• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.4
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• pp.159-168
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• 2015

Forty-four surface sediments from Doam Bay were analyzed for total organic carbon (TOC), total nitrogen (TN), total metal (Al, Fe, Mn, Cr, Cu, Ni, Pb, Zn) and further chemical partitioning of metals were carried out in some samples. The TOC (0.32~3.10%) and TN (0.03~0.26%) values of the samples were similar to those of other coastal area. The C/N ratios ranged from 7.9 to 11.9 with an average 9.3 which revealed that contribution of terrestrial organic matters was relatively rare. Contents of analysed metals showed a level lower than threshold effects level (TEL) in sediment quality guidelines. Based on the chemical speciation of metals, the lattice fractions were found in the order Cr > Cu > Ni > Zn > Pb > Mn, while Mn and Pb are the ratio of the non-lattice fractions accounted for more than 50%. The average baseline values were obtained relative cumulative frequency curves and linear regression analysis. The respective baseline concentrations for Cu, Ni, Pb, Zn, Cr and Mn were 11.8, 23.1, 26.8, 76.6, 56.7, 585 mg/kg, respectively. Based on geoaccumulation index ($I_{geo}$) with a baseline values of Mn showed that face the contamination phase from estuarine stations. However, in case of Zn and Pb, although there is no sign of contamination, it could be release from sediment when there is a change in the environment, which is caused from the high ratio of non-lattice fractions.

• Food Science and Preservation
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• v.12 no.4
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• pp.317-322
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• 2005

The purposes of this study were to assess the microbiological contamination level of various disposable kitchen utensils and evaluate the effectiveness of gamma irradiation as a sterilization process for the utensils. The 51 kinds in 17 groups of disposable kitchen utensils were tested for the enumeration of total aerobic plate count, coliforms, fungi and Salmonella. Generally, cell density of microorganisms in disposable kitchen utensils were lower than that of cooking utensils currently using in kitchen. The survivals of total aerobic plate counts, putrefactive bacteria, on the surface of the disposable utensils were ranged up to $10^3\;CFU/100\;cm^2$. Filamentous fungi were detected in 13 samples. Coliform bacteria were detected in two kinds of samples but Salmonella spp. was detected below detection limits in all the samples. The microorganisms survived on the surface of utensils were effectively eliminated by gamma irradiation process at 3 kGy.

• Journal of Environmental Science International
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• v.33 no.4
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• pp.269-277
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• 2024

Scientific forensic techniques are used to verify environmental impact of groundwater pollution, surface water pollution, air pollution, noise, and vibration according to residents' complaints in connection with construction and civil engineering works. In this study, we investigated the contamination of groundwater and the lowering of the groundwater level in an area surrounding a tunnel excavation site for the Andong-Yeongdeok national road, using a forensic hydrogeological technique. We reviewed the groundwater level and water quality of well GW1 in the area surrounding the tunnel excavation site as well as tunnel construction information and then we analyzed the correlations among the obtained data. Before tunnel excavation, the water level of well GW1 was lower than the tunnel elevation. Considering the relationship between the precipitation, tunnel discharge, tunnel depth, and groundwater level of well GW1, the groundwater flowed from the tunnel to well GW1. Moreover, the tunnel discharge and groundwater levels were not related to each other. The pH of well GW1 was 8.4 before tunnel excavation. During excavation, the pH declined to 8.1-8.2 at the beginning, and increased to 8.8 at the end of the excavation. The fluorine concentration in well GW1 was 2.49 mg/L, 1.91-3.22 mg/L, and 1.7-2.67 mg/L, respectively, before, during, and after the excavation. The sulfate ion concentration was very high, over 2,000 mg/L, before and during the excavation; after the excavation, it was between 200 and 323 mg/L. Turbidity was 1.47, 10.5, and 4.51 NTU before, during, and after tunnel excavation, respectively. Therefore, the excavation of this tunnel is not related to the groundwater quality of well GW1.

