• Korean Journal of Ecology and Environment
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• v.34 no.4 s.96
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• pp.261-266
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• 2001

Effects of elevated carbon dioxide ($CO_2$) on soil microbial processes were studied in a northern peatland. Intact peat cores with surface vegetation were collected from a northern Welsh fen, and incubated either under elevated carbon dioxide (700 ppm) or ambient carbon dioxide (350 ppm) conditions for 4 months. Higher algal biomass was found under the elevated $CO_2$ condition, suggesting $CO_2$ fertilization effect on primary production, At the end of the incubation, trace gas production and consumption were analyzed using chemical inhibitors. For methane ($CH_4$ ), methyl fluoride ($CH_3F$) was applied to determine methane oxidation rates, while acetylene ($C_2H_2$) blocking method were applied to determine nitrification and denitrification rates. First, we have adopted those methods to optimize the reaction conditions for the wetland samples. Secondly, the methods were applied to the samples incubated under two levels of $CO_2$. The results exhibited that elevated carbon dioxide increased both methane production (210 vs. $100\;ng\;CH_4 g^{-1}\;hr^{-1}$) and oxidation (128 vs. $15\;ng\;CH_4 g^{-1}\;hr^{-1}$), resulting in no net increase in methane flux. For nitrous oxide ($N_2O$) , elevated carbon dioxide enhanced nitrous oxide emission probably from activation of nitrification process rather than denitrification rates. All of these changes seemed to be substantially influenced by higher oxygen diffusion from enhanced algal productivity under elevated $CO_2$.

• Advances in Computational Design
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• v.4 no.4
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• pp.367-379
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• 2019

Multiple Inputs and Multiple Outputs (MIMO) Fuzzy logic model is developed to predict the engine performance and emission characteristics of pongamia pinnata biodiesel with hydrogen injection. Engine performance and emission characteristics such as brake thermal efficiency (BTE), brake specific energy consumption (BSEC), hydrocarbon (HC), carbon monoxide (CO), carbon dioxide ($CO_2$) and nitrous oxides ($NO_X$) were considered. Experimental investigations were carried out by using four stroke single cylinder constant speed compression ignition engine with the rated power of 5.2 kW at variable load conditions. The performance and emission characteristics are measured using an Exhaust gas analyzer, smoke meter, piezoelectric pressure transducer and crank angle encoder for different fuel blends (Diesel, B10, B20 and B30) and engine load conditions. Fuzzy logic model uses triangular and trapezoidal membership function because of its higher predictive accuracy to predict the engine performance and emission characteristics. Computational results clearly demonstrate that, the proposed fuzzy model has produced fewer deviations and has exhibited higher predictive accuracy with acceptable determination correlation coefficients of 0.99136 to 1 with experimental values. The developed fuzzy logic model has produced good correlation between the fuzzy predicted and experimental values. So it is found to be useful for predicting the engine performance and emission characteristics with limited number of available data.

• Membrane and Water Treatment
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• v.8 no.2
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• pp.171-184
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• 2017

This study presents the effect of hydraulic retention time (HRT) on the characteristics of emission of three major greenhouse gases (GHGs) including $CH_4$, $CO_2$ and $N_2O$ during operation of a sequencing batch reactor for aerobic oxidation of methane with denitrification (AeOM-D SBR). Dissolved $N_2O$ concentration increased, leveled-off and slightly decreased as the HRT increased from 0.25 to 1d. Concentration of the dissolved $N_2O$ was higher at the shorter HRT, which was highly associated with the lowered C/N ratio. A longer HRT resulted in a higher C/N ratio with a sufficient carbon source produced by methanotrophs via methane oxidation, which provided a favorable condition for reducing $N_2O$ formation. With a less formation of the dissolved $N_2O$, $N_2O$ emission rate was lower at a longer HRT condition due to the lower C/N ratio. Opposite to the $N_2O$ emission, emission rates of $CH_4$ and $CO_2$ were higher at a longer HRT. Longer HRT resulted in the greater total GHGs emission as $CO_2$ equivalent which was doubled when the HRT increased from 0.5d to 1.0 d. Contribution of $CH_4$ onto the total GHGs emission was most dominant accounting for 98 - 99% compared to that of $N_2O$ (< 2%).

