• Korean Journal of Materials Research
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• v.9 no.3
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• pp.269-273
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• 1999

Polycrystalline silicon films are generally deposited by LPCVD, utilizing the thermal decomposition of $SiH_4$ gas. When silicon wafers are loaded into the furnace in order to reduce oxygen concentration of the films, we flow 20slm N, gas from top to bottom of the furnace, and then deposit films of $1000\AA$ thickness to measure oxygen concen­tration by SIMS. As a consequence of SIMS, we obtain oxygen concentration in films lower about 30 times than that of films deposited with 20slm $N_2$ gas-flow through the short injector in the hatch of furnace. In our long injector system, we estimate a reproducibility by uniformity, particle, and Rs of the deposited films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.251-254
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• 2001

In this paper, we analyzed the properties change of electric wire when the thermal stress was applied to NFR-8 and FR-PVC 600[V] wire. Messurement is made of the attenuation of a light beam by smoke accumulating with in a closed chamber due to nonflaming pyrolytic decomposition and flaming combustion. Results are expressed in terms of specific optical density which is derived from a geometrical factor and the measured optical density a measurement characteristic of the concentration of smoke. Referenced documents were ASTM E662 standard test method for specific Ds genalated by solid materials. The furnace control system shall maintain the required irradiance level under steady-state condition with the chamber door closed of $2.5{\pm}0.04[w/cm^{2}]$ for 20 min. According to the results of the smoke density analysis of NFR-8 and FR-PVC the highest decomposition flaming smoke density range of NFR-8 and FR-PVC were 25.2 to 37.5 and 51.1 respectively. Nonflaming smoke density range of NFR-8 and FR-PVC were 100.4 to 112.2 and 126.5 to 398.8. The amount of carbon monoxide generated was found to be much higher in FR-PVC decomposition than in NFR-8 due to incomplete combustion of FR-PVC which has high content of carbon in compound.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.251-254
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• 2001

In this paper, we analysed the properties change of electric wire when the thermal stress was applied to NFR-8 and FR-PVC [600] wire. Measurement is made of the attenuation of a light beam by smoke accumulating with in a closed chamber due to nonflamining pyrolytic decomposition and flaming combustion. Results are expressed in terms of specific optical density which is derived from a geometrical factor and the measured optical density a measurement characteristic of the concentration of smoke. Referenced documents were ASTM E662 standard test method for specific Ds generated by solid materials. The furnace control system shall maintain the required irradiance level under steady-state condition with the chamber door closed of 2.5${\pm}$0.04[w/$\textrm{cm}^2$] for 20 min. According to the results of the smoke density analysis of NFR-8 and FR-PVC the highest decomposition flaming smoke density range of NFR-8 and FR-PVC were 7.2 to 77.5 and 51.1 respectively. Nonflaming smoke density range of NFR-8 and FR-PVC were 100.4 to 112.2 and 126.5 to 398.8. The amount of carbon monoxide generated was found to be much higher in FR-PVC decomposition than in NFR-8 due to incomp1ete combustion of FR-PVC which has high content of carbon in compound.

• Fire Science and Engineering
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• v.14 no.2
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• pp.7-13
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• 2000

We had investigated thermal stability, Ignition temperature and fire gas for polyurethane foams used for manikin, cushion and interior finishing material. Decomposition of polyurethane foams with temperature was investigated using a DSC and the weight loss with temperature increase using a TGA in order to find the thermal hazard of polyurethane foams, and the ignition temperature of polyurethane foams according to species. We studied constant temperature among ignition temperature measuring methods. In addition, noxious gases for polyurethane foams according to combustion condition were analyzed using gas analyzer and GASTEC. As results, initial decomposition temperature of polyurethane foam used for interior finishing material was lower than those for manikin and cushion, and exothermic energy was higher. Ignition temperature of polyurethane foam of interior finishing material was $420^{\circ}$. All of combustion forms at $427^{\circ}$ and under were smoldering combustion, and it was combustion at $500^{\circ}$. As furnace temperature was increased, concentration of noxious gases such as carbon oxide, carbon dioxide, and hydrogen cyanide was increased. And nitrogen oxide at combustion condition($500^{\circ}$) was over 10 ppm.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.126-129
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• 2007

The particle formation using pyrolysis has many advantages over other particle manufacturing techniques. The particles by pyrolysis have relatively uniform size and chemical composition. Also, we can easily produce high purity particles. Thus, we studied the formation of silicon particles by pyrolysis of 50% $SiH_4$ gas diluted in Ar gas. A pyrolysis furnace was used for the thermal decomposition of $SiH_4$ gas at $800^{\circ}C$ and atmospheric pressure. The aerosol flow from furnace is separated into two ways. The one is to the Scanning Mobility Particle Sizer (SMPS) for particle size distribution measurement and the other is to the particle deposition system. The produced silicon particles are deposited on the wafer in the deposition chamber. SEM measurement was used to compare the particle size distribution results from the SMPS. Depending on the experimental conditions, particles of high concentration in the $30\sim80$ nm size range were generated.

