• Journal of agricultural medicine and community health
• /
• v.46 no.3
• /
• pp.131-143
• /
• 2021

Objectives: This study aimed 1) to investigate high school students' reliability on COVID-19 responses in schools and private academies and 2) to identify the differences in COVID-19 prevention practice. Methods: This cross-sectional survey collected data from 200 high school respondents, using an anonymous online questionnaire designed by the Yonsei Global Health Center, from July 2 to 17, 2020 in this study. Chi-square tests were conducted to analyze the differences in preventative practices and practice rates between schools and private academies. Binary logistics regression analysis was conducted to identify the factor affecting the reliability of COVID-19 response. Results: These high school students reliabilityed the schools' COVID-19 response more than the private academy. In addition, students who studied only at school did more COVID-19 prevention practices than students who studied both at school and academy. There was a significant difference in avoiding public transportation (p=.028), sitting in one row while having a meal (p=.011) in the practice rates depending on the schools' COVID-19 response. A significant difference in Covering the mouth when coughing and sneezing (p-.041) was also found in the practice rates depending on the private academies' COVID-19 response. Conclusion: The reason why schools were more reliable than private academies was that there are health teachers. Because schools are supervised by the ministry of education, the Ministry of education and local government need to work together to manage and monitor the COVID-19 response in the academies through cooperation between two organizations. In addition, it is necessary to arrange a temporary circulation health teacher who will provide the COVID-19 prevention education at the academies.

• Korean Journal of Food Science and Technology
• /
• v.53 no.4
• /
• pp.470-478
• /
• 2021

This study was conducted to monitor residual pesticides in a total of 527 school foodservice agricultural products from 2019 to 2020 in Incheon. Pesticide residues in the samples were analyzed by the multi-residue method in the Korean food code for 373 pesticides using GC-MS/MS, LC-MS/MS, GC-ECD, GC-NPD, and HPLC-UVD. By monitoring the pesticides, 12 (2.3%) of the 527 pesticides were detected, and 2 (0.4%) samples exceeded the maximum residue limit. Twelve types of pesticides were detected in the agricultural products of carrot, chard, chili pepper, chwinamul, crown daisy, parsley, perilla leaves, and spinach. As a means of risk assessment through the consumption of agricultural products detected with pesticide residues, the proportion of estimated daily intake to acceptable daily intake was estimated in the range of 0.0000-39.7425%. Results showed no particular health risk through the consumption of school foodservice agricultural products with pesticide residues.

• Korean Journal of Remote Sensing
• /
• v.37 no.6_1
• /
• pp.1657-1667
• /
• 2021

Anthropogenic activities and natural processes have been causes of land subsidence which is sudden sinking or gradual settlement of the earth's solid surface. Mexico City, the capital of Mexico, is one of the most severe land subsidence areas which are resulted from excessive groundwater extraction. Because groundwater is the primary water resource occupies almost 70% of total water usage in the city. Traditional terrestrial observations like the Global Navigation Satellite System (GNSS) or leveling survey have been preferred to measure land subsidence accurately. Although the GNSS observations have highly accurate information of the surfaces' displacement with a very high temporal resolution, it has often been limited due to its sparse spatial resolution and highly time-consuming and high cost. However, space-based synthetic aperture radar (SAR) interferometry has been widely used as a powerful tool to monitor surfaces' displacement with high spatial resolution and high accuracy from mm to cm-scale, regardless of day-or-night and weather conditions. In this paper, advanced interferometric approaches have been applied to get a time-series of land subsidence of Mexico City using four-year-long twenty ALOS PALSAR L-band observations acquired from Feb-11, 2007 to Feb-22, 2011. We utilized persistent scatterer interferometry (PSI) and small baseline subset (SBAS) techniques to suppress atmospheric artifacts and topography errors. The results show that the maximum subsidence rates of the PSI and SBAS method were -29.5 cm/year and -27.0 cm/year, respectively. In addition, we discuss the different subsidence rates where the study area is discriminated into three districts according to distinctive geotechnical characteristics. The significant subsidence rate occurred in the lacustrine sediments with higher compressibility than harder bedrock.

• Korean Journal of Remote Sensing
• /
• v.37 no.6_1
• /
• pp.1739-1756
• /
• 2021

Atmospheric nitrogen dioxide (NO₂) is mainly caused by anthropogenic emissions. It contributes to the formation of secondary pollutants and ozone through chemical reactions, and adversely affects human health. Although ground stations to monitor NO₂ concentrations in real time are operated in Korea, they have a limitation that it is difficult to analyze the spatial distribution of NO₂ concentrations, especially over the areas with no stations. Therefore, this study conducted a comparative experiment of spatial interpolation of NO₂ concentrations based on two linear-regression methods(i.e., multi linear regression (MLR), and regression kriging (RK)), and two machine learning approaches (i.e., random forest (RF), and support vector regression (SVR)) for the year of 2020. Four approaches were compared using leave-one-out-cross validation (LOOCV). The daily LOOCV results showed that MLR, RK, and SVR produced the average daily index of agreement (IOA) of 0.57, which was higher than that of RF (0.50). The average daily normalized root mean square error of RK was 0.9483%, which was slightly lower than those of the other models. MLR, RK and SVR showed similar seasonal distribution patterns, and the dynamic range of the resultant NO₂ concentrations from these three models was similar while that from RF was relatively small. The multivariate linear regression approaches are expected to be a promising method for spatial interpolation of ground-level NO₂ concentrations and other parameters in urban areas.

