• Journal of Powder Materials
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• v.15 no.4
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• pp.314-319
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• 2008

Nano-sized tungsten disulfide ($WS_2$) powders were synthesized by chemical vapor condensation (CVC) process using tungsten carbonyl ($W(CO)_6$) as precursor and vaporized pure sulfur. Prior to the synthesis of tungsten disulfide nanoparticles, the pure tungsten nanoparticles were produced by same route to define the optimum synthesis parameters, which were then successfully applied to synthesize tungsten disulfide. The influence of experimental parameters on the phase and chemical composition as well as mean size of the particles for the produced pure tungsten and tungsten disulfide nanoparticles, were investigated.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.5
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• pp.223-228
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• 2017

Aluminum nitride (AlN) powder was successfully synthesized at low temperature via carbothermal reduction and nitridation (CRN) assisted by microwave heating. The synthesis processes of AlN powder were investigated with X-ray diffraction, FE-SEM, FT-IR and TGA/DSC. Aluminum nitrate was used as an oxidizer and aluminum source, urea as fuel, and glucose as carbon source. These starting materials were mixed with D.I water and reacted in a flask at $100^{\circ}C$ for 20 minutes. After the reaction was finished, black foamy intermediate product was formed, which was considered to be an amorphous $Al_2O_3$ particles through intermediate product obtained by solution combustion synthesis (SCS) at the results of X-ray diffraction patterns and FT-IR. This intermediate product was nitridated at temperatures of $1300^{\circ}C$ and $1400^{\circ}C$ in $N_2$ atmosphere by a microwave heating furnace and then decarbonated at $600^{\circ}C$ for 2 hours in air. It should be noticed from FE-SEM images that as nitridated particles, identified as AlN from X-ray diffraction patterns, are covered with carbon residues. After decarbonating the nitridated powders, the spherical pure AlN powders were obtained without alumina and their particle sizes were dependent on the nitridating temperature with high temperature of $1400^{\circ}C$ giving large particles of around 70~100 nm.

• Proceedings of the KIEE Conference
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• 2009.04a
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• pp.30-32
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• 2009

In this study, $CuInS_2$ powders have been synthesized using polyol process of a mixture of copper nitrate, indium nitrate, and thiourea with various stoichiometric molar ratios in ethylene glycol at 196$^{\circ}C$. As boiling time goes by, the color of metal ion mixed solutions were changed transparent green to dark green and finally fumed to black by reduction of $OH^-$ radicals. The prepared powders were fully characterized by SEM, XRD and UV-Vis. The particle shape of black colored powders showed sphere with about 30 nm in particle size compared to those with dark green colored powders showed irregular shape with about 1 ${\mu}m$ in particle size. The XRD results showed highly crystallized $CuInS_2$. The UV-Vis spectra showed broad shoulder at 430 and 780 nm corresponding to 2.78 and 1.58 eV for the dark green colored one and black colored one, respectively.

• The Journal of Advanced Prosthodontics
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• v.9 no.6
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• pp.482-485
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• 2017

PURPOSE. This laboratory study aimed to investigate the effect of doping an acrylic denture base resin material with nanoparticles of ZnO, CaO, and $TiO_2$ on biofilm formation. MATERIALS AND METHODS. Standardized specimens of a commercially available cold-curing acrylic denture base resin material were doped with 0.1, 0.2, 0.4, or 0.8 wt% commercially available ZnO, CaO, and $TiO_2$ nanopowder. Energy dispersive X-ray spectroscopy (EDX) was used to identify the availability of the nanoparticles on the surface of the modified specimens. Surface roughness was determined by employing a profilometric approach; biofilm formation was simulated using a monospecies Candida albicans biofilm model and a multispecies biofilm model including C. albicans, Actinomyces naeslundii, and Streptococcus gordonii. Relative viable biomass was determined after 20 hours and 44 hours using a MTT-based approach. RESULTS. No statistically significant disparities were identified among the various materials regarding surface roughness and relative viable biomass. CONCLUSION. The results indicate that doping denture base resin materials with commercially available ZnO, CaO, or $TiO_2$ nanopowders do not inhibit biofilm formation on their surface. Further studies might address the impact of varying particle sizes as well as increasing the fraction of nanoparticles mixed into the acrylic resin matrix.

• Journal of Power System Engineering
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• v.17 no.1
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• pp.104-109
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• 2013

Tin and Tinoxide nanoparticles were prepared by arc-discharge nanopowder process. The negative electrode were fabricated using Tin and Tinoxide nanopower. The microstructure and electrochemistry properties were investigated and compared between Tin and Tinoxide. The oxidation film has microstructure of core/shell type and the shell which was attached around Tin nanoparticle consisted of amorphous $SnO_2$. The shape of Tinoxide nanoparticles was formed with irregular shape in comparison with Tin particle. Initial discharge capcity of Tinoxide electrode possesed about 1000mAh/g, which is about 320mAh/g higher than Tin electrode. Irreversible capacity of Tin electrode is much higher than Tinoxide. The cycle performance of Tinoxide electrode was indicated that is batter than Tin. The Tin negative electrode lost most of capacity after 4 cycle but Tinoxide electrode still retained the capacity. The Tinoxide does show some promise as Li-ion battery anode due to their large reversible capacity at low potentials.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2005.05a
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• pp.27-39
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• 2005

