• Title/Summary/Keyword: Directional wave

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Ocean Wave Forecasting and Hindercasting Method to Support for Navigational Safety of Ship (선박의 항행안전지원을 위한 파랑추산에 관한 연구)

  • Shin, Seung-Ho;Hashimoto, Noriaki
    • Journal of Navigation and Port Research
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    • v.27 no.2
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    • pp.111-119
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    • 2003
  • In order to improve navigational safety of ships, an ocean wave prediction model of high precision within a short time, dealing with multi-directional random waves from the information of the sea surface winds encountered at the planned ship's course, was introduced for construction of ocean wave forecasting system on the ship. In this paper, we investigated a sea disaster occurred by a stormy weather in the past. We analyzed the sea surface wind first and then carried out ocean wave hindercasting simulations according to the routes the sunken vessel. From the result of this study, we concluded that the sea disaster was caused by rapidly developed iou pressure system Okhotsk Sea and the predicted values by the third generation wave prediction model(WAM) was agreed well with the observed significant wave height, wave period, and directional wave spectrum. It gives a good applicability for construction of a practical on-board calculation system.

Ocean wave forecasting and hindercasting method to support for navigational safety of ship (선박의 항행안전지원을 위한 파낭추산에 관한 연구)

  • 신승호;교본전명
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2003.05a
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    • pp.147-156
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    • 2003
  • In order to improve navigational safety of ships, on ocean wave prediction model of high precision within a short time, dealing with multi-directional random waves from the information of the sea surface winds encountered at the planned ship's course, was introduced for construction of ocean wave forecasting system on the ship. In this paper, we investigated a sea disaster occurred by a stormy weather in the past. We analyzed the sea surface winds first and then carried out ocean wave hindercasting simulations according to the routes of the sunken vessel. From the result of this study, we concluded that the sea disaster was caused by rapidly developed low pressure system in Okhotsk Sea and the predicted values by the third generation wave prediction model(WAM) was agreed well with the observed significant wave height, was period, and directional wave spectrum. It gives a good applicability for construction of a practical on-board calculation system.

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Numerical Simulations of Rip Currents Under Phase-Resolved Directional Random Wave Conditions (위상을 포함한 다방향 불규칙파 조건에서의 이안류 수치모의)

  • Choi, Junwoo
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.27 no.4
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    • pp.238-245
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    • 2015
  • Recently, Choi et al.(2015) showed that a numerical simulation of the SandyDuck experiment under a directional random wave environment agreed well with the experimental data including the wave height distribution of the random waves, the well-developed longshore current and its energetic fluctuation. Based on the Boussinesq modeling, this study investigates the effect of the alongshore variations, which are induced by not only the field topography but also the phase interaction of multidirectional random waves in the surf zone wave field, on the rip currents. As a result, transient rip currents as well as topographical rip currents cause the complicated surfzone circulation and mixing process due to their interactions in a multi-directional random wave condition while the topographical rip currents are dominant in a monochromatic wave condition.

Analysis of Multi-directional Random Waves Propagating over Multi Arrayed Submerged Breakwaters as Varying Crown Widths (폭 변화에 따른 다열 불투과성 수중방파제를 통과하는 다방향 불규칙파랑 해석)

  • Kang, Gyu-Young;Jung, Jae-Sang;Jung, Tae-Hwa;Cho, Yong-Sik
    • Proceedings of the Korea Water Resources Association Conference
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    • 2007.05a
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    • pp.2113-2116
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    • 2007
  • In this study, transmission and reflection of multi-directional random waves propagating over multi-arrayed submerged breakwaters are investigated using eigenfunction expansion method. The numerical analysis on the wave energy reflection of submerged breakwaters with various crown widths is carried out. Strong wave reflection is occurred at the Bragg reflection condition of the peak frequency. When relative heights and crown widths of breakwaters are equal to 0.6 and 0.4h, respectively, more than 25% of wave energy is reflected to off shore.

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An Experimental Study on Millimeter Wave Band Radome for ELINT Directional Finding System (ELINT 방향탐지 시스템에 적용되는 밀리미터파 대역 레이돔에 대한 실험적 연구)

  • Kim, Tae-Hyun;Park, Boem-Jun;Lee, Jung-Hoon;Lee, Byung-Nam
    • Journal of the Korea Institute of Military Science and Technology
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    • v.15 no.2
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    • pp.161-168
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    • 2012
  • In this paper, we have experimentally studied on phase characteristics of airborne radome for ELINT directional finding system, because it is difficult to find theoretical solutions for phase error of the radome. Especially, we described the millimeter wave band radome that was fabricated with cyanate-ester material and its thickness was 2mm. We presented the phase error about millimeter band radome. That phase error is about 30 degrees for parallel and perpendicular polarization in the K-Ka band. That is reasonable value for the ELINT directional finding system.

