• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.387-392
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• 2007

In this study performance evaluation of filtering system were made on the clean air supply system to show it's ability to eliminate the air contaminants. The evaluation was conducted inside the 3,200CMH scale wind tunnel and under the same environment that is effected by yellow dust and similar particle and gas phase contaminants in semi-conductor and FPDs industries. (1) The result of experimental for particle contaminants, the particle removing efficiency was 40% on condition that the air velocity is 2.5m/s, L/G ratio : 0.05, electrified voltage : (+)5.8kV with electric charger and (-)3.5kV with eliminator. (2) The gas phase removing efficiency for $NH_3$ : 80%, $SO_X$ : 70% and $NO_X$ : 40% on condition that the air velocity is 2.5m/s, L/G ratio : 0.05.

• Corrosion Science and Technology
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• v.5 no.1
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• pp.27-32
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• 2006

One of the critical issues in the coating specification is the allowable limit of surface contaminant(s) - such as soluble salt(s), grit dust, and rust - after grit blasting. Yet, there is no universally accepted data supporting the relationship between the long-term coating performance and the amount of various surface contaminants allowed after grit blasting. In this study, it was attempted to prepare epoxy coatings applied on grit-blasted steel substrate dosed with controlled amount of surface contaminants - such as soluble salt(s), grit dust, and rust. Then, coating samples were subjected to 4,200 hours of cyclic test(NORSOK M-501), which were then evaluated in terms of resistance to rust creepage, blistering, chalking, rusting, cracking and adhesion strength. Additional investigations on the possible damage at the paint/steel interface were carried out using an Electrochemical Impedance Spectroscopy(EIS) and observations of under-film-corrosion. Test results suggested that the current industrial specifications were well matched with the allowable degree of rust, whereas the allowable amount of soluble salt and grit dust after grit blasting showed a certain deviation from the specifications currently employed for fabrication of marine vessels and offshore facilities.

• The Journal of the Korea Contents Association
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• v.16 no.5
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• pp.660-667
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• 2016

Conventional decontamination methods utilize water-based systems, which generate high amounts of secondary wastes. Herein, we describe an environmentally benign decontamination method using liquid and supercritical $CO_2$. The use of $CO_2$ as a solvent affords effective waste reduction by its ability to be recycled, thereby leaving be hind only the contaminants upon its evaporation. In this study, a $CO_2$ solution process was assessed using t-salen(t-butylsalen), DC18C6 (dicyclohexano-18Crown6), 8-HQN(8-hydroxyquinoline), NEt4PFOSA(perfluoro-1-octanesulfonic acid tetra-ethyl ammonium salt), and NEt4PFOA(pentadecafluorooctanoic acid ammonium salt) to extract spiked radioactive contaminants(Nb,Zr,Co,Sr) from an inert sample matrix, namely filter paper. With the static extraction method, Sr was extracted with a maximum extraction rate of 97%, and Nb was extracted with a maximum extraction rate of 75%. Additionally, we were also able to extract Co and Zr with maximum extract ion ratesof 73% and 64%, respectively.

• 한국초전도학회:학술대회논문집
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• v.15
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• pp.7-7
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• 2005

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.02a
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• pp.106-113
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• 2004

A major problem of nuclear energy is the production of radioactive wastes. Needs for more environmentally favorable method to decontaminate radioactive contaminants make the use of liquid/Supercritical $CO_2$ as a solvent medium. In removing radioactive metallic contaminants under $CO_2$ solvent, two methods - use of chelating ligands and that of water in $CO_2$ emulsion - are possible. In the chelating ligand method, a combination of ligands that can make synergistic effects seems important. We discuss about the properties of microemulsion formed by F-AOT. By adding acid in water core, decontamination of metallic parts, soils were possible.

• Advances in environmental research
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• v.4 no.3
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• pp.143-153
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• 2015

The ventilation system is a key device to ensure both healthful indoor air quality (IAQ) and thermal comfort in buildings. The ventilation system should make the IAQ meet the standards such as ASHRAE 62. This study deals with a new approach to modeling the ventilation and IAQ requirement in residential buildings. In that approach, Elite software is used to calculate the air supply volume, and CONTAM model as a multi-zone and contaminant dispersal model is employed to estimate the contaminants' concentrations. Amongst various contaminants existing in the residential buildings, two main contaminates of carbon dioxide ($CO_2$) and carbon monoxide (CO) were considered. CO and $CO_2$ are generated mainly from combustion sources such as gas cooking and heating oven. In addition to the mentioned sources, $CO_2$ is generated from occupants' respirations. To show how that approach works, a sample house with the area of $80m^2$ located in Tehran was considered as an illustrative case study. The results showed that $CO_2$ concentration in the winter was higher than the acceptable level. Therefore, the air change rate (ACH) of 4.2 was required to lower the $CO_2$ concentration below the air quality threshold in the living room, and in the bedrooms, the rate of ventilation volume should be 11.2 ACH.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.257-257
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• 2015

