• Journal of Korea Water Resources Association
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• v.31 no.3
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• pp.253-267
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• 1998

In this study, ILLUDAS and SWMM were applied for Dongsucheon basin, Incheon and Test basin, Cheongju. The main parameters (II, IA, IS, SI, SR, SS) which are included in those of each model depending on runoff results were determined, and sensitivity ratios were estimated in order to evaluate and compare the characteristics of each modEL. Total runoff ratio for almost parameters turned out to have a linear relation to the rainfall durations and the scale of basin area but have nothing to do with rainfall distributions. Sensitivity ratios turned out to have a linear relation for the infiltration and soil parameters of ILLUDAS as well as all parameters of SWMM. ronoff sensitivity ratios for almost parameters were smaller than 1.0 because the impacts of total runoff were bigger than those of peak runoff. And runoff sensitivity ratio was equal to 1.0 for the roughness coefficient of SWMM. Total runoff ratio, peak runoff ratio and runoff sensitivity ratio for the selected parameters of those models were presented asthe tables and figures according to the scale of basin area, rainfall durations such as 60, 120, and 180 minutes and Huff's 4th quartiles rainfall distributions. Keywords : ILLUDAS, SWMM, parameter, sensitivity analysis, sensitivity ratio.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.922-928
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• 2011

In order to properly manage the quality of water in Juam Lake, distributions and growth characteristics of submerged plants in Boknae flood control reservoir were investigated. In addition, the total amount of nutrient load by submerged plants were investigated. The total vegetation area was $1,146,849m^2$ of total flood control reservoirs ($1,848,568m^2$) before flooding. By August 19, all of Boknae flood control reservoir was flooded during rainy season. Dominant plants were MISSA (Miscanthus sacchariflorus), SCPMA (Scirpus fluviatilis) and CRXDM (Carex dimorpholepis) which occupied 87% of all flood control reservoirs. The total amounts of organic matter loads at different submerged plants were great in the order of CRXDM ($501,642kg\;area^{-1}$) > SCPMA ($20,987kg\;area^{-1}$) > MISSA ($3,413kg\;area^{-1}$). The total amounts of nitrogen loads by CRXDM, SCPMA and MISSA under different submerged plants were 56%, 3.9% and 0.8%, respectively. The total amounts of phosphorus loads at different submerged plants were on the order of CRXDM ($1,842kg\;area^{-1}$) > SCPMA ($78kg\;area^{-1}$) > MISSA ($14.8kg\;area^{-1}$). Therefore, the results of this study suggest that organic matter, T-N and T-P in water quality of Juam lake were strongly influenced by submerged plants in flood control reservoir.

• Journal of Korea Water Resources Association
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• v.45 no.3
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• pp.301-316
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• 2012

Two models, TANK and SWAT (Soil and Water Assessment Tool) were compared for simulating natural flows in the Paldang Dam upstream areas of the Han River basin in order to understand the limitations of TANK and to review the applicability and capability of SWAT. For comparison, simulation results from the previous research work were used. In the results for the calibrated watersheds (Chungju Dam and Soyanggang Dam), two models provided promising results for forecasting of daily flows with the Nash-Sutcliffe model efficiency of around 0.8. TANK simulated observations during some peak flood seasons better than SWAT, while it showed poor results during dry seasons, especially its simulations did not fall down under a certain value. It can be explained that TANK was calibrated for relatively larger flows than smaller ones. SWAT results showed a relatively good agreement with observed flows except some flood flows, and simulated inflows at the Paldang Dam considering discharges from upper dams coincided with observations with the model efficiency of around 0.9. This accounts for SWAT applicability with higher accuracy in predicting natural flows without dam operation or artificial water uses, and in assessing flow variations before and after dam development. Also, two model results were compared for other watersheds such as Pyeongchang-A, Dalcheon-B, Seomgang-B, Inbuk-A, Hangang-D, and Hongcheon-A to which calibrated TANK parameters were applied. The results were similar to the case of calibrated watersheds, that TANK simulated poor smaller flows except some flood flows and had same problem of keeping on over a certain value in dry seasons. This indicates that TANK application may have fatal uncertainties in estimating low flows used as an important index in water resources planning and management. Therefore, in order to reflect actually complex and complicated physical characteristics of Korean watersheds, and to manage efficiently water resources according to the land use and water use changes with urbanization or climate change in the future, it is necessary to utilize a physically based watershed model like SWAT rather than an existing conceptual lumped model like TANK.

