• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.45-47
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• 2017

The Infrared Camera onboard the AKARI satellite carried out spectroscopic observations with a grism mode named NG, whose wavelength coverage was $2.5-5.0{\mu}m$. We reinvestigate the current flux calibration for the NG grism mode, with which calculated flux density implausibly decreases at $4.9{\mu}m$ especially for red objects due to the second-order light contamination. We perform a new spectral response calibration using blue and red standard objects simultaneously. New response curves which contain both the first-and second-order light are able to separate each contribution consistently and useful for studies of red objects such as CO ro-vibrational absorption in active galactic nuclei.

• Journal of Environmental Health Sciences
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• v.27 no.1
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• pp.44-50
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• 2001

This study was carried out to investigate characteristics of water quality and THMs formation in lake-waters at kunsan. Of the parameters examined for water quality, pH, alkalinity, SO$_4$$^{-2}$ and Co- reflected the characteristics according to the origin, geography and water source of lakes while COD, SS, T-P, T-N and chlorophyll-a corelatively reflected well the influence of pollution factors around factors around lakes. The result of water quality analysis showed that most lakes in Kunsan area have the severe eutropnication problem, especially in summer. In lake-waters, THMFP overally continued to increase until 48 hour with the reaction time and THMs formation was largely achieved within 24 hour of the reaction time. The average formation ratio were 68.2% for CHCl$_3$, 23.6% for CHCl$_2$Br, 7.6% for CHClBr$_3$ and 0.6% for CHBr$_3$respectively and much difference depending on the reaction time was not shown. Overally, 96h-THEFP levels in lakes were high during June~September and showed higher tencency in lakes where could be regarded more contaminated on the whole. These results suggest that THMFP may be available for the management of lake-water quality as one if the useful parameters for the general evaluation of contamination. 96h-THEMFP failed to show the strong corelation individually with pH, TOC, COD and chlorphyll-a.

• ALGAE
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• v.20 no.2
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• pp.157-166
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• 2005

Uptake kinetics of Cd and Zn by leaves and rhizome of the seagrass Zostera marina were examined in controlled laboratory radiotracer experiments. Subsequently, acute toxicity of Cd, Cu and TBT on photosynthetic quantum yield (ΔF/Fm’ of Z. marina were determined, and the differential sensitivities of rapid light curve (RLC) to those harmful substances were also compared. All measurements on photosynthetic activity were determined by chlorophyll a fluorescence method using pulse amplitude modulation (PAM). Metal uptake by Z. marina was saturated with increasing exposure time in leaves and rhizomes. Uptake of Zn by Z. marina was faster than that of Cd. Metal uptake rates in Z. marina decreased with the increase of dissolved metal concentrations and also with the increase of biomass. The adverse effect of TBT on effective quantum yield was stronger than other pollutants. Average acute toxicity on the RLC of the seagrass exposed to TBT and two heavy metals (Cd and Cu) was going to decrease as follows: TBT > Cd > Cu. Our preliminary results in this study suggested that Z. marina potentially can be used as a biomonitor of harmful substances contamination in coastal waters.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.347-350
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• 2002

Arsenic speciation changes between As(V) and As(III) are subject to changes in accordance with redox conditions in the environment. It is common to find contaminated sites associated with mixed wastes including both organic pollutants and heavy metals. We conducted microcosm experiment under hypothesis that the co-disposed organic pollutants would influence on the arsenic forms and concentrations, via degradation of the organic pollutants and the consequent impact on the redox conditions in soil. Artificially contaminated soil samples were run for 40 days with control samples without artificial contamination. We noticed arsenic in the contaminated soil showed different behaviour compared with the arsenic in the control soil. The findings indicate degradation of organic pollutants in the contaminated soil influenced on the arsenic speciation and concentrations. A further work is needed to understand the process quantitatively. However, we could confirm that degradation of organic pollutants can influence on the abiotic processes associated with geochemical reactions in contaminated soil. Degradation of organic pollutants can increase the mobility and toxicity of arsenic in soil and sediment by changing redox conditions in the geological media and subsequently from As(V) to As(III).

• Journal of the Korean Society of Safety
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• v.29 no.6
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• pp.40-45
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• 2014

In display such as LCD, LED, and AMOLED or semiconductor related industries are required to have static ionizer in order to produce reliable goods. The most general type of ionization is called, "corona discharge" that has a slight chances to generate unequal and unstable amount of each +/- ion to the target object. Then, the ionization performance will drastically decrease and end up with quality deterioration problem. continually "A study on the improvement of the performance of pulsed AC ion bar(1)", we have studied consecutive study to improve the current issue via appling "partition wall" at air nozzle surrounding. The results were that the charge decay time and the ion balance was maintained the satisfied range that was within 5 second and ${\pm}50$ V for a 180 days period of time. In additions, the contamination status on the electrode surface was investigated for a 180 days. The little particles was deposited on the electrode surface.

• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.101-113
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• 2016

To properly manage and remediate groundwater contaminated with chlorinated hydrocarbons such as trichloroethylene (TCE), it is necessary to assess natural attenuation processes of contaminants in the aquifer along with investigation of contamination history and aquifer characterization. This study evaluated natural attenuation processes of TCE at an industrial site in Korea by delineating hydrogeochemical characteristics along the flow path of contaminated groundwater, by calculating reaction rate constants for TCE and its degradation products, and by using geochemical and reactive transport modeling. The monitoring data showed that TCE tended to be transformed to cis-1,2-dichloroethene (cis-1,2-DCE) and further to vinyl chloride (VC) via microbial reductive dechlorination, although the degree was not too significant. According to our modeling results, the temporal and spatial distribution of the TCE plume suggested the dominant role of biodegradation in attenuation processes. This study can provide a useful method for assessing natural attenuation processes in the aquifer contaminated with chlorinated hydrocarbons and can be applied to other sites with similar hydrological, microbiological, and geochemical settings.

• The Plant Pathology Journal
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• v.36 no.5
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• pp.509-514
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• 2020

Satsuma dwarf virus (SDV) seriously damages citrus production by reducing the quality and yield of fruit. To avoid contamination with SDV, mother trees are checked to be SDV-free in advance of nursery tree distribution. In this study, we compared an immunochromatographic assay (ICA) kit with double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) for large-scale diagnosis of SDV in orchardgrown trees in Shizuoka Prefecture, Japan. The two methods gave conflicting results for 11 of 1,705 samples, all of which were negative by DAS-ELISA but positive by ICA. The samples scored as positive by either DAS-ELISA or ICA were analyzed by reverse transcription polymerase chain reaction and all were confirmed to be positive. These results validate the use of ICA as a screening method for large-scale diagnosis. Strain discrimination revealed that 16 of 22 isolates belonged to SDV, while citrus mosaic virus (CiMV) infection only and co-infection (SDV and CiMV) were in a minority.

• Environmental Analysis Health and Toxicology
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• v.23 no.3
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• pp.143-164
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• 2008

Concern about perfluorinated compounds (PFCs) is growing nationally as well as globally. PFCs could be considered emerging POPs due to their environmentally persistent, bioaccumulative, and potentially harmful properties. Moreover. perfluoroalkylates (PFAs) such as PFOS and PFOA are reported to experience long-range transport (LRT) to the Arctic in spite of their low volatility and strong solubility. The possible pathways contributing to LRT have been proposed but are still in debate in combination with unclear source definition and uncertain physico-chemical properties. The environmental fate of PFCs is more complicated because of the presence of precursors that are degraded to PFAs and are extremely different from their daughters, PFAs. in physico-chemical properties. To what extent and through what pathways are human and wildlife exposed is determined by the environmental fate and distribution of PFCs. To define uncertainties in fate and distribution thus is critical to prevent erroneous policy and/or determination related with exposure and risk reduction. This article aimed to review controversy and/or uncertain issues for the environmental fate and distribution of PFCs and to prospect research topics necessary to dissolve uncertainties.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.334-337
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• 2004

Groundwater chemistry in Namwon area, Korea, was investigated to understand the contribution of geochemical processes on groundwater chemistry. For this study, a total of 279 groundwater samples were collected from 93 wells distributed over the study area. Higher concentrations of major ions are generally encountered in the shallow alluvial wells, suggesting that these chemicals are originated from the surface contamination sources. Mass balance analysis based on reaction stoichiometry reveals that the water chemistry is regulated by three major chemical processes: weathering of silicate/ carbonate minerals, input of C1/SO$_4$ salts, and nitrate generating processes. The results show that mineral weathering is the most dominating factor regulating the groundwater chemistry. However, the groundwaters with the higher salt concentration indicate the larger mineral weathering effect, suggesting that some part of the mineral weathering effect is also associated with the anthropogenic activities such as limes applied to the cultivated lands, carbonates (CaCO$_3$) in the cement materials.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.8 s.227
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• pp.1183-1189
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• 2004

A novel cell count method, which can improve the count efficiency and reduce contamination problem, was presented using micro lattice engraved on culture dish. The micro lattice has feature of $50{\mu}m{\times}50{\mu}m$ rectangular shape, $2{\mu}m$ line width, and $2{\mu}m$ depth in $3mm{\times}3mm$ area. In this paper, nickel mold was fabricated with thickness of 3mm and diameter of 80 mm, and transcription of the micro lattice on a polystyrene cell culture dish was performed by hot embossing at $200\;^{\circ}C$. The tedious and error-prone harvest/load processes of conventional cell counts with a hemocytometer could be omitted, and these advantages became magnified during periodical counts involving long-term cultures. SupT1 cells and HeLa cells were cultivated with the dish for 7 days in $CO_2$ incubator and counted as $371.84/mm^2$ and $123.36/mm^2$, respectively, during the cultivation without harmful effects on the cells.