• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.14-23
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• 2018

The effect of dodecylbenzene sulfonic acid (DBSA) with different addition amount of DBSA ($M_{DBSA}$), temperatures and solvent-to-oil ratio (SOR, v/v) on asphaltene aggregation in a solvent deasphalting system was investigated. Increasing the $M_{DBSA}$ at SOR 10 and $55^{\circ}C$ caused the asphaltene removal ratio (ARR) to increase first, then maximize at 1 wt% of $M_{DBSA}$ and then decrease continuously. Based on the SARA (saturate, aromatic, resin, asphaltene) composition, the adsorption amount of DBSA on the asphaltene surface and the self-aggregation of the DBSA, the reason for the change in ARR with $M_{DBSA}$ was found due to the adsorption mechanism. In addition, the asphaltene-resin-DBSA colloidal size confirmed the change of adsorption behavior between the asphaltene and DBSA. Based on the results of this study, a hypothetical adsorption mechanism of DBSA on asphaltene aggregation in the solvent deasphalting system was conceived of and proposed.

• Solar Energy
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• v.9 no.3
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• pp.44-54
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• 1989

Heat transfer phenomena during inward melting process of the phase change material were studied experimentally. N-docosane paraffin [$C_{22}H_{46}$] is used for phase change material and its melting temperature is $42.5^{\circ}C$. Experiments were performed for melting of an initially no-sub cooled or subcooled solid in a horizontal cylinder, in order to compare and investigate the radial temperature distribution, ratio of melting and melted mass, various energy components stored from the cylinder wall, figure of the melting front in the horizontal cylinder. The solid-liquid interface motion during phase change was recorded photographically. The experimental results reaffirmed the dominant role played by the conduction at early stage, by the natural convection at longer time during inward melting in the horizontal cylinder. Ratio of melting and melted mass are more influenced by wall temperature, rather than by the initial temperature of solid. The latent energy is the largest contributor to the total stored energy.

• Journal of Climate Change Research
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• v.7 no.1
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• pp.59-68
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• 2016

The world's major countries have focused on the renewable energy industry as the solution to climate change and the energy crisis. Nevertheless, there are no studies on the economic effects of the renewable energy industry. This study analyzed the economic effects of Korea's renewable energy industry by using the 2010 Input-Output Table. It is estimated that Korea's renewable energy industry made a production-induced effect of 2.0262 won, and a value-added-induced effect of 0.6138 won through an increase in output growth of 1 won, and an employment-induced effect of 2.3046 labors through an increase in output growth of 1 billion won. Both the effect ratio and the response ratio were greater than 1, which means the renewable energy industry is an intermediate manufacturing industry whose forward linkage effect and backward linkage effects are large. These results show differences with previous studies that classified electricity sector and renewable energy industry into final primary production industries. It is expected that the economic effects of the renewable energy industry will become greater in the future. Therefore, research on statistics related to the renewable energy industry is needed for more precise analysis.

• KIEAE Journal
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• v.13 no.2
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• pp.21-26
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• 2013

Due to the increasing concerns about the buildings which have affected the global environment, most countries have enacted a regulation for the sustainability of domestic buildings. In 2008, the Korean government started to enact a regulation of apartment and office buildings for energy saving. Many research on the sustainable apartment building focuses on $84m^2$ or larger type in response to market demand; therefore, small size type such as $46m^2$ type needs to be researched. In addition, the research on the orientation and window to wall ratio of the building have been separately studied as a means of energy reduction; therefore, the research on correlation of the orientation and window to wall ratio hasn't been fully explored yet. This paper analyzes the energy demand of the apartment building as the change of orientation and window to wall ratio among $46m^2$ and $84m^2$ type. In conclusion, when reducing the window to wall ratio, energy demand was reduced, except when the orientation of the building was between from +10 to -20 from the south.

