• Journal of Environmental Health Sciences
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• v.38 no.3
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• pp.213-222
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• 2012

Objectives: This study was undertaken in order to evaluate by work space zoning and structure the concentrations of biological contaminants in the indoor air of domestic office buildings. Methods: Air samples were collected in the office spaces of 15 office buildings in Seoul from June 28 to July 28, 2011. Prior to the sampling, each office was classified into 'open-plan office', 'cellular office' and 'mixed office' according to the work space zoning. To evaluate the biological contamination of indoor air, total suspended bacteria (TSB), Gram positive bacteria (GPB), Staphylococcus aureus (S.A), Methicillin-resistant Staphylococcus aureus (MRSA), Gram negative bacteria (GNB) and fungi were investigated. During the sampling, temperature, relative humidity and carbon dioxide ($CO_2$) were measured. Results: The TSB concentrations ($GM{\pm}GSD$) were $452({\pm}1.3)cfu/m^3$ in open-plan offices, $366({\pm}1.3)cfu/m^3$ in cellular offices and $287({\pm}1.5)cfu/m^3$ in mixed offices, and there were significant differences between the three groups (p<0.05). The highest concentrations ($GM{\pm}GSD$) of fungi were found in the indoor air of cellular offices $128({\pm}1.0)cfu/m^3$, which was at least three times higher than the concentrations in mixed offices $43({\pm}1.0)cfu/m^3$ (p<0.05). Conclusions: Microbiological contamination in the indoor air of office buildings by work space structure was the highest with the open-plan office layout which includes no high walls or doors separating the occupants.

• Journal of the Korean Geosynthetics Society
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• v.8 no.3
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• pp.35-44
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• 2009

The purpose of this study was to prevent spreading of contaminants from movement of underground water by creating a barrier using artificial freezing method on a soil contaminated by oils and various NAPLs. Specimens with 80% and 90% degrees of saturation were prepared to form freezing barrier using artificial freezing method. With increasing freezing time of freezing barrier, barrier was formed faster in the specimen with 90% degree of saturation by about an hour compared to the specimen with 80% degree of saturation. In addition, thinnest thickness of frozen barrier in both specimens was 50mm after 12 hours of freezing time, showing expansion of freezing area with time. The results of this study can be applied to barrier in waste reclamation sites and contaminated regions or to flow control of contaminants.

• Bulletin of the Korean Chemical Society
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• v.35 no.12
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• pp.3475-3481
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• 2014

This paper describes how primary contaminants in ambient air affect the performance of the cathode in fuel cell electric vehicle applications. The effect of four atmospheric pollutants ($SO_2$, $NH_3$, $NO_2$, and CO) on cathode performance was investigated by air impurity injection and recovery test under load. Electrochemical analysis via polarization and electrochemical impedance spectroscopy was performed for various concentrations of contaminants during the impurity test in order to determine the origins of performance decay. The variation in cell voltage derived empirically in this study and data reported in the literature were normalized and juxtaposed to elucidate the relationship between impurity concentration and performance. Mechanisms of cathode degradation by air impurities were discussed in light of the findings.

• Horticultural Science & Technology
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• v.33 no.4
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• pp.550-558
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• 2015

To analyze the linkage relationships among molecular markers recently reported to be linked to onion (Allium cepa L.) Ms, a restorer-of-fertility locus, in onion (Allium cepa L.), three single nucleotide polymorphism markers were converted into cleaved amplified polymorphic sequence (CAPS) markers based on onion transcriptome sequences and the rice genome database. Analysis of the recombinants selected from 4,273 segregating plants using CAPS and other linked markers demonstrated the jnurf13 and jnurf610 markers to perfectly co-segregate with the Ms locus. In contrast to jnurf13, the jnurf610 marker was not in perfect linkage disequilibrium with the Ms locus in diverse breeding lines. Thus, the jnurf13 marker and the marker for identification of cytoplasm types were utilized to enhance the efficiency of onion breeding through four applications. First, 89 maintainer lines containing the normal cytoplasm and homozygous recessive Ms genotypes were successfully identified from 100 breeding lines. Second, these two molecular markers were used to analyze the main sources of male-fertile contaminants frequently found in the male-sterile parental lines during F1 hybrid seed production. The majority of the contaminants contained heterozygous Ms genotypes, indicating that pollen grains harboring the dominant Ms genotype may have been introduced during propagation of the maintainer lines. Therefore, the genetic purity of the two maintainer lines was analyzed in the third application, and the results showed that both maintainer lines contained 13-21% off-types. Finally, the two markers were used to increase the seed yield potentials of two open-pollinated varieties containing sterile cytoplasms by removing the plants harboring homozygous recessive and heterozygous Ms genotypes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1754-1759
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• 2010

Because the stone cultural properties located outdoors, they have been altered and deteriorated in external appearance due to environmental factors such as acid rain, extreme change in temperature, and salts. Damage to stone cultural properties is accelerated particularly due to recent industrial development and environmental pollution. An experimental study was conducted to evaluate the effect of environmental contaminants(sea water and air pollutants such as, $SO_2$, NO, $CO_2$) on the weathering of granite. And as part of the developing of conservation method, $TiO_2$ catalyst was prepared and tested. After expose a granite to sea water and air pollutants, the mineral compositions of the tested granite surface were lower then that of the fresh granite. And absorption capacity of the weathered granite was steadily increased. From these results, it was expected that granite could be weathered by sea water and air pollutants. For the $TiO_2$ coated granite, absorption capacity was slightly enhanced compared to the $TiO_2$ non-coated granite. Therefore, the $TiO_2$ coating method tested in this study considered to be a viable method to assist in the conservation of granite from environmental contaminants.

