• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.4
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• pp.445-451
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• 2012

We developed an age-based spawner-recruit model incorporating environmental variables to forecast stock biomass and recruits of pelagic fish in this study. We applied the model to the Tsushima stock of jack mackerel, which is shared by Korea and Japan. The stock biomass of jack mackerel (Trachurus japonicus) around Korean waters ranged from 141 thousand metric tons (mt) and 728 thousand mt and recruits ranged from 27 thousand mt to 283 thousand mt. We hind-casted the stock biomass to evaluate the model performance and robustness for the period of 1987~2009. It was found that the model has been useful to forecast stock biomass and recruits for the period of the lifespan of fish species. The model is also capable of forecasting the long-term period, assuming a certain climatic regime.

• Journal of Korea Society of Waste Management
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• v.35 no.7
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• pp.640-646
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• 2018

Biomass-fired power plants produce electricity and heat by burning biomass in a boiler. However, one of the most serious problems faced by these plants is severe corrosion. In biomass boilers, corrosion comes from burnt fuels containing alkali, chlorine, and other corrosive substances, causing boiler tube failures, leakages, and shorter lifetimes. To mitigate the problem, various approaches implying the use of additives have been proposed; for example, ammonium sulfate is added to convert the alkali chlorides (mainly KCl) into the less corrosive alkali sulfates. Among these approaches, the high temperature corrosion prevention technology based on ammonium sulfate has few power plants being applied to domestic power plants. This study presents the results obtained during the co-combustion of wood chips and waste in a circulating fluidized bed boiler. The aim was to investigate the characteristics of pollution load in domestic biomass power plants with ammonium sulfate injection. By injecting the ammonium sulfate, the KCl content decreased from 68.9 to 5 ppm and the NOx were reduced by 18.5 ppm, but $SO_2$ and HCl were increased by 93.3 and 68 ppm, respectively.

• Journal of Korean Society of Forest Science
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• v.111 no.4
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• pp.603-612
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• 2022

The study aims were to evaluate a machine-learning, algorithm-based, forest biomass-estimation model to estimate subnational forest biomass and to comparatively analyze REDD+ forest reference emission levels. Time-series Landsat satellite imagery and ESA Biomass Climate Change Initiative information were used to build a machine-learning-based biomass estimation model. The k-nearest neighbors algorithm (kNN), which is a non-parametric learning model, and the tree-based random forest (RF) model were applied to the machine-learning algorithm, and the estimated biomasses were compared with the forest reference emission levels (FREL) data, which was provided by the Paraguayan government. The root mean square error (RMSE), which was the optimum parameter of the kNN model, was 35.9, and the RMSE of the RF model was lower at 34.41, showing that the RF model was superior. As a result of separately using the FREL, kNN, and RF methods to set the reference emission levels, the gradient was set to approximately -33,000 tons, -253,000 tons, and -92,000 tons, respectively. These results showed that the machine learning-based estimation model was more suitable than the existing methods for setting reference emission levels.

• Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.324-331
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• 2010

Seasonal variation in seaweed biomass was examined along vertical shore gradients on the rocky shores of Nachido and Odo Islands, the Yellow Sea, Korea, from August 2007 to April 2008. The average annual biomass of seaweed was 404.07 g wet wt/$m^2$, with seasonal variation from 232.61 g in the spring to 754.90 g wet wt/$m^2$ in the summer at Nachido Island. At Odo Island, average biomass was 270.82 g wet wt/$m^2$ and ranged from 48.35 g in the winter to 451.66 g wet wt/$m^2$ in the spring. Seaweed biomass exhibited an even distribution across the shore gradient from the high intertidal zone to -5 m depth at Nachido Island, whereas seaweed biomass was concentrated from the mid intertidal zone to -1 m depth in the subtidal zone at Odo Island. Sargassum thunbergii was the most dominant species, occupying 28.24% (114.12 g wet wt/$m^2$) and 36.57% (99.05 g wet wt/$m^2$) of total biomass at Nachido and Odo Islands, respectively. Subdominant seaweed species was Gelidium amansii, comprising 15.23% (61.52 g wet wt/$m^2$) and 14.70% (39.82 g wet wt/$m^2$) of total biomass at Nachido and Odo Islands, respectively. Dominant functional group was the coarsely branched-form group, which grows under moderate environmental conditions and comprised 93.34% (377.15 g wet wt/$m^2$) and 66.96% (181.35-g wet wt/$m^2$) of total biomass at Nachido and Odo Islands, respectively. Percentage biomass of sheet-form seaweeds growing at relatively disturbed and polluted areas was approximately 20.83% (56.40 g wet wt/$m^2$) of total biomass along the Odo rocky shore. Based on the biomass and functional-form composition of seaweeds, we concluded that Nachido Island provides better environmental conditions than does Odo Island. In addition, the vertical distribution and dominant species of seaweeds on the two islands were very similar, but the functional-form composition of seaweeds at Nachido Island differed slightly from that at Odo Island.

• Elastomers and Composites
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• v.46 no.3
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• pp.195-203
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• 2011

Eco-friendly materials or bio-composites were made with poly(lactic acid) (PLA) as matrix polymer and kenaf fibers as filler. Also, acetylated kenaf fibers and compatibilizer were adopted in order to improve the interfacial adhesion between fiber and polymer. In this study, the effect of chemical modification and compatibilizer on the mechanical-viscoelastic and morphology properties of the bio-composites was discussed. The hydrophobic fibers by acetylation were known to show better interfacial bonding with the matrix polymer and resulted in improved performance and morphology. Viscoelastic property and glass transition temperature, however, were not nearly enhanced.

