• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.2
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• pp.171-187
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• 2023

Objectives: Aircraft cabin cleaning work is characterized by being performed within a limited time in a narrow and enclosed space. The objective of this study was to evaluate the exposure levels to dust, ultra fine dust(PM2.5) and black carbon(BC) among aircraft cabin cleaners. Methods: Active personal air sampling for respirable dust(n=73) and BC(n=47) was conducted during quick transit cleaning(cabin general and vacuum-specific) and seat cover replacement and total dust and PM2.5 were area-air-sampled as well. Also, size distribution of particle was identified with the cleaning workers targeted. Dusts were collected with PVC filters using gravimetric analysis. The concentration of PM2.5 and the particle size distribution were measured with real-time direct reading portable equipment using light scattering analysis. The concentration of BC was measured by aethalometer(filter-based real-time light absorption analysis instrument). Results: The geometric mean of respirable dust was the highest at vacuum cleaning as 74.4 ㎍/m³, following by replacing seat covers as 49.3 ㎍/m³ and cabin general cleaning as 47.8 ㎍/m³ . The arithmetic mean of PM2.5 was 4.83 ~ 9.89 ㎍/m³ inside the cabin, and 28.5~44.5 ㎍/m³ outside the cabin(from bus and outdoor waiting space). From size distribution, PM_2.5/PM₁₀ ratio was 0.54 at quick transit cleaning and 0.41 at replacing seat covers. The average concentration of BC was 2~7 ㎍/m³, showing a high correlation with the PM2.5 concentration. Conclusions: The hazards concentration levels of aircraft cabin cleaners were very similar to those of roadside outdoor workers. As the main source of pollution is estimated to be diesel vehicles operating at airports, and it is necessary to replace older vehicles, strengthen pollutant emission control regulations, and introduce electric vehicles. In addition, it is necessary to provide as part of airport-inftastructure a stable standby waiting space for aircraft cabin cleaners and introduce a systematic safety and health management system for all workers in the aviation industry.

• Korean Journal of Environmental Agriculture
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• v.41 no.4
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• pp.230-235
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• 2022

BACKGROUND: Ammonia gas emitted from nitrogen fertilizers applied in agricultural land is an environmental pollutant that catalyzes the formation of fine particulate matter (PM2.5). A significant portion (12-18%) of nitrogen fertilizer input for crop cultivation is emitted to the atmosphere as ammonia gas, a loss form of nitrogen fertilizer in agricultural land. The widely practiced method for fertilizer use in agricultural fields involves spraying the fertilizers on the surface of farmlands and mixing those with the soils through such means as rotary work. To test the potential reduction of ammonia emission by nitrogen fertilizers from the soil surface, we have added N, P, and K at 2 g each to the glass greenhouse soil, and the ammonia emission was analyzed. METHODS AND RESULTS: The treatment consisted of non-fertilization, surface spray (conventional fertilization), and soil depth spray at 10, 15, 20, 25, and 30 cm. Ammonia was collected using a self-manufactured vertical wind tunnel chamber, and it was quantified by the indophenol-blue method. As a result of analyzing ammonia emission after fertilizer treatments by soil depth, ammonia was emitted by the surface spray treatment immediately after spraying the fertilizer in the paddy soil, with no ammonia emission occurring at a soil depth of 10 cm to 30 cm. In the upland soil, ammonia was emitted by the surface spray treatment after 2 days of treatment, and there was no ammonia emission at a soil depth of 15 cm to 30 cm. Lettuce and Chinese cabbage treated with fertilizer at depths of 20 cm and 30 cm showed increases of fresh weight and nutrient and potassium contents. CONCLUSION(S): In conclusion, rather than the current fertilization method of spraying and mixing the fertilizers on the soil surface, deep placement of the nitrogen fertilizer in the soil at 10 cm or more in paddy fields and 15 cm or more in upland fields was considered as a better fertilization method to reduce ammonia emission.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.619-628
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• 2023

In this study, we investigated the feasibility of calcium sulfate fertilizer as a stabilizing agent for As and Hg contaminated farmland soil and its stabilization characteristics in 3 different physical forms (particulate, powder, and solution) through a pot experiment including 34 days of lettuce growth. As and Hg contents of the lettuce grown in the stabilized soils were decreased by at least 70%. However the lettuce yield of the soil stabilized with the solution agent was decreased by 46% due to the overabundance of the nutrients from the solution agent. Thus, if a solution-type agent is planned for agricultural farmland soil stabilization, additional tests for optimal dosage are needed to preserve vegetation growth. In Hg fractionation, a lower concentration of elemental fractions and a higher concentration of residual/sulfide fractions were identified in the soils stabilized with the solution, powder, and pariculate agents in descending order while there were no significant changes in As fractionation. Overall results suggest that calcium sulfate fertilizer can be used as a stabilizing agent, and a solution-type agent could be used when the operation of heavy machinery for the soil stabilization process is impossible.

