• Journal of the Korean Wood Science and Technology
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• v.44 no.1
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• pp.96-105
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• 2016

This study investigated thermal properties and activation energy ($E_a$) of torrefied oak wood powders treated with various torrefaction times (0, 5, 7.5, 10 min) by using non-isothermal thermogravimetric analysis at heating rates of 10, 20, $40^{\circ}C/min$ to check the feasibility of rapidly torrefied oak wood powders as a fuel. As the torrefaction time increases, onset of thermal decomposition temperature, lignin content, and the amount of final residue of torrefied oak wood powders were accordingly increased with reduced hemicellulose content. $E_a$ was determined by using Friedman and Kissinger models and respective R-square values were over 0.9 meaning very good availability of calculated $E_a$ values. The $E_a$ values of the samples were decreased with the increase of torrefaction time and the lowest $E_a$ value ob served in the torrefied oak wood powders treated for 7.5 min showed high feasibility of rapidly torrefied oak wood powder as a biomass-solid refuse fuel.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.235-236
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• 2009

금속 아세테이프가 금속으로 열분해하는 반응을 이용하여 템플레이트 안에 잘 정렬된 금속 나노 구조물을 얻는 것은 센서 (sensor), 분리 막(separation), 저장 장치(storage), 에너지 전환 장치 (energy conversion)에 응용이 가능하다. 실버 아세테이트와 팔라듐 아세테이트에서 순수 실버와 팔라듐 나노 구조의 제조 및 형태의 차이를 밝히는 것을 목적으로 나노 입자의 크기와 활성화 에너지가 이에 영향을 주는 것으로 확인할 수 있었다. 금속 나노 구조의 확인 및 나노입자의 크기와 활성화 에너지를 분석 관찰하기 위해 DSC, TG, XRD, FE-SEM 등을 이용하였다.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.568-573
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• 2008

Kinetic tests on pyrolysis of waste fishing net [WFN; nylon-6], waste ship lubricating oil [WSLO] and their mixture were carried out by thermogravimetric analysis (TGA) with heating rate of 0.5, 1.0, and $2.0^{\circ}C/min$. Pyrolysis of waste fishing net started at $300^{\circ}C$, and the main region of decomposition temperature was between 360 and $440^{\circ}C$ at each heating rate. Decomposition temperature of the mixture of WFN and WSLO was lower than that of WFN and WSLO, and the shape of thermogravimetic graph of mixture was different as well. The corresponding kinetic parameters including activation energy and pre-exponential factor were determined by differential method over the degree of conversions. The values of activation energies for the mixture of WFN and WSLO were between 98 and 427 kJ/mol as the conversion increased from 5% to 95%. Tubing reactor was used to analysis of pyrolyzed oil at $440^{\circ}C$ for 80 min. The selectivity of specific hydrocarbons was not detected and the carbon number distribution of the pyrolyzed oil was below $C_{22}$.

• Polymer(Korea)
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• v.29 no.1
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• pp.64-68
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• 2005

To recycle collected high-impact polystyrene (HIPS) wastes as liquid fuel, depolymerization characteristics of HIPS by pyrolysis was studied. The effects of temperature and time on the pyrolysis of HIPS were investigated. The depolymerization temperature and activation energy of HIPS pyrolysis increased with increasing heating rate. In general, conversion and liquid yield gradually increased with pyrolysis temperature and pyrolysis time. Each liquid product formed during pyrolysis was classified into gasoline, kerosene, light oil and heavy oil according to the distillation temperature based on the petroleum product quality standard of Korea Petroleum Quality Inspection Institute. As a result, the amount of liquid products produced during HIPS pyrolysis was in the order of gasoline》heavy oil〉kerosene〉light oil. Especially 51${\pm}$6 wt% of HIPS treated was obtained as gasoline.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.110-115
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• 2010

The experiment was designed to compare pyrolysis kinetics of two different classes of imported coal. The pyrolysis behaviors of the coals were first observed with thermogravimetric analyzer(TGA). The kinetic analysis was further done based on a new distributed activation energy model(New DAEM). During the analysis, weight loss curves measured at three different heating rates were used to obtain the activation energy distribution function curve f(E) of a given coal sample where a mean activation energy is determined by its peak. The results show a significant difference in the mean activation energy between two coals for the pyrolytic reaction. The prediction of a chemical percolation devolatilization(CPD) model where the kinetics obtained from the New DAEM method were incorporated is in much closer agreement with an experimental data of TGA particularly for the bituminous coal.