• Journal of Korea Water Resources Association
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• v.53 no.10
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• pp.845-859
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• 2020

Climate change and recent heat waves have drawn public attention toward other environmental issues, such as water pollution in the form of algal blooms, chemical leaks, and oil spills. Water pollution by the leakage of chemicals may severely affect human health as well as contaminate the air, water, and soil and cause discoloration or death of crops that come in contact with these chemicals. Chemicals that may spill into water streams are often colorless and water-soluble, which makes it difficult to determine whether the water is polluted using the naked eye. When a chemical spill occurs, it is usually detected through a simple contact detection device by installing sensors at locations where leakage is likely to occur. The drawback with the approach using contact detection sensors is that it relies heavily on the skill of field workers. Moreover, these sensors are installed at a limited number of locations, so spill detection is not possible in areas where they are not installed. Recently hyperspectral images have been used to identify land cover and vegetation and to determine water quality by analyzing the inherent spectral characteristics of these materials. While hyperspectral sensors can potentially be used to detect chemical substances, there is currently a lack of research on the detection of chemicals in water streams using hyperspectral sensors. Therefore, this study utilized remote sensing techniques and the latest sensor technology to overcome the limitations of contact detection technology in detecting the leakage of hazardous chemical into aquatic systems. In this study, we aimed to determine whether 18 types of hazardous chemicals could be individually classified using hyperspectral image. To this end, we obtained hyperspectral images of each chemical to establish a spectral library. We expect that future studies will expand the spectral library database for hazardous chemicals and that verification of its application in water streams will be conducted so that it can be applied to real-time monitoring to facilitate rapid detection and response when a chemical spill has occurred.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.1
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• pp.76-87
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• 2019

The purpose of this study was to evaluate the performance of and to derive future maintenance-management measures of the constructed alternative habitat for the Kaloula borealis at the University of Seoul, examining the period between 2015-2017. The research was constructed in 2014 and in a $191m^2$ area. The performance evaluation was divided into maintaining the habitat of the target species, maintaining the population and reproduction rates of the target species, maintaining the habitat of the wild species, the resilience of natural ecosystems, and the harmony with the surrounding environment. In terms of maintaining the habitat of the target species, soil collected from the existing habitat of the Kaloula borealis and was the depth was increased to 30cm in the alternative habitat. An artificial water supply was required every year during the supporting the spawning and hatching of other amphibians along with the Kaloula borealis. The sources of water of the alternative habitat were both rain and tap water, as it cannot be maintained naturally. Additionally, the Kaloula borealis thrived because it inhabited the research site and the average temperature was $26.2^{\circ}C$ from April-June, which is when the Kaloula borealis spawns. In terms of maintaining the population and reproduction rates of the Kaloula borealis, they were evaluated to have stable rates of reproduction. In terms of maintaining the habitat of the wild species, studies on vegetation and the structure of the characteristics of prey or predators will be needed. Also, alien species, such as Humulus japonicus and Bidens frondosa needed to be removed to maintain the wetland ecosystem of the wild species. In the assessment of the resilience of the natural ecosystems, the mud was monitored, noting the changes in the depth of water, with steps taken to reduce the leakage of water. The mud collected from the Haneul Pond wetland, which is located around the research site was piled up. Also, partial mowing management and the inducement of a natural vegetation colony was required for vegetation management. It was also necessary to create porous spaces, such as old trees and tree branches to create a habitat with hiding places and feeding and spawning places for small organisms. In terms of the harmony with the surrounding environment, the following threat factors needed to be managed: amphibian roadkill by vehicles and pedestrians and artificial draining due to nearby user access. Based on the monitoring results, alternative habitat management measures presented the promoting various waterside structures, in which amphibians can spawn and hide in, managing the water environment consistently, managing the vegetation, focused on the habitat of the wild species, and managing the surrounding environment for the habitat. The creation of an alternative habitat should be managed through monitoring, reflecting the characteristics of the changes in the site. Also continuing efforts are also needed to improve the habitat of the target species.

