• Resources Recycling
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• v.26 no.2
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• pp.25-32
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• 2017

Since the heating values of swine manures were very low at 859~1,075 kcal/kg, it was necessary to convert to carbonization residue by carbonization processes among thermal processes. The most important factor in the carbonization process of swine manure is the carbonization temperature, and it was evaluated the optimal range of carbonization temperature for swine manure in this study by the thermal characteristics and the reaction kinetics. The carbonization of swine manure could be described by the 1st order reaction and Arrhenius equation. The frequency factor (lnA) and the activation energy were estimated to be 3.05~13.08 and 6.94~18.05 kcal/mol, respectively. The range of optimal carbonization temperature range of swine manure was $260{\sim}300^{\circ}C$.

• Composites Research
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• v.35 no.2
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• pp.53-60
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• 2022

This study uses Diglycidyl ether of terephthalylidene-bis-(4-amino-3-methylphenol) (DGETAM), an amine hardener 4,4'-diaminodiphenylethane (DDE) and cationic catalyst N-benzylpyrazinium hexafluoroantimonate (BPH) to make epoxy film. For analysis, ¹H_NMR and FT-IR were used to verify proper synthesis, and the liquid crystallinity of DGETAM was checked using Differntial Scanning Calorimetry and Polarized Optical Microscopy. Thermal conductivity of the sample was measured using Laser Flash Apparatus. Thermal stability as well as thermal conductivity is important when used as a packaging material. Activated energy is the energy needed to generate a response, which can be used to estimate the energy required to maintain physical properties. It was obtained using the Arrhenius equation based on the data measured by isothermal decomposition using Thermogravimetric Analysis. Measurement of the thermal conductivity of epoxy films showed higher thermal conductivity when DDE was used, and it was found that thermal conductivity had an effect on thermal stability, given that it represented an activation energy similar to a film with BPH upon 5% decomposition.

• Elastomers and Composites
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• v.59 no.2
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• pp.73-81
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• 2024

In the field of electronic components, the potting material, which is a part of the electronic circuit package, plays a significant role in protecting circuits from the external environment and reducing signal interference among electronic devices during operation. This significantly affects the reliability of the components. Therefore, the accurate prediction and assessment of the lifespan of a material are of paramount importance in the electronics industry. We conducted an accelerated thermal aging evaluation using the Arrhenius technique on elastic potting material developed in-house, focusing on its insulation, waterproofing, and contraction properties. Through a comprehensive analysis of these properties and their interrelations, we confirmed the primary factors influencing molding material failure, as increased hardness is related to aggregation, adhesion, and post-hardening or thermal-aging-induced contraction. Furthermore, when plotting failure times against temperature, we observed that the hardness, adhesive strength, and water absorption rate were the predominant factors up to 120 ℃. Beyond this temperature, the tensile properties were the primary contributing factors. In contrast, the dielectric constant and loss tangent, which are vital for reducing signal interference in electric devices, exhibited positive changes(decreases) with aging and could be excluded as failure factors. Our findings establish valuable correlations between physical properties and techniques for the accurate prediction of failure time, with broad implications for future product lifespans. This study is particularly advantageous for advancing elastic potting materials to satisfy the stringent requirements of reliable environments.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.142.1-142.1
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• 2016

We present bulk diffusion rates of hydroxide ions in amorphous solid water (ASW) at 135 ~ 160 K. Previous researches showed that the diffusion mechanism of hydroxide is different from one of hydronium ions, and this implies that they have different diffusion rates. In ultra-high vacuum (UHV) chamber, low-energy scattering (LES) was used to measure ion population and temperature-programmed desorption (TPD) was conducted for measuring ASW thicknesses. To determine the diffusion rates, a simple model for $H_2O/NaOH/H_2O$ sandwich films was developed using Fick's second law. The measured surface population of hydroxide ions as a function of time was well fitted to the model, and the rates were well agreed to an Arrhenius equation.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.337-340
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• 1999

The aim of this study is to predict concrete strengths by method of equivalent ages. The method of equivalent ages is to use Arrhenius equation which indicates the influence of curing temperature on the initial hydration ratio in cement. Experimental factors are in this study. The water-cement ratios of concrete mixtures are 0.60, 0.55, 0.50 and 0.45. The curing temperatures within the four chambers are 30, 20, 10 and 5$^{\circ}C$. The test results showed that equivalent age can be used to predict compressive strength of concrete at early ages.