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.1
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• pp.49-56
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• 1993

The net flux of global green house gases such as carbon dioxide($CO_2$), methane($CH_4$), and nitrous oxide($N_2O$) emitted from the rotation of paddy-upland soil during growing sesaon under different cropping system was determined. The results obtained were summarized as follows : 1. The net flux of $CO_2$ during the growing season was the highest from continuous cultivation of rice but the lowest from rotation cultivation of rice-soybean. Under the different cropping system the highst emission was from soil of continuous cultivation of rice, but the lowest from converted system. 2. The net emission of methane was the highest from the sold of continuous cultivation of rice, but the flux was remarkably decreased by differing the cropping system. 3. $N_2O$ was emitted greatly from the every two year rotation of potato-chinese cabbage and the next rank was from continuous cultivation of rice, but was decreased notably from rotation cultivation of rice-soybean and potato-chinese cabbage under rotation of paddy-upland cropping system. 4. The ratio of oxygen and carbon dioxide in the soil air was much different with glowing season, the ratio was varied with 4~10 percents for oxygen and 1~22 percents for carbon dioxide. The ratio of carbon dioxide was dozens or hundreds times to that of air, and the variation was very high also. 5. The emission of global green house gases such as carbon dioxide, methane and nitrous oxide was affected by the moisture, temperature and nutrients of soils and the growth period of crops.

• Korean Journal of Environmental Agriculture
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• v.36 no.2
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• pp.73-79
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• 2017

BACKGROUND: Carbonized biomass is a carbon-rich solid product obtained by the pyrolysis of biomass. It has been suggested to mitigate climate change through increased carbon storage and reduction of greenhouse gas emission. The objective of this study was to evaluate carbon dioxide ($CO_2$) and nitrous oxide ($N_2O$) emissions from soil after carbonized biomass addition. METHODS AND RESULTS: The carbonized biomass was made from a pyrolyzer, which a reactor was operated about $400{\sim}500^{\circ}C$ for 5 hours. The treatments were consisted of a control without input of carbonized biomass and two levels of carbonized biomass inputs as 6.06 Mg/ha for CB-1 and 12.12 Mg/ha for CB-2. Emissions of $CO_2$ and $N_2O$ from orchard soil were determined using closed chamber for 13 weeks at $25^{\circ}C$ of incubation temperature. It was shown that the cumulative $CO_2$ were $209.4g\;CO_2/m^2$ for CB-1, $206.4g\;CO_2/m^2$ for CB-2 and $214.5g\;CO_2/m^2$ for the control after experimental periods. The cumulative $CO_2$ emission was similar in carbonized biomass input treatment compared to the control. It was appeared that cumulative $N_2O$ emissions were $4,478mg\;N_2O/m^2$ for control, $3,227mg\;N_2O/m^2$ for CB-1 and$ 2,324mg\;N_2O/m^2$ for CB-2 at the end of experiment. Cumulative $N_2O$ emission contents significantly decreased with increasing the carbonized biomass input. CONCLUSION: Consequently the carbonized biomass from byproducts such as pear branch residue could suppress the soil $N_2O$ emission. The results fromthe study imply that carbonized biomass can be utilized to reduce greenhouse gas emission from the orchard field.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.531-537
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• 2009

Climate changes including environmental disasters after reckless industrialization have been globally witnessed. Considerable attention on the imminent need for developing CCS(Carbon dioxide Capture and Storage) methodologies to minimize the emission thus has been given. Chemical absorption is particularly regarded important because of its commercial availability and applicability to large scale plants. This paper addresses recent trends of chemical absorption technologies and the need for the further research on the topic from the perspective of process systems engineering(PSE).

