• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.524-527
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• 2004

Hybrid rocket had many advantage with compared to solid and liquid rockets. However, the engines have not yet been used in practical rocket systems, due mainly to the disadvantage of hybrid combustion, such as low fuel regression rate. In this study, lab-scale hybrid motor was designed and manufactured. And the methods of regression rate improvement were considered. Test firings with thrusts up to 300 N were conducted with GOX and transparent PMMA. Thrust was calculated with the pressure of the combustion chamber and the regression rate was measured in with variation of oxidizer flow rate. The regression rates showed a strong dependency on GOX mass flux. The frequency analysis technique of the bulk-mode oscillation of motor was applied to a hybrid rocket motor and was based on the principle that this frequency was inversely proportional to the square root of the chamber volume. Several problems and solutions of operating hybrid rocket were presented.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.941-952
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• 2012

In the present contribution the Encounter Theory (ET) (the prototype of the classical Collision Theory in rarefied gases) concepts for widely occurring diffusion assisted irreversible bulk reactions A + A ${\rightarrow}$ C and A + B ${\rightarrow}$ C in liquid solutions examined by the authors in the literature are analyzed and compared with each other for these different types of reactions. It is shown that for a particular case of equal initial concentrations $[A]_0=[B]_0$ in the reaction A + B ${\rightarrow}$ C, when the kinetics of both reactions A + A ${\rightarrow}$ C and A + B ${\rightarrow}$ C in the framework of formal chemical kinetics and ET are the same, the accumulation of macroscopic correlations breaking the concepts of independent encounters and leading to the Generalized Encounter Theory (GET) are drastically different. The influence of the force interaction and the decay of nonstable reactants on the time behavior the macroscopic correlations is also briefly discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.477-480
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• 1998

Sol-gel processing, which started some decades back as a laboratory curiosity, has proved to be a powerful and versatile technique for the synthesis of materials. The utility of the sol-gel method for producing glass and ceramic materials in the form of powders, fibers, thin films and bulk shapes with high purity, functional microstructures and potentially high chemical homogeneity at relatively low temperature (compared to conventional processing) has been discussed.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.857-864
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• 2011

Oxy-fuel combustion with many advantages such as high combustion efficiency, low flue gas flow rate and low NOx emission has emerged as a promising CCS technology for coal combustion facilities. In this study, the effects of the direct sulfation reaction on $SO_2$ removal efficiency were evaluated in a drop tube furnace under typical oxy-fuel combustion conditions represented by high concentrations of $CO_2$ and $SO_2$ formed by gas recirculation to control furnace combustion temperature. The effects of the operating parameters including the reaction temperature, $CO_2$ concentration, $SO_2$ concentration, Ca/S ratio and humidity on $SO_2$ removal efficiency were investigated experimentally. $SO_2$ removal efficiency increased with reaction temperature up to 1,200 due to promoted calcination of limestone reagent particles. And $SO_2$ removal efficiency increased with $SO_2$ concentrations and the humidity of the bulk gas. The increase of $SO_2$ removal efficiency with $CO_2$ concentrations showed that $SO_2$ removal by limestone was mainly done by the direct sulfation reaction under oxy-fuel combustion conditions. From the impact assessment of operation parameters, it was shown that these parameters have an effects on the desulfurization reaction by the order of the Ca/S ratio > residence time > $O_2$ concentration > reaction temperature > $SO_2$ concentration > $CO_2$ concentration > water vapor. The semi-empirical model equation for to evaluate the effect of the operating parameters on the performance of in-furnace desulfurization for oxy-fuel combustion was established.

• Applied Chemistry for Engineering
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• v.21 no.4
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• pp.469-474
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• 2010

Wood has an essential drawback such as high combustion ability. The purpose of this paper is to examine the combustion properties of the quercus variabilis and zelkova serrata dried at room temperature. The cone calorimeter (ISO 5660-1) was used to determine the heat release rate (HRR) and fire smoke index, as well as CO/$CO_2$ production and smoke obscuration. The total heat release (THR), $140.2\;MJ/m^2$ of the quercus variabilis under an external $50\;kW/m^2$ was high in comparison with THR $85.7\;MJ/m^2$ for the zelkova serrata. Furthermore, the quercus variabilis has high total smoke production (TSP), $3.50\;m^2$ compared with TSP $0.65\;m^2$ of zelkova serrata. Thease results depend on the bulk density of tested wood species. In addition, the CO/$CO_2$ production ratio of zelkova serrata and quercus variabilis was measured as 0.053, 0.043, respectively. Also, zelkova serrata showed an increase of fire-resistance attributed to char formation compared with that of quercus variabilis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.9
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• pp.1178-1184
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• 1999

