• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.271-274
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• 2001

최근 압전성 및 유전성, 비선형 광학전도성 등과 같은 특성을 갖는 전기전자 및 광기능성 고분자에 대한 연구가 많이 이루어지고 있다[1-2]. 그 중에서 압전 및 초전성을 나타내는 대표적 유기 고분자인 poly(vinylidene fluoride)(PVDF)의 경우 압전성을 향상시키기 위하여 vinylidene. fluoride(VDF)나 vinyl fluoride(VF), trifluoroethylene(TrFE) 등과 공중합시킨 고분자들에 대한 연구가 활발히 진행되어 왔다[3-4]. (중략)

• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.611-616
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• 2011

In the study, annealing temperature was optimized by comparing with avrami crystallization rate and constant (k) using non-oriented PLA film as a base film. Crystallization rate constant of PLA film was 1.64, 1.68, and 1.26 at $120^{\circ}C$, $130^{\circ}C$, and $140^{\circ}C$, respectively. Annealing temperature was mainly affected on the surface properties such as rougnness (Ra) and kinetic friction coefficient (${\mu}_k$). Roughness of PLA film was 0.006 ${\mu}m$ at $80^{\circ}C$ and increased to 0.009 ${\mu}m$ 0.015 ${\mu}m$, 0.027 ${\mu}m$, and 0.029 ${\mu}m$ at $110^{\circ}C$, $120^{\circ}C$, $130^{\circ}C$ and $140^{\circ}C$, respectively. Kinetic friction coefficient decreased 0.45 to 0.43, 0.33, 0.31, 0.27 as annealing temperature was at $80^{\circ}C$, $110^{\circ}C$, $120^{\circ}C$, $130^{\circ}C$, and $140^{\circ}C$, respectivly. In addition, rate constant (k) was 0.58, 0.46, and 0.39 with adding 1 wt%, 3 wt%, and 5 wt% talc, respectively.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.169-175
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• 2012

In the study, the effects of $130{\sim}150^{\circ}C$ annealing condition and 1~10 wt% isopropylphenyl diphenyl phosphate (IPPP) on crystallization behavior and flame retardancy of a full name (PLA) film were determined. The crystallization kinetics of PLA films with adding 1, 5, and 10 wt% IPPP at $140^{\circ}C$ were higher than those at 130 and $150^{\circ}C$. The average crystallinity and crystallite size of PLA film with 1 wt% IPPP were 21.3% and 24.8 nm, respectively. With an increasing IPPP content, the crystallinity of PLA film increased and the crystallite size decreased. The burning rate lowered with an increasing IPPP content as well.

• Journal of Ceramic Processing Research
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• v.20 no.1
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• pp.63-68
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• 2019

We investigated the effects of Al2O3 addition on (1-x)Li2B4O7-xAl2O3 (LBAO; x = 0, 0.005, 0.01, 0.05, 0.07, and 0.1) glasses. The glasses were synthesized by a conventional melt-quench method. Structural transformations of the LBAO glasses were assessed via X-ray diffraction analysis. Estimations of ΔT, KGS = (Tc-Tg)/(Tm-Tc), activation energy, and the Avrami parameter were performed using differential thermal analysis and differential scanning calorimetry. An interpretation of non-isothermal kinetics of the crystallization process is presented using the modified Ozawa equation. The activation energy E increased from 3.3 to 3.5 eV for the LBAO (x < 0.01) glasses whereas those of the LBAO (x > 0.05) glasses slightly increased from 3.75 to 4.05 eV. The exponent n was estimated to be 3.9 ± 0.1 for the LBAO (x < 0.01) glasses and 3.2 ± 0.02 for the LBAO (x > 0.05) glasses. Microstructural characterization of the glassy and crystalline phases using atomic force microscopy was investigated. The effects of Al2O3 on the LBAO glasses include a decreased nucleation rate in the crystallization process and a significantly reduced crystal size.

• Journal of the Korean Society for Heat Treatment
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• v.8 no.3
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• pp.236-243
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• 1995

Since amorphous alloys have been known to have better mechanical and chemical properties than crystalline alloys of the same composition, a great number of studies on the formation of Al-based amorphous alloys have been carried out actively. However, little has been obtained about the effect of Rare-Earth metal and Transition metal addition on amorphous phase formed by melt spinning method. This study included fabrication of amorphous alloy $Al_{85}Ce_5Ni_{10}$ by melt spinning methods and DTA, XRD, TEM analysis to determine crystalization behavoir. Annealing treatments were carried out in Ar atmosphere under isothermal and nonisothermal conditions. The diffraction pattern of non-heated ribbons showed broad form characteristic of glass metallic alloy. The crystallization of amorphous $Al_{85}Ce_5Ni_{10}$ takes place eutedtoidly by homogeneous formation of Al and MS-1, followed by precipitation of the $Al_{11}Ce_3$ and later $MS-1{\rightarrow}Al_3Ni$ transformation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.4
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• pp.261-266
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• 2010

