• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.1
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• pp.86-90
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• 2000

The mixed body of clay and flyash containing unburnt carbon was examined at various sintering conditions in order to recycle flyash as environment-affinitive construction materials. Experimental results can be summarized as follows : when large aggregate of 2.54 cm dia. was sintered at a heating rate of $20^{\circ}C$/min, heterogeneous phase with bulgings, inner pores, and cracks were observed at the sintering temperature of $1200^{\circ}C$. Accordingly, heating patterns for the complete removal of the heterogeneous phase were proposed as countermeasures. The compressive strength of finally obtained aggregate was 670~870kg/$\textrm{cm}^2$, which is over two and a half times stronger than the minimum requirement of 200kg/$\textrm{cm}^2$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.2
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• pp.947-953
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• 2012

In this study we investigated the manufacturing method for the activated carbon using the char from the pyrolysis of waste tire. The physical activation method using the steam in the fixed-bed quartz reactor was used for preparation of activated carbon. The primary experiment parameters are the activation temperature, activation time, heating rate, and the injection quantity of active agent. From the results of pore distribution of activated carbon, the micropore which was made in $850^{\circ}C$ of activation temperature, $5^{\circ}C$/min of heating rate, and 3 hours of activation time was developed in biggest quantity, and mesopore and macropore were developed in the biggest quantity too. The optimum conditions for producing the activated carbon using the pyrolysis residue were $850^{\circ}C$ of activation temperature, 3 hours of activation time, $5^{\circ}C$/min of heating rate, and 3 g $H_2O/char-g{\cdot}hr$ of active agent through this study. The produced activated carbon in these conditions showed that the potentiality of utilization as activated carbon because the BET specific surface area was $517.6m^2/g$ and total pore volume was $0.648cm^3/g$.

• Journal of the Korean Wood Science and Technology
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• v.44 no.5
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• pp.685-694
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• 2016

In this study, the thermal degradation behavior of biomass during torrefaction was studied by thermogravimetric and byproduct gas analysis. Torrefaction temperature, time, and heating rate were $220{\sim}300^{\circ}C$, 110 min, and $10{\sim}30^{\circ}C/min$, respectively. The degradation rate of yellow poplar was 8.01~8.81% at $220^{\circ}C$ and 71.86~77.38% at $300^{\circ}C$ depending on heating rate. The degradation rate significantly increased at temperature over $240^{\circ}C$. On the other hand, degradation rate of larch was relatively low as 49.58~54.15% at $300^{\circ}C$. The activation energy of yellow poplar was 87.32~91.24 kJ/mol; these values did not significantly change with heating rate. The activation energy of larch was 83.85~91.60 kJ/mol. The major components of the gas generated during torrefaction were derived from hemicellulose. The component types and concentrations increased with torrefaction severity. High concentrations of furfural and acetic acid were detected during torrefaction of yellow poplar.

• Journal of the Korean Ceramic Society
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• v.27 no.8
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• pp.1020-1026
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• 1990

The effect of heating rate on the microstructural evolution during sintering of PZT ceramics has been investigated. In case of PZT powder compacts containing excess of PbO, fast heating caused incomplete rearrangement of solid grains in a liquid, resulting in lower density and inhomogeneous pore shape ; on contrary, slow heating resulted in better densification. In contrast, in case of compacts without excess PbO, the densification was enhanced by fast heating due to suppression of the grain growth.

• Polymer(Korea)
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• v.35 no.3
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• pp.196-202
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• 2011

The cure kinetics of a bisphenol A epoxy resin and polyoxypropylene diamine curing agent system are investigated in both dynamic and isothermal conditions by differential scanning calorimetry (DSC). In dynamic experiments, the shift of exothermic peaks obtained at different heating rates is used to obtain activation energy of overall cure reaction based on the methods of Ozawa and Kissinger. Isothermal DSC data at different temperatures are fitted to an autocatalytic Kamal kinetic model. The kinetic model is in a good agreement with the experimental data in the initial stage of cure. A diffusion effect is incorporated to describe the later stage of cure, predicting the cure kinetics over the whole range of curing process. Also, dynamic mechanical analysis is performed to evaluate the storage modulus and average molecular weight between crosslinkages.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.907-918
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• 2000

