• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.708-720
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• 2021

As hypoxia adversely affects the marine environment in northwestern Gamak Bay every summer, the present study determined its comprehensive occurrence mechanisms using the Multiple Regression Analysis (MRA) and suggested management directions based on the primary MRA factors. The first hypoxia occurred by thermocline related to weather conditions, with organic matter deposited inside the bay on 26^th June, 2017. Additionally, on 12^th July, halocline was also developed by increased rainfall, and the hypoxia was most expanded horizontally and vertically. The primary factors were the stratification and deposited organic matter. In contrast, the hypoxia correlated to phytoplankton growth and deposited organic matter on 8^th August was diminished with remarkably less precipitation. However, the stable halocline was caused by massive precipitation, and the reproduced phytoplankton re-generated the expanded hypoxia on 16^th August despite a short sampling interval. Subsequently, the hypoxia influenced by the deposited organic matter spread shallowly along the seafloor on 13^th September as the extinction period. These results suggest that stratification alleviation technologies, and the improvement and removal of the organic matter deposited on the surface sediment are necessary.

• Journal of Ginseng Culture
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• v.6
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• pp.51-79
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• 2024

In the 1970s and 1980s, during the nascent phase of ginseng disease research, efforts concentrated on isolating and identifying pathogens. Subsequently, their physiological ecology and pathogenesis characteristics were scrutinized. This led to the establishment of a comprehensive control approach for safeguarding major aerial part diseases like Alternaria blight, anthracnose, and Phytophthora blight, along with underground part diseases such as Rhizoctonia seedling damping-off, Pythium seedling damping-off, and Sclerotinia white rot. In the 1980s, the sunshade was changed from traditional rice straw to polyethylene (PE) net. From 1987 to 1989, focused research aimed at enhancing disease control methods. Notably, the introduction of a four-layer woven P.E. light-shading net minimized rainwater leakage, curbing Alternaria blight occurrence. Since 1990, identification of the bacterial soft stem rot pathogen facilitated the establishment of a flower stem removal method to mitigate outbreaks. Concurrently, efforts were directed towards identifying root rot pathogens causing continuous crop failure, employing soil fumigation and filling methods for sustainable crop land use. In 2000, adapting to rapid climate changes became imperative, prompting modifications and supplements to control methods. New approaches were devised, including a crop protection agent method for Alternaria stem blight triggered by excessive rainfall during sprouting and a control method for gray mold disease. A comprehensive plan to enhance control methods for Rhizoctonia seedling damping-off and Rhizoctonia damping-off was also devised. Over the past 50 years, the initial emphasis was on understanding the causes and control of ginseng diseases, followed by refining established control methods. Drawing on these findings, future ginseng cultivation and disease control methods should be innovatively developed to proactively address evolving factors such as climate fluctuations, diminishing cultivation areas, escalating labor costs, and heightened consumer safety awareness.

• Korean Journal of Environmental Agriculture
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• v.22 no.4
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• pp.241-245
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• 2003

This study was carried out to evaluate the status of the groundwater quality for paddy fields irrigation in Korea. Water samples were collected at 130 sites throughout the country. Samples were collected at three seasons - April, July and October - in 2000. According to our survey, the groundwater was found to be suitable for irrigation purpose. Average EC was shown 0.286 dS/m. Nitrate-nitrogen and $Cl^-$ concentration was 5.6 mg/L, 32.95 mg/L which satisfied the Korean Standards for Irrigation Water. Nitrate-nitrogen concentration in each province was shown as following orders: Jeju (11.17 mg/L) > Chungnam (8.16 mg/L) > Gyeongbuk (6.64 mg/L) > Gyounggi (5.91 mg/L) > Chungnam (4.95 mg/L) > Gyeongnam (3.91 mg/L) > Jeonbuk (3.50 mg/L) > Jeonnam (3.27 mg/L) > Gangwon (2.91 mg/L). The concentration by sampling seasons were October (6.62 mg/L) > July (5.88 mg/L) > April (4.78 mg/L). As the soil of Jeju Province is usually derived from volcanic ash soils mainly used for upland drops, it may influence the nitrate-nitrogen concentration of groundwater. The amount of rainfall also influence the water quality. But the $COD_{Cr}$ were shown April (3.17 mg/L) > July (2.91 mg/L) > October (2.40 mg/L), it is highly related in the basal dose of organic matter fertilizers. This study demonstrated that groundwater quality was suitable for irrigation, but continuous monitoring is recommended for agricultural policy and developing OECD agricultural environment indicators.