• Journal of Korea Port Economic Association
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• v.39 no.3
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• pp.107-122
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• 2023

This study aims to analyze the effect of reducing air pollutant emissions of the ship fuel oil sulfur content regulation policy, which has been gradually introduced for three years. In addition, the emission reduction effect of VSR and AMP was also analyzed. The analysis was conducted on NOx, CO, VOC, SOx, TSP, PM10, and PM2.5, which are provided by EEA, and the spatial scope of the analysis was conducted on Incheon Port, which is located in the metropolitan area of Korea and has a large ripple effect on air pollution. Three scenarios were constructed for analysis. Scenario 1: If there is no policy, Scenario 2: If only fuel oil sulfur content regulation was implemented, Scenario 3: The analysis was conducted by reflecting fuel oil sulfur content regulation, VSR, and AMP. As a result of the analysis, in the case of scenario 1, 4,801 tons, 4,932 tons, and 5,144 tons of air pollutants were emitted during the three-year period. In Scenario 2, 4,219 tons, 4,152 tons, and 3,989 tons were discharged, and in Scenario 3, 4,198 tons, 4,138 tons, and 3,973 tons were discharged. The findings of this study are anticipated to be applied as fundamental research in port air environment management and Incheon Metropolitan City air management.

• Journal of Nutrition and Health
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• v.56 no.6
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• pp.615-628
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• 2023

Purpose: Increasing levels of domestic fine dust (DFD) have emerged as a serious problem that threatens public health by causing chronic respiratory diseases and skin aging. The present study was performed to investigate the inhibitory effects of Gryllus bimaculatus (the two-spotted cricket), which has recently attracted attention as an edible insect in South Korea, on DFD-induced aging and inflammation. Methods: To verify that DFD causes skin aging and investigate the anti-aging effect of an aqueous ethanolic-Gryllus bimaculatus extract (AE-GBE), human diploid fibroblasts (HDF) were treated with 100 ㎍/mL of European reference material (ERM)-CZ100 dust for 24 hrs in the presence or absence of 100 ㎍/ml AE-GBE. Aging and cellular toxicities were assessed by measuring reactive oxygen species (ROS) levels, DNA fragmentation, and β-galactosidase activity. The protein levels of cyclooxygenase (COX) 2, matrix metalloproteinase (MMP)-1, and collagen were measured by western blot, and the mRNA expressions of inflammation-related genes were assayed by quantitative reverse transcriptase polymerase chain reaction. Results: Treatment with ERM-CZ100 induced an aged phenotype in HDF cells, as evidenced by increased ROS levels, DNA fragmentation, and senescence-associated β-galactosidase activity, but cotreatment with AE-GBE significantly reduced these inductions. The mRNA expressions of pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α, induced by ERM-CZ100 were also reduced by AE-GBE cotreatment, which also reduced COX2 expression. Moreover, ERM-CZ100-induced MMP-1 expression and reduced collagen type I expression were recovered by AE-GBE treatment. Conclusion: These results suggest that AE-GBE is a potential treatment for domestic fine dust-induced skin inflammation and inflammaging.

• Journal of Environmental Health Sciences
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• v.50 no.1
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• pp.6-15
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• 2024

Background: People's activities have been restricted due to the COVID-19 pandemic. These changes in activity patterns may lead to a decrease in fine particulate matter (PM_2.5) concentrations. Additionally, the level of population exposure to PM_2.5 may be changed. Objectives: This study aimed to analyze the impact of population movement and meteorological factors on the distribution of PM_2.5 concentrations before and after the outbreak of COVID-19. Methods: The study area was Guro-gu in Seoul. The research period was selected as January to March 2020, a period of significant population movement changes caused by COVID-19. The evaluation of the dynamic population was conducted by calculating the absolute difference in population numbers between consecutive hours and comparing them to determine the daily average. Ambient PM_2.5 concentrations were estimated for each grid using ordinary kriging in Python. For the population exposure assessment, the population-weighted average concentration was calculated by determining the indoor to outdoor population for each grid and applying the indoor to outdoor ratio to the ambient PM_2.5 concentration. To assess the factors influencing changes in the ambient PM_2.5 concentration, a statistical analysis was conducted, incorporating population mobility and meteorological factors. Results: Through statistical analysis, the correlation between ambient PM_2.5 concentration and population movement was positive on both weekends and weekdays (r=0.71, r=0.266). The results confirmed that most of the relationships were positive, suggesting that a decrease in human activity can lead to a decrease in PM_2.5 concentrations. In addition, when population-weighted concentration averages were calculated and the exposure level of the population group was compared before and after the COVID-19 outbreak, the proportion of people exceeding the air quality standard decreased by approximately 15.5%. Conclusions: Human activities can impact ambient concentrations of PM_2.5, potentially altering the levels of PM_2.5 exposure in the population.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.1
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• pp.56-62
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• 2009