• Journal of the Korean Ceramic Society
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• v.25 no.4
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• pp.415-423
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• 1988

Mixtures of carbon and silica (about 0.46${\mu}{\textrm}{m}$) which was synthesized by the hydrolysis of ethyl silicate, the molar ratio of silica/carbon was fixed as 1/10(weight ratio : 1/2), were nitrided in the temperature range 135$0^{\circ}C$~150$0^{\circ}C$. The phse of the product Si3N4 was $\alpha$ phase and the morphology was hexagnoal prism and the nitridation reaction was completed in 5 hrs at 150$0^{\circ}C$ or 7hrs at 145$0^{\circ}C$. The reaction rate above 150$0^{\circ}C$ was diffusion-controlled, following Jander equation. Activation energy Q was derived from the Arrhenius plot and the value was about 101kcal/mol. Axis ratio of Lattice constants(c/a) was 0.726 and unit volume was $\AA$3, the larger the molar ratio of carbon/Alkoxide was, the smaller the particle size of $\alpha$Si3N4 was.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.4
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• pp.225-230
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• 2002

Experiments on deactivation kinetics of immobilized lipase enzyme from Candida cyl-indracea were performed in stirred bath reactor using rice bran oil as the substrate and temperature as the deactivation parameter. The data were fitted In first order deactivation model. The effect of temperature on deactivation rate was represented by Arrhenius equation. Theoretical equations were developed based on pseudo-steady state approximation and Michaelis -Menten rate expression to predict the time course of conversion due to enzyme deactivation and apparent half-life of the immobilized enzyme activity in PFR and CSTH under constant feed rate polity for no diffusion limitation and diffusion limitation of first order. Stability of enzyme in these continuous reactors was predicted and factors affecting the stability were analyzed.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.403-408
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• 2003

A newly isolated Rhodopseudomonas palustris P4 could decolorize various synthetic dyes containing different chromogenic groups such as azo linkage (Crocein Orange G, New Coccine, Chromotrope FB, Congo Red, Remazol Black B), anthraquinone Reactive blue 2, or indigo Indigo Carmine. Among them, the degradation rate of Black B was studied in detial. Degradation of Black B followed the Arrhenius equation in 25 - $40^{\circ}C$ with an activation energy of 7.79 kcal/mol. Optimum pH was 8. Glucose in the range of 5 - 50g/l did not affect the Black B decolorization. When Black B increased from 25 mg/l to 2000 mg/l, decolorization activity increased almost linearly but the extent of decolorization was constant at about 86% irrespective of dye concentration. Analyses by HPLC revealed that the Black B molecules were partially degraded and some chromogenic intermediates were produced. These results indicate that Rps. palustris P4 has an outstanding capability to degrade various dyes.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.76-83
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• 2002

Mathematically and chemically simplified reaction scheme for n(heptane that simulates autoignitions of the end gases in spark ignition engines has been developed and studied computationally. The five(equation model is described, to predict the essential features of hydrocarbon oxidation. This scheme has been calibrated against autoignition delay times measured in rapid compression machines. The rate constants, activation temperatures, Ta, Arrhenius pre-exponential constants, A, and heats of reaction for stoichiometric nheptane/air has all been optimized. Comparisons between computed and experimental autoignition delay times have validated the present simplified reaction scheme. The influences of heat loss and concentration of chain carrier at the beginning of compression upon autoignition delay times have been computationally investigated.

• Journal of Power System Engineering
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• v.20 no.4
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• pp.38-43
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• 2016

Safety-related equipments of Nuclear Power Plants(NPP) have to perform environmental qualification test in accordance with IEEE-323 standards. However, non-metallic materials replace new one regularly instead of the test because they are considered as consumable parts. In this study, the seven kinds of non-metallic materials are selected and their activation energy was experimentally evaluated with uncertainty analysis by using thermogravimetric analyzer(TGA). In order to obtain activation energy of non-metallic materials, mass difference, temperature raising rate and conversion rate on the specimen are analyzed. It is postulated that the three experiment conditions are important to get a reliable activation energy. This postulate was experimentally confirmed using Arrhenius equation and Flynn-Wall-Ozawa analysis.