• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.23 no.4
• /
• pp.381-394
• /
• 2019

In this paper, we are extending fractional partial differential equations to fuzzy fractional partial differential equation under Riemann-Liouville and Caputo fractional derivatives, namely Variational iteration methods, and this method have applied to the fuzzy fractional wave equation with initial conditions as in fuzzy. It is explained by one and two-dimensional wave equations with suitable fuzzy initial conditions.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.20 no.1
• /
• pp.1-13
• /
• 2008

In the present work, wave transformation by vertical columns and its wave forces acting on them are discussed using a direct 3-D numerical model based on the VOF (Volume Of Fluid) method. The numerical results for wave transformations and wave forces are critically compared to an advanced experimental data, and provide the verification of the numerical model used in the present study. Overall model-data comparisons are good. After verification of the numerical model, it is used to simulate wave fields around dual vertical columns with arbitrary cross section, and the characteristics of nonlinear wave forces and wave transformations according to the variations of different cross section types of vertical columns, an interval of vertical columns and incident wave angle are discussed.

• Journal of applied mathematics & informatics
• /
• v.10 no.1_2
• /
• pp.119-130
• /
• 2002

An extended Jacobin elliptic function method is presented for constructing exact travelling wave solutions of nonlinear partial differential equations(PDEs) in a unified way. The main idea of this method is to take full advantage of the elliptic equation that Jacobin elliptic functions satisfy and use its solutions to replace Jacobin elliptic functions in Jacobin elliptic function method. It is interesting that many other methods are special cases of our method. Some illustrative equations are investigated by this means.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2004.05a
• /
• pp.241-248
• /
• 2004

In general, the salient features if the floating breakwater have excellent regulation of sea-water keeping the marine a1ways clean, up and dorm free movement with the incoming and outgoing tides, capable of being installed without considering the geological condition of sea-bed at any water depth, This study discusses the three dimensional wave transformation of the floating breakwater moored by catenary. Numerical method is based at the Green function method and eigenfunction expansion method. The validity of the present is confirmed by comparing it with the result of Ijima et a1.(1975) fer tensile maxed floating breakwater. According to the numerical results, drift and width of the floating breakwater affect at the wave transformation greatly, and incident wave of long period is well transmitted to the rear of the floating breakwater.

• Journal of the Society of Naval Architects of Korea
• /
• v.60 no.4
• /
• pp.266-277
• /
• 2023

In this study, fundamental research is conducted for the generation technique and analysis of multi-directional irregular waves in the Deep Ocean Engineering Basin (DOEB). A three-dimensional boundary element method-based numerical tank is implemented to perform wave generation simulations, and directional spectrum estimation is carried out using the results of simulations. The wave generation technique of the Snake type wave maker, generating multi-directional irregular waves, is implemented using the Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) algorithms. The wave generation technique is validated by comparing the wave spectrum from simulations and experiments. A Maximum Likelihood Method (MLM) based estimation code is developed for estimating the directional wave spectra. The multi-directional irregular waves are tested in the DOEB and the numerical tank, and directional wave spectra obtained from two methodologies are estimated and compared. A correction procedure for the directional distribution of multi-directional waves is established, and the possibility of correcting the directional spreading function using the numerical tank is validated.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.04a
• /
• pp.697-702
• /
• 1999

Among several non-destructive testing methods, ultrasonic pulse velocity method has been widely used for the evaluation of concrete strength. However, this method might not provide accurate estimated results since factors influencing the relationship between strength and wave velocity is not considered. In this study, the evaluation methods of concrete strength using compression wave velocities measured by either ultrasonic pulse velocity method or impact-resonance method are proposed. A basic equation is obtained by the linear regression with velocity vs. strength data at a specific age and then, ageing factor is employed in the equation to consider the difference of the increasing rate between wave velocity and strength. Strengths predicted by the proposed equation agree well with test results.

