A method on the reliability analysis of overtopping probability was proposed by Kweon and Suh (2003). In their calculation, the fluctuation of tidal elevation was expressed by the sinusoidal change that yields the uniform distribution of occurrence frequency. However, the realistic distribution of tidal elevation should influence on the overtopping chance. In this study, the occurrence frequency of tidal elevation obtained from the real sea is included. The tidal elevation used in this study is collected from the east coastal part of Korean peninsular. Analyzing the annual data of the tidal fluctuation measured hourly during 355 days, the distribution of occurrence frequency is formulated utilizing by the normal distribution with one peak. Among the calculation procedures of annual maximum wave height, wave height-period joint distribution, wave run-up height and occurrence frequency of tide, only the annual maximum wave height is again chosen randomly from normal distribution to consider the uncertainty. The others are treated by utilizing the distribution function or relationship itself. It is found that the inclusion of the variability of tidal elevation has great influence on the computation of the expected overtopping probability of rubble mound breakwater. The bigger standard deviation of occurrence frequency is, the lower the overtopping probability of rubble mound breakwater is.

A method on the reliability analysis of overtopping probability was proposed by Kweon and Suh (2003). In their calculation, the fluctuation of tidal elevation was expressed by the sinusoidal change that yields the uniform distribution of occurrence frequency. However, the realistic distribution of tidal elevation should influence on the overtopping chance. In this study, the occurrence frequency of tidal elevation obtained from the real sea is included. The tidal elevation used in this study is collected from the east coastal part of Korean peninsular. Analyzing the annual data of the tidal fluctuation measured hourly during 355 days, the distribution of occurrence frequency is formulated utilizing by the normal distribution with one peak. Among the calculation procedures of annual maximum wave height, wave height-period joint distribution, wave run-up height and occurrence frequency of tide, only the annual maximum wave height is again chosen randomly from normal distribution to consider the uncertainty. The others are treated by utilizing the distribution function or relationship itself. It is found that the inclusion of the variability of tidal elevation has great influence on the computation of the expected overtopping probability of rubble mound breakwater. The bigger standard deviation of occurrence frequency is, the lower the overtopping probability of rubble mound breakwater is.

The water budgets of comparing the hydrological water quantities to the demands are required to evaluate the reliabilities of the water supplies for the national plannings of water resources. The reliabilities might be reestablished according to the recent climate changes or/and the disputes of water rights between the inter-basins. In this case the computation of water budget has to be repeated overall everytime. In this study the system of water budget computation using the optimal model of MODSIM handy to make the systems was suggested for the four regions such as Han river to which this method was applied, Nakdong river, Geum river, and Yeongsan-Seomjin river region. The method of this study has the merits that it is flexible to compute the water budgets corresponding to the changes of the water supply reliabilities and it has the applicability of various water supply priorities in contrast to the past method.

The water budgets of comparing the hydrological water quantities to the demands are required to evaluate the reliabilities of the water supplies for the national plannings of water resources. The reliabilities might be reestablished according to the recent climate changes or/and the disputes of water rights between the inter-basins. In this case the computation of water budget has to be repeated overall everytime. In this study the system of water budget computation using the optimal model of MODSIM handy to make the systems was suggested for the four regions such as Han river to which this method was applied, Nakdong river, Geum river, and Yeongsan-Seomjin river region. The method of this study has the merits that it is flexible to compute the water budgets corresponding to the changes of the water supply reliabilities and it has the applicability of various water supply priorities in contrast to the past method.

Surface and subsurface flow was predicted using GIS-based distributed daily rainfall-runoff model at upstream watershed of Pyeongtaek gauging station of Anseong-cheon. By preparing model input data using GIS and RS technology, and comparing three years (2000, 2001, 2003) observed and predicted streamflows at the outlet of test watershed (Gongdo gauging station of watershed), the model was calibrated and verified. Average Nash-Sutcliffe model efficiency of three years was 0.66. As model results, maps of weekly, three months-averaged and test period-total groundwater flow were generated, respectively. By using the maps, site suitability analysis for groundwater dam and daily available groundwater yield within area were evaluated.

Surface and subsurface flow was predicted using GIS-based distributed daily rainfall-runoff model at upstream watershed of Pyeongtaek gauging station of Anseong-cheon. By preparing model input data using GIS and RS technology, and comparing three years (2000, 2001, 2003) observed and predicted streamflows at the outlet of test watershed (Gongdo gauging station of watershed), the model was calibrated and verified. Average Nash-Sutcliffe model efficiency of three years was 0.66. As model results, maps of weekly, three months-averaged and test period-total groundwater flow were generated, respectively. By using the maps, site suitability analysis for groundwater dam and daily available groundwater yield within area were evaluated.

