• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.4
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• pp.362-371
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• 2016

The distribution patterns of Chromophoric Dissolved Organic Matter (CDOM) and the chemical characteristics of CDOM in the Seomjin river estuary were investigated in March, June and July 2012 in order to determine the spatial and temporal variability of CDOM along the salinity gradient considering the effects of mixing, nutrients and Chl a. The average CDOM values were $1.0{\pm}0.3m^{-1}$, $1.3{\pm}0.4m^{-1}$, and $1.4{\pm}0.3m^{-1}$ in March, June and July, respectively. A high concentration of CDOM (greater than $1.5m^{-1}$) was found at the head of the river which decreased towards the river mouth to as low as less than $0.5m^{-1}$. The average concentrations of CDOM increased from the dry season (March and June) to the wet season (July), and the average slope values ($S_{300-500}$), which were used as indicators of CDOM characteristics and sources, were in the range of $0.013-0.018m^{-1}$. The CDOM and $S_{300-50}$ values showed that not only the concentration of CDOM but also the chemical properties of DOM clearly changed between upstream and downstream in the Seomjin river. CDOM and FDOM showed a negative correlation with salinity ($R^2$ > 0.8), and CDOM was positively correlated with FDOM. Furthermore, the mixing pattern of CDOM was confirmed as conservative for all seasons. The main environmental factors influencing the concentration of CDOM was confirmed as conservative for all seasons. The main environmental factors influencing the concentration of CDOM were salinity (mixing) and water temperature, which meant the dilution of low CDOM seawater, was the controlling factor for the spatial distribution of CDOM. Increases in water temperature seemed to induce the production of CDOM during summer (June and July) through the biological degradation of DOM either by microbial activity or photo-degradation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.6
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• pp.708-722
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• 2016

Land-Ocean Interactions in the Coastal Zone (LOICZ) models for nutrient budgets were used to estimate the seasonal capacity of the Youngsan Estuary and Youngam-Geumho Estuary to sink and/or supply nutrients such as dissolved inorganic phosphorus (DIP) and nitrogen (DIN) to provide an understanding of the behavior of the coupled biogeochemical cycles of phosphorus and nitrogen in the estuaries (Youngsan Estuary, Youngam-Geumho Estuary) near Mokpo Harbor. During non-stratified periods (May, September, and November, 2008), simple three-box models were applied in each sub-region of the system, while a two-layer box model was applied during on-site observation of stratification development (July, 2008). The resulting mass-balance calculation indicated that even after large discharges from artificial lakes (in May and July), DIP influxes due to a mixing exchange ($V_{X-3}$, or $V_{deep}$) were more than terrigenous loads, indicating the backward transportation of nutrients from a marine source. The model results also indicated that for nutrient loads (DIP and DIN fluxes) in September, an extreme congestion of nutrients occurred around the mouths (sub-region III of the model) of the estuaries, possibly due to an imbalance in physical circulations between the estuaries and offshore locations. In November, the Youngam-Geumho Estuary, into which freshwater was discharged from artificial lakes (Youngam and Geumho Lake), showed nutrient enrichment in the water column, but the Youngsan Estuary showed nutrient depletion. In conclusion, to efficiently control water quality in the estuaries near Mokpo Harbor, integrated environmental management programs should be implemented. I.e., the reduction of nutrient loads from land basins as well as the deposit of nutrient loads into adjacent coastal lines.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.9
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• pp.970-977
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• 2005

The commercial $V_2O_5-WO_3/TiO_2$ catalysts which had been exposed to the off gas from incinerator for a long time were remanufactured by washing with distilled water and arid solution and reimpregnation with catalytic active components($V_2O_5-WO_3$). The catalytic properties and NOx conversion reactivity of those catalysts were examined by analysis equipment and NOx conversion experiment. Under the experimental condition used in this study, the remanufactured catalysts activated by distilled water ultra sonic cleaning, the catalytic activity was recovered in the range of $66{\sim}93%$ of that of the fresh and the maximum activity was showed when the ultra sonic cleaning time was more than 3 minutes. The remanufactured catalysts by acid solution ultra sonic cleaning, the catalytic activity was recovered in the range of $81{\sim}97%$ of that of the fresh catalyst and the maximum catalytic activity was shooed when the pH of the acid solution was 5. The remanufactured catalysts by reimpregnation with $V_2O_5$ and $WO_3$, the catalytic activity was recovered in the range of $87{\sim}100%$ of that of the fresh catalyst. Maximum catalytic activity was showed when the $V_2O_5$ was reimpregnated more than 1.0 wt %. In this case, the catalytic activity was recovered 97% of that of the fresh catalyst especially at the $150^{\circ}C$ of the experimental temperature.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.4
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• pp.295-302
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• 2014

