• 한국측량학회지
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• 제33권3호
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• pp.181-192
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• 2015

Bathymetry change due to the 2011 Tohoku (M9.0) earthquake was investigated through satellite altimetry-derived free-air gravity anomalies (SAFAGA) and shipborne measurements. The earthquake occurred at the plate boundaries near the northeastern coast of Japan, where the oceanic plate subducts beneath the continental plate along deep-sea trench. Data analyzed in this study include SAFAGA from Scripps Institution of Oceanography (SIO), shipborne bathymetry (SB) from the U.S. National Geophysical Data Center (NGDC) and the Japan Agency for Marine-Earth-Science And Technology (JAMSTEC). To estimate the bathymetry change, a reference bathymetry before the earthquake was predicted by gravity-geologic method (GGM) and Smith & Sandwell’s (SAS) method. In comparison with the bathymetry models before the earthquake, GGM bathymetry model generated by a tuning density contrast of 17.04 g/cm³ by downward continuation method was selected because it shows better bathymetry in the short wavelength below about 6 km. From the results, remarkable bathymetry change of about ±50 m was found on the west side of the Japan Trench caused by the earthquake.

• International Journal of Ocean System Engineering
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• 제4권1호
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• pp.43-48
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• 2014

Varying bathymetry significantly affects on the wave propagation and motion response of floating body. Coupled-mode wave theory is adopted to describe the incident wave properly in varying region. The results of waves and motion response are compared to those from numerical wave tank, and the agreement is favorable. The sloped bottom is modeled and its effect on the floating body is discussed.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.496-499
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• 2004

컴퓨터와 다양한 software의 보급과 함께 흐름의 수치해석 분야는 급속한 발전을 보게 되었고 고도의 수치해법이나 복잡한 경계 처리 등을 통해 실제현상과 같은 흐름해석을 가능케 하고 있으며, 이러한 수치해석을 위해 정확한 Bathymetry는 필수적이다. 본 연구에서는 등 격자간격의 수심도 생성을 위하여 전자해도를 작업에 적합하게 수정하고 부족한 조간대의 수심자료는 보완하고, 파일형식에 따른 적절한 프로그램밍 언어를 통하여 해도상 지점들의 수심자료를 획득하고 내삽하여 기존에 사용되는 방법에 비하여 비교적 간단하고 해도의 정보를 정확하게 반영하는 Bathymetry를 생성하는 기법을 제안하였다.

• 한국해안·해양공학회논문집
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• 제28권5호
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• pp.265-276
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• 2016

2011년 3월 11일에 발생한 2011년 동일본(도호쿠) 지진해일은 한반도에 도달하여 많은 조위관측소에 기록되었다. 북동쪽 조위관측소 관측 자료에서 기존의 수치모의로 예측한 지진해일 도달시각보다 매우 이른 시간에 지진해일이 관측되는 지진해일 선행파가 관측되었다. Murotani et al.(2015)는 지형효과가 일본 및 러시아에서 관측된 지진해일 선행파와 관련 있음을 밝혔다. 본 연구에서는 지형효과를 고려한 지진해일 수치모의를 통해 우리나라에서 관측된 지진해일 선행파를 재현하였다. 이를 통하여 2011년 동일본 대지진과 같이 완만한 경사의 단층에서 발생한 지진에 의한 지진해일의 경우 지형효과를 고려하는 것이 지진해일 예측에 중요함을 알 수 있었다. 그러나 수치모의에 지형효과를 고려하기 위해서는 추가적인 연산 시간이 소요되므로 지진해일 통보 시스템에 적용하기 위해서는 충분한 검토가 필요하다.

• 자원환경지질
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• 제35권3호
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• pp.273-284
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• 2002

인공위성 레이더고도 측정값으로부터 유도된 중력이상으로턱터 남극 드레이크해협의 해저지형을 계산하기 위해 Gravity-Geologic Method(GGM)를 적용하였다. 총 6548개의 음항측심자료 중 2/3는 control depth로, 나머지는 결과 검증을 위한 check point 자료로 이용하였다. 효과적인 계산을 위해 해수와 해저지형의 밀도차이는 check point를 이용, 9.0 gm/㎤로 가정하였다. Control depth로부터 광역중력이상을 계산하였고, 이를 Sandwell & Smith(1997)의 중력이상으로부터 제거하여 해저지형의 기복에 의한 중력 효과를 계산하였으며, 이로부터 해저지형을 복원하였다. Selective Merging 기법을 개발하여 복원된 해저지형과 고주파 측심자료를 효과적으로 합성하였다. 복원된 해저지형은 한국해양연구원의 측심자료, GEODAS 및 전지구 모델 ETOPO5 결과와 각각 0.91, 0.92, 0.85의 상관계수를 갖으며, Selective Merging을 이용한 최종 결과는 GEODAS 및 Smith Sandwell(1997)의 결과와 각각 0.948 및 0.954의 상관관계 및 449.8, 441.3 m의 RMS 오차를 갖는다. GGM을 이용하여 계산된 해저지형은 측심이 충분히 이루어지지 않은 지역의 경우 전지구모델(ETOPO5)이나 자료의 양이 불충분한 음항측심에 의한 결과보다 우수한 것으로 나타났다.

