• 제목/요약/키워드: Hydrography

검색결과 53건 처리시간 0.024초

A Numerical Experiment on the Dispersion of the Changjiang River Plume

  • Bang, In-Kweon;Lie, Heung-Jae
    • Journal of the korean society of oceanography
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    • 제34권4호
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    • pp.185-199
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    • 1999
  • With a realistic geography and topography the Princeton Ocean Model is used to study the effects of topography, wind and time-varying Chanajiang (Yangtze) River discharge on the dispersion of the Chanaiiang River plume in the Yellow and East China Seas. The topographic feature of deepening offshore suppresses the offshore expansion of the discharged low salinity water while spreading along the coast is not hindered. Also the spreading of the Chanajiang River plume is very sensitive to wind conditions and the southerly wind is most responsible for the eastward expansion toward the Cheju Island. It is also shown that the influence of the Chanajiang River Diluted Water on the hydrography and circulation of the Yellow Sea including the South Sea of Korea is substantial even in the absence of tide, wind and current.

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2000년 여름 영산강 하구의 해수 특성과 순환 (Hydrography and Circulation in the Youngsan River Estuary in Summer, 2000)

  • 조양기;조철;선연종;박경양;박래환
    • 한국해양학회지:바다
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    • 제6권4호
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    • pp.218-224
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    • 2001
  • 영산강 하구 내 해수 유동의 시공간적 변화를 이해하기 위하여 해수의 물성과 유속을 종합적으로 관측하였다. 수문 개방으로 많은 양의 담수 유입이 있었던 다음 날인 2000년 7월 27일부터 28일까지 25시간 동안 영산강 하구에서 관측을 실시하였다. 하구 내 12개 정점에서 27일 저조, 28일 고조와 저조때 각각 CTD 관측을 하였고, 하구 내한 정점에서 25시간 동안 수심별 수온과 유속 관측을 실시하였다. 유속은 Acoustic Doppler Profiler(1.5 MHz)를 이용하여 수직적으로 1m 간격으로 측정하였다. 동시에 하구 내 두 정점에서 TGPS 부이를 띄워 표층 해수 유동을 관측하였다. 관측기간은 소조에 해당되며, 조차는 약 4 m, 최대 조류는 약 12 cm/sec였다. 25시간 동안 관측된 유속은대부분의 수층에서 하구를 따라 동서방향으로 반일주조형태의 조류 특성을 잘 보여준다. 그러나 표층의 경우 바람에 의해 유속의 방향이 크게 영향을 받는 것으로 나타났다. 표층 2m이내에 존재하는 22 psu 이하의 저염수는, 관측 초기 남풍에 의해 북쪽 해안선을 따라 관측되었다. 바람의 방향이 동풍으로 바뀜에 따라 표층수는 외해로 흘러나가, 이튿날 관측시에는 하구 내에서 22 psu 이하의 저염수가 발견되지 않았다 유속과 수괴 특성을 분석한 결과일반적인 하구의 수직구조와 달리 본 해역은 수직적으로 네 개의 층으로 나눌 수 있었다. 담수 기원으로 생각되는 표층과 중층의 해수는 25시간 평균 유속이 외해를 향하며, 상층과 하층의 평균 유속은 강쪽을 향하고 있다 이러한 수직 구조는 하구언으로부터 강물의 유입이 불규칙적으로 이루어지기 때문에 발생한 현상이라고 생각된다.