• Journal of Korean Society of Forest Science
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• v.98 no.3
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• pp.311-318
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• 2009

This study purposed to construct supply and demand potential map of forest bioenergy with a GIS-based decision support system. The target areas of this study were a part of the forests in Yongdong region, Gangwondo, and most types of forests were pinus densiflora, pinus koreaiansis, and Oak. Data about forest type, age classes, the number of households, regional silviculture planning was stored in GIS to define the potential areas for supplying potential bioenergy from the forests, and to assess biomass available for a household. Theoretical potential biomass energy based on silviculture plan was estimated in average 3,144 Tcal, and this quantity will be enough to supply the quantity of demand of households in that area. However, if it assumed that average collecting rates of Kangwon province were 10%, the available quantity of biomass will be between 6% and 15% of demand. If the collecting rates were 60%, the supply of biomass could exceed the quantity of demand in certain cities.

• Journal of Korean Society of Forest Science
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• v.96 no.5
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• pp.591-601
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• 2007

Spatial information on forest biomass is an important factor to evaluate the capability of forest as a carbon sequestrator and is a core independent variable required to drive models which describe ecological processes such as carbon budget, hydrological budget, and energy flow. The objective of this study is to understand the relationship between satellite image and field data, and to quantitatively estimate and map the spatial distribution of forest biomass. Landsat Enhanced Thematic Mapper (ETM+) derived vegetation indices and field survey data were applied to estimate the biomass distribution of mountainous forest located in Gwangneung Experimental Forest (230 ha). Field survey data collected from the ground plots were used as the dependent variable, forest biomass, while satellite image reflectance data (Band 1~5 and Band 7), Normalized Difference Vegetation Index (NDVI), Soil-Adjusted Vegetation Index (SAVI), and RVI (Ratio Vegetation Index) were used as the independent variables. The mean and total biomass of Gwangneung catchment area were estimated to be about 229.5 ton/ha and $52.8{\times}10^3$ tons respectively. Regression analysis revealed significant relationships between the measured biomass and Landsat derived variables in both of deciduous forest ($R^2=0.76$, P < 0.05) and coniferous forest ($R^2=0.75$, P < 0.05). However, there still exist many uncertainties in the estimation of forest ecosystem parameters based on vegetation remote sensing. Developing remote sensing techniques with adequate filed survey data over a long period are expected to increase the estimation accuracy of spatial information of the forest ecosystem.

• New & Renewable Energy
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• v.17 no.1
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• pp.50-60
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• 2021

This study investigated the reference case in the UK where legality and sustainability were systematically established for forest biomass represented by wood pellets. The UK is the country that best utilizes the trade value of wood pellets based on sustainability, with bioenergy accounting for 31% of total renewable energy production. The UK imported wood pellet, estimated 8,697 thousand tons in 2019. The UK government has continuously improved the renewable generation policy system to ensure the sustainability of wood pellets. The weighted average greenhouse gas emissions of a UK biomass power plant that received a Renewable Obligation Certificate (ROC) in 2018-19 was 26.71 gCO2e/MJ. These power plants are expected to meet the upper limit of 72.2 gCO2e/MJ by 2025. To issue an ROC, the biomass power plant must demonstrate that 70% of its total biofuel usage is sustainable. The UK uses the Sustainable Biomass Program (SBP) certification system, which is gradually expanding to other European countries, to prove the sustainability of biomass energy fuels. Global wood pellet production with SBP certification in 2019 was 10.5 Mt. This trend has significant implications for introducing additional sustainability into the wood pellet policy of South Korea.

• Journal of Microbiology and Biotechnology
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• v.27 no.1
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• pp.1-8
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• 2017

The production of high-value chemicals from natural resources as an alternative for petroleum-based products is currently expanding in parallel with biorefinery. The use of lignocellulosic biomass as raw material is promising to achieve economic and environmental sustainability. Filamentous fungi, particularly Aspergillus species, are already used industrially to produce organic acid as well as many enzymes. The production of lignocellulose-degrading enzymes opens the possibility for direct fungal fermentation towards organic acids such as itaconic acid (IA) and fumaric acid (FA). These acids have wide-range applications and potentially addressable markets as platform chemicals. However, current technologies for the production of these compounds are mostly based on submerged fermentation. This work showed the capacity of two Aspergillus species (A. terreus and A. oryzae) to yield both acids by solid-state fermentation and simultaneous saccharification and fermentation. FA was optimally produced at by A. oryzae in simultaneous saccharification and fermentation (0.54 mg/g wheat bran). The yield of 0.11 mg IA/g biomass by A. oryzae is the highest reported in the literature for simultaneous solid-state fermentation without sugar supplements.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.6
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• pp.519-525
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• 2009

The catalytic steam reforming of woody biomass tar and soot to convert a synthetic gas containing hydrogen was investigated by using a bench-scale biomass gasification system. One commercial nickel-based catalyst, Katalco 46-6Q, and two different kinds of natural minerals, dolomite and olivine, were tested as a reforming catalyst at various reforming temperatures. The reaction characteristics of woody biomass tar were also investigated by TGA at a variety of heating rates. With all three catalysts conversion efficiency of tar and soot increased at increasing temperature. The reforming of tar and soot in the synthetic gas induce the increase of combustible gases such as $H_2$, CO and $CH_4$ in the product gas. The nickel-based catalyst showed a higher tar and soot conversion efficiency than mineral catalysts under the same temperature conditions.