• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.407-414
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• 1999

We have studied the reduction of NO by CO over perovskite-type oxides prepared by malic and method. The catalysts were modified to enhance the activity by substitution of metal into A or B site of perovskite oxides. In the $LaCoO_3$ type catalyst, the partial substitution of Sr into A site enhanced the catalytic activity on the conversion of NO at less than $350^{\circ}C$. In the $La_{0.6}Sr_{0.4}Co_{1-x}Fe_xO_3$ catalyst, the partial substitution of Fe or Mn into B site enhanced the conversion of NO, but excess amount of Fe decreased the conversion of NO. In addition, $La_{0.6}Sr_{0.4}Co_{0.8}Fe_{0.2}O_3$ mixed with $SnO_2$ or $MnO_2$ showed the synergy effect on the reduction of NO. The introduction of water into reactants feed decreased the catalytic activity but the deactivation was shown to be reversible. The introduction of $SO_2$ into reactants feed also decreased the catalytic activity.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1343-1347
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• 2009

In order to comply with the global energy crisis and environment problem, it is necessary to research and develop the energy utilization technology with the reduction of the primary energy usage. Although the increasing rate of energy consumption started to attenuate, the entire consumption of energy as well as $CO_2$ emission rate tends to increase steadily along with an economic growth in Korea. The energy demand in Korea increases by annual 3.7% during the period from 2000 to 2006. And it is expected that we should take a charge of the greenhouse gas reduction obligation by the Climatic Change Convention(Kyoto Protocol) during the 2nd pledge period($2013{\sim}2017$). According to the IEA report in 2005, the emission amount of carbon dioxide is the 10th place in the world, and the increasing rate is 4.7% annually. Considering the economic scale of Korea, the degradation of energy usage is inevitable when the greenhouse gas reduction obligation come into effect. Therefore, effective energy usage is a very important issue to minimize baneful influence on industrial and economic activities.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.2
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• pp.137-143
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• 2004

For hydrogen generation from aqueous alkilne $NaBH_4$ solution, Co-B catalyst was prepared by chemical reduction method using $NaBH_4$ as a reduction chemical. Effects of solution temperature, amount of catalyst loading, $NaBH_4$ concentration, and NaOH (a base-stabilizer) concentration on the hydrogen generation rate were exmanined. Compared to Ru catalyst generally used, the low-cost Co-B catalyst exhibited almost comparable activity to the hydrogen generation reaction.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.3
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• pp.261-268
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• 2018

Sludge transporting pipes in wastewater treatment plant are easy to be clogged with struvite when the digested sludge and dehydrated filtrate are transported through the pipes, which lowers the efficiency of sludge treatment system in a WWTP. pH is one of the most important factors in struvite formation, and carbon dioxide separated from biogas can be used to control pH and struvite formation. By controlling pH, the amount of dehydrating agent can be reduced by about 10%, which saves the budget for facility maintenance. As $CO_2$ is reused and dehydrating chemicals are saved, the approach can contribute to global warming gas reduction.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.5
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• pp.13-18
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• 2012

This research is about the exhaust gas and driving performance test which are for CNG-Diesel dual fuel engine. The CNG-Diesel dual fuel engine converted from 2500cc diesel has two steps of injection systems; small amount of diesel is injected to mixture CNG in cylinder to ignite before CNG is injected into each intake manifold to form mixture. The amounts of output power and emission in duel fuel consumption were measured by engine dynamometer and exhaust gas analyzer. Over 90% of diesel consumption reduction, similar driving performance to current diesel engine and reduced emission on $CO_2$ and PM, respectively, were indicated through the measurements. The two steps of system were applied to vehicle to investigate exhaust gas characteristics and driving performance via NEDC mode and real driving test. Additional oxidation catalyst was applied to reduce emission on the test vehicle and the NEDC mode test showed the reduction of Co, $CO_2$, Pm and THC.

• Convergence Security Journal
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• v.13 no.3
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• pp.39-46
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• 2013

Recently, the problem of global warming has become a globally important issues. and To solve these problems, has been receiving increasing attention for the Green IT. In these situation, IT techniques are evolving with variety services and hacking techniques. so, it is inevitable to the use of a many and diverse secure system. As a result, Carbon Dioxide emissions are expected to increase. Therefore, in this paper is analyzed the factors of security system's $CO_2$ emissions through Experiments and A case study. and is proved that is reducing $CO_2$ emissions by improving the functional restructuring of the security system. In a future, this paper is expected to serve as a valuable Information for security network design and performance improvements and to reduce Carbon Emissions in the Field of IT.

