• Journal of ILASS-Korea
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• v.1 no.1
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• pp.55-62
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• 1996

In a fuel injection engine, atomization of liquid fuel and mixture formation process has influenced(or affected) directly on the engine performance and pollutant emission. In this study, the characteristics of fuel spray and the behaviors of secondary atomization developed at the downstream of the valves were investigated using an image processing method. Solid and perforated valves are chosen in order to evaluate the valve performance in terns of air flow rate, valve opening angle and valve shape. Experimental results clearly indicate that the spray atomization quality can be improved by increasing the perforated rat io and the blockage rat io in the perforated valve, the characteristics of spray atomization is improved by using the perforated valve with high perforated rat io and blockage ratio.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.419-425
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• 2024

The purpose of this study is to improve the concentration of U(VI) in carbonate solution reasonably, which to improve the application potential of the alkaline reprocessing processes. The dissolution behavior of U₃O₈ in carbonate peroxide solutions was investigated under different conditions, including pH, carbonate concentration, and solid-liquid ratio. The results showed that the dissolution rate of U₃O₈ increased with the increase of pH from 8 to 11 in the mixed carbonate solution containing 0.5 mol/L H₂O₂. The role of carbonate ions in the dissolution of U₃O₈ was further elucidated by observing the dissolution of UO₄⋅4H₂O in carbonate solutions. Furthermore, the concentration of U(VI) in 3 mol/L Na₂CO₃ solution was successfully increased to 350 g/L under ultrasonic-assisted conditions at 60 ℃ and a solid-liquid ratio at 1/2 g/mL. Meanwhile, it is suggested that increasing the concentration of carbonate ions can improve the stability of the dissolved solution containing uranyl peroxycarbonate complex.

• Journal of the Korea Institute of Building Construction
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• v.12 no.5
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• pp.548-557
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• 2012

In this study the thermal performance of G-PCM replaced for find aggregate in mortar specimens was evaluated using TG-DTA. As a result, it was found that when solid changed into liquid, it absorbed heat, and when liquid changed into solid, it radiated heat. In addition, the fluidity and the compressive strength of mortar with G-PCM can be applied to the floor mortar and a wall finish material. Also the higher the replacement ratio, the larger the latent heat capacity. It was found that the mortar with G-PCM slowed the increase and decrease of temperature. Thus, the duration of pleasant indoor temperature is extended by the floor and wall mortar with G-PCM. In conclusion, G-PCM is expected to reduce the heating energy consumption.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2212-2216
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• 2011

An ionic liquid-based ultrasonic-assisted extraction method has been successfully applied to the effective extraction of phenolic compounds from Laminaria japonica Aresch. Three kinds of 1-alkyl-3-methyl-imidazolium with different cations and anions were evaluated for extraction efficiency. The results showed that both the characteristics of anions and cations have remarkable effects on the extraction efficiency. In addition, the ionic liquid-based ultrasonic-assisted extraction procedure was also optimized on some extraction parameters, such as ultrasonic power, extraction time and solid-liquid ratio. Compared with the conventional solvent, the optimum approach gained the highest extraction efficiency within the shortest extraction time. Average recoveries of phenolic compounds were from 75.5% to 88.3% at three concentration levels.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.4
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• pp.285-296
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• 2005

In order to reduce the compression power and to use the overall energy contained in LNG effectively, a combined cycle is devised and simulated. The combined cycle is composed of two cycles; one is an open cycle of liquid/solid carbon dioxide production cycle utilizing LNG cold energy in $CO_2$ condenser and the other is a closed cycle gas turbine which supplies power to the $CO_2$ cycle, utilizes LNG cold energy for lowering the compressor inlet temperature, and uses the heating value of LNG at the burner. The power consumed for the $CO_2$ cycle is investigated in terms of a production ratio of solid $CO_2$. The present study shows that much reduction in both $CO_2$ compression power (only $35\%$ of power used in conventional dry ice production cycle) and $CO_2$ condenser pressure could be achieved by utilizing LNG cold energy and that high cycle efficiency ($55.3\%$ at maximum power condition) in the gas turbine could be accomplished with the adoption of compressor inlet cooling and regenerator. Exergy analysis shows that irreversibility in the combined cycle increases linearly as a production ratio of solid $CO_2$ increases and most of the irreversibility occurs in the condenser and the heat exchanger for compressor inlet cooling. Hence, incoming LNG cold energy to the above components should be used more effectively.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.492-496
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• 2014

