• Journal of the Korean Society of Tobacco Science
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• v.17 no.2
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• pp.160-169
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• 1995

A mathematical model for the pyrolysis processes during unforced smoldering of cigarette was proposed in this study by analyzing the physical model of the smoldering cigarette (including the establishment of burning front between burning zone and pyrolysis zone, and analyzing the involvement of main factors such as pyrolysis of virgin tobacco, evaporation of water, and internal heat transport in the processes). Thermal conduction of cigarette paper and convective and radiative heat transfer at the outer surface were also considered via the thermal resistance law for the competitive heat transfer mechanisms. The governing partial differential equations were solved using an integral method. Model predictions of smoldering speed, or linear burn rate, as well as temperature and density profiles in the pyrolysis zone for different kinds of cigarettes were found to be close to the experimental data in the literature (Muramatsu, 1981). The model provides a relatively fast and efficient way to simulate the pyrolysis processes and offers a practical tool for exploring important parameters for a smoldering cigarette, such as blended tobacco composition, properties of cigarette paper, and heat flux from the burning zone to the pyrolysis zone.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.4
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• pp.479-485
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• 1996

Volatile organic compounds are air pollutants exhausting from industrial process, evaporation of solvent, and so on. Most of VOCs are the combustible gas of low calorific value as it is diluted by air. The systems burning such a hazardous gas need to increase enthalpy in order to increase flame stability. In this study an incinerator with reciprocating flow in the honeycomb ceramic has been used for the experiment of VOCs control. By the reciprocating flow system, the enthalpy of combustion gas is effectively regenerated into the enthalpy increases of the combustible gas through the honeycomb ceramic, which provides a heat storage. The position of the reaction zone is strongly dependent on the parameters of mixture velocity and time frequency. Flame front is changed to the point where burning velocity is coincided with burning velocity in the honeycomb ceramic. In this system it is important that flame front should be located symmetrically at the center of honeycomb ceramic for the purpose of increasing the reaction rate at one point. Peak temperature becomes higher with decreasing time frequency, at which the flow direction is regularly reversed.

• KEPCO Journal on Electric Power and Energy
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• v.1 no.1
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• pp.93-97
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• 2015

The combustion tests for Korean anthracite-bituminous coal blend were carried out in the 200 MW utility boiler. The burning characteristics of the blend were studied with a thermogravimetric analyzer (TGA). From the observation of TGA burning profiles, it was found that the presence of bituminous coal in the blend appeared to enhance the reactivity of anthracite in the higher temperature region, indicating certain interactions between the two coals. The plant test showed the boiler operation was reasonably stable with somewhat poor combustion efficiency, and some modification of the combustion environment in the furnace is necessitate for the further stable plant operation.

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.2
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• pp.109-117
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• 2005

In this study, the 1/20 reduced-scale experiments using Froude scaling were conducted to investigate the ventilation velocity of the variation of burning rate in tunnel fires. The heptane square pool fire with heat release rate ranging from 3.71~15.6 kW were used. The burning rate of fuel was obtained by measuring mass using load cell and temperature distributions were measured by K-type theomocouples in order to investigate smoke movement. The ventilation velocity in the tested tunnel was controlled by inverter of the wind tunnel. In heptane pool fire case, the increase in ventilation velocity incresed the burning rate due to the direct supply of oxygen to the fire plume. For the same dimensionless velocity($\bar{V}$), burning rate increased as the size of pool fire decreased.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.61-65
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• 2005

In HTPB/AP propellants, zirconium(Zr) addition to formulation was shown to be less specific impulse than aluminum(Al) by the theoretical calculation because of the lower flame temperature and higher molecular weight of Zr oxide. It was found that the burning rate was faster with the finer size of Zr and the more content of $2{\mu}m$ Zr the faster burning rate is in HTPB/AP/Zr propellants caused by the more conduction energy transfer from Zr flame to the burning surface. Also the burning rate of HTPB/AP/Zr propellant could be reduced by addition of 150nm Al, depending on AP size distribution in formulation with Butacene and $1{\mu}m$ AP.

