• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.145-156
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• 2006

The objective of this study was to evaluate biological health conditions and physicochemical status using multi-metric models at five sites of the Keum-Ho River during August 2004 and June 2005. The research approach was based on a qualitative habitat evaluation index (QHEI), index of biological integrity (IBI) using fish assemblage, and long-term chemical data (1995 ${\sim}$ 2004), which was obtained from the Ministry of Environment, Korea. For the biological health assessments, regional model of the IBI in Korea (An,2003), was applied for this study. Mean IBI in the river was 30 and varied from 23 to 48 depending on the sampling sites. The river health was judged to be "fair condition", according to the stream health criteria of US EPA (1993) and Barbour et al. (1999). According to the analysis of the chemical water quality data of the river, BOD, COD, conductivity, TP, TN, and TSS largely varied epending on the sampling sites, seasons and years. Variabilities of some parameters including BOD, COD, TP, TN, and conductivity were greater in the downstream than in the upstream reach. This phenomenon was evident in the dilution by the rain during the monsoon. This indicates that precipitation is a very important factor of the chemical variations of water quality. Community analyses showed that species diversity index was highest (H=0.78) in the site 1, while community dominance index was highest in the site 3, where Opsariichthys uncirostris largely dominated. In contrast, the proportions of omnivore and tolerant species were greater in the downstream reach, than in the upstream reach. Overall, this study suggests that some sites in the downstream reach may need to restore the aquatic ecosystem for better biological health.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.3
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• pp.10-20
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• 2019

Irregular rainfall caused by climate change, in combination with non-point pollution, can cause water systems worldwide to suffer from frequent eutrophication and algal blooms. This type of water pollution is more common in agricultural prone to water system inflow of non-point pollution. Therefore, in this study, the correlation between Unmanned Aerial Vehicle(UAV) multi-spectral images and total phosphorus, total nitrogen, and chlorophyll-a with indirect association of algal blooms, was analyzed to identify the usability of UAV image to identify water quality characteristics in agricultural streams. The analysis the vegetation index Normalized Differences Index (NDVI), the Normalized Differences Red Edge(NDRE), and the Chlorophyll Index Red Edge(CIRE) for the detection of multi-spectral images and algal blooms collected from the target regions Yang cheon and Hamyang Wicheon. The analysis of the correlation between image values and water quality analysis values for the water sampling points, total phosphorus at a significance level of 0.05 was correlated with the CIRE(0.66), and chlorophyll-a showed correlation with Blue(-0.67), Green(-0.66), NDVI(0.75), NDRE (0.67), CIRE(0.74). Total nitrogen was correlated with the Red(-0.64), Red edge (-0.64) and Near-Infrared Ray(NIR)(-0.72) wavelength at the significance level of 0.05. The results of this study confirmed a significant correlations between multi-spectral images collected through UAV and the factors responsible for water pollution, In the case of the vegetation index used for the detection of algal bloom, the possibility of identification of not only chlorophyll-a but also total phosphorus was confirmed. This data will be used as a meaningful data for counterplan such as selecting non-point pollution apprehensive area in agricultural area.

• Ecology and Resilient Infrastructure
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• v.8 no.2
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• pp.79-87
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• 2021

Because active interactions occur among vegetation, hydrology, and geomorphology in riparian systems, any changes in one of these factors can significantly affect the other two. In this study, we evaluated these interactions at four sites (two in Gajeong and two in Hahan) along the Seomjin-gang River that was substantially devastated by an extreme flood in 2020. We examined the relationship between the riparian vegetation and the hydraulic characteristics of the flood using remote sensing, hydraulic modeling, and field surveys combined. The evaluation results showed that the floods caused a record-breaking rise of up to 43.1 m above sea level at the Yeseong-bridge stage gauge station (zero elevation 27.4 m) located between the Gajeong and Hahan sites, with the shear stress being four times higher in Hahan than in Gajeong. Additionally, the water level during the flood was estimated to be a maximum of 1 m higher depending on the location in the presence of riparian plants. Furthermore, both sites underwent extensive biological damage due to the flood, with 78-80% loss in vegetation, with preferential damage observed in large willow species, compared to Quercus acutissima. The above findings imply that all plant species exhibit different vulnerabilities towards extreme floods and do not induce similar behavior towards events causing a disturbance. In conclusion, we developed strategies for effectively managing riparian trees by minimizing flood hazards that could inevitably cause damage.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.2
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• pp.121-127
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• 1985

