• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.188-191
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• 2008

The Tonle Sap, Cambodia, is a huge lake and periodically flooded due to monsoon climate. The incoming water causes intensive flooding that expands the lake over vast floodplain and wetland consisting mainly of forests and shrubs. Monitoring the water-level change over the floodplain is essential for flood prediction and water resource management. A main objective of this study is flood monitoring over Tonle Sap area using ALOS PALSAR. To study double-bounce effects in the lake, backscattering effect using ALOS PALSAR dual-polarization (HH, HV) data was examined. InSAR technique was applied for detection of water-level change. HH-polarization interferometric pairs between wet and dry seasons were best to measure water level change around northwestern parts of Tonle Sap. The seasonal pattern of water-level variations in Tonle Sap studied by InSAR method is similar to the past and altimeter data. However, water level variation measured by SAR was much smaller than that by altimeter because the DInSAR measurement only represents water level change at a given region of floodplain while altimeter provides water level variation at the central parts of the lake.

• 한국유체기계학회 논문집
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• 제13권1호
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• pp.23-28
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• 2010

A draft tube which has impeller to elevate bottom water and spread it over surface of lake water, induces convective circulation of lake water, a Long-Distance Circulation (LDC). Circulation of lake water make stratified water mixed and enhance DO (Dissolved Oxygen) of bottom water. Circulation rate of water is determined by draft rate of the tube, which is dependent on design parameters of the draft tube system, i. e. dimension of impeller and diffuser, inclined angle of impeller, impeller shape, and rotational speed. In this study, change in draft rate and power consumption of circulation equipment was investigated numerically with changing impeller dimension, angle and rotational speed. It was found that flowrate of draft water was increased as the dimensions of draft tube and impeller, and rotational speed and inclined angle of impeller increased. The power consumption was also elevated with increasing parameter values, and final selection of parameter values was made to satisfy target flowrates and power consumption.

• 한국물환경학회지
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• 제21권6호
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• pp.584-594
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• 2005

The spatio-temporal abundance pattern of algae in Lake Paldang from 2002 to 2004 was investigated. The concentration of chlorophyll a representing algal biomass had fluctuated intensively throughout the year. Among three years, the highest algal biomass was shown in 2002, and typical growth peak of concentration of chlorophyll a was occurred in spring and autumn. There had been frequent rainfall in spring drought period in 2003 and it resulted in the decrease of the algal biomass. The distribution pattern of four algal groups on the surface water of Lake Paldang showed different abundance by season and by water area. In particular, different algal growth characteristics by water areas were observed. Influences of various environmental parameters on algal abundance in four water areas of Lake Paldang were analyzed statistically. From the results of Peason correlation analysis, it was understood that the kinds and affects of environmental parameters were different according to water areas and seasons. Based on the factors analysis of environmental parameters on the concentration of chlorophyll a, stepwise regression models whose independent variables were the factors produced by factor analysis and dependent variable was the concentration of chlorophyll a were derived by water areas and seasons. As a whole, factors related with organics and photosynthesis were revealed to have high affects to algal abundance, whereas limiting nutrients such as phosphorus and nitrogen showed little affect in Lake Paldang.

• 한국물환경학회지
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• 제33권3호
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• pp.341-347
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• 2017

From 2014 to 2016 water quality survey results according to the location and depth of Youngrang Lake are as follows: Distribution of dissolved oxygen in the water depth was investigated by the middle section and the downstream 1st, 3rd, 5th, when investigating bottem 1m interval anoxic layer. In organic matter and nutrient concentration distribution COD upstream 2.8 mg/L, middle section 4.2 mg/L downstream 4.1 mg/L, more than two times higher in bottem layer and TP concentrations showed a similar trend with COD, upstream of 0.047 mg/L, middle section was 0.051 mg/L, downstream of 0.059 mg/L. There was a difference in salinity every survey period the average salinity is lowest with 28.5‰ when the second survey. And the highest with 32.1‰ in the fourth investigation. Korean trophic state index($TSI_{KO}$) were showed eutrophic conditions in the middle section and downstream else showed mesotrophic state in the entire period. In order to evaluate the cause of water pollution Youngrang lake, regression analysis of the relationship between salinity and DO, COD, TN, TP, Chl-a results, $R^2$ is from 0.63 to 0.95 Youngrang lake water quality was found to have a close relationship with salinity due to inflow of seawater. As a result, in order to improve the quality of Youngrang lake efficient incorporation of the amount of water through the seawater influent as it is considered the key.