In the present study, the theory of artificial neural networks (ANNs) was used to model runfall-runoff process. We also applied the concepts of Akaike's Information Criterion (AIC) and Bayesian Information Criterion (BIC) to determine the optimal number of parameters in constructing the ANNs model. Both criteria concurrently consider the fact that error term for an ANNs model is decreasing with the increasing hidden number, but the model is overfitted to specified data for training. After determining the input data structure and internal parameters of ANNs, we calculated the values of AIC and BIC with the number of hidden nodes from 6 to 15. The 7-nodes which minimizes AIC and BIC was selected and used for the structure of ANNs in the present study. The ANNs with 7 hidden nodes selected by the criteria in training stage were tested and validated with another runoff events. The results show that the ANNs selected in the present study generally well-performed the one-step ahead prediction of runoff in the study area, the Naju station. However, there are under-estimation and over-estimation over the runoff events with small amount of error.

In the present study, the theory of artificial neural networks (ANNs) was used to model runfall-runoff process. We also applied the concepts of Akaike's Information Criterion (AIC) and Bayesian Information Criterion (BIC) to determine the optimal number of parameters in constructing the ANNs model. Both criteria concurrently consider the fact that error termfor an ANNs model is decreasing with the increasing hidden number, but the model is overfitted to specified data for training. After determining the input data structure and internal parameters of ANNs, we calculated the values of AIC and BIC with the number of hidden nodes from 6 to 15. The 7-nodes which minimizesAIC and BIC was selected and used for the structure of ANNs in the present study. The ANNs with 7 hidden nodes selected by the criteria in training stage were tested and validated with another runoff events. The results show that the ANNs selected in the present study generally well-performed the one-step ahead prediction of runoff in the study area, the Naju station. However, there are under-estimation and over-estimation over the runoff events with small amount of error.

The exact evaluation of the available amount of groundwater development is important for the plan of water supply system. The Korea basic plan of Groundwater shows that the available amount of groundwater development was set up using the concept of groundwater recharge and the analysis of groundwater surface elevation. But we are afraid that this methodology can not reflect the water circulation concept. To improve this situation, using TOPMODEL, We calculate the long-term watershed discharge and the distribution of saturated region. the former is used for the boundary condition of aquifer flow simulation, and the later for the selection of groundwater development site. The test areas are Bocheong-river and Wi-river(IHP rivers), and the topography of the areas was analysed using GIS. the rainfall-runoff simulation is satisfactory and the sensitive analysis shows that the three parameters((m, InTo, SRmax)is the most important.

The exact evaluation of the available amount of groundwater development is important for the plan of water supply system. The Korea basic plan of Groundwater shows that the available amount of groundwater development was set up using the concept of groundwater recharge and the analysis of groundwater surface elevation. But we are afraid that this methodology can not reflect the water circulation concept. To improve this situation, using TOPMODEL, We calculate the long-term watershed discharge and the distribution of saturated region. the former is used for the boundary condition of aquifer flow simulation, and the later for the selection of groundwater development site. The test areas are Bocheong-river and Wi-river(IHP rivers), and the topography of the areas was analysed using GIS. the rainfall-runoff simulation is satisfactory and the sensitive analysis shows that the three parameters((m, lnTo, SRmax)is the most important.

The purpose of this study is to evaluate the available amount of groundwater development in the watershed aquifer. A Simulation program was made and named GFDS(Groundwater Flow and Development Simulation). GFDS can simulate the groundwater flow due to pumping in the shallow aquifer and reflect the various site condition. Samsung watershed which is near the upper site of Bocheong river (IHP project river) is selected for the program test. The area of the watershed is 107 km2 and the avilable amount of groundwater development was evaluated to be 711 million ton. The methodology of this study is the combination of surface and subsurface flow and also the combination of hydrological/hydraulic model. and we expect that this study can be useful for the projects of watershed-based groundwater development.

The purpose of this study is to evaluate the available amount of groundwater development in the watershed aquifer. A Simulation program was made and named GFDS(Groundwater Flow and Development Simulation). GFDS can simulate the groundwater flow due to pumping in the shallow aquifer and reflect the various site condition. Samsung watershed which is near the upper site of Bocheong river (IHP project river) is selected for the program test. The area of the watershed is and the avilable amount of groundwater development was evaluated to be million ton. The methodology of this study is the combination of surface and subsurface flow and also the combination of hydrological/hydraulic model and we expect that this study can be useful for the projects of watershed-based groundwater development.