In this paper, we report the changes of electrical, structural and optical characteristics in $Ge_2Sb_2Te_5$ thin films according to an increase of Si content. The Si-doped $Ge_2Sb_2Te_5$ thin films were prepared by rf-magnetron co-sputtering method. Isothermal annealing was carried out at $N_2$ atmosphere. The crystallization speed (v) of amorphous thin films was evaluated by detecting the reflection response signals using a nano-pulse scanner (wavelength = 658 nm) with illumination power of 1~17 mW and pulse duration of 10~460 ns. Structural phase changes were evaluated by XRD, and the optical transmittance was measured in the wavelength range of 300~3000 nm using UV-vis-NIR spectrophotometer. The sheet resistance (RS) of the thin films was measured using 4 point probe. Conclusivlely, the v-value decreased with an increase of Si content, while the RS-values of both crystalline and amorphous phases were increased. In particular, fcc-to-hexagonal transition was suppressed by the added Si atoms.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.143-146
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• 1996

In (GeTe)$_{100-x}$(Sb$_2$Te$_3$)$_{x}$(x=33.5, 50, 66.5, 80 at.%) thin films, the optical properties of amorphous and crystalline thin film, XRD were studied. Also, the application for the phase change optical recording materials with the high stability and rapid erasing ability were studied. In the (GeTe)$_{100-x}$(Sb$_2$Te$_{3}$)$_{x}$ the transmittance was decreased with the increase of x. In all thin films, the transmittance was decreased and the reflectance was increased by annealing and particularly, the reflectance before and after annealing showed the large reflectance ratio. The XRD pattern, it was confined that these change of optical properties was due to the crystallization of amorphous thin films. The reflectance change was investigated using isothermal annealing condition.ion.ion.

• Polymer(Korea)
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• v.29 no.6
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• pp.605-612
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• 2005

This study investigates the isothermal crystallization behaviors of polypropylene-polyethylene-(1-butene) terpolymer and the adiabatically expanded polyolefin structured foams. For this purpose, butane gas was used as a physical blowing agent. Avrami equation has been used to interpret theoretically the experimental results obtained by either DSC or polarized optical microscope. It is believed that elongation induced crystallization occurring during the adiabatic expansion process has resulted in an increase in crystallization rate, eventually leading to a faster growth rate of spherulites and an increase in the nucleation density. An analysis of the foam by SEM images showed that the structure of foam is uniform (below diameter 30 $\mu$m closed cell) In addition, the thermal conductivity and the compressive strength of the polyolefin structured foams was measured. The thermal conductivity of foamed resin with excellent insulation characteristics is reduced compared with unfoamed resin. The compressive strength is decreased with increase in the expansion ratio.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.2017-2020
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• 2009

Three complexes, [bis(L-, D- and DL-alaninato)(diaqua)]nickel(II) di-hydrate, were prepared and characterized by X-ray crystallography, gas chromatography, UV-Visible spectroscopy and isothermal calorimetry. Small deviations from the 50:50 distribution of the enantiomers assigned to chiral preferences of the ligands in the complexes were observed. The surprising and unexpected results indicate that complexing alanine with nickel(II) ion alters the racemization rates of D and L isomers of the amino acid. The precipitated complex due to change in pH resulted in preferential precipitation of one isomer with respect to the other. It has been observed that this alternation is ogmented by the long time span which would result in preferential protein forming from the L-isomer. Although the results are bizarre and perplexing, they are fascinating and sound scientifically.

• Journal of the Mineralogical Society of Korea
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• v.9 no.2
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• pp.93-101
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• 1996

Behavior of platinum group elements during crystallization within ore magma is of interest. In this study platinum is selected and its mineralogical and geochemical behavior in the presence of antimony and tellurium is investigated at 600$^{\circ}C$. High purity Pt, Sb, and Te are used as starting material and silica quartz tubings are as container. Rection products have been examined by use of ore microscope, X-ray diffractometer, electron microprobe analyser and micro-indentation hardness tester. stable phases at 600$^{\circ}C$ are platinum (Pt), Pt5Sb, Pt3Sb, PtSb, stumpflite (PtSb), geversite (PtSb), PtTe, Pt3Te4, Pt2Te3, moncheite (PtTe2), tellurantimony (Sb2Te3), and antimony (Sb). Geversite is the mineral showing the most significant extent of solid solution by up to 27 at% between Sb and Te elements. Isothermal section of 600$^{\circ}C$ is established in this study. It is noted that platinum cannot coexists with stumpflite or geversite under equilibrium condition, and stumpflite composition in equilibrium with geversite may be used as geothermometer.