• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.3
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• pp.81-90
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• 2016

It is significant to redevelop the deterioration reservoir through raising for countermeasure to climate change and Earthquake improvement of reservoir. This study aims to investigate the behavior of deterioration reservoir with poor-fabricated core subjected to raising water level and earthquake using numerical analysis. From the analysis results, water level raising and earthquakes induce crack and subsidences at the crown and the front side of deterioration reservoir. For the reinforcement of the deterioration reservoir is required appropriate measures method and raised method suitable, drainage and slope protection method judged to be necessary.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.3
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• pp.91-100
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• 2016

Recently, lots of damages have been lost because large magnitude earthquakes were occurred in the world. It has been increased the number of earthquakes in Korea. It needs improvement required for the repair of deteriorated reservoirs, reinforcement and raised reservoir coping with climate change and earthquake. This study aims to investigate the seismic behavior of deterioration reservoir levee using dynamic centrifugal model test. Therefore, two case tests in centrifugal field of 60 g, the result has provided the influence on the acceleration response, displacement, settlement and the pore water pressure of the reservoir with earthquakes. From the results larger displacement and acceleration response at the front side of reservoir embankment with poor-fabricated core in seismic condition may degrade overall stability. Reasonable reinforcement method of the raised reservoir embankment is required for ensuring long-term stability on earthquake.

• Earthquakes and Structures
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• v.26 no.1
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• pp.59-75
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• 2024

This paper presents a dam-reservoir interaction model that includes, water compressibility, sloshing of surface water, and radiation damping at the far-end reservoir, to investigate the influence of concrete deterioration on seismic behavior along with seismic performance of gravity dams. Investigations on seismic performance of the dam body have been conducted using the linear time-history responses obtained under six real and 0.3 g normalized earthquake records with time durations from 10 sec to 80 sec. The deterioration of concrete is assumed to develop due to mechanical and chemical actions over the dam lifespan. Several computer programs have been developed in FORTRAN 90 and MATLAB programming languages to analyze the coupled problem considering two-dimensional (2D) plane-strain condition. According to the results obtained from this study, the dam structure shows critical responses at the later ages (75 years) that could cause disastrous consequences; the critical effects of some earthquake loads such as Chi-Chi with 36.5% damage and Loma with 56.2% damage at the later ages of the selected dam body cannot be negligible; and therefore, the deterioration of concrete along with its effects on the dam response should be considered in analysis and design.

• Journal of Korean Society on Water Environment
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• v.30 no.4
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• pp.429-440
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• 2014

This study was conducted to investigate the main cause of water quality deterioration during the spring season in the transition zone between the South Han River and the river-reservoir Paldang. A water quality model modified from QUAL2E (U.S.EPA) was used, and the model showed that eutrophication and algal production in the low flow season affected about 60% of the organic pollution at the downstream of the South Han River. This result means that phosphorus control is prior to external organic material management to ameliorate the deterioration of water quality in the water body.

• Magazine of the Korean Society of Agricultural Engineers
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• v.65 no.3
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• pp.32-39
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• 2023

• The Journal of the Korea Contents Association
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• v.11 no.9
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• pp.246-253
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• 2011

Several problems occurred due to the use of the wrong water cycle system in the watershed. This was caused by a dry stream in the lower parts of the tributaries and the deterioration in value of usage by water pollution in accordance with water storage. This was maintained for a long period of time in the reservoir which secured the agricultural water. As a result of the operational status in the agricultural reservoirs focused on Chungcheongnam-do and Daejeon metropolitan city, a dry stream appeared because hydraulic retention time(HRT) in the majority of reservoirs was maintained for 8 months of the year. The water quality in the agricultural reservoir was fairly related to the water cycle system due to rainfall and input of pollutants from the population and livestock in the watershed. Consequently, the storage water volume and the time period of the water in the reservoir should be controlled by the reduction of the pollution load in the water and the prevention of a dry stream. Also, the water cycle system in the watershed should be improved by maintaining a short HRT of the reservoir.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.5
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• pp.73-84
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• 2020

In this study, we compared and analyzed the static and dynamic analysis method for agricultural reservoirs. In addition, we assumed the aging of reservoir as the deterioration of the internal friction angle and cohesion. The internal friction angle and cohesion were applied by dividing into 4 case for each reservoir. As a result of comparing the stability of the reservoir embankment, it was found that the dynamic stability analysis method showed a greater risk than the static stability analysis method when dynamic loads such as earthquakes were applied. Therefore, when detailed review such as liquefaction is required, it is considered that the dynamic stability analysis method should be applied first. If a study on the change in material properties due to the aging of the reservoir is conducted, the stability analysis of the reservoir due to the aging of the reservoir can be performed more accurately. In addition, if a study comparing the results of dynamic stability analysis and static stability analysis for earthquakes with various characteristics for more reservoirs is conducted, detailed criteria for the case where dynamic stability analysis should be considered can be presented.