• Korean Journal of Organic Agriculture
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• v.22 no.1
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• pp.97-113
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• 2014

An actual proof experiment was carried out to establish the production of high quality organic rice at farm household in Gwangjin, Junnam, Korea 2011. Experimental plot was designed with conventional organic cultivation and manual organic cultivation in both Hopeongbyeo and Onnuri varities. Experimental field was consisted with suitable drainage loam soil, anryong series, and normal paddy field. Chemical characteristics of the soil were investigated from initial soil and soil after harvest in experimental sites. Seed disinfection was treated with hot water dipping method at $60^{\circ}C$ for 10 min. Rice transplanting was carried out at 17 June with 25 days seedling using machine transplanting. Golden apple snail was used to prevent weed growth as middle size (1.5~1.7 kg/10a) at one week after rice transplanting. Amount of applied fertilizer in experimental plot was supplied with organic fertilizer for the shortage after harvest of hairy vetch (1,100 kg/10a). Bordeaux mixture was used to control of sheath blight and neck blast disease in all experimental plot at 19 Aug. Application of chitin culture solution was treated in manual organic cultivation at 2 and 15 Aug. At late growth stage, incidence rate of neck blast was the highest level at Hopyeongbyeo in conventional organic cultivation. Incidence rate of sheath blight in both Hopyeongbyeo and Onnuri was higher in conventional organic cultivation than in manual organic cultivation. Incidence of rice leaf folder was the highest level at Onnuri in conventional organic cultivation. Yield index in manual organic cultivation was increased by 13% and 38% at Onnuri and Hopyeongbyeo, respectively, compared with conventional organic cultivation. Head rice percentage in both Hopyeongbyeo and Onnuri was slightly increased in manual organic cultivation. These results indicate that high quality production of rice organic cultivation could be depending on management of safe fertilization with nutrient content in soil.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.571-577
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• 2018

A gyratory compactor was developed to reflect the field compaction roller, which is commonly used in road construction. Unlike the compaction of the proctor using a conventional impact load, the gyratory compactor simulated the field roller compaction characteristics using the compressive force by the roller weight and the shear force through the rotation of a roller. The purpose of this study was to evaluate the shear stress and density change characteristics during compaction, which are difficult to obtain in the existing compaction process of the proctor, and to utilize it as a basic data for road design. The compaction characteristics of sand and subgrade soils were also analyzed and evaluated using the gyratory compactor. The compaction characteristics obtained using the gyratory compaction are basically the number of gyrations, height of the specimen, compaction density, void ratio, degree of saturation, and shear stress. As the number of gyrations increased, the height of the specimen decreased, the compaction density increased, the void ratio decreased, the degree of saturation increased, and the shear stress tended to increase. The shear stress of the compacted specimens started at 200 kPa in the initial stage of compaction and increased to approximately 330 to 350 kPa at 50 gyrations. The compaction density, degree of saturation and shear stress tended to increase with increasing water content in the same specimens. Compaction using turning compaction has the advantage of measuring the physical properties required for road design, such as density and shear stress, so that more engineering road design will be possible if it is reflected in road design.

• Journal of Wetlands Research
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• v.20 no.2
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• pp.181-189
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• 2018

This study was performed to analyze the dynamics and distributional condition of biological community and to support the basic information about the estuarine ecosystem management by using the intensively surveyed results by each taxon experts around Tamjin river. We analyzed the biological diversity, abundance, correlation among species, and ecological characteristics about 11 taxa groups including vegetation, fish, birds, mammals, etc. in the Tamjin river estuarine ecosystem. We classified vegetation types into 7 physiognomic types and 18 communities according to habitat conditions with the physical environments and salinity. In total, 1125 species including 9 species of endangered species were identified in research area. The species composition and distributional characteristics of each taxon were corresponded to the environmental characteristics of the estuarine ecosystem. Especially, the species diversity and distribution were clearly distinguished in the river according to the difference of the environmental factors such as flow rate, salinity, and soil. Despite the disturbance factors such as barrage and levees, the biodiversity and its distribution were evaluated to be high level under the current environmental conditions. However, loss or reduction of wildlife habitat due to reclamation, embankment, barrage installation and expansion of farmland has been identified as a major threat to the diversity and health of the local ecosystem. The results of this study can be used as a basic data to cope with various development pressure and damage crisis of the whole estuaries including Tamjin river.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.25 no.2
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• pp.23-38
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• 2022

