• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.477-480
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• 2005

In this paper, the concept of sustainability was applied to mechanical design and manufacturing of mobile-phone case. A new evaluation method to find products' good and weak point for sustainability was developed. Two mobile phones were evaluated using the evaluation tool. As a result, electro-magnetic (EM) wave was considered as a harmful factor of the products, and improved front panel was made using nano particles that absorb EM waves. The EM shielding tests revealed that silver nano powders absorbed EM while MWCNT had no effect.

• Journal of Powder Materials
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• v.24 no.6
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• pp.464-471
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• 2017

A metal mesh TCE film is fabricated using a series of processes such as UV imprinting of a transparent trench pattern (with a width of $2-5{\mu}m$) onto a PET film, filling it with silver paste, wiping of the surface, and heat-curing the silver paste. In this work nanosized (40-50 nm) silver particles are synthesized and mixed with submicron (250-300 nm)-sized silver particles to prepare silver paste for the fabrication of metal mesh-type TCE films. The filling of these silver pastes into the patterned trench layer is examined using a specially designed filling machine and the rheological testing of the silver pastes. The wiping of the trench layer surface to remove any residual silver paste or particles is tested with various mixture solvents, and ethyl cellosolve acetate (ECA):DI water = 90:10 wt% is found to give the best result. The silver paste with 40-50 nm Ag:250-300 nm Ag in a 10:90 wt% mixture gives the highest electrical conductance. The metal mesh TCE film obtained with this silver paste in an optimized process exhibits a light transmittance of 90.4% and haze at 1.2%, which is suitable for TSP application.

• Advances in nano research
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• v.2 no.3
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• pp.147-155
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• 2014

Among the various nanoparticles reported for commercial applications, considerable interest has been generated by the use of silver nanoparticles. Owning to extremely small size, silver nanoparticles exhibit enhanced properties when compared with the bulk material. In this research work, silver nanoparticles were prepared by the reduction of silver salt with a reducing agent by a solvothermal method using different solvent mediums such as ethanol, hexane, toluene and acetone with water. The prepared silver nanoparticles were characterized systematically by X-ray diffraction (XRD), particle size analysis and scanning electron microscope (SEM). The results revealed the formation of pure silver phase and nano-sized particles. Among the different solvent mediums used, the silver nanoparticles prepared by hexane and water as solvent mixture resulted in very low particle size.

• Restorative Dentistry and Endodontics
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• v.39 no.2
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• pp.109-114
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• 2014

Objectives: Recurrent caries was partly ascribed to lack of antibacterial properties in composite resin. Silver and zinc nanoparticles are considered to be broad-spectrum antibacterial agents. The aim of the present study was to evaluate the antibacterial properties of composite resins containing 1% silver and zinc-oxide nanoparticles on Streptococcus mutans and Lactobacillus. Materials and Methods: Ninety discoid tablets containing 0%, 1% nano-silver and 1% nano zinc-oxide particles were prepared from flowable composite resin (n = 30). The antibacterial properties of composite resin discs were evaluated by direct contact test. Diluted solutions of Streptococcus mutans (PTCC 1683) and Lactobacillus (PTCC 1643) were prepared. 0.01 mL of each bacterial species was separately placed on the discs. The discs were transferred to liquid culture media and were incubated at $37^{\circ}C$ for 8 hr. 0.01 mL of each solution was cultured on blood agar and the colonies were counted. Data was analyzed with Kruskall-Wallis and Mann-Whitney U tests. Results: Composites containing nano zinc-oxide particles or silver nanoparticles exhibited higher antibacterial activity against Streptococcus mutans and Lactobacillus compared to the control group (p < 0.05). The effect of zinc-oxide on Streptococcus mutans was significantly higher than that of silver (p < 0.05). There were no significant differences in the antibacterial activity against Lactobacillus between composites containing silver nanoparticles and those containing zinc-oxide nanoparticles. Conclusions: Composite resins containing silver or zinc-oxide nanoparticles exhibited antibacterial activity against Streptococcus mutans and Lactobacillus.

