• Journal of Environmental Science International
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• v.25 no.9
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• pp.1253-1267
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• 2016

After large-scale flooding damage occurred along the Imjin river in 1996, 1998, and 1999, the Hantan river flood control dam was planned, and it has since been under construction. Unlike existing dams in Korea, the Hantan river flood control dam will remain fully open except during high floods, when the dam will store flood water temporarily to reduce flood peaks and flood water volume downstream. During past flooding seasons, floating debris has caused difficulties in the management of large-scale dams. Most of the existing multipurpose dams in Korea have installed nets to collect floating debris based on many years of experience with and data about inflow and distribution of floating debris in the dams. For the Hantan river flood control dam, however, collection of data about inflow and distribution of floating debris is not possible as the dam is located near the border area between North and South Korea. In order to devise a preliminary plan to collect floating debris in the Hantan river flood control dam, an EFDC hydrodynamic model was used to analyze the behavior of floating debris during high floods. The Lagrangian particle tracking method was utilized to simulate the behavior of floating debris in the dam. Based on the analysis of paths and final destinations of the particles, seven collection points were selected where it seemed to be effective to collect floating debris, as debris is likely to accumulate there in high density.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.287-294
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• 2019

This study investigated longitudinal changes in riverbed materials properties and temporal alteration of river channel geomorphology in the Geum River basin, where two multipurpose dams(Yongdam Dam and Daecheong Dam) were built in upstream area. We carried out grain size distribution analyses and measured soil organic matter contents of riverbed materials taken at the upper and lower sites of the two large dams. We also estimated the channel width, bar area and vegetation encroachment using the oldest map and aerial photographs taken before and after the construction of the dams. The results can contribute to increasing understandings of dam induced habitat alteration in river ecosystem.

• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.4
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• pp.161-170
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• 2014

Newmark-type deformation analysis has rarely been done in Korea due to the popularity of simple pseudo-static limit equilibrium analysis and detailed time-history FE/FD dynamic analysis. However, the Korean seismic dam design code updated in 2011 prescribes Newmark-type deformation analysis as a major dynamic analysis method for the seismic evaluation of fill dams. In addition, a design PGA for dynamic analysis is significantly increased in the code. This paper aims to study the seismic evaluation of four existing large fill dams through advanced FEM/Newmark-type deformation analyses for the artificial earthquake time histories with the design PGA of 0.22g. Dynamic soil properties obtained from in-situ geo-physical surveys are applied as input parameters. For the FEM/Newmark analyses, sensitivity analyses are performed to study the effects of input PGA and $G_{max}$ of shell zone on the Newmark deformation. As a result, in terms of deformation, four fill dams are proved to be reasonably safe under the PGA of 0.22g with yield coefficients of 0.136 to 0.187, which are highly resistant for extreme events. Sensitivity analysis as a function of PGA shows that $PGA_{30cm}$ (a limiting PGA to cause the 30 cm of Newmark permanent displacement on the critical slip surface) is a good indicator for seismic safety check. CFRD shows a higher seismic resistance than ECRD. Another sensitivity analysis shows that $G_{max}$ per depth does not significantly affect the site response characteristics, however lower $G_{max}$ profile causes larger Newmark deformation. Through this study, it is proved that the amplification of ground motion within the sliding mass and the location of critical slip surface are the dominant factors governing permanent displacements.

• Journal of Korea Water Resources Association
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• v.47 no.5
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• pp.411-420
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• 2014

The water resources sustainability is becoming an important issue in consideration of hydrologic uncertainty by global warming and climate change. This study is to assess the water supply performance for the major multipurpose dams using sustainability index. Parameters, mostly utilized in water resources system assessment, are selected in respect of applicability and flexibility, and those parameters are used as a variable of the composite index. In practice, the composite index including reliability, resiliency, vulnerability and maximum deficit are applied to 15 multipurpose dams and 4 major basins. And to conclude, Daechungdam in the Geum river basin and Imhadam, Hapchondam and Namgangdam in the Nakdong river basin show low sustainability comparing with other dams. The Nakdong river basin needs to develop alternatives to improve water supply stability because it indicates the most poor sustainability level.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1919-1924
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• 2014

Recently, due to the climate change, the frequency and intensity of extreme rainfall events have been continuously increased in regions of South Korea. As a consequence, safety issues have been raised especially in the hydrologic safety of old dams designed and constructed by the old standards. In general, for improving hydrologic safety of existing dams, two options are considered: 1) raising dam crest; and 2) constructing or expanding an emergency spillway. In this process, the main criteria of alternative selection are overtopping possibility and cost efficiency of each alternative. This approach is easy to implement but it is subject to major limitation for the proper evaluation of alternatives, overlooking downstream flood damages by any controlled flow of water that is intentionally released from dams to eliminate the possibility of overtopping. Therefore, this study suggests a framework for evaluating the dam safety strengthening alternatives in terms of a comprehensive flood control by applying the concept of resilience. The case study shows that the resilience-based evaluation framework which considering downstream flood damages is effective in the selection of dam safety strengthening alternatives.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1815-1829
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• 2014

Recently frequent collapse of old fill dams has taken place, which increases social awareness in the safety of the infrastructure. Fill dams in Korea has been incautiously regarded as safe once the fill dam is considered to have a full capacity to retain a conservative design flood determined by government authorities. However, developed foreign countries has been managing their fill dams by introducing systematic risk assessment techniques over a long period of time. In this study, the system response probabilities of the deteriorated old fill dams in Korea were systematically evaluated and analyzed by using the internal erosion toolbox based on the event tree analysis technique. The probability of the existence of flaw and the magnitude of the hydraulic gradient through a potential crack can significantly influence the geotechnical system response probability. The results of this study show that the probability of the existence of flaw and the magnitude of the hydraulic gradient through a potential crack can significantly influence the geotechnical system response probability and the risk of the deteriorated fill dam can be quantitatively assessed.

