• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.1
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• pp.25-34
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• 2017

The concentric dual-buoy Wave Energy Converter (WEC), which consists of external buoy (hallow-cylinder) with toroidal appendage and cylindrical internal buoy within the moon-pool is suggested in this research and its performance in various wave conditions is studied. The Linear Electric Generator (LEG), consisting of a permanent magnet and coils, is used as a direct Power Take-Off (PTO) system. To maximize the electrical energy extracted from the PTO system, the relative heave motions between the dual buoys must be highly amplified by the multiple resonance phenomena of dual-buoy and internal-fluid motions. The high-performance range can be widened by distributing those natural frequencies with respect to the peak frequency of the wave spectrum. The performance of the newly developed dual-buoy WEC was measured throughout the systematic 1:5.95-model test in regular and irregular waves conducted in a wave tank at Seoul National University. The model-test results are also validated by an independently developed numerical method.

• Korean Journal of Remote Sensing
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• v.38 no.4
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• pp.355-364
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• 2022

In this study a tendency of abnormal sea surface temperature (SST) occurrence in the seas around South Korea is analyzed from daily SST data from satellite and 14 buoys from August 2020 to July 2021. As thresholds 28℃ and 4℃ are used to determine marine heatwaves(MHWs) and abnormal low water temperature (ALWT), respectively, because those values are adopted by the National Institute of Fisheries Science for the breaking news of abnormal temperature. In order to calculate frequency of abnormal SST occurrence spatially by using satellite SST, research area was divided into six areas of coast and three open seas. ALWT dominantly appeared over a wide area (7,745 km²) in Gyeonggi Bay for total 94 days and it was also confirmed from buoy temperature showing an occurrence number of 47 days. MHWs tended to be high in frequency in the coastal areas of Chungcheongdo and Jeollabukdo and the south coastal areas while in case of buoy temperature Jupo was the place of high frequency (32 days). This difference was supposed to be due to the low accuracy of satellite SST at the coasts. MHWs are also dominant in offshore waters around Korean Peninsula. Although detecting abnormal SST by using satellite SST has advantage of understanding occurrence from a spatial point of view, we also need to perform detection using buoys to increase detection accuracy along the coast.

• Proceedings of the KSRS Conference
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• v.1
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• pp.146-149
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• 2006

Marine surface winds observed by two microwave sensors, SeaWinds and Advanced Microwave Scanning Radiometer (AMSR), on the Advanced Earth Observing Satellite-II (ADEOS-II) are evaluated by comparison with off-shore moored buoy observations. The wind speed and direction observed by SeaWinds are in good agreement with buoy data with root-mean-squared (rms) differences of approximately 1 m $s^{-1}$ and $20^{\circ}$, respectively. No systematic biases depending on wind speed or cross-track wind vector cell location are discernible. The effects of oceanographic and atmospheric environments on the scatterometry are negligible. The wind speed observed by AMSR also exhibited reasonable agreement with the buoy data in general with rms difference of 1.2 m $s^{-1}$. Systematic bias which was observed in earlier versions of the AMSR winds has been removed by algorithm refinements. Intercomparison of wind speeds globally observed by SeaWinds and AMSR on the same orbits also shows good agreements. Global wind speed histograms of the SeaWinds data and European Centre for Medium-range Weather Forecasts (ECMWF) analyses agree precisely with each other, while that of the AMSR wind shows slight deviation from them.

• Proceedings of the KSRS Conference
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• v.1
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• pp.394-397
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• 2006

Gridded products of surface wind/wind-stress over the world ocean have been constructed by using satellite scatterometer as the Japanese Ocean Flux data sets with Use of Remote-sensing Observation (J-OFURO) data. Our previous validation study in the tropical Pacific using TAO/Triton and NDBC buoys revealed high reliability of our products. In this study, the Kuroshio Extension Observatory (KEO) buoy data are used for validation of other gridded wind-stress products including the NCEP-1 and 2 in the western North Pacific region where there have been few in-situ data. Results reveal that our J-OFURO product has almost zero mean difference and smallest root-mean-square (RMS) difference, while the NCEP-1 and 2 ones significantly positive biases and relatively high RMS difference. Intercomparison between the J-OFURO and NCEP products in a wide region of the North Pacific covered by the westerly winds exhibits that the NCEPs have larger magnitudes in the wind stress than the J-OFURO's, suggesting overestimation of the NCEPs.

