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An oscillatory S-curve causes unexpected fluctuations in a unit hydrograph (UH) of desired duration or an instantaneous UH (IUH) that may affect the constraints for hydrologic stability. On the other hand, the Savitzky–Golay smoothing and differentiation filter (SG filter) is a digital filter known to smooth data without distorting the signal tendency. The present study proposes a method based on the SG filter to cope with oscillatory S-curves. Compared to previous conventional methods, the application of the SG filter to an S-curve was shown to drastically reduce the oscillation problems on the UH and IUH. In this method, the SG filter parameters are selected to give the minimum influence on smoothing and differentiation. Based on runoff reproduction results and performance criteria, it appears that the SG filter performed both smoothing and differentiation without the remarkable variation of hydrograph properties such as peak or time-to peak. The IUH, UH, and S-curve were estimated using storm data from two watersheds. The reproduced runoffs showed high levels of model performance criteria. In addition, the analyses of two other watersheds revealed that small watershed areas may experience scale problems. The proposed method is believed to be valuable when error-prone data are involved in analyzing the linear rainfall–runoff relationship.
Kee-Won Seong; Jang Sung. Derivation of S-Curve from Oscillatory Hydrograph Using Digital Filter. Water 2021, 13, 1456 .
AMA StyleKee-Won Seong, Jang Sung. Derivation of S-Curve from Oscillatory Hydrograph Using Digital Filter. Water. 2021; 13 (11):1456.
Chicago/Turabian StyleKee-Won Seong; Jang Sung. 2021. "Derivation of S-Curve from Oscillatory Hydrograph Using Digital Filter." Water 13, no. 11: 1456.
The relationships between a variety of hydro-meteorological variables and irrigation water use rates (WUR) were investigated in this study. Standardized Precipitation Index (SPI), Potential Evapotranspiration (PET), and Normalized Difference Vegetation Index (NDVI) were explored to identify the relationship with the WUR. The Yeongsan river basin, the agricultural land of which is mostly occupied by well-irrigated paddy, was used for the pilot study. Four different temporal scales of SPI-3, 6, 9, and 12 were tested, and PET was calculated using the Thornthwaite method. To calculate NDVI, the surface spectral reflectance data, which was acquired by Moderate Resolution Imaging Spectroradiometer (MODIS) equipped on the Terra satellite, were used. As a result, there was a statistically significant relationship between SPI9 and the WUR during drought periods in which negative values of SPI9 were obtained. The WUR was strongly correlated with both PET and NDVI. Compared with SPI, the variability of WUR in this study area was more sensitively affected by PET and NDVI, which can cause a potential lack of agricultural water supply. The finding of this study implies that SPI9, PET, and NDVI are the critical factors for predicting water withdrawal during drought conditions so that they can be used for irrigational water use management. Although a part of the findings of this study has been discussed by a few previous studies, this study is novel in that it quantifies the relationship between these factors using actual field observations of streamflow withdrawal for irrigation.
Jang Sung; Donghae Baek; Young Ryu; Seung Seo; Kee-Won Seong. Effects of Hydro-Meteorological Factors on Streamflow Withdrawal for Irrigation in Yeongsan River Basin. Sustainability 2021, 13, 4969 .
AMA StyleJang Sung, Donghae Baek, Young Ryu, Seung Seo, Kee-Won Seong. Effects of Hydro-Meteorological Factors on Streamflow Withdrawal for Irrigation in Yeongsan River Basin. Sustainability. 2021; 13 (9):4969.
Chicago/Turabian StyleJang Sung; Donghae Baek; Young Ryu; Seung Seo; Kee-Won Seong. 2021. "Effects of Hydro-Meteorological Factors on Streamflow Withdrawal for Irrigation in Yeongsan River Basin." Sustainability 13, no. 9: 4969.