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한국 황해 백령도 주변해역 후 제4기 퇴적작용 (Late Quaternary Sedimentation in the Yellow Sea off Baegryeong Island, Korea)

  • 조민희;이은일;유학렬;강년건;유동근
    • 지구물리와물리탐사
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    • 제16권3호
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    • pp.145-153
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    • 2013
  • 황해 백령도 주변해역에 분포하는 해저면 연계퇴적층의 음향상 연구를 위해 고해상 탄성파 탐사자료를 분석하였다. 해저지형 및 내부 음향상 특징에 의하면 연구지역에 분포하는 천부퇴적층은 총 7개의 음향상으로 구분된다. 내부 반사면이 약간 혹은 양호하게 발달하거나 내부반사면을 전혀 수반하지 않는 평탄한 해저면(음향상 1-1, 1-2)은 연구지역의 남쪽에 주로 분포한다. 파형의 표면구조를 수반하는 평탄한 해저면(음향상 1-3)은 중부해역에 발달한다. 평탄한 해저면 혹은 파형의 표면구조를 수반하는 마운드 형태의 해저면 특징(음향상 2-1, 2-2, 2-3)은 중부해역에 분포한다. 내부 반사면이 발달하지 않고 불규칙한 침식흔적을 갖는 해저면(음향상 3-1)은 조사해역의 북부해역인 백령도 외해쪽에 주로 존재한다. 음향상의 분포 및 퇴적물 특성에 의하면 연구지역의 퇴적환경은 뚜렷한 3 지역으로 구분되는 바 (1) 강한 조류의 영향으로 심한 침식작용이 진행되고 있는 북쪽지역, (2) 해수면 상승과 연계된 조류의 영향으로 형성된 사퇴가 분포하는 중부해역, (3) 박층의 해침 사질층이 분포하고 있는 남부해역 등으로 구성된다. 연구지역에 분포하는 7 음향상을 포함하는 이와 같은 퇴적층은 홀로세 해침동안 해수면 상승 및 강한 조류와 연계된 퇴적작용을 반영한다.

Interactive Navigational Structures

  • Czaplewski, Krzysztof;Wisniewski, Zbigniew
    • 한국항해항만학회:학술대회논문집
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    • 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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    • pp.495-500
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    • 2006
  • Satellite systems for objects positioning appeared indispensable for performing basic tasks of maritime navigation. Navigation, understood as safe and effective conducting a vehicle from one point to another, within a specific physical-geographical environment. [Kopacz, $Urba{\acute{n}}ski$, 1998]. However, the systems have not solved the problem of accessibility to reliable and highly accurate information about a position of an object, especially if surveyed toward on-shore navigational signs or in sea depth. And it's of considerable significance for many navigational tasks, carried out within the frameworks of special works performance and submarine navigation. In addition, positioning precisely the objects other than vessels, while executing hydrographical works, is not always possible with a use of any satellite system. Difficulties with GPS application show up also while positioning such off-lying dangers as wrecks, underwater and aquatic rocks also other naturaland artificial obstacles. It is caused by impossibility of surveyors approaching directly any such object while its positioning. Moreover, determination of vessels positions mutually (mutual geometrical relations) by teams carrying out one common tasks at sea, demands applying the navigational techniques other than the satellite ones. Vessels'staying precisely on specified positions is of special importance in, among the others, the cases as follows: - surveying vessels while carrying out bathymetric works, wire dragging; - special tasks watercraft in course of carrying out scientific research, sea bottom exploration etc. The problems are essential for maritime economy and the Country defence readiness. Resolving them requires applying not only the satellite navigation methods, but also the terrestrial ones. The condition for implementation of the geo-navigation methods is at present the methods development both: in aspects of their techniques and technologies as well as survey data evaluation. Now, the classical geo-navigation comprises procedures, which meet out-of-date accuracy standards. To enable meeting the present-day requirements, the methods should refer to well-recognised and still developed methods of contemporary geodesy. Moreover, in a time of computerization and automation of calculating, it is feasible to create also such software, which could be applied in the integrated navigational systems, allowing carrying out navigation, provided with combinatory systems as well as with the new positioning methods. Whereas, as regards data evaluation, there should be applied the most advanced achievements in that subject; first of all the newest, although theoretically well-recognised estimation methods, including estimation [Hampel et al. 1986; $Wi{\acute{s}}niewski$ 2005; Yang 1997; Yang et al. 1999]. Such approach to the problem consisting in positioning a vehicle in motion and solid objects under observation enables an opportunity of creating dynamic and interactive navigational structures. The main subject of the theoretical suggested in this paper is the Interactive Navigational Structure. In this paper, the Structure will stand for the existing navigational signs systems, any observed solid objects and also vehicles, carrying out navigation (submarines inclusive), which, owing to mutual dependencies, (geometrical and physical) allow to determine coordinates of this new Structure's elements and to correct the already known coordinates of other elements.