• Korean Journal of Remote Sensing
• /
• v.37 no.6_1
• /
• pp.1767-1772
• /
• 2021

Global satellite observation surface albedo data over a long period of time are actively used to monitor changes in the global climate and environment, and their utilization and importance are great. Through the generational shift of geostationary satellites COMS (Communication, Ocean and Meteorological Satellite)/MI (Meteorological Imager sensor) and GK-2A (GEO-KOMPSAT-2A)/AMI (Advanced Meteorological Imager sensor), it is possible to continuously secure surface albedo outputs. However, the surface albedo outputs of COMS/MI and GK-2A/AMI differ between outputs due to Differences in retrieval algorithms. Therefore, in order to expand the retrieval period of the surface albedo of COMS/MI and GK-2A/AMI to secure continuous climate change monitoring linkage, the analysis of the two satellite outputs and errors should be preceded. In this study, error characteristics were analyzed by performing comparative analysis with ground observation data AERONET (Aerosol Robotic Network) and other satellite data GLASS (Global Land Surface Satellite) for the overlapping period of COMS/MI and GK-2A/AMI surface albedo data. As a result of error analysis, it was confirmed that the RMSE of COMS/MI was 0.043, higher than the RMSE of GK-2A/AMI, 0.015. In addition, compared to other satellite (GLASS) data, the RMSE of COMS/MI was 0.029, slightly lower than that of GK-2A/AMI 0.038. When understanding these error characteristics and using COMS/MI and GK-2A/AMI's surface albedo data, it will be possible to actively utilize them for long-term climate change monitoring.

• The Korean Journal of Medicine
• /
• v.93 no.6
• /
• pp.538-547
• /
• 2018

Background/Aims: The impact of left ventricular (LV) diastolic function and filling pressure on clinical outcomes in young patients with acute myocardial infarction (AMI) has been poorly studied. Therefore, the aim of this study was to investigate the impact of LV diastolic function and LV filling pressure on major adverse cardiac events (MACEs) in young patients with AMI. Methods: A total of 200 young patients (males < 45 year, females < 55 year) with AMI were divided into two groups according to the diastolic function; normal (n = 46, $39.5{\pm}5.3$ years) versus abnormal (n = 154, $43.5{\pm}5.1$ years). Results: Despite regional wall motion abnormalities, normal LV diastolic function was not uncommon in young AMI patients (23.0%). During the 40 months of clinical follow-up, MACEs developed in 26 patients (13.0%); 14 re-percutaneous coronary intervention (7.0%), 8 recurrent MI (4.0%), and 4 deaths (2.0%). MACEs did not differ between the normal and abnormal diastolic function group (13.6% vs. 10.9%, p = 0.810), but MACEs were significantly higher in the high LV filling pressure group than the normal LV filling pressure group (36.8% vs. 10.5%, p < 0.001). On multivariate analysis, high LV filling pressure was an independent predictor of MACEs (hazard ratio 3.022, 95% confidence interval 1.200-7.612, p = 0.019). Conclusions: This study suggested that measurement of the LV filling pressure (E/e' ratio) would be useful in the risk stratification of young patients with AMI. However, it would be necessary to monitor this category of patient more carefully.

• Korean Journal of Environmental Agriculture
• /
• v.37 no.4
• /
• pp.302-311
• /
• 2018

BACKGROUND: Dithianon (75%) formulation were mixed and sprayed as closely as possible by normal practice on the ten farms located in the Mungeong of South Korea. Patches, cotton gloves, socks, masks, and XAD-2 resin were used for measurement of the potential exposure of dithianon on the applicators wearing standardized whole-body outer and inner dosimeter (WBD). This study has been carried out to determine the dermal and inhalation exposure to dithianon during preparation of spray suspension and application with a power sprayer on a apple orchard. METHODS AND RESULTS: A personal air monitor equipped with an air pump, IOM sampler and cassette, and glass fiber filter was used for inhalation exposure. The field studies were carried out in a apple orchard. The temperature and relative humidity were monitored with a thermometer and a hygrometer. Wind speed was measured using a pocket weather meter. All mean field fortification recoveries were between 85.1% and 99.1% in the level of 100 LOQ (limit of quantification), while the LOQ for dithianon was $0.05{\mu}g/mL$ using HPLC-DAD. The exposure to dithianon on arms of the mixer/loader (0.0794 mg) was higher than other body parts (head, hands, upper body, or legs). The exposure to dithianon on the applicator's legs (3.78 mg) was highest in the body parts. The dermal exposures for mixer/loader and applicator were 10 and 8.10 mg, respectively, from a grape orchard. The inhalation exposure during application was estimated as 0.151 mg, and the ratio of inhalation exposure was 11.2% of the dermal exposure (inner clothes). CONCLUSION: The dermal and inhalation exposure on the applicator appeared to be 4.203 mg - 25.064 mg and $0.529{\mu}g-116.241{\mu}g$, respectively. The total exposures on the agricultural applicators were at the level of 2.596 mg - 25.069 mg to dithianon during treatment for apple orchard. The TER showed 3.421 (>1) when AOEL of dithianon was used as a reference dose for the purpose of risk assessment of the mixing/loading and application.

