• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.784-795
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• 2006

The purpose of this study was to assess biological river water quality by using epilithic diatoms at 40 selected sites in Geum, Youngsan, and Seomjin River systems. The sampling and analyses were performed during three seasons including January, April and June in 2005. Various water quality parameters also were analyzed. We attempted to classify the water quality condition by epilithic diatom indices (DAIpo and TDI) with the results of corresponding analyses of various chemical water quality parameters. A five class system was delivered to describe the water quality condition ranged from "very good" to "very poor." We also proposed a way of classifying water quality condition by combining two diatom indices of DAIpo and TDI. Our results showed that biomass of epilithic diatoms varied not only seasonally but spatially; it was not likely that winter diatoms represent average water quality condition, due to high concentration of nutrients. Water quality status assessed by diatom indices was generally worse than that assessed by BOD, indicating that BOD standard likely underestimates the biological condition of the water body. Importantly, nutrient-based diatom index (TDI) generally overestimated organic matter-based index (DAIpo) at most study sites, indicating that diatoms in studied rivers were likely more affected by nutrients than organic matter. Thus, management strategy to improve river water quality in Korea is suggested to emphasize more on the nutrients than organic matters.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.6
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• pp.119-130
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• 2011

Land-use changes have made considerable impacts on humans and nature such as biodiversity and ecosystem services. It is recognized as important elements for land use planning and regional natural resources conservation to identify the major causes of land use changes and to predict a process of changes and effects. This study, by using a spatially explicit Dyna-CLUE model, analyzed correlations between driving factors, quantified location characteristics of different land use types using logistic regression analysis and examined future land use changes and its effects in Yangpyeong and Yeoju region. We expected land use changes based on the three scenarios with different future land demands and simulated future changes for spatial variations of land use for the 20 years. The outcomes shows that larger change was found in agricultural areas than forest areas, based on the change in built-up areas. The changes in forest areas, which were mainly occurred in edge area, were expected to affect a large impact on its ecotone. It was found to be the importance of the management of forest edge and the necessity of the environmentally sound and sustainable development in order to conserve natural resources of the region.

• Journal of Korea Water Resources Association
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• v.46 no.8
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• pp.795-805
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• 2013

Drought is one of the severe natural disasters and it can profoundly affect our society and ecosystem. Also, it is a very important variable for water resources planning and management. Therefore, the drought is analyzed in this study to understand the drought distribution and trend. The Standard Precipitation Index (SPI) is estimated using precipitation data obtained from 55 rain gauge stations in South Korea and the SPI based drought variables such as drought duration and drought severity were defined. Drought occurrence and joint probabilistic analysis for SPI based drought variables were performed with run theory and copula functions. And then the return period and spatial distribution of droughts on the South Korea was estimated. As the results, we have shown that Gongju and Chungju in Chungcheong-do and Wonju, Inje, Jeongseon, Taebeak in Gangwon-do have vulnerability to droughts.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.7
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• pp.1873-1893
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• 2023

The development of lightweight, low energy and small-sized sensors incorporated with the wireless networks has brought about a phenomenal growth of Wireless Sensor Networks (WSNs) in its different fields of applications. Moreover, the routing of data is crucial in a wide number of critical applications that includes ecosystem monitoring, military and disaster management. However, the time-delay, energy imbalance and minimized network lifetime are considered as the key problems faced during the process of data transmission. Furthermore, only when the functionality of cluster head selection is available in WSNs, it is possible to improve energy and network lifetime. Besides that, the task of cluster head selection is regarded as an NP-hard optimization problem that can be effectively modelled using hybrid metaheuristic approaches. Due to this reason, an Improved Coyote Optimization Algorithm-based Clustering Technique (ICOACT) is proposed for extending the lifetime for making efficient choices for cluster heads while maintaining a consistent balance between exploitation and exploration. The issue of premature convergence and its tendency of being trapped into the local optima in the Improved Coyote Optimization Algorithm (ICOA) through the selection of center solution is used for replacing the best solution in the search space during the clustering functionality. The simulation results of the proposed ICOACT confirmed its efficiency by increasing the number of alive nodes, the total number of clusters formed with the least amount of end-to-end delay and mean packet loss rate.

• Journal of Wetlands Research
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• v.21 no.1
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• pp.9-15
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• 2019

The Daegi-cheon watershed is located in the upper part of the Han River, which has the representative highland vegetable growing complexes. This watershed has a large impact on the water quality and aquatic ecosystem in the upstream of the Han River by discharging a large amount of turbid water during rainfall season. For proposing an efficient turbid water management and policy, the analysis of the characteristics of flow rate and SS and its causes needs to be carried out preferentially. In this study, the relationship between flow rate and SS concentration was analyzed in the Daegi-cheon watershed, and in turn the turbidity characteristics were analyzed. As a result of the study, in the normal flood flow condition, it was shown that SS concentration changed arbitrarily due to various environmental factors. On the other hand, the SS concentration was considerably high in the very high flow condition. Based on the field survey, this could be the reason why the effects of the steep valley and slope collapse according to the very high flow rate as well as the source in the agricultural fields were greatly contributed. Therefore, it is necessary to develop a structural best management practice that can stabilize the steep slope and reduce river bed loss along with the typical source managements plans.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.488-496
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• 2018

This study examined the Gangwon Province's current implementation of its elimination of invasive plants and explored a plan to effectively manage invasive plants. The percentage of the distribution of the plants was 39.6% for riverside areas, 23.3% for roadside areas, 12.4% for roadside & riverside areas, and 4.6% for areas around farm land and river banks. To ensure the systematic management of invasive plants, the current study suggests a) developing an invasive plants monitoring and management system; b) reinvigorating the participation of residents, private organizations, and military posts; c) planting of native replacement plants and the conversion of the locations as attractions, and d) nurturing the project for using invasive plants. For policy directions to be pursued based on the results of the study, the following are suggested: a) improving laws and systems regarding invasive plants, b) developing a cooperative system for managing invasive plants, c) implementing the training of civilian professionals, d) implementing the elimination of invasive plants, e) developing replacement plants for cities and counties, f) fostering industries that tap into invasive plants, and g) using the Han River Water System Management Fund for funding and greater efficiency.

