• 폴리머
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• 제32권4호
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• pp.305-312
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• 2008

A novel TPC-PEG-TPC with active end-groups was obtained from the end-groups of polyethylene glycol (PEG) modified by terephthaloyl chloride (TPC). These active end-groups can link up with a rare earth ion, which is a luminescent center of a rare earth fluorescent complex. Complexes of Eu-PEG with novel ligands (TPC-PEG-PTC) were synthesized by the coordination of the active reactant (as the first ligand) and phenanthroline (as the second ligand) with $Eu^{3+}$.IR, $^1H$-NMR, element analysis, DSC, WAXD, fluorescent spectroscopy, TGA, and SEM were used to characterize the structure and properties of these complexes. The results showed that this type of complex is a heat storage material with the phase change character of polyethylene glycol (PEG) and the luminescent properties of europium. There was no thermal decomposition of the complex of Eu-PEG until $300^{\circ}C$. SEM showed that the complex of Eu-PEG can be dispersed in PE.

• 한국재료학회지
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• 제26권5호
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• pp.287-291
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• 2016

The effect of heat treatment on the microstructure and mechanical properties of cast Ti-6%Al-4%V alloy was investigated. Heat treatment of cast Ti-6Al-4V alloy was conducted by solution treatment at $950^{\circ}C$ for 30 min; this was followed by water quenching and then aging at $550^{\circ}C$ for 1 to 1440 min. The highest hardness of the heat-treated specimens was obtained by solution treatment and subsequent aging for 5 min due to precipitates of fine ${\alpha}$ that formed from retained ${\beta}$ phase. The tensile strength of this alloy increased without dramatic decrease of the ductility due to microstructural refinement resulting from the decomposition of ${\alpha}^{\prime}$ martensite into fine ${\alpha}$ and ${\beta}$ phases, and also due to the fine ${\alpha}$ phase formed from the retained ${\beta}$ phase by aging treatment for 5 min. In addition, this strengthening might be caused by the transformation induced plasticity (TRIP) effect, which is a strain-induced martensite transformation from the retained ${\beta}$ phase during deformation, and which occurs even after aging treatment at $550^{\circ}C$ for 5 min.

• 한국세라믹학회지
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• 제45권5호
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• pp.280-284
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• 2008

In order to investigate residence time effect on the growth of ZrC film, the ZrC films grew with various system total pressure (P) and total flow rate (Q) by low pressure chemical vapor deposition because residence time is function of system total pressure and total flow rate. Thermodynamic calculations predict that the decomposition of source gases ($ZrCl_4$ and $CH_4$) would be low as increasing the residence time. Thermodynamic calculations results were proved by investigating deposition rate with various residence time. Deposition rate decreased with residence time of source gas increased. Besides, depletion effect accelerated diminution of deposition rate at high residence time. On the other hands, the deposition rated was increased as decreasing the residence time because fast moving of intermediate gas species decrease the depletion effect. The crystal structure was not changed with residence time. However, the largest size of faceted grain showed up to specific residence time and the size of grain was decreased whether residence time increase or not.

• 한국환경과학회지
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• 제14권5호
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• pp.513-520
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• 2005

For the destruction of toxic chlorinated organic compounds, this study proposes improved supercritical water oxidation method (multistep oxidation) using sodium nitrate as an oxidizer. This method solves the problems involved in the existing supercritical water oxidation method. Multistep oxidation means that $NaNO_3$ is oxidized to $N_2\;via\;NaNO_2$ and NO. Toxic and hard to destroy organic substances like para-dichlorobenzen(4-DCBz), polychlorinate biphenyl(PCB) ware oxidized to non toxic substances in a condition, in which rapid pressure and temperature rise is restrained as much as possible. 4-dichlorobenzene(4-DCBz) and Polychlorinate biphenyl(PCB) in condition$(450^{\circ}C,\;p_w=0.25g/cm^3,\;30min)$ Was discomposed perfectly.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 디스플레이 광소자분야
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• pp.155-159
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• 2003

The preparation and luminescence characterization of yttrium oxide doped with trivalent europium phosphors by sol-gel method have been investigated. Aqueous metal nitrate solution was mixed with EDTA which was chosen by the most suitable material of sol-gel formation one of appled various chelating agents. we noticed that the samples when are heated with EDTA at a temperature of $100^{\circ}C$ for 1hrs, produced brownish and crisp powders due to condensation reaction on decomposition, dehydration and formation of sol-gel. Hence, when the powder pre-heated was then heated at $1200^{\circ}C$ for 3hrs in atmosphere, the luminescence characterization of resultant $Y_{2}O_{3}:Eu^{3+}$ phosphor was enhanced upto maximum 30% significantly than conventional method through increasing porous region and decreasing particle sizes.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 디스플레이 광소자분야
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• pp.151-154
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• 2003