A general form of formula is presented for the rainfall Intensity–Duration–Frequency (IDF) relationship. This formula is derived from the nearly normal probability distribution function of transformed intensities. In order to transform the raw intensities, a correcting non-constant spread technique, the Kruskal–Wallis statistic, and the Box–Cox transformation are adopted. These transformations enable to express a simpler model for the IDF formula that agrees well with traditional IDF relationships. Since the proposed method allows the estimation of any percentile value of intensities with a single equation, the intensity percentile at arbitrary duration can be generated easily. The validity of the formula derived by means of the proposed method is assessed using data from major weather stations in Korea. The results show that the percentile intensities produced using the proposed method are in good agreement with those of traditional frequency analysis. Copyright © 2013 John Wiley & Sons, Ltd.
Kee-Won Seong. Deriving a practical form of IDF formula using transformed rainfall intensities. Hydrological Processes 2013, 28, 2881 -2896.
AMA StyleKee-Won Seong. Deriving a practical form of IDF formula using transformed rainfall intensities. Hydrological Processes. 2013; 28 (6):2881-2896.
Chicago/Turabian StyleKee-Won Seong. 2013. "Deriving a practical form of IDF formula using transformed rainfall intensities." Hydrological Processes 28, no. 6: 2881-2896.
The values of the parameters of the Clark instantaneous unit hydrograph (IUH) are often relying on the subjective decision of the researcher, which leads to large variations of their values. Therefore, an objective method minimizing the subjective judgement in the IUH modelling procedure while providing a reduced range of acceptable values is proposed. The proposed method uses a basin average IUH to mitigate the robustness problem of the Clark IUH parameters. Using linear system theory, the z‐transform is applied to the average IUH and then the IUH polynomial is factored into the recession and time‐area curve (TAC) components based on a convolution relation between the Clark IUH parameters. During this calculation, the root selection method was adopted to verify the storage coefficient R from the recession component and a linear programming technique was applied for determining the TAC for the basin of interest. The Wi River basin was used to test the applicability of the proposed method. The results showed that the components of a single reservoir and the TAC for Clark IUH were separated effectively, and acceptable values for the parameters were obtained. Copyright © 2011 John Wiley & Sons, Ltd.
Kee-Won Seong; Yong-Hak Lee. A practical estimation of Clark IUH parameters using root selection and linear programming. Hydrological Processes 2011, 25, 3676 -3687.
AMA StyleKee-Won Seong, Yong-Hak Lee. A practical estimation of Clark IUH parameters using root selection and linear programming. Hydrological Processes. 2011; 25 (23):3676-3687.
Chicago/Turabian StyleKee-Won Seong; Yong-Hak Lee. 2011. "A practical estimation of Clark IUH parameters using root selection and linear programming." Hydrological Processes 25, no. 23: 3676-3687.
When a prestressed double-T beam is subjected to torsion, a pair of prestressing tendons resists torsional rotation because of the restoring action of the displaced prestressing tendons. A comprehensive formulation to account for the torsional restoring action of double-T beams is presented, based on Vlasov’s hypothesis of considering warping displacement in an open-section. The deformation energies of prestressing tendons and reinforcing bars are calculated based on the deformed geometry to obtain the total potential energy. A two-noded beam element with seven degrees of freedom per node approximates an axial displacement, two translations, two flexural, and one torsional rotations, and a warping displacement to derive the finite-element equilibrium equations by minimizing the potential energy function. The role of prestressing forces of the tendons on the torsional resistance and the limitations of the traditional transformed section approach are addressed when it is applied to torsional problems. As a numerical example, an existing three-span continuous double-T beam is analyzed, and the bimoment and angle of twist are compared to those calculated using conventional three-dimensional finite-element analysis and the analytical solution of governing differential equations.
Yong-Hak Lee; Won-Jin Sung; Kee-Won Seong. Torsional Stiffness of Prestressing Tendons in Double-T Beams. Journal of Engineering Mechanics 2011, 137, 61 -72.
AMA StyleYong-Hak Lee, Won-Jin Sung, Kee-Won Seong. Torsional Stiffness of Prestressing Tendons in Double-T Beams. Journal of Engineering Mechanics. 2011; 137 (1):61-72.
