• Journal of Ocean Engineering and Technology
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• v.29 no.3
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• pp.249-254
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• 2015

Buoys are widely used in marine areas because they can mark positions and simultaneously acquire and exchange underwater, surface, and airborne information. Recently, the need for controlling and optimizing a buoy's position and attitude has been raised to achieve successful communication in a heterogeneous collaborative network composed of an underwater robot, a surface robot, and an airborne robot. A buoy in the form of a marine robot would be ideal to address this issue, as it can serve as a moving node of the communication network. Therefore, a buoy-based autonomous surface robot-kit with the abilities of sonar-based avoidance, dynamic position control, and static attitude control was developed and is discussed in this paper. The test and evaluation results of this kit show the possibility of real-world applications and the need for additional studies.

• Bulletin of the Society of Naval Architects of Korea
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• v.23 no.3
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• pp.1-9
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• 1986

Herein the dynamic response of an axisymmetric buoy to regular wave is studied within linear potential theory. The buoy has a particular geometry so that it should experience minimum wave-exiting force on the vertical direction at a precribed wave number in water of finite depth. Invoking the Green's theorem a velocity potential is generated by distributing pulsating sources and doublets on the immersed surface of the buoy at its mean position. Hydrodynamic forces and moments are obtained approximately by summation of the products of linear pressure and directional mesh area over the immersed surface. Model tests are carried out to measure the wave-exciting forces, hydrodynamic forces and motion responses. The experimental results in general agree fairly well with the numerical ones. From the analytical and experimental works it is found that the pitching motion and its coupling effect affect significantly the motion characteristics of the freely-floating axisymmetric buoy in regular waves.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.10a
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• pp.127-128
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• 2009

대형 유조선에서 기인된 1995년 Sea Prince호 및 2007년 Hebei Spirit호 사고 등 대다수의 재난적 유류유출사고는 많은 변수 중 "악천후"라는 기상적 어려움으로 초동방제활동 및 피해규모의 축소가 어려운 실정이다. 하지만, 정작 사고선박에서는 방제활동 주도기관의 개업이 있기 전까지 적극적인 방제활동이 이뤄지지 못하고 있는 실정이다. 사고선박에서 유출되는 유류의 확산범위 및 이동방향에 대한 정보는 추후에 예정된 방제활동에 있어서 가장 중요한 요소 중 하나이다. 이 중요한 정보의 획득을 위해 사고선박에서 설치가 가능하며, 이후 방제활동에 중요한 유출유의 확산 정보를 제공할 수 있는 유류확산 추적부이 (NOST-Buoy)의 개발연구가 필요하다.

• Journal of Magnetics
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• v.18 no.3
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• pp.250-254
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• 2013

In this research, the linear electrical generator in wave energy farm utilizing resonance power buoy system is studied. The mechanical resonance characteristics of the buoy and the wave are analyzed to maximize the kinetic energy in a relatively small wave energy area where WRPS is operated. In this research, we chose an analog model of the linear electrical generator of which size is one-hundredth of an actual size of it in WPRS (Wave energy farm utilizing Resonance Power buoy System) prior to verifying the characteristics of actual model of linear electrical generator in WRPS. In addition, the finite element analysis is conducted using commercial electromagnetic analysis software named MAXWELL to examine the electric characteristic of linear generator. Finally, for the verification of dynamic and electric characteristics of linear generator, the prototype was manufactured and the experiments to measure the displacement and the output electric power were performed.

• Journal of the Korean Solar Energy Society
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• v.37 no.1
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• pp.1-14
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• 2017

A series of coupled time domain simulations considering stochastic waves and wind based on five 1-h time-domain analyses are performed in normal operating conditions. Power performance and tower base Fore-Aft bending moment and pitching motion response of the floating spar-buoy wind turbine with 2 MW direct-drive PMSG have been analyzed by using HAWC2 that account for aero-hydro-servo-elastic time domain simulations. When the floating spar-buoy wind turbine is tilted in the wind direction, maximum of platform pitching motion is close to $4^{\circ}$. Statistical characteristics of tower base Fore-Aft bending moment of floating spar-buoy wind turbine are compared to that of land-based wind turbine. Maximum of tower base Fore-Aft bending moment of floating spar-buoy wind turbine and land-based wind is 94,448 kNm, 40,560 kNm respectively. This results is due to changes in blade pitch angle resulting from relative motion between wave and movement of the floating spar-buoy wind turbine.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.3
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• pp.274-284
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• 2003

