• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1243-1252
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• 2019

The purpose of this study is to investigate the optimum conditions of biomass pretreatment with potassium hydroxide (KOH) for efficient utilization of cellulose, hemicellulose and lignin from Miscanthus. The optimization of variables was performed by response surface methodology (RSM). The variation ranges of the parameters for the RSM were potassium hydroxide 0.2~0.8 M, reaction temperature 110~190℃ and reaction time 10~90 min. The optimum conditions of alkali pretreatment from Miscanthus were determined as follows: concentration of KOH 0.47 M, reaction temperature 134℃ and reaction time 65 min. At the optimum conditions, the yield of cellulose from the solid fraction after pretreatment was predicted to be 95% by model prediction. Finally, 66.1 ± 1.1% of cellulose were obtained by verification experiment under the optimum conditions. The order contents of solid extraction were hemicellulose 26.4 ± 0.4%, lignin 3.7 ± 0.1% and ash 0.5 ± 0.04%. The yield of ethanol concentration of 96% was obtained using separated saccharification and fermentation.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.3
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• pp.89-99
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• 2019

The project to utilize kenaf as thermal power plant fuel has a positive effect on the unused energy utilization, greenhouse gas reduction, and farm income. However, it is analyzed that it is difficult to secure economical efficiency because the fuel cost of kenaf is higher than that of power by thermal power plant and Renewable Energy Certification (REC). The project of power generation using kenaf is meet the government's major policies, while government support is essential for securing economical efficiency. As a result of the sensitivity analysis on the ratio of the government subsidies, to secure economical efficiency, the power generation prices using kenaf through the direct financial support of the government indicate that 47% and 76% of kenaf fuel cost are supported by government in case of the Saemangeum reclamation and Gangneung-si, respectively. In the case of the government indirect policy support, if kenaf is included as a renewable energy source of Renewable Energy Portfolio Standard and REC is granted, the economic efficiency of Saemangeum reclamation and Gangneung-si is obtained when REC secured at 1.05 or more and 2.43 or more, respectively. The results of this study are meaningful in that the direct and indirect effects of the government on the development of the herbaceous energy crop, kenaf, were evaluated economically. These results are to suggest the need for demonstration study, but economics analyze and evaluate are necessary based on operational data through the demonstration phase in the future.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.3
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• pp.324-330
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• 2013

One of the abundant biomass for bioenergy production is thought to be agricultural by-products produced annually. The purpose of this study were to provide basic information about the changes of the moisture contents and chemical compositions for storage periods and bale types of rice straw, and it was attempted for the first time. The bale types of rice straw which were harvest in October 2011, were the square bale, the round bale, and the wrapped round bale type with plastic, respectively. Each of bale were stored in house, outdoor, and rain sheltering facilities condition for 1 year. The moisture contents and chemical compositions for each bale type are investigated for the 3-storage stages (0, 6, 12 month). While the moisture contents of the square and round bales stored in house condition were ranged from 20~25%, the square bale stored under the rain shelter facilities was showed the lowest moisture content less than 20% during the storage periods. For the chemical compositions, the cellulose and hemicellulose contents of rice straw bale stored in outdoor condition were decreased with the storage periods. However, in house condition, the chemical compositions of the square and round bales were slightly increased at the middle and the end of storage stages (6 and 12 months) compared with the initial storage stage (0 month). In conclusion, while optimum and favorable storage conditions of agricultural by-products is a house storage of the bale with plastic, if the bale can stored at outdoor, water penetration prevention such as the rain shelter facilities is required.

• Journal of the Korean Wood Science and Technology
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• v.43 no.3
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• pp.355-363
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• 2015

Asian lignin was efficiently depolymerized with supercritical ethanol and Ru/C catalyst at various reaction temperature (250, 300, and $350^{\circ}C$). Lignin-oil was subjected to several physicochemical analyses such as GC/MS, GPC, and elemental analysis. With increasing reaction temperature, the yield of lignin-oil decreased from 89.5 wt% to 32.1 wt%. The average molecular weight (Mw) and polydispersity index (Mw/Mn) of lignin-oil obtained from $350^{\circ}C$ (547Da, 1.49) dramatically decreased compare to those of original asian lignin (3698Da, 2.68). This is a clear evidence of lignin depolymerization. GC/MS analysis revealed that the yield of monomeric phenols involving guaiacol, 4-ethyl-phenol, 4-methylguaiacol, syringol, and 4-methysyringol increased with increasing reaction temperature, and these were mostly produced with applying hydrogen gas and Ru/C catalyst (76.1 mg/g of lignin). Meanwhile, the carbon content of lignin-oil increased whereas the oxygen content decreased with increasing reaction temperature, suggesting that hydrodeoxygenation was significantly enhanced at higher temperature.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.52-52
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• 2018

