• 한국염색가공학회지
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• 제16권4호
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• pp.1-9
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• 2004

In recent, development of nano fiber has been one of the most active subjects in the world. Nano fiber is defined as a ultra fine yarn with a diameter unit of $10-100\times10^{-9}meter$, which is possible to be produced by an electro-spinning technology. In this study, physical characteristics and dyeing properties of nylon 66 nano fiber were investigated. Nylon 66 nano fiber was dyed with levelling type acid dyes. X-ray diffraction method and DSC analysis were used for the measurement of the degree of crystallization. Analysis of amino end groups was also performed in order to examine a relationship between number of amino groups and its dyeing property as well as water absorption behavior. The maximum exhaustion % of dyes and dyeing rate under various dyeing conditions, such as dyeing temperature and pH in dye bath, along with build-up properties for 2 acid dyes were evaluated. It was found that the degree of crystallization of nano fiber was smaller than that of regular fiber, and amino end groups of nano fiber were less than regular fiber. Half dyeing time of nano fiber was shorter than regular fiber because of the bigger specific surface area. Effect of pH on exhaustion % was small in case of nano fiber. Exhaustion of nano fiber increased with higher concentration of dye.

• 상하수도학회지
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• 제21권3호
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• pp.273-278
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• 2007

Modern society has moved from a phosphorus recycling loop, where animal manure and human wastes were spread on farming land to recycle nutrients, to a once-through system, where phosphates are extracted from mined, non-renewable phosphate rock and end up either in landfill(sewage sludge, incinerator ash) or in surface waters. In this research, crystallization of nitrogen and phosphate with natural sources of $Mg^{2+}$ in synthetic water was tested. The operational parameters of pH, mixing time, and the magnesium molar ratio were investigated to find optimal conditions of the MAP precipitation using synthetic wastewater. The removal efficiency of phosphate increased with pH up to 11. By MAP precipitaiton of the synthetic waste water, 94% of the phosphate were eliminated at pH 11. It was found that at least 10 minutes mixing time was required and 20 minutes mixing time was recommended for efficient phosphate removal. High efficiency removal of phosphate was possible when the magnesium molar ratio was 1.0~2.0. The comparative study of different magnesium sources showed that coagulants (PAC) was the more efficient sources than only magnesium. The result showed that 97% of phosphate removal. In conclusion, coagulants (PAC) induced crystallization of struvite and hydroxyapatite was shown to be a technically viable process that could prove cost effective for removing phosphate in wastewater.

• 한국자원리싸이클링학회:학술대회논문집
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• 한국자원리싸이클링학회 2001년도 정기총회 특별강연 및 춘계학술연구발표회(2)
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• pp.129-132
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• 2001

The purpose of this research was to understand possibility of foodwaste treatment by hybrid anaerobic reactor(HAR). The Possibility of methane utility and applicability of hybrid reactor system using foodwaste as substrate was investigated. The maximum loading rate and optimized operational conditions were determined. Hybrid anaerobic reactor was filled with packing material 50% of its total volume between the tube and the outer surface. The packing material used was randomly packed open-pore synthesis activated ceramic(SAC) media as support media for microbial attachment, growth, and chemical stability protected bacteria from effect of organic acid accumulation. In this research, although foodwaste has high concentrations C $l^{[-10]}$ and S $O_{4}$$^{2-}$ concentration the possibility of foodwaste anaerobic treatment was when foodwaste is treated by anaerobic digestion, this study focused on the possibility using C $H_4$ gas made under the anaerobic treatment as an alternative energy source. Other objective of this research is to study struvite formation and crystal forms in anaerobic digester. HAR is used to investigate phosphate crystallization without the addition of chemicals.

• 한국세라믹학회지
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• 제53권2호
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• pp.246-252
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• 2016

Complex designed silica-based ceramic cores were fabricated by ceramic injection molding. Slow heating rate (0.2K/min) for debinding restrained bloating on the surface of ceramic cores. To investigate effect of sintering conditions on mechanical properties of ceramic cores, green bodies were sintered at temperatures in a range from $1150^{\circ}C$ to $1400^{\circ}C$ for various dwelling times (6 h to 48 h). Sintering above $1300^{\circ}C$ for 12 h and dwelling time over 24 h at $1200^{\circ}C$ reduce the flexural strength and increase the linear shrinkage of ceramic cores. Cristobalite, formed by high sintering temperature or long dwelling time, induces reduction of mechanical properties due to its phase transformation, which is accompanied by volume contraction and microcracking. Ceramic core sintered at $1200^{\circ}C$ for 12 h endured wax patterning and shell molding, and was manufactured successfully.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 논문집
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• pp.1-2
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• 2008

Thick films of Carbon fiber were prepared by a heating element of plan shape made in Darin co.. We have investigated surface morphology of the specimen depending on second heat-treatment temperatures. X-ray diffraction patterns of Carbon fiber thick films show that the specimen heat treated below $600^{\circ}C$ was an amorphous phase and the one heat treated above $1100^{\circ}C$ forms a poly-crystallization. Scanning electron microscope(SEM) image of Carbon fiber thick films of the specimen heat treated in between 900 and $1100^{\circ}C$ shows a grain growth. At $1100^{\circ}C$, the specimen stops grain-growing and becomes a poly-crystallization.