• Journal of the Korean Ceramic Society
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• v.41 no.9
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• pp.670-676
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• 2004

The synthesis of highly concentrated silver nano sol assisted by polymeric dispersant (polyelectrolytes) for inkjet method was studied. The silver nano sol was prepared with AgNO$_3$, polyelectrolytes (HS5468cf ; polyacrylic ammonium salt), and reducing agent. The polyelectrolytes play an important role in formation of complex composed of Ag$\^$+/ion and carboxyl group (COO$\^$-/), result in preparation of highly dispersed silver nano particles. The optimization of added amount of polyelectrolytes, and concentration of silver nano sol was studied. The silver nanoparticles were evaluated by XRD, particle size/zeta potential analyzer and FE-TEM. The silver nanoparticles with the range of 10 nm in diameter were produced. The concentration of batch-synthesized silver nano sol was possible up to 40 wt%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1331-1334
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• 2004

The research on electromagnetic shielding has been advanced for military applications as well as for commercial products. Utilizing the reflective properties and absorptive properties of shielding material, the replied signal measured at the rear surface or at the signal source can be minimized. The shielding effect was obtained from materials having special absorptive properties or from structural characteristics such as stacking sequence. Recently researchers studied the electromagnetic properties of nano size particles. In this research {glass fiber}/{epoxy}/{nano particle} composites(GFR-Nano composites), was fabricated using various nano particles, and their properties in electromagnetic shielding were compared. For the visual observation of the nano composite materials, SEM(Scanning Electron Microscope) and TEM(Transmission Electron Microscope) were used. For the measurement of electromagnetic shielding, HP8719ES S-parameter Vector Network Analyser System was used on the frequency range of 8 GHz～12GHz. Among the nano particles, carbon black and Multi-Walled Carbon Nano-Tube (MWCNT) revealed outstanding electromagnetic shielding. Although silver nano particles (flake and powder) were expected to have effective electromagnetic shielding due to their excellent electric conductivities, test showed little shielding effect.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.1
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• pp.9-14
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• 2008

A Nano particle is a small particle with at least one dimension less than 100 nm Nanoparticle is currently used in an area cf intense scientific research, due to a wide variety cf potential applications in biomedical, optical, and electronic fields. In order to know the biological effect of the nine Nano particles on fertilized egg of Crassostrea gigas experiments were performed Development rates of control (free Nano particles) C. gigas to a particular larval stage (D-shape) was 78%. Development rate of C gigas to a parcicular larval stage (D-shape) after 24 hours exposure to 0.05ppm of AGZ020, Nano silver, P-25 and SnO were 22%, 52%, 58% and 76%, respectively. However, all fertilized eggs were destructed within 8 hours afters exposure to 20ppm of respective particles. On the other hand, All fertilized eggs were not affected after 24 hours respective exposure to 0.05ppm of In, Sb, Sn, Zn, and Ag-$TiO_2$ particles. However, development rates of C. gigas after 24 hours exposure to 20ppm of In, Sb, Sn, Zn, Ag-$TiO_2$ were 57%, 60%, 50%, 65%, and 64% respectively.

• Journal of Powder Materials
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• v.17 no.4
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• pp.295-301
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• 2010

Multi shell graphite coated Ag nano particles with core/shell structure were successfully synthesized by pulsed wire evaporation (PWE) method. Ar and $CH_4$ (10 vol.%) gases were mixed in chamber, which played a role of carrier gas and reaction gas, respectively. Graphite layers on the surface of silver nano particles were coated indiscretely. However, the graphite layers are detached, when the particles are heated up to $250^{\circ}C$ in the air atmosphere. In contrast, the graphite coated layer was stable under Ar and $N_2$ atmosphere, though the core/shell structured particles were heated up to $800^{\circ}C$. The presence of graphite coated layer prevent agglomeration of nanoparticles during heat treatment. The dispersion stability of the carbon coated Ag nanoparticles was higher than those of pure Ag nanoparticles.

• Advances in nano research
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• v.2 no.2
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• pp.111-119
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• 2014

The chemical synthesis of anisotropic defective polyaniline/Ag composite (PANI/Ag) is explored using silver nitrate ($AgNO_3$) as the precursor material. This study provides a simple method for the formation of PANI/Ag nanocomposites at two different aniline concentrations $5{\mu}l$ (PANC5) and $10{\mu}l$ (PANC10). The composite PANC5 exhibits UV-Visible absorption peaks at 436 nm and 670 nm whereas, PANC10 exhibits absorption peaks at 446 nm and 697 nm. This shift is caused by the strong interaction between polyaniline and silver. The characterized FTIR peaks observed at around $3410cm^{-1}$ (PANC5) and $3420cm^{-1}$ (PANC10) was due to the N-H stretching vibrations. The appearance of a broad band instead of a sharp peak can be attributed due to the presence of a high concentration of N-H groups in the nanocomposite. The TEM images show that the sample contains defective spherical, truncated triangular and rod shaped particles. The results showed that the PANI/Ag nanocomposites are composed of nano-sized particles of 43-53 nm that contain Ag domains of 33-37 nm with polymer thickness 5.7-11.2 nm at two different aniline concentrations.

• Journal of the Korean Chemical Society
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• v.52 no.4
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• pp.345-349
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• 2008