• 한국해양공학회지
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• 제21권1호
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• pp.18-24
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• 2007

When the wind blows strong, most waves are breaking at sea. Breaking waves occur by exceeding the limitation of wave steepness (wave height/wave length = 1/7). Because a wave of single angular frequency couldn't generate the breaking phenomena at a two-dimensional ocean engineering basin, the breaking wave can be generated by the superposition of waves with various angular frequencies based on dispersion relation. This study investigates the particle kinematics in the breaking wave and the magnitude of the breaking wave exciting force at the breaking point and breaking region. We compare the regular wave load in a regular wave, which has same specifications (wave height, period and length), with the breaking waveload. Also, the experimental results of wave exciting force and particle velocity are investigated, by comparison with the analytic results using the potential theory.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.96-101
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• 2004

When the wind blows hard, most waves are breaking in sea. Breaking waves occur, exceeding limitation of wave steepness(wave height/wave length=l/7). Because a wave of single angular frequency couldn't generate the breaking phenomena at two dimensional ocean engineering basin, the breaking wave can be generated by the superposition of waves with various angular frequencies. We research how are the particle kinematics in the breaking wave and the magnitude of the breaking wave exciting force. We compare the force in a regular wave which has same specifications(wave height, period and length) as the breaking wave. Also the experimental results of wave exciting force and particle velocity are investigated by comparison on the analytic results using the potential theory.

• 한국해안해양공학회지
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• 제2권2호
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• pp.96-103
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• 1990

A local Iribarren number is suggested for the universal use of breaker type classification, which relates the bed slope to the wave steepness, both being given from the breaking point. The existing Iribarren number uses the wave length at an offshore point, while the local Iribarren number uses the wave length at the breaking point so that it can imply any influences due to current interaction and diffraction. The modified form of Miche's breaking criterion includes 고 breaking parameter which may be related to the local Iribarren number. Using the modifiedform of Miche's criterion with the local Iribarren number, the inclusion of Doppler effect seems to describe well the wave breaking mechanism in a current-interacted flow on a sloping beach without any additional effects implemented.

• 한국해안해양공학회지
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• 제4권3호
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• pp.178-186
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• 1992

어떤 특정 위치에서 파속이 빠른 파가 느린 파를 추월하도록 여러가지 다른 주파수의 파를 중첩시킴으로써 심해쇄파에 대한 실험을 수행하였다. 예상 쇄파지점 근처에서 큰 파고를 갖는 붕괴파와 권파를 조파시켰다. 쇄파점에 가까워 질수록 붕괴파와 권파의 파형경사가 뚜렷하게 증가되었고 쇄파 후에는 감소되었다. 격렬한 권파시에는 파형경각가 보다 더 증가됨을 볼 수 있었다. 파군 중의 기본적인 주파수들은 파낭의 전파과정이나, 특히 격렬한 권파시에도 별 변동이 없었다.

• 한국해안해양공학회지
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• 제7권2호
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• pp.135-140
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• 1995

쇄파감쇠과정을 포함한 파랑변형이 규칙파에 의해 관찰되었다. 파랑변형의 기초data를 얻기 위해 사면경사 1/20 및 1/10을 step에 연결한 지형을 설치하여 실험을 실시하였다. 쇄파 후 파고는 감소하기 시작하여 쇄파점으로부터 임의의 거리에 일정한 값을 나타낸다. 본 연구는 안정파고에 관한 일반식을 가지고 신파랑변형모델을 제안한다. 모델은 실험치와 비교하여 급격한 수심변화에도 쇄파 전후의 파랑특성을 잘 설명함을 알 수 있었다.

• 한국해양공학회지
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• 제17권6호
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• pp.1-6
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• 2003

Wave energy dissipation and energy transfer between wave components, during the directional wave breakings, are investigated. Directional incipient and plunging breakers were generated by focusing the multi-frequency and multi-directional wave components at a designed location, based on a constant wave amplitude and a constant wave steepness frequency spectrum. The time series of surface wave elevation was measured at 9 different locations around the wave focusing point, using a wave gauge array. In order to examine the variation of the directional spreading function, the horizontal velocity of fluid motion was also measured. By comparing energy spectrums, before and after the breaking, the characteristics of energy dissipation and energy transfer, caused by wave breaking, are investigated. Their dependencies on directionality, as well as frequency, are analyzed. The breakings significantly dissipate wave energy, through energy transfer, in the upper region of the peak-frequency band, while enhancing wave energy in the low-frequency band.

