• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.12
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• pp.881-890
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• 2010

As Influenza A virus(H1N1) has been spreading more rapidly around globe, the study on the airborne disease which is transimitted through the respiratory system is on the rise. In this study, the multizone simulation of the public building against bioviolence is performed in the case of unexpected spread of microbial contaminants, such as bioviolence agent, Influenza A, Smallpox, B. anthrax and transport and control characteristics of above three kinds of bioviolence agents are evaluted. Results suggest that Influenza A and Smallpox which has small mean diameter can be more removable than B. anthrax by using high UVGI grade condition and B. anthrax which has large mean diameter can be more removable than Influenza A and Smallpox by using high filter grade condition. Results also suggest that installing a combined air treatment system is more effective to reduce the damage and engineers will use immune building technology for removing the bioviolence agents effectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.4
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• pp.291-298
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• 2007

The purpose of this study is to evaluate the efficacy of multizone simulation that enables to grasp of details about microbial contaminant problem in an multistoried apartment. We used actual indoor test data to figure up microbial contaminant level as initial value for the multizone simulation and estimated the various effects of indoor occupant infected with germs such as bacteria and fungus and the performance of air sterilization by using multizone simulation in substitute for infeasible experimental approach. The results show that natural ventilation make ourselves generally useful for removing indoor microbial contaminants. The results also show that the performance of air sterilization reach the maximum in the case of using mechanical ventilation and UVGI air sterilizer. The conclusion is that this multizone simulation is useful tool for actual design method for immune building systems.

• Journal of Microbiology and Biotechnology
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• v.25 no.11
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• pp.1928-1935
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• 2015

Microbial growth kinetics is often used to optimize environmental processes owing to its relation to the breakdown of substrate (contaminants). However, the quantification of bacterial populations in the environment is difficult owing to the challenges of monitoring a specific bacterial population within a diverse microbial community. Conventional methods are unable to detect and quantify the growth of individual strains separately in the mixed culture reactor. This work describes a novel quantitative PCR (qPCR)-based genomic approach to quantify each species in mixed culture and interpret its growth kinetics in the mixed system. Batch experiments were performed for both single and dual cultures of Pseudomonas putida and Escherichia coli K12 to obtain Monod kinetic parameters (μ_max and K_s). The growth curves and kinetics obtained by conventional methods (i.e., dry weight measurement and absorbance reading) were compared with that obtained by qPCR assay. We anticipate that the adoption of this qPCR-based genomic assay can contribute significantly to traditional microbial kinetics, modeling practice, and the operation of bioreactors, where handling of complex mixed cultures is required.

• Mycobiology
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• v.33 no.1
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• pp.41-50
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• 2005

Results from an innovative approach to improve remediation in the rhizosphere by encouraging healthy plant growth and thus enhancing microbial activity are reported. The effect of arbuscular mycorrhizal fungi (Am) on remediation efficacy of wheat, mungbean and eggplant grown in soil spiked with polyaromatic hydrocarbons (PAH) was assessed in a pot experiment. The results of this study showed that Am inoculation enhanced dissipation amount of PAHs in planted soil, plant uptake PAHs, dissipation amount of PAHs in planted versus unplanted spiked soil and loss of PAHs by the plant-promoted biodegradation. A number of parameters were monitored including plant shoot and root dry weight, plant tissue water content, plant chlorophyll, root lipid content, oxido-reductase enzyme activities in plant and soil rhizosphere and total microbial count in the rhizospheric soil. The observed physiological data indicate that plant growth and tolerance increased with Am, but reduced by PAH. This was reflected by levels of mycorrhizal root colonization which were higher for mungbean, moderate for wheat and low for eggplant. Levels of Am colonization increased on mungbean > wheat > eggplant. This is consistent with the efficacy of plant in dissipation of PAHs in spiked soil. Highly significant positive correlations were shown between of arbuscular formation in root segments (A)) and plant water content, root lipids, peroxidase, catalase polyphenol oxidase and total microbial count in soil rhizosphere as well as PAH dissipation in spiked soil. As consequence of the treatment with Am, the plants provide a greater sink for the contaminants since they are better able to survive and grow.