The analysis of wave parametric characteristics in sea regions in the vicinity of Korean Peninsula have been carried out using the third generation wave model, WAVEWATCH-III (Tolman, 1999) and four observed buoy data of Korea Meteorological Administration (KMA). Significant wave height increases about 2-3 hours later after the increase of wind speed. Maximum correlation coefficient between two parameters appears in Donghae buoy data, which is at off-shore region. When land breeze occurs, it can be found that the correlation coefficient decreases. Time differences between wind speeds and wave heights correspond to significant tidal periods at all of the buoy locations except for Donghae buoy. After verifying the WAVEWATCH-III model results by the comparing with observed buoy data, we have carried out numerical experiments near the Kuroshio current and East Sea areas, and then reconfirmed that when there exist an opposite strong current in the propagation direction of the waves or wind direction, wave height and length get higher and shorter, respectively and vice versa. It has been shown that these modulations of wave parameters are considerable when wind speed is week or mean current is relatively strong, and corresponding values have been represented.

• Journal of Navigation and Port Research
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• v.32 no.5
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• pp.327-332
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• 2008

This paper analyzed the visual range and arrangement of light buoy on navigation officers as the primary material to establish the standard of optimal arrangement of light buoy on the channel of the domestic trade-port. About $30{\sim}150$ questionnaires by port were distributed according to the scale of trade-ports and then Effective total 356 copies were used in analysis. The distance, $2{\sim}4$mile, occupied the highest percentage 55.0% as the visual range with naked eyes at the daytime in bright weather. At the arrangement way of light buoy the both sides buoy method showed high in the preference 62.1% among the respondents. The preferred interval between sequence buoys was averagely 1.09mile. Also, the preferred number of light buoy was two in the preference 40.6% among them to cognize without binoculars.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.4
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• pp.299-307
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• 2016

This study aims to investigate effects of the length of the buoy and sand bag line on the loss of webfoot octopus pot. A numerical modeling and simulation was carried out to analyze the process that the pot gear affected by wave using the mass spring model. Through the simulation, tensions of sand bag line under various condition were investigated by length of buoy and sand bag line. The drag force and coefficient k of an artificial shell used in the webfoot octopus pot was obtained from an experiment in a circular water channel, and the coefficient k was applied to the simulation. To verify the accuracy of the simulation model, a simple test was conducted into measuring a rope tension of a hanging shell under flow. Then, the test result was compared with the simulation. The lengths of the buoy line in the simulation were 1.12, 1.41, 1.80, 2.23, 2.69, and 3.17 times of water depth. The lengths of sand bag line were 10, 20, 30, and 40 meters, and conditions of water depth were 8, 15, 22 meters. 4 meter height and 8 second period of wave were applied to all simulations. As a results, the tension of the sand bag line was decreased as the buoy and sand bag line were increased. The minimum tension of the sand bag line was appeared in conditions that the length of the buoy line is twice of water depth and the sand bag line length is over 40 meters (except in case of depth 8 meters.).

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.5
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• pp.497-502
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• 2013

There are currently 10 types of buoy, mostly which' design and development is dependent on foreign technology. In this study, it is aimed at the development of small instrumentation buoy and at the design proposal presented a numerically safety. The numerical method has the simulation of variety of marine environments, such as wave response amplitude ratio and each flux changes. Through the numerical simulation of buoy's kinetic movement, it is analyzed that Pitching motion increases by the frequency response of encounter and Added resistance appears to be the most significant on transverse waves. Finally, the proposed buoy is confirmed with the response' safety under simulation' conditions.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2140-2146
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• 2014

Ocean buoys are operated for safe navigation and collecting ocean data. Recently, to reducing marine buoy's damage by ocean weather's bad condition and collision with vessels has been conducted in several field research. This paper's experiment is buoy condition monitoring about predefined data form by users. As a result using Wireless remote control board applying a radio signal processing algorithms, it can observe buoy's state at an interval of three minutes on the land. Acquired data type is changeable according to ocean weather condition or buoy's purpose of using in advance. Also, this paper conducted an experiment such as data-transmission's stability and wireless communication's availability. As results of the analysis of the transmitted data, the solar, wind and wave power indicates the maximum amount of power, 50 W, 20 W and 40 W respectively. The communication system proven through this research can apply to buoy or other ocean facility.