• Journal of Advanced Navigation Technology
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• v.25 no.5
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• pp.397-402
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• 2021

The real-name electric fishing gear system is one of the important policy capable to build 'abundant fishing ground' and to protect marine environment. And, fishing gear automatic-identification system is one of IoT services that can implement above-mentioned policy by using communication such as low power wide area (LPWA) and multi-sensing techniques. Fishing gear automatic -identification system can gather the location data and lost/hold data from electric buoy floated in sea and can provide them to fishermen and monitoring center in land. We have developed the communication modules and electric buoy consisted of fishing gear automatic-identification system. In this paper, we report the test results of communication distance between electric buoy and wireless node installed in fish boat and location error of electric buoy. It is confirmed that line of sight (LOS) distance between electric buoy and wireless node is obtained to be 62 km, which is two times of the desired value, and location error is obtained to be CEP 1 m, which is smaller than the desired value of CEP 5 m. Therefore, it is expected that service area and accuracy of the developed fishing gear automatic-identification system is more extended.

• Ocean Systems Engineering
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• v.10 no.2
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• pp.181-199
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• 2020

Cyclone Heat Potential (CHP) is an essential parameter for accurate prediction of the intensity of tropical cyclones. The variability of the heat storage in the near-surface layers and the vertical stratification near the surface due to large fresh water inputs create challenges in predicting the intraseasonal and interannual evolution of monsoons and tropical cyclones in the Bay of Bengal. This paper for the first time presents the D26- referenced cyclone heat potential observed in the Bay of Bengal during the period 2012-17 based on the in-situ data collected from 5.5 million demanding offshore instrument-hours of operation in the Ocean Moored Buoy Network for Northern Indian Ocean (OMNI) buoy network by the National Institute of Ocean Technology. It is observed that the CHP in the Bay of Bengal varied from 0-220 kJ/㎠ during various seasons. From the moored buoy observations, a CHP of ~ 90 kJ/㎠ with the D26 isotherm of minimum 100m is favorable for the intensification of the post-monsoon tropical cyclones. The responses of the D26 thermal structure during major tropical cyclone events in the Bay of Bengal are also presented.

• Ocean Systems Engineering
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• v.3 no.3
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• pp.203-217
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• 2013

A PTO (power-take-off) mechanism by using relative heave motions between a floating buoy and its inner mass (magnet or amateur) is suggested. The inner power take-off system is characterized by a mass with linear stiffness and damping. A vertical truncated cylinder is selected as a buoy and a special station-keeping system is proposed to minimize pitch motions while not affecting heave motions. By numerical examples, it is seen that the maximum power can actually be obtained at the optimal spring and damper condition, as predicted by the developed WEC(wave energy converter) theory. Then, based on the developed theory, several design strategies are proposed to further enhance the maximum PTO, which includes the intentional mismatching among heave natural frequency of the buoy, natural frequency of the inner dynamic system, and peak frequency of input wave spectrum. By using the intentional mismatching strategy, the generated power is actually increased and the required damping value is significantly reduced, which is a big advantage in designing the proposed WEC with practical inner LEG (linear electric generator) system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.614-617
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• 2000

To get the maximum diffusion boundary of thermal effluent of Youngkwang Nuclear Power Plant, paths of TGPS Buoy and temperatures of surface water are obtained to 4 times at spring tide during 1 year. According to the paths of TGPS Buoy, the flumes of thermal effluent are moved about 12km from outlet to SW or WSW direction. After 3∼4 times of tidal period the waters are reached to Chilsan Island because the ebb flow is more predominant than the flood flow in this area. At the spring and fall season, a sudden drop of surface water temperature is detected around 5km radius from the outlet. At the summer season, it is measured about 10km. On the other hand the flumes are continuously cooled down by the atmosphere condition at winter season.

• Journal of Navigation and Port Research
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• v.32 no.9
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• pp.705-709
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• 2008

In the sea various methods have been conducted to capture wave energy which include the use of pendulums, pneumatic devices, etc. Floating devices, such as a cavity resonance device take advantages of both the water motion and the wave induced motions of the floating body itself. The wave energy converter is known commercially as the WAGB(Wave Activated Generator Buoy) and is used in some commercially available buoys to power navigation aids such as lights and horns. This wave energy converter consists of a circular flotation body which contains a vertical water column that has free communication with the sea. A theoretical analysis of this power generated by a pneumatic type wave energy converter is performed and the results obtained from the analysis are used for a real wave energy converter buoy. This paper is shown to have an optimum value for which maximum power is obtained at a given resonant wave period Also, the length of the internal water column corresponds to that of the water mass in the water column. If designed properly, wave energy converter can take advantage not only of the cavity resonance, but also qf the heaving motion of the buoy. Finally, simulation is performed with a LabVIEW program and the simulation results are applied to a wave energy simulator for modifying design data for a wave energy converter.