The occurrence probability (OP) distributions of tide levels using harmonic constants of six tidal gauging stations in Korean coastal zone were estimated and analysed in detail. OP analysis using harmonic constants data of Incheon(Youldo), Mokpo, Yeosu, Pusan, Pohang and Sokcho was carried out and compared with the OP using hourly tidal elevation data which were served through the Internet Homepage by the National Ocean Research Institute. The tidal elevation data were divided by the AHHW (ALLW) value referenced to MSL in order to compare the OP patterns in a relative scale. The OP of the tidal elevation calculated using 38 harmonic tidal constituents relatively well agreed with those of hourly observed tidal elevation data. However, the OP results using four harmonic tidal constituents overestimate the occurrence probability at the peak points and underestimate at the tail-regions of the OP. Especially, the OP patterns of the Sokcho and Pohang tidal gauging stations on the East Sea show totally different patterns and the estimation method using four harmonic constants should be modified and application should be strictly limited on the East Sea areas. The OP patterns are considerably well generated in case of the OP generation using the additional two or three dominant tidal constituents.

The occurrence probability (OP) distributions of tide levels using harmonic constants of six tidal gauging stations in Korean coastal zone were estimated and analysed in detail. OP analysis using harmonic constants data of Incheon(Youldo), Mokpo, Yeosu, Pusan, Pohang and Sokcho was carried out and compared with the OP using hourly tidal elevation data which were served through the Internet Homepage by the National Ocean Research Institute. The tidal elevation data were divided by the AHHW (ALLW) value referenced to MSL in order to compare the OP patterns in a relative scale. The OP of the tidal elevation calculated using 38 harmonic tidal constituents relatively well agreed with those of hourly observed tidal elevation data. However, the OP results using four harmonic tidal constituents overestimate the occurrence probability at the peak points and underestimate at the tail-regions of the OP. Especially, the OP patterns of the Sokcho and Pohang tidal gauging stations on the East Sea show totally different patterns and the estimation method using four harmonic constants should be modified and application should be strictly limited on the East Sea areas. The OP patterns are considerably well generated in case of the OP generation using the additional two or three dominant tidal constituents.

In this research, parameter estimation method was suggested by investigating the effects of components on phosphorus behavior. For this purpose, anaerobic phosphorus release and aerobic uptake batch test was selected as an example experiment and simulated based on ASM2. Sensitivity analysis of phosphorus behavior on components resulted that the phosphorus release was mainly influenced by the initial poly-phosphate () in organic-rich condition and by the initial soluble COD () in organic-poor condition, while PHA () was revealed to have a high sensitivity in aerobic PHA-poor conditions and less sensitivities were detected in aerobic PHA-rich condition. Monod factor analysis supported those results. In anaerobic condition, the factor related to was high in organic-rich condition and organic matter became a limiting factor in organic-poor condition. And in aerobic condition, Monod factor was mainly dependent on the . Sensitivity and Monod factor analysis suggested the procedure to estimate model parameters. Finally, the parameters and components of sludge withdrawn from Lab-scale phosphorus removal process were estimated by suggested procedure. The simulation result with estimated parameters showed good agreements with experimental measurements.

In this research, parameter estimation method was suggested by investigating the effects of components on phosphorus behavior. For this purpose, anaerobic phosphorus release and aerobic uptake batch test was selected as an example experiment and simulated based on ASM2. Sensitivity analysis of phosphorus behavior on components resulted that the phosphorus release was mainly influenced by the initial poly-phosphate in organic-rich condition and by the initial soluble COD in organic-poor condition, while PHA was revealed to have a high sensitivity in aerobic PHA-poor conditions and less sensitivities were detected in aerobic PHA-rich condition. Monod factor analysis supported those results. In anaerobic condition, the factor related to was high in organic-rich condition and organic matter became a limiting factor in organic-poor condition. And in aerobic condition, Monod factor was mainly dependent on the . Sensitivity and Monod factor analysis suggested the procedure to estimate model parameters. Finally, the parameters and components of sludge withdrawn from Lab-scale phosphorus removal process were estimated by suggested procedure. The simulation result with estimated parameters showed good agreements with experimental measurements.

