• Journal of Science and Technology Studies
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• v.13 no.2
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• pp.173-206
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• 2013

Launched by Samsung in 2003, nano-silver washing machines were a representative application of nanotechnology in commercial products until the US Environment Protection Agency (EPA) decided to regulate companies that produce nano-silver products in 2006. A year later, however, the EPA reclassified the washing machines not as an application of nanotechnology but as an ion-generating machine. As shown by the EPA's equivocation on this issue, establishing a category for nano-silver material should be considered in the procedure of risk assessment and regulation. This paper analyzes the controversy over Samsung's nano-silver washing machines more in detail to study how the demarcation between silver ion and nano-silver can vary according to the risk perception of nanotechnology. In Korea and the US, the boundary between silver ion and nano-silver was malleable and mobilzed depending on the contexts. Based on an analysis of the recent history of nano-silver washing machines, this paper explores the influence of risk perception over the ontological perspectives on a certain material.

• Korean Journal of Food Science and Technology
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• v.46 no.3
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• pp.347-351
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• 2014

We studied the green synthesis and antibacterial activity of chitosan-silver (Ag) nanocomposite films for application in food packaging. Green synthesis of Ag nanoparticles (AgNPs) was achieved by a chemical reaction involving a mixture of chitosan-silver nitrate ($AgNO_3$) in an autoclave at 0.1 MPa, $121^{\circ}C$, for 15-120 s. The formation of AgNPs in chitosan was confirmed by both UV-Visible spectrophotometry and transmission electron microscopy (TEM) and the effects of chitosan-$AgNO_3$ concentration and reaction time on the synthesis of AgNPs in chitosan were examined. The resulting chitosan-Ag composite films were characterized by various analytical techniques and their antibacterial activity was evaluated based on the formation of halo zones around films, indicating inhibition of the growth of Escherichia coli. A fourier-transform infrared (FTIR) spectroscopy analysis showed that free amino groups in chitosan acted as effective reductants and AgNP stabilizers. The composite films exhibited enhanced antibacterial activity with increasing Ag content on the surface of as-prepared composite films.

• Clean Technology
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• v.20 no.2
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• pp.160-165
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• 2014

Over the past decade, an increasing number of manufactured nanoparticles (NPs) have been incorporated into products and manufacturing processes due to the rapid innovation and commercialization in the field of nanotechnology. In addition, these nanomaterials and nano-consumer products have increased in quantity per year, and thus their uncontrolled release into the environment is anticipated to grow dramatically in future. However, A current sewage/wastewater treatment plant (SWTP) is being applied to removal of nanoparticles in wastewater. In Korea, the study on the removal of nanoparticles in SWTP was not reported yet. Therefore, in this work, to design pilot STP before field test, two model equations and commercial process simulation were used to derive the desing parameters.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.3
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• pp.263-270
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• 2016

Recent Engineered nanoparticles were increasingly exposed to environmental system with the wide application and production of nanomaterials, concerns are increasing about their environmental risk to soil and groundwater system. In order to assess the transport behavior of silver nanoparticles (AgNPs), a saturated packed column experiments were examined. Inductively coupled plasma-mass spectrometry and a DLS detector was used for concentration and size measurement of AgNPs. The column experiment results showed that solution chemistry had a considerable temporal deposition of AgNPs on the porous media of solid glass beads. In column experiment, comparable mobility improvement of AgNPs were observed by changing solution chemistry conditions from salts (in both NaCl and $CaCl_2$ solutions) to DI conditions, but in much lower ionic strength (IS) with $CaCl_2$. Additionally, the fitted parameters with two-site kinetic attachment model form the experimental breakthrough curves (BTCs) were associated that the retention rates of the AgNPs aggregates were enhanced with increasing IS under both NaCl and $CaCl_2$ solutions.

• Microbiology and Biotechnology Letters
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• v.39 no.1
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• pp.77-85
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• 2011

The antibacterial activities of silver nanoparticles (Ag-NPs) were studied with respect to Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli by observing the bacterial cells treated or not with Ag-NPs by FE-SEM as well as measuring the growth curves, formation of bactericidal ROS, protein leakage, and lactate dehydrogenase activity involved in the respiratory chain. Bacterial cells were treated with Ag-NPs powder, and the growth rates were investigated under varying concentrations of Ag-NPs, incubation times, incubation temperatures, and pHs. As a result, S. aureus and E. coli were shown to be substantially inhibited by Ag-NPs, and the antibacterial activity of Ag-NPs did not fluctuate with temperature or pH. These results suggest that Ag-NPs could be used as an effective antibacterial material.

• Korean Journal of Environmental Biology
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• v.34 no.3
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• pp.183-192
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• 2016

Silver nanomaterials have been intensively applied in consumer products of diverse industrial sectors because of their strong biocidal properties and reported to be hazardous to aquatic organisms once released in the environment. Nanomaterials including sliver, are known to be different in toxicity according to their physicochemical characteristics such as size, shape, length etc. However studies comparing toxicity among silver nanomaterials with different physicochemical characteristics are very limited. Here, toxicities of silver nanomaterials with different size (50, 100, 150 nm), length (10, $20{\mu}m$), shape (wire, sphere), and coating material (polyvinylpyrrolidone, citrate) using OECD test guidelines were evaluated in aquatic species (zebrafish, daphnia, algae) and compared. On a size property, the smaller of silver nanomaterials, the more toxic to tested organisms. Sphered type of silver nanomaterials was less toxic to organisms than wired type, and shorter nanowires were less toxic than longer ones. Meanwhile the toxic effects of materials coated on silver nanomaterials were slightly different in each tested species, but not statistically significant. To the best of our knowledge, it is first investigation to evaluate and compare ecotoxicity of silver nanomaterials having different physicochemical characteristics using same test species and test guidelines. This study can provide valuable information for human and environmental risk assessment of silver nanomaterials and guide material manufacturers to synthesize silver nanomaterials more safely to human and environment.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.46.1-46.1
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• 2009