This study demonstrates a double-path CDI as an alternative of advanced wastewater treatment process. While the CDI typically consists of many pairs of electrodes connected in parallel, the new double-path CDI is designed to have series flow path by dividing the module into two stages. The CFD model showed that the double-path had uniform flow distribution with higher velocity and less dead zone compared with the single-path. However, the double-path was predicted to have higher pressure drop(0.7 bar) compared the single-path (0.4 bar). From the unit cell test, the highest TDS removal efficiencies of single- and double-path were up to 88% and 91%, respectively. The rate of increase in pressure drop with an increase of flow rate was higher in double-path than single-path. At 70 mL/min of flow rate, the pressure drop of double-path was 1.67 bar, which was two times higher than single-path. When the electrode spacing was increased from 100 to $200{\mu}m$, the pressure drop of double-path decreased from 1.67 to 0.87 bar, while there was little difference in TDS removal. When proto type double-path CDI was operated using sewage water, TDS, $NH_4{^+}$-N, $NO_3{^-}$-N and $PO_4{^{3-}}$-P removal efficiencies were up to 78%, 50%, 93% and 50%, respectively.

• The Journal of Korean Society for School & Community Health Education
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• v.1 no.2
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• pp.49-71
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• 2000

The purpose of this study was to serve as a basis for school health care of better quality, by making a comparative analysis of the health care satisfaction and attitude of elementary school students in consideration of their general characteristics and the presence or absence of nurse teacher. The subjects in this study were 919 selected six graders in 16 elementary schools in the city of Tongduchun, Koyang and Euijungbu, Yangju-kun and Yeunchun-kun. A survey was conducted with questionnaire designed for measurement of health care satisfaction and attitude. As a result of analyzing the data collected from June 1 through 15, 2000, the conclusions were as follows. 1) As for the general characteristics of the students investigated, the subjects included 513 boys(55.8%) and 406 girls(44.2%). The schools where 390(42.4%) students attended were located in municipal area, and the schools where 529(57.6%) students attended were located in kun area. 608(66.2%) students had a nurse teacher at their schools, while 311(33.8%) students had no nurse teacher. 498(54.2%) had an experience to use the health room this year, but 421(45.8%) had no such an experience. Their mean school life satisfaction was scored $3.42{\pm}.71$, above the average. And their health condition was rated $3.81{\pm}.87$, which implied they tended to be in good health. 2) The mean satisfaction at the health room operation was scored $3.33{\pm}.71$, above the medium level. What they were most satisfied with($4.02{\pm}1.08$) was, among the health room facilities, that there were beds. But they expressed the least satisfaction($2.83{\pm}1.17$) at the location of health room. The presence or absence of nurse teacher made a significant difference to their satisfactionat health room operation, because the students in schools with nurse teacher showed greater satisfaction($3.42{\pm}.72$) than the others in schools with no nurse teacher did($3.15{\pm}.66$). 3) Concerning their attitude to use the health room in case of disease or accident occurrence, a lot of students in schools with a nurse teacher, who had ever suffered from indigestion, headache or traumatic injury, used the health room. In schools with no nurse teacher, there was a tendency to talk to their class teachers(p<.001). The recognition of the necessity for health counseling was generally on a medium level. The counselor whom they wanted to discuss health problem with was family or friend in the largest cases. Few students discussed with class teachers in case there was a nurse teacher in school. Instead, some of them discussed with friend, family or nurse teacher, and there was a significant difference between them(p<.001). 4) The mean satisfaction at health, sanitation and environmental management was rated $3.20{\pm}.90$, above the average. The classroom lighting gave them the best satisfaction with $3.67{\pm}1.07$, but the satisfaction at toilet cleanness and disinfection was not good with $2.83{\pm}1.19$. By the presence or absence of nurse teacher, those who had a nurse teacher expressed better satisfaction at water supply facilities including hot water than the others who had no nurse teacher did(p<.001). But no significant difference was observed in the other items. 5) The health education satisfaction was rated $3.19{\pm}.99$, which was on a medium level. By item, the mean satisfaction level was $3.36{\pm}1.19$ at nurse teacher's explanation about treatment, $3.13{\pm}1.15$ at the frequency of health education, and $3.08{\pm}1.16$ at the explanation on the cause of disease. By the presence or absence of nurse teacher, the students with nurse teacher showed significantly better satisfaction at every factor0(p<.001). 6) Regarding health education attitude, their recognition of the need for school health education was scored $3.89{\pm}.96$. Those who had a nurse teacher felt it more necessary($3.96{\pm}.92$), yet the others who had no nurse teacher felt its necessity a little less($3.74{\pm}1.01$). The most preferred thing for them to learn in health education was first aid, followed by sex education, obesity prevention, safety accident prevention in school and outdoors, smoking-related health, good use of leisure time, and environmental pollution cause in the order named. According to the presence or absence of nurse teacher, there was a significant difference in sex education(p<.01), but no significant disparities were found in the other factors. The most preferred person who would offer health education was a lecturer from the outside(45.8%) and nurse teacher(45.4%). Their preference for class teacher as a person in charge of health education was just 8.8%. But the presence or absence of nurse teacher didn't produce any differences to their preference for a person in charge of health education.

