• Microbiology and Biotechnology Letters
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• v.27 no.2
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• pp.159-165
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• 1999

Pseudomonas aeruginosa JRT-4 strain was used as a biosurfactant-producing microorganism in this study. It was one of the microorganisms isolated from the sewage sludge, the main and branch streams of Han river. The surface tension of the culture broth of P. aeruginosa JRT-4 decreased to 30mN/m. The crude biosurfactant was obtained from the culture broth by acid precipitation, solvent extraction, evaporation, and freeze drying. The CMC value of the crude biosurfactant was 0.006%(w/v). From analysis of the chemical structure of biosurfactant, it was determined as rhamnolipid 1 and 3 structures by FAB mass spectrometer. In the washing test for artificially contaminated textiles, the biosurfactant showed better bleachness than the two chemically synthesized surfactant, LAS and SLES. Finally, the biodegradation and ecotoxidolorical tests showed that the biosurfactant was readily biodegradable in the environment and a mild material for microorganisms and green algae.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.604-609
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• 2005

Runoff characteristics of organic matters and nutrients from greenhouse site in paddy field area were investigated during the irrigation period in 2004. The greenhouse selected which situated near the Nam river, Jinju, Korea used the ground water as the irrigation purpose. And, the rotating system of paddy field to upland was adapted as a cropping system which is a typical practice in this area. Various items such as total phosphorus(T-P), total nitrogen(T-N), dissolved oxygen(DO), BOD, etc. were observed to figure out the seasonal and spatial variation in the study sites. it was found that the risk of water pollution due to the contamination of nutrients in canals in green house sites, and their neighbouring small sized streams are much higher than those in ordinary paddy field areas. Further surveys and investigations are required to find out the counter measures to reduce water pollution occurred in greenhouse sites.

• KIEAE Journal
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• v.11 no.3
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• pp.3-9
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• 2011

For urban development, natural covering area such as urban green or river is more rapidly reducing than artificial surface covering area like concrete or asphalt, so thermal environment in a city is being drastically deteriorated. Recently, since people recognize the importance of parks or rivers in a city which play roles as an environmental buffer in it, many studies and policies consider how to improve the life quality of citizens and urban environment. This study aims to examine the status of thermal environment variation in the parks and rivers of the city which is the subject of this research and provide foundational data for urban environment plans through research on temperature variation rate and temperature controlling effect.

• Journal of the Korean Geophysical Society
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• v.6 no.4
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• pp.245-259
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• 2003

Two multichannel analysis of surface wave (MASW) surveys were conducted over a soil site in Tacoma Water's Green River Facility, Washington, where construction of a chemical treatment facility had been planned. The purpose of the surveys was to compare soil stiffness characterized by shear-velocity (Vs) distribution before and after Deep Dynamic Compaction (DDC) operation that was designed to improve the soil stiffness. Site soil consisted of very heterogeneous gravel and cobbles in a sand-and-silt matrix. Results from each survey are represented by two 2-D Vs maps delineating Vs variation of soil below the surveyed lines. One map was constructed from those dispersion curves that were analyzed with a significant amount of subjective judgment involved, whereas the other map was constructed from those dispersion curves analyzed with as much objective information as possible. Comparison of 2-D Vs maps indicates that Vs actually decreased after the DDC operations, possibly due to the loss (or reduction) of cohesive bonding between soil particles caused by the compaction operations.

• Animal cells and systems
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• v.3 no.1
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• pp.17-21
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• 1999

A new species of gudgeon, Microphysogobio rapidus is described from 25 specimens collected from the Naktong River system, Korea. The new species is similar to Microphysogobio yaluensis but is distinguished from the latter and congeners by the combination of the following characteristics: number of papilla on the upper lip, 4.5 scales above the lateral line, short distance from the anus to the origin of the anal fin, wide scaleless area of the abdomen, nuptial colour consisting of a longitudinal green stripe on the lateral side of the body and bright blue colour of the suborbital region and operculum. A key to the species of Microphysogobio from Korea is also included.

• Journal of Environmental Impact Assessment
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• v.28 no.3
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• pp.245-262
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• 2019

The objectives of this study were to construct a three-dimensional water quality model (EFDC) for the river reach between Chilgok Weir and Gangjeong-Goryong Weir (GGW) located in Nakdong River, and evaluate the effect of hydraulic changes, such as water level and flow velocity, on the control of water quality and algae biomass. After calibration, the model accurately simulated the temporal changes of the upper and lower water temperatures that collected every 10 minutes, and appropriately reproduced changes in organic matter, nitrogen, phosphorus, and cyanobacteria. However, the simulated values were overestimated for the diatoms and green algae cell density, possibly due to the uncertainties of the parameters associated with algae metabolism and the lack of zooplankton predation function in the simulations. As a result of scenario simulation of running the water level of GGW from EL. 19.44 m to EL. 14.90 m (4.54 m drop), Chl-a and algae cell density decreased significantly.In particular,the cyanobacteria on the surface layer, which causes algal bloom, declined by 56.1% in the low water level scenario compared to the existing management level. The results of this study are in agreement with the previous studies that maintenance of critical flow velocity is effective for controlling cyanobacteria, and imply that hydraulic control such as decrease of water level and residence time in GGW is an alternative to limit the overgrowth of algae.