The pyrolysis characteristics of celluloses and plastics, which are the principal materials contributing to the municipal solid wastes(MSWs), was investigated with a thermal gravimetric analysis reaction system. The experiments were carried out in a nitrogen atmosphere in the temperature range of 400~900K at various experimental conditions. Also, a modified pyrolysis model for compressed MSWs has been proposed. Varing the heating rate to 20, 30, 40K/min, reaction orders of MSWs' main component were around 1.1~1.9, activation energies were 117~166kJ/mol for celluloses and 187~239kJ/mol for plastics. Char yield was proportional to the heating rate, particle size, and compressed ratio. The model proposed in this study, which is applying Arrhenius equation and thermodynamics, is closer to the experimental results than the conventional model.

• Clean Technology
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• v.19 no.3
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• pp.279-286
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• 2013

Using a cation exchange resin of polystyrene-DVB copolymer as a carbon source for the production of activated carbon, the effects of operating parameters on the physical properties of activated carbon such as specific surface area and specific pore volume were experimentally studied. In carbonization process specific surface area and specific pore volume of carbonized product decreased with the increase of carbonization temperature and time. They were proportional to activation temperature and time up to the specific temperature and time in activation process. In carbonization process the increase of heating rate gave negative effect to the properties. The properties of activated product, on the contrary, increased with the heating rate in carbonization process. The properties of activated carbon manufactured with the resin exchanged with divalent cations were lower than those with raw resin.

• Journal of the Korean Magnetics Society
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• v.11 no.1
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• pp.26-31
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• 2001

The effect of MoO$_3$ addition on the permeability of Mn-Zn ferrites was studied. 600 ppm, 800 ppm and 1,000 ppm of MoO$_3$ were added to the main composition after calcination. Ferrite cores were sintered at 135$0^{\circ}C$ for 3hrs, followed by cooling according to the equilibrium oxygen concentration. The initial permeability was about 8,000 with heating rate 5$^{\circ}C$/min for 3hrs without MoO$_3$ addition. When 600 ppm and 800 ppm of MoO$_3$ were added, the initial permeabilities, 13,200 and 13,550 were obtained, respectively. However, the sample with 1,000 ppm MoO$_3$ showed lower permeabilities because of abnormal grain growth. At the heating rate 1$0^{\circ}C$/min, the ferrite cores with 1,000 ppm MoO$_3$ demonstrated the highest initial permeability greater than 15,000, without exaggerated grain growth.

• Resources Recycling
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• v.8 no.4
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• pp.3-10
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• 1999

An experimental study for manufacturing lightweight aggregates from sewage sludge ash of sewage treatment facilities was carned out in senses of sludge disposal and utilization. In case of SA alone, aggregates with S.G. 1.67 was obtained at sintering temperature of $1250^{\circ}C$, and heating rate affects little to volume expansion rate and volume expansion rate was decreased more or less by heating time. In case of adding 10 wt% of RFCC to SA, lightweight aggregates with S.G. 1.07 was obtained and volume expansion rate was increased by heating time. The optimum adding amounts of RFCC to manufacture lightweight aggregates was 10wt% and the condition that shows maximum volume expansion rate was $20^{\circ}C/min$ of heating rate, $1250^{\circ}C$ of sintering temperature and 50 mmutes of heating time. According to adding amounts of RFCC, Compressive strength of sample results in 30 wt% RFCC>SA>20 wt% RFCC>10 wt% RFCC.

• Korean Journal of Materials Research
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• v.8 no.4
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• pp.299-303
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• 1998

We examined, using thermoanalytical methods, the effects of $2000^{\circ}C$ heat-treated graphite powders and heating rate of cure after impregnation on the thermal stability and carbon yield of furfuryl alcohol, which is frequently used not only as an impregnant but also as a matrix precursor for carbon fiber-reinforced carbon composites. It was founded that the addition of 30wt% graphite powders to furfuryl alcohol and the heating rate of $35^{\circ}C$/min showed the highest thermal stability of furfuryl alcohol/graphite powder mixture. The carbon yield above $1000^{\circ}C$ was enhanced more than 10% in comparison with the absence of graphite powders. It would be expected that this result can contribute to some extent to reduce the repeating number of processing cycle (carbonization-impregnation-cure-re-carbonization) required to densify a carbonaceous composite.