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무인 잠수정의 퍼지제어 (Fuzzy Control of Underwater Robotic Vehicles)

  • 이원창;강근택
    • 동력기계공학회지
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    • 제2권2호
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    • pp.47-54
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    • 1998
  • Underwater robotic vehicles(URVs) have been an important tool for various underwater tasks such as pipe-lining, data collection, hydrography mapping, construction, maintenance and repairing of undersea equipment, etc because they have greater speed, endurance, depth capability, and safety than human divers. As the use of such vehicles increases, the vehicle control system is one of the most critical subsystems to increase autonomy of the vehicle. The vehicle dynamics are nonlinear and their hydrodynamic coefficients are often difficult to estimate accurately. It is desirable to have an intelligent vehicle control system because the fixed-parameter linear controller such as PID may not be able to handle these changes promptly and result in poor performance. In this paper we described and analyzed a new type of fuzzy model-based controller which is designed for underwater robotic vehicles and based on Takagi-Sugeno-Kang(TSK) fuzzy model. The proposed fuzzy controller: 1) is a nonlinear controller, but a linear state feedback controller in the consequent of each local fuzzy control rule; 2) can guarantee the stability of the closed-loop fuzzy system; 3) is relatively easy to implement. Its good performance as well as its robustness to parameter changes will be shown and compared with those of the PID controller by simulation.

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Evaluation of S-100 ECDIS Based on S-10X Digital Maritime Safety Information

  • CHOI, HyunSoo;OH, SeWoong;KANG, DongWoo;Yoon, MyongO
    • 한국항해항만학회지
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    • 제44권5호
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    • pp.375-381
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    • 2020
  • The IMO has established a regulation for the ECDIS installation on ships based on the IHO S-57 standards. The ECDIS supports sailors in achieving a safe voyage by using ENCs and monitoring the information of their ship. However, the S-57 standards were developed as edition 3.1 and prohibited revision for more than 20 years. So, the IHO developed a new standard as S-100 into the hydrography and maritime field instead of updating the S-57 to edition 4.0. In this study, the new S-100 ECDIS was developed and verified with ENCs and the digital maritime safety information by using a ship steering simulator and by conducting an on-board sea-trial test. It evaluated the impact on ship operations if the next-generation navigation support system is introduced. Based on this research, the S-100 ECDIS will generate improvements such as safe voyages by providing various of real-time safety information and up-to-date data to ship and sailors.

Monthly Variation of Water Mass Distribution and Current in the Cheju Strait

  • Pang, Ig-Chan;Hong, Chang-Su;Chang, Kyung-Il;Lee, Jae-Chul;Klm, Jun-Teck
    • Journal of the korean society of oceanography
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    • 제38권3호
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    • pp.87-100
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    • 2003
  • The monthly observations of hydrography in the Cheju Strait from September 1995 to June 1998 show that the Cheju Strait is occupied mostly by Tsushima Current Water in winter and coastal waters in summer. In summer, the Yangtze Coastal Water appears in the upper layer and cold water in the lower layer. Especially, the Yellow Sea Bottom Cold Water appears in August 1997, and the clockwise flow of warm water along the northwestern coasts of Cheju Island is disturbed by an eastward expansion of the cold water from the northwest. The cold water expansion seems to be partly associated with strong southeasterly winds. Current measurements in the Cheju Strait suggest that there exists steady eastward barotropic component of about 5 cm/sec, which corresponds to 0.2 Sv barotropic transport in the Cheju Strait. Geostropic transport (baroclinic component) ranges from 0.1 Sv in winter to 0.4 Sv in summer. By adding the barotrophic component of 0.2 Sv, the total transport varies from 0.3 Sv to 0.6 Sv, which is consistent with previous estimations. The transport increase in summer seems to be caused by the expansion of coastal water to the Cheju Strait.