• Journal of the Korean Association of Geographic Information Studies
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• v.5 no.2
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• pp.47-53
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• 2002

Ocean surface wind speed was estimated using TRMM (Tropical Rainfall Measurement Mission) TMI (TRMM Microwave/Imager) data. It is used the TRMM TMI brightness temperature and National Data Buoy Center's buoy winds speed dataset near North-America to estimate by the algorithm of the ocean surface wind speed retrieval over North America. Comparing with the buoy data by D-matrix equation, the result that RMSE, BIAS, and correlation coefficient are 2.19 $ms^{-1}$, 1.10 $ms^{-1}$, and 0.81, respectively. Therefore the estimated oceanic surface wind speed by TRMM TMI brightness temperature data show that available to ocean research over upper ocean.

• Ocean and Polar Research
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• v.31 no.4
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• pp.401-414
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• 2009

Yellow Sea Buoy (YSB) was moored in the center of the Yellow Sea at 35$^{\circ}$51'36"N, 124$^{\circ}$34'42"E, on 12 September 2007. YSB is a large buoy of 10 m diameter, and as such is more durable against collision by ships and less likely to be lost or removed by fishing nets compared to small ordinary buoys of 2.3 m diameter. YSB is equipped with 12 kinds of oceanic and meteorologic instruments, and transfers its realtime observation data to KORDI through ORBCOMM system every 1 hour. Data on ocean winds, air temperature, air pressure, and sea temperature appear to be accurate, while water property sensors (AAQ1183), which are sensitive to fouling, are producing errors. YSB (2007), Ieodo ocean research station (2003), and Gageocho ocean research station, which was completed in October 2009, will establish the 2 degrees interval by latitude in the Yellow Sea, and they will contribute though the 'Operational Oceanography System' as the important realtime observation network.

• Journal of Ocean Engineering and Technology
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• v.15 no.2
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• pp.11-21
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• 2001

The focus of this paper is on the numerical investigation of obliquely incident wav interactions with a system composed of fully submerged and floating dual buoy/vertical-flexible-membrane breakwaters placed in parallel with spacing between two systems. The fully submerged two systems allow surface and bottom gaps to enable wave transmission over and under the system. The problem is formulated based on the two-dimensional multi-domain hydro-elastic linear wave-body interaction theory. The hydrodynamic interaction of oblique incident waves with the combination of the rigid and flexible bodies was solved by the distribution of the simple sources (modified Bessel function of the second kind) that satisfy the Helmholz governing equation in fluid domains. A boundary element program for three fluid domains based on a discrete membrane dynamic model and simple source distribution method is developed. Using this developed computer program, the performance of various dual systems varying buoy radiuses and drafts, membrane lengths, gaps, spacing, mooring-lines stiffness, mooring types, water depth, and wave characteristics is thoroughly examined. It is found that the fully submerged and floating dual buoy/membrane breakwaters can, if it is properly tuned to the coming waves, have good performances in reflecting the obliquely incident waves over a wide range of wave frequency and headings.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.7
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• pp.1003-1010
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• 2013

In this paper, TCP/IP based Machine-to-Machine (M2M) communication uses CDMA/GSM network for data communication. This communication method is widely used by offshore moored buoy for data transmission back to the system server. Due to weather and signal coverage, the TCP/IP M2M communication often experiences transmission failure and causing data losses in the server. Data losses are undesired especially for meteorological and oceanographic analysis. This paper discusses a software approach to minimize M2M data losses by handling transmission failure and re-attempt which meant to transmit the data for recovery. This implementation was tested for its performance on a meteorological buoy placed offshore.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.155-160
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• 2002

In this paper, a compliant buoy mooring system of a floating cylindrical structure in shallow water depth is studied experimentally. The compliant buoy mooring system consists of four buoys, vertical mooring legs and horizontal mooring lines. A series of model test were carried out at KRISO ocean engineering basin for various mooring parameters; line length, pretension of mooring leg and mooring layouts and environmental conditions; regular and irregular waves combined with current and wind. The mooring line tensions and 6-DOF motions of the floating structure were measured using water-proof load cells and 3 CCD camera system. The results of a series of model tests were discussed on nonlinear motion behaviors of the floating structure and characterisitics of cumulative distributions of mooring line peak tensions.