• Journal of Environmental Health Sciences
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• v.30 no.2
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• pp.71-78
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• 2004

This study was performed to evaluate developmental and estrogenic activity of bisphenol A (BPA) and butyl benzyl phthalate (BBP) to the second generation of Sprague-Dawley rats ingested during gestational or lactational periods. Rats were given BPA 20$\mu\textrm{g}$/kg BBP 100mg/kg of pregnancy or lactation periods. Maternal body weight and neonatal body weight were recorded. The rats were sacrificed on day 21 after birth. Reproductive organs of dam and neonate were utilized for receptor binding assay. The plasma concentrations of BPA and MBep, one of the major metabolites of BBP were analyzed with HPLC. The co-administration of BPA and BBP induced slow weight gain compared with single administration in dams. Also, such mixture induced low neonatal body weights in next generation. The dams treated with BPA and BBP during lactational periods showed significant organ weight changes in liver and spleen. The dams exposed during lactational periods showed significant organ weight changes not only in liver and spleen but also in kidney, uterus and ovary. The F1 female rats exposed during lactation periods showed significant organ weight changes in liver, spleen, ovary. The F1 male rats showed significant organ weight changes in liver, kidney, epididymis, vesicular glands, prostate. However, no clear synergistic effects of BPA and BBP were noted. There was no significantly different ER$\alpha$ expression pattern between control and treated groups. However, ER$\alpha$ expression were increased in F1 male testis and female uterus. PI male showed distinct ER$\alpha$ expression, especially in the group of lactational combined exposure. Synergistic ER$\alpha$ expression was found by combined treatment of BPA and BBP. We could not find any evidences of synergistic effects on BPA and/or BBP combined administration on dams and their fetuses, except in ER$\alpha$ expression of F1 male.

• Journal of the Korean Geotechnical Society
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• v.32 no.11
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• pp.51-60
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• 2016

In determining a shear wave velocity (Vs) profile model based on field tests for dams, the uncertainties always exist. These uncertainties are caused by spatial variations of material properties in each dam and between dams and should be considered in determining Vs profile model for dams. In this paper, these uncertainties are evaluated and Vs profile model for core zone of fill dam in Korea is proposed using the shear wave velocity profiles determined in seven fill dams. The proposed Vs profile model is compared with Kim's model and Sawada-Takahashi model widely used for evaluation of Vs profile of core zone of fill dam.

• Journal of Korea Water Resources Association
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• v.43 no.4
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• pp.325-336
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• 2010

This study presents the alteration of flow regime by effects of dams and water use in the Geum River Basin. The surface water use rate and the Impounded Runoff (IR) index were examined to assess the pressure indicators of the flow alteration. We applied the flow duration curve, flow regime coefficient, flood and low-flow frequency analysis as well as Range of Variability Approach (RVA) to investigate the quantitative changes in natural flow regimes. The results indicate that the high flow decreased and low flow increased respectively compared to the natural flow regimes at eight gauging stations. The Geum river is regulated by 139 dams and reservoirs storing 24% of the annual mean discharge and has high surface water use rate of 36%. These indicators are main pressure factors to alter flow regimes.

• Journal of Nutrition and Health
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• v.32 no.8
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• pp.855-863
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• 1999

This study was performed to investigate the effect of dietary protein level throughout gestation and lactation on milk composition and on postnatal growth in infants, using rats as an animal model. Female Sprague-Dawley rats were provided with either high(25% ISP(Isolated Soy Protein)diet) or low protein diet(10% ISP diet) throughout gestation and lactation. Milk samples were taken for analysis from the lactating rats at days of 7, 14, 21, of lactation. Dams and some pups were killed after 4 weeks from parturtion (Experiment 1). Pups from dams of each diet groups were randomly selected and reared with 25% or 10% ISP diet for 4 more weeks (Experiment 2). In experiment 1, maternal protein intake and body weight gain throughout gestation and lactation was higher in 25% ISP group. Serum protein, Ca, Fe, Zn, K concentrations were significantly higher in 25% ISP group. There was no difference in birth weight between two groups, however the mean body weight at 4 weeks postpartum were significantly higher in 25% ISP group. Serum profiles of pups at weaning were similar to that of dams. Milk compositions were changed during lactation processes and were affected by dietary protein level. Lactose and Ca, Cu, Fe concentrations in milk were higher in 25% ISP group, whereas, lipid, triglyceride were higher in 10% ISP group. In experiment 2, food intake was higher in milk were higher in 25% ISP group but was unaffected by pup's dietary protein level after weaning. The weights of liver and kidney were affected by maternal protein intake. The weight of intestine was affected by pup's dietary protein level after weaning. The weight of femur and scapula were affected by maternal protein intake. There were no differences between four groups in serum profiles. Therefore, as mentioned above, it seemed that the effect of maternal protein malnutrition to fetus was able to be overcome to some extent by high protein diet intake after weaning. In conclusion, 1) Dietary protein level throughout gestation and lactation affected both nutritional status of dams and pups and milk composition: 25% ISP groups supported better nutritional status than 10% ISP group 2) It seemed that effect of dietary protein level after weaning on pups was able to be overcome the influence of maternal diet in fetus to some extent.