Stable carbon isotope analysis was used to investigate the autotrophic carbon sources supporting fisheries in three coastal bay systems of the southern coast of Korea. Carbon isotope ratios (${\delta}^{13}C$) of 31 fish species were analysed and compared with those of a range of potential primary food sources [e.g., seagrass (Zostera marina), seagrass epiphytes, benthic microalgae, macroalgae, marine particulate organic matter (marine POM), marsh plant (Phragmites australis) and terrestrial POM]. ${\delta}^{13}C$ values (range, -16.2${\sim}$-8.3‰) of fishes from the coastal embayment systems were overlapped with those of seagrass (-8.3${\pm}$1.9‰), seagrass epiphytes (-12.4${\pm}$0.6‰), benthic microalgae (-15.4${\pm}$1.6‰) and macroalgae (-16.0${\pm}$1.8‰). In addition, fishes (-12.9${\pm}$1.5‰) from the study area had distinctly higher ${\delta}^{13}C$ values compared to those collected in offshore sites (-17.3${\pm}$0.8‰) of the southern sea of Korea and Nakdong River (-23.2${\pm}$1.6‰). This result indicates that carbon supporting fish communities of these coastal bay systems is mainly derived from the local benthic producers.

• Journal of The Korean Association For Science Education
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• v.26 no.3
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• pp.367-375
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• 2006

This study investigated the effects of varying visuals in drawing and writing as methods to assist students in connecting and integrating multiple external representations provided in learning the particulate nature of matter. Seventh graders (N=233) at a coed middle school were assigned to control, static drawing (SO), dynamic drawing (DD), static writing (SW), and dynamic writing (DW) groups. The students were taught about "Boyle's Law" and "Charles's Law" for two class periods. Two-way ANCOVA results revealed that the scores of a conception test for the two drawing (SD, DD) groups and the two writing (SW, DW) groups were significantly higher than those for the control group. Within the writing groups, students of lower spatial visualization ability in the DW group scored significantly higher than those in the SW group. However, no significant differences were found in the scores of the conception test for the two drawing (SD, DD) groups regardless of students' visualization ability. Researchers also found that most students in both DD and DW groups had respectively positive perceptions of dynamic visuals in drawing or writing.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.29 no.1
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• pp.1-13
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• 2024

The southwestern part of the East Sea is known to have a high primary productivity compared to those in the northern and eastern parts, which is attributed to nutrients supplies either by Tsushima Warm Current or by coastal upwelling. However, research on the biological pump in this area is limited. We developed machine learning models to estimate net community production (NCP), a measure of biological pump, with high spatial and time scales of 4 km and 8 days, respectively. The models were fed with the input parameters of sea surface temperature, chlorophyll-a, mixed layer depths, and photosynthetically active radiation and trained with observed NCP derived from high resolution measurements of surface O₂/Ar. The root mean square error between the predicted values by the best performing machine model and the observed NCP was 6 mmol O₂ m^-2 d^-1, corresponding to 15% of the average of observed NCP. The NCP in the central part of the Ulleung Basin was highest in March at 49 mmol O₂ m^-2 d^-1 and lowest in June and July at 18 mmol O₂ m^-2 d^-1. These seasonal variations were similar to the vertical nitrate flux based on the ³He gas exchange rate and to the particulate organic carbon flux estimated by the ²³⁴Th disequilibrium method. To expand this method, which produces NCP estimate for spring and summer, to autumn and winter, it is necessary to devise a way to correct bias in NCP by the entrainment of subsurface waters during the seasons.

• Particle and aerosol research
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• v.19 no.4
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• pp.129-144
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• 2023

The PM_1.0 and PM_2.5 samples were collected synchronously using a single channel particulate sampler equipped with PM_1.0 and PM_2.5 cyclones, respectively, and seasonal mass concentration and chemical composition of PM_1.0 and PM_2.5 were quantified in Seoul and Gwangju in 2021-2022. The mass concentrations of PM_1.0 and PM_2.5 were 17±11 and 22±14 ㎍/m³ in Seoul, and 16±9 and 19±12 ㎍/m³ in Gwangju, respectively. The average ratios of PM_1.0/PM_2.5 were 83±16% in Seoul and 83±7% in Gwangju. The chemical compositions of PM_1.0 and PM_2.5 were similar at both sites with OC component being the most dominant, and NO₃^- increasing from summer to winter, while, the difference of chemical distribution at the two sites was most distinct in the autumn. Gwangju showed a higher proportion of OC and a lower proportion of NO₃^- compared to Seoul during the autumn. Both sites appear to reflect their urban characteristics, with Gwangju also reflecting the impact of biomass combustion as a part of rural activities.