• Journal of the Korean Ceramic Society
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• v.48 no.2
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• pp.173-177
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• 2011

Decomposition promoting factors and decomposition mechanism in the zinc decomposition process of waste hard metals which are composed mostly of tungsten carbide and cobalt were evaluated. Zinc volatility amount was suppressed and zinc valatilization pressure was produced in the reaction graphite crucible inside an electric furnace for ZDP. Reaction was done for 2 h at $650^{\circ}C$, which 100 % decomposed the waste hard metals that were over 30 mm thick. As for the separation-decomposition of waste hard metals, zinc melted alloy formed a liquid composed of a mixture of ${\gamma}-{\beta}1$ phase from the cobalt binder layer (reaction interface). The volume of reacted zone was expanded and the waste hard metal layer was decomposed-separated horizontally from the hard metal. Zinc used in the ZDP process was almost completely removed-collected by decantation and volatilization-collection process at $1000^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.17 no.2
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• pp.71-74
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• 1985

In the present study, a tentative mechanism for the decomposition of the hydroperoxide formed during the thermal oxidation of an edible soybean oil was proposed. The soybean oil was thermally oxidized at $120^{\circ}C$ for 7 hrs with air injection at a rate of 120 ml/min. Through kinetic studies of the decomposition process based on the tentative mechanism and the actual experimental data obtained from the hydroperoxide decomposition at 100, 120, 150 and $180^{\circ}C$, it was found that the reaction order of the hydroperoxide decomposition in these conditions was of first order. It was also estimated that the dissociation energy for the hydroperoxide in the same conditions was 15.876 kcal/g. mol.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.157-159
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• 2015

In this study, $CF_4$ decomposition was experimentally investigated in a high temperature flow reactor. Effects of temperature, reactant composition and concentration, and residence time on its decomposition into other stable species were analyzed. Then the results were compared to numerical results obtained using Chemkin Plug Flow Reactor model with Princeton Chemistry. As a preliminary result higher decomposition rate is obtained for higher reactor temperature and long residence time when proper reactants are supplied.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.4
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• pp.23-30
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• 1999

The thermal decomposition of phase stabilized ammonium nitrate(PSAN) was studied by means of thermogravimetric analysis(TGA). In this study, potassium nitrate and zinc oxide were used as the phase stabilizers in the range of contents from 0 wt.% to 8 wt.%. The kinetics and mechanism for the decomposition were evaluated using integral methods. It was found that the thermal kinetic parameters such as activation energy(I) and frequency factor(A) increase with the increase of the stabilizer contents, and the mechanism of decomposition also changes.

• Polymer(Korea)
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• v.25 no.6
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• pp.866-875
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• 2001

In this work, thermal decomposition mechanism based on kinetic parameters and thermal stability of carbon fiber-reinforced carbon matrix composites (C/C composites), have been studied under high temperature oxidative conditions with addition of tetra-ethylorthosilicate (TEOS) as an oxidation inhibitor. Thermogravimetric analysis (TGA) was executed to evaluate the thermal decomposition mechanism and thermal stability of C/C composites in the temperature range of 30 ～ $850^{\circ}C$. As a result, the kinetic parameters of the composites impregnated with TEOS, i.e., activation energy for thermal decomposition ($E_d$), order of reaction (n) , and pre-exponential factor (A) were evaluated as 136 kJ/mol, 0, and 2.3$\times$$10^9s^{-1}$, respectively. Especially, the IPDT and $E_d$ of C/C composites impregnated with TEOS were improved largely compared with the composites impregnated without TEOS, due to the formation of $SiO_2$ on composite surfaces, resulting in interrupting the oxygen attack to carbon active site in the composites.

• Journal of the Korean Chemical Society
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• v.37 no.2
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• pp.199-205
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• 1993

The decomposition of hydrogen peroxide by copper-amines complexes was studied in the pH range of 7.3∼11.3 by measuring the rate of the decreasing concentration of $H_2O_2$. Decomposition rate of hydrogen peroxide increased with increasing pH, and then decreased with increasing pH successively. The mechanism for this type of reaction involves the formation of peroxo complexes in the rate-determining step preceding deprotonation of hydrogen peroxide and copper-amines complexes.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.1
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• pp.87-94
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• 2001

In multibody dynamics, differential and algebraic equations which can satisfy both equation of motion and kinematic constraint equation should be solved. To solve this equation, coordinate partitioning method and constraint stabilization method are commonly used. The coordinate partitioning method divides the coordinate into independent and dependent coordinates. The most typical coordinate partitioning method arc LU decomposition, QR decomposition, projection method and SVD(sigular value decomposition).The objective of this research is to find a efficient coordinate partitioning method in flexible multibody systems and a hybrid decomposition algorithm which employs both LU and projection methods is proposed. The accuracy of the solution algorithm is checked with a slider-crank mechanism.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2483-2488
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• 2012

The X-ray line broadening technique was used to calculate the grain size of MgO at 1023, 1123, 1223 K respectively either in $CO_2$ or during the thermal decomposition of magnesites in air as well as in vacuum. By referring to the conventional grain growth equation, $D^n=kt$, the activation energy and pre-exponential factor for the process in air are gained as 125.8 kJ/mol and $1.56{\times}10^8\;nm^4/s$, respectively. Ranman spectroscopy was employed to study the surface structure of MgO obtained during calcination of magnesite, by which the mechanism of grain growth was analyzed and discussed. It is suggested that a kind of highly reactive MgO is produced during the thermal decomposition of magnesites, which is exactly the reason why the activation energy of the grain growth during the thermal decomposition of magnesite is lower than that of bulk diffusion or surface diffusion.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2385-2391
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• 2018

This paper is devoted to detecting decomposition characteristics of Iodotrifluoromethane ($CF_3I$) under alternating current (AC) discharges or load current interruptions. The decomposition products are measured utilizing chromatography-mass spectroscopy. It is found that less than 1% $CF_3I$ gas decomposed after several interruptions at load current of 200 A or hundred times of AC discharges. However, under interruptions at a current of 400 A, more than 95% $CF_3I$ gas decomposed into carbon tetrafluoride ($CF_4$) and hexafluoroethane ($C_2F_6$). The equilibrium compositions based on Gibbs free energy minimization of $CF_3I$ was calculated to explain the decomposition mechanism.

• Tribology and Lubricants
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• v.18 no.6
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• pp.396-401
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• 2002

ln this paper, the fuction of molybdenum dialkyl dithiophosphate (MoDTP) as an oxidation inhibitor of mineral oils was investigated and compared with 2,6-Di-tert-Butyl-4-Methylphenol (DBMP). Oxidation tests were conducted using an oxygen absorption apparatus. MoDTP showed anti-oxidation property, and length of induction time prolonged by increasing MoDTP concentration. However the induction time of DBMP was longer than those of MoDTP. The anti-oxidation property of MoDTP was found to be inferior to that of DBMP The capability of hydroperoxide decomposition ability with MoDTP was much greater than that with DBMP. However the rate constant of radical scavenging with MoDTP was much better than that with DBMP. It was found that the performance of MoDTP is exellent with respect to hydroperoxide decomposition but it is susceptible to chemical decomposition. From the fact that formation of phenol was observed when MoDTP was added to hexane solution of cumene hydroperoxide (CHPO), it is indicated that the decomposition of hydroperoxide with MoDTP occurs by means of ionic mechanism.