• Title/Summary/Keyword: incident waves

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Wave Reflection and Transmission Coefficients of Rubble Mound Breakwaters under Oblique Incident Waves (경사입사파랑중의 사석방파제에 의한 반사율과 투과율에 관한 연구)

  • 배기성;김도삼
    • Journal of Ocean Engineering and Technology
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    • v.15 no.1
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    • pp.31-35
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    • 2001
  • By applying the Boundary Integral Equation Method (BIEM) to obliquely incident for Rubble Mound Breakwater (RMB), wave reflection and transmission the coefficients are studied numerically. The validity of and the present BIEM is confirmed by comparing it with 1)numerical results of the eigenfunction expansion method of Dalrymple et al.(1991), and 2)numerical results of the BIEM of Kojima et al.(1988). Therefore, the characteristics of RMB for obliquely incident waves are investigated according to the variations of the wave period, equivalent linear nondimensional friction coefficient and direction of incident waves. It is revealed that the wave transformations of obliquely incident waves are different from those of normally incident waves.

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BRAGG RESONANT REFLECTION OF OBLIQUELY INCIDENT WATER WAVES

  • Cho, Yong-Sik
    • Water Engineering Research
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    • v.1 no.1
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    • pp.75-81
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    • 2000
  • The bragg reflection of obliquely incident monochromatic water waves propagating over a sinusoidally varying topography is theoretically investigated in this study. The eigenfunction expansion method is first employed to calculate reflection coefficients of water waves due to depth changes. A reasonable agreement is observed. Obtained reflection coefficients of normally incident waves are compared with laboratory measurements. Reflection coefficients of obliquely incident waves are then calculated. The wavenumber providing the Bragg reflection agrees well with analytical predictions.

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A Study on the Nonreciprocal Transmissivity of a Photorefractive Crystals (광굴절 결정체의 비가역적 투과도에 관한 연구)

  • 조제황;김은수;양인응
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.8
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    • pp.1257-1261
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    • 1989
  • The propagation of electromagnetic waves in a photorefractive crystal is considered. The electromagnetic waves(i.e. TE waves and TM, waves) incident upon the crystal at any incident angle are coupled with reflected waves due to the Fresnel's reflectance in the photorefractive crystal. This coupling leads to a nonreciprocal optical transmissivity. About some incident angles, the optical transmissivity of TE and TM waves in regard to the coupling strength is investigated.

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Behavior of Regular Waves and Multi-Directional Random Waves Passing a Breakwater (방파제를 통과하는 규칙파와 다방향 불규칙파랑의 거동)

  • Park, Sang-Il;Park, Jin-Ho;Cho, Yong-Sik
    • 한국방재학회:학술대회논문집
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    • 2008.02a
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    • pp.439-442
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    • 2008
  • Diffraction of multi-directional random waves passing semi-infinite breakwater is investigated by using analytic solution derived by Penny and Prices(1952). An irregylarity of period and incident angle of waves and regular periods for regular waves are considered in addition by expanding from the past study which used only monochromatic wave in general. The Bretschneider-Mitsuyasu frequency spectrum and Mitsuyasu directional spectrum are used for incident waves. And diffraction of multi-directional random waves is reappeared by decomposing numerical results of several monochromatic waves which have variable period and incident angle. Analytic solution on the diffraction of regular waves and multi-directional random waves calculated in this study.

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Hydraulic and Numerical Experiments of Stem Waves along a Vertical Wall (직립벽을 따른 연파의 수리 및 수치실험)

  • Lee, Jong In;Yoon, Sung Bum
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.4B
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    • pp.405-412
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    • 2006
  • This study investigates the characteristics of stem waves along a vertical wall generated by obliquely incident monochromatic waves through laboratory experiments conducted in a wave basin and numerical simulations using parabolic approximation equations. The investigation is focused on the nonlinear effect of incident waves on the propagation characteristics of stem waves. Numerical results are compared with laboratory measurements and good agreements are obtained. The main results of this study show that the normalized stem wave height along the wall decreases and the stem width increases as the angle of incident waves decreases or the nonlinearity of the incident waves increases.