In this study, we investigated the effect of ultrasound on the dewaterability of sewage sludge. The investigation includes that CST (Capillary Suction Time) which presents dewaterability of sewage sludge, pH, temperature, and water-content with different test conditions such as ultrasonic power (P), treatment time (T), and specimen volume (L). From the results of the experiment, it could be concluded that ultrasound affects dewaterability of sewage sludge significantly. The study suggested "Influence factor of sewage sludge treated with ultrasonic ()". It is a function of not only the power of ultrasound but also the treatment time, and volume of sludge to be treated. Regression and ANN (artificial neural networks) analyses were conducted to investigate the correlation between CST and . The results of the analyses show good correlationship.

In this study, we investigated the effect of ultrasound on the dewaterability of sewage sludge. The investigation includes that CST (Capillary Suction Time) which presents dewaterability of sewage sludge, pH, temperature, and water-content with different test conditions such as ultrasonic power (P), treatment time (T), and specimen volume (L). From the results of the experiment, it could be concluded that ultrasound affects dewaterability of sewage sludge significantly. The study suggested ‘Influence factor of sewage sludge treated with ultrasonic ()’. It is a function of not only the power of ultrasound but also the treatment time, and volume of sludge to be treated. Regression and ANN (artificial neural networks) analyses were conducted to investigate the correlation between CST and . The results of the analyses show good correlationship.

Despites of efforts made for water quality conservation, water quality of the surface waters have not improved significantly due to diffuse pollution from urban and agricultural area. Especially sewer overflows impact on surface water as it show high contaminant concentrations. In this research, sewer overflows of six rainfall events at an urban watershed were monitored for their discharge rate and concentrations. For the chemical analysis, suspended solid, , nitrogen, phosphorus, Total coliform, and E. coli were measured. Pollutographs of water quality constituent showed similar trend with hydrograph. Suspended solid concentration showed high correlation with flow rate. First flush effects were clearly shown in most cases. It can be seen that rainfall intensity affects on the magnitude of first flush. Relationship between discharge rate per unit area and loading were calculated for constituents to estimate annual loading and monthly loading based on precipitation data for last five years.

Despites of efforts made for water quality conservation, water quality of the surface waters have not improved significantly due to diffuse pollution from urban and agricultural area. Especially sewer overflows impact on surface water as it show high contaminant concentrations. In this research, sewer overflows of six rainfall events at an urban watershed were monitored for their discharge rate and concentrations. For the chemical analysis, suspended solid, , , nitrogen, phosphorus, Total coliform, and E. coli were measured. Pollutographs of water quality constituent showed similar trend with hydrograph. Suspended solid concentration showed high correlation with flow rate. First flush effects were clearly shown in most cases. It can be seen that rainfall intensity affects on the magnitude of first flush. Relationship between discharge rate per unit area and loading were calculated for constituents to estimate annual loading and monthly loading based on precipitation data for last five years.

In this study, we took advantage of a sonication technology, which has been gradually applied in environment industry nowadays, drew sewage sludge dissolution optimization through sonication to improve sewage sludge disintegration much better, and maximized external carbon source production required at BNR process improvement of occurrence acidogenic fermentation. A series of bench-scale, semi-continuous acidogenic fermentation experiments, using sonicated sludge as a substrate, has been conducted to investigate the effects of sonication methods and HRT control on acidogenic fermentation. We could see the BDCOD from acidogenic fermentation after sonication considerably increase comparing with each control plot. Specifically, the increase was shown more than by 50%, 40% each. For the results of respirometry measurements used to estimate availability as substrate for microbial energy production activity, we figured out that content of COD(BDCOD) easily separable increased after sonication. Because the volatile fatty acids(VFAs) is created abundantly at anaerobic digestion step after sonication of sludge rather than before pretreatment, it could be replaced as external carbon source of BNR process, which means an enormous amount of money saved.

In this study, we took advantage of a sonication technology, which has been gradually applied in environment industry nowadays, drew sewage sludge dissolution optimization through sonication to improve sewage sludge disintegration much better, and maximized external carbon source production required at BNR process improvement of occurrence acidogenic fermentation. A series of bench-scale, semi-continuous acidogenic fermentation experiments, using sonicated sludge as a substrate, has been conducted to investigate the effects of sonication methods and HRT control on acidogenic fermentation. We could see the BDCOD from acidogenic fermentation after sonication considerably increase comparing with each control plot. Specifically, the increase was shown more than by 50%, 40% each. For the results of respirometry measurements used to estimate availability as substrate for microbial energy production activity, we figured out that content of COD(BDCOD) easily separable increased after sonication. Because the volatile fatty acids(VFAs) is created abundantly at anaerobic digestion step after sonication of sludge rather than before pretreatment, it could be replaced as external carbon source of BNR process, which means an enormous amount of money saved.