The in-cylinder flow field of gasoline engine comprises unsteady compressible turbulent flows caused by the intake port, combustion chamber geometry and the change of the spatial shape. Thus the quantitative analysis of the in-cylinder bulk flow plays an important role in the improvement of engine performances and the reduction of exhaust emission. The influences of tumble intensifying valve (TIV) and swirl intensifying valve (SIV), and various intake-flow conditions are compared with the tumble ratio obtained by the measured results of the in-cylinder gas flow. In order to obtain the quantitative analysis of the in-cylinder gas flows of gasoline engine this investigation applied the particle tracking method to the analysis of gas flow characteristics. Various intake conditions such as tumble and swirl intensifying valve, the deactivated condition of one valve among two intake valves, and the other factors of gas flow are considered.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.4
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• pp.78-83
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• 2010

In this study, the possibility of the use of a new raw material in paperboard industry was investigated. Fly ash is one of the residues generated in the combustion of coal and generally captured from the chimney of coal-fired power plant. This material is utilized in many industries including cement, soil stabilization, composite etc., but it is not used in paper industry. Three types of fly ashes were collected from Hadong, boryeong and Seocheon steam power plants and we investigated their properties by scanning electron micrographs and particle size distribution. Papers were manufactured with KOCC and fly ashes, and the physical properties such as bulk, tensile strength, internal bond strength and ISO brightness were measured to identify the effects of fly ash on the paper properties.

• Clean Technology
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• v.22 no.4
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• pp.286-291
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• 2016

In this study we made fuel pellet from miscanthus biomass and investigated changes of physiological characteristics and electricity consumption of pelletizing process in comparison with fuel pellet made of pine sawdust. We also examined combustion characteristics including ash content and clinker forming ratio with fuel pellet made of mixing with micanthus biomass and lime powder. Bulk density of ground-miscanthus and pine sawdust were $158g\;L^{-1}$ and $187g\;L^{-1}$, respectively. Bulk density of ground miscanthus was lower than that of pine sawdust, but increased to $653g\;L^{-1}$ after pelletizing, which was similar to $656g\;L^{-1}$ of pine sawdust pellet. Moisture content in raw miscanthus and ground miscanthus were 17.0% and 11.8%, respectively. Moisture content in ground miscanthus was similar to that of pine saw dust and decreased to 6.73% after pelletizing, which was 7.7% lower than that of pine sawdust pellet. Although $27kWh\;ton^{-1}$ were required for compaction press that was an additional process in miscanthus pelleitizing, total required electricity was $193kWh\;ton^{-1}$ which was similar to $195kWh\;ton^{-1}$ of pine sawdust pellet pelleitizing. Pellet durability and pelletizing ratio of miscanthus were 98.0% and 99.7%, respectively, which were similar to 98.1% and 99.4% of pine sawdust pellet. When lime mixing ratio increased, ash melting degree and clinker forming ratio of miscanthus pellet increased. While higher heating value and clinker forming ratio of miscanthus pellet decreased.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.11
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• pp.957-964
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• 2010

The deflagration-to-detonation transition (DDT) causes a strong pressure wave that can adversely affect surrounding structures. The pressure generated by multiple detonative pulses is strong enough to cause metal surface erosion and chipping of the edges of bulk structures. In this study, we investigate the damage caused by the DDT phenomenon and perform hydrocode simulations to evaluate the structural damage caused to a metallic pulverized-coal injector used in a pulverized-coal-oxygen combustion furnace. The experimental conditions are selected in order to accurately model the damage caused to metal injectors that are exposed to multiple DDT pulses.

• Fire Science and Engineering
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• v.24 no.3
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• pp.86-92
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• 2010

One of the limitation of wood as building materials is its flammability. The purpose of this paper is to examine the combustion properties of the Pinus rigida and Castanea savita which are grown in Korea and meet the desirable characteristics for use of construction materials. The cone calorimeter (ISO 5660-1) was used to determine the heat release rate (HRR) and fire smoke index, as well as CO and $CO_2$ production and smoke obscuration. The $HRR_{mean}$ of the Castanea savita and Pinus rigida at $50\;kW/m^2$ of radiant heat flux was $70.4\;kW/m^2$ and $68.5\;kW/m^2$. Furthermore, the THR of Castanea sativata was 120.8 MJ/kg and it was higher than the THR of Pinus rigida ($81.9\;MJ/m^$). These results are depend on the bulk density of tested wood species. The Castanea savita has high $CO_{mean}$ yield and high CO/$CO_2$ yield compared with that of Pinus rigida.