• Journal of the Semiconductor & Display Technology
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• v.22 no.3
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• pp.130-135
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• 2023

Plasma-resistant ceramic (PRC) is a material used to prevent internal damage in plasma processing equipment for semiconductors and displays. The challenge is to suppress particles falling off from damaged surfaces and increase retention time in order to improve productivity and introduce the latest miniaturization process. Here, we confirmed the effect of suppressing plasma deterioration and reducing the etch rate through surface treatment of existing PRC with an initial illumination level of 200 nm. In particular, quartz glass showed a decrease in etch rate of up to 10%. Furthermore, it is believed that micro-scale secondary particles formed on the microstructure of each material grow as crystals during the fluoridation process. This is a factor that can act as a killer defect when dropped, and is an essential consideration when analyzing plasma resistance. The plasma etching suppression effect of the initial illumination is thought to be due to partial over etching at the dihedral angle of the material due to the sputtering of re-emission of Ar+-based cations. This means that plasma damage due to densification can also be interpreted in existing PRC studies. The research results are significant in that they present surface treatment conditions that can be directly applied to existing PRC for mass production and a new perspective to analyze plasma resistance in addition to simple etching rates.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.397-400
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• 2007

For mapping the distribution of heavy metals in the mining area, field spectroscopy and hyperspectral remote sensing were used in this study. Although heavy metals are spectrally featureless from the visible to the short wave infrared range, possible variations in spectral signal due to heavy metals bound onto minerals can be explained with the metal binding reaction onto the mineral surface. Variations in the spectral absorption shapes of lattice OH and oxygen on the mineral surface due to the combination of heavy metals were surveyed over the range from 420 to 2400 nm. Spectral parameters such as peak ratio and peak area were derived and statistically linked to metal concentration levels in the streambed samples collected from the dry stream channels. The spatial relationships between spectral parameters and concentrations of heavy metals were yielded as well. Based on the observation at a ground level for the relationship between spectral signal and metal concentration levels, the spectral parameters were classified in a hyperspectral image and the spatial distribution patterns of classified pixels were compared with the product of analysis at the ground level. The degree of similarity between ground dataset and image dataset was statistically validated. These techniques are expected to support assessment of dispersion of heavy metal contamination and decision on optimal sampling point.

• Journal of environmental and Sanitary engineering
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• v.8 no.1
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• pp.67-80
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• 1993

This survey was carried out to take the status of seawater intrusion into groundwater wells located in the eastern area of Chejudo, to get the elementary data which may evaluate the level of would-be groundwater contamination, and to perform effective the effort that will supply the clear water for the residents. The sampling sites were northeastern districts of Haengwon, Handong, and Sangdo, southeastern districts of Susan, Nansan, and Samdal, and northwestern districts, as reference, of Aewol, Keumnung, Panpo, Kosan, Shindo, and Bosung. We collected the samples from the public tap water by month, and analysed electrical conductivity, sodium(Na), potassium(K), magnesium(Mg), calcium(Ca), bicarbonate($HC0_{3^-}$), and items of the criteria as drinking water. In the northeastern districts we also added the sampling sites to survey the fluctuations of dissolved solids according to distance from seashore, including two private boreholes and one public tap water of Dukchun. The result is as follows 1) In the northeastern district, the concentration of chloride ion showed large fluctations from 40mg/l to 100mg/l, but suitable for the criteria of drinking water. It was thought that the drought influenced. 2) In the Sangdo of the northeastern districts, similar tendancy to Hangwon and Handong was showed only in the concentration of chloride ion, but different tendancy was showed in chloride-bicarbonate ratio, calcium-magnesium ratio, and sodium adsorption ratio(SAR). Considering these facts, it was not thought that seawater intruded. 3) The components of Na and Cl showed rapid slope in the northeastern districts above 3km from seashore. 4) In the northwestern districts as reference, the concentration of chloride ion fluctuated slightly according to the sampling sites and dates, and the concentration of nitrate-nitrogen in some sites exceeded the criteria of drinking water. These were thought that the surface contaminants rather than the intrusion of seawater influenced mainly the groundwater, considering the correlation(r=0.732) of chloride ion and nitrate-nitrogen. 5) Then we must consider the regional characteristies of soil profile in order to prevent the contamination of groundwater, and moniter also the movement of main components within the sol1 profile, not only the research of the intrusion of seawater.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.1
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• pp.46-52
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• 2008

Oils and chlorinated solvents leaking to the subsurface are entrapped in the soil pore and these are called as nonaqueous phase liquids (NAPL). NAPL entrapped in porous media acts as a continuous source for surface and ground water contamination. This study visualized dissolution of trichloroethylene (TCE) entrapped in porous media and quantified the velocity of TCE dissolution using an image analysis technique. As the water velocity increased, the level of dissolution increased. The results imply that a TCE contaminated region having a high infiltration rate and groundwater velocity may result in severe groundwater contamination. Microscopic images of TCE entrapped in porous media showed that TCE present in the preferential flow paths was easily dissoluted into the water phase. However, TCE present in the stagnant flow region was visualized for long time. The results imply that TCE would be still present in the soil if TCE is detected in goundwater.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.522-525
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• 2003