• Journal of Ginseng Research
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• v.11 no.2
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• pp.91-100
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• 1987

This study was investigated and analyzed the side of phenomenological of the chlorophyll bleaching phenomenon on the leaf burning-disease of the Ginseng (Panax ginseng C.A. Meyer) leaf. Red light (660-700 nm) was confirmed as one which induced the bleaching phenomenon and blue light (400-500 nm) did not at all. Temperature as 1 environmental factor had not any influence on chlorophyll bleaching phenomenon at all. Therefore, simple burning (thermal damage) hypothesis was perfectly ruled out by the result of this study. And, low pH accelerated chlorophyll bleaching velocity. A primary factor of chlorophyll bleaching phenomenon may be peculiar structural difference of the Ginseng leaf compared with other plant.

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.69-69
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• 2017

Flame arrestor as end of line flame arrester for endurance burning prevents a light-back at deflagration and stabilized burning (during and after endurance burning) of potentially explosive vapor-air and gas-air mixtures at the end of vent pipes. In a flame arrestor, spring is an important part. The spring load as well as the spring's elasticity determine when the hood is opened. In addition, the spring have to work in high temperature condition due to gas burning. Therefore, it is necessary to analyze mechanical load and elasticity of spring when gas is burned. Based on the dynamic calculation on working process of a specific flame arrestor, analysis of spring is taken. A three dimensional model for spring burned in flame arrestor by using CFD simulation. Results of the CFD analysis are input in FEM simulation to analyze structure of the spring. The simulation results can predict and estimate the spring's load and elasticity at variation of the spring's deflection. Moreover, the obtained result can provide makers with references to optimize design of spring as well as flame arrestor.

• Journal of the Korean Society of Combustion
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• v.16 no.2
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• pp.23-32
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• 2011

To investigate cell formation in hydrocarbon/hydrogen/carbon monoxide-air premixed flames, the outward propagation and cellular instabilities were experimentally studied in a constant pressure combustion chamber at room temperature and elevated pressures. Unstretched laminar burning velocities and Markstein lengths of the mixtures were obtained by analyzing high-speed schlieren images. In this study, hydrodynamic and diffusional- thermal instabilities were evaluated to examine their effects on flame instabilities. The experimentally-measured unstretched laminar burning velocities were compared to numerical predictions using the PREMIX code. Effective Lewis numbers of premixed flames with methane addition decreased for all of the cases; meanwhile, effective Lewis numbers with propane addition increased for lean and stoichiometric conditions and increased for rich and stoichiometric cases for hydrogen-enriched flames. With the addition of propane, the propensity for cell formation significantly was diminished, whereas cellular instabilities for hydrogen-enriched flames were promoted. However, similar behavior of cellularity was obtained with the addition of methane to the reactant mixtures.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.2
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• pp.9-16
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• 2005

Zirconium(Zr) addition to formulation of HTPB/AP propellants, was shown to be less specific impulse than aluminum(Al) by the theoretical calculation because of the lower flame temperature and higher molecular weight of Zr oxide. It was found that the burning rate was faster with the finer size of Zr and the more content of $2{\mu}m$ Zr the faster burning rate is in HTPB/AP/Zr propellants caused by the more conduction energy transfer from Zr flame to the burning surface. Also the burning rate of HTPB/AP/Zr propellant could be reduced by addition of 150nm Al, depending on AP size distribution in formulation with Butacene and $1{\mu}m$ AP.

• Journal of the Korean Ceramic Society
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• v.47 no.5
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• pp.401-406
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• 2010

For the lower-temperature preparation of calcium monoaluminate(CA, C:CaO, A:$Al_2O_3$) clinker which is hard to synthesize purely within its melting point, an equimolar hydrate was obtained and then used as a starting raw material of clinker burning. The hydrate was prepared from a mixture of waste oyster shell and industrial aluminium hydroxide by heating to $1200^{\circ}C$, grinding and mixing with water. The hydrate was composed of amorphous aluminium hydroxide and $C_3AH_6$(H:$H_2O$) formed by resolution-precipitation mechanism of the system C-A-H. By heating the hydrate, nearly pure and porous calcium monoaluminate clinker was formed at $1400^{\circ}C$ which is fairly lower temperature than that of its melting point. The formation of calcium monoaluminate was performed mainly by the reaction between amorphous alumina and $C_{12}A_7$ caused by the decomposition of $C_3AH_6$. The immediate and earlier formation of $C_{12}A_7$ seemed to be accelerated by not only high surface area and instability of the thermally decomposed hydrate but also the catalytic effect of water decomposed from the hydrate. The final calcium monoaluminate clinker was very porous because of the influence of highly porous shape of the thermally decomposed hydrate.