• Journal of Hydrogen and New Energy
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• v.28 no.2
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• pp.190-199
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• 2017

Air-blown Gasification of coal and torrefied biomass mixture is conducted on fixed-bed gasifier. The various ratio (9:1, 8:2, 7:3) of coal and torrefied biomass mixture are used. The contents of $H_2$, CO in the syngas were increased with gasification temperature. Carbon conversion tend to increase with temperature and equivalence ratio (ER). However, cold gas efficiency showed maximum point in ER range of 0.26-0.36. The torrefied biomass showed highest cold gas efficiency of 67.5% at $934^{\circ}C$, ER 0.36. Gasification of 8:2 mixture showed the highest carbon conversion and cold gas efficiency and synergy effect.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.4
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• pp.215-224
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• 2009

Analysis for various driven nozzle position changes. The analysis was done for different Reynolds number in entrance region of jet-pump and for several diameter ratios of driven nozzle. (1) The largest absorption energy was found at the point s=1 in condition of diameter ratio 1:3.21 and point s=0.5 in condition of diameter ratio 1:2.25. (2) The absorption energy was not related to the change of entrance velocity and the driven nozzle position having the largest absorption energy was function for cross section ratio. (3) As the position of driven nozzle moves to the downstream, the absorption energy gets weaker. Because the energy from swirl was lost at the cross section gets smaller. (4) As the position of driven nozzle moves to the downstream, the injection energy leans to the upper direction wall and as the Reynolds number increase, the lean phenomenon is more distinct. (5) The flow quantity of driven nozzle, the diameter ratio 1:3.21, was 32% higher than that of 1 : 2.25 and as the inlet velocity gets faster the efficiency decreased. And as the cross section of the driven nozzle increases.

• KIEAE Journal
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• v.10 no.5
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• pp.95-100
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• 2010

Buildings receive solar radiation through windows and the solar radiation helps to save heating energy in winter. Therefore the bigger the glazing ratio is, the larger the amount of solar radiation we can receive. In this study we analysed the glazing ratio of Certified Green Building Apartments. And we verified whether the glazing ratio reflects energy saving through accepting solar radiation with correlation analysis. For glazing ratio analysis, we selected 116 apartment buildings of 19 apartment complexes that certified in 2008-2009 and took pictures of outside windows of the buildings. After that, we analysed the building's glazing ratio with 4 azimuth and checked distinction of the glazing ratio between 6 coupled azimuths. And we analysed the correlation between importance order of azimuth for energy saving and the glazing ratio change with the azimuth. The analysis showed that the glazing ratio does not reflect energy saving through accepting solar radiation.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.522-528
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• 2012

Currently, the energy consumption of electric lighting in an office building is accounted for more than 30% of the total energy consumption. In order to reduce the energy consumed by the indoor lighting, the daylight as a natural energy resource can play an important role in energy savings. The daylight can have positive impacts on improvement of work efficiency and productivity, and also make people feel more psychologically stable. Moreover, by using the daylight, we can definitely reduce the energy consumption in office buildings. Thus, the purpose of this study is to determine the LED dimming ratio depending on the ratio by calculating the amount of artificial illumination required according to the change of daylight by using the light simulation software that can quantify and visualize the performance of daylight. As a result, the energy savings could be obtained up to 30%.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.513-516
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• 2004

The purpose of this study is to investigate properties of porous concrete according to volume of binder and compaction energy. The result of this study, as compaction energy goes on increasing, the actual measured void ratio is decreased according as a change of compaction energy and volume of binder. The compaction energy has a very near value by target void ratio on the whole when it is $50kN{\cdot}m/m^2,\;50\~75kN{\cdot}m/m^2$ in case of target void ratio is $15\%\;and\;25\%$. As compaction energy goes on increasing, compressive strength of specimens picked up when target void ratio is $20\%\;and\;25\%$. Also, compressive strength of specimens bluntly picked up when compaction energy is over $50\~75kN{\cdot}m/m^2$.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.5
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• pp.73-85
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• 1999

Yield and fracture are separated in the tensile failure of paper. Failure in the machine direction of photocopy paper is contrasted with failure in the cross-machine direction . The ratios of distortion (shape change) to dilatation (volume change) for individual elements at yield and fracture are described. The ratios of distortion to dilatation are measured and compared to predicted values of the strain energy density theory. To evaluate the effect of the angle from the principal material direction on the strain energy density theory. To evaluate the effect of the angle from the principal material direction on the strain energy density factor, samples are prepared from machine direction to cross-machine direction in 15 degree intervals. the strain energy density of individual elements are obtained by the integration of stress from finite element analysis with elastic plus plastic strain energy density theory. Poison's ratio and the angle from the principal material direction have a great effect ion the ratio fo distortion to dilatation in paper. During the yield condition, distortion prevails over dilatation . At fracture, dilatation is at a maximum.