• Journal of Korean Society on Water Environment
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• v.21 no.4
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• pp.360-367
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• 2005

We have performed to analyze the trophic state resulting of Lake Yongdam as a result of water quality and nutrient concentration. Lake Yongdam is artifitial multi-purpose Dam resulting from the floods of 2001. The water quality of Lake Yongdam may affect the status of the Geum river basin including the Daecheong reservoir. It is necessary to understand the trophic state to assess water quality until stability after flooding. Water quality was surveyed using depth and hydraulic condition analysis. Further density flow was estimated for stratification and trophic state of Lake Yongdam by chlorophyll ${\alpha}$ concentration (2001~2004). And Environmental factors on chlorophyll ${\alpha}$ concentration were analyzed statistically. Trophic state was evaluated as the oligotrophic state at the main stream of the reservoir and eutrophic state at the upper stream in 2001, but evaluated as eutrophic state in 2002 and 2003 by TSI of Aizaki. From the results of multiple regression analysis using stepwise method, chlorophyll ${\alpha}$ concentration was shown to be very significant when nutrient concentration is high upon initial filling of the Dam. Chlorophyll ${\alpha}$ concentration varied according to sample site, season and year. Concentration were high in the upper stream of Lake Yongdam 4, algae bloom in these watershed were affected by location and high nutrient levels in the summer season which have in turn increased phytoplankton bloom into the reservoir.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.745-746
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• 2005

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.235-236
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• 2005

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.691-692
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• 2005

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.138-140
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• 2005

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.785-786
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• 2005

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.78-83
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• 2012

Man-made reservoirs over 95% in Korea are shallower than 10 meters in depth, which is apt to cause eutrophication. This study has characterized long-term trends in water quality factors for the selected six reservoir points in the Kum River watersheds, and then estimated the seasonal trophic state index for each reservoir. The reservoir trophic state was evaluated at four trophic levels using the Korean trophic state index, TSIKO. It is observed from seasonal results for six reservoirs that the highest value of the trophic state index is estimated in summer while the trophic state index value is low in spring and winter seasons. Especially, the Boryeong Lake has a relatively lower trophic state index since this reservoir has been managed properly for water withdrawal and irrigation. It is expected that the seasonal trophic state index resulted from this study can contribute toward long-term water quality improvement plans for reservoirs.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.146-153
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• 2004

The goals of this study are to investigate the feasibility of the reference state approach in determining the generalized soil-water characteristic curve that is essential for characterization of unsaturated soil behavior. The soil-water characteristic curves are obtained from a number of specimens of fine-grained residual soils compacted with different void ratios. Based on the experimental test results, the feasibility of using the liquid limit state as the reference state for predicting the soil-water characteristic curve are verified. Finally, through the regression analysis of experimental data using the equation of Fredlund and Xing (1994), a reliable method is proposed to predict the generalized soil-water characteristic curve of fine-grained residual soils using the liquid limit state as the reference.

• Geomechanics and Engineering
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• v.38 no.3
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• pp.215-229
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• 2024

Because of the various patterns of deep-water inrush and complicated mechanisms, accurately predicting mine water inflows is always a difficult problem for coal mine geologists. In study presented in this paper, the water inrush channels were divided into four basic water diversion structures: aquifer, rock fracture zone, fracture zone and goaf. The fluid flow characteristics in each water-conducting structure were investigated by laboratory tests, and multistructure and multisystem coupling flow analysis models of different water-conducting structures were established to describe the entire water inrush process. Based on the research of the water inrush flow paths, the analysis model of different water inrush space structures was established and applied to the prediction of mine water inrush inflow. The results prove that the conduction sequence of different water-conducting structures and the changing rule of permeability caused by stress changes before and after the peak have important influences on the characteristics of mine water-gushing. Influenced by the differences in geological structure and combined with rock mass RQD and fault conductivity characteristics and other mine exploration data, the prediction of mine water inflow can be realized accurately. Taking the water transmitting path in the multistructure as the research object of water inrush, breaking through the limitation of traditional stratigraphic structure division, the prediction of water inflow and the estimation of potentially flooded area was realized, and water bursting intensity was predicted. It is of great significance in making reasonable emergency plans.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1888-1893
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• 1991

Systematic design of a controller for a water temperature system was considered, with the intention of devising an accurate control experiment. The results of an experiment using a water temperature system based on the pole placement regulator showed water temperature oscillation and steady state error. This paper proposed a. method for eliminating both the oscillation and the steady state error. The oscillation was eliminated by a drive delay compensation technique, in which a future state value of the system was predicted through a real time computer simulation. The steady state error was eliminated by an steady state error correction technique, in which an actual steady state heatrate in the system model was replaced by an imaginary heatrate. By combining these two techniques, we obtained an experimental result for water temperature control of 0.01 (.deg. C) accuracy. Furthermore, the proposed method was evaluated relatively by comparing the experimental results using several other methods and proved to be the most accurate and convenient control method for the delay system.