• Journal of the Korean Ceramic Society
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• v.35 no.10
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• pp.1061-1069
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• 1998

The thermal instability of Al2TiO5 Ceramics was contrlled by solid solution with MgO SiO2 and ZrO2 through electrofusion in an arc furnace. The thermal expansion properties of Al2TiO5 composites show the hysteresis due to the strong anisotropy of The crystal axes of these material. These phenomena are ex-plained by the opening and closing of microcracks. The difference in microcracking temperatures e.g 587.6(ATG2), 405.9(ATG3) and 519.7$^{\circ}C$(ATG4) is caused by the difference in grain size and stabilizer type. The thermal shock behaviour under cyclic conditions between 750-1400-75$0^{\circ}C$ show no change in mi-crostructure and phase assemblage for all three stabilized specimens. After the thermal loading test at 110$0^{\circ}C$ for 100hrs. ATG1 and ATG2 materials decomposes completely to its components corundum and ru-tile in both cases. However with approximatelly 20% retention of the Al2TiO5 Thus in order to prevent decomposition of the stabilized material in the critical temperature range 800-130$0^{\circ}C$ it must be traversed within a short period of time.

• 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.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.86-88
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• 2006

The novel linear- (V-LUM) and cross-type macromonomers (C-VUM) of vinyl-terminated bifunctional polyurethane were synthesized and applied to the dispersion polymerization of styrene and MMA in ethanol. The existence of the vinyl terminal groups and the grafted macromonomer with styrene and PMMA was verified using 1H NMR and 13C NMR. Monodisperse polystyrene (PS) microspheres were successfully obtained above 15 wt % of macromonomer relative to styrene. The macromonomer can efficiently stabilize higher surface area of the particles compared to a conventional stabilizer, PVP. The grafting ratio of the PS calculated from 1H NMR linearly increased up to 0.048 with 20 wt % of the macromonomer and the high molecular weights (501,300 g/mol) of PS with increased glass transition and enhanced thermal stability were obtained. Furthermore, the stable and monodisperse PMMA microspheres having a weight-average diameter of $5.09{\mu}m$ and a good uniformity of 1.01 were obtained with 20 wt% L-VUM. The molecular weight increased, but the size of the PMMA particles decreased with the macromonomer concentration due to the increased stabilizing effect. The molecular weight of the PMMA was approximately two fold higher than that by a conventional PVP. The L-VUM acts as a reactive stabilizer, which gives polyurethane-grafted PS or PMMA with a high molecular weight. In addition, the XPS result showed that the C-PS (PS using the C-VUM) was anchored with a larger amount of PEG than that of the L-PS (PS using the L-VUM) on the particle surface. Thus, the reaction and stabilizing mechanism of the macromonomers for the formation of PS particles is proposed.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.4
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• pp.61-69
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• 2019

Accelerated aging test for the double base propellant was carried out at three different temperatures (60, 70, and $75^{\circ}C$) for over a year. To evaluate the aging characteristics of the double base propellant, the stabilizer contents and thermal decomposition kinetics were analyzed by using high performance liquid chromatography (HPLC) and AKTS-Thermokinetics software. As a result, stabilizer contents in the double base propellant gradually decreased according to the aging temperature and aging duration. The consumption rate of 2-NDPA in the accelerated aged propellants showed that it was two times faster at $75^{\circ}C$ in compared with ther rate at $70^{\circ}C$. These experimental values were simulated by the SB kinetic model, and it was shown that the two-step model with constant reaction orders n1=1 and n2=0 best describes the process of the stabilizer depletion for the double base propellant.

• Progress in Superconductivity and Cryogenics
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• v.11 no.1
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• pp.25-29
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• 2009

To reduce the power loss in normal state, non-inductively wound high temperature superconducting (HTS) coils are used for fault current limiter (FCL) application. Non-inductively wound coils can be classified into two types: solenoid type and pancake type. These two types have different electrical and thermal and mechanical characteristics due to their winding structure difference. This paper deals with the current limiting characteristics, magnetic field analysis of the two coils. Simulation using finite element method (FEM) was used to analyze the magnetic field distribution and inductance of the coils. Short circuit test using stabilizer-free coated conductor (CC) was also carried out. We can compare the characteristics of the two types of coil by using the data obtained from simulation and short circuit test. We confirmed the feasibility of FCL application by the analysis about the characteristics of non-inductively wound coil using CC.

