• Journal of Korean Society of Environmental Engineers
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• v.29 no.9
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• pp.1020-1026
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• 2007

The control of pathogenic microorganisms is important issue in human environments, especially in surface area. However, surface disinfection has not been fully researched. In this study, the surface disinfection under UV irradiation was performed to investigate the quantitative kinetics for Bacillus subtilis spore inactivation in several experimental conditions, such as light intensity, temperature and surface roughness. This study reports that UV light would apparently inactivates the microorganisms and the required IT value for 2 log (99%) Bacillus subtilis spore inactivation was found to be 14.5 $mJ/cm^2$ in plain surface, as predicted by the Delayed Chick-Watson model. When UV was irradiated, there were no significant temperature effects. However, the experimental result shows that the more increased IT values are required at larger surface roughness.

• Korean Journal of Weed Science
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• v.6 no.2
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• pp.146-153
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• 1986

The study was conducted to estimate the oxyfluorfen inactivation proceeding which have or have not organism and soil microorganism in soil by biological testing method, under the different condition of soil class and temperature. The results obtained in this experiment are as follows: 1. Under the condition of high temperature, chemical`s inactivation resulted in early and the extent of it`s inactivation was increased. 2. The extent of inactivation was more rapid in the sandy soil than in the clay. 3. Among the soil class, the differentiation of the day of demand with inactivation at the 50% and 95% was significantly increased low temperature period. 4. In sandy soil, inactivation`s differentiation by adding organism was found, but by adding microorganism was not found. 5. In clay, chemical's inactivation was increased rather by adding microorganism than by adding organism. 6. Among under the condition of soil class, by adding organism and micrrorganism, chemical`s inactivation (Probit growing period at 50% and 95%) was shorted. And among the soil class, it was shortter sandy soil than clay or silty loam soil.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.11
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• pp.1063-1068
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• 2010

This study compared UV and UV/$H_2O_2$ inactivation of E.coli, a possible indicator microorganism for fecal contamination of water, and $Q{\ss}$ phage, an indicator for pathogenic viruses. UV inactivation of $Q{\ss}$, T4 and lambda phages in actual secondary effluent was investigated, too. As a result, similar inactivation efficiency between $Q{\ss}$ phage and E.coli was observed during UV treatment, while $Q{\ss}$ phage showed higher resistance to UV/$H_2O_2$ than E.coli. $Q{\ss}$ phage resistance to UV or UV/$H_2O_2$ does not reflect those of all pathogenic viruses. However, the result tells that the use of E.coli inactivation efficiency in evaluating microbiological safety of water could not always ensure the sufficient safety from pathogenic viruses. Meanwhile, $Q{\ss}$ phage showed less resistance to UV than T4 and lambda phages, indicating that the use of $Q{\ss}$ phage as an indicator virus may bring insufficient disinfection effectiveness by causing the introduction of lower UV dose than required. Consequently, it can be thought that T4 or lambda phages would be more desirable indicators in ensuring the sufficient disinfection effectiveness for various pathogenic viruses.

• Applied Chemistry for Engineering
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• v.21 no.4
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• pp.366-371
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• 2010

Accompanying the rapid advance of nanotechnology, various nano-particles have shown promise as strong antimicrobial agents against a broad spectrum of microorganisms. These nanoparticles also have potential applications in medical devices, water treatments systems, environmental sensors and so on. However, with increasing concerns about the impact of engineered nanoparticles, many researchers are recently reporting the cytotoxicity of nanoparticles. In this review paper, we summarized the antimicrobial activities and mechanisms of various kinds of engineered nanoparticles to imprale understanding about these characteristics of nanoparticles.