• Journal of Korean Society on Water Environment
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• v.33 no.6
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• pp.715-721
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• 2017

Tree box filters, an example of bioretention systems, were compacted and versatile urban stormwater low impact development technique which allowed volume and water quality treatment performance to be adjusted based on the hydrologic, runoff quality and catchment characteristics. In this study, the overall performance of a 6 year-old tree box filter receiving parking lot stormwater runoff was evaluated. Hydrologic and hydraulic factors affecting the treatment performance of the tree box filter were also identified and investigated. Based on the results, the increase in rainfall depth caused a decrease in hydrologic and hydraulic performance of the tree box filter including volume, average flow, and peak flow reduction (r = -0.53 to -0.59; p<0.01). TSS, organics, nutrients, and total and soluble heavy metals constituents were significantly reduced by the system through media filtration, adsorption, infiltration, and evapotranspiration mechanisms employed in the tree box filter (p<0.001). This significant pollutant reduction by the tree box filter was also found to have been caused by hydrologic and hydraulic factors including volume, average flow, peak flow, hydraulic retention time (HRT) and runoff duration. These findings were especially useful in applying similarly designed tree box filter by considering tree box filter surface area to catchment area of less than 1 %.

• Journal of Korea Water Resources Association
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• v.48 no.6
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• pp.463-477
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• 2015

The recent unusual climate and extreme weather events have frequently given unexpected disaster and damages, facing difficulties in the management of water resources. In particular, climate change could result in intensified typhoons, and this would be the worst case scenario that can happen. The primary objective of this study is to identify the patterns of typhoon-induced precipitation and the associated synoptic pattern. This study focused on analyzing precipitation patterns over the South Korea using historic records as opposed to a specified season or duration, and further investigates the potential connection with heavy rainfall to synoptic patterns. In this study, we used the best track data provided by the Regional Specialized Meteorological Center of Japan for 40 years from 1973 to 2012. The patterns of the typhoon-induced precipitation were categorized into four groups according to a given typhoon track information, and then the associated synoptic climatology patterns were further investigated. The results demonstrate that the typhoon-induced precipitation patterns could be grouped and potentially simulated according to the identified synoptic patterns. Our future work will focus on developing a short-term forecasting model of typhoon-induced precipitation considering the identified climate patterns as inputs.

• Journal of Wetlands Research
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• v.17 no.1
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• pp.80-90
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• 2015

Variability of precipitation pattern and intensity are increasing due to the urbanization and industrialization which induce increasing impervious area and the climate change. Therefore, more severe urban inundation and flood damage will be occurred by localized heavy precipitation event in the future. In this study, we analyze the future frequency based precipitation under climate change based on the regional frequency analysis. The observed precipitation data from 58 stations provided by Korea Meteorological Administration(KMA) are collected and the data period is more than 30 years. Then the frequency based precipitation for the observed data by regional frequency analysis are estimated. In order to remove the bias from the simulated precipitation by RCP scenarios, the quantile mapping method and outlier test are used. The regional frequency analysis using L-moment method(Hosking and Wallis, 1997) is performed and the future frequency based precipitation for 80, 100, and 200 years of return period are estimated. As a result, future frequency based precipitation in South Korea will be increased by 25 to 27 percent. Especially the result for Jeju Island shows that the increasing rate will be higher than other areas. Severe heavy precipitation could be more and more frequently occurred in the future due to the climate change and the runoff characteristics will be also changed by urbanization, industrialization, and climate change. Therefore, we need prepare flood prevention measures for our flood safety in the future.