• Journal of Korean Society on Water Environment
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• v.22 no.1
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• pp.23-29
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• 2006

Biosorption technology was used to remove hazardous materials from wastewater, herbicide, heavy metals, and radioactive compounds, based on binding capacities of various biological materials. Biosorption process can be explained by two steps; the first step is that target contaminants is in contact with microorganisms and the second is that the adsorbed target contaminants is infiltrated with inner cell through metabolically mediated or physico-chemical pathways of uptake. Until recently, no information is available to explain the definitive mechanism of biosorption. The purpose of this study is to evaluate biosorption capabilities of organic matters using activated sludge and to investigate affecting factors upon biosorption. Over 49% of organic matter could be removed by positive biosorption reaction under anoxic condition within 10 minutes. The biosorption capacities were constant at around 50 mg-COD/mg-MLSS for all batch experiments. As starvation time increased under aerobic or anaerobic conditions, biosorption capacity increased since higher stressed microorganisms by starvation was more brisk. Starvation stress of microorganisms was higher at aerobic condition than anaerobic one. As temperature increased or easily biodegradable carbon sources were used, biosorption capacities increased. Consequently, biosorption can be estimated by biological -adsorbed capability of the bacterial cell-wall and we can achieve the cost-effective and non -residual denitrification with applying biosorption to the bio-reduction of nitrate.

• Journal of Soil and Groundwater Environment
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• v.27 no.spc
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• pp.92-98
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• 2022

Although various methods have been proposed to assess groundwater vulnerability, most of the models merely consider the mobility of contaminants (i.e., intrinsic vulnerability), and the attenuation capacity of vadose zone is often neglected. This study proposed an evaluation model for the attenuation capacity of vadose zone to supplement the limitations of the existing index method models for assessing groundwater vulnerability. The evaluation equation for quantifying the attenuation capacity was developed from the combined linear regression and weighted scaling methods based on the lab-scale experiments using various vadose zone soils having different physical and biogeochemical properties. The proposed semi-quantifying model is expected to effectively assess the attenuation capacity of vadose zone by identifying the main influencing factors as input parameters together with proper weights derived from the coefficients of the regression results. The subsequent scoring and grading system has great versatility while securing the objectivity by effectively incorporating the experimental results.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.5
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• pp.702-707
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• 1999

A percoll density gradient technique was developed for producing high quality turkey semen and improving the fertility by removing deleterious cellular components, including spermiophages, bacteria, abnormal or dead spermatozoa, and other cellular debris. The combination of three different percoll densities, 1.05, 1.07, and 1.08 showed the best resolution and was selected to prepare a discontinuous percoll density gradient to obtain healthy spermatozoa from semen smples. Bacteria, spermiophages, and abnormal or dead spermatozoa were detected from the density range from 1.05, 1.05 to 1.07, and 1.07 to 1.08, respectively. Healthy spermatozoa were collected from the density greater than 1.08. Spermatozoa obtained from percoll density gradient centrifugation showed better sperm motility than those from unprocessed pooled semen. Bacteria including Escherichia coli, Staphylococcus aureus, and Proteus spp., were predominant contaminants in turkey semen, and the numbers of cells were approximately $5{\times}10^5$ to $1{\times}10^9cfu/ml$. The overall fertility rates in hens inseminated with processed percoll density gradient were higher than those in hens with unprocessed semen especially for unhealthy sperm. In conclusion, semen quality can be improved by percoll density gradient centrifugation, which augmented the fertility of turkey breeders.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.10
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• pp.697-703
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• 2010

In recent semiconductor manufacturing clean rooms, air washers are used to remove airborne gaseous contaminants from the outdoor air introduced into a clean room. Meanwhile, there is a large amount of exhaust air from a clean room. From an energy conservation point of view, heat recovery is useful for reducing the outdoor air conditioning load required to maintain a clean room. Therefore it is desirable to recover heat from the exhaust air and use it to cool or heat the outdoor air. In the present study, numerical analysis was conducted to evaluate the recovered heat of an exhaust air heat recovery type air washer system, which is the key part of an energy saving outdoor air conditioning system for semiconductor clean rooms. The present numerical results showed relatively good agreement with the available experimental data.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2000.06a
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• pp.34-39
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• 2000

Today's size of production operations in the packaging paper sector I sconstantly increasing , featuring integral processing systems, high-speed paper machines, and the increased marketing of lower basis weight products. The risk factors involved in these large investments lie more than ever in the available furnish potential and ongoing requirements for further closure of water loops and lower operating costs. A comparison is drawn between recovered paper furnish mixtures used in European mills with regard to fibre properties, strength potential and contaminant content, Both the furnish situation and development trends in modern fluting and testliner machines are instigating concept changes in stock preparation, the approach flow as well as in process water and rejects technology. Developments are currently focussed for example on more efficient debris separation using fine slotted screening, optimized refining , more systematic process water management with loop separation and integral water clarification as well as more efficient removal of microstickies, fillers and fines through appropriate combination of rejects handling and water clarification processes. Product quality differentiation depends decisively on strength characteristics as a function of refining , fines removal , paper machine technology, and sizing . Maximum availability of today's high speed paper machines and , as a result, cost effective production can be ensured by optimum balancing of all subsystems with in the overall concept and by reliable control of problems with contaminants and deposits.