• Journal of the Korean Geographical Society
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• v.45 no.1
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• pp.184-200
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• 2010

The production period of Daedongyeojijeondo is estimated from 1861 to 1866 in consideration of place names. Daedongyeojijeondo is elaborated enough that there are the latest data in, especially is better than Haejwajeondo that is a representative map in the 19th century in marking distance. Daedongyeojido is an official map for national defense and administration, on the other hand Daedongyeojijeondo is a popular map in which social and economical contents are included. The recognition of mountains and rivers based on organic view of the land is also represented in Daedongyeojijeondo, and the principle of the whole of mountains and rivers is well reflected. It is far better than modem maps in the expression of road system and distances, tidal area in rivers.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.173-181
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• 1993

Under natural conditions, rivers do not in general take straight courses but instead take winding courses. This is known as meandering of rivers. Meandering of rivers are so complicated because of the mutual interactions between flow and movable boundaries. In quantitative information, it is important to predict the future location of a river channel(channel migration) because in selecting a bridge site or a location of a road. It may be valuable to know the future impact of a nearby river on those structures. When the prediction model of the migration of channel is used in domestic rivers with high coefficient of river regime, it is rational to use the periodical dominant discharge (PDD), which is named firstly by the author, instead of the average discharge. According to the analysis of the erosion coefficient, the mean deviation on the channel migration, and the bed scour factor, it can bring shedding light on the fact that the discharge is one of the dominant components in channel migration. In project area, the discharge that can shift the channel is slightly greater than 6,000CMS. The prediction model of the migration of channel estimated the erosion coefficient, $E_0$ by the data from the South Han River. This estimated value from the South Han River was also used to predict the migration of the South Han River in year 2000.

• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.311-319
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• 2008

To understand the relative immigration activities (RIA) of hibernal diatom community in Lake Ilgam (at the station with and without macrophyte) and River Han (at the station with different current and nutrient), a natural and artificial bed substrate was deposited from 15 to 29 January 2008. For the study period, both waters comprised huge biomass of diatom, over 75% of total abundance. Nutrients in water column, ash-free dry matter (AFDM) and chlorophyll-a (Chl-a) concentration in substrates were decreased with increasing of current in rivers, while in lakes the macrophyte largely affected the diatom community and water quality. Algal RIA in rivers was high at stations with high concentration of nutrient, AFDM and Chl-a, and in high nutrients and no macrophytes in lakes, respectively. The species showing a higher RIA was Nitzschia amphibia in rivers and Aulacoseira italica in lakes, while the dominant species were Navicula sp. in rivers and Syndera acus in lakes, suggesting no relationship between water algal biomass and its RIA. These results suggest that the RIA of stream diatom community depends exclusively on the current, while the planktonic diatom in lake was of the macrophyte.

• Journal of Korea Water Resources Association
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• v.38 no.5 s.154
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• pp.333-343
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• 2005

The upwind model is well known to simulate shockwaves, but it is rarely applied to natural rivers because of problems caused by the source terms. Although several methods have been developed to deal with the source terms, none of them has been applied to natural rivers. This paper deals with application of the upwind model to the natural river. An implicit upwind model is applied to a hypothetical irregular channel and a natural river with highly irregular bed, width, and hydraulic structures. Different types of the flows including steady-state flow, flood wave, dam-break wave, and bore are simulated to test accuracy and applicability of the implicit upwind model. It is proved that the model can simulate various types of flows in natural rivers with high accuracy and robustness.

• Fisheries and Aquatic Sciences
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• v.8 no.4
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• pp.220-227
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• 2005

The estrogenic phenolic compounds, nonylphenol (NP), octylphenol(OP), bisphenol A (BPA) and nonylphenol mono- and diethoxylate ($NP_{1-2}EO$) were analyzed in 24 surface water samples from six rivers flowing into Masan Bay. All of the phenolic compounds were detected in all six rivers in high concentrations. The most abundant compound was $NP_{1-2}EO$ (86.0%), followed by NP ($10.1 \%$), BPA ($3.6\%$) and OP ($0.3\%$). The levels of phenolic compounds were 1.42-22.70 ${\mu}g$/L for $NP_{1-2}EO$, 0.15-1.68 ${\mu}g$/L for NP, 0.024-0.610 ${\mu}g$/L for BPA and 0.003-0.067 ${\mu}g$/L for OP. Especially, high concentrations were recorded in the rivers that pass through industrial complexes. The concentrations of phenolic compounds observed in these river waters were 1-2 orders of magnitude lower than the reported acute toxicity levels (hundreds of micrograms per liter). However, they were only slightly lower than the chronic toxicity levels. Most of the water samples also exceeded the Canadian nonylphenolic compounds water quality guideline, 1 ${\mu}g$/L, for the protection of aquatic life and the maximum permissible concentrations (MPC), 0.33 ${\mu}g$/L for NP and 0.12 ${\mu}g$/L for $NP_{1-2}EO$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.3
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• pp.209-213
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• 1976

Spinous loaches widely distributed in Korea, are of many color pattern types, but interestingly the crossband B and C-types of these coaches are collected only in the two rivers, the Yeongsan River and the Seomjin River, flowing through the south-western part of Korea. These two types have not only different color pattern, but also different geographical distribution: the B-type is found in the Yeongsan River and the C-typs, in the Seomjin River. But the both types have four common distinctive features, which easily distinguish them from other already known species of this genus: the B and C-types have the similar total length distribution, the same structure of lamina circularis and scales, and the black spots at the back of their opercula. These peculiarities may be explained by studing the history of these two rivers. The author considers that they are once rivers of the same origin located around the Noryeong and the Sobaeg Mountains, and then were eventually separated from each other as the water level or the crust of Korea peninsula changed. Thus, these two types, B and C, of spinous loaches should have been the same species living in the same river, but in the course of time, these two types have taken different color patterns since the separation of two rivers thus making them impossible to cross between these two populations.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.875-885
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• 2019

