• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.386-390
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• 2006

In this study, the analysis of river naturalness and water quality were executed in the major rivers of the Nakdong River Basin. As a result, the assessment index of the General Evaluation was 1.428 to 4.107 as $1^{st}\;to\;4^{th}$ grades. The River Shape was 2.111 to 4.048 as $2^{nd}\;to\;4^{th}$ grades and the River Environment was 1.774 to 3.238 as $1^{st}\;to\;4^{th}$ grades. As well, evaluation of water quality showed that concentration of hydrogen ion was 7.102 to $8.49mg/{\ell}$, BOD was 0.748 to $5.271mg/{\ell}$, DO was 3.668 to $19.960mg/{\ell}$ and SS was $5.077mg/{\ell}$. The correlation between river naturalness and water quality was analyzed to investigate similarity and independence of river naturalness evaluation index. It was shown that coefficient of correlation was low with value of -0.1503 to -0.5886, therefore, was evaluated as independent.

• Journal of Korean Society on Water Environment
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• v.24 no.3
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• pp.291-296
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• 2008

Pollutant unit load developed by Ministry of Environment (MOE) in 1995 has been a tool commonly used for water quality management and environmental policy decision. In spite of the convenience of the method in application, the shortcoming of the method has been criticized especially for nonpoint source pollution from paddy field. In this paper the estimation procedures of pollutant unit load from paddy field in the major river basins (Han, Nakdong, Geum, and Youngsan river) were investigated, and some suggestions of improvement measures of the unit-load estimation were made. The investigation showed that the distributions of rainfall, run-off, and run-off ratio, which are the most important factors affecting discharge amount of pollutants, were not similar among river basins. Such differences seemed to result in a greater unit loads estimation at Han river and at Nakdong river watersheds compared to the others. Therefore, it is not likely to be rationale to compare unit load among the watersheds without consideration of such differences. We conclude that estimation of unit-load through an intensive monitoring of pollutant discharge is crucial for better estimation of unit-load. When such an intensive monitoring is not easy due to labor and expense restriction, we suggest that unit-load should be estimated based on the storm-events which is a representative rainfall-runoff event of the area.

• Journal of Environmental Science International
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• v.18 no.9
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• pp.971-981
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• 2009

An objective of this study is as follows: 1) performing sensitivity analysis and parameter estimation of RMA2 and RMA4 models for the West-Nakdong River, 2) drawing up alternatives of gates-operation for water-quality enhancement, and 3) quantitative evaluation of methodology of 'flow-restoration by gates-operation' among 'Comprehensive Plan Improving Water-Quality in the West-Nakdong River(WNR)' with the target water-quality(BOD at Nakbon-N point: below 4.3 mg/L). The parameters for the RMA2 (depth-averaged two-dimensional flow model) and RMA4 (depth-averaged two-dimensional water-quality model) were determined by sensitivity analysis. Result of parameter estimation for RMA2 and RMA4 models is $1,000\;Pa{\cdot}s$ of the eddy viscosity, 20 of the Peclet number, 0.025 of the Manning coefficient, and $1.0\;m^2/s$ of the diffusion coefficient. We have evaluated the effects of water-quality enhancement of the selected alternatives by numerical simulation technique with the models under the steady-state flow condition and the time-variant transport condition. Because of no-resuspension from river bottom and considering BOD as conservative matter, these simulation results slightly differ from real phenomena. In the case of $50\;m^3/s$ of Daejeo-gate inflow, two-dimensional flow pn results result represents that small velocity occurs in the Pyungkang Stream and no flow in the Maekdo River. In the WNR, there occurs the most rapid flow near timhae-bridge. In the WNR, changes of water-quality for the four selected simulation cases(6, 10, 30, $50\;m^3/s$ of the Daejeo-gate inflow) were predicted. Since the Daejeo-Gate and the Noksan-Gate can be opened up to 7 days, it would be found that sustainable inflow of $30\;m^3/s$ at the Daejeo-gate makes BOD in the WNR to be under the target of water-quality.

• Journal of Korea Water Resources Association
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• v.35 no.4 s.129
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• pp.397-410
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• 2002

In order to quantitatively identify historical drought conditions and to evaluate their variability, drought indices commonly used. The calculation method for the drought index based on the principal hydrological factors, such as precipitation and reservoir storage, can estimate the duration and intensity of a drought. In this study the Palmer-type formula for drought index is derived for the Nakdong River basin by analyzing the monthly rainfall and meteorological data at 21 stations. The Palmer Drought Severity Index(PDSI) is used for dry land sectors to evaluate the meteorological anomaly in terms of an index which permits time and space comparisons of drought severity. The Surface Water Supply Index(SWSI) is devised for the use in conjunction with the Palmer index to provide an objective indicator of water supply conditions in Nakdong River basin. The SWSI was designed to quantify surface water supply capability of a watershed which depends on river and reservoir water The Standardized Precipitation Index(SPI) is evaluated for various time periods of 1 to 12 months in Nakdong River basin. For the purpose of comparison between drought indices correlation coefficient was calculated between indices and appropriate SPI time period was selected as 10 months for Nakdong River basin. A comparative study is made to evaluate the relative severity of the significant droughts occurred in Nakdong River basin since 1976. It turned out that $'94{\sim}'97$ drought was the worst drought in it's severity. It is found that drought indices are very useful tools in quantitatively evaluating the severity of a drought over a river basin.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.124-138
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• 2003