목초지에서 비점오염원 유출특성은 가축밀도(stocking rate)와 방목형태(grazing management practice)에 기인하여 다르게 나타난다. 전통적인 방목형태는 한 대상지역에서 높은 가축밀도의 연속적인 방목(continuous grazing)을 취하는 것인데, 이 경우 토양압밀에 따른 강우의 침투량 감소, 가축의 배설물 축적 등으로 비점오염 유출량이 증가할 수 있으며, 식물의 재성장기간 부족으로 지속적인 방목지 운영이 어려울 수 있다. 순환방목(rotational grazing)은 이러한 연속적 방목 형태의 부정적인 영향을 개선하고자 대안으로 제시되었다. 방법은 구역을 나누고 초본식물의 생육상태를 고려하여 일정기간이 지나면 다른 구역으로 이동 시키며 방목하는 형태이다. 기존의 연구들은 단위 면적당 적정 가축밀도, 필드규모에서 방목형태에 따른 비점오염 유출특성에 초점을 두고 있으며, 결과들은 가축밀도의 영향보다는 방목형태에 의한 수문, 수질 영향이 더 크다고 지적하고 있다. 이에 본 연구에서는 이러한 가축밀도(Heavy vs Light) 및 방목형태(Continuous vs Rotational)가 유역의 비점오염 유출특성에 미치는 영향을 정량적으로 평가하고자, 미국 북텍사스 지역에 위치한 Clear Creek 유역을 대상으로 4개의 방목시나리오(heavy continuous[HC], light continuous[LC], multi-paddock[MP], no grazing)를 구성하고 Soil and Water Assessment Tool(SWAT) 모형에 적용하였다. SWAT 모형은 대상유역 내 4개의 방목지에서 측정한 토양수분 및 식물 바이오매스 자료, 유역 출구점에서 관측된 장기간의 수문 수질 자료를 이용하여 검증되었다. 연구결과는 순환방목(MP) 시나리오가 수질보호 및 토양침식 방지, 식생의 영양염류 흡수능력이 커지는 것과 같이 생태계서비스 기능의 개선 측면에서 최적의 방목형태(best grazing management)인 것으로 나타났으며, 이러한 결과는 가축밀도 보다는 방목형태에 기인한 것으로 필드와 유역스케일에서 동일한 결과를 보여주었다. 그러나 유역 내 목초지의 차지비율에 따라 순환방목 채택에 따른 비점오염 유출량의 감소효과는 다르게 나타나게 된다.

• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.257-263
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• 2016

Objective of this study was to evaluate the carbon budget on 40 years old pear orchard at Naju. For carbon budget assessment, we measured the soil respiration, net ecosystem productivity of herbs, pear biomass and net ecosystem exchange. In 2015, pear orchard released about $25.6ton\;CO_2\;ha^{-1}$ by soil respiration. And $27.9ton\;CO_2\;ha^{-1}$ was sequestrated by biomass growth. Also about $12.6ton\;CO_2\;ha^{-1}$ was stored at pruning branches and about $5.2ton\;CO_2\;ha^{-1}$ for photosynthesis of herbs. As a result, 25.6 ton of $CO_2$ per ha is annually released to atmosphere. At the same time about 45.7 ton of $CO_2$ was sequestrated from atmosphere. When it sum up the amount of $CO_2$ release and sequestration, approximately $20.1ton\;CO_2\;ha^{-1}$ was sequestrated by pear orchard in 2015, and it showed no significant differences with net ecosystem exchanges ($17.8ton\;CO_2\;ha^{-1}\;yr^{-1}$) by eddy covariance method with the same period. Continuous research using various techniques will help the understanding of $CO_2$ dynamics in agroecosystem and it can be able to present a new methodology for assessment of carbon budget in woody crop field. Futhermore, it is expected that the this study can be used as the basic data to be recognized as a carbon sink.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.4
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• pp.13-28
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• 2023

This study assessed the biochemical methane potential (B_u-P) of three grass species-Poa pratensis (PP), Zoysia japonica (ZJ), and Agrostis stolonifera (AS). B_u-P values were determined as 0.330 Nm³/kg-VS_added for PP, 0.297 Nm³/kg-VS_added for ZJ, and 0.261 Nm³/kg-VS_added for AS. Notably, PP exhibited superior suitability for methane production. The investigation also examined the impact of silage storage duration on PP grass clippings, revealing a 19% decline in B_u-P from an initial value of 0.269 Nm³/kg-VS_added on day 0 to 0.217 Nm³/kg-VS_added on day 180. Throughout the storage period, there were significant increases in neutral detergent fiber (NDF), acid detergent fiber (ADF), and crude protein (CP) contents, rising from 67.59%, 39.68%, and 3.02% on day 0 to 77.12%, 54.65%, and 6.24% on day 180, respectively. These findings highlight the influence of storage duration on the anaerobic digestibility of PP grass clippings. To effectively utilize grass clippings as a renewable resource for methane production, further studies considering factors such as initial moisture content, pretreatment methods, and potential effects of residual pesticides are necessary to optimize anaerobic digestion efficiency for herbaceous biomass.