Analysis of the Wave Exciting Forces and Steady Drift Forces on a Tension Leg Platform in Multi-directional Irregular Waves (Frequency Domain Analysis) (다방향 불규칙파중의 인장계류식 해양구조물에 작용하는 파강제력 및 정상표류력 해석(주파수영역 해석))

  • 이창호
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.37 no.1
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    • pp.35-44
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    • 2001
  • A numerical procedure is described for simultaneously predicting the wave exciting forces and drift forces on a Tension Leg Platform (TLP) in multi-directional irregular waves. The numerical approach is based on a three dimensional source distribution method to the wave exciting forces, a far-field method to the steady drift forces and a spectral analysis technique of directional waves. The spectral description for the linear system of TLP in the frequency domain is sufficient to completely define the wave exciting forces and steady drift forces. This is because both the wave inputs and the outputs are stationary Gaussian random process of which the statistical properties in the amplitude domain are well known. Numerical results of steady drift forces are compared with the experimental and numerical ones, which are obtained in the literature. The results of comparison confirmed the validity of the proposed approach.

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Wave propagation of bi-directional porous FG beams using Touratier's higher-order shear deformation beam theory

  • Slimane Debbaghi;Mouloud Dahmane;Mourad Benadouda;Hassen Ait Atmane;Nourddine Bendenia;Lazreg Hadji
    • Coupled systems mechanics
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    • v.13 no.1
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    • pp.43-60
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    • 2024
  • This work presents an analytical approach to investigate wave propagation in bi-directional functionally graded cantilever porous beam. The formulations are based on Touratier's higher-order shear deformation beam theory. The physical properties of the porous functionally graded material beam are graded through the width and thickness using a power law distribution. Two porosities models approximating the even and uneven porosity distributions are considered. The governing equations of the wave propagation in the porous functionally graded beam are derived by employing the Hamilton's principle. Closed-form solutions for various parameters and porosity types are obtained, and the numerical results are compared with those available in the literature.The numerical results show the power law index, number of wave, geometrical parameters and porosity distribution models affect the dynamic of the FG beam significantly.

Design of a optimum structure for Ultrasonic Linear Motor using a travelling wave (진행파를 이용한 직선형 초음파 모터의 최적구조 설계)

  • 김연보;한우석;노용래
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.4
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    • pp.280-285
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    • 2000
  • The conventional ultrasonic linear motors developed so far utilize a standing wave and are of a pi-type or a hybrid transducer type structure. Traveling wave type bi-direction linear motors have not been developed yet. This paper describes design of a new bi-directional ultrasonic linear motor working by means of a traveling wave. With the finite element method we design and verify validity of the new structure. And we determine its optimal structure size of design variables material and boundary conditions for proper generation of the traveling wave.

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On Statistical Properties of the Extreme Waves in Hong-do Sea Area During Typhoons (홍도 해역에서 태풍 중 극한파의 통계적 특성에 대한 연구)

  • Ryu Hwanajin;Kim Do Young
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.7 no.1
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    • pp.47-55
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    • 2004
  • In this paper, The statistical properties of ocean waves in the sea area of Hong-do, Korea are examined based on 1998-2002's wave data from a directional wave buoy. Wave data aquisition rate, mean wave heights, frequency of wave direction are summarized. Wave height and period scatter diagrams and n-year return period wave heights are estimated. Wave periods of maximum wave heights are also estimated. Large amplitude wave characteristics during the typhoon Prapiroon in 2000, Rusa in 2002 are also examined.

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Nonlinear Interaction of Directional Irregular Waves (비선형 간섭을 고려한 다방향 불규칙파의 해석)

  • 홍기용
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.7 no.3
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    • pp.209-218
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    • 1995
  • Nonlinear interaction between directional wave components is theoretically analyzed in deep water. The perturbed solution for an irregular wave is derived accurate up to the third order of the wave steepness and it is shown that the wave characteristics are modulated due to the nonlinear interaction. The convergence rate of the perturbed solution depends on not only wave steepness but also wavelength ratio between wave components. The long-wave component of the perturbed solution converges rapidly. while the short-wave solution converges slowly or diverges. The short wave properties in a broad-band wave spectrum cannot accurately be obtained by the conventional wave-mode method because it fails to properly describe the modulation of short-wave frequency caused by the nonlinear interaction with much longer wave.

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