• Korean Journal of Environmental Agriculture
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• v.26 no.3
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• pp.233-238
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• 2007

To assess pollutant loads in Nakdong river from highland agriculture in Kyungbuk province we. analyzed water qualities such as BOD, COD, T-N, T-P and SS in year 2005. BOD values in rainy period (June and July) were relatively higher than those in dry period, and those in 4 sites among 17 sites ranged from 10.71-19.25 mg/L which exceeded water criteria (8 mg/L) for agricultural use. COD values showed similar trends like BOD values. These trends might be caused by outflow of nutrients applied in agricultural lands. T-N content ranged from 0.1 to 14 mg/L. Those in lower reaches of stream were greater in those in upper stream. Compared to T-N contents during non-farming season, T-N content in farming season were higher. These phenomenon could be due to continuous input of nutrients from small watercourses. Averaged T-P content in lower stream during farming season was 0.4 mg/L, which was eight times higher than the limiting level for algae occurrence (0.05 mg/L). BOD, T-P, T-N loads from alpine agricultural practices were 12.25 $kg/km^2{\cdot}day$, 0.55 $kg/km^2{\cdot}day$ and 32.35 $kg/km^2{\cdot}day$, respectively. These values were greater than those from forestry. Therefore, Best management Practices (BMP) for alpine agricultural field are needed to reduce pollutant loads in Nakdong river.

• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.2
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• pp.1-19
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• 2023

In Korea, excessive vegetation in rivers made up of sand and gravel is emerging as a nationwide problem, which is attributed to increased spring precipitation and decreased annual precipitation. Therefore, this study was conducted for the purpose of identifying the effect of changes in precipitation patterns on river vegetation in Namcheon, Gyeongju, and analyzing the area of vegetation and ecological characteristics. As a result of the study, the amount of monthly precipitation in the summer of Namcheon decreased after 2007, and the area of vegetation increased continuously compared to the area of the sandbank. The proportion of naturalized plants increased steadily when precipitation continued to a level that did not cause flooding, but the area occupied by naturalized plants was small. Also, when the water level is maintained, the species diversity is low due to the dominance of a single species, and the dominant species was mainly native plants. Dominance of native plants inhibited the growth of naturalized plants, but the vegetation area increased even more. Therefore, it is necessary to manage the spread of vegetation itself rather than the division of native plants and naturalized plants in order to eliminate the active growth and prosperity of river vegetation. High water levels and continuous flooding caused by torrential rains in summer disturbed the plant communities, and vegetation formed afterwards was mainly native plants. Such flooding in river ecosystems is a positive factor for the emergence of native plants and over-formed vegetation communities, so it should be considered when establishing a vegetation management plan.

• Korean Journal of Environmental Biology
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• v.40 no.4
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• pp.363-373
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• 2022

On April 29, 2021 (1st), June 2 (2nd), and August 17 (3rd), we surveyed benthic macroinvertebrates fauna at Muljangori-oreum wetland in Bonggae-dong, Jeju Island, Korea. Muljangori-oreum wetland was divided into four areas. The survey was conducted in three accessible areas (areas 1-3). As a result of habitat environment analysis, the average monthly temperature from 2017 to 2021 was the highest in July and August and the lowest in December and February. This pattern was repeated. As a result of analyzing changes in vegetation and water surface area through satellite images, normalized difference vegetation index (NDVI) increased from February to July and decreased after July. Normalized difference water index (NDWI) was analyzed to show an inverse relationship. A total of 21 species from 13 families were identified in the qualitative survey and a total of 412 individuals of 24 species from 15 families were identified in the quantitative survey. A total of 26 species from 17 families, 8 orders, 3 classes, and 2 phyla of benthic macroinvertebrates were identified. The dominant species was Chronomidae spp. with 132 individuals (32.04%). Noterus japonicus was a subdominant species with 71 individuals (17.23%). As a result of comparative analysis of species identified in this study and the literature, it was confirmed that species diversity was high for Coleoptera and Odonata. Main functional feeding groups (FFGs) were found to be predators. Habitat orientation groups (HOGs) were found to be swimmers. In OHC (Odonata, Hemiptera, and Coleoptera) group, 17 species (73.91%) in 2021, 23 species (79.31%) in 2016, 26 species (86.67%) in 2018, and 19 species (79.17%) in 2019 were identified. Cybister japonicus, an endangered species II, was confirmed to inhabit Muljangori-oreum wetland in the literature. Ten individuals (2.43%) were also confirmed to inhabit Muljangori-oreum wetland in 2021. Therefore, continuous management and habitat protection are required to maintain the habitat environment of C. japonicus in Muljangori-oreum wetland.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.3
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• pp.273-283
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• 2020

