• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.4
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• pp.266-273
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• 2016

Two-dimensional hydraulic experiments were performed to assess the impact of artificial seaweed on wave energy attenuation, and coastal erosion prevention. In this experimental study, erosion geometry and wave reflection coefficients were determined for normal and stormy incident waves, with and without artificial seaweed. The coastline of beaches without artificial vegetation was observed to retreat, and the longshore bar height increased in normal and stormy conditions. Through the introduction of artificial seaweed (of widths 0.8 m, and 1.6 m), the coastline was found to advance in the offshore direction due to material deposition. From these results, it is shown that artificial seaweed alters the cross-section of beaches, such that it is possible to prevent coastline erosion.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.473-476
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• 2006

천해역의 파랑발달에 대한 태풍경로의 영향력을 분석 하였다. 우리나라 남동해안에 주로 피해를 초래할 것으로 판단되는 태풍의 경로를 '남해안 상륙 후 내륙 통과'와 '대한해협통과'로 분류하고 각 경로에 따른 태풍규모와 파랑발달을 1956년 부터 2004년까지의 기상자료를 바탕으로 검토하였다. 태풍 경로의 영향력 분석은 천해역 파랑발달의 주요외력이 지형조건에 의해 결정되므로(즉, 폐쇄해역은 태풍의 바람장이 주요외력이며, 개방해역은 심해 전달파랑과 바람장의 영향을 동시에 받는다), 개방해역과 폐쇄해역의 경우로 나누어 수치모형실험을 통해 수행하였다. 실험조건은 태풍 "매미"의 강도와 특성 값을 기준으로 하였으며, 대상해역은 부산신항 인근해역과 원전항 인근해역을 개방형과 폐쇄형 해역으로 대별하여 실험을 수행하였다. 자료의 분석결과 최근 이상기후현상으로 태풍의 강도가 커지고 있음을 뒷받침 하는 근거는 찾아보기 힘들었으며, 2000년대 이후로 남해안에 상륙하는 경로'1'이 대한해협을 통과하는 경로(경로'2')보다 그 내습빈도가 커지고 있음을 볼 수 있었다. 태풍의 경로와 풍향이 같은 방향인 경로'1'일 때 에너지가 집중되어 태풍중심기압과 풍속과 파고의 증가가 함께 일어난다. 그러나 태풍의 경로와 풍속의 방향이 일치하지 않는 경로'2'의 경우는 에너지가 분산되므로 태풍중심기압과 풍속은 함께 증가하나 파랑에너지는 함께 발달하지 않는 것으로 보였다. 내습한 태풍의 강도를 경로별로 비교한 결과, 경로'1'이 경로'2'보다 큰 강도를 가지고 연악역에 영향을 미치는 것으로 판단되었다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.12
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• pp.1579-1584
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• 2011

This paper discusses an energy system that can convert wave energy into electrical energy. This wave energy generation system is movable and has 12 arms and one generator. A multibody dynamic model for this system is established by using kinematic constraints. A gear mechanism, several kinematic constraints, and force elements are included in the model. Wave forces are obtained numerically from the time domain formulation based on the Morison equation. The MSC/ADAMS program is employed to carry out dynamic analysis of the wave energy generation system. The dynamic behavior responses of this system are analyzed for design verification. According to the results of the dynamic analysis, the yaw motion is relatively stable and kinetic energy sufficient to generate electrical energy is obtained when the wave height exceeds 1m.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.6 no.2
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• pp.67-75
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• 1986

This paper introduces the nonlinear Stream Function Wave Theory for design waves efficiently to compute the wave energy and energy transport quantities and to analyze the effects of nonlinearities on them. The Stream Function Wave Theory was developed by Dean for case of the observed waves with assymmetric wave profiles and of the design waves with symmetric theoretical wave profiles. Dalrymple later improved the computational procedure by adding two Lagrangian constraints so that more efficient convergence of the iterative numerical method to a specified wave height and to a zero mean free surface displacement resulted. And the Stream Function coefficients are computed numerically by the improved Marquardt algorithm developed for this study. As the result of this study the effects of nonlinearities on the wave quantities of the average potential energy density, the average kinetic energy density result in overestimation by linear wave theory compared to the Stream Function Wave Theory and increase monotonically with decreasing $L^*/L_O$ and with increasing $H/H_B$. The effects of nonlinearities on the group velocity and the wavelength quantities result in underestimation by linear wave theory and increase monotonically with increasing $H/H_B$. Finally the effect of nonlinearity on the average total energy flux results in overestimation for shallow water waves and underestimation for deep water waves by linear wave theory.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.298-302
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• 2004