• Composites Research
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• v.35 no.4
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• pp.288-297
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• 2022

This study investigated the effect of addition of zirconia(zirconium oxide) powder on the curing behavior of phenolic resins. The heating rate controlled curing and isothermal curing behaviors of the phenol resin according to the content of the zirconia powder were analyzed. The viscosity and thermal decomposition characteristics of the phenolic resin with the zirconia content were also examind. From the DSC analysis, the degree of cure and the rate of cure were obtained. Finally, the activation energy for the cure reaction were calculated from the DSC data of the zirconia added phenolic resin. As a found, the higher the zirconia content, the longer the curing was delayed and the greater the activation energy required for curing. Additionally, the TGA result that as the content of zirconia increased, less weight loss was observed. The surface tackiness of the Carbon/Phenol prepreg was partially changed according to the zirconia content, but had no significant effect.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.104-110
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• 2019

The thermal decomposition characteristics of boron-potassium nitrate ($BKNO_3$) were investigated by non-isothermal thermal gravimetric analysis (TGA). Two steps of mass loss were observed in the temperature range between room temperature and $600^{\circ}C$. Kinetic parameters of the thermal decompositions were evaluated from the measured TGA curves using the AKTS Thermokinetics Software. For the first step of mass loss ($220-360^{\circ}C$) corresponding to the thermal decomposition process of the binder (Laminac/Lupersol), the activation energy is in the range of approximately 120-270 kJ/mol when evaluated by Friedman's iso-conversional method, while the value of activation energy varies in the range of approximately 150-400 kJ/mol during the second step process ($360-550^{\circ}C$).

• Journal of the Korean Institute of Gas
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• v.4 no.1 s.9
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• pp.16-25
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• 2000

To estimate the thermal characteristics and toxic parameters on styrene copolymers, We have investigated the activation energy, physical features and generation possibility of toxic material like narcotic gases. The activation energy was 25${\~}$50 Kcal/mol by the Kissinger's and DSC method at high temperature decomposition. It will be good information to estimate the possibility of fire occurrence. From calculations of FED, the values of $LC_{50}$ for PS, SAN and ABS were checked as 8,580, 265 and 308 $mg/m^3$ The mechanisms of thermal decomposition were mainly estimated by main chain scission, not by side group on FT-IR analysis.

• Korean Journal of Food Science and Technology
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• v.12 no.3
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• pp.209-215
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• 1980

Proteases from papaya latex were partially purified by ammonium sulfate precipitation and separated into two fractions (Fraction I and II ) by carboxymethyl cellelose column chromatography. Each fraction, mixture of the two fractions, and crude extract of the papaya latex at pH 7.0 were inactivated at the range of $60{\sim}90^{\circ}C$ and thermal properties of the enzymes were investigated. In the thermal inactivation of fraction I, the enthalpy of activation was 89.5 kJ/mol; the entropy of activation, -44.0 J/mol K; the free energy of activation, 104.6 kJ/mol; z-value, $25^{\circ}C$. For fraction II, the enthalpy of activation was 96.5 kJ,/mol; the entropy of activation, -22.0 J/mol K; the free energy of activation, 104.0 kJ/mol; z-value, $23^{\circ}C$. For the mixture of fraction I and II, the enthalpy of activation was 90.9 kJ/mol; the entropy of activation, -38.8 J/mol·K; the free energy of activation, 104.2 kJ/mol; z-value, $24.6^{\circ}C$. For crude extract, the enthalpy of activation was 113.8 kJ/mol; the entropy of activation, 22.0 J/mol·K; the free energy of activation, 106.2 kJ/mol; z-value, $23.2^{\circ}C$. It was indicated that the fraction I was more heat-stable than the fraction II and this suggested that the thermal stability of the proteases in papaya latex is probably due to the fraction I.

• The Korean Journal of Food And Nutrition
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• v.20 no.2
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• pp.120-124
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• 2007

The thermal degradation kinetics of alpha-, gamma- and delta-tocopherols was studied during heating at 100, 150 200 and 250$^{\circ}C$ for 5, 15, 30 and 60 min in the absence of oxygen. The tocopherols were separated by HPLC using a reversed phase ${\mu}$-Bondapak C$_{18}$-column with two kinds of elution solvent system in a gradient mode. The kinetics for degradation of ${\alpha}$-, ${\gamma}$- and ${\delta}$-tocopherols was analyzed as a function of temperatures and times. The degradation of tocopherols was described by the first-order kinetics in the absence of oxygen. The rate of tocopherols degradation was dependent on heating temperatures. The degradation rate constants for ${\alpha}$-, ${\gamma}$ and ${\delta}$-tocopherols showed an increasing trend as the heating temperature increased. The magnitude order of the experimental activation energy was ${\delta}$->${\gamma}$->${\alpha}$-tocopherol.