The expansion of riparian vegetation in middle size rivers in Korea had been analyzed in this study. Seom River with dam, Cheongmi River without dam, and Naesung River with no operating dam in the upstream was investigated for the 1 km to identify the expansion of riparian vegetation through the aerial photograph analysis. As a results, we found that the rate of vegetation area is 54.7% in Seom River, 77.5% in Cheongmi River, and 49.7% in Naesung River. The vegetation area had been increased in 3 rivers, and the expansion rate since 2010 is very high nearly up to 2 times (17 times in Naesung River). Sandbar and open-water area, however, have been decreased in the same rate with the riparian vegetation expansion. It could be concluded that vegetation increase trend is clear in rivers regardless of location and dam existence. Further researches are necessary to find out the causes to establish the countermeasures because the increase of vegetation will change the physical system as well as biological system of river.

• Fisheries and Aquatic Sciences
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• v.22 no.7
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• pp.15.1-15.8
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• 2019

Corexit 9500 is a dispersant commercially available in Nigeria that is used to change the inherent chemical and physical properties of oil, thereby changing the oil's transport and fate with potential effects on the environment. The aim of this study was to assess the biochemical (enzymes and electrolyte) toxicity of Corexit 9500 dispersant on the gills, liver and kidney of juveniles of Clarias gariepinus after exposure for 21 days. One hundred sixty fish were used without gender consideration. Range-finding tests were conducted over a 96-h period after acclimatisation of the test organisms in the laboratory. The test organisms (10/treatment) were exposed to Corexit 9500 in the following concentrations-0.00, 0.0125, 0.025 and 0.05 ml/l in triplicate. Twenty-one days later, fish was dissected. 0.5 g from each of the following organs-gills, liver and kidney tissues-was removed, homogenised and tested for enzymes [superoxide dismutase (SOD), catalase (CAT), alanine aminotransferase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP)], urea, creatinine and electrolytes (sodium ($Na^+$), potassium ($K^+$), chloride ($Cl^-$), bicarbonate ($HCO_3{^-}$)) following standard methods. In the gills, SOD and ALT to AST ratio were significantly lower than in control while the creatinine was significantly higher in the toxicant. In the kidney, creatinine was significantly higher in fish exposed to the toxicant. In the liver, ALP increased in the toxicant while urea was decreased. The mean electrolyte concentrations ($Na^+$, $K^+$, $Cl^-$ and $HCO_3{^-}$) increased significantly in the concentration of the toxicant (P < 0.05). The alterations observed in the activities of these electrolytes and enzymes indicated that Corexit 9500 interfered with transamination and metabolic functions of the fish.

• Journal of Soil and Groundwater Environment
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• v.27 no.5
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• pp.1-9
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• 2022

A correlation analysis was performed to investigate differences in the response of surface water and groundwater to drought using the Standardized Precipitation Index (SPI). Water level data of 20 agricultural reservoirs, 4 dams, 2 rivers, and 8 groundwater observation wells were used for the analysis. SPI was calculated using precipitation data measured at a nearby meteorological station. The water storage of reservoirs and dams decreased significantly as they responded sensitively to the drought from 2014 to 2016, showing high correlation with SPI of the relatively long accumulation period (AP). The responses of rivers varied greatly depending on the presence of an upstream dam. The water level in rivers connected to an upstream dam was predominantly influenced by the dam discharge, resulting in very weak correlation with SPI. On the contrary, the rivers without dam exhibited a sharp water level rise in response to precipitation, showing higher correlation with SPI of a short-term AP. Unlike dams and reservoirs, the responses of groundwater levels to precipitation were very short-lived, and they did not show high correlation with SPI during the long-term drought. In drought years, the rise of groundwater level in the rainy season was small, and the lowered water level in the dry season did not proceed any further and was maintained at almost the same as that of other normal years. Conclusively, it is confirmed that groundwater is likely to persist longer than surface water even in the long-term drought years.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4265-4271
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• 2022

Determination of ¹³⁷Cs, ⁴⁰K and ²¹⁰Po in water, bottom sediments and suspended matter of river systems of the Can Gio Biosphere Reserve, Vietnam was carried out. The average activity concentration of ¹³⁷Cs in waters of Ca Gau and Long Tau was 0.89 ± 0.14 and 1.08 ± 0.15 Bq m^-3 and was comparable to the levels of this radioisotope in waters of the East Sea. The activity concentration of ¹³⁷Cs in bottom sediments was 2.23 ± 0.81 and 3.63 ± 1.24 Bq kg^-1. The activity concentration of ¹³⁷Cs in water and bottom sediments could be characterized as low. So, the water areas of the Ca Gau and Long Tau rivers could be attributed to areas with insignificant pollution by technogenic radionuclides. The ²¹⁰Po activity concentration in bottom sediments of the Ca Gau and Long Tau rivers ranged from 9.2 ± 1.2 to 25.5 ± 2.1 Bq kg^-1, which is typical for river bottom sediments. Such values indicate the absence of anthropogenic enhancement of the entry of this radionuclide into the Can Gio river systems. The ⁴⁰K activity concentration varied within 467 ± 42-651 ± 39 Bq kg^-1 and represented typical values of potassium content in the bottom sediments of coastal water bodies, subject to a significant influence of the lithogenic component of suspended matter.