• Journal of Environmental Science International
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• v.9 no.2
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• pp.115-123
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• 2000

The dynamics of water quality and phytoplankton population had examined by monthly sampling from the upper to the lower part of watergate in an artificial Shihwa Reservoir in which situated near newly cities and incustrial complex on the west coast of Korea from January 1997 to December 1998. Among environmental factors, yearly average concentration of chl-a, TN and TP seemed to eutrophic or hypertrophic conditions that ranged 146.4~245.8 $\mu\textrm{g}$/$\ell$, 1.6~2.7 mg N/$\ell$, 258~448 $\mu\textrm{g}$ P/$\ell$, 26.9~80.7 $\mu\textrm{g}$/$\ell$, 1.0~2.4 mgN/$\ell$ and 74~239 $\mu\textrm{g}$P/$\ell$ respectively. Water quality was extremely deteriorated to consistently accumulation into inner reservoir by load of pollutants from autochthonous and allochthonous until early July 1997 after embankment. Water pollution of Shihwa Reservoir was remarkble on the biological condition with largely persistent bloom of phytoplankton and increase rate of standing crops was 2.4/yr. The development trend of phytoplankton in water ecosystem were closely related to increse and decrease of physico-chemical factors and those scale seemed to control by nutrient contents. Inflow of seawater into reservoir to object of repair of water quality. As to see dominant species, composition of those composed to mostly freshwater algae before inflow of seawater such as Selenastrum capricornutum of green algae, cyclotella atomus, C. meneghiniana of diatom and Microcystis spp. of blue-green algae and the other hand brackish algae were dominated after inflow of seawater such as Chaetoceros dicipiens, Skeletonema costatum of diatom, Dinophysis acuminata, Gymnodinium mikimotoi, G. sanguineum, Gyrodinium spirale, Prorocentrum minmum of dinoflagellate and Eutreptiella gymnastica of euglenoid. Moreover, small flagellates including Chroomonas spp. of cryptomonad were abundant throughout the year. The cause of water deterioration during fill of the freshwater were complexly supported with extra and intra parameters. The variation pattern of phytoplankton were related to water temperature and salinity by inflow of seawater based to plentiful nutrients. The dynamics of phytoplankton were assessed to ecosystem that clearly condition of dominant by unique or a few angel species seasonally.

• Journal of Korean Society on Water Environment
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• v.38 no.6
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• pp.275-281
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• 2022

To maintain water quality after water treatment, monitoring whether the quality of treated tap water quality changes is essential. However, current investigations are insufficient to prevent secondary contamination in drinking water supply systems. This study investigated Gyeonggi's e apartment where a red water problem occurred and monitored the water quality and corrosiveness of the overall water supply system to the apartment from June 2021 to April 2022. In a comparison of drinking water quality after water treatment and the influent of the reservoir, turbidity and heavy metal concentrations were increased and residual chlorine was decreased due to increases in temperature. Correlation analysis and principal component analysis (PCA) indicated that a low level of residual chlorine may cause the abscission of Mn²⁺ and Fe²⁺ through microorganism activation, which also causes a high level of turbidity. The corrosion index (LI) in the influent of the reservoir tank was increased due to Ca²⁺ and temperature. These results indicate that the corrosiveness of drinking water and the deterioration of drinking water quality were mainly increased between the drinking water treatment plant and the reservoir tank's influent. The findings provide clear evidence that it is essential to manage water supply systems and reservoir tanks to prevent the secondary contamination of drinking water.

• Water Engineering Research
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• v.3 no.2
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• pp.143-153
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• 2002

As the natural flows in rivers dramatically decrease during drought season in Korea, a deterioration of river water quality is accelerated. Thus, consideration of downstream water quality responding to changes in reservoir release is essential for an integrated watershed management with regards to water quantity and quality. In this study, water quality models based on artificial neural networks (ANNs) method were developed using historical downstream water quality (rm $\NH_3$-N) data obtained from a water treatment plant in Geum river and reservoir release data from Daechung dam. A nonlinear multiple regression model was developed and compared with the ANN models. In the models, the rm NH$_3$-N concentration for next time step is dependent on dam outflow, river water quality data such as pH, alkalinity, temperature, and rm $\NH_3$-N of previous time step. The model parameters were estimated using monthly data from Jan. 1993 to Dec. 1998, then another set of monthly data between Jan. 1999 and Dec. 2000 were used for verification. The predictive performance of the models was evaluated by comparing the statistical characteristics of predicted data with those of observed data. According to the results, the ANN models showed a better performance than the regression model in the applied cases.