• The Korean Journal of Food And Nutrition
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• v.22 no.1
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• pp.150-157
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• 2009

The purpose of this study was to analyze the anthocyanin contents of black soybean crude extracts derived using a countercurrent system and to compare the effects of stabilizers(${\beta}-cyclodextrin$, maltodextrin) and sugars(sucrose, maltose) on the color deterioration of the anthocyanin. When the extraction process was kept at 100$^{\circ}C$ for 120$\sim$180 min, only C3G (cyanidin-3-glucoside) was detected in the water extract. The C3G contents in the water extracts acquired at 8$^{\circ}C$, 60$^{\circ}C$, and 80$^{\circ}C$ were 2.38 ppm, 1.73 ppm, and 1.73 ppm, respectively. Sucrose and maltose retarded color deterioration of the crude pigment extract by the countercurrent method with methanol. Finally, the additions of maltodextrin or ${\beta}-cyclodextrin$ did not retard thermal color deterioration of the black soybean crude pigment extract.

• Journal of Sensor Science and Technology
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• v.22 no.1
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• pp.44-48
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• 2013

For a successful commercialization of microbolometer, it is required to develop a robust package including thermal stabilizing mechanism. In order to regulate the temperature within some operating range, thermoelectric cooler is generally used but it's not easy to model the whole package due to the coupled physics nature of thermoelectric cooler. In this paper, SPICE-compatible modeling methodology of a microbolometer package is presented, whose steady-state results matched well with FEM results at the maximum difference of 5.95%. Although the time constant difference was considerable as 15.7%, it can be offset by the quite short simulation time compared to FEM simulation. The developed model was also proven to be useful for designing the thermal stabilizer through parametric and transient analyses under the various working conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.277-277
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• 2010

We present facile chemical route stabilizing dispersion of carboxylated single-Walled carbon nanotubes (SWCNTs) in ZnOsol prepared by using diethanolamine as a stabilizer. The dispersion was stabilized via capping of carboxyl groups on the SWCNT surface by a titania layer. We also demonstrated that the conductivity of the films prepared P3/$TiO_2$/ZnO as enhanced by therml treatment, and the thermal stbility of the film improved hybridization with ZnO sol pristine P3, P3/$SiO_2$ and P3/$TiO_2$ hybrid films.

• Macromolecular Research
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• v.10 no.3
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• pp.168-173
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• 2002

Unstabilized low-density polyethylene (LDPE) films and films formulated with hindered amine light stabilizer (HALS) were exposed to UV-radiation; and the physicochemical changes during photooxidation processes have been investigated using tensile, FTIR spectre-photometric and thermal analytical (DSC) techniques. The dependence of tensile properties (elongation- and stress-at-break), carboxyl index and heat of fusion on UV-irradiation time have been discussed. The use of HALS is found to be effective in maintaining the UV-mechanical properties of the LDPE films. The experimental results showed that there exists no correlation between mechanical properties and carbonyl index, whereas crystallinity correlates well with carbonyl index in unstabilized and stabilized films for irradiation times greater than 100 h. The rate of formation of carbonyl groups is found to be dependent on UV exposure time. Crystallinity of the film samples is strongly influenced by both exposure time and presence of HALS.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.505-509
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• 2013

A low temperature ($65^{\circ}C$) thermal deposition process was developed for depositing a silver coating on thermally sensitive polymeric substrates. This low temperature deposition was achieved by chemical reduction of a silver alkylcarbamate complex with latent reducing agent. The effects of acetol as a latent reducing agent for the silver 2-ethylhexylcarbamate (Ag-EHCB) complex and their blend solutions were investigated in terms of reducing mechanism, and the size and shape of silver nanoparticles (Ag-NPs) as a function of reduced temperature and time, and PVP stabilizer concentration were determined. Low temperature deposition was achieved by combining chemical reduction with thermal heating at $65^{\circ}C$. A range of polymer film, sheet and molding product was coated with silver at thicknesses of 100 nm. The effect of process parameters and heat treatment on the properties of silver coatings was investigated.