This paper aimed to analyze the relationship between alga3 bloom patterns and hydrological, limnological data which were collected from major reservoirs in Korea for 8 years (1990${\sim}$1997). Water temperature of river-type reservoirs showed wider seasonal fluctuations than that of lake-type. pH of lake-type reservoirs was low in winter season but high in summer season. In contrast, river-type reservoirs showed high pH in spring and autumn seasons as well, and very low in summer season. COD of lake-type reservoirs and Paldang reservoir was lower (2${\sim}$3 mg/L) than that of Geumgang and Nagdonggang reservoirs (6${\sim}$9 mg/L). Dissolved oxygen (DO) of river-type reservoirs was higher than that of lake-type reservoirs. Seasonal fluctuation pattern of DO saturation in river-type reservoirs was high (80 ${\sim}$100%) and remained relatively constant whereas lake-type reservoirs showed the highest level (93%) in late spring or early summer, which gradually decreased entering winter season(46${\sim}$06%). And monthly variation of DO saturation showed inverse proportion to water volume in lake-type reservoirs. Nutrients concentration in river-type lake is higher than lake-type. Seasonal fluctuation of nutrients (T-N, T-P) in lake-type reservoirs was relatively small than that of river-type reservoirs. Annual mean N/P mass ratio of lake-type reservoirs was higher than that of river-type. Transparency tended to related with the suspended solid concentration in river-type reservoirs. Algal bloom of lake-type and river-type reservoirs occurred at any time except rainfall and winter periods. And it dominated in summer and early autumn, respectively. Algal bloom of river-type reservoirs was higher than that of lake-type. Relationship between rainfall and chlorophyll- a in lake-type reservoirs was relatively high, however river-type reservoirs showed insignificant.

• The Korean Journal of Ecology
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• v.14 no.3
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• pp.345-360
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• 1991

Benthic macroinvertebrates were collecte in the middle reaches of the paenae stream, a tributary of th naktong river in korea, in four seasons from August 1989. To may 1990, during the study period, 125 species, 81 genera and 41 families were collected. Overall, the most dominant species was lepidostoma sp. 1 followed by heptagenia kihada, neoperla quadrata, diamesa sp. 1, ect.. the community was most diverse in autumn, However the number of collectd individuals was highest in winter. Species of chironomids including diamesa sp. 1 and mayflies including paraleptophlebia chocorata were collected exceptionally in a large number in winter. Seasonal occurrence of funtional groups such as collectors, shredders and scrapers was related with the availadlity of food sourses in the stream. The abundance of predators was relatively stable in four seasons with 17% on average. Diversity, tbi and chandler's biotic score(bs) in the paenae strem were 3.75, 14.5, and 100 on average, respectively. Based on biological and chemical indices the paenae stream was clean in the range of xeno- and oligo- saprobity.

• The Korean Journal of Ecology
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• v.14 no.4
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• pp.399-413
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• 1991

Benthic macroinvertebrate communities and environments at the upper and lower sites of levees in the middle reaches of paenae stream, a tributary of the naktong river,were investigated in four seasons from August 1989 to may 1990. Current velocities were significantly fast at the loer sites than the upper sites of levees. Substratum compositions were also different between these two sites. Abundances of major species of benthic macroinvertebrates occurring in four seasons were primarily dtermined by temperature. in each location of levees, however, current velocities and substratum particle sizrs were important in determining species were generally higher than upper sites of levees. Biological indices were also high at the lower sites of levees. diversity, evenness and dominance indices were positively correlated with the quantity of the middle-sized large pebbles(3∼5cm in diameter) in stream bed.

• Journal of the Korean Society of Systems Engineering
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• v.10 no.1
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• pp.73-80
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• 2014

Designing test case flows for water crossing operation of a wheeled vehicle is a new attempt for which very limited experiences exist. In this paper, a Function Flow Block Diagram(FFBD) and a Classification Tree Method(CTM) were combined to see if this method is viable to generate the test case flows at the functional analysis stage. It was found that this method can be practically used for the very complicated test case generation.

• Fisheries and Aquatic Sciences
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• v.11 no.1
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• pp.32-35
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• 2008

The Suminoe oyster, Crassostrea ariakensis, occurs in estuaries where rivers meet seawater. In Korea, it is one of the most popular fisheries resources in the Nam River and Sumjin River. However, the genetic identification of this species has been questioned, because specimens are often mis-identified as other species. To identify the species, we conducted polymerase chain reaction (PCR) amplification of the internal transcribed spacer-1 (ITS-1) region, followed by digestion with the restriction enzyme HaeIII. Restriction profiles for oysters collected from Korea, Japan, and China (north and south) were determined by comparing the PCR-restriction fragment length polymorphism (RFLP) patterns of the ITS-1 regions. Our study verified that the oysters collected from Korea were C. ariakensis based on the PCR-RFLP patterns. These results emphasize the value of molecular markers for identifying morphologically uncertain species.

• Journal of Environmental Science International
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• v.6 no.1
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• pp.33-44
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• 1997

In investigating heavy metal contents at specific areas, the method of selecting sampling points is Important A general method is, according to the law , random sampling of zigzag-form in the selected field. In this work, we studied whether the measured values obtained from a certain method of selecting sampling points is a representative of heavy metal contents in the selected field or not. The selected field for this study is located on the lower Yangsan-river: Gasan-li, Mulgum-myon, Yangsan-gun, KyoungNam, 1 km away from the mi, h stream of Nakdong river. The heavy metals investigated were Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn. The inductively coupled plasma(ICPI atomic emission spectrometer was used to measure these metals quantitatively. The number of total sampling points were 24. We compared the total mean values with the mean obtained from various methods of selecting sampling points.