A Numerical Study on Pontoon Type Floating Breakwaters in Oblique Waves

  • Kim, Do-Young
    • International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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    • v.3 no.1
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    • pp.23-28
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    • 2000
  • A numerical investigation was made to examine characteristics of rectangular pontoon type floating breakwaters in oblique waves. Sway and heave wave exciting forces, roll moment acting on the floating breakwater and three motion reponses decrease as the incident wave angle increases for the most of the wave ranges. There exists a minimum wave transmission coefficient which is a function of wave frequency. In short wave range wave transmission coefficient increases as the incident wave angle increases. In long wave range, however, wave transmission coefficient decreases as the wave incident angle increases.

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Numerical Analysis of Waves Profiles coming with Oblique Angle to Permeable Submerged Breakwater on the Porous Seabed

  • Kim, Nam-Hyeong;Woo, Su-Min
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2013.06a
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    • pp.275-276
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    • 2013
  • This analysis method is based on the wave pressure function with the continuity in the analytical region including fluid and porous structures. Wave profiles coming with oblique angle to permeable submerged breakwater on the porous seabed are computed numerically by using boundary element method. When compared with the existing results for the oblique incident wave, the results of this study show good agreement. The results indicate that wave profiles own high dependability regarding the change of oblique incident waves and permeable submerged breakwater on the porous seabed. Therefore, the analysis method of this study are estimated to be applied as an accurate numerical analysis referring to oblique incident waves and permeable submerged breakwater on the porous seabed in real sea environment.

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Electromagnetic Scattering by a Plasma Column Moving in the Perpendicular Direction to Its Axis (축과 수직방향으로 운동하는 프라즈마원주에 의한 평면전자파의 산란)

  • 구연건
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.8 no.1
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    • pp.17-22
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    • 1983
  • Scattering of obliquely incident plane electromagnetic waves by an isotropic plasma coumn which is moving uniformly in the perpendicular direction to its axis is treated analytically on the basis of Lorentz transform and boundary conditions. The scattered field, the total scattering cross-section, the rader cross-section, and the angular distribution of the scattered power for the incident plane waves polarized arbitrarily are derived to find the function of the moving velocity of the plasma column and of the angle of the incident plane waves and to find the scattered field of the H-waves more distinguishable than the E-waves.

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Numerical Analysis of Waves coming with Oblique Angle to Submerged Breakwater on the Porous Seabed (침투층 위의 잠제에 경사각을 가지고 입사하는 파랑의 수치해석)

  • Kim, Nam-Hyeong;Woo, Su-Min
    • Journal of Navigation and Port Research
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    • v.37 no.3
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    • pp.283-289
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    • 2013
  • Wave profiles coming with oblique angle to trapezoidal submerged breakwater on the porous seabed are computed numerically by using a boundary element method. The analysis method is based on the wave pressure function with the continuity in the analytical region including fluid and structure. When compared with the existing results on the oblique incident wave, the results of this study show good agreement. The fluctuation of wave profiles is increased in the rear of the submerged breakwater due to the increase of the transmission coefficient, as the incident angle increases. In addition, in the case of the wave profiles passing over the submerged breakwater on porous seabed, it is able to verify that the attenuation of wave height occurs more significantly due to the wave energy dissipation than that of passing over the submerged breakwater on the impermeable seabed. The results indicate that wave profile own high dependability regarding the change of oblique incident waves and porous seabed. Therefore, the results of this study are estimated to be applied as an accurate numerical analysis referring to oblique incident waves and porous seabed in real sea environment.

Stem Wave Analysis of Regular Waves using a Boussinesq Equation (Boussinesq 방정식을 이용한 규칙파의 연파해석)

  • Lee, Jong-In;Kim, Young-Taek;Yoon, Sung-Bum
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.19 no.5
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    • pp.446-456
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    • 2007
  • Numerical analyses of stem waves, the interaction between incident and reflected waves of obliquely incident regular waves along a vertical wall in a constant water depth, are presented. For the numerical model of the analysis, the two-layer Boussinesq equations developed by Lynett and Liu(2004a,b) are employed. Numerical results are compared with both laboratory measurements and those obtained using parabolic approximation model. The overall comparisons between the results from the two numerical models and the experiments are good. However, the two-layer Boussinesq model is more accurate than the parabolic approximation model as the angle of incident waves increases. In particular, the higher harmonic generation due to the wave nonlinearity is captured only in the Boussinesq model.