• 한국항해항만학회지
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• 제44권5호
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• pp.363-374
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• 2020

In the past, various research on the effects of waves generated by ships has been investigated. The most noticeable effect of the waves generated by a passing ship is the increase of the hydrodynamic forces and the unwanted large motion of the moored ship and high mooring forces that occur. Thus, it is crucial to investigate the effect of the waves generated by the passing ship near port on the motion of the moored ship and the tension of the mooring lines. A model test was performed with virtual ship-generated waves in a square tank at CWNU (Changwon National University). The IMU (Inertial Measurement Unit) and Optical-based system were used to measure the 6DOF (Six Degrees of Freedom) motion of the moored floater. Additionally the tension of mooring lines were measured by the tension gauges. The effects of the wave direction and wave height generated by the virtual ship-generated waves on the motion of the moored floater were analyzed.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2019년도 춘계학술대회
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• pp.98-100
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• 2019

In the past, there were several researchers investigating waves generated by a small boat. Wave generated by a ship can be divided into two distinct systems of waves, such as transverse and diverging waves. It is necessary to understand the behavior of a ship in waves generated by a small boat near port in the view point of ship safety. In this study, the motion of moored floater in waves generated by a small boat near port is investigated. The model test is performed in waves in a square tank in Changwon National University (CWNU). IMU and optical-based system which uses the technique of recording and capturing attitude with respect time are used for measuring 6DOF motion of the moored floater. In addition, tension gauges are used to measure the tension of mooring lines. The effect of waves generated by a small boat on motion of the moored floater near port is investigated through performing the model test in various wave directions of virtually but reasonably assumed wave scenarios.

• 해양환경안전학회지
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• 제14권4호
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• pp.297-301
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• 2008

선박의 항주에 의해 발생하는 항주파의 현장관측을 수행하였다. 파랑데이터는 선박의 항로에서 625m 이격된 지점에서 초음파식 파고계를 이용하여 12시간동안 5Hz로 관측하였다. 관측데이터 분석결과 이 해역의 파랑은 정상적인 기상상태에서는 항주파가 현저한 원인으로 분석되었으며, 대형여객선과 쾌속여객선의 항주파가 중첩될 때 최대파고 82.6cm로 관측되었다. 불규칙하지만 현저한 방향특성을 가지는 개방수역의 풍파와 비교하여 항내의 항주파는 매우 복잡한 형태를 나타냈다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2007년도 추계학술발표회
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• pp.29-33
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• 2007

선박의 항주에 의해 발생하는 항주파의 현장관측을 수행하였다. 파랑데이터는 선박의 항로에서 625m 이격된 지점에서 초음파식 파고계를 이용하여 12시간동안 5Hz로 관측하였다. 관측데이터 분석결과 이 해역이 파랑은 정상적인 기상상태에서는 항주파가 현저한 원인으로 분석 되었으며, 대형여객선과 쾌속여객선의 항주파가 중첩될 때 최대파고 82.6cm로 관측되었다. 불규칙하지만 현저한 방향특성을 가지는 개방수역의 풍파와 비교하여 항내의 항주파는 매우 복잡한 형태를 나타냈다.

• 한국해양공학회지
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• 제25권6호
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• pp.23-28
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• 2011

In this paper, a new generation method for ship induced waves is proposed using the fully non-linear 3-D numerical model with non-reflected wave generation system (LES-WASS-3D). A ship induced wave generated by the newly proposed method is examined in comparison with that obtained by an empirical formula. It is then shown that there is a good agreement in free surface the elevation between them. As a result, it is revealed that a ship induced wave in a 3-D numerical wave field can be simulated well using LES-WASS-3D.

• 한국항해항만학회지
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• 제33권2호
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• pp.105-110
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• 2009

Shipwaves am have harmful effects on ships working on the sea, in a harbour or navigational channel and caused beach erosion, seawall destruction. This study aims to investigate describe the characteristics of the wave pattern generated by an individual model ship tested at different velocities and hull forms for a given water depth and to investigate the variations at a given distance from the sailing line under the same conditions. As a result, the angles a's by model ship tests are smaller than those by real ship ones. Wave heights decreases with an increasing the mid-ship cross sectional area $A_s$. The maximum wave height and period increase rapidly in the subcritical speed, and beyond the critical speed the height and period decrease with increasing depth Froude number. And the period keeps constant with the distance from the sailing line.