• Nuclear Engineering and Technology
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• v.50 no.6
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• pp.886-889
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• 2018

This article presented two-staged chemical precipitation for radioactive wastewater decontamination by using chemical agents. The total amount of radioactive wastewater was $35m^3$, and main radionuclides were Cs-137, Cs-134, and Co-60. Initial radioactivity concentration of the liquid waste was 2264, 17, and 9 Bq/L for Cs-137, Cs-134 and Co-60, respectively. Potassium ferrocyanide, nickel nitrate, and ferrum nitrate were selected as chemical agents at high pH levels 8-10 according to the laboratory jar tests. After the process, radioactivity was precipitated as sludge at the bottom of the tank and decontaminated clean liquid was evaluated depending on discharge limits. By this precipitation method decontamination factors were determined as 66.5, 8.6, and 9 for Cs-137, Cs-134, and Co-60, respectively. By using the potassium ferrocyanide, about 98% of the Cs-137 was removed at pH 9. At the bottom of the tank, radioactive sludge amount from both stages was totally $0.98m^3$. It was transferred by sludge pumps to cementation unit for solidification. By chemical processing, 97.2% of volume reduction was achieved. The potassium ferrocyanide in two-staged precipitation method could be used successfully in large-scale applications for removal of Cs-137, Cs-134, and Co-60.

• Journal of the Korea Concrete Institute
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• v.29 no.4
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• pp.379-387
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• 2017

The objective of this study is to develop sustainable PVA fiber-reinforced cementitious composites (FRCCs) that could exhibit comparable strength level to normal PVA FRCCs with no recycled materials. To evaluate mechanical properties of the FRCCs, compressive, flexural and direct tensile tests were conducted. In addition to the test, to calculate amount of carbon dioxide ($CO_2$) emission at the stage of manufacturing the FRCCs, life cycle inventory data base (LCI DB) were referenced from domestic and Japan. From the test results, the mechanical properties such as compressive, flexural and direct tensile strengths were decreased as the replacement ratio of recycled materials increased. And it was determined that the amount of $CO_2$ emission was reduced for the specimens with higher water-binder ratio (W/B) and replacement ratios. It was also found that binder intensity ($B_i$) value was higher as replacement ratio of fly ash (FA) increased. This result means that larger amount of FA is need to deliver one unit of a given performance indicator (1 MPa of strength) of FRCCs compared to that of ordinary portland cement (OPC). As a result, it could be concluded that FRCCs with W/B 45% replaced by FA 25% and recycled sand (RS) 25% is desirable for both target performance and $CO_2$ emission.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.4
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• pp.143-152
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• 2020

This study analyzes in detail greenhouse gas emissions in building sector. To this end, this study used data on building characteristics (including building type, region, and construction year) and monthly energy consumptions (including electricity, city gas, and district heat) for all buildings from 2015 to 2018. These data were collected from the National Building Energy Database and the energy consumptions were converted into greenhouse gas (GHG) emissions. The total amount of GHG emissions from the building sector has increased steadily from 2015 (118.1MtCO2eq.) to 2018 (132.6MtCO2eq.). On the other hand, the more recently constructed buildings had lower GHG intensities. This result shows that strengthening building design criteria was effective on the reduction of GHG emissions in buildings, and that the increased buildings contributed to increasing GHG emissions of the building sector. In addition, sales facilities are thought to have the largest reduction potential as they had the highest amount of GHG emissions and GHG intensity. This study is expected to help establish new policies for GHG reduction in building sector as well as to evaluate the effects of existing policies.

• Resources Recycling
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• v.10 no.6
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• pp.9-14
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• 2001

A sulfuric acid leaching of $LiCoO_2$as cathodic active materials of lithium ion secondary batteries was investigated in terms of reaction variables. In the absence of a reducing agent, the extraction of cobalt was less than 40% in 2 M sulfuric acid at $75^{\circ}C$ instead of that of lithium could be almost 100% in the same conditions. To improve the Co extraction, hydrogen peroxide was used as a reducing agent in the range 2~20 vol%. When over 10vo1% hydrogen peroxide was added, the extractions of both metals were improved to about 95%. It seems to be due to the reduction of Co(III) to Co(II) that can be readily dissolved. The extractions of Co and Li were increased with increasing $H_2$$SO_4$concentration and temperature, and amount of hydrogen peroxide and with decreasing of pulp density. The optimum leaching conditions were determined at $2 M H_2$$SO_4$concentration, $75^{\circ}C$ operating temperature, 100 g/L. initial pulp density, 20 vol% $H_2$$O_2$addition and 30 min.