산업이 점차 발달함에 따라 발생하는 환경오염으로 인해 인간의 삶에 있어 불가분의 관계에 있는 물에 대한 관심이 지속적으로 높아지고 있는 추세이다. 각종 질병의 요인이 되는 박테리아는 주로 물을 운송 매개체로 하기 때문에 이로 인한 물의 오염으로 인도의 경우 모든 질병 발생의 80%를 차지하는 것으로 세계보건기구(WHO)에 의해 보고되었다. 현재까지물 또는 공기의 항균 및 살균 정화를 위해 화학적, 생물학적 방식 등 다양한 기술이 개발되었으나 박테리아와같은 세균제거에는 무리가 있는 실정이다. 따라서 본 연구에서는 여러 물질 중에서도 특히 항균작용(Antibacterial activity)이 탁월한 은(Ag)을 나노입자화하여 in-situ 코팅을 통한 다공성 알루미늄 하이드록사이드 나노복합재의 제조함으로써 생물학, 생체의용공학, 약학 등에 응용될 수 있는 새로운 형태의 항균재료제조방법을 제안하였다. 우선, 다공성 알루미늄 하이드록사이드기판은 알루미늄 기판에 알칼리 표면개질을 실시함으로서 표면에 마이크로포어가 형성된 알루미늄 하이드록사이드 기판을 제조하였다. 이렇게 제조된 다공성 기판에 Polyol 공정으로 은나노입자를 합성 및 분산시킴으로서 in-situ로 은나노입자가 분산된 알루미늄 하이드록사이드 나노복합재 기판을 만들수 있었다. 본 연구를 통하여 제조된 은나노입자가 분산된 알루미늄 하이드록사이드 나노복합재 기판은 주사전자현미경(SEM) 및 투과전자현미경(TEM)을 통하여 미세구조와 상분석을 실시하였으며 X선 광전자분석(XPS)를 이용하여 기판 표면의 화학적 상태를 분석하였다.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.4
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• pp.361-367
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• 2016

Pollutants removal and disinfection effect of secondary effluent from final settling tank of sewage treatment plant of W city were investigated in Loop Reactor using ordinary granular activated carbon(GAC) and GAC coated with silver nanoparticles. The results showed that the removal efficiency of $COD_{Mn}$, T-N and T-P using GAC with silver nanoparticles were higher than using the ordinary GAC. The removal efficiency of T-P using GAC with silver nanoparticles is 45.4% and that of T-P using ordinary GAC is 30.9% in the same case of the input amount of 20 g/L of GAC. The total califorms is reduced according to increasing input amount of GAC with silver nanoparticles and ordinary GAC. The disinfection efficiency of total coliforms in case of GAC with silver nanoparticles is much higher than that in case of ordinary GAC. For all experiments using the silver nanoparticles, the total coliforms is under 26 cfu/mL and this shows very excellent disinfection effect.

• Particle and aerosol research
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• v.12 no.3
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• pp.95-102
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• 2016

Controlling exposures to occupational hazards is important for protecting workers. Certified facepiece respirators are recommended when engineering controls do not adequately prevent exposures to airborne nanomaterials. The objective of this study is to carry out the experimental performance test to investigate the fractional efficiencies of the filter media for two grades of facepiece respirators. Experimental performance evaluations were carried out for the test NaCl particles and silver nanoparticles. For media of respirator filter, the penetration of NaCl particles was less than 5% and the most penetrating particle size occurred at about 40 nm. For silver nanoparticles, the most penetrating particle size was about 20nm with higher efficiency than those of NaCl particles. Charge characteristics of airborne nanoparticles is important because the media of respirator filter is made by the electret filter media.

• Korean Journal of Ecology and Environment
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• v.42 no.1
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• pp.75-84
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• 2009

The effect of various SNPs (silver nanoparticles) on the growth of Microcystis aeruginosa was investigated in laboratory and field experiment. Four SNPs, namely JS47N, JS47N-K2, JS47N/3-1 and JS47N/3-2 were used to this study. The Ag size, concentration and color of these solutions were about $20{\sim}40nm$, $200mg\;L^-1$ and brown, respectively. At 0.01 and $0.1mg\;L^-1$, SNPs inhibited the growth of unicellular M. aeruginosa by 99.4% and 99.9%, respectively. However, SNPs of $1mg\;L^-1$ inhibited the growth of colonial M. aeruginosa by 98.5%, whereas the other three concentrations (0.001, 0.01 and $0.1mg\;L^-1$) had little inhibitory effect. In experimental enclosures from eutrophic lake, cyanobacteria including M. aeruginosa were found to be more sensitive to the SNPs than green algae and diatoms. In conclusion, our study indicates that SNPs has a selective cyanocidal potential when used to M. aeruginosa. We believe that future studies need to test on various other organisms, and determine minimum concentration for field application.