This study investigates the characteristics and physical habitat requirements for each Bufo gargarizans life history through a literature survey. After deriving variables for each component of Bufo gargarizans, in order to reduce regional deviations from eight previously studied literature research areas for deriving the criteria for variables, a total of 12 natural habitats of Bufo gargarizanss are selected as spatial ranges by selecting four additional sites such as Umyeonsan Ecological Park in Seoul, Wonheungibangjuk in Cheongju in the central region, Changnyeong Isan Reservoir in the southern region, and Mangwonji in Daegu. This study presents Bufo gargarizans SI, a species endemic to Korea, whose population is rapidly declining due to large-scale housing site development and road development, and develops a Bufo gargarizans HSI model accordingly to improve the function of the damaged Bufo gargarizans habitat and to present an objective basis for site selection of alternative habitat. At the same time, it provides basic data for adaptive management and follow-up monitoring. The three basic habitat requirements of amphibians, the physical habitat requirements of Bufo gargarizans, synthesized with shelter, food, and water, and the characteristics of each life history, are classified into five components by adding space and threats through literature research and expert advice. Variables are proposed by synthesizing and comparing the general characteristics of amphibians, among the previously studied single species of amphibians, the components of HSI of goldfrogs and Bufo gargarizans, and the ecological and physical environmental characteristics of Bufo gargarizans. Afterwards, through consultation with an amphibian expert, a total of 10 variables are finally presented by adjacent forest area(ha), the distance between spawning area and the nearest forest land(m), the soil, the distance from the wetland(m), the forest layered structure, the low grassland space, the permanent wetland area(ha), shoreline slope(%), PH, presence of predators, distance from road(m), presence or absence of obstacles. n order to derive the final criteria for each of the 10 variables, the criteria(alternative) for each variable are presented through geographic information analysis of the site survey area and field surveys of the previously studied literature research area. After a focus group interview(FGI) of 30 people related to the Bufo gargarizans colony in Cheongju, a questionnaire and in-depth interviews with three amphibians experts are conducted to verify and supplement the criteria for each final variable. Based on the finally developed Bufo gargarizans HSI, the Bufo gargarizans habitat model is presented through the SI graph model and the drawing centering on the Bufo gargarizans spawning area

• Journal of Soil and Groundwater Environment
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• v.7 no.3
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• pp.115-132
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• 2002

To distinguish the anthropogenic inputs from the chemical weathering with water-rock interaction on the chemical compositons of groundwater in Kwangju city, four different water groups were established based on the landuse type, lithology and topology. The sample from greenbelt area belongs to Group Ⅰ, whereas those from green buffer zone, urban area and industrial area belong to Group II, Group Ⅲ and Group Ⅳ, respectively. The geology of this city mainly consists of biotite granite and granitic gneiss. The concentration of main cations is subject to the behavior of feldspars, micas and carbonate minerals. Cl$\^$-/ and NO$_3$$\^$-/ are supplied by anthropogenic inputs such as domestic sewage whose concentration of these anions is highest in the Group Ⅲ samples. With the Piper diagram, the groundwaters of Group Ⅲ are mainly plotted in CaSO$_4$-CaCl$_2$ type, whereas those of other groups are plotted in Ca(HCO$_3$)$_2$ type, The calculation for the activities of ions and saturation indices of some minerals shows that most of the minerals are undersaturated and plotted in the area of equlibrium with kaolinite. Three factors were extracted from the factor analysis for chemical data. Factor 1 controlled by HCO$_3$$\^$-/, Ca$\^$2-/, SO$_4$$\^$2-/, Mg$\^$2+/ and Na$\^$+/, explains the dissolution of carbonate minerals. mica and plagioclase. Factor 2, controlled by Cl$\^$-/ and NO$_3$$\^$-/, explains the influence of artificial pollution. Factor 3, controlled by Mn, Fe and Zn is subject to the industrial waste water, but the evidence is not clear. Factor 1 is dominant in the Group I and II, indicating that those samples are subjected to natural chemical weathering, The higher scores of factor 2 in the Group Ⅲ samples indicate the potential artificial pollution.