• 한국해양공학회지
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• 제24권1호
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• pp.116-122
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• 2010

The aim of this study is to examine the effects of shape and plane arrangement of submerged breakwaters on 3-D wave breaking characteristics over them. First, the numerical model, which is able to consider the flow through a porous medium with inertial, laminar, and turbulent resistance terms, i.e. simulate directly WAve Structure Seabed/Sandy beach interaction, and can determine the eddy viscosity with a LES turbulent model in a 3-Dimensional wave field (LES-WASS-3D), has been validated by a comparison with Goda's equation for breaking wave heights. And then, using the numerical results, the wave breaking points over the crest of submerged breakwaters have been examined in relation to the shape and plane arrangement of submerged breakwaters. Moreover, the wave height distribution and upper flow around submerged breakwaters have been also discussed, as well as the distribution of the wave breaking points over the beach.

• 한국해안해양공학회지
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• 제6권2호
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• pp.157-163
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• 1994

비선형 심해파의 전개과정을 통하여 그리고 어떤 특정한 위치에서 파속이 빠른 파가 느린 파를 추월하도록 하여 파의 중복을 유도함으로써 심해쇄파를 발생시키는 실험을 수행하였다. 2차원과 3차원적인 파랑의 불안정상태와 그로 인한 쇄파의 발생이 비선형 심해파의 전개과정에서 관찰되었고 또한 예상 쇄파지점에서 출 파고를 갖는 붕괴파(spilling waves)와 권파(plunging waves)를 관찰하였다. 비선형 심해파의 전개에서는 파랑이 거의 초기에너지를 가지고 전개하였으며 쇄파가 일어난 후에는 많은 에너지가 감소하는 것으로 나타났다. 붕괴파와 권파에서도 쇄파후의 에너지의 감소가 나타났지만 특히 격렬한 권파에서의 에너지감소가 두드러지게 관찰되었다.

• 산업기술연구
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• 제16권
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• pp.83-95
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• 1996

The equilibrium beach profiles with the effects of random waves and nonuniform grain size in the surf zone are derived from the Thornton and Guza(1983)'s energy dissipation model. The derived beach profiles are the functions of the breaking wave strength, the frequency of the incident wave, and the wave induced-energy dissipation at breaking point. It is not confirmed that the equilibrium beach profiles are better agreement with the measured profiles than the classical profiles. However, the characteristic of the changes of the beach profiles with respect to the breaking wave stgrngth and the frequency of the incident wave can be analyzed which has not been studied by the classical model.

• Journal of Hydrospace Technology
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• 제2권1호
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• pp.1-9
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• 1996

We consider the following two questions mainly in this study. First one is how the free surface hayes affect the lift of a shallowly submerged moving body. For this matte., we reinterpret the theoretical results of Kochin(1936), and point out that the high Froude number approximation is not always on the safer side. Second one is what sort of dimensionless parameters determine the occurrence of wave breaking behind a moving submerged body. Temporarily before getting a better answer, we propose that the two-parameter-plane, namely, the plane of the Froude number and the square root of the ratio of the submerged depth and the body length, may be used for predicting the possibility of wave breaking behind the submerged body. A region in the parameter plane is put forth as that of wave breaking, and the validity of this proposal is shown by its agreement with the existing experimental data of Parkin et al(1955) and those of Duncan(1983). Finally, linear and nonlinear numerical results are compared with the existing experimental data to see in what range of the parameters the linear and nonlinear theory case predict the wave field and the pressure on the body with reasonable accuracy. However, since the experimental data, which offer both the pressure and wave elevation for a submerged moving body, are very scarce, much cannot be attained through this comparative study. Hence, it is strongly recommended to carry out well planned experiments to get such data.