• 한국재료학회지
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• 제15권12호
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• pp.802-808
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• 2005

The hydrogen sorption speeds of $Zr_{57}V_{36}Fe_7$ amorphous alloy and its crystallized alloys were evaluated at room temperature $Zr_{57}V_{36}Fe_7$ amorphous alloy was prepared by ball milling. The amorphous alloy was crystallized through two stages. Initially, $\alpha-Zr$ solid solution was appeared from the amorphous phase. Two cubic Laves compounds were precipitated afterwards from the remained amorphous and from excessively saturated solid solution at higher temperature. The hydrogen sorption speed of the partially crystallized alloy was higher than that of amorphous. The enhanced sorption speed of partially crystallized alloy was explained in terms of surface oxygen stability which has been known to retard the activation of amorphous alloys. The retardation could be reduce by crystallization process resulting in the observed increase in sorption property.

• Transactions on Electrical and Electronic Materials
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• 제1권2호
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• pp.28-31
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• 2000

BaTiO$_3$cerameic thin films doped with Mn were manufactured by rf/dc magnetron sputter technique. We have investigated crystal structure, surface morphology and PRCR(positive-temperature coefficient of resistance) characteristics of the specimen depending on second heat-treatment temperature. Second heat treatment of the specimen were performed in the temperature range of 400 to 1350$\^{C}$ X-ray diffraction patterns of BaTiO$_3$ thin films show that the specimen heat treated below 600$\^{C}$ is an amorphous phase and the one heat treated above 1100$\^{C}$ forms a poly-crystallization . In this specimen heat-treated at 1300$\^{C}$, a lattice constant ratio(c/a) was 1.188. Scanning electron microscope(SEM) image of BaTiO$_3$ thin films of the specimen heat treated in between 900 and 1100$\^{C}$ shows a grain growth. At 1100$\^{C}$, the specimen stops grain-growing and becomes a poly-crystallization . A resistivity-temperature characteristics of the specimen depends on the doping concentrations of Mn. A resistivity ratio between the value at room temperature and the one above Curie temperature was 10$^4$ for pure BaTiO$_3$ thin films and 10$\^$5/ fo BaTiO$_3$ : additive 0.127mol% MnO

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.30-33
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• 1997

In this paper, we studied the variation in optical constants of Te-doped G $e_{15}$ /$Sb_{85}$ thin films with 7800$\AA$ diode-laser exposing time and power. The reflectances were increased with the increase of laser exposure time and the laser power in all films. Also, the refractive indices of the films after exposing were higher than those of the as-deposited films. Thus, the fast crystallization was caused by addition to the more Te content at the lower lacer power. It was observed that the surface morphologies of the exposed films are higher than those of the as-deposited films by SEM analysis. Therefore, it is considered that the T $e_{0.5}$(G $e_{15}$ /$Sb_{85}$)$_{99.5}$ thin films will show the high contrast ratio and high SNR and have fast erasing time due to crystallization when these films is applied to optical recording materials.terials.s.

• Advances in nano research
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• 제14권4호
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• pp.355-362
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• 2023

Physical exercise, especially intense exercise and high intensity interval training (HIIT) by trampoline, can lead to muscle injuries. These effects can be reduced with intelligent products made of nanocomposite materials. Most of these nanocomposites are polymers reinforced with silicon dioxide, alumina, and titanium dioxide nanoparticles. This study presents a polymer nanocomposite reinforced with silica. As a result of the rapid reaction between tetraethyl orthosilicate and ammonia in the presence of citric acid and other agents, silica nanostructures were synthesized. By substituting bis (4-amino phenoxy) phenyl-triptycene in N, N-dimethylformamide with potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C, the diamine monomer bis (4-amino phenoxy) phenyl-triptycene is prepared. We synthesized a new polyaromatic (imide) with triptycene unit by sol-gel method from aromatic diamines and dianhydride using pyridine as a condensation reagent in NMP. PI readily dissolves in solvents and forms robust and tough polymer films in situ. The FTIR and NMR techniques were used to determine the effects of SiO₂ on the sol-gel process and the structure of the synthesized nanocomposites. By using a simultaneous thermal analysis (DTA-TG) method, the appropriate thermal operation temperature was also determined. Through SEM analysis, the structure, shape, size, and specific surface area of pores were determined. Analysis of XRD results is used to determine how SiO₂ affects the crystallization of phases and the activation energy of crystallization.

• 한국표면공학회지
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• 제29권6호
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• pp.683-690
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• 1996

In this study, the diffusion barrier properties of $1000 \AA$ thick molybdenum compounds (Mo, Mo-N, $MoSi_2$, Mo-Si-N) were investigated using sheet resistance measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and Rutherford backscattering spectrometry (RBS). Each barrier material was deposited by the dc magnetron sputtering, and annealed at 300-$800^{\circ}C$ for 30min in vacuum. Mo and $MoSi_2$ barrier were failed at low temperature due to Cu diffusion through grain bound-aries and defects of Mo thin film and the reaction of Cu with Si within $MoSi_2$ respectively. A failure temperature could be raised to $650^{\circ}C$-30min in the Mo barrier system and to $700^{\circ}C$-30min in the Mo-silicide system by replacing Mo and $MoSi_2$ with Mo-N and Mo-Si-N, respectively. The crystallization temperature in the Mo-silicide film was raised by the addition of $N_2$. It is considered that not only the N, stuffing effect but also the variation of crystallization temperature affects the reaction of Cu with Si within Mo-silicide. It was found that Mo-Si-N is more effective barrier than Mo, $MoSi_2$, or Mo-N to copper penetration preventing Cu reaction with the substrate for 30min at a temperature higher than $650^{\circ}C$.