This study was designed to gain practical data on the use of soil conditioners for more efficient water managements and to establish the optimum levels of structural properties for soil conditioning. A sandy loam and a silt loam soil were each treated with two different soil conditioners, hydrophobic Bitumen or hydrophilic Uresol. The perspex tube 34 cm long were packed homogeneously with air dried soil up to 2 cm below the top, then covered over 2 cm of treated or untreated aggregates. The infiltration rate into the soil columns was measured under simulated rainfall condition. The evaporation study was carried out in the wind tunnel, and the changes of soil moisture distribution of the columns following and during the evaporation were determined by a gamma ray scanner. The infiltration rate of water into the soil column was increased to 18.7-50.8% by the Uresol treatment but it was decreased to less than 25% of control by the Bitumen treatment. Evaporation was decreased to 22.0-68.1% by the Bitumen treatment and to 38.7-68.4% by the Uresol treatment. The water use efficiency of Uresol treated column was increased to more than twice as much as that of untreated soil. Aggregate stability and wetting angle were related to water infiltration and evaporation. A positive and highly significant logarismic relationship was found between the infiltration rate and stability index-wetting angle, evaporation rate and instability index-wetting angle. It was considered that the structural stability is more important than wetting angle. This is true because the structural stability is always positively correlated to water saving, however wettability is positively correlated to the infiltration, and negatively correlated to water saving during the evaporation.

• The Korean Journal of Pesticide Science
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• v.10 no.2
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• pp.99-106
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• 2006

Chlorothalonil and imidacloprid sprayed onto the green peppers were degraded more faster at outdoor than in greenhouse. These results were affected by dew and photodegration, considering no rain during the experimental period. Chlorothalonil, esfenvalerate and imidacloprid in green pepper, green twist pepper and sweet pepper did not show any residual pattern, because green peppers are one of the continuous harvesting crops and pesticides could not be sprayed homogeneously on them. When green peppers were pickled with soy sauce and green twist peppers were fried with vegetable oil, the amounts of pesticides such as alpha-cypermethrin, bifenthrin, chlorfenapyr, esfenvalerate and imidacloprid were diminished to the levels of about $30{\sim}71$ and $20{\sim}41%$, respectively. Esfenvalerate and imidacloprid could not be detected in 2 month-old hot pepper paste. The removal rates of pesticide residues in leaves of green peppers were about $22{\sim}37%$ by washing, about $74{\sim}95%$ by parboiling, and about $17{\sim}55%$ by drying after parboiling.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.6
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• pp.658-665
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• 2013

In this study, we measured particulate matter(PM) which emerged as the hot issue from the International Maritime Organization(IMO) and the exhaust emission using HANBADA, the training ship of Korea Maritime University. In particular, the PM was obtained with TEM grid. PM structure was observed by electron microscopy. And exhaust gases such as NOx, $CO_2$, and CO were measured using the combustion gas analyzer(PG-250A, HORIBA). The results of this study are as follows. 1) When the ship departed from the port, the maximum difference in PM emissions were up to 30 % due to the Bunker Change. 2) Under the steady navigation, emission of PM was $1.34mg/m^3$ when Bunker-A is changing L.R.F.O(3 %). And, at the fixed L.R.F.O (3 %), emission of PM was $1.19mg/m^3$. When the main engine RPM increased up to 20 % with fixed L.R.F.O(3 %), emission of PM was $1.40mg/m^3$. When we changed to low quality oil(L.R.F.O(3 %)), CO concentration from main engine increased about 16 %. On the other hand, when the main engine RPM is rising up to 20 %, CO concentration is increased more than 152 percent. These results imply that the changes of RPM is a dominant factor in exhaust emission although fuel oil type is an important factor. 3) The diameter of PM obtained with TEM grid is about $4{\sim}10{\mu}m$ and its structure shows porous aggregate.

• Journal of Korean Society of Forest Science
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• v.76 no.3
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• pp.230-240
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• 1987

Half-sib seedlings of Ginkgo biloba (one-year-old) were treated with various simulated acid rains(pH2.0, pH3.0, pH4.0 and pH5.0) to examine the effects of acid rain on leaf surface area, leaf injury, leaf chlorophyll content and photosynthetic ability of the leaf tissue. The seedlings were grown in a pot($4500cm^3$) containing one of three different soils(nurseryy soil, mixed soil and sandy soil). Simulated acid rain was made by diluting sulfuric and nitric acid solution($H_2SO_4:HNO_3=3:1$, V/V) with tap water and tap water(pH6.4), and treated by 5mm each time for three minutes during the growing seasons(April to October 1985). Acid rain treatments were done three times per week to potted seedlings by spraying the solutions. The results obtained in this study were as follows : 1. Leaf surface area per seedling at pH2.0 level was the lowest among the levels of pH, but those at other pH levels were not significantly different. 2. Leaf injury(injured leaf rate and injured leaf area) increased with decreasing pH levels of acid rain. 3. Leaf chlorophyll content measured during the period June through October was significantly different among the soil types, and that of the seedling in nursery soil was the highest. The lower pH levels of simulated acid rain was treated ; more leaf chlorophyll content was measured at the beginning of treatment, and the more it severely decreased at the late growing period. 4. Photosyntetic abilities, and the highest value was shown in nursery soil. Significand difference in photosynthetic ability among the levels of pH was observed only in August. Photosynthetic ability increased with decreasing pH levels at the beginning of treatment, but decreased rapidly after July.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.1
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• pp.25-34
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• 2015