• Journal of Food Hygiene and Safety
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• v.8 no.4
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• pp.241-249
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• 1993

This study was performed to investigate the remainity of synthetic surfactant (LAS) by HPLC and the microbial contamination on stainless steel dishes. For the maintenance and the improvement of school lunch program's safety, the remainity of synthetic surfactants (LAS) on stainless steel dishes washed with auto dishwasher was investigated by HPLC, and the microbial contamination on same dishes was surveyed. The results were as follows: (1) The remainity of synthetic surfactant (LAS) a) The residue of LAS was very small because of the repeated washing of dishes by strong pressurized water. b) The remainity range of LAS on stainless steel dishes was 2.1~7.2 $\mu\textrm{g}$/dish. The remainity of general surfactants was higher in cold water then warm water. The amount of residual general surfatants was 5.95 $\mu\textrm{g}$/dish in cold water, and 2.95 $\mu\textrm{g}$/dish in warm water. There was no difference of the remainity of special surfactants by water temperature. The amount of residual surfactants was 3.9 $\mu\textrm{g}$/dish. c) There was no difference of residue amount by washing times. (2) The microbial contamination after washing with general surfactants. 1) The mean MPN of E. coli was 203(53~345) on 1 hr, 19(6~28) on 2 hrs, in cold water, and 1100(only 1 dish of 1 school) on 1 hr, 24(6~42) on 2hrs. 2) After washing with general surgactants the mean of contamination by general microbials was 956(25~2300)on 1 hr, 694(45~2500) on 2 hrs. in cold water and 803(5~2300) on 1 hr, 671(5~2500)on 2 hrs. After washing with special surfactants the mean of contamination by general microbials was 788(136~2900) on 1 hr, 1122(15~3000) on 2 hrs, in cold water and 537(5~2000) on 1 hr, 88(15~150) on 2 hrs in warm water. (3) Like the results of this study, the good washing methods of stainless steel dishes for school luch program were as follows. First, for washing stainless steel dishes, the use of special surfactants was recommended at 30~4$0^{\circ}C$ water. Second, at 7$0^{\circ}C$ water, the rinsing of dishes was recommended. Third, the final rinsing at 8$0^{\circ}C$ combined with simple disinfection and dry was recommended.

• Microbiology and Biotechnology Letters
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• v.50 no.1
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• pp.95-101
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• 2022

Due to the pandemic caused by COVID-19, the demand for face masks is soaring and has often caused a shortage. The aim of this study was to evaluate the effect of ultraviolet (UV) and drying treatments on microbial contaminants in facial masks. To conduct this study, standard procedures were designed to develop samples contaminated by the control bacteria Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The contamination level of the standard samples was approximately 6.30 × 10⁶ CFU/ml, and the UV light treatment was performed 1, 3, 5, and 7 times. To evaluate the effect of the UV and drying treatments, the masks were first treated with UV 1, 2, and 3 times, followed by the drying process. As a result, the mask contaminated with E. coli and P. aeruginosa showed a bacterial rate of approximately 99.9% after 1 UV irradiation, and in the case of the S. aureus-contaminated mask, it exhibited a bactericidal rate of approximately 99.9% after 7 UV irradiations. However, when the drying process was included after UV irradiation, all the samples contaminated with E. coli, S. aureus, and P. aeruginosa showed a bactericidal rate of 99.9% or more. The results of this study suggest that UV and drying treatments can effectively reduce the bacterial contaminants in facial masks. In addition, these results provide fundamental data and appropriate sterilization methods for reusing masks.

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.11b
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• pp.90-105
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• 2002

The dioxin- or aryl hydrocarbon receptor (AhR) is a member of the Per-Arnt-Sim family of nuclear transcription factors exhibiting a basic helix-loop-helix structure. In its non-ligated state the AhR is associated with hsp 90 and the immunophilin-type XAP2. Upon ligand binding the associated proteins are released, the receptor dimerizes with the AhR nuclear trans locator protein Arnt, and binds to XREs (xenobiotic-responsive elements) in the 5'-flanking region of responsive genes thus modulating their transcription.(omitted)

• 한국생물공학회:학술대회논문집
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• 2004.07a
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• pp.107-125
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• 2004

