• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.1
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• pp.1-8
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• 2011

A coupled thermal/structural analysis of mechanical ablation is performed based on domain/boundary decomposition and finite element method. The ablative material non-linearity and boundary non-linearity can be easily localized within a few subdomains and/or on the boundary interfaces. An enthalpy method is applied to simplify the effect of heat of pyrolysis in the ablative subdomains. In addition, maximum in-plane shear stress is considered as a surface recession criterion for the mechanical ablation simulation. The basic characteristics of the proposed method are examined carefully through numerical experiments.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.311-314
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• 2009

A two-dimensional thermal response and ablation simulation code for predicting charring material ablation and shape change on solid rocket nozzle is presented. For closing the problem of thermal analysis, Arrhenius' equation and Zvyagin's ablation model are used. The moving boundary problem and endothermic reaction in thermal decomposition are solved by rezoning and effective specific heat method. For simulation of complicated thermal protection systems, this method is integrated with a three-dimensional finite-element thermal and structure analysis code through continuity of temperature and heat flux.

• Microbiology and Biotechnology Letters
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• v.34 no.3
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• pp.216-220
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• 2006

Thermophillic fungus Thermoascus aurantiacus showed excellent growth and produced high amount of alcohol oxidase and catalase in a pectin medium. Besides, the strain produced enzymes which related with pectin or alcohol decomposition. We detected extracellular pectin esterase (EC 3.1.1.11) activity and, both intracellular and extracellular pectinase (EC 4.2.2.10) activity, as pectinolytic enzymes produced by T. aurantiacus. The production of methanol decomposition enzymes, such as alcohol oxidase (AOD, EC 1.1.3.13), alcohol dehydrogenase (ADH, EC 1.1.1.1), formaldehyde dehydrogenase (FADH, EC 1.2.1.1) and formate dehydrogenase (FDH, EC 1.2.1.2) follows by pectin esterase reaction which is converted to methanol. We concluded that T. aurantiacus has pectinolytic and alcohol - oxidative enzymological mechanism which produced carbon dioxide as a final material, started from pectin.

• Asian Journal of Atmospheric Environment
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• v.2 no.2
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• pp.75-80
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• 2008

A new-type apparatus decomposing volatile organic compounds (VOCs) using a combination system of an electrical exothermic SiC honeycomb and a catalytic filter was developed. This linear combination system is very useful to the catalytic decomposition of VOCs, because the gas involving VOCs is well heated in the SiC honeycomb and then flows into the catalytic filter. In the proposed apparatus, the outlet gas temperatures of SiC honeycomb maintained at ca. $300^{\circ}C$ after 5 min from the starting of applying electric current, and sufficient for the catalytic degradation of VOC components, i.e. toluene, isopropanol, methyl ethyl ketone and ethyl acetate. The average decomposition rate of total VOCs exhausted from a printing factory was 85% using pt catalyst at SV=19,000 in this system.

• Bulletin of the Korean Chemical Society
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• v.21 no.1
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• pp.101-104
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• 2000

Li-graphite intercalation compounds (GICs), synthesized at elevated temperature and pressure, were allowed to decompose spontaneously in the atmosphere. The decomposition processes were analyzed by of X-ray diffraction, DSC analysis, FT-IR measurements, UV/VIS spectrophotometry. The deintercalation reaction of the Li-GICs ceased after 6 weeks and only the residual compounds could be observed. A strong exothermic reaction was observed at 300 $^{\circ}C$ in thermal decomposition, and relatively stable decomposition curves were formed. A few endothermic curves have been observed at 1000 $^{\circ}C.$ After 6 weeks deintercalation reaction time of GICs, many exothermic and endothermic reactions were accompanied at the same time. In addition the reactions of the functional groups such as aromatic rings, nitrogen, $-CH_3$, $-CH_2$ etc. of GDIC obtained by the above reaction were confirmed by FT-IR spectrum. UV/VIS spectrophotometric measurement clearly shows the formation of a minimum energy value ($R_{min}$) for the compounds between Li-GICs as a starting material and Li-GDICs obtained until after 3 weeks of the deintercalation reaction, while they were no clear energy curves from 4 weeks of reaction time, because of the formation of the graphite structure, of high stages and of the Li compounds surrounding the graphite in the deintercalation reaction.

• Journal of KSNVE
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• v.4 no.3
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• pp.295-305
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• 1994

The reflection coefficient of a material at oblique incidence is measured in a free field. The sound pressure distributions are measured at discrete points on two measurement lines and then decomposed into plane wave components by using spatial Fourier transform. The inciedent and reflected plane wave components are obtained from a set of "decomposition equations" of which uses the plane wave propagation theory. Numerical simulations and experiments have been performed to see the effect of finite size of measurement area. To reduce this effect, a window fuction has been performed to see the effects of finite size of mesurement area. To reduce this effect, a window function has been proposed and its effect on the measurement of sound absorbing material property has been studied as well. The reflection coefficient obtained by this method is compared with those obtained from other methods; 2-microphone method in a duct and an expirical equation of which determines the characteristic impedance .rho.c and propagation constant k of a material from flow resistance information.formation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.6
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• pp.478-481
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• 2013

