• BMB Reports
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• v.38 no.5
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• pp.533-538
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• 2005

The kinetics of thermal dissociation of superoxide dismutase (SOD) was studied in 0.05 M Tris-HCl buffer at pH 7.4 containing $10^{-4}\;M$ EDTA. The number of conformational locks and contact areas and amino acid residues of dimers of SOD were obtained by kinetic analysis and biochemical calculation. The cleavage bonds between dimers of SOD during thermal dissociation and type of interactions between specific amino acid residues were also simulated. Two identical contact areas between two subunits were identified. Cleavage of these contact areas resulted in dissociation of the subunits, with destruction of the active centers, and thus, lost of activity. It is suggested that the contact areas interact with active centers by conformational changes involving secondary structural elements.

• Korean Journal of Materials Research
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• v.26 no.4
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• pp.182-186
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• 2016

Zircon, having excellent thermal, chemical, and mechanical properties, is utilized in refractory materials, electronic materials, chemical machines, structural materials, etc. However, zircon generally shows thermal dissociation to zirconia($ZrO_2$) and silica($SiO_2$) around the sintering temperature of $1540^{\circ}C$, and when zircon particles are small and impurities are present, thermal dissociation is known to occur at around $1100^{\circ}C$. This reduces the mechanical properties of $ZrSiO_4$. In this research, the effect of adding $SiO_2$ and 3Y-TZP to $ZrSiO_4$ has been studied in order to suppress dissociation and improve the mechanical properties. Addition of $SiO_2$ suppressed the dissociation of $ZrSiO_4$ at lower temperatures. It also enabled optimum packing between the particles, resulting in a dense microstructure and good mechanical properties. When 3Y-TZP was added, recombination with the dissociated $SiO_2$ resulted in good mechanical properties by suppressing the generation of pores and the densification of the microstructure.

• Bulletin of the Korean Chemical Society
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• v.19 no.8
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• pp.822-824
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• 1998

The simple and convenient measurement of the dissociation constant of an indicator, thymol blue, was achieved by using a portable diode-laser/fiber-optic thermal lensing spectroscopy, which consisted of a visible diode laser, a photodiode, and an optical fiber. It gives comparable results to the cited value obtained from a conventional UV/VIS spectroscopy.

• Bulletin of the Korean Chemical Society
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• v.12 no.4
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• pp.397-403
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• 1991

Dissociation of a highly excited diatomic molecule in the Ar + Ar…$O_2$ and Ar + $O_2$ collisions is studied using trajectory dynamics procedures in the collision energy range of 0.050 to 1.0 eV. Between 0.050 and 0.2 eV, dissociation probabilities are very large for the complexed system compared to the uncomplexed system. This efficient dissociation of $O_2$ in Ar…$O_2$ is attributed to the ready flow of energy from the incident atom to the large-amplitude vibrational motion of the excited O2 via the van der Waals bond. Thermal-averaged dissociation probabilites of $O_2$ in Ar + Ar…$O_2$ near room temperature are nearly two orders of magnitude larger than those of $O_2$ in Ar + $O_2$.

• Korean Journal of Materials Research
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• v.21 no.4
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• pp.220-224
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• 2011

Zircon has excellent thermal, chemical, and mechanical properties, but it is hard to make a dense sintered product because of dissociation during the sintering process. This study analyzes how the addition of $SiO_2$ and $Al_2O_3$ affects the mechanical properties of sintered zircon, particularly in regards to reducing the thermal dissociation and improving the mechanical properties of $ZrSiO_4$. Zircon specimens containing different amounts of $SiO_2$ and $Al_2O_3$ were prepared and sintered to observe how the mechanical properties of $ZrSiO_4$ changed according to the differing amount of $SiO_2$ and $Al_2O_3$. The $ZrSiO_4$ that was used for the starting material was ground by ball mill to an average particle size of 3 ${\mu}m$. The $SiO_2$ and $Al_2O_3$ that was used for additives were ground to an average particle size of 3 ${\mu}m$ and 0.5 ${\mu}m$, respectively. Adding $SiO_2$ resulted in transformation in the liquid phase at high temperatures, which had little effect on suppressing the thermal dissociation but enhanced the mechanical properties of $ZrSiO_4$. When $Al_2O_3$ was added, the mechanical properties of $ZrSiO_4$ decreased due to the formation of pores and abnormal grains in the microstructure of the sintered zircon.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.10
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• pp.1155-1162
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• 2004

