• 수산해양기술연구
• /
• 제30권3호
• /
• pp.142-149
• /
• 1994

In order to investigate the environmental properties of set net grounds located in the coastal waters of Yeosu. The current in the vicinity of set net grounds was observed by drogue and current meter in 1990 and 1992. The results obtained are summarized as follows: The direction of tidal current at the north enterance of Yeosu bay was southerly in ebb and northwesterly in flood without the distiction of the neap tide and the spring tide. In spring tide the maximum Velocity of the tidal current was 68 cm/sec in ebb and 66 cm/sec in flood. In neap tide the maximum velocity of the tidal current was 37 cm/sec in ebb and 35 cm/sec in flood. And so the direction of residual current was the south ward mainly and 21 cm/sec. The direction of tidal current at set net fishing grounds was southwesterly in ebb and westerly or northwesterly in flood. Regardless of the distinction of neap and spring. The maximum velocity of the current in spring tide was 50 cm/sec in ebb and 40 cm/sec in flood and that in neap was 28 cm/sec in ebb and 25 cm/sec in flood. In spring tide the speed vector along the major axis of semidiurnal tide component was three times as large as diurnal tide. In neap tide, however, the speed vector was about 50% less then that in spring tide, and the semidiurnal tide and diurnal tide were equal in the size of current ellipse and the direction of major axis. The sea area had a southwesterly residual current. 11 cm/sec in spring tide and 7 cm/sec in neap tide. According to the result of drogue tracking, the vicinity of set net fishing ground had a southerly residual current which formed in Yeosu Bay and a weak westerly residual current toward Dolsando from Namhedo. Therefore, set net fishing ground in coastal water of Yeosu was distributed in boundary of inner water which formed from Seamjin river and offshore water supplied from the vicinity of Sorido and Yochido.

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

• 대한원격탐사학회지
• /
• 제22권5호
• /
• pp.415-419
• /
• 2006

X-SAR images taken on the coastal waters of Hwanghe province in Korea during SIR-C/X-SAR campaign in April and October 1994 are analysed. The SAR images show the peculiar signatures like nail marks, curved long string, and vortex street patterns and they all seem to be produced by strong interactions between the topography in the coastal waters and tidal currents. The nail mark signatures are located at the same position of small scaled sand banks and the curved line patterns are almost identical to the outer boundary of large sand banks. Based on the tidal records, all the three images are taken at the almost same phase of tidal cycles, which are close to the low tide. It seems that bottom shapes are more strongly appeared on the SAR images when the tidal currents are slow. The front between two different current velocities caused by the flows along the steep boundaries of sandbanks is also the main factors imprinting the bottom features to the sea surface SAR images.

• 한국수산과학회지
• /
• 제30권6호
• /
• pp.1033-1043
• /
• 1997

In order to understand the generation mechanism of the Ulleung Eddy, we carried out a series of numerical experiments using the nonlinear 11/2 - layer model allowing the inflow of the Tsushima Current. According to our numerical results, the Ulleung Eddy was generated due to the inflow variations of the Tsushima Current. Its inflow through the Korea Strait was deflected to the east due to the Coriolis force and the nonlinear self advection. Thus, an anticyclonic motion was formed at the north of the Korea Strait. The inflow became a coastal boundary current, and finally flowed out model ocean through the eastern exit. When the speed of inflow decreased slowly, the eddy- like motion at the north of the Korea Strait changed into an enclosed anticyclonic eddy of about 200 km in diameter. The Ulleung Eddy became circular shape due to the nonlinear self advection, then changed into elliptical shape in meridional direction because of the blocking effect of the western boundary.

• 한국수산과학회지
• /
• 제37권2호
• /
• pp.148-158
• /
• 2004

In the adjacent seas of Cheju Island, the oceanographic conditions show low salinity surface waters starting in May. This water flows from the southeast part of the China Coastal Water, which flows southeastward along the Great Yangtze Sand Bank until April, with the help of southeasterly winds and flows from the adjacent sea off Cheju Island. In May, the Tsushima Warm Current and the low salinity surface water fluctuate in short and long-term periods as influenced by Yellow Sea Cold Water, which flows to the bottom layer at the western entrance of Cheju Strait. Temperature and salinity fronts in the northeastern sea area of U Island are formed in the boundary area between the Tsushima Warm Current, which expands towards Cheju Island from the southeastern sea area of Cheju Island and Hows out from the eastern entrance of the strait. Seasonally, additional oceanographic conditions, such as coastal counter-currents, which flow southward, appears within limited areas in the adjacent eastern and western seas of Cheju Island.