• Korean Journal of Environmental Biology
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• v.33 no.1
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• pp.1-6
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• 2015

Increased harmful algal blooms by cyanobacteria are threatening public health and limiting human activities related with freshwater ecosystems. Phosphorus (P) has long been suggested as a critical nutrient for cyanobacterial bloom through field research in Canada during the 1970s, proposing a P-based freshwater management guideline. However, recently, nitrogen (N) has also been highlighted as an impacting nutrient on cyanobacterial harmful algal blooms (CyanoHABs). Due to the intensive and frequent observation of Microcystis, this kind of paradigm shift from P limitation to season-dependent N or P limitation has an important implication for a dual nutrient management strategy in eutrophic freshwaters. Through recent international researches, general strategies to control CyanoHABs in lakes and reservoirs are as follows: a dual nutrient (N & P) reduction, wastewater collection and treatment, pre-treatment of influent water in buffer zones, dredging of sediment, reduction of residence time, algal collection, and precipitation and flocculation of cyanobacteria. In addition, sustainable and integrative freshwater algae management should be carried out, based on the ecological aspect, because cyanobacteria are not the target organism to be eradicated, but an essential microbial member in the freshwater ecosystem.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.267-273
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• 2023

Algae are an important component of the ecosystem. However, the excessive growth of cyanobacteria has various harmful effects on river environments, and diatoms affect the management of water supply processes. Algal monitoring is essential for sustainable and efficient algae management. In this study, an object detection model was developed that detects and classifies images of four types of harmful cyanobacteria used for the criteria of the algae alert system, and one diatom, Synedra sp.. You Only Look Once(YOLO) v8, the latest version of the YOLO model, was used for the development of the model. The mean average precision (mAP) of the base model was analyzed as 64.4. Five models were created to increase the diversity of the input images used for model training by performing rotation, magnification, and reduction of original images. Changes in model performance were compared according to the composition of the input images. As a result of the analysis, the model that applied rotation, magnification, and reduction showed the best performance with mAP 86.5. The mAP of the model that only used image rotation, combined rotation and magnification, and combined image rotation and reduction were analyzed as 85.3, 82.3, and 83.8, respectively.

• Journal of Korean Society of Forest Science
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• v.80 no.4
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• pp.369-378
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• 1991

Major statutory nature protection areas include Nature Parks, Nature Reserves. Nature Ecological System Protected Areas. Biosphere Reserves, Nature Protected Forests, Wildlife Sanctuaries, and Protection Forests with total area of 1,124,000 ha. These protected areas cover almost 18% of the forested area. The number of visitors of NPs reached over 33 million per year with sharp increasing rate over the years. To protect the deteriorated hiking trails and camp grounds caused by overuse, two management policies have been implemented : cooking prohibition and natural rest rotation system. While prohibition of cooking is based on the fact that most of the solid wastes in nature parks are leftovers of cooking, natural rest rotation system is mainly for rehabilitation of deteriorated areas by natural processes. The system has closed 47 trails(in 27 mountains) throughout the country since January 1991, which is scheduled to continue 3 years. Due to the lack of accumulated scientific knowledge on how, when and where to close, application of the system leaves much to be desired. This paper discusses the current efforts to protect the natural resources for recreational use and suggests future directions for an effective policy implementation.

• Korean Journal of Ecology and Environment
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• v.36 no.1 s.102
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• pp.48-56
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• 2003

This study was evaluated about the seasonal variations of ecosystem in Nammae Reservoir based on the interrelation of physico-chemical characteristics, nutrients, chlorophyll a, b, c and standing crops of phytoplanktons. The amounts of chlorophyll a, b, c were respectively maximum (295 mg/, 9.5mg/l and 48mg/l) at station 1 in June and the standing crop of phytoplanktons was the highest ($1.7{\time}10^5$ cells/1) at stations 3 in July. The range of temperature was $7{\sim}37.4^{\circ}C$. The maxium of pH was $9.9{\sim}10.1$ at all stations in August, the minimum was 7 in September. SS was maximum (308 mg/1) at station 1 in June, while it was minimum (4 mg/l) at the same station in November. The maximal COD and DOC were 33 mg/1 and 16 mg/1 respectively at station 1 in June. As for phytoplanktons, Microcystis aeruginosa, blue-green alga in July${\sim}$August, Scenedesmus acutus, green alga in March${\sim}$May and November${\sim}$January and Cyclotella orientalis, Diatoms in October were dominant species. The amounts of P and Si were generally high in summer, they were low in autumn and winter. Nammae Reservoir assessed by trophic state index was eutrophicated and overtrophicated. These results indicated that Nammae Reservoir was faced with heavy water pollution. As preceding management for the basin of the Reservoir, it will have to be continually studied for an ecosystem reservation.