나노기술은 21세기 초반 첨단산업을 이끌어갈 핵심기술 중의 하나로 여러 나라들이 국가적인 차원에서 전략적으로 개발하고 있다 나노기술은 초정밀 가공기술, 원자 혹은 분자 단위의 조립(조합)기술, 소재공정기술 등의 기술 분야를 포함하며 나노스케일 영역에서 나노소재를 이용(제조 및 가공)하여 새로운 응용분야를 창출해 내거나 기존 산업을 더욱 고도화하는데 기여하는 기술이다. 나노소재는 금속, 세라믹, 고분자, 생체물질 등의 특정 물질 영역에 국한되지 않고 다양한 형태, 다양한 물성을 갖고 있으며 나노기술 구현에 있어서 직접적인 대상 혹은 중간매체에 해당한다. 따라서 나노소재 기술은 대단히 광범위한 영역을 포함하는 나노기술의 바탕을 이루는 기반기술 또는 원천기술이라고 할 수 있다. 여러 형태의 나노소재 중에서 가장 저차원(0차원)의 물질에 해당하는 나노분말은 기술적으로 가장 실용화에 근접해 있으며 이미 많은 상용화 사례들이 나타나고 있다. 나노분말 기술은 기술 성숙도 측면에서뿐만 아니라 확장성(유용성), 신규성(혁신성) 측면에서 대단한 가능성을 갖고 있기 때문에 향후 대단히 빠른 속도로 시장이 확대될 전망이다. 본 발표에서는 나노분말 기술의 개발 현황 및 전망에 대하여 언급하고자 한다.

• Journal of Powder Materials
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• v.17 no.5
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• pp.379-384
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• 2010

In the present work, bismuth nanopowders with various particle size distributions were synthesized by controlling argon (Ar) gas flow rate and chamber pressure of a gas condensation (GC) apparatus. From the analyses of transmission electron microscopy (TEM) images and nitrogen gas adsorption results, it was found that as Ar gas flow rate increased, the specific surface area of bismuth increased and the average particles size decreased. On the other hand, as the chamber pressure increased, the specific surface area of bismuth decreased and the average particles size increased. The optimum gas flow rate and chamber pressure for the maximized electrochemical active surface area were determined to be 8 L/min and 50 torr, respectively. The bismuth nanopowders synthesized at the above condition exhibit 13.47 $m^2g^{-1}$ of specific surface area and 45.6 nm of average particles diameter.

• Journal of the Korean Society for Heat Treatment
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• v.22 no.3
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• pp.149-154
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• 2009

Dense $5Cu_{0.6}Fe_{0.4}-Al_2O_3$ composite was consolidated from mechanically synthesized powders by pulsed current activated sintering method within 1 min. $5Cu_{0.6}Fe_{0.4}-Al_2O_3$ powder was synthesized from 3CuO and 2FeAI using the high energy ball milling. Dense $5Cu_{0.6}Fe_{0.4}-Al_2O_3$ with relative density of up to 95% was produced under simultaneous application of a 80 MPa pressure and the pulsed current. Mechanical properties and grain size of the composite were investigated.

• Proceedings of the Korean Society of Toxicology Conference
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• 2005.05a
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• pp.27-39
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• 2005

나노기술은 21세기 초반 첨단산업을 이끌어갈 핵심기술 중의 하나로 여러 나라들이 국가적인차원에서 전략적으로 개발하고 있다. 나노기술은 초정밀 가공기술, 원자 혹은 분자 단위의 조립(조합)기술, 소재공정기술 등의 기술 분야를 포함하며 나노스케일 영역에서 나노소재를 이용(제조 및 가공)하여 새로운 응용분야를 창출해내 거나 기존 산업을 더욱 고도화하는데 기여하는 기술이다. 나노소재는 금속, 세라믹, 고분자, 생체물질 등의 특정 물질 영역에 국한되지 않고 다양한 형태, 다양한 물성을 갖고 있으며 나노기술 구현에 있어서 직접적인 대상 혹은 중간매체에 해당한다. 따라서 나노소재기술은 대단히 광범위한 영역을 포함하는 나노기술의 바탕을 이루는 기반기술 또는 원천기술이라고 할 수 있다. 여러 형태의 나노소재 중에서 가장 저차원(0차원)의 물질에 해당하는 나노분말은 기술적으로 가장 실용화에 근접해 있으며 이미 많은 상용화 사례들이 나타나고 있다. 나노분말 기술은 기술 성숙도 측면에서 뿐만 아니라 확장성(유용성), 신규성(혁신성) 측면에서 대단한 가능성을 갖고 있기 때문에 향후 대단히 빠른 속도로 시장이 확대될 전망이다. 본 발표에서는 나노분말 기술의 개발 현황 및 전망에 대하여 언급하고자 한다.

• Journal of Powder Materials
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• v.17 no.2
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• pp.101-106
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• 2010

In this study, we successfully synthesized a nano-sized lanthanum-modified lead-titanate (PLT) powder with a perovskite structure using a high-energy mechanochemical process (MCP). In addition, the sintering behavior of synthesized PLT nanopowder was investigated and the sintering temperature that can make the full dense PLT specimen decreased to below $1050^{\circ}C$ by using $Bi_2O_3$ powder as sintering agent. The pure PLT phase of perovskite structure was formed after MCP was conducted for 4 h and the average size of the particles was approximately 20 nm. After sintered at 1050 and $1150^{\circ}C$, the relative density of PLT was about 93.84 and 95.78%, respectively. The density of PLT increased with adding $Bi_2O_3$ and the specimen with the relative densitiy over 96% were fabricated below $1050^{\circ}C$ when 2 wt% of $Bi_2O_3$ was added.