• Proceedings of the KAIS Fall Conference
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• 2000.10a
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• pp.39-41
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• 2000

Newly modified spray Pyrolysis system was developed to Produce ultra Pure and fine Powder by spray Pyrolysis Process. In this system, raw material solution was effectively atomized and sprayed into the reaction furnace. Also, thermal decomposition process fully completed in the three zone reaction furnace, and produced powder was effectively collected. A technology to reduce impurities in complex acid solution below 20ppm was also developed. The characteristics of produced powder were studied by changing the reaction conditions such as reaction temperature, the injection velocity of the solution and air, nozzle tip size and concentration of solution. The morphology of powder had spherical shape under the most experimental conditions, and the composition and the particle size distribution were almost uniform. Under the most experimental conditions average particle size of most produced powder was below 100nm.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1184-1189
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• 2004

Coking process is the thermal decomposition of bituminous coal with final temperature of about $900^{\circ}C$ Because coke plays important roles in ironmaking process in a blast furnace it's essential for developing modeling of coke oven. In this study, An unsteady 2-dimesional model is proposed to simulate coking process in a coke oven. In this model, gas and solid phase are assumed homogeneous continnum and solid bed is assumed as porous media . The model contains governing equations for the solid phase and the gas phase. Complicated phenomena such as swelling, softening, resolidification and shrinkage are neglected and mass loss by drying and devolatilization is reflected by generation of internal pores. Drying, devolatilization, heat transfer and generation of internal pores are also reflected in source terms. Calulated results are compared with experimental data

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.105-114
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• 2004

This study investigated the thermal behavior of the nuclear graphite waste generated from the decommissioning of the Korean nuclear research reactor, The first part study investigated the decomposition rate of the nuclear graphite waste up to $1000^{\circ}C$ under various oxygen partial pressures using a thermo-gravimetric analyzer (TGA). Tested graphite waste sample not easily destroyed in the oxygen-deficient condition. However, the gas-solid oxidation reaction was found to be very effective in the presence of oxygen. No significant amount of the product of incomplete combustion was formed even in the limited oxygen concentration of 4% $O_2$. The influence of temperature and oxygen partial pressure was evaluated by the theoretical model analysis of the thermo-gravimetric data. The activation energy and the reaction order of graphite oxidation were evaluated as 128 kJ/mole and 1.1, respectively. The second part of this study investigated the behavior of radioactive elements under graphite oxidation atmosphere using thermodynamic equilibrium model. $^{22}Na$, $^{134}Cs$ and $^{137}Cs$ were found be the semi-volatile elements. Since volatile uranium species can be formulated at high temperatures above $1050^{\circ}C$, the temperature of incinerator furnace should be minimized. Other corrosion/activation products, fission products and uranium were found to be the non-volatile species.

• Journal of Korea Society of Waste Management
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• v.35 no.8
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• pp.744-753
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• 2018

The Stockholm Convention, which was adopted in Sweden in 2001 to protect human health and the environment, includes regulations for Persistent Organic Pollutant Rotors such as toxic and bioaccumulatives. Currently, there are 28 types of materials. This prohibits and limits the production, use, and manufacture of products. Korea is a member of the Convention, and it is necessary to prepare management and treatment plans to address the POP trends. Thus, we experimentally investigate whether the environmentally stable incineration is achieved when the sample is thermally treated using the Lab-scale (1 kg/hr). The target samples is pesticides in liquid phase and solid phase. In this study, organic chlorinated pesticides and their thermal characteristics were analyzed. We calculated the theoretical air volume based on the element analysis results. Because the interior of the reactor is small, more than 10 times of the air ratio was injected. The retention time was set to at least 4 seconds using a margin. The incineration temperature was $850^{\circ}C$ and $1100^{\circ}C$. Thus, we experimentally investigated whether the environmentally stable incineration was achieved when the sample was thermally treated using the Lab-scale (1 kg/hr). We analyzed five types of exhaust gas; the 02 concentration was high, but the CO amount decreased. Complete combustion is difficult because of the small size of the furnace due to the nature of Lab-scale. The organic chlorine-containing pesticide had an average decomposition rate of 99.9935%. Considering the decomposition rates of organic chlorine-containing pesticide in this study, the incineration treatment at over 2 ton/hour, which is typical for a conventional incinerator, is possible. Considering the occurrence of dioxins and unintentional persistent organic pollutants, it can operate at more than $1,100^{\circ}C$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.2
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• pp.178-189
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• 1994

Fine $BaTiO_3$ powder was synthesized from the various starting solution with 0.05 M by ultrasonic spray pyrolysis method. The conditions of synthesis were fixed on flow rate was 0.5 cm/sec, low temperature furnace was $300^{\circ}C$, and high temperatures furnace was $700^{\circ}C$. The formation procedure was investigated directly by SEM with the collected particle from the each reaction step. Also, the trace of particle in reaction tube was researched theoretically. Fine $BaTiO_3$ was synthesized only in the case of nitrate aqueous solution. The synthesized $BaTiO_3$ powder was porous and spherical which was consist of primary particle at the size of 19.1 nm. The formation procedure was as follows : the particle size decreased in drying step and then increased in initial thermal decomposition step. Finally, particle size was decreased to $0.42 {mu}m$. The trace of particle in reaction tube was also theoretically simulated and discussed.