• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.17 no.1
• /
• pp.21-31
• /
• 2005

In this study, derivation is made of a one-grid source function for the extended Boussinesq equations of Nwogu (1993) in order to generate nonlinear waves internally. The energy velocity approach used in the line source method is verified analytically by the fractional step splitting method. The source function method is verified by generating accurately nonlinear waves as well as linear waves for horizontally one-dimensional cases. It is found that numerical solutions by the source function method are the same as those by the line source method.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
• /
• 2004.08a
• /
• pp.73-84
• /
• 2004

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.21 no.2
• /
• pp.182-190
• /
• 2009

For RANS equation model using VOF scheme Lin and Liu (1999) developed internal wave-maker method to generate target wave trains by using designed mass source functions of the continuity equation. By using this method studies on various numerical wave experiments has been achieved without the problem caused by wave reflection due to an external wave-maker. In this study, the wave-maker method to generate target wave trains by using a momentum source function was proposed. The computational results obtained by applying the mass and momentum source functions into FLUENT were compared with each other. To see its applicability, the hydraulic experiment of Luth et al. (1994) were numerically simulated and their measurements are compared with the computations, and the vertical variations of computed results were shown and investigated.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.20 no.3
• /
• pp.247-254
• /
• 2008

The double-peak normal distribution function (DPDF) suggested by Cho et al.(2004) has the problems that the extremely high and low tidal elevations are frequently generated in the Monte-Carlo simulation processes because the upper and lower limits of the DPDF are unbounded in spite of the excellent goodness-offit results. In this study, the modified DPDF is suggested by introducing the upper and lower value parameters and re-scale parameters in order to remove these problems. These new parameters of the DPDF are optimally estimated by the non-linear optimization problem solver using the Levenberg-Marquardt scheme. This modified DPDF can remove completely the unrealistically generated tidal levations and give a slightly better fit than the existing DRDF. Based on the DPDF's characteristic power, the over- and under estimation problems of the design factors are also automatically intercepted, too.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
• /
• 2001.08a
• /
• pp.30-36
• /
• 2001

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.6B
• /
• pp.379-385
• /
• 2012

Recent development of computing power and theoretical advances in computational fluid dynamics have made possible numerical simulations of water waves with full Navier-Stokes equations. In this study, an internal wave maker using the mass source function approach was combined with the level set finite element method for generation of waves. The model is first applied to the two-dimensional linear wave generation and propagation. Then, it is applied to the three-dimensional simulation of the same problem. To effectively utilize computational resources and enhance the speed of execution, parallel algorithms are developed and applied for the three-dimensional problem. The results of numerical simulations are compared with theoretical values and good agreements are observed.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.3 no.1
• /
• pp.1-13
• /
• 1991

A wave prediction model of DP type with shallow water effects is composed. An jntercomparison study of the deep water wave models has been made to clarify the capacity of this model which has source functions by Incur and propagation scheme by Gadd. It is shown that the growth rate of wave energy is rapid and. for asymmetrical wind fields. this model behaves well. In spite of various response pattern for the wind fields the energy distribution gives reasonable agreements with those of other models.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.4 no.2
• /
• pp.83-90
• /
• 1992

A wave prediction model of DP type with shallow water effects is presented. An intercom-parison study of the shallow water wave models has been made to verify applicability of this model which has source functions of Inoue, propagation scheme by Gadd and dissipation functions due to bottom friction. The energy distribution shows reasonable results and for the bottom friction JONS-WAP decay function seems to be more appropriate.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.8 no.2
• /
• pp.151-160
• /
• 1996

To construct the third generation model, nonlinear interaction was included in source terms. To calculate the nonlinear interaction, discrete interaction approximation to Boltzmann integral was used, as in WAM model. The general behavior and characteristics of nonlinear interaction were analyzed through the experiments for the durational growth and turning winds.

• Journal of KIISE
• /
• v.42 no.9
• /
• pp.1100-1108
• /
• 2015

Classes.dex, which is the executable file for android operation system, has Java bite code format, so that anyone can analyze and modify its source codes by using reverse engineering. Due to this characteristic, many android applications using classes.dex as executable file have been illegally copied and distributed, causing damage to the developers and software industry. To tackle such ill-intended behavior, this paper proposes a technique to encrypt classes.dex file using an AES(Advanced Encryption Standard) encryption algorithm and decrypts the applications encrypted in such a manner in order to prevent reverse engineering of the applications. To reinforce the file against reverse engineering attack, hash values that are obtained from substituting a hash equation through the combination of salt values, are used for the keys for encrypting and decrypting classes.dex. The experiments demonstrated that the proposed technique is effective in preventing the illegal duplication of classes.dex-based android applications and reverse engineering attack. As a result, the proposed technique can protect the source of an application and also prevent the spreading of malicious codes due to repackaging attack.