Mine waters, surface waters and groundwaters were sampled around seven Au-Ag mine areas (Dongil, Okdong, Dongjung, Songcheon, Ssangjeon, Dogok and Gubong Au-Ag mines). The main contamination sources of As in these abandoned Au-Ag mines can be suggested as mine tailings and waste rocks including the sulfide gangue minerals (arsenopyrite). The relatively high concentration of As in mine waters was shown in the Dongil (524 ${\mu}g/L$) and the Dogok (56 ${\mu}g/L$) mine areas. Arsenic concentrations in stream waters from the Dongil ($0.9\~118{\mu}g/L$), the Songchon ($0.8\~63{\mu}g/L$), the Ssangjeon ($1.6\~109{\mu}g/L$) and the Gubong ($3.6\~63{\mu}g/L$) mine areas exceeded the permissible level for stream water in Korea. Groundwaters collected from the Dongil ($0.9\~64{\mu}g/L$ ), the Okdong ($0.2\~69{\mu}g/L$) and the Gubong ($0.5\~101{\mu}g/L$) mine areas contained high As concentration to cause the arsenicosis in these areas. In As speciation, the concentration ratios of As(III) to As(total) present up to $75\%$ and $100\%$ in stream waters from the Okdong and the Songcheon mines, and $70\%$ in groundwaters from the Okdong and the Dongjung mines. Arsenic concentration decreases downstream from the tailing dump correlatively with pH and Fe concentration. Highly elevated As concentrations are found in the dry season (such as April and March) than in the wet season (September) due to the dilution effect by heavy rain during summer in stream waters from the Dongil and the Songcheon mine areas.

• Korean Journal of Veterinary Service
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• v.36 no.3
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• pp.157-162
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• 2013

A good level of biosecurity practice is important for efficient porcine reproductive and respiratory syndrome (PRRS) control. In the current study, disinfecting ability of ozone against PRRS virus (PRRSV) was evaluated in comparison with ultraviolet (UV) and an organic acid-based disinfectant to assess the possible use of ozone for disinfecting farm vehicles, equipments, and materials to reduce the risk of new virus introduction. For in vitro evaluation, the levels of infectious virus and viral RNA were determined on the swabs collected from the floor surface of each room treated with either ozone, UV or the disinfectant up to 30 min after contamination with 100 mL of VR2332 ($10^5\;TCID_{50}/mL$). For in vivo evaluation, 3, 4-week old, PRRS-free pigs were housed into those rooms right after the last swab collection. Then the pigs in each room were injected intramuscularly with the corresponding swab samples collected at the last time point and pooled per each room. Although ozone, UV, and the disinfectant significantly reduced the levels of PRRSV RNA contamination, ozone was most effective in removing the viral RNA. In addition, the virus collected after at least 10 min exposure to ozone failed to replicate in pigs while the virus collected after treatment with UV and the disinfectant for 30 min still replicated in pigs. Based on the results, it was concluded that ozone is more effective in inactivating PRRSV as compared with UV and the organic acid-based disinfectant.

• Journal of the Korean Dietetic Association
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• v.28 no.3
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• pp.205-217
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• 2022

School meals are prepared based using the HACCP system, which is designed to ensure the physical and mental health of students. However, operational recommendations in school cafeterias have changed due to COVID-19 and include delays in serving time to restrict the number of meals and the installation of screens to prevent droplet transmission. Unfortunately, these changes may have detrimentally affected hygiene practices and generated new food poisoning sources. This study aimed to determine the hygiene state of school cafeterias in the Gyeongnam area from December 2020 to September 2021 based on the monitoring of total aerobic and coliform bacteria. Kitchen floors were the most contaminated areas with an average number of total aerobic bacteria of 4.3 log CFU/100 cm², whereas counts in dining areas were relatively low at 0.1~3.5 log CFU/100 cm². Newly installed partitioned areas had the lowest contamination level of 0.1~2.8 log CFU/100 cm². Escherichia coli was not detected on any surface, while coliform was detected on workbenches and floors. In conclusion, hygienic practices appear to have been adequately managed in school cafeterias despite COVID-19 driven changes. Nonetheless, continuous monitoring is recommended to ensure prompt response to changing environments.