A bioremediation of petroleum-contaminated soil in Korea was evaluated for the optimization of enhanced biodegradation and the minimization of effects of seasonal variations, The short-term bioremediation in combination of biopile pretreatment and landfarming was performed by lowering contaminated levels and overcoming the inhibiting factors in the rainy and winter seasons. A microbial density was maintained with indigenous microbial addition for bioaugmentation and with fertilizers for biostimulation. A lesser volatile and biodegradable fraction due to their abiotic removals following the biopile pretreatment was effectively removed by the laterally applied landfarming. The optimal temperature in greenhouse was maintained by buffering of the soil temperature even with slight decreases in removal rates during the winter and extensive leaching of nutrients and contaminants was restricted with adjusting the water contents during the Korean rainy season. Although the tilling process was effective for biodegradation with aeration only, the simultaneous treatment due to apparent mixing of nutrients and microbes more favorably degraded the petroleum than the sequential treatment.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.11a
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• pp.196-201
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• 2000

The influence of adsorption on cadmium toxicity to soil microorganisms in smectite-rich soils and sediments was quantified as a function of solution and sorbent characteristics. Adsorption and surface complexation experiments were conducted to infer Cd sorption mechanisms to a reference smectite and three fractions of a Veritsol soil, and to elucidate the effects of the surface complexation on Cd bioavailability and toxicity in soils and sediments. Cadmium adsorption isotherms conformed to the Langmuir adsorption model, with adsorptive capacities of the different samples dependent on their characteristics. Equilibrium geochemical modeling (MINTEQA2) was used to predict the speciation of Cd in the soil suspensions using Langmuir and Triple Layer surface complexation models. The influence of adsorption and surface complexation on cadmium toxicity to soil microorganisms was assessed indirectly through the relative change in microbial hydrolysis of fluorescein diacetate (FDA) as a function of total Cd concentration and sorbent characteristics. Adsorption decreased the toxicity of Cd to soil microorganisms. Inner-sphere complexation is more effective than outer-sphere complexation in reducing the bioavailability and toxicity of heavy metals in soils and sediments.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.10a
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• pp.111-124
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• 2003

Processes that cause immobilization of contaminants in soil are of great environmental importance because they may lead to a considerable reduction in the bioavailability of contaminants and they may restrict their leaching into groundwater. Previous investigations demonstrated that pollutants can be bound to soil constituents by either chemical or physical interactions. From an environmental point of view, chemical interactions are preferred, because they frequently lead to the formation of strong covalent bonds that are difficult to disrupt by microbial activity or chemical treatments. Humic substances resulting from lignin decomposition appear to be the major binding ligands involved in the incorporation of contaminants into the soil matrix through stable chemical linkages. Chemical bonds may be formed through oxidative coupling reactions catalyzed either biologically by polyphenol oxidases and peroxidases, or abiotically by certain clays and metal oxides. These naturally occurring processes are believed to result in the detoxification of contaminants. While indigenous enzymes are usually not likely to provide satisfactory decontamination of polluted sites, amending soil with enzymes derived from specific microbial cultures or plant materials may enhance incorporation processes. The catalytic effect of enzymes was evaluated by determining the extent of contaminants binding to humic material, and - whenever possible - by structural analyses of the resulting complexes. Previous research on xenobiotic immobilization was mostly based on the application of $^{14}$ C-labeled contaminants and radiocounting. Several recent studies demonstrated, however, that the evaluation of binding can be better achieved by applying $^{13}$ C-, $^{15}$ N- or $^{19}$ F-labeled xenobiotics in combination with $^{13}$ C-, $^{15}$ N- or $^{19}$ F-NMR spectroscopy. The rationale behind the NMR approach was that any binding-related modification in the initial arrangement of the labeled atoms automatically induced changes in the position of the corresponding signals in the NMR spectra. The delocalization of the signals exhibited a high degree of specificity, indicating whether or not covalent binding had occurred and, if so, what type of covalent bond had been formed. The results obtained confirmed the view that binding of contaminants to soil organic matter has important environmental consequences. In particular, now it is more evident than ever that as a result of binding, (a) the amount of contaminants available to interact with the biota is reduced; (b) the complexed products are less toxic than their parent compounds; and (c) groundwater pollution is reduced because of restricted contaminant mobility.