The synthesis and luminescent properties of trivalent europium activated gadolinium oxide red phosphors by sol-gel process have been investigated. Aqueous metal nitrate solution was mixed with EDTA which was chosen by the most suitable material of sol-gel formation as chelating agents. We noticed that the samples when are heated with EDTA at a temperature of $100^{\circ}C$ for lhrs, produced brownish and crisp powders due to condensation reaction on decomposition, dehydration and formation of sol-gel. Hence, when the powder pre-heated at about $100^{\circ}C$ was then heated at $1200^{\circ}C$ for 3hrs in atmosphere, the luminescence properties of resultant $Gd_{2}O_{3}:Eu^{3+}$ phosphor was measured by SEM, FT-IT and brightness intensity was shown 20% higher than those prepared by conventional method and by other chelating agent.

• 한국디지털건축인테리어학회논문집
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• 제12권4호
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• pp.59-66
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• 2012

This study is interested in identifying the effectiveness of alkali-activated fire protection material compounds including the alkali-activator such as potassium hydroxide, sodium silicate and fly ash as the fire resistant finishing materials. Also, this paper is concerned with change in compressive strength and pore structure of the alkali-activated fire protection material at high temperatures. The testing methods of fire protection materials in high temperature properties are make use of TG-DSC and mercury intrusion porosimetry measurements. This study results show that compressive strength is rapidly degraded depending on a rise of heating temperature. Porosity showed a tendency to increase irrespective of specimen types. This is due to both the outbreak of collapse of gel comprising the cement and a micro crack by heating. However, alkali-activated fire protection material composed of potassium hydroxide, sodium silicate and fly ash has the thermal stability of the slight decrease of compressive strength and porosity at high temperature. These thermal stability is caused by the ceramic binding capacity induced by alkali activation reaction by the reason of the thermal analysis result not showing the decomposition of calcium hydrate.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.351-354
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• 2000

AC impedance of LiM $n_2$ $O_4$ and LiM $g_{0.1}$M $n_{1.9}$ $O_4$ samples have been studied at various temperature with charge-discharge test. AC impedance of LiM $n_2$ $O_4$ measured at -2$0^{\circ}C$, room temperature and 5$0^{\circ}C$ revealed that initial impedance before charge-discharge test was gradually decreased and become small by becoming law temperature. It indicates that the Li ion diffusion and the transfer resistance of the cathode are related to the temperature of cycling. Impedance at high temperature was suddenly increased because Mn dissolution and decomposition of electrolyte had been increased during cycling, compared to impedance at low temperature. Therefore, charge-discharge capacity was suddenly decreased at high but was slowly at low. In LiM $g_{0.1}$M $n_{1.9}$ $O_4$, impedance and capacity were stability at room temperature than there at 5$0^{\circ}C$, too. Initial impedance at 5$0^{\circ}C$ before charge-discharge test was small and impedance was suddenly increased during cycling than that at room temperature.ure.ure.

• 한국추진공학회지
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• 제9권2호
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• pp.25-31
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• 2005

카본-페놀릭 복합재로 제작된 로켓 방화벽이 운전조건 하에서 열-화학적 분해되는 것을 해석하기 위해 (1)의 논문에 기술된 열 및 기체확산을 수반하는 다공 탄성 복합재료의 거동이론을 적용하였다. 해석 대상의 구조 부재는 카울 링이며, 재료 내의 압력, 온도 및 층간 응력이 제시되었다. 특정 조건의 복합재 구조에 대한 해석의 결과는 재료 내의 발생하는 인장응력에 의해 플라이리프트를 나타내는 충간파손을 나타낸다. 해석 결과는 실제 구조의 파손과 모양 및 위치가 일치한다. 이 방법은 플라이리프트와 같은 파손을 피하기 위한 설계에 적용될 수 있다.

• 한국전기전자재료학회논문지
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• 제35권4호
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• pp.359-365
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• 2022

The development of efficient electron donor (or hole-transporting) molecules that can be used in various optoelectronic device fields is highly demanded. In this work, a novel class of triptycene-based three-dimensional (3D) triphenylamine (TI-TPA) derivatives with different end substituents was designed and prepared for transparent electron donor materials. Owing to the rigid 3D triptycene framework, the obtained TI-TPA derivatives had an amorphous morphology with high thermal decomposition temperature. The oxidation potential of these TI-TPA derivatives decreased as the electron donating strength of the end substituent increased. Among TI-TPA derivatives, TI-TPA-OMe exhibited the highest HOMO level (-5.31 eV) which is similar to that of Spiro-OMeTAD (-5.22 eV). In addition, TI-TPA-OMe was found to form a strong charge transfer complex with the triptycene-based acceptor TI-BQ, leading to a new absorption band at around 640 nm. These results can be applied for developing efficient electron donor materials that can mimic the advantages of the spiro-linked structure and TPA units of Spiro-OMeTAD.