• Advances in environmental research
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• v.3 no.2
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• pp.107-116
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• 2014

This study aimed to synthesize dispersed and reactive nanoscale zero-valent iron (nZVI) with poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA), nontoxic and biodegradable stabilizer. The nZVI used for the experiments was prepared by reduction of ferric solution in the presence of PVP/VA with specific weight ratios to iron contents. Colloidal stability was investigated based on the rate of sedimentation, hydrodynamic radius and zeta potential measurement. The characteristic time, which demonstrated dispersivity of particles resisting aggregation, increased from 21.2 min (bare nZVI) to 97.8 min with increasing amount of PVP/VA (the ratios of 2). For the most stable nZVI coated by PVP/VA, its reactivity was examined by nitrate reduction in a closed batch system. The pseudo-first-order kinetic rate constants for the nitrate reduction by the nanoparticles with PVP/VA ratios of 0 and 2 were 0.1633 and $0.1395min^{-1}$ respectively. A nitrogen mass balance, established by quantitative analysis of aqueous nitrogen species, showed that the addition of PVP/VA to nZVI can change the reduction capacity of the nanoparticles.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.5
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• pp.374-380
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• 2014

To estimate greenhouse gas (GHG) emission, the inventory of rice cultivation at the farming without agricultural chemicals was established from farmers in Gunsan, Jeonbuk province in 2011~2012. The objectives of this study were to calculate carbon footprint and analyse the major factor of GHGs. To do this, we carried out a sensitivity analysis using the analyzed main factors of GHGs and estimated the mitigation potential of GHGs. Also we suggested agricultural methods to reduce GHGs that can be appled by farmers at this region. At the farming system without agricultural chemicals, carbon footprint of rice production unit of 1 kg was 2.15 kg $CO_2.-eq.kg^{-1}$. Although the amount of carbon dioxide ($CO_2$) emission was the largest among GHGs, methane ($CH_4$) emission had the highest contribution to carbon footprint on rice production system when it was converted to carbon dioxide equivalent ($CO_2-eq.$) multiplied by the global warming potential (GWP). Main source of $CO_2$ emission in the rice farming system without agricultural chemicals was combustion of fossil fuels used by agricultural machinery. Most of the $CH_4$ was emitted during rice cultivation practice and its major emission factor was flooded paddy field in anaerobic condition. Also, most of the $N_2O$ was emitted from rice cultivation process. Major sources of the $N_2O$ emission was application of fertilizer such as compound fertilizer. As a result of sensitivity analysis in energy consumption, diesel had the highest sensitivity among the energy inputs. With the reduction of diesel consumption by 10%, it was estimated that $CO_2$ potential reduction was about 2.0%. With reducing application rate of compound fertilizer by 10%, the potential reduction was calculated that $CO_2$ and $N_2O$ could be reduced by 0.5% and 0.9%, respectively. At the condition of 10% reduction of silicate and compost, $CO_2$ and $CH_4$ could be reduced by 1.5% and 1.6%, respectively. With 8 days more drainage than the ordinary practice, $CH_4$ emission could be reduced by about 4.5%. Drainage and diesel consumption were the main sources having the largest effect on the GHG reduction at the farming system without agricultural chemicals. Based on the above results, we suggest that no-tillage and midsummer drainage could be a method to decrease GHG emissions from rice production system.

• Korean Journal of Materials Research
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• v.29 no.10
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• pp.592-602
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• 2019

Feasibility is investigated for reduction of chromium ore by Si sludge with mixed silicothermic and carbothermic reaction. The reduction behavior of chromium ore using Si sludge is investigated precisely to determine the effects of carbon addition, reaction time, and reaction temperature. The pellets are dropped into the furnace after temperature stabilized. As the amount of C addition increases, the amounts of CO and $CO_2$ gas generation increase. After the dropping of the pellets, the pellets are heated and the reaction starts at about 1,573 K or higher. The pellets maintain their shape until 10 min after the drop, and then melted. As the holding time increased, the size of the reduced metal particles increased. The chromium ore is rapidly reduced by the Si sludge, and the slag penetrated into the chromium ore and reduction progressed inside. As the reduction temperature increased, the reaction initiation time is shortened and the reaction fraction of the reduction reaction increased. As the reaction temperature increased, agglomeration of reduced ferrochrome metal is promoted.

• Clean Technology
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• v.17 no.4
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• pp.406-411
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• 2011

A detailed database of waste heat is built to propose energy exchange networks to recover waste energy in Pohang Steel Industrial Complex. A visualized technique is used to figure out the status of waste heat energy and to suggest potential energy exchange networks. Several energy networks are proposed in terms of temperature level, the amount of available energy, distance, and construction cost. A simple economical assessment is applied to the energy exchange networks which have higher economic potential. Their average payback period is estimated to be 2.8 years. The total amount of energy saving by constructing the proposed energy exchange networks is 4,778 TOE per year. It corresponds to 11,160 ton $CO_2$ reduction with the assumption that the recycled waste energy replaces the use of LNG in energy-demanding companies.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.3
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• pp.89-96
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• 2013

Now-a-days, a manhole adopted since the late 1990s and produced using the polymer concrete has widely used due to the various benefits. While entering the High oil prices times, however, and with the price increase of the petrochemical materials, the cost of manufacture of polymer concrete was elevated and the resulting polymer concrete's weakness is being put on. Accordingly, the development of economic cement concrete manholes, which can replace the outstanding bending strength of manhole made of high-price polymer concrete, has been required. In this study, based on the cement technology of fast hardening armorphous calcium aluminate (ACA), by minimizing the amount of cement using the industrial byproducts, to develop the eco-friendly high-toughness concrete manhole, which can reduce $CO_2$ reduction, was intended. As the results, the cement concrete manhole, which economic, eco-friend, and meeting the performance requirements, was developed.