Diameter controlled carbon nanotubes (CNTs) were grown using surface modified iron nano-particle catalysts with aminpropyltriethoxysilane (APS). Iron nano-particles were synthesized by thermal decomposition of iron pentacarbonyl-oleic acid complex. Subsequently, APS modification was done using the iron nano-particles synthesized. Agglomeration of the iron nano-particles during the CNT growth process was effectively prevented by the surface modification of nano-particles with the APS. APS plays as a linker material between Fe nano-particles and $SiO_2$ substrate resulting in blocking the migration of nano-particles. APS also formed siliceous material covering the iron nano-particles that prevented the agglomeration of iron nano-particles at the early stages of the CNT growth. Therefore we could obtain the diameter controlled CNTs by blocking agglomeration of the iron nano-particles.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.6
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• pp.143-153
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• 2001

Hog manure amended with sawdust (moisture 56~60% wet basis, C/N 19-21) was composted in pilot-scale vessels using continuous aeration(CA) and intermittent aeration(IA) for 3 and 4 weeks. In two subsequent runs of the same duration, composts resulting from each of the first runs were used as a biofilter on the exhaust gas from newly composting material. Conditions between each of these paired sets appeared to be similar. Ammonia was released from the biofilter material during the first week of stabilization while the compost produced ammonia after the first week of composting. In both cases substantial absorption, 61~96 %, of ammonia production from the composting raw material was achieved in the stabilizing material during the final weeks of operation and indicates the use of the stabilizing hog manure/sawdust compost as a biofilter can reduce ammonia emissions. Total $NH_3-N$ emissions during run 2 in IA was less than 2/3 of those in CA. Dry solids loss for the stabilized compost (6~8 weeks) was 19~46%.

• Environmental and Resource Economics Review
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• v.14 no.2
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• pp.257-290
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• 2005

Korean energy use in industrial sector has increased more rapidly than other sectors during 1980~2000 periods. Relatively higher increases in industrial sector energy consumption raise questions whether government policy of rationalization of industrial energy use has been effective. In this study, we use 80-85-90 and 90-95-00 constant price input-output table to analyze increases in industrial energy use. Using an adjusted version of structural decomposition model introduced by Chen and Rose (1990), we decompose Changes of energy use into 17 elements. We classify entire industry sector into 32 sectors including four energy sectors (coal and coal products, refined petroleum, electricity and town gas). We then analyze changes of energy use by industrial level to check differences among industrial energy demand structures. Finally, we compare three industries, electronic product manufacturing, metal manufacturing and construction, that represent technology and capital intensive, energy and material intensive and labor and capital intensive industry. As results, we find that high energy using industries make the most effort to reduce energy use. Primary metal, petrochemical and mon-metal industries show improvements in elements such as energy and material productivity, energy and material imports, energy substitution and material substitutions towards energy saving. These results imply that although those industries are heavy users of energy, they put the best effort to reduce energy use relative to other industries. We find various patterns of change in industrial energy use at industrial level. To reduce energy use, electronic product manufacturing industry needs more effort to improve technological change element while construction industry needs more effort to improve material input structure element.

• Korean Journal of Materials Research
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• v.22 no.5
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• pp.253-258
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• 2012

Activated magnetite ($Fe_3O_{4-{\delta}}$) was applied to reducing $CO_2$ gas emissions to avoid greenhouse effects. Wet and dry methods were developed as a $CO_2$ removal process. One of the typical dry methods is $CO_2$ decomposition using activated magnetite ($Fe_3O_{4-{\delta}}$). Generally, $Fe_3O_{4-{\delta}}$ is manufactured by reduction of $Fe_3O_4$ by $H_2$ gas. This process has an explosion risk. Therefore, a non-explosive process to make $Fe_3O_{4-{\delta}}$ was studied using $FeC_2O_4{\cdot}2H_2O$ and $N_2$. $FeSO_4{\cdot}7H_2O$ and $(NH_4)_2C_2O_4{\cdot}H_2O$ were used as starting materials. So, ${\alpha}-FeC_2O_4{\cdot}2H_2O$ was synthesized by precipitation method. During the calcination process, $FeC_2O_4{\cdot}2H_2O$ was decomposed to $Fe_3O_4$, CO, and $CO_2$. The specific surface area of the activated magnetite varied with the calcination temperature from 15.43 $m^2/g$ to 9.32 $m^2/g$. The densities of $FeC_2O_4{\cdot}2H_2O$ and $Fe_3O_4$ were 2.28 g/$cm^3$ and 5.2 g/$cm^3$, respectively. Also, the $Fe_3O_4$ was reduced to $Fe_3O_{4-{\delta}}$ by CO. From the TGA results in air of the specimen that was calcined at $450^{\circ}C$ for three hours in $N_2$ atmosphere, the ${\delta}$-value of $Fe_3O_{4-{\delta}}$ was estimated. The ${\delta}$-value of $Fe_3O_{4-{\delta}}$ was 0.3170 when the sample was heat treated at $400^{\circ}C$ for 3 hours and 0.6583 when the sample was heat treated at $450^{\circ}C$ for 3 hours. $Fe_3O_{4-{\delta}}$ was oxidized to $Fe_3O_4$ when $Fe_3O_{4-{\delta}}$ was reacted with $CO_2$ because $CO_2$ is decomposed to C and $O_2$.