• 대한환경공학회지
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• 제22권3호
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• pp.535-546
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• 2000

주암호는 광주 전남지역의 주민생활이나 공 농업활동에 기반이 되는 중요한 수자원의 역할을 하고 있으나, 주암호에 유입되는 오염물질로 말미암아 호수의 수질은 점점 악화되고 있는 실정이다. 주암호의 수질개선대책을 수립하기 위한 예비단계로서 호수의 수질모델링을 실시하여 수질이 장래에 어떻게 변화될 것인지를 확인할 필요성이 있다. 수질모델링 작업에 이용할 수 있는 컴퓨터 프로그램은 여러 종류가 있으나, 각 프로그램에서 요구하는 오염물질 유입량, 수리 수문 등의 압력자료(Input data)는 불확실성을 포함하고 있으며, 이러한 불확실성은 예측결과(장래수질)의 불확실성을 초래하게 된다. 수질모델링에서 불확실성이 발생하는 주요원인은 활용할 수 있는 정보의 부족, 미래상황 및 예측모델의 불확실, 그리고 전문가 지식의 한계 때문이다. 따라서 본 연구의 목적은 퍼지이론을 응용하여 수질예측 모델에서 요구하는 입력자료들의 불확실성 정도를 해석하고, 이를 수질예측 모델에 그대로 결합시킬 수 있는 방법을 개발하는 것이다. 이러한 방법의 적용은 불확실성을 고려하지 않는 방법들에 비해 합리적이고 현실성 있는 주암호의 장래수질을 예측하는데 도움이 될 것이다.

• Fisheries and Aquatic Sciences
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• 제26권4호
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• pp.282-293
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• 2023

Nile perch and Nile tilapia are major commercial species in Uganda, and thus require continuous production. However, their production is impacted by anthropogenic activities such as fishing in breeding habitats. The aim of this study was to identify and characterize Nile perch and Nile tilapia fish breeding habitats on Lake Kyoga. Water quality, lake bottom, fish and vegetation type samples were collected from 20 sites in April of 2021 and 2022. Key informant interviews were conducted with experienced fishermen at five fish landing sites. The water quality parameters indicated significant difference within the sites using analysis of variance. Sandy and muddy bottom types were equally spread at 40% each by use of a pie chart. Fish gonads showed no significant difference among the 20 sites. Bivariate correlation analysis of the vegetation types indicated a strong negative correlation with Nile perch while Nile tilapia had a positive correlation. Principal component analysis of the water quality, fish gonads and habitat vegetation components cumulatively contributed 82.5% in characterizing a fish breeding habitat. Four sites for Nile perch and four sites for Nile tilapia were characterized as breeding sites on Lake Kyoga and are recommended for mapping and gazettement as breeding habitats for sustainable fisheries management.

• 한국물환경학회지
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• 제26권1호
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• pp.71-80
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• 2010

We studied the nitrogen behavior and budget of Lake Paldang from March to December 2008. The particulate nitrogen (PN) concentrations ranged from 7 to 13% of the total nitrogen concentration (TN) in the stream inflows, the downstream outflow, and the lake water. The nitrate nitrogen ($NO_3-N$) concentration ranged from 67 to 78% of the TN. In the three rivers of Lake Paldang, Gyeongan River (In3 site) had the highest average of the TN, 5.037 mgN/L, but North Han River (In2 site) had the lowest average TN, 1.683 mgN/L. South Han River (In1 site) had the average TN of 2.399 mgN/L. In the dam discharge, TN showed the average 2.063 mgN/L. In the lake water, L4 site (Gyeongan River area) had the highest average TN, 3.781 mgN/L, but L3 site (North Han River) had the lowest average TN, 1.587 mgN/L. Total input of nitrogen loads to Lake Paldang was about 30,875 ton/year in 2008. Inflow rivers contributed 30,643 ton/year (South Han River: 18,111 ton/year (59%), North Han River: 11,333 ton/year (37%), and Gyeongan River: 1,199 ton/year (4%)). The atmospheric deposition had 135 ton/year, the nitrogen release from the bottom sediments had 88 ton/year, and macrophytes had 9 ton/year. Total output of nitrogen loads from Lake Paldang was about 31,256 ton/year. The downstream from dam contributed 29,877 ton/year, and the sediment deposition was 1,379 ton/year.