This paper is the forth paper of several companion papers which compare the method of Air-Fuel ratio determination. In the previous work, various AFR calculations were performed for various fuels and the results were compared with each other. The comparison, however, were limited to numerical value and estimation of each equation or method was insufficient. In this paper, the overall estimation of the methods was attempted. Also, the method of trouble shooting of instrumentation was presented. Through the estimation of methods, it is concluded that the Eltinge method contains inherently the most perfect thermal dissociation model as far as the exhaust composition is concerned; therefore, this might be regarded as the most general equation of AFR determination among the existing ones. The others might be considered as approximate form. In addition, the mal-distribution factor in Eltinge method is qualitatively equivalent to thermal dissociation chemical equilibrium constant K. Lastly, it is illustrated that all instrumentation error, including the sampling line leakage, can be easily detected through the analyzing the exhaust component on the Eltinge chart.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.128-130
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• 2001

In this study, we investigate the deposition characteristics of merocyanine dye(MD) Langmuir-Blodgett(LB) film using quartz crystal microbalance (QCM). The MD optical system mixed with fatty acid was fabricated using LB method. And their optical characteristics were investigated using UV spectroscopy. The optical behavior of MD LB film was investigated asto thermal treatment. The resonant frequency and admittance was measured during dissociation of J-aggregate of MD LB film. As a result, it has been suggested that the J-aggregate dissociation in MD LB film by thermal treatment give rise to transformation of oscillation characteristics of quartz crystal.

• Journal of the Korean Vacuum Society
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• v.2 no.4
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• pp.404-409
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• 1993

Adorption of nitric oxide on the Pt(III) surface sputtered by Ar-ion has been studied using thermal desorption spectroscopy and Auger electron spectroscopy. Ar-ion sputtering creates a precursor state of ($NO\beta$ stage) adsorbe dat defect sites. The precursor state is characterized by the terminal bent species . At low coverge mos 샐 adsorbed NO dissociates . And as increasing the coverage, the fraction of dissociation remains about 80%.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.4
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• pp.371-381
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• 2004

Numerical simulation of $CO_2$ addition effects to fuel and oxidizer streams on flame structure has been conducted with detailed chemistry in H$_2$-O$_2$ diffusion flames of a counterflow configuration. An artificial species, which displaces added $CO_2$ in the fuel- and oxidizer-sides and has the same thermochemical, transport, and radiation properties to that of added $CO_2$, is introduced to extract pure chemical effects in flame structure. Chemical effects due to thermal dissociation of added $CO_2$ causes the reduction flame temperature in addition to some thermal effects. The reason why flame temperature due to chemical effects is larger in cases of $CO_2$ addition to oxidizer stream is well explained though a defined characteristic strain rate. The produced CO is responsible for the reaction, $CO_2$＋H=CO＋OH and takes its origin from chemical effects due to thermal dissociation. It is also found that the behavior of produced CO mole fraction is closely related to added $CO_2$ mole fraction, maximum H mole fraction and its position, and maximum flame temperature and its position.

• Proceedings of the Korean Vacuum Society Conference
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• 1995.02a
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• pp.113-113
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• 1995

The adsorpption and decompposition of NO on a stepped ppt(111) surface have been studied using thermal desorpption sppectroscoppy and Auger electron sppectroscoppy. NO adsorbs molecularly in two different states of the terrace and the stepp, which are distinguishable in thermal desorpption sppectra. NO dissociates via a bent sppecies at the stepp sites on the basis of vibrational sppectrum data repported ppreviously. The dissociation of NO is activation pprocess : the activation energy is estimated to be about 2 kcal/mol. Increase in the NO dissociation with adsorpption tempperature is expplained by a pprocess controlled by different of the dissociated atomic nitrogen from the stepp to the terrace of the surface. In addition to No and N2, the desorpption ppeak of N2O is observed. We conclude that the formation of N2O is attributed to surface reaction of No and N adsorbed on the surface.