• 한국환경과학회지
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• 제22권5호
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• pp.543-554
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• 2013

Acoustic Doppler Current Profilers (ADCPs) are increasingly popular in the river research and management communities being primarily used for estimation of stream flows. ADCPs capabilities, however, entail additional features that are not fully explored, such as morphological representation of river or reservoir bed based upon multi-beam depth measurements. In addition to flow velocity, ADCP measurements include river bathymetry information through the depth measurements acquired in individual 4 or 5 beams with a given oblique angle. Such sounding capability indicates that multi-beam ADCPs can be utilized as an efficient depth-sounder to be more capable than the conventional single-beam eco-sounders. The paper introduces the post-processing algorithms required to deal with raw ADCP bathymetry measurements including the following aspects: a) correcting the individual beam depths for tilt (pitch and roll); b) filtering outliers using SMART filters; d) transforming the corrected depths into geographical coordinates by UTM conversion; and, e) tag the beam detecting locations with the concurrent GPS information; f) spatial representation in a GIS package. The developed algorithms are applied for the ADCP bathymetric dataset acquired from Han-Cheon in Jeju Island to validate themselves applicability.

• 자원환경지질
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• 제29권5호
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• pp.575-587
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• 1996

The purpose of this study is to develop geostatistical methods for selection of prospective areas of polymetallic nodule deposits in KODOS (Korea Deep Ocean Study) area of the North-East Pacific Ocean. In this study $110{\times}165$ grid system was used, and each node represents the center of an estimated block of $1km{\times}1km$. The ordinary kriging was applied to SeaBeam2000 data in order to evaluate the bathymetry. A structural analysis (variogram) of the bathymetry data was carried out for constructing digital terrain model (DTM) and the maximum slopes of the bathymetry were calculated by DTM data. The above method can be used to solve the problem that is resulted from the lack of theory of a change of support model for the maximum slope of the bathymetry. The ordinary kriging and the indicator kriging were used to evaluate the nodule abundance, and the different two kriging methods were compared to evaluate the accuracy for the estimation of the nodule abundance. It has been shown that indicator kriging was better estimation tool than the ordinary kriging. The overlay map is presented for the selection of potentially minable sites by combining the two indicator maps of the nodule abundance and the maximum slope of bathymetry. This overlay map could be utilized to establish follow-up survey and to investigate the potentially minable sites in the KODOS area.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.664-669
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• 2002

Intertidal zone (tidal flat) is a place which is sometimes dry and sometimes wet depending on the tidal rhythm. Direct measurement of topography in the intertidal zone is very difficult to be achieved. The interface between wet and dry parts in the tidal flat, which can be identified from near infrared band of satellite image, is a 'depth contour' which corresponds to the sea level at the time of satellite pass. Aquisition of topography data in tidal flat is possible by combining various techniques such as (1) identification of the interface between wet and dry parts, (2) GCP correction of satellite image, and (3) realtime prediction of sea level elevation at the time of satellite pass. The algorithm was successfully applied in obtaining topography (bathymetry) data in the intertidal zone of Asan Bay in the west coast of Korea from 26 satellite images. The method is expected to be very efficient in making bathymetry data base in the western and southern parts of Korea where tidal flats are well developed in wide regions.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.432-434
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• 2003

The main objective of this research is to utilize the parallel Fuzzy arithmetic for constructing ocean bathymetry from polarized remote sensing data such as TOPSAR image. In doing so, the parallel library for Fuzzy arithmetic has been developed. Three- dimensional surface modeling consisted of Volettra model, non-linear model which construct a global topological structure between the data points, used to support an approximation of real surface. The output of the parallel library was a digital terrain model for bathymetry along the coastal waters of Kuala Terengganu Malaysia. This paper describes the principles behind the Fuzzy algorithm, indicates for what type of application it might be useful, notes on the accuracy and gives an example of an application.

• 대한원격탐사학회지
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• 제25권6호
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• pp.501-505
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• 2009

Quasi-linear bright features persistently appeared on ENVISAT ASAR images as well as X-SAR images along the tidal channels in Gyung-Gi Bay, Korea during the ebb tides. These features are induced by spatial backscatter variations caused by surface convergence (divergence) through the interaction between tidal currents and bathymetry. In order to validate this mechanism, a numerical tidal model simulation is performed on the realistic bathymetry with the tidal boundary conditions. The tide model reproduces the current convergence zone along the tidal channel during the ebb tides, which exactly coincides with the location of bright line features on SAR images.