In this research, we applied a procedure of quality control (QC) to the agro-meteorological data measured at the Suwon weather station of Korea Meteorological Administration (KMA). The QC was conducted through six steps based on the KMA Real-time Quality control system for Meteorological Observation Data (RQMOD) and four steps based on the International Soil Moisture Network (ISMN) QC modules. In addition, we set up our own empirical method to remove erroneous data which could not be filtered by the RQMOD and ISMN methods. After all these QC procedures, a well-refined agro-meteorological dataset was complied at both air and soil temperatures. Our research suggests that soil moisture requires more detailed and reliable grounds to remove doubtful data, especially in winter with its abnormal variations. The raw data and the data after QC are now available at the NCAM website (http://ncam.kr/page/req/agri_weather.php).

• Journal of Korea Water Resources Association
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• v.56 no.4
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• pp.261-272
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• 2023

In recent years, natural disasters such as heavy rainfall and typhoons have occurred more frequently, and their severity has increased due to climate change. The Korea Meteorological Administration (KMA) currently uses the same criteria for all regions in Korea for watch and warning based on the maximum cumulative rainfall with durations of 3-hour and 12-hour to reduce damage. However, KMA's criteria do not consider the regional characteristics of damages caused by heavy rainfall and typhoon events. In this regard, it is necessary to develop new criteria considering regional characteristics of damage and cumulative rainfalls in durations, establishing four stages: blue, yellow, orange, and red. A classification model, called DSCM (Disaster Severity Classification Model), for the four-stage disaster severity was developed using four machine learning models (Decision Tree, Support Vector Machine, Random Forest, and XGBoost). This study applied DSCM to local governments of Seoul, Incheon, and Gyeonggi Province province. To develop DSCM, we used data on rainfall, cumulative rainfall, maximum rainfalls for durations of 3-hour and 12-hour, and antecedent rainfall as independent variables, and a 4-class damage scale for heavy rain damage and typhoon damage for each local government as dependent variables. As a result, the Decision Tree model had the highest accuracy with an F1-Score of 0.56. We believe that this developed DSCM can help identify disaster risk at each stage and contribute to reducing damage through efficient disaster management for local governments based on specific events.

• Journal of The Korean Society of Grassland and Forage Science
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• v.33 no.2
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• pp.123-130
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• 2013

This study was conducted to investigate the effects of climate change on the growth characteristics and dry matter yields of silage corn hybrids in fields of forage crops of Hanwoo Experiment Station, National Institute of Animal Science, RDA, from Apr. 2009 to Sep. 2011. Corn hybrids were cultivated in Daegwallyeong of Gangwon Province, at an altitude of 760 m. Corn varieties used in this study consisted of 5 domestic varieties and 5 foreign varieties. Differences of silk days according to years occurred at an average of 5.5 days. The silk periods of domestic varieties occurred from Aug. 8 to 12, while that of overseas varieties was from Aug. 5 to 11. Silk days of domestic varieties occurred approximately 3 to 4 days earlier than those of oversea varieties. Silk days of Kwangpyeongok and P3156 belonging to the early varieties were Aug. 8 and 5, respectively. Kwangpyeongok and P3156 were Aug. 8 and 5, respectively. Pyeonganok and DK729 belonged to late varieties. The mean plant height of corn was approximately 231 cm, while those of Kwangpyeongok and Pyeonganok were 236 cm and 237 cm, respectively. The mean stem diameter and ear height of corn were approximately 23.2 mm and 94 cm, respectively. In the case of stem diameters, those of Cheonganok and 33J56 were 86 cm and 80 cm, respectively, while Gangdaok grew to a greater height (enter height) than other varieties. Dry matter yields of Kwangpyeongok and Pyeonganok were higher than those of other varieties. The mean leaf ratio of corn was 39.3%, while that of domestic varieties increased as compared to foreign varieties. The average DM yield of corn was 16,653 kg/ha, while those of 32P75, P3156, Pyeonganok, P3394 and Kwangpyeongok were 18,901, 17,997, 17,675, 17,194, 17,188 kg/ha, respectively. Total digestible nutrient (TDN) yields of 32P75, P3156, P3394, Pyeonganok and Kwangpyeongok were 13,381, 12,590, 12,532, 12,140 and 12,036 kg/ha, respectively. Corn crude protein (CP), in vitro dry matter digestibility (IVDMD), neutral detergent fiber (NDF), acid detergent fiber (ADF) and TDN were 7.8%, 74.2%, 42.4%, 23.5% and 70.3%, respectively. In the case of nutritive values of corn, there was no significant difference between of corn varieties of domestic and foreign origin.