• Journal of Advanced Research in Ocean Engineering
• /
• v.1 no.3
• /
• pp.157-167
• /
• 2015

In order to provide simple and accurate wave theory in design of offshore structure, an analytical approximation is introduced in this paper. The solution is limited to flat bottom having a constant water depth. Water is considered as inviscid, incompressible and irrotational. The solution satisfies the continuity equation, bottom boundary condition and non-linear kinematic free surface boundary condition exactly. Error for dynamic condition is quite small. The solution is suitable in description of breaking waves. The solution is presented with closed form and dispersion relation is also presented with closed form. In the last century, there have been two main approaches to the nonlinear problems. One of these is perturbation method. Stokes wave and Cnoidal wave are based on the method. The other is numerical method. Dean's stream function theory is based on the method. In this paper, power series method was considered. The power series method can be applied to certain nonlinear differential equations (initial value problems). The series coefficients are specified by a nonlinear recurrence inherited from the differential equation. Because the non-linear wave problem is a boundary value problem, the power series method cannot be applied to the problem in general. But finite number of coefficients is necessary to describe the wave profile, truncated power series is enough. Therefore the power series method can be applied to the problem. In this case, the series coefficients are specified by a set of equations instead of recurrence. By using the set of equations, the nonlinear wave problem has been solved in this paper.

• International Journal of Highway Engineering
• /
• v.7 no.3 s.25
• /
• pp.63-69
• /
• 2005

For many years, the compressive strength of concrete has been regarded as an important index in determining concrete pavement quality. The compressive strength of the sample cores from the field has been used as quality index of concrete pavement. However, this process is time consuming and requires a lot of labor. Recently, the M-E Design Methodology in the pavement design based on the elastic modulus has been adopted. Therefore, several NDT methodologies have been adopted for QA/QC in the field and for the pavement design. Among various NDT methods, the wave propagation method can be used to measure the elastic modulus of concrete because the wave velocity is directly related to the elastic modulus. Therefore, in this study the wave propagation method was used for estimating the concrete modulus. The relationship between the compressive strength measured in he laboratory and the elastic modulus measured by the wave propagation method was analyzed, and the compressive strength was estimated from the elastic modulus for various mix types. The results showed that the relationship between the elastic modulus and the compressive strength was observed and the relationship varied depending on the aggregate types.

• Journal of Korea Multimedia Society
• /
• v.19 no.8
• /
• pp.1377-1385
• /
• 2016

Conventional X-band marine radar has been used as one of the effective tools for collecting and retrieving ocean surface information parameters for three decades. Several wave information extracting algorithms have been designed in such a way that they can be utilized for efficiently estimating sea surface wave parameters such as current velocities, wave direction, significant wave heights in VTS (Vessel Traffic Service). However, their performances are still restricted. For the purpose of overcoming the performance limits, in this paper, first the conventional algorithms are analyzed and their performances are compared, and then a new control algorithm is proposed. Furthermore, we try to improve the estimation performances of typical wave parameters including wave directions and significant wave heights by introducing linear regression model in the process of computing wave information extraction. Through several simulations with the X-band radar images, it is shown that the proposed method is very effective in estimating the wave information compared to the real measured buoy data.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.25 no.4
• /
• pp.244-254
• /
• 2013

In this study, a method has been developed for estimating the change of nearshore random waves in response to sea-level rise, by extending the method proposed for regular waves by Townend in 1994. The relative changes in wavelength, refraction coefficient, shoaling coefficient, and wave height for random waves are presented as functions of relative change in water depth. The changes in wavelength and refraction coefficient are calculated by using the significant wave period and principal wave direction in the regular-wave formulas. On the other hand, the changes in shoaling coefficient and wave height are calculated by using the formulas proposed for shoaling and transformation of random waves in the nearshore area including surf zone. The results are proposed in the form of both formulas and graphs. In particular, the relative change in wave height is compared with the result for regular waves.