• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.16 no.3
• /
• pp.171-177
• /
• 2004

A new wave gauge using digital image of waves is developed and the performances are tested by wave tank experiments. This wave gauge uses frame frequency of 1/15 sec, conversion of analog images to digital images, and large capacity of hard disk. This wave gauge measures wave heights by detecting the buoy movement automatically from the image, where the buoy moves with the same phase of water surface. The comparison of automatic measurements of wave heights to the true data is reasonable. The wave gauge can be improved to measure wave heights on shallow waters near shorelines.

• Journal of information and communication convergence engineering
• /
• v.6 no.3
• /
• pp.249-254
• /
• 2008

Moored ocean buoys are technically feasible approach for making sustained time series observation in the oceans and will be an important component of any long-term ocean observing system. The 3M disc buoy carried Zeno 3200, MCCB, Orbcomm, Global Star and Bluetooth module. The deployments have relied on Orbcomm and Global Star as the primary satellite communications system. In addition to detailing our practical experience in the use of Orbcomm and Global Star as high latitudes, we will present some of scientific sensor results regarding real-time oceanographic and meteorological parameters such as wind speed, wave height and etc. In this paper we present the design and implementation of a small-scale buoy sensor network. One of the major challenges is that the network is hard to access after its deployment and hence both hