• 전기학회논문지
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• 제67권10호
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• pp.1278-1285
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• 2018

For saving electricity bill, energy storage system(ESS) is being installed in factories, public building and commercial building with a Time-of-Use(TOU) tariff which consists of demand charge(KRW/kW) and energy charge(KRW/kWh). However, both of peak reduction and ESS special tariff are not considered in an analysis of initial cost payback period(ICPP) on ESS. Since it is difficult to reflect base rate by an amount of uncertain peak demand reduction during mid-peak and on-peak periods in the future days. Therefore, the ICPP on ESS can be increased. Based on this background, this paper presents the advanced analysis method for the ICPP on ESS. In the proposed algorithm, the representative days of monthly electricity consumption pattern for the amount of peak reduction can be found by the k­means clustering algorithm. Moreover, the total expected energy costs of representative days are minimized by optimal daily ESS operation considering both peak reduction and the special tariff through a mixed-integer linear programming(MILP). And then, the amount of peak reduction becomes a value that the sum of the expected energy costs for 12 months is maximum. The annual benefit cost is decided by the amount of annual peak reduction. Two simulation cases are considered in this study, which one only considers the special tariff and another considers both of the special tariff and amount of peak reduction. The ICPP in the proposed method is shortened by 18 months compared to the conventional method.

• 한국지열·수열에너지학회논문집
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• 제19권4호
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• pp.18-26
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• 2023

Green-remodeling is to improve the energy performance of existing buildings that have been aged for more than 15 years since completion. In order to achieve the national greenhouse gas emission reduction plan in the building sector, it is necessary to analyze the carbon reduction effect by considering the internal carbon emissions that may occur during green-remodeling of old buildings. This study analyzed the effects of energy reduction and carbon emission reduction when green-remodeling was applied to old health centers constructed in 1992. When applying green-remodeling, the carbon emission reduction effect considered the embodied carbon emission of the improvement items and the carbon emission at the building operation stage. When applying green-remodeling to existing buildings, energy consumption was reduced by 39.3%, and carbon emissions were reduced by 48.9% after 27 years of green-remodeling. In order to reduce carbon emissions, it was important to apply a renewable system as an item to improve the performance of green-remodeling. In particular, it was confirmed that it is very important to consider the photovoltaic system as a top priority for the carbon emission reduction.

• Earthquakes and Structures
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• 제23권2호
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• pp.139-150
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• 2022

In most self-center braces, decreasing residual deformation is possible only by increasing pretension force, which results in lower energy dissipation capacity. On the other hand, increasing energy dissipation capacity means higher values of residual deformation. The goal of this research was to find the best design for a self-centering buckling restrained brace (SC-BRB) system by balancing self-centering capability and energy dissipation. Three, six, and nine-story structures were investigated using OpenSees software and the TCL programming language to achieve this goal. For each height, 62 different SC-BRBs were considered using different values for the pretension force of cables, the area of the buckling restrained brace (BRB) core plate, and the yield stress of the core plate. The residual deformation and dissipated energy of all the models were calculated using nonlinear analyses after cyclic loading was applied. The optimum design for each height was determined among all the models and was compared to the structure equipped with the usual BRB. The residual deformation of the framed buildings was significantly reduced, according to the findings. Also the reduction of the energy dissipation was acceptable. The optimum design of SC-BRB in 6-story building has the most reduction percent in residual deformation, it can reduce residual deformation of building 83% while causing only a 57% of reduction in dissipated energy. The greatest reduction in residual deformation versus dissipated energy reduction was for the optimum SC-BRB design of 9-story building, results indicated that it can reduce residual deformation of building 69% while causing only a 42% of reduction in dissipated energy.

• Carbon letters
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• 제1권1호
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• pp.17-21
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• 2000

Catalytic reduction and oxidation of NO over polyacrylonitrile based activated carbon fibers (PAN-ACF) under various conditions were carried out to develop removal process of NO from the flue gas. The effect of temperature, oxygen concentration and the moisture content for the reduction of NO with ammonia as a reducing agent was investigated. The reduction of NO increased with the oxygen concentration, but decreased with the increased temperature. The moisture content in the flue gas affects the reduction of NO as the inhibition of the adsorption of the other components and the reaction on the surface of ACE For the oxidation of NO to $NO_2$ over PAN-ACF without using a reducing gas, it showed the temperature and the oxygen concentration of the flue gas are the important factors for the NO conversion in which the conversion increased with oxygen concentration and decreased with the temperature increase and might be the alternative option for the selective catalytic reduction process.

• 한국기후변화학회지
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• 제7권3호
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• pp.231-236
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• 2016

Electrocatalytic reduction can produce useful chemicals and fuels such as carbon monoxide, methane, formate, aldehydes, and alcohols using carbon dioxide, the green house gas, as a reactant through the supply of electrical energy. In this study, tin-lead (Sn-Pb) alloy electrodes are fabricated by electrodeposition on a carbon paper with different alloy composition and used as cathode for electrocatalytic reduction of carbon dioxide into formate in an aqueous system. The prepared electrodes are measured by Faradaic efficiency and partial current density for formate production. Electrocatalytic reduction experiments are carried out at -1.8 V (vs. Ag/AgCl) using H-type cell under ambient temperature and pressure and the gas and liquid products are analyzed by gas chromatograph and liquid chromatograph, respectively. As results, the Sn-Pb electrodes show higher Faradaic efficiency and partial current density than the single metal electrode. The Sn-Pb alloy electrode which have Sn:Pb molar ratio=2:1, shows the highest Faradaic efficiency of 88.7%.

• 한국수소및신에너지학회논문집
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• 제17권3호
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• pp.248-254
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• 2006

The promotion effects of noble metals upon the activity and reducibility in steam methane reforming over $Ni/MgAl_2O_4$ catalysts were investigated. While $Ni/MgAl_2O_4$ catalysts require the pre-reduction by $H_2$, the noble metal-added catalysts show high catalytic activities without pre-treatment. According to $CH_4$-TPR, the addition of noble metal makes the $Ni/MgAl_2O_4$ catalyst easily reducible. The reduction degree of NiO in the noble metal-added catalysts after using at $650^{\circ}C$ without pre-reduction was $15{\sim}20%$, and was lower than that in the $H_2$-reduced $Ni/MgAl_2O_4$ catalyst(reduction degree=27%). The enhancement of the catalytic activity over noble metal-added catalysts results from easier reducibility by addition of noble metal and the synergy effect between noble metal and Ni.

• 한국수소및신에너지학회논문집
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• 제15권3호
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• pp.201-207
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• 2004

Redox characteristics of metal oxide for hydrogen production by thermochemical water-splitting were investigated. $CuFe_2O_4$ as a redox pair that had a different molar ratio of Cu and Fe were prepared by co-precipitation method. Hydrogen production consisted of water-splitting step and thermal reduction step was performed below 1200K. Redox characteristics of Cu-ferrites were studied using the thermal gravimetric analysis technique. Also, structure change of Cu-ferrite during thermal reduction was investigated using the high temperature controlled XRD. In results, oxygen release of Cu-ferrite during the thermal reduction was initiated at oxygen site combined with Cu. Consequently, oxygen release amount of Cu-ferrite was increased with increase of Cu molar ratio of Cu-ferrite. It was found that thermal reduction of Cu-ferrite was begun at $875^\circ{C}$. It was confirmed that structure of Cu-ferrite was changed to metal and cation excess metal oxide during the thermal reduction step.

• 상하수도학회지
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• 제24권3호
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• pp.319-332
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• 2010

In general, wastewater treatment systems consume high-energy consumption depending on operation characteristics of the facilities. Therefore, greenhouse gas(GHG) reduction activities that are application of digestion gas, induction of renewable energy etc. are conducted to reduce energy consumption and to increase energy independence ratio. In this study, GHG reduction in wastewater treatment system identified, searched application of Clean Development mechanism(CDM) approved methodology. If the methodologies apply to GHG reduction activities such as application of digestion gas, heat pump system using the wastewater as heat source, hydropower using the methodology determined CDM applicability, otherwise through several assumptions calculated expectable GHG reduction emissions and determined CDM applicability. As a result, the order of calculated GHG reduction emission showed that collected and energy generation of digestion gas is 66,775 $tCO_2$/yr, gas engine cogeneration system is 8,182 $tCO_2$/yr, heat pump system using the wastewater as a heat source is 72,715 $tCO_2$/yr, and hydropower is 561 $tCO_2$/yr. Consequently, the order of calculated Certified Emission Reductions(CERs) benefit showed that heat pump system using the wastewater, as a heat source is 1,381 million won/yr was estimated as the highest, followed by a collected and energy generation of digestion gas is 1,268 million won/yr.

• 전기학회논문지
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• 제59권7호
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• pp.1232-1236
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• 2010

In this Paper, optimal capacity of energy storage and amount of $CO_2$ reduction in Jeju is calculated. Based on electricity demand data of Je-Ju from 2006 to 2007, the estimation electricity demand from 2009 to 2018 is performed. To calculate the amount of maximum $CO_2$ reduction and energy storage capacity in Jeju, the 4th power supply planning and IPCC guideline are used. Finally, Optimal capacity of energy storage and the amount of $CO_2$ reduction are showed.

• Nuclear Engineering and Technology
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• 제42권2호
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• pp.183-192
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• 2010

An electrochemical reduction of a mixture of metal oxides was conducted in a LiCl molten salt containing 3 wt% $Li_2O$ at $650^{\circ}C$. The oxide reduction was carried out by applying a current to an electrolysis cell, and the $Li_2O$ concentration was analyzed during each run. The concentration of $Li_2O$ in the electrolyte bulk phase gradually decreases according to Faraday's law due to a slow diffusion of the $O^{2-}$ ions. A hindrance effect of the unreduced metal oxides was observed for the reduction of the uranium oxide. Cs, Sr, and Ba of high heat-load fission products were diffused into and accumulated in the salt phase as predicted with thermodynamic consideration.