• Air Cleaning Technology
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• v.9 no.1 s.32
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• pp.45-57
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• 1996

• Journal of Korean Society of Environmental Engineers
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• v.27 no.7
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• pp.771-776
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• 2005

In recent days, there is much interest in the biocidal activity of silver since silver is known to be safe and effective as disinfectant and biocidal material against coliforms and viruses. In particular, nano silted silver particles which can be used as effective biocidal material received more attention. Accordingly, it is important to investigate antimicrobial activity and mechanism of nano sized silver particles prepared in a cost-effective manner. In this study, nano sized silver particles were prepared via photoreduction of a silver salt ($AgNO_3$) in the bulk phase of $PEO_{20}-PPO_{70}-PEO_{20}$ (Pluronic 123) block copolymer The antimicrobial efficacy of silver nano particles against E. coli was investigated and compared with that of silver ion as the concentration of silver nano particles, pH ($5.6{\sim}8.2$), temperature ($4^{\circ}C{\sim}35^{\circ}C$) varied in aqueous system. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) was used to examine the nature of damaged microorganism with nano sized silver particles and silver ion. This study showed that antimicrobial efficacy of silver nano particles was approximately one twentieth than that of silver ion. It was more biocidal at higher pH in contrast with silver ion. In addition, nano silver particles was demonstrated to disrupt the outer membrane of E. coli, subsequently causing their aggregation. On the other hand, silver ion diffused into the cell damaging the cytoplasmic membrane without disrupting the outer membrane of E. coli.

• Applied Chemistry for Engineering
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• v.20 no.3
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• pp.251-257
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• 2009

Recently, there is much interest in the antimicrobial activity of silver since silver has known to be safe and effective as a disinfectant or an antimicrobial agent against a broad spectrum of microorganisms. Although silver has been applied to various kinds of products due to the effective antimicrobial activity, the quantitative antimicrobial activity or detailed mechanism of silver is not clearly investigated yet, causing the controversy and confusion. In this review paper, we summarized the characteristics, antimicrobial activities and mechanisms, synergistic effects with other antimicrobials, and applicability of silver.

• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.991-996
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• 1995

Effects of high hydrostatic pressure on microorganisms and browning enzymes in Angelica keiskei juice were investigated using response surface methodology. The optimum process condition for maximum reduction of total aerobes was $5700\;kg_f/cm^2$ (558.6 MPa) pressure and 7.16 min process time, and 3.44 log cycle reduction of total aerobes was predicted at the optimum condition. E. coli, initially $8.8{\times}10^3\;CFU/ml$, was completely inactivated by high hydrostatic pressure at all process conditions ($3800{\sim}6700\;kg_f/cm^2\;pressure;\;3{\sim}17\;min\;process\;time$). Polyphenol oxidase and peroxidase were partly inactivated by the high hydrostatic pressure. It was also indicated that inactivation of microorganisms and browning enzymes by hydrostatic pressure is dependent on pressure rather than process time.

• Microbiology and Biotechnology Letters
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• v.33 no.4
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• pp.302-307
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• 2005

The inactivation efficiency of Campylobacter jejuni were assessed in vitro and in vivo using confocal laser microscopy and flow cytometry. C. jejuni cells were inactivated with $1\%$ (w/v) trisodium phosphate (TSP) and the live cells and inactivated cells were distinguished by staining with LIVE/DEAD BacLight Bacteria Viability fluorescent probe. After treatment of TSP for 5 min, most of C. jejuni cells turned to coccoid form from original spiral shape. C. jejuni cells lost total cell viability in the absence of organic nutrients but did not lost total cell viability in the presence of organic nutrients. In vivo test, C. jejuni cells turned to viable but non-culturable (VBNC) form after TSP treatment and remained alive on chicken skin. C. jejuni cells attached on chicken meat would transform to coccoid form by sanitizer treatment, but could possibly be alive by the benefits of organic nutrients present in chicken meat.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.9
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• pp.692-700
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• 2011

The use of electric field has been studied as an alternative for biofilm control dominated by disinfectants and antibiotics. This technology would be advantageous in the environmental respect that biofilm can be controlled based on electron transfer, not using chemical disinfectants and antibiotics. Control mechanisms which were reported by earlier studies are organized as; (1) bacterial adhesion control by electrostatic repulsion at a negative current, (2) bacterial adhesion control using bacterial motion and (3) bacterial inactivation by direct oxidation at a positive current, (4) bioelectric effect leading to biofilm inactivation. In this review article, we summarized the technologies for biofilm control using electric field and provided some application examples from previous studies.