Carbon Capture and Storage with ocean sequestration is being considered as one of the most effective option for reducing the $CO_2$ net flux from atmosphere nowadays. But it is still possible for $CO_2$ substance to leaks out from transport pipeline or from the under seabed storage sites and causing damage to ambient environment. The behavior of liquid $CO_2$ under droplet shape would be strongly affected by the presence of other contaminants such as $SO_2$ comes from processing processes. This presentation shows the behavior in the sea water of pure liquid $CO_2$ droplets as well as droplets that consist of $SO_2$ substances. The study uses computational fluid dynamic models in comparison with experimental data from other previous researchers. Droplet of liquid $CO_2$ is assumed to be released at several depths in deep ocean, with other environmental conditions are set up respectively. All calculations are conducted with many different ratio of contaminant $SO_2$ to provide fundamental data of those particles rising characteristics. The effect of contaminants on the behavior of $CO_2$ droplets would be clearly shown through the results of particle deformation, terminal rising velocity happen due to buoyancy force driving from the difference in density of $CO_2$ substance and ocean water around.

• Korean Journal of Veterinary Service
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• v.31 no.4
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• pp.547-554
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• 2008

Bacteriospermia is a frequent finding in fresh boar semen and can result in detrimental effects on semen quality and longevity. The objectives of this study was to evaluate types of bacterial contaminants in porcine fresh semen and the reducing effect of antibiotic and density gradient with percoll on the bacterial contaminants. Fresh semen was collected by gloved-hand method into a pre-warmed($37^{\circ}C$) thermostable bottle, and was inoculated onto blood agar and MacConkey agar, respectively. After incubated for 48 hour, 7.5% $CO_2$ at $37^{\circ}C$, bacterial colonies were selected and identified by Gram staining, oxidase test, catalase test and finally identified using API kits and Vitek system. Aerobic culture yielded a variety of bacteria from different genera. The most prevalent contaminant of fresh semen were Leclecia adecarboxylata, Acineobacter banmanni, Staphylococcus epidermidis, Staphylococcus cohni spp urealyticus, Proteus mirabilis. Most of identified bacteria were Gram(-) and non-pathogenic bacteria. It seems that bacterial contaminants in fresh semen were seem originated from multiple sources at the stud/farm, and were from animal and non-animal origins. Gentamicin treatment did not eliminate the bacterial contaminants completely but 3 step-density gradient with percoll completely removed the bacterial contaminants in fresh semen. Therefore, future study is necessary to prove that density gradient method with percoll can eliminate bacteria in fresh semen without significantly affecting sperm viability or function.

• Journal of Soil and Groundwater Environment
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• v.21 no.5
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• pp.1-7
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• 2016

The removal of non-aqueous phase liquids (NAPLs) from groundwater using pure water, via pump and treat, is quite ineffective due to their low solubility and hydrophobicity. Therefore, the objectives of pilot tests were to select potentially suitable surfactants that solubilize tetrachloroethylene (PCE) and trichloroethylene (TCE) present as contaminants and to evaluate the optimal range of process parameters that can increase the removal efficiency in surfactant-enhanced soil flushing (SESF). Used experimental method for surfactant selection was batch experiments. The surfactant solution parameters for SESF pilot tests were surfactant solution concentration, surfactant solution pH, and the flow rate of surfactant solution in the SESF pilot system. Based on the batch experiments for surfactant selection, DOSL (an anionic surfactant) was selected as a suitable surfactant that solubilizes PCE and TCE present as contaminants. The highest recovery (95%) of the contaminants was obtained using a DOSL surfactant in the batch experiments. The pilot test results revealed that the optimum conditions were achieved with a surfactant solution concentration of 4% (v/v), a surfactant solution pH of 7.5, and a flow rate of 30 L/min of surfactant solution (Lee and Woo, 2015). The maximum removal of contaminants (89%) was obtained when optimum conditions were simultaneously met in pilot-scale SESF operations. These results confirm the viability of SESF for treating PCE and TCE-contaminated groundwater.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.650-654
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• 2003

A major problem of nuclear energy is the production of radioactive wastes. Needs for more environmentally favorable method to decontaminate radioactive contaminants make the use of liqui $d^ercritical $CO_2$ as a solvent medium. In removing radioactive metallic contaminants under $CO_2$ solvent, two methods - use of chelating ligands and that of water in $CO_2$ emulsion-are possible. In the chelating ligand method, a combination of ligands that can make synergistic effects seems important. We discuss about the properties of microemulsion formed by F-AOT and that by non-ionic surfactant. By adding acid in water core, decontamination of metallic parts, soils were possible. The rate of metal surface dissolution to the microemulsion solution was measured by QCM. The possibility of recovering the surfactants after use is also mentioned.ed.