• 항공우주시스템공학회지
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• 제8권3호
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• pp.14-19
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• 2014

When a helicopter lands on a ship deck in high sea states, one of main difficulties is the ship motion by sea wave, In case of a manned helicopter, a pilot lands a helicopter on the deck during quiescent period of ship motion, which is perceived from different visual cues around landing spot. The capability to predict this quiescent period is very important especially for shipboard recovery of VTOL UAV in harsh environments. This paper describes how to predict heave motion of a ship for shipboard landing of a VTOL UAV. For simulation, ship motion by sea wave was generated using a 4,000 ton class US destroyer model. Heave motion of ship deck was predicted by applying auto-regression method to generated time series data of ship motion.

• Journal of Ship and Ocean Technology
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• 제12권1호
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• pp.16-27
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• 2008

The interaction between advancing ships and the waves generated by them plays important roles in wave resistances and ship motions. Wave breaking phenomena near the ship bow at different speeds are investigated both numerically and experimentally. Numerical simulations of free surface profiles near the fore bodies of ships are performed and visualized to grasp the general trend or the mechanism of wave breaking phenomena from moderate waves rather than concentrating on local chaotic irregularities as ship speeds increase. Navier-Stokes equations are differentiated based on the finite difference method. The Marker and Cell (MAC) Method and Marker-Density Method are employed, and they are compared for the description of free surface conditions associated with the governing equations. Extra effort has been directed toward the realization of extremely complex free surface conditions at wave breaking. For this purpose, the air-water interface is treated with marker density, which is used for two layer flows of fluids with different properties. Adaptation schemes and refinement of the numerical grid system are also used at local complex flows to improve the accuracy of the solutions. In addition to numerical simulations, various model tests are performed in a ship model towing tank. The results are compared with numerical calculations for verification and for realizing better, more efficient research performance. It is expected that the present research results regarding wave breaking and the geometry of the fore body of ship will facilitate better hull form design productivity at the preliminary ship design stage, especially in the case of small and fast ship design. Also, the obtained knowledge on the impact due to the interaction of breaking waves and an advancing hull surface is expected to be applicable to investigation of the ship bow slamming problem as a specific application.

• Journal of Ship and Ocean Technology
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• 제5권1호
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• pp.38-54
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• 2001

A finite difference method for calculating turbulent flow and surface wave fields around a ship model is evaluated through the comparison with the experimental data of a Series 60 $C_B$=0.6 ship model. The method solves the Reynolds-averaged Navior-Stokes Equations using the non-staggered grid system, the four-stage Runge-Kutta scheme for the temporal integration of governing equations and the Bladwin-Lomax model for the turbulence closure. The free surface waves are captured by solving the equation of the kinematic free-surface condition using the Lax-Wendroff scheme and free-surface conforming grids are generated at each time step so that one of the grid surfaces coincides always with the free surface. The computational results show an overall close agreement with the experimental data and verify that the present method can simulate well the turbulent boundary layers and wakes as well as the free-surface waves.

• 한국해안·해양공학회논문집
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• 제20권3호
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• pp.255-267
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• 2008

대표적인 상용 CFD 코드 중 하나인 FLOW-$3D^{(R)}$에 포함된 강체에 대한 6-자유도 운동을 적용한 음해법의 GMO 방법을 이용하여 항주파의 재현 가능성을 살펴보았다. 모델에 의한 항주파의 형상 재현시 depth Froude number에 따른 수평 파형이 잘 재현되었으며, 선박의 직선항로 항행시 일정한 수심인 경우와 실제 수심인 경우를 비교함으로써 모델이 수심에 따른 파형의 변화를 잘 재현함을 알 수 있었다. 또한, 모델에 의해 실제 수심조건에서 두 척의 선박이 교차 진행할 경우와 선박이 곡선항로를 항행할 경우에 대한 항주파를 잘 재현할 수 있음을 보였다. 따라서, FLOW-$3D^{(R)}$를 이용하여 항주파를 수치모의할 경우 관측을 통한 모델의 검 보정을 통해 항로와 항구에서의 항주파를 보다 정확하게 예측할 수 있을 것으로 판단된다.