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.3
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• pp.187-197
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• 2010

Carbon dioxide Capture and Storage(CCS) is regarded as one of the most promising options to response climate change. CCS is a three-stage process consisting of the capture of carbon dioxide($CO_2$), the transport of $CO_2$ to a storage location, and the long term isolation of $CO_2$ from the atmosphere for the purpose of carbon emission mitigation. Up to now, process design for this $CO_2$ marine geological storage has been carried out mainly on pure $CO_2$. Unfortunately the $CO_2$ mixture captured from the power plants and steel making plants contains many impurities such as $N_2$, $O_2$, Ar, $H_2O$, $SO_2$, $H_2S$. A small amount of impurities can change the thermodynamic properties and then significantly affect the compression, purification, transport and injection processes. In order to design a reliable $CO_2$ marine geological storage system, it is necessary to analyze the impact of these impurities on the whole CCS process at initial design stage. The purpose of the present paper is to compare and analyse the relevant physical property models including BWRS, PR, PRBM, RKS and SRK equations of state, and NRTL-RK model which are crucial numerical process simulation tools. To evaluate the predictive accuracy of the equation of the state for $CO_2-SO_2$ mixture, we compared numerical calculation results with reference experimental data. In addition, optimum binary parameter to consider the interaction of $CO_2$ and $SO_2$ molecules was suggested based on the mean absolute percent error. In conclusion, we suggest the most reliable physical property model with optimized binary parameter in designing the $CO_2-SO_2$ mixture marine geological storage process.

• Journal of the Korea Institute of Building Construction
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• v.10 no.3
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• pp.83-90
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• 2010

The carbon dioxide($CO_2$) emissions that result from construction are one of the main factors causing a global warming problem. It is therefore necessary to make efforts to reduce $CO_2$ emissions in the construction industry. Some researchers have studied $CO_2$ emissions in the industry ; however, there has been a lack of study on $CO_2$ emissions cost. Therefore, in this study, the construction costs, including the $CO_2$ emission cost, of masonry wall type, which is a common brick wall, concrete brick wall, and fired brick wall, were examined. The purpose of this study is to compare the construction costs of masonry wall types, including $CO_2$ emission costs. The study found that the $CO_2$ emission costs were highest for the fired brick wall, followed by the concrete brick wall. This research could provide basic information that can be used in other engineering methods to convert $CO_2$ emissions to $CO_2$ emission cost.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2006.11a
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• pp.328-333
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• 2006

A few methodologies have been recently developed to estimate the environmental affect when various materials and components are used in building life cycle. The direct survey method has limitations to analyze the environmental problems because of the limit of survey scope and cost. Therefore, another indirect method has been developed as alternatives. The indirect method is represented as input-output analysis. This paper aimed at analyzing the estimation the environmental affect of building materials and works at building construction, utilizing the input-output analysis as a indirect estimation method. The results suggested that the building works is overally responsible for the energy consumption and $CO_2$ emission. In other words, Over the 80% of the total consumption and $CO_2$ emission are resulted at the building work.

• Land and Housing Review
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• v.3 no.4
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• pp.399-406
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• 2012

One-third of total energy and 50% of $CO_2$ emissions arise from construction phase. Because of this global amount of energy consumption and $CO_2$ emission, we must do our best to solve this problem. But our existing ways of meeting this problem has focused on the energy consumption saving of the construction and dwelling stage. On the other hand, we has been treated too lightly for handling the $CO_2$ emissions problem during the maintenance management and the demolition process so far,. In this paper, we quantitatively predicted and evaluated the environmental load in each construction step during all life cycle. And, we developed the environmental load assessment program for each construction step. And we proposed the reliable decision support model for objective and reliable environmental load assessment and reduction. This result must help the development of construction technology and low carbon & green growth.