• Korean Journal of Medicinal Crop Science
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• v.15 no.4
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• pp.261-265
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• 2007

A climatic feature, growth condition and incidence phase of disease and pest in Korean ginseng (Panax ginseng C. A. Meyer) were surveyed, both the conventional cultivation and culture in the forest located in Jinan. The results were as follows. The forest field was lower $1^{\circ}C$ in the air temperature, lower $1.9^{\circ}C$ in the soil temperature and 11.8% lower in the soil temperature compared with the conventional field. The wind velocity of the forest field was three times slower, but the dew condensation time was 3.3 hours longer than the conventional field. Particularly, the amounts of solar radiation in the forest was remarkably lower, while the rainfall was little lower with no significance. The incidence of disease and pest in the forest field was severe compared with that of the conventional field. Among them, Colletotrichum gloeosporioides, Cylindrocarpon destructans, and Alternaria panax was severe in the forest field while, Botrytis cinerea was severe in the conventional field. The growth condition of forest field in Panax ginseng C. A. Meyer was 50% worse in general and the root weight was 87.2% less than the 3-year-old ginseng in the conventional field.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.1
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• pp.47-53
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• 2011

From 12 to 16 July 2006, 4 days' torrential rainfall in Deoksan-ri, Inje-up, Inje-gun, Gangwon-do caused massive landslide and debris flow. Huge losses of both life and property, including two people buried to death in submerged houses, resulted from this disaster. As the affected region is mostly mountainous, it was difficult to approach the region and to estimate the exact extent of damage. But using aerial photographs, we can define the region and assess the damage quickly and accurately. In this study the debris flow region in inje, Gangwon-do was analyzed using aerial photographs. This region was divided into three sections - beginning section, flow section and sedimentation section. Informations for each section were extracted by digitizing the shot images with visual reading. Topographic, forest physiognomic and soil characteristics and debris flow occurrences of this region were analyzed by overlaying topographic map, forest type map and soil map using GIS. Comprehensive analysis shows that landslide begins at slope of about $36^{\circ}$, flows down at $26^{\circ}$ slope, and at $21^{\circ}$ slope it stops flowing and deposits. Among forest physiognomic factors, species of trees showd significant relationship with debris flow. And among soil factors, effective soil depth, soil erosion class, and parent materials showed meaningful relationship with debris flow.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.13-20
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• 2006

The changing patterns of water temperature and turbidity in streams entering Imha Reservoir were studied. The turbidity variation near the intake tower in Imha Reservoir was investigated in relation with the variation of water temperature and turbidity in streams. Water temperature was estimated using multi-regression method with air temperature and dew point as independent variables. Peak turbidity was also estimated using non-linear regression method with rainfall intensity as an independent variable. Although more independent variables representing watershed characteristics seem to be needed to increase estimation accuracies, the methodology used in this study can be applied to estimate water temperature and peak turbidity in other streams.

• Journal of Korea Water Resources Association
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• v.53 no.4
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• pp.259-271
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• 2020

In Korea, snow damage has happened in the region with little snowfalls in history. Also, accidental damage was caused by heavy snow leads and the public interest on heavy snow has been increased. Therefore, policy about the Natural Disaster Reduction Comprehensive Plan has been changed to include the mitigation measures of snow damage. However, since heavy snow damage was not frequent, studies on snowfall have not been conducted on different points. The characteristics of snow data commonly are not the same as the rainfall data. Some southern coastal areas in Korea are snowless during the year. Therefore, a joint probability distribution was suggested to analyze the snow data with many 0s in a previous research and fitness from the joint probability distribution was higher than the conventional methods. In this study, snow frequency analysis was implemented using the joint probability distribution and compared to the design codes. The results were compared to the design codes. The results of this study can be used as the basic data to develop a procedure for the snow frequency analysis in the future.