• 한국측량학회지
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• 제25권6_1호
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• pp.517-528
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• 2007

Extraction of the coastal boundary is important because the boundary serves as a reference in the demarcation of maritime zones such as territorial sea, contiguous zone, and exclusive economic zone. Accurate nautical charts also depend on well established, accurate, consistent, and current coastline delineation. However, to identify the precise location of the coastal boundary is a difficult task due to tidal and wave motions. This paper presents an efficient way to extract coastlines by applying digital image processing techniques to Synthetic Aperture Radar (SAR) imagery. Over the past few years, satellite-based SAR and high resolution airborne SAR images have become available, and SAR has been evaluated as a new mapping technology. Using remotely sensed data gives benefits in several aspects, especially SAR is largely unaffected by weather constraints, is operational at night time over a large area, and provides high contrast between water and land areas. Various image processing techniques including region growing, texture-based image segmentation, local entropy method, and refinement with image pyramid were implemented to extract the coastline in this study. Finally, the results were compared with existing coastline data derived from aerial photographs.

• 한국해안해양공학회지
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• 제7권2호
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• pp.141-147
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• 1995

파랑변형을 계산하는 여러가지 수치모형이 제안되어 있다. 그 중에서도 선유량과 수면변위로 나타내는 시간의존 완경사방정식을 이용한 수치모형이 반사파가 존재하는 파랑장에서는 지금까지 널리 사용되고 있다. 이 경우 경사지게 입사하는 파에 대하여 파랑장의 외해경계 뿐만 아니라 측방경계 중, 하나는 입사경계로 처리되어야 한다. 본 연구에서는 측방입사경계 처리 방법으로서, Maruyama와 Kajima(1985), Copeland(1985), 그리고 Ohnaka와 Watanabe(1987)의 방법을 고려한 후, 파고비, 파향 그리고 위상의 계산결과치로 각 방법들의 특성을 비교 분석하였다. 그 결과 Ohnaka와 Watanabe(1987)의 방법이 일반적인 해저경사를 가진 파랑장에서 가장 적절한 측방입사경계 처리 방법인 것을 알 수 있었다.

• Wind and Structures
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• 제17권4호
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• pp.419-433
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• 2013

This paper investigates the vertical profiles of horizontal mean wind speed and direction based on the synchronized measurements from a Doppler radar profiler and an anemometer during 16 tropical cyclones at a coastal site in Hong Kong. The speed profiles with both open sea and hilly exposures were found to follow the log-law below a height of 500 m. Above this height, there was an additional wind speed shear in the profile for hilly upwind terrain. The fitting parameters with both the power-law and the log-law varied with wind strength. The direction profiles were also sensitive to local terrain setups and surrounding topographic features. For a uniform open sea terrain, wind direction veered logarithmically with height from the surface level up to the free atmospheric altitude of about 1200 m. The accumulated veering angle within the whole boundary layer was observed to be $30^{\circ}$. Mean wind direction under other terrain conditions also increased logarithmically with height above 500 m with a trend of rougher exposures corresponding to lager veering angles. A number of empirical parameters for engineering applications were presented, including the speed adjustment factors, power exponents of speed profiles, and veering angle, etc. The objective of this study aims to provide useful information on boundary layer wind characteristics for wind-resistant design of high-rise structures in coastal areas.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 1993년도 가을 학술발표회 초록집
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• pp.17-17
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• 1993

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 1994년도 봄 특별 환경 심포지움 및 학술발표회 초록집
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• pp.82-82
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• 1994

• 한국항해항만학회지
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• 제36권7호
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• pp.561-569
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• 2012

In this paper, the boundary element method is applied to solve the diffraction of waves by multiple vertical cylinders under the assumption of linear wave theory. A numerical analysis by boundary element method is based on Green's theorem and introduced to an integral equation for the fluid velocity potential around the cylinders. The numerical results obtained in this study are compared with the experimental data and the results of the theory using multiple scattering techniques. The comparisons show strong agreement. This numerical analysis method developed by using boundary element method could be used broadly for the design of various offshore structures to be constructed in coastal zones in the future.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1995년도 정기학술강연회 발표논문 초록집
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• pp.16-19
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• 1995

Effects of the changes in bottom topography and non-linearity of the western boundary current on the separation position of the Tsushima Warm Current(TWC) are investigated using a primitive equation model in a simplified model domain which consists of a deep ocean, a continental shelf and a marginal sea(Fig. 1). (omitted)

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1996년도 정기학술강연회 발표논문 초록집
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• pp.14-14
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• 1996

In order to understand the tidal hydrodynamics of the Yellow Sea and Parts of the East China Sea, we have developed a three-dimensional, fine resolution, nonlinear, harmonic finite element model. Major four tidal constituents, M$_2$, S$_2$, K$_1$ and O$_1$ are used as forcing along the open boundary. Due to the shallowness of the region, tidal results are strongly affected by the bottom roughness coefficients, especially for the quadratic form. (omitted)

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1997년도 정기학술강연회 발표논문 초록집 Annual Meeting of Korean Society of Coastal and Ocean Engineers
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• pp.131-134
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• 1997

항만을 새로 건설할 때에는 여러 가지 고려해야 할 중요한 사항이 있다. 이 가운데 항내정온도는 가장 기본적이며 필수적으로 고려해야 할 사항이다. 항의 입구에서 전파되어 오는 입사파로 인해 발생하는 항만 내부의 동요가 너무 크면 하역 작업이 어려워지고 정박되어 있는 선박이 파손될 우려가 있다. 따라서, 항내의 동요에 대하여 가능한 한 정확하게 예측하여 항내 동요가 가장 적은 즉 항내측이 가장 정온한 항만의 형상을 선택해야 한다. (중략)

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1992년도 정기학술강연회 발표논문 초록집
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• pp.140-145
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• 1992

The design of large offshore structures and their operations depend critically upon the wave-induced loads and motions. Thus, over the last two decades, substantial efforts have been devoted to the development of various principles and methods which can provide these predictions in a reliable and efficient manner.(omitted)