• 한국수산과학회지
• /
• 제16권2호
• /
• pp.51-58
• /
• 1983

한국 남서해 연안에서 여름에 발달했던 성층이 겨울철에 접어들면서 파괴되어 수직적으로 균일한 수온분포를 갖게 되는데 이러한 변화가 11월에 가장 활발하게 일어나는 것으로 나타났다. 이 변절기에 차고 염분이 낮은 연안 수괴가 대마난류와 접한 경계에 전선이 거의 수직으로 발달하며, 대마난류의 세력이 약한 제주해협의 중앙부를 제외하고는 수심 $70{\sim}90m$의 해역에서 수온전선과 염분전선의 위치는 일치하였다. 1980년 11월에 남해연안 중앙부에서 투하한 해류병이 주로 완도 근해에서 회수된 결과는 전선의 연안쪽에 있는 수괴가 서쪽으로 이동하는 남해연안반류의 존재를 뒷받침 해 주었다.

• 대한원격탐사학회지
• /
• 제33권6_2호
• /
• pp.1159-1169
• /
• 2017

1970년대 이후 다양한 인공위성 원격탐사 기술의 발달과 관측 자료의 축적으로 위성 원격탐사 자료와 연안 퇴적환경과의 관계 분석을 통한 연안환경 모니터링 연구가 진행되고 있다. 하지만, 여러 기관에서 제공 중인 연안주제도 생성에는 위성영상을 활용한 연안주제도 제작방법이 포함되어 있지 않다. 특히, 현재 국가에서 제공 중인 해양공간정보들은 조사주기가 길고 재가공 자료가 대부분이며 관측자료의 경우 일부영역에 대해서만 권역별로 조사하기 때문에 연안변화에 대한 모니터링이 어렵다. 본 연구에서는 원격탐사자료로 생성이 가능 한 연안주제도 중 연안경계도, 연안지형도, 연안표층퇴적상분포도 조사를 통해 연안지역의 공간화 및 대축척 급 국가연안주제도 제작의 선진화 방향에 대해 알아보았다.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
• /
• pp.740-743
• /
• 2006

We identify two distinct finer-scale frontal bands: 'Mainland China Coastal Front' (MCCF) and 'Kuroshio Front' (KF). The MCCF is along the 50-m isobath with large temperature gradient. The front is a boundary between the Mainland China Coastal Current and the offshore shelf waters. On the other hand, the KF is extending from the northeastern coast of Taiwan toward the northeast and into the shelf of south ECS. It forms a broad semicircle-shape and curving along 100-m isobath, it also deviates from eastward at around 26.5N-122E and leaves the shelf of ECS. This front should be the boundary between the Kuroshio water and the other shelf waters.

• 한국지리정보학회지
• /
• 제14권1호
• /
• pp.73-83
• /
• 2011

새만금 방조제 갑문의 개폐 상황은 새만금 인근 해역의 수질에 영향을 미치는 중요한 요소이다. 갑문의 개폐 정보는 새만금 방조제 인근 해역의 해상 탑에서 이루어지는 수질 및 유속 자료의 분석에 중요할 뿐만 아니라 해양 환경에 대한 수치 모의시 중요한 경계 조건이다. 본 연구에서는 기설치된 해상 관측 탑에 미니 노트북과 디지털카메라를 이용하여 자동무인영상 관측 시스템을 구축하고 촬영된 영상으로부터 갑문의 개폐상황을 자동으로 추출하였다. 특히 영상의 분산도 차이를 이용한 방법과 경계선 검출 기술을 동시에 활용한 결과 정확하게 갑문의 개폐 여부를 자동으로 확인할 수 있었다.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
• /
• 제3권1호
• /
• pp.57-73
• /
• 1999

Baroclinic hydraulic model experiments on the time-varying states of the flow pattern and water exchange in Sagami Bay were carried out based on quasi-steady state experiments on the flow pattern. For the model experiments, density changes as well as time changes in the volume transport of the upper layer were executed to investigate the flow response of the bay in the case of a sudden inflow of low density water and variable volume transport into the Sagami Bay. The results of the model experiments showed that when the volume transport was increased frontal eddies or frontal wave streamers from the Kuroshio Through Flow were transferred to the inner part of the bay along with cyclonic circulation in the bay. In addition, density boundary currents appeared and flowed along the eastern boundary of the bay. As the upper layer density decreased, frontal eddies, frontal streamers and coastal boundary density currents occurred and proceeded along the eastern boundary of the bay at a high speed.