본 연구에서는 낙동강 하구역 해역에서의 폭풍 해일의 특성 및 이를 고려한 외해 압사파랑특성을 고찰하고 연안사주 전면의 입사파랑과 퇴적 특성과의 상호 관계를 고찰하였으며 천해역의 파랑변형을 예측할 수 있는 다방향 불규칙파 묘형을 구성하고 폭풍 해일고를 수심조건에 고려함으로써 하구역 해역에서의 파랑 변형계산을 2차원 평면수치모의실험을 수행하였다. 낙동강 하구역에서 서측에 위치하는 진우도 전면해역이 무명도 전면해역보다 약 1.0배에서 2.0배 크게 파고분포를 나타내었다. 이는 입사하는 파랑의 공간 분포가 사주전면에서 공간적으로 차이가 남을 나타내는 것으로 사주의 퇴적작용에 영향을 줄 것이라고 판단된다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.3 no.4
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• pp.223-234
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• 1991

In this paper, the harbor tranquility problem is analysed by an improved boundary integral equation method. The effect of the diffracted wave transformation induced by the breakwater and structures located at a harbor mouth is considered. Partial reflection concept is also used to consider energy dissipation effects. The present model is verified by comparing the results of the model for rectangular and semi-circular harbors with the analytic solutions. they show a reasonable agreement. Also the wave height distribution of the HUPO harbor computed using the present model agree well to those from the previous hydraulic model tests. It also shows a good agreement with the results from the time-dependent mild slope equation model.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.1
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• pp.39-44
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• 2009

To improve the accuracy of numerical simulation of wave trans- formation across the surf zone, nonlinear shoaling effect based on Shuto's empirical formula and breaking mechanism are induced in the elliptic modified mild slope equation. The variations of shoaling coefficient with relative depth and deep water wave steepness are successfully reproduced and show good agreements with Shuto's formula. Breaking experiments show larger wave height distributions than linear model due to nonlinear shoaling but breaking mechanism shows a little bit larger damping in 1/20 beach slope experiment.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.6
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• pp.511-520
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• 2007

WAM(WAve Model), deep water wave model has been extended to the region of shallow water, incorporating wave breaking, and triad wave interaction. To verify the model, numerical simulation of waves in Youngil bay, Pohang is performed and the simulated results show good agreements with measured wave data sets, one station at the mouth of bay and two stations inside the bay. As waves propagate toward the shore, wave height gradually diminishes by bottom friction and wave breaking, and wave direction, initially NE changes normal to the shore due to depth refraction.

• Journal of Radiation Protection and Research
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• v.12 no.1
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• pp.12-25
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• 1987

A basic multichannel analyser (MCA) system have been designed and constructed with the successive approximation type ADC (Analog to Digital Converter). Linear Gate, window, and palse stretcher consist of mainly linear and logic IC's, and are properly combined together to achieve short dead time and good linearity of the system. ADC 1211 (analysing time: $120{\mu}sec$) and S-RAM (static random acess memory) 6264 are used in ADC module. Two 6264 memories are connected in parallel in order to-provide enough counting capacity ($2^{16}-1$). Interfaced microcomputer Apple II controls this system and analizes the counted data. The system is tested by input pulses between 0V to 10V from oscillator.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.255-255
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• 2015

지진해일은 주기가 긴 파랑으로 방파제나 방호구조물에 의한 에너지 감소가 작은 특성이 있다. 또한, 범람구역의 구조물 밀집도 및 지형적 요인에 따라 범람영역, 침수심, 파력 등이 상이하게 나타나므로 유체흐름의 입체적 변화양상을 고려하여야 한다. 본 수리모형실험은 임원항을 대상으로 구조물에 작용하는 지진해일의 파력특성을 3차원수리모형실험을 통해 검토하고, 파력산정계수(${\alpha}$)를 제시한다. 3차원 수리모형실험은 1983년 동해 중부 지진해일 발생 시 국내에서 가장 큰 피해를 입은 임원항을 대상으로 배후부지의 구조물과 인근 해안의 지형을 1/100으로 재현하여 실험에 임하였다. 입사파랑은 고립파(solitary wave)로 재현하였으며, 천수(shoaling)에 의한 파고변화를 측정하고 그에 따른 배후부지의 침수심, 구조물에 작용하는 파력을 측정하였다. 분석된 파력 산정계수(${\alpha}$)는 임원항 인근 해역 및 배후부지의 방재대책 수립을 위한 기초자료로 활용될 것으로 판단된다.