglazed tile: $3.7{\times}9.5{\times}2 cm$) exceeded that of the natural rocks after 28 days, while sites with high biomass (chi. a: 20-60 mg/$m^2$) in natural rocks showed slower biomass accumulation after 40 days. Due to the high licht input and temperature in a Partially shaded mountain stream, development of periphyton biomass in spring occurred faster than that of winter. In general, development of periphyton biomass placed on artificial substrata took 4-5 weeks in spring and at least 6 weeks In winter to reach the natural level.

• Biotechnology and Bioprocess Engineering:BBE
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• v.2 no.2
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• pp.126-131
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• 1997

The biosorption and desorption of Cr, Cu and Al were carried out using brown marine algae Sargassum fluitans biomass, known as the good biosorbent of heavy metals. The content of alginate bound to light metals could be changed by physical and chemical pretreatment. The maximum uptake of Cr, Cu and Al was independent of the alginate content. The maximum uptaker of Al was two times(mole basis) than those of Cu and Cr. The aluminum-alginate complex was found in the sorption solution of raw and protonated biomass. Most of Cu, Al and light metals sorbed in the biomass were eluted at pH 1.1. However, only 5 to 10% of Cr sorbed was eluted at pH 1.1. The stoiceometric ion exchange between Cu and Ca ion was observed on Cu biosorption with Ca-loaded biomass. A part of Cr ion was bound to biomass as Cr(OH)2+ or Cr(OH)2+. Al was also bound to biomass as multi-valence ion and interfered with the desorbed Ca ion. The behavior of raw S. fluitans in ten consecutive sorption-desorption cycles has been investigated in a packed bed flow-through-column during a continuous removal of copper from a 35 mg/L aqueous solution at pH 5. The eluant used was a 1%(w/v) CaCl2/HC solution at pH 3.

• Journal of Microbiology and Biotechnology
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• v.21 no.3
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• pp.293-298
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• 2011

Nitrifying bacterial community structures of suspended and attached biomasses in a full-scale integrated fixed-film activated sludge process were investigated by analyzing 16S rRNA gene sequences obtained from pyrosequencing. The suspended biomass had a higher number of ammonia-oxidizing bacterial sequences (0.8% of total sequences) than the attached biomass (0.07%), although most of the sequences were within the Nitrosomonas oligotropha lineage in both biomasses. Nitrospira-like nitrite-oxidizing bacterial sequences were retrieved in the suspended biomass (0.06%), not in the attached biomass, whereas the existence of Nitrobacter-like sequences was not evident. The suspended biomass had higher nitrification activity (1.13 mg N/TSS/h) than the attached biomass (0.07 mg N/TSS/h). Overall, the results made it possible to conclude the importance of the suspended biomass, rather than the attached biomass, in nitrification in the wastewater treatment process studied.