• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.209-212
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• 2002

Since Berkhoff proposed the mild-slope equation in 1972, it has widely been used for calculation of shallow water wave transformation. Recently, it was extended to give an extended mild-slope equation, which includes the bottom slope squared term and bottom curvature term so as to be capable of modeling wave transformation on rapidly varying topography. These equations were derived by integrating the Laplace equation vertically. In the present study, we develop a finite element model to solve the Laplace equation directly while keeping the same computational efficiency as the mild-slope equation. This model assumes the vertical variation of wave potential as a cosine hyperbolic function as done in the derivation of the mild-slope equation, and the Galerkin method is used to discretize . The computational domain was discretized with proper finite elements, while the radiation condition at infinity was treated by introducing the concept of an infinite element. The upper boundary condition can be either free surface or a solid structure. The applicability of the developed model was verified through example analyses of two-dimensional wave reflection and transmission. .

• 한국해안해양공학회지
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• 제10권4호
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• pp.174-186
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• 1998

본 연구에서는 지배방정식으로 확장형 완경사방정식을 사용하고 무한요소를 이용하여 방사조건을 처리하는 Galerkin 유한요소 모형을 수립하였다. 수립된 모형의 타당성과 적용성을 입증하기 위하여 Ippen and Goda((1963)의 완전개방 직사각형 모형항만에서의 항만 공진과 Sharp(1968) 및 Chandrasekera and Cheung(1997)의 원형 천뢰상을 전파하는 파랑 변형에 대한 수치해석을 실시하였다. 수리모형실험 및 복합요소 모형에 의한 결과와의 비교를 통하여 본 모형이 급경사 지형에도 매우 양호한 결과를 제시함을 확인하였다. 마지막으로 방파제의 대안으로 고려될 수 있는 원형 해저 우물을 설정하고 이를 지나는 파의 변형 특성을 검토하였다.

• 한국항해항만학회지
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• 제31권7호
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• pp.579-587
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• 2007

Samchunpo(Sin Hyang) Harbor is located in the bay of Sa Chun, the central south coast of Korean peninsula. The harbor and coastal boundaries have been protecting by natural coastal islands and shoals. Currently, The Sin Hyang harbor needs maintenance and renovation of the sheltered structures against the weather deterioration and typhoon damages. Consequently to support this, the calculation of accurate design wave through the typhoon wave attack is necessary. In this study, calculation of incident wave condition is simulated using steady state spectrum energy wave model(wide area wave model) from 50 years return wave condition. And this simulation results in wide offshore area were used for the input of the extended mild slope wave model at the narrow coastal area. Finally, the calculation of design wave at Sin Hyang harbor entrance was induced by Boussinesq wave model(detail area wave model) simulation. The numerical model system was able to simulate wave transformations from generation scale to shoreline or harbor impact. We hope these results will be helpful to the engineers doing placement, design, orientation, and evaluation of a wide range of potential solutions in this area.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 추계학술대회 논문집
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• pp.117-121
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• 2001

For the effective development or preservation of Tokdo, the natural environments in the ambient sea area should be well investigated. The wave deformations and wave breaking in the vicinity have much affected the bottom morphology of Tokdo as well as its ecological environment. The present study investigates the wave deformations and wave breaking through a numerical model. The final goal is to provide the fundamental wave data for the effective development or preservation of Tokdo in future. The extended mild slope equation was applied to Tokdo sea area for three different deep water wave conditions (S, SSE, NNE directions). The results showed that for the S and SSE directions the wave heights in the area between the east island and the west island were very low with the level of 1~2m, but for the NNE direction they appeared pretty high with 3~4m, In the sea area near the northwest of west island, the wave heights were low to be 1~3m for all three directions of deep water wave.

• 한국항해항만학회지
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• 제28권7호
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• pp.619-627
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• 2004

Introduction of wave model, considered the effect of shoaling, refraction, diffraction, partial reflection, bottom friction, breaking at the coastal waters of complex bathymetry, is a very important factor for most coastal engineering design and disaster prevention problems. As waves move from deeper waters to shallow coastal waters, the fundamental wave parameters will change and the wave energy is redistributed along wave crests due to the depth variation, the presence of islands, coastal protection structures, irregularities of the enclosing shore boundaries, and other geological features. Moreover, waves undergo severe change inside the surf zone where wave breaking occurs and in the regions where reflected waves from coastline and structural boundaries interact with the incident waves. Therefore, the application of mild-slope equation model in this field would help for understanding of wave transformation mechanism where many other models could not deal with up to now. The purpose of this study is to form a extended mild-slope equation wave model and make comparison and analysis on variation of harbor responses in the vicinities of Ulsan Harbor and Ulsan New Port, etc. due to construction of New Port in Ulsan Bay. We also considered the increase of water depth at the entrance channel by dredging work up to 15 meters depth in order to see the dredging effect. Among several model analyses, the nonlinear and breaking wave conditions are showed the most applicable results. This type of trial might be a milestone for port development in macro scale, where the induced impact analysis in the existing port due to the development could be easily neglected.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 Asia Navigation Conference
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• pp.217-225
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• 2004