Chicago/Turabian StyleYong-Hak Lee; Won-Jin Sung; Kee-Won Seong. 2011. "Torsional Stiffness of Prestressing Tendons in Double-T Beams." Journal of Engineering Mechanics 137, no. 1: 61-72.
Kee-Won Seong; James E. Ball; Yong-Hak Lee. Application of a regionalized Clark IUH model with limited hydrologic data availability. Hydrological Processes 2008, 22, 3651 -3660.
AMA StyleKee-Won Seong, James E. Ball, Yong-Hak Lee. Application of a regionalized Clark IUH model with limited hydrologic data availability. Hydrological Processes. 2008; 22 (18):3651-3660.
Chicago/Turabian StyleKee-Won Seong; James E. Ball; Yong-Hak Lee. 2008. "Application of a regionalized Clark IUH model with limited hydrologic data availability." Hydrological Processes 22, no. 18: 3651-3660.
A procedure is presented for developing a rainfall intensity–duration–frequency (IDF) relationship that is consistent with bivariate normal distribution modeling. The Box–Cox transformation was used to derive the relation and two methods of determining the parameters of this transformation were evaluated. To assess the uncertainty of the parameters, a confidence interval was constructed and verified with the non-parametric bootstrap method. Additionally, the effect of sample size on the bivariate normality assumption was examined. Case studies, based on data from significant gauge stations in Korea, were performed. The result shows that the use of the bivariate normal model as an IDF relationship is particularly recommended when the available data size is small.
Kee-Won Seong; Yong-Hak Lee. Derivation and assessment of a bivariate IDF relationship using paired rainfall intensity–duration data. Stochastic Environmental Research and Risk Assessment 2007, 23, 1 -7.
AMA StyleKee-Won Seong, Yong-Hak Lee. Derivation and assessment of a bivariate IDF relationship using paired rainfall intensity–duration data. Stochastic Environmental Research and Risk Assessment. 2007; 23 (1):1-7.
Chicago/Turabian StyleKee-Won Seong; Yong-Hak Lee. 2007. "Derivation and assessment of a bivariate IDF relationship using paired rainfall intensity–duration data." Stochastic Environmental Research and Risk Assessment 23, no. 1: 1-7.
A simple simulation type approach and a statistical method are proposed for determining the confidence interval of the T‐year frequency rainfall percentiles (or precipitation extremes) for generalized extreme value (GEV) distributions. The former method is based on the Monte Carlo testing procedure. To generate realizations, the covariance structure of the three parameters of GEV is investigated using an observed information matrix of the likelihood function. For distributions with realistic parameters, the correlation between the location and the scale parameters is practically constant when the shape parameter varies around values close to its optimal value. The latter method is based on likelihood ratio statistics. In the case where the joint confidence surface for shape parameters and estimates is plotted with lines of best estimates, the region where the estimated best percentile value can be chosen as a possible estimate is part of the joint confidence surface. The projection of this bounded region on axis of percentile is defined as the effective confidence interval in this research. The use of this effective interval as the confidence interval of the percentile of T‐year frequency rainfall is particularly recommended because it is stable for T and it reflects variations in all three parameters of GEV appropriately.
Kee-Won Seong; Yong-Hak Lee. TWO PRACTICAL APPROACHES FOR DETERMINING THE CONFIDENCE INTERVAL OF RAINFALL DEPTH PERCENTILES. JAWRA Journal of the American Water Resources Association 2003, 39, 369 -380.
AMA StyleKee-Won Seong, Yong-Hak Lee. TWO PRACTICAL APPROACHES FOR DETERMINING THE CONFIDENCE INTERVAL OF RAINFALL DEPTH PERCENTILES. JAWRA Journal of the American Water Resources Association. 2003; 39 (2):369-380.
Chicago/Turabian StyleKee-Won Seong; Yong-Hak Lee. 2003. "TWO PRACTICAL APPROACHES FOR DETERMINING THE CONFIDENCE INTERVAL OF RAINFALL DEPTH PERCENTILES." JAWRA Journal of the American Water Resources Association 39, no. 2: 369-380.