Because of climate change, the occurrence of localized and heavy rainfall is increasing. It is important to predict floods in urban areas that have suffered inundation in the past. For flood prediction, not only numerical analysis models but also machine learning-based models can be applied. The LSTM (Long Short-Term Memory) neural network used in this study is appropriate for sequence data, but it demands a lot of data. However, rainfall that causes flooding does not appear every year in a single urban basin, meaning it is difficult to collect enough data for deep learning. Therefore, in addition to the rainfall observed in the study area, the observed rainfall in another urban basin was applied in the predictive model. The LSTM neural network was used for predicting the total overflow, and the result of the SWMM (Storm Water Management Model) was applied as target data. The prediction of the inundation map was performed by using logistic regression; the independent variable was the total overflow and the dependent variable was the presence or absence of flooding in each grid. The dependent variable of logistic regression was collected through the simulation results of a two-dimensional flood model. The input data of the two-dimensional flood model were the overflow at each manhole calculated by the SWMM. According to the LSTM neural network parameters, the prediction results of total overflow were compared. Four predictive models were used in this study depending on the parameter of the LSTM. The average RMSE (Root Mean Square Error) for verification and testing was 1.4279 ㎥/s, 1.0079 ㎥/s for the four LSTM models. The minimum RMSE of the verification and testing was calculated as 1.1655 ㎥/s and 0.8797 ㎥/s. It was confirmed that the total overflow can be predicted similarly to the SWMM simulation results. The prediction of inundation extent was performed by linking the logistic regression with the results of the LSTM neural network, and the maximum area fitness was 97.33 % when more than 0.5 m depth was considered. The methodology presented in this study would be helpful in improving urban flood response based on deep learning methodology.

• Journal of Aquaculture
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• v.21 no.2
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• pp.111-122
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• 2008

This study was conducted to assess the usefulness of the temperature characteristics of the tidal flat sediments during low tide as a environmental factor, and burrowing behaviour, fatness, total hemocyte counts(THCs) and differential hemocyte counts(DHCs) of hard clam Meretrix lusoria as biological activity indices for the management of hard clam farms located in Taean(Chungnam province) and Gimje(Jeonbuk province) tidal flat in Korea. Temperature ranges of the sediment at 1cm depth during spring(March to May) and summer(June to August) in Taean(where the exposure time was about $5.5{\sim}6$ hours during low tide) were $8.7{\sim}26.8^{\circ}C\;and\;27.6{\sim}32.8^{\circ}C$, respectively. Even though there was no significant difference(P>0.05), temperatures of the surface sediment where submerged with remained seawater were generally higher than that of uncovered with seawater. Burrowing depths of normally digged hard clams were 0.9{\sim}3.6cm from March to October, 2002. In the field experiment performed at Taean farming ground covered with seawater, burrowing times of the clams under natural water temperatures were $41.6{\pm}10minutes$ in February and $5.4{\pm}1.3minutes$ in August, respectively, and these were influenced by water temperatures. Fatness of hard clams began to decrease from May(at Taean tidal flat) and June(at Gimje tidal flat), showed the lowest level in August and increased again from September. Total hemocytes counts in the hemolymph of the hard clams were decreased to the lowest level in July($24.7{\times}10^4cells/mL$, at Taean tidal flat) and August($28.2{\times}10^4cells/mL$, at Gimje tidal flat), and significantly increased again from September(at Taean tidal flat, P<0.01) and October(at Gimje tidal flat, P<0.001), respectively. We observed three types of hemocytes from the hemolymph of hard clams according to whether hemocytes retain the granules or not and the size of the granules. As a results, we could found that periodical monitoring of the sediment temperatures, clam burrowing behaviour and hemocyte parameters were very helpful for the management of hard clam farming.