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Lee D.-K.,Pusan National University | Kwon J.-I.,Korea Advanced Institute of Science and Technology | Kwon J.-I.,China Korea Joint Ocean Research Center | Son S.H.,Colorado State University
Acta Oceanologica Sinica | Year: 2015

During the summer in the Yellow Sea and East China Sea, the resuspension of the bottom sediment is obstructed by strong stratification and, as a result, the concentration of total suspended sediment (TSS) can be used as an excellent tracer for Changjiang Diluted Water (CDW). To analyze the spatial and temporal variations of the CDW distribution, the monthly mean TSS from Moderate Resolution Imaging Spectroradiometer (MODIS) ocean color data are constructed and are converted to salinity using the relationship between salinity observed from AQUARIUS and TSS. The process produces the detailed horizontal distribution of salinity with very high resolution (1 km). From monthly mean salinity map from 2002 to 2012 in July and August, the expansion patterns of CDW are analyzed. The southerly wind in July and southeasterly wind in August transport the CDW eastward and northeastward, respectively. It is found that the yearly variation of the expansion of CDW toward the southern sea area of Korea is mostly due to the variation of southerly wind and the fluctuations of fresh water discharge into the Changjiang estuary show relatively little impact on the eastward extend of CDW. When 11-year mean (from 2002 to 2012) salinity map in August is compared with World Ocean Atlas 2013, it is revealed that wind in August strengthened six times from 1994 and it causes the expansion of CDW extended 150 km further eastward. © 2015, The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg. Source

Choi J.,Korea Advanced Institute of Science and Technology | Jun K.,Korea Advanced Institute of Science and Technology | Choi Y.,Korea Advanced Institute of Science and Technology | Cho K.,Korea Polar Research Institute | And 3 more authors.
Acta Oceanologica Sinica | Year: 2015

The Maenggol Channel and Uldolmok Strait, located on the south-west coast of Korea, have notably strong and complex currents due to tidal effects and to local geological factors. In these areas, electric power has been generated using strong tidal currents, the speed of which is more than 3 m/s during spring tides. The region also provides a shortcut for navigation. These tidal conditions are therefore sometimes useful, but may also cause terrible accidents or severe economic damage, in the absence of accurate information regarding ocean conditions. In April 2014, the passenger ferry MV Sewol capsized in the Maenggol Channel, with 295 passengers killed and 9 still missing. While this was unquestionably a man-made disaster, strong currents were one of the contributing causes. It was also difficult to conduct scuba diving rescue operations given strong current speeds, and accurate prediction of the time when the tide would turn was thus critically needed. In this research, we used the high-resolution coastal circulation forecasting system of KOOS (Korea Operational Oceanographic System) for analysis and simulation of strong tidal currents in such areas with many small islands, using measurements and modeling from this research area. For accurate prediction of tidal currents, small grid size-modeling was needed, and in this study, we identified a suitable grid size that offers efficiency as well as accuracy. © 2015, The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg. Source

Yan G.,Xuchang University | Rai L.,Shandong University of Science and Technology | Fen X.J.,China Korea Joint Ocean Research Center
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

This paper proposes a novel recursive algorithm, towards finding all routing paths in an unidirectional flow- network. The algorithm is recursive, so it provides a flexible approach comparing to iterative methods. Initially, all the paths from source to destinations are identified and represented in a two-dimensional matrix. The recursive algorithm uses the concept of blanking patterns, by identifying definite patterns of combinations of rows and columns in the two-dimensional matrix. © 2013 SPIE. Source

Park K.-S.,Coastal Disaster Research Center | Heo K.-Y.,Coastal Disaster Research Center | Jun K.,Coastal Disaster Research Center | Kwon J.-I.,China Korea Joint Ocean Research Center | And 13 more authors.
Ocean Science Journal | Year: 2015

The Korea Operational Oceanographic System (KOOS) was developed at the Korea Institute of Ocean Science and Technology (KIOST) to produce real-time forecasting and simulation of interdisciplinary multi-scale oceanic fields. This offers valuable information to better mitigate coastal disasters, such as oil spills and other marine accidents, and provides the necessary ocean predictions to support the marine activities of government agencies, marine industries, and public users. The KOOS became operational in March 2012, and consists of several operational modules and realtime observations, including satellite remote sensing, coastal remote monitoring stations using high-frequency radar, and ocean observatories. The basic forecasting system includes weather, regional and high-resolution coastal circulation and wave prediction models; the practical application system includes storm surges, oil spills, and search and rescue prediction models. An integrated maritime port prediction system and data information and skill assessment systems are also part of the KOOS. In this work, the performance of the numerical models was evaluated by the skill assessment systems. From the monthly and yearly skill assessments, the models showed reasonable skill in predicting atmospheric and oceanic states except for the regional ocean circulation models. The ongoing development and improvement of the KOOS includes improvement of the model skills through the upgrade of the satellite-based sea surface temperature algorithm, the enhancement of the ocean monitoring ability, the upgrade of the forecasting models for higher spatial resolutions and the application of data assimilation techniques improved with the feedback from the skill assessment report. © 2015, Korea Ocean Research & Development Institute (KORDI) and the Korean Society of Oceanography (KSO) and Springer Science+Business Media Dordrecht. Source

Jo Y.-H.,Pusan National University | Sha J.,University of Delaware | Kwon J.-I.,Korea Institute of Science and Technology | Kwon J.-I.,China Korea Joint Ocean Research Center | And 2 more authors.
Acta Oceanologica Sinica | Year: 2015

Mapping shoreline changes along coastal regions is critically important in monitoring continuously rising sea surface heights due to climate change and frequent severe storms. Thus, it is especially important if the region has very high tidal ranges over very gentle tidal flats, which is a very vulnerable region. Although the various remote sensing platforms can be used to map shoreline changes, the spatial and temporal resolutions are not enough to obtain it for a short time. Accordingly, in this study we introduce the newly developed low altitude Helikite remote sensing platform to achieve much better resolutions of shorelines and a bathymetry. The Helikite stands for Helium balloon and Kite, which is a kind of aerial platform that uses the advantages of both a Helium balloon and a kite. Field experiments were conducted in the Jaebu Island, off the coast of the west Korean Peninsula in January 29, 2011. In order to extract shorelines from the consecutive images taken by the low altitude Helikite remote sensing platform, active contours without edges (ACWE) is used. Edges or boundaries exist primarily on places between one type of objective and the other. Since the hydrodynamic pressure has an effect everywhere, the locations of the waterlines can be the isobath lines. We could map several waterlines, which would enable us to complete a local bathymetry map ranges from 35 to 60 cm depth. The error resulting from applying ACWE algorithm to the imagery to determine the waterline is approximately less than 1 m. Therefore, it is very unique way to obtain such high resolutions of bathymetry with high accuracy for the regions of extremely high tidal ranges for a short time. © 2015, The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg. Source

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