In this work, the possibility of Miscanthus as renewable lignocellulosic biomass was evaluated for production of furfural. Also, to find the reaction conditions of furfural production from Miscanthus straw, the effects of solid-to-liquid ratio, reaction temperature, catalyst amount, and reaction time were investigated. Finally, 5.1 g/L furfural was produced from Miscanthus straw in the condition of solid-to-liquid ratio at 1:10, reaction temperature at $150^{\circ}C$, sulfuric acid at 3%, and reaction time of 60 minutes. This result will provide basic knowledge for converting renewable resources into valuable chemicals substituted for fossil fuels.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.2
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• pp.201-207
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• 2004

Dissolved air flotation (DAF) is a solid-liquid separation process that uses fine rising bubbles to remove particles in water. Most of particle-bubble collision occurs in the DAF contact zone. This initial contact considered by the researchers to play a important role for DAF performance. It is hard to make up conceptual model through simple mass balance for estimating collision efficiency in the contact zone because coupled behavior of the solid-liquid-gas phase in DAF system is 90 complicate. In this study, 2-phase(gas-liquid) flow equations for the conservation of mass, momentum and turbulence quantities were solved using an Eulerian-Eulerian approach based on the assumption that very small particle is applied in the DAF system. For the modeling of turbulent 2-phase flow in the reactor, the standard $k-{\varepsilon}$ mode I(liquid phase) and zero-equation(gas phase) were used in CFD code because it is widely accepted and the coefficients for the model are well established. Particle-bubble collision efficiency was calculated using predicted turbulent energy dissipation rate and gas volume fraction. As the result of this study, the authors concluded that bubble size and recycle ratio play important role for flow pattern change in the reactor. Predicted collision efficiency using CFD showed good agreement with measured removal efficiency in the contact zone. Also, simulation results indicated that collision efficiency at 15% recycle ratio is higher than that of 10% and showed increasing tendency of the collision efficiency according to the decrease of the bubble size.

• Journal of the Korean Ceramic Society
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• v.17 no.4
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• pp.208-212
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• 1980

In order to clarify the mechanism of the hydration of supersulphated slag cement, the experiments of suspension hydration were performed in the mixtures of slag+CaSO4+water or NaOH solutions with a liquid/solid ratio of 10. The liquid and solid phase of the suspension was chemically analysed and discussed. In the slag-$CaSO_4$--NaOH system, $Al_2O_3$ was dissolved under high pH condition, and the ettringite was formed by a reaction of $CaSO_4$ and $Al_2O_3$ released in the solution. As hydration progressed, ettringite coated the surface of unhydrated slag grains and inhibited the hydration reaction of slag. $CaSO_4$ was not only an activator for slag hydration, but a reactant in the hydration.

• Solar Energy
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• v.4 no.2
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• pp.43-49
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• 1984

Experiments were performed to study freezing on a finned vertical tube when either conduction in the solid or natural convection in a liquid controls the heat transfer. Conduction is the controlling mode when the liquid is at its fusion temperature, whereas natural convection controls when the liquid temperature is above the fusion value. The liquid was housed in a cylinderical containment vessel whose surface was maintained at a uniform, time-invariment temperature during a data run, and the freezing occurred on a finned vertical tube positioned along the axis of the vessel. The phase change medium was n-octacosan, a paraffin which freezes at about $61^{\circ}C$. For conduction-controlled freezing, the enhancement of the frozen mass due to finning is greatest when the frozen layer is thin and decrease as the layer grows thicker. The degree of enhancement is generally less than the surface area ratio of the finned and unfinned tube.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.628-632
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• 2001

The removal rate of Cl from municipal solid waste incineration(MSWI) ash(bottom ash and fly ash) by washing was investigated. The Cl contents in the bottom ash and fly ash were 2.6-3.0% and 25-30% respectively, and KCl, NaCl, CaCIOH and friedel's salt were main components. From the results on the effects of washing time and temperature, the Cl contents in the bottom ash and fly ash were decreased up to 0.3% and 2.0% respectively by using of water as a solvent within 30 min at 2$0^{\circ}C$, 300 rpm of agitation speed and 10 of liquid/solid ratio. It is expected that the removal of Cl from the incineration ash by washing could make use of the ash for a cement raw material and so on.