• 생태와환경
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• 제46권1호
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• pp.128-134
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• 2013

In the summer season (June~August) during the study period of Lake Doam, average concentrations of major water quality parameters, COD, SS, TN, and TP were 4.0, 16.2, 3.129 and $0.077mg\;L^{-1}$, respectively, and Chl-a was $11.8mg\;m^{-3}$. The result has indicated that Lake Doam was a meso-eutrotrophic lake. Lake Doam data from the summer season (June~August), precipitation from 2001 to 2012, and water quality (COD, SS, TN, TP, Chl-a etc.) of seven years (2001, 2002, 2004 and 2009~2012), were statistically analyzed for long-term trends by Mann-Kendall test and Sen's slope estimator methods. The statistical results showed that precipitation, SD, COD, TN, $NO_3-N$, $NH_3-N$ and Chl-a had decreasing trends, and EC, turbidity, SS, TP and DIP had increasing trends. Suspended solids and total phosphorus were directly affected by precipitation. In the case of suspended solids, more aggressive and constructive plans need to be implemented than the current turbidity reduction project to achieve the targeted water quality ($5mg\;L^{-1}$ of SS) in Lake Doam. In particular, we need to specify a project that considers the steep topographic characteristics of high, land farming areas and precipitation conditions of the Lake Doam watershed, which can increase the efficiency of a turbidity reduction project.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.179-184
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• 2011

The development of new energy has attracted consideration attention due to the high oil price and environmental problems. In advanced country, they have tried to carry out a long range plan for energy. We need to develop new energy for Low Carbon Green Growth in Korea. The building is 30% among ratio of energy consumption in Korea. And in the past, heating energy was high ratio for energy using at home. But recently, the demand for cooling energy keeps growing due to rising average temperature on the earth and improvement of life quality. In this situation, the energy of lake water and ocean water has studied to utilize in advanced country because of low temperature at underwater. But the study for deep water is still a lot left to do. In this study, we analyzed district cooling system and the present condition. Analyzing the deep lake water cooling system in Toronto, we found an application of district cooling system using deep ocean water. Deep lake water uses heat source for district cooling and water source for city in Toronto. So reducing the initial cost, this city had economic effect. When DLWC was applied at existing building, the heat exchanger was installed instead of cooling tower and refrigerator. And the heat exchanger used to connect main pipe with cool water on city. System using deep ocean water can be applied as a similar way to supply cool water from lake to building.

• 한국물환경학회지
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• 제39권1호
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• pp.20-29
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• 2023

This study analyzed the relationship between harmful cyanobacterial abundance and environmental factors in order to figure out the causes of the recent increase of cyanobacteria in Lake Dukdong from 2019 to 2021. Lake Dukdong, which is used as a drinking water source for Gyeongju City, has an algae alert system in place. Lake Dukdong has maintained good water quality, but algae alert level 1 (over 1,000 cells/mL) has been issued in recent years. As a result of Pearson correlation analysis (from May to Oct.), the cell density of Microcystis and Aphanizomenon, which form part of the most harmful cyanobacteria genus, were significantly positively correlated with the water temperature and water storage volume. T-test was performed to compare the data from 2016-2018 and 2019-2021 (from May to Oct.). The average density of harmful cyanobacteria cells increased about six-fold from 54 to 344 cells/mL. There were significant differences in water temperature, pH, total nitrogen (TN), total phosphorus (TP), TN/TP ratio, water storage volume, and cyanobacterial cell density. Water temperature increased from 19.2 to 22.8 ℃. TP concentration increased from 0.017 to 0.028 mg/L. The main cause of the recent increase of harmful cyanobacteria in Lake Dukdong is thought to be the increase in water temperature, TP concentration, and water storage volume from 2019 and 2021, resulting in more favorable conditions for cyanobacterial growth.