• New & Renewable Energy
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• v.7 no.1
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• pp.15-21
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• 2011

In recent years, many countries have been endeavoring to exploit the offshore wind energy in terms of overcoming the limitations of on-land wind energy. Considering that mountains cover 70 percent of the Korean Peninsula and arable plains for wind energy are negligibly small, Korean government aggressively drives the offshore wind development of the Korean Peninsula. As part of preliminary investigation of offshore wind resources, KEPCO-RI (Korea Electric Power Corporation-Research Institute) has been analyzing marine buoy datasets measured at 5 positions over the period of 12 years, including estimation of extreme wind speed. It can be observed that variation of yearly wind speed, monthly wind speed as well as frequency distribution of wind direction. Wind classes of buoy sites are estimated by extrapolated average wind speed using log law. In addition, wind turbine class based on IEC code is assessed for evaluation of suitable wind turbine.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2012.06a
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• pp.216-216
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• 2012

• Journal of Navigation and Port Research
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• v.46 no.1
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• pp.11-17
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• 2022

The high wind wave alert has a great impact on ships and maritime service workers navigating in the vicinity of Korea. This study aims to evaluate the appropriateness of the high wind wave alert by comparing and analyzing the observation data of major marine meteorological buoys with the high wind wave alerts in the coastal sea and offshore of the West Sea, South Sea, and the East Sea announced by the Korea Meteorological Administration for the past 11 years(2010-2020). As a result of comparing the daily, monthly, and annual statistics of the high wind wave alert and marine meteorological buoy observation data for each sea area by annual, monthly, and seasonal average, the accuracy of high wind wave alerts was very low across the entire sea area. In particular, it was analyzed that the accuracy in the coastal sea of the South Sea and Jejudo was the lowest in winter. It was confirmed that the accuracy of marine weather forecasts and alerts needs to be improved when considering the effects of the high wind wave alerts on fishing vessels, passenger ships operations and tourism, and marine leisure activities.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.5
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• pp.417-422
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• 2016

Aids to Navigation (AtoN) are marine traffic facilities to improve the safety and efficiency of shipping. "New Dangers" should be appropriately marked using lateral, cardinal or isolated danger marks or by using an Emergency Wreck Marking Buoy. However, Emergency Wreck Marking Buoys are difficult to implement in terms of speed and accuracy of installation. In the case of sinking accidents, it is often difficult to immediately install an Emergency Wreck Marking Buoy because of weather conditions, the marine environment or accident positioning. This study concerns Auto-Releasing Emergency Wreck Marking Buoys, which should be installed in all vessel for safe marine navigation and efficient maritime transport with reference to the Maritime Buoyage System (MBS). Auto-Releasing Emergency Wreck Marking Buoys include an auto-release unit, auto reel chain and auto lighting lantern. These buoys can be automatically released from the deck of a vessel and will float in the water for quick installation at the scene of an accident, even in the case of sinking accidents. Auto-Releasing New Mark Buoys are expected to reduce to installation process, prevent secondary accidents by the risk of navigation and be search and rescue rapidly.

• Journal of the Korean Institute of Navigation
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• v.16 no.1
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• pp.65-75
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• 1992

The Waterway System for the Very Large Ships is One of the Important System connected between Marine Transport System and Exclusive Terminal. This study analyzed the Turning Configurations and Placement of Fairway Buoys in Waterway at the Port of Kwangyang to make Optimal Suggestion of for Ship's Safe Navigation. The following Conclusions are drawn : 1) In Area Section A, Starboard hand Buoy No14 should be changed its Location and Light Rhythms, and Buoy Nos.13 '||'&'||' 16 are required their Light Rhythms to be changed. 2) Especially in Area Section B located before the Turning Basin, The Location and Light Rhythms of Nos.20 '||'&'||' 22 buoys at Starboard Hand should be changed, Port Hand No.21 also should be done, and East Cardinal Buoy located between Nos.21and 23 should be changed its Light Rhythms, or removed if possible. 3) Buoy no.19 of Lateral Port Hand in Section B should be changed "Preferred Channel to Startboard" to distinguish Main Channel from Secondary One.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.05a
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• pp.21-32
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• 2002

In accordance with the development plans of Ulsan harbor, Ulsan new harbor will be contructed considering supporting Ulsan harbor as a safe berthing and departure at single buoy mooring(SBM). In this study, we used a full-mission ship handling simulator adopting 300,000 DWT VLCC manoeuvered at the planned Ulsan SBM. Five masters who have had a long experience of ship maneuvering were called to carry out the simulations, of which each scenario were tried one, completed total of 68 times. The marine traffic safety was assessed in terms of 1) the closest point of approach(CPA) to other SBM and breakwater in the vicinity and the probability of crossing the restricted area of the closest SBM and fairway limit, 2) subjective evaluation such as the mental burden and the maneuvering difficulty of shiphanders, and 3) the opinions of shiphandlers. From the result of this simulation, we have a conclusion as follows; First, because crude oil berthing angle is so small by current S-OiL Co. crude oil buoy by SK Co. No 3 crude oil buoy different view SK Co. No 3 crude oil buoy and interference of current KNOC crude oil buoy, Berthing is impossible, and Emergency departing is very dangerous too operation impossible. Second it is desirable that SK Co. No 2 and No 3 Single buoy Mooring that do different view controls position so that to be not put in straight line each other. Third, SK Co. No 1 and 2 single buoy mooring that do different view to Onsanhang berthing and departing is seized by single buoy mooring by external force ship that set sail does faith control need.