부산권역 어항의 도시형 어항 개발 가능성 평가 (Estimating the Development Potential of Urban Fishing Ports in the Region of Busan, Korea)

  • 김영표;유창일;윤한삼;김헌태
    • 수산해양교육연구
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    • 제19권3호
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    • pp.355-365
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    • 2007
  • This study examined the essential elements of urban fishing ports in the region of Busan in terms of the hydrography, geomorphology, and urban functions of each fishing port and then estimated their development potential. The results were as follows: (1) The ports in the eastern and central parts of the Busan region, used mostly for fishing, were open or quasi-open type ports with ${\Omega}>0.8$, while those of the western part tended to show the reverse. (2) Of the 51 fishing ports, 37.3% were located on land inside the coastline, and structures such as breakwaters had been constructed on both sides of the entrance. Of the total, 47.1% were small fishing ports with water depths of 0~1 m. (3) In the Busan region, 39.2% were urban fishing ports, including Daebyeon and Dadaepo, and 60.8% were non-urban fishing ports.

이중 주파수 에코 사운드 시스템을 이용한 부니층 두께 조사 (Estimation of the thickness of floating silty clay sediment using dual frequency single beam echo sound system)

  • 하희상
    • 지구물리
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    • 제5권3호
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    • pp.219-231
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    • 2002
  • 일반적으로 수심측량은 항측, 항해 분야에서 해저면의 지형을 조사하기 위해 사용되어왔다. 이 논문에서는 주파수에 따라 해저면에 대한 음파의 침투심도가 다르다는 사실을 이용하여 같은 지역에 대하여 고주파(200 KHz)와 저주파(33 KHz) 두개의 시스템을 이용하여 수심을 측정한 후 두 결과의 차이로부터 부니층의 두께를 조사하고자 하였다. 이 층의 물리적인 특성을 분석하기 위하여 RI 방사능 밀도 검층을 수행하여 비교하였다. 연구 대상지역은 광양만 투기장 건설 예정지역으로 부니층의 체적을 계산하여 적정한 투기장 규모를 설계하는데 이용되었다. 향후 항만 지역 및 호수 수계에 대한 정기적인 조사를 통하여 부니층 두께 또는 시간에 따른 퇴적 패턴에 대한 분석도 가능할 것으로 판단된다.

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HEC-RAS 모델을 이용한 신천 시험유역의 하도 특성연구 (Channel Characteristics of Sincheon Experimental Catchment using HEC - RAS model)

  • 박병기;이명구;홍창수;이재관;이영준;최중대
    • 한국환경과학회지
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    • 제25권1호
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    • pp.41-56
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    • 2016
  • In recent localized heavy rainfalls have been arising from abnormal climate change. People are concerning about damages with increasing the frequency of flooding. Therefore, we need to understand river hydraulic characteristics and management to reduce damage from flooding. To study hydraulic characterization of Sincheon experimental catchment HEC-RAS (Hydrologic Engineering Center River Analysis System) model which provided by U.S Army Corps of Engineers (USACE) was applied. This study analyzed and compared water level the frequency flood for 100 years and 200 years by clark unit Hydrography. The change of the water level of Daejeon bridge, Sincheon bridge and Singi bridge showed increased for all conditions. The flow rate for the Daejeon bridge and the Sincheon bridge showed an increase, but the Sinki bridge showed a decreasing flow rate overally, except for 1hour-100 years. The verification result showed that the model was able to simulate the water level with 0.4709 coefficient of determination and error ration ranging from 1 to 3%.