• Ecology and Resilient Infrastructure
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• v.10 no.2
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• pp.31-39
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• 2023

NNbF is a newly emerging approach to reduce flood risk in coastal and fluvial areas using natural features or engineered nature-based features with the expectation of co-benefits of provisional, regulating, and socio-cultural services provided by the ecosystem. NNbF is not quite different from existing, related terms based on nature, such as NbS, Eco-DRR, NI, GI, EwN, and BwN, for all these terms include expectation of benefits for human societies by directly utilizing or mimicking nature's ecological functions. If we focus on the comprehensiveness of each term's subject and object, we can say that NbS > NNbF > (Eco-DRR, NI/GI). Among the 18 measures introduced in the NNbF International Guideline in the river and floodplain management category, it was found that measures of wash lands and floodplain restoration, including levee setback/removal and side-channel restoration, seemed to be the most applicable to rivers in Korea. These selected measures could be more effective when river managers purchase riparian lands along river courses by relevant laws for river water-quality protection.

• Ecology and Resilient Infrastructure
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• v.10 no.4
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• pp.135-142
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• 2023

A various technology of remote sensing and image analysis are applied to study landscape changes and their influencing factors in stream corridors. We developed a method to detect landscape changes over time by calculating the optical index using multispectral images taken from satellites at various time points, calculating the threshold to delineate the boundaries of water bodies, and creating binarized maps into land and water areas. This method was applied to the upstream reach of the weirs in the Geumgang River to track changes in the sandbar formed by the opening of the weir gate. First, we collected multispectral images with a resolution of 10 m × 10 m taken from the Sentinel-2 satellite at various times before and after the opening of the dam in the Geumgang River. The normalized difference water index (NDWI) was calculated using the green light and near-infrared bands from the collected images. The Otsu's threshold of NDWI calculated to delineate the boundary of the water body ranged from -0.0573 to 0.1367. The boundary of the water area determined by remote sensing matched the boundary in the actual image. A map binarized into water and land areas was created using NDWI and the Otsu's threshold. According to these results of the developed method, it was estimated that a total of 379.7 ha of new sandbar was formed by opening the three weir floodgates from 2017 to 2021 in the longitudinal range from Baekje Weir to Daecheong Dam on the Geumgang River. The landscape detection method developed in this study is evaluated as a useful method that can obtain objective results with few resources over a wide spatial and temporal range.

• Korean journal of food and cookery science
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• v.7 no.1
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• pp.67-80
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• 1991

This study researched the dietary habit of boy's and girl's high school students, and into low it was connected with the state of health between the group of having the right dietary habit and the group of having the wrong habit. Results were as follows: 1. The age about the object person of research was the most numerous in 79% at 16~17 years old, the average weight was $55.67\pm9.08$kg, the average height was $165.47\pm7.56$cm. 2. In the parent's school career of the object person of research, persons who graduated high school were many. The mother's educational level was lower than the father's school career. The parent's school career in the district south of a river was higher than the parent's school career in the district north of a river. And the parent's school career of cultural students was high. 3. The frequency of food intake in the district north of a river and in the district south of a river was a meaningful difference in the vegetables blended in green and yellow things (p<.01), fruit (p<.05), rice, flour, potatoes (p<.05), and so the district north of a river took less than the district south of a river. 4. The most regular diet in a day was lunch. The appetite of the students was generally good. 5. The general environment and state of health were a meaningful difference about melancholia (p<.05) in the district of north and south of river, and so melancholia in students of the north of a river was high. 6. The state of health according to regular diet was a meaningful difference, so regular student was better than irregular student in state of health, and was the same in study. 7. Eating habit correlated much to each state of health, Especially in physical health, the muscular frame correlated to fruit (p<.001), seaweeds (p<.05), fried food, jun, panbroiled food (p<.05), salty taste (p<.05), sour taste(p<.001).

• Korean Journal of Ecology and Environment
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• v.49 no.3
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• pp.153-175
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• 2016

Daecheong Reservoir has suffered eutrophication and water-blooms by blue-green algae from initial impoundment, and algae alert system (AAS) was introduced in 1997. The purpose of this study was to investigate the effect of rainfall and hydrological factors in increase or decrease variability of green-tide and prolonged AAS, studied and analyzed the current situation of AAS has been operating for 19 years (1997~2015) in Daecheong Reservoir. The total issued number of AAS was 46 times, the most frequent period in August and September were 22 times (752 days) and 16 times (431 days), respectively, it accounted for 82.6%. Many number and frequency during this period were significantly associated with rainfall, various discharge and water level. Rainfall and hydrological events are associated with the rainy season of monsoon-Changma and the typhoon, it was concentrated in June~September, total rainfall in this period accounted for 69.9% of the annual rainfall. An increase in inflows was dependent on the intensity, frequency and the amount of rainfall. Accounted for 68.4% of the total annual inflow, it was a time when the most rapidly changing hydrological variability in the reservoir. The total outflow was closely related to rainfall, and compared the distinctive characteristics of hydropower generation and watergate-spillway discharge. In addition, the upreservoir zone of Daecheong Reservoir could be vulnerable to green-tide by regulating discharge of the upstream dam. The issue of AAS was strongly related to the with and without of watergate-spillway discharge. The watergate-spillway discharge had a total of 25 times, it was maximum 17 days from July to September in the year. And the opening times and each duration of the watergate were 1~4 times and the range of 3~37 days, respectively. When the watergate opened, the issue of AAS was maintained to 13 years and the movement of water bodies and green-tide was great about five times than that of non-open, had a profound effect on prolonged AAS within reservoir. In Daecheong Reservoir, Chusori (CHU) area of the So-ok Stream was still showing serious symptoms green-tide levels in the summer, but Janggye (JAN) waters of the main reservoir was pointed out that more important. AAS will be operated by an absolutely consider the rainfall and hydrological effects around the watergate-spillway discharge. The measures of green-tide will be included in the limnological studies more suited to the characteristics of the watershed and reservoir of the our country. Finally, from now on, we will prepare the systematic management and guidelines for vulnerable zone water-blooms that are the source within the reservoir before the monsoon rather than waiting for the arrival of green-tide on the operating stations of AAS.