• Journal of the korean society of oceanography
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• v.33 no.4
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• pp.178-184
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• 1998

To elucidate contamination levels and distribution of methyl mercury (Me-Hg) in Korean coastal areas, 126 sediment samples were collected from Kyeonggi Bay, Namyang Bay, Chinhae Bay, and Lake Shihwa during 1995-1996, and the Me-Hg concentrations were determined by cold vapor atomic fluorescence spectrometry (CVAFS). Contamination levels of Me-Hg in sediments from Kyeonggi Bay, Namyang Bay, Chinhae Bay, and Lake Shihwa were 274 ${\pm}$ 990, 108 ${\pm}$ 24, 294 ${\pm}$ 342, and 1080 ${\pm}$ 760 pg/g, respectively. Concentrations of Me-Hg in sediments were significantly correlated with total organic carbon and sulfur contents, but were independent of mud contents and mean grain size. The highest concentration of Me-Hg (7100 pg/g) was observed at Incheon North Harbor (Site Kl9) in Kyeonggi Bay. This Me-Hg concentration was one or two orders of magnitude higher than those in other Kyeonggi Bay sediments were. The average concentration of Me-Hg in sediments from Lake Shihwa was higher than in those from other study areas. The three peaks of Me-Hg concentrations were observed on three sites (55, 56,and 510) in Lake Shihwa and gradually decreased in distance-dependent manner around these sites. High concentrations of Me-Hg at surface and 10-cm sediment depth in Chinhae Bay maybe due to higher rates of methylation process by active sulfate-reducing bacteria or higher concentrations of total mercury available to sulfate-reducing bacteria.

• Journal of Korea Soil Environment Society
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• v.4 no.2
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• pp.163-174
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• 1999

This paper presents a case history of remedial action adopted for contaminated groundwater in a landfill. The objectives of the projects are : (1) to effectively confine contaminated groundwater with an economically reasonable means, (2) to prevent further contamination of soil by collecting and treat the contaminant. and (3) to assure the environmental safety of the landfill during its operating period. Reported are the process from site investigation, through design and construction of an appropriate remedial action, to the monitoring of the selected confinement system. In view of the results of site investigation, deep soil mixing cutoff wall using the DMW(deep soil mixing cutoff wall) method and specially produced HEC soil stabilizer were used for the construction of deep soil mixing cutoff wall. For rock foundation with sever fractures, chemical grout curtain with urethane was installed. The monitoring results to date indicate that the selected vertical barrier performed satisfactorily.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.26 no.1
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• pp.41-58
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• 2000

Recently the harmfulness of W radiation is in creasing due to encironmental pollution. Environmental population may also play a role in global decrease of ozone layer, A major consequence of ozone depletion is increase in solar ultra violet radiation received at the earth's surface excessive exposure to W radiation cause a lot of problems in our skin. Plant extract that possess antioxidative activities has been reported to retard the oxidation process in product to which they have been added. Plant are alived under solar light. So it is expect the plants have so many protection mechanisms and UV absorbent ingredients against ultra violet radiation such as UVB, UVA. Plant extract which were flavonoids, alkaloids and others could be transformed into UV absorber by chemical modification. Therefore with the aim of finding alternative natural absorber that can safely be used in cosmetic, we have screened various extract for their UV absorbent effect. Thus, the cosmetic safety against human skin, antimicrobial effects and others could be improved by using the silicon.

• Food Science and Industry
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• v.53 no.3
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• pp.277-283
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• 2020

Microbial disinfection is essential to increase the preservation and safety of food. In general, thermal sterilization technology is most frequently used, but it often causes nutrient denaturation, and deterioration of food quality. Accordingly, non-thermal sterilization using a novel technology is emerging as an alternative technology. Among them, ultrasonic technology produces a disinfection effect by promoting the destruction of microorganisms by cavitation. Ultrasound technology alone has a low effect, so research is being actively conducted to develop an effective technology by applying as a hurdle technology with various other technologies. Ultrasound can be treated with various processes including traditional sterilization methods such as heating, high pressure, and chemical treatment, as well as novel technologies such as ultraviolet irradiation. Ultrasound assisted sterilization technology still remains at the laboratory level, requiring additional research such as the development of equipment for industrial application and establishment of an optimal process.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.1
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• pp.1-9
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• 2022

Objectives: The purpose of this study is to evaluate exposure characteristics of lead using data from the domestic occupational exposure literature. Methods: Occupational airborne exposure data on lead reported in the domestic literature from 1981 to 2018 were collected and re-analyzed. The exposure levels in the data were expressed as an estimated arithmetic mean and a weighted arithmetic mean (WAM) of the number of samples. Lead exposure characteristics were analyzed by industry, process, and year. Results: From a total of 14 documents, 8,305 airborne lead measurements for 17 industries were identified, and the WAM concentration in eight industries exceeded the occupational exposure limit of 50 ㎍/m³. Three industries (battery manufacturing, lead smelting, and litharge manufacturing) accounted for 95% of the total data, and exposure trends could be confirmed over 10 years. Exposure levels continue to decrease in all three industries. Conclusions: Considering the distribution outlook of lead and lead compounds, the main management targets are lead storage battery manufacturing and secondary smelting for lead regeneration.

