1. A Consistent Nonlinear Mild-Slope Equation Model

The model is an enhancement over previous work in that a closer correspondence between the scaling of nonlinearity and horizontal variation of bathymetry is made relative to earlier models. This results in additional terms in the nonlinear summation terms of the model, as amplitude gradient terms are required in order to formulate a consistent model. From the resulting elliptic model, a parabolic approximation is developed in order to efficiently model the equations. Comparisons between the present model, previously-formulated models, and experimental data show that the present model does evidence improvement in performance over previous models.

  • Publication: Kim, I.-C., Kaihatu, J. M.* (2021). “A Consistent Nonlinear Mild-Slope Equation Model.” Coastal Engineering, 170, 104006, doi: 10.1016/j.coastaleng.2021.104006.

2. Modified Frequency Distribution Function in Wave Breaking Dissipation

Once waves enter the surf zone, they become greatly asymmetric and skewed with wave breaking. A frequency-domain model and a probabilistic wave breaking model have been employed together to simulate the propagation of nearshore waves and to provide statistical quantities such as skewness and asymmetry. By correcting the frequency dependence function with the optimal breaking coefficient, the model results are in better agreement for the spectrum and higher-order statistics as well as the free surface elevation. As a consequence, the more dominant breaking mechanisms become, the more pronounced the contribution of this modification is.

3. A Consistent Nonlinear Mild-Slope Equation Model for Wide-Angle Water Waves

Application of the parabolic mild-slope equation model to wide-angle water wave propagation is limited to the small aperture. A higher-order parabolic evolution equation is derived for high accuracy at large wave angels. As an alternative, a consistent nonlinear mild-slope equation based on the angular spectrum model is suggested. Two newly developed models are tested for accuracy in describing wave pattern by a refractive focal lens as well as an elliptic shoal. To test the models’ applicability to wide-angle water waves, we compare wave patterns behind the circular shoal with several incidence angles.

4. Spreadsheet Calculators for Stability Number of Armor Units Based on Artificial Neural Network Models

an accurate easy-to-use ANN-based model is developed. The stability number is calculated by ensemble-averaging the outputs of 500 ANN models which were developed with different training data. The accuracy of the model is markedly improved compared with previous empirical formulas or ANN models. In addition, a spreadsheet calculator is provided so that engineers can easily use the model without deep knowledge of ANN. The calculator calculates the stability number by using the pre-determined weights and biases of the 500 ANN models.

  • Publication: Kim, I.-C., Suh, K.-D.* (2019). “Spreadsheet Calculators for Stability Number of Armor Units Based on Artificial Neural Network Models.” KSCE Journal of Civil Engineering, 23(12), 4961-4971, doi: 10.1007/s12205-019-0179-y.

RA.xls

5. Effect of Sea Level Rise and Offshore Wave Height Increase on Nearshore Waves and Coastal Structures

The relative changes in wavelength, refraction coefficient, shoaling coefficient, and wave height in the nearshore area are presented as functions of the relative changes in water depth and offshore wave height. The calculated relative changes in wave characteristics are then used to estimate the effect of sea level rise and offshore wave height increase on coastal structures by calculating the relative changes in wave run-up height, overtopping discharge, crest freeboard, and or weight of the structures.

  • Publication: Kim, I.-C., Suh, K.-D.* (2018). “Effect of sea level rise and offshore wave height change on nearshore waves and coastal structures.” Journal of marine science and application, 17(2), 192-207, doi: 10.1007/s11804-018-0022-8.