Introduction of wave model, considered the effect of shoaling, refraction, diffraction, partial reflection, bottom friction, breaking at the coastal waters of complex bathymetry, is a very important factor for most coastal engineering design and disaster prevention problems. As waves move from deeper waters to shallow coastal waters, the fundamental wave parameters will change and the wave energy is redistributed along wave crests due to the depth variation, the presence of islands, coastal protection structures, irregularities of the enclosing shore boundaries, and other geological features. Moreover, waves undergo severe change inside the surf zone where wave breaking occurs and in the regions where reflected waves from coastline and structural boundaries interact with the incident waves. Therefore, the application of mild-slope equation model in this field would help for understanding of wave transformation mechanism where many other models could not deal with up to now. The purpose of this study is to form a extended mild-slope equation wave model and make comparison and analysis on variation of harbor responses in the vicinities of Ulsan Harbor and Ulsan New Port, etc. due to construction of New Port in Ulsan Bay. This type of trial might be a milestone for port development in macro scale, where the induced impact analysis in the existing port due to the development could be easily neglected.

• 한국해안해양공학회지
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• 제13권2호
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• pp.149-157
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• 2001

Nadaoka et al.에 의해 유도된 약 비선형 완경사 파동방정식을 급경사 지형에 적용할 수 있도록 바닥경사 곡률항과 바닥경사 제곱항을 포함하는 확장형 파동방정식을 유도하였다. 유도된 확장형 파동방정식의 선형식에 대해 일차원 유한차분 수치모형을 구성하고, 다양한 경사를 가치는 평면 경사지형에 의한 파의 반사에 대해 유도된 식과 수치모형을 검사하였다. 본 연구의 수치해와 기존의 여러 수치모형의 결과를 비교하여 본 결과, 급변수심에 대한 바닥경사 곡률항과 바닥경사 제곱항을 완전히 포함하여 원래의 Nadaoka et al. 식보다 정도가 상당히 개선되었다.

• 한국항만학회지
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• 제7권1호
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• pp.79-88
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• 1993

This study deals with the case of a fixed floating structure(FFS) at the mouth of a rectangular harbor under the action of waves represented by the linear wave theory. Modified forms of the mild-slope equation is applied to the propagation of regular wave over constant water depth. The model is extended to include bottom friction and boundary absorption. A hybrid element approximation is used for calculation of linear wave oscillation in and near coastal harbor. Modification of the model was necessary for the FFS. For the conditions tested, the results of laboratory experiments by Ippen and Goda(1963), and Lee (1969) are compared with the calculated one from this model. The cases of flat cylinderical structures, both fixed and floating, were taken to be in an intermediate water depth.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 2003년도 한국해안해양공학발표논문집
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• pp.44-52
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• 2003

항만 및 해안의 이용과 개발 그리고 연안해역공간에서 발생하는 각종 재해를 예방하는 측면에서 볼 때 해안에서 형성되는 여러 물리적인 현상들을 정확하게 이해하고 해석하여 필요에 따라 적절히 활용할 수 있는 것이 무엇보다도 중요한 과제이다. (중략)

• 한국수자원학회논문집
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• 제31권6호
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• pp.845-854
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• 1998

Ebersole(1995)의 접근법을 사용하여 Massel(1993)의 확장형 완경사방정식에서 유도되는 eikonal 식과 파랑 에너지전송식과 또한 파수의 비회전성을 이용하여 파랑변형을 예측하였다. 완경사방정식에 무시되었으나 확장형 완경사방정식에 고려된 고차의 수심변화 효과, 즉 수심경사의 제곱 및 수심의 곡률이 고려되면 수심변화가 심한 경우에 더 정확한 해석이 될 것이라는 예측이 수치실험 결과 제대로 나타나지 않았다. 이는 수심변화가 심한 경우 eikonal 식에서 고려된 회절의 효과가 제대로 반영되지 않아서 해석결과에 오류가 발생하는 것이 아닌가 판단된다.