• Journal of Climate Change Research
• /
• v.4 no.4
• /
• pp.305-316
• /
• 2013

The purpose of this study is to monitor the flux of $CO_2$ between the atmosphere and forest. The main research activities are conducted at Taehwa Mt. (Gangju, Kyeonggi, Korea), The Taehwa site is located 60 km north-east from the center of Seoul Metropolitan Area. The TRF flux tower is in the middle of a Korean Pine (Pinus koraiensis) plantation ($400m{\times}400m$), surrounded by a mixed forest. Eddy covariance method was used for $CO_2$ flux above the forest. $CO_2$ flux was measured from September to November 2011 and March to June 2012. It was found that $CO_2$ fluxes were observed between the atmosphere and forest. $CO_2$ was absorbed by plants through photosynthesis during the day and released during the night. $CO_2$ flux were respectively observed 0.7~0.2, 0.5~0.1, $0.3{\sim}0.1mgCO_2m^{-2}s^{-1}$ in Septem- ber, October, November 2011. $CO_2$ fluxes released by plants in the early morning(00:00~07:30h) and evening(18:00~24:00h) time. But $CO_2$ was absorbed by plants through photosynthesis in the day time(08:00~7:30h).

• Korean Journal of Remote Sensing
• /
• v.34 no.6_1
• /
• pp.1041-1053
• /
• 2018

In this study, a real-time storage level and capacity monitoring and forecasting system for Yongdam Dam watershed was developed using high resolution satellite image. The drought indices such as Standardized Precipitation Index (SPI) from satellite data were used for storage level monitoring in case of drought. Moreover, to predict storage volume we used a statistical method based on Principle Component Analysis (PCA) of Singular Spectrum Analysis (SSA). According to this study, correlation coefficient between storage level and SPI (3) was highly calculated with CC=0.78, and the monitoring and predictability of storage level was diagnosed using the drought index calculated from satellite data. As a result of analysis of principal component analysis by SSA, correlation between SPI (3) and each Reconstructed Components (RCs) data were highly correlated with CC=0.87 to 0.99. And also, the correlations of RC data with Normalized Water Surface Level (N-W.S.L.) were confirmed that has highly correlated with CC=0.83 to 0.97. In terms of high resolution satellite image we developed a water detection algorithm by applying an exponential method to monitor the change of storage level by using Multi-Spectral Instrument (MSI) sensor of Sentinel-2 satellite. The materials of satellite image for water surface area detection in Yongdam dam watershed was considered from 2016 to 2018, respectively. Based on this, we proposed the possibility of real-time drought monitoring system using high resolution water surface area detection by Sentinel-2 satellite image. The results of this study can be applied to estimate of the reservoir volume calculated from various satellite observations, which can be used for monitoring and estimating hydrological droughts in an unmeasured area.

• Journal of Korean Society of Forest Science
• /
• v.107 no.4
• /
• pp.351-360
• /
• 2018

This study was conducted to analyze the responses of chlorophyll contents and growth of Pinus densiflora and Quercus variabilis seedlings on distance from the well and $CO_2$ flux after the artificial $CO_2$ release. From June 1 to 30, 2016, $CO_2$ gas was injected at the rate of $6L\;min^{-1}$ at the study site in Eumseong. Chlorophyll content was analyzed in the middle of July, 2016, and root collar diameter (RCD), height (H), and biomass were measured in May and December, 2016 after planting 2-year-old P. densiflora and 1-year-old Q. variabilis seedlings in May, 2015. The chlorophyll content of P. densiflora seedlings did not show a significant correlation with $CO_2$ flux, whereas the chlorophyll content of Q. variabilis seedlings showed a significant negative correlation with increasing $CO_2$ flux (P<0.05). The RCD and H growth rates of both species showed the significant difference in the distance from the well of the $CO_2$ anthropogenic release treatment. In particular, the RCD and H growth rate of P. densiflora seedlings and the RCD growth rate of Q. variabilis seedlings increased significantly as the seedlings were closer to the well, but the H growth rate of Q. variabilis seedlings decreased significantly. In addition, as the $CO_2$ concentration in the ground increases, ${\Delta}R/S$ ratio increases in both species, suggesting that the high $CO_2$ concentration in the soil promotes carbon distribution relative to the root part. The results of this study can be used as data necessary to monitor the $CO_2$ leakage and physiological and growth responses of both species to leakage of stored $CO_2$ in the future.