• Journal of the Korean Society of Food Culture
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• v.38 no.4
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• pp.191-202
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• 2023

Food upcycling has emerged as an effective approach to sustainably utilize the food waste generated within the food supply chain. This review article examines upcycled food with respect to its definition, consumers' knowledge and perception on it, and the process by which by-products from the food supply chain are utilized for the creation of upcycled food products. The definition of upcycled food varied among manufacturers, research institutions, and the Upcycled Food Association, depending on the specific values and objectives of each sector. This has resulted in the use of different keywords to highlight the distinctive characteristics of their respective interpretations of upcycled food. This review also summarizes the various consumer traits that can influence the awareness and acceptance of upcycled food, encompassing functional, empirical and emotional, symbolic and self-expressive, and economic benefits. Additionally, the review presents strategies to utilize by-products produced in large quantities in Korea, while also addressing the control of hazardous components to ensure biological or chemical safety and the changes in nutritional value that may occur during the utilization of these byproducts.

• Journal of the Korean Institute of Gas
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• v.27 no.4
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• pp.92-101
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• 2023

To solve the problem of climate change, carbon neutrality has now become a necessity rather than an option. Hydrogen is not only a energy storage that can supplement the intermittent production of renewable energy, but is also considered a good alternative in the field of utilization as it does not emit carbon dioxide after reaction. In order to revitalize hydrogen vehicles, one of the fields of hydrogen utilization, the construction of hydrogen station infrastructure must be preceded. Prioritization of risk factors is necessary for efficient operation and risk assessment of hydrogen stations, but due to the short operation period of domestic hydrogen stations, there is a lack of frequency data on accidents and their reliability is low. In this study, we aim to identify the causes and consequences of deviations in hydrogen stations through HAZOP analysis. Additionally, we intend to analyze them using Fuzzy-AHP. Through this, we intend to derive the decision values for the causes of deviations in hydrogen stations and apply them to hydrogen accident cases and risk assessments to confirm the reliability and utility of the data.

• Clinical Endoscopy
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• v.55 no.1
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• pp.33-40
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• 2022

Background/Aims: Multiple outbreaks of multidrug-resistant organisms have been reported worldwide due to contaminated duodenoscopes. In 2015, the United States Food and Drug Administration recommended the following supplemental enhanced surveillance and reprocessing techniques (ESRT) to improve duodenoscope disinfection: (1) microbiological culture, (2) ethylene oxide sterilization, (3) liquid chemical sterilant processing system, and (4) double high-level disinfection. A systematic review and meta-analysis was performed to assess the impact of ESRT on the contamination rates. Methods: A thorough and systematic search was performed across several databases and conference proceedings from inception until January 2021, and all studies reporting the effectiveness of various ESRTs were identified. The pooled contamination rates of post-ESRT duodenoscopes were estimated using the random effects model. Results: A total of seven studies using various ESRTs were incorporated in the analysis, which included a total of 9,084 post-ESRT duodenoscope cultures. The pooled contamination rate of the post-ESRT duodenoscope was 5% (95% confidence interval [CI]: 2.3%-10.8%, inconsistency index [I²]=97.97%). Pooled contamination rates for high-risk organisms were 0.8% (95% CI: 0.2%-2.7%, I²=94.96). Conclusions: While ESRT may improve the disinfection process, a post-ESRT contamination rate of 5% is not negligible. Ongoing efforts to mitigate the rate of contamination by improving disinfection techniques and innovations in duodenoscope design to improve safety are warranted.

• The Korean Journal of Pesticide Science
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• v.19 no.4
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• pp.370-393
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• 2015

This study was conducted to compare STQ method, multi-residue method in Korean food code and QuEChERS method for validated selected and accuracy, reproducibility and efficiency. A total of 45 selected and targeted pesticides were the analyzed by GC and 5 of them were crops (apple, potato, green pepper, rice, soy bean). $R^2$ values were calculated in the standard calibration curve was over 0.990. Recovery tests were performed by three replications in two levels and the relative standard deviation of the repeated experiments was less than 30%. The average percentage of recoveries in the multi-residue method in Korean food code was 89.13%, QuEChERS method was 92.45% and STQ method was 85.28%. In addition, matrix effects in multi-residue method in Korean food code was 24.61%, QuEChERS method was 23.98% and STQ method showed 11.24%. The STQ method is easy and showed high clean-up effect in extracting the sample solution than the QuEChERS method and clean-up with C18, PLS, PSA cartridge columns. A large volume of the sample was injected in order to compensable for the problem, that occurred due to high detection limit in the analyser. When the STQ method was applied using a large volume injector, the standard calibration curve showed a higher linearity $R^2=0.990$, and method detection limit was 0.01 mg/kg. It showed an average recovery of 91.84% and the relative standard deviations of three replications repeated in two level process was less than 30% and had an average matrix effect of 17.90%.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.169-175
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• 2018

This study deals with a process for the recovery of hydrogen isotopes from methane ($CQ_4$) and water ($Q_2O$) containing tritium in the nuclear fusion exhaust gas (Q is Hydrogen, Deuterium, Tritium). Steam Methane Reforming and Water Gas Shift reactions are used to convert $CQ_4$ and $Q_2O$ to $Q_2$ and the produced $Q_2$ is recovered by the subsequent Pd membrane. In this study, one circulation loop consisting of catalytic reactor, Pd membrane, and circulation pump was applied to recover H components from $CH_4$ and $H_2O$, one of $CQ_4$ and $Q_2O$. The conversion of $CH_4$ and $H_2O$ was measured by varying the catalytic reaction temperature and the circulating flow rate. $CH_4$ conversion was 99% or more at the catalytic reaction temperature of $650^{\circ}C$ and the circulating flow rate of 2.0 L/min. $H_2O$ conversion was 96% or more at the catalytic reaction temperature of $375^{\circ}C$ and the circulating flow rate of 1.8 L/min. In addition, the amount of $CQ_4$ generated by Korean Demonstration Fusion Power Plant (K-DEMO) in the future was predicted. Then, the treatment process for the $CQ_4$ was proposed and HAZOP (hazard and operability) analysis was conducted to identify the risk factors and operation problems of the process.