• Journal of the Korean Solar Energy Society
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• v.30 no.6
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• pp.34-43
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• 2010

Recently environmental regulations like the Kyoto Protocol, adopted in 1997, required the reduction of the greenhouse gas of 5.2% up to 1990 regulations. and 13th General Assembly in 2007, held in Bali of India, have agreed to duty reduction even in developing countries in 2013. Because of the lack of information about real process in small or middle size industries, most recent research omitted to calculate green house gas emissions from the industrial process. Bottom-up methodology will be applied for calculation of green house gasemission from industry sector to solve these problems in this research. Total amount from industry sector of Shicheung-City in 2007 was about 1,797,305 tons of greenhouse gas $CO_2$ and 3,049,403 tons of the greenhouse gas $CO_2$ calculated from industry sector of Ansan-City in 2007.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.1
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• pp.25-33
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• 1998

We have studied the reduction of NO by propane over perovskite-type oxides prepared by malic acid method. The catalysts were modified to enhance the activity by substitution by substitution of metal into A or B site of perovskite oxides. In addition, the reaction conditions, such as temperature, $O_2$ concentration, space velocity have been studed. In the $LaCoO_3$ type catalyst, the partial substitution of Ba, Sr into A site enhanced the catalytic activity in the reduction of NO. In the $La_{0.6}Sr_{0.4}Co_{1-x}Fe_xO_3(x=0 \sim 1.9)$ catalyst, the partial substitution of Fe into B site enhanced the conversion of NO, but excess amount of Fe decreased the conversion of NO. The surface area and catalytic activity of perovskite catalysts prepared by malic acid method showed higher values than those of solid reaction method. In the $La_{0.6}Sr_{0.4}Co_{1-x}Fe_xO_3$ catalyst, the conversion of NO increased with increasing $O_2$ concentration and contact time. The introduction of water into reactant feed decreased the catalytic activity.

• Journal of Climate Change Research
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• v.5 no.2
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• pp.153-163
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• 2014

This study analyzed directions of the energy product efficiency improvement and Carbon Tax for the domestic building sector. In order to analyze GHG reduction potential and total cost, the cost optimization model MESSAGE was used. In the case of the "efficiency improvement scenario," the cumulative potential GHG reduction amount - with respect to the "Reference scenario" - from 2010 to 2030 is forecast to be $104MtCO_2eq$, with a total projected cost of 2.706 trillion KRW. In the "carbon tax scenario," a reduction effect of $74MtCO_2eq$ in cumulative potential GHG reduction occurred, with a total projected cost of 2.776 trillion KRW. The range of per-ton GHG reduction cost for each scenario was seen to be approximately $-475{\sim}272won/tCO_2eq$, and the "efficiency improvement scenario" showed as the highest in the order of priority, in terms of the GHG reduction policy direction. Regarding policies to reduce GHG emissions in the building sector, the energy efficiency improvement is deemed to deployed first in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.378-384
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• 2019

In the food wastewater treatment facilities, the water quality improvement effect and the greenhouse gas emission amount followed by the change in electricity usage through a change of the aeration tank ventilation system were evaluated. also, the amount of greenhouse gas emission followed by the change in electricity usage through the change of the sludge dewatering, storage, transporting method was also evaluated. The total GHG emission from food wastewater treatment facility improvement were divided into direct emissions from the treatment processes and indirect ones from electricity usage. The water quality improvement effect of wastewater treatment plant was found to be 63.3% for BOD removal rate, 42.0% for COD removal rate, 71.0% for SS removal rate and 39.6% for T-N removal rate. and according to the results of calculating output by applying both direct emissions of greenhouse gas (Scope 1) and the indirect emission (Scope 2) of greenhouse gas followed by changes in power consumption. It was estimated that there was a total of 276.0tCO2eq./yr(7.5%) greenhouse gas reduction effect from 3,668.8tCO2eq./yr before improvement to 3,392.8tCO2eq./yr after improvement. In this result is not due to the effects of water quality improvement of emission source, but because the reduction in electricity use has reduced the amount of greenhouse gas emissions.

• Clean Technology
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• v.20 no.4
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• pp.439-448
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• 2014

The potential mitigation of greenhouse gas (GHG) is studied in the Pohang steel industrial complex (PHSIC). The total GHG emission in 2010 is estimated to be in the range from 4,174,000 to 4,574,000 $tCO_2-eq$ in PHSIC. To meet the target proposed by the government, it is needed to reduce 552,000 $tCO_2-eq$ at minium by 2020. To estimate the potential amount of GHG reduction, the technologies used in the voluntary carbon reduction projects are applied to 51 companies which are subject to GHG target management. From the viewpoint of technological availability and payback period, the fuel conversion and waste heat recovery have an advantage in the short term with a possibility to reduce 160,000 $tCO_2-eq$. In the mid term, the thermal technologies in steel and iron industry have the potential to cut 229,000 $tCO_2-eq$, while the electrical technologies have the potential of 125,000 $tCO_2-eq$ reduction. The gap between the target GHG mitigation and potential reduction using the short and mid term technologies is about 38,000 $tCO_2-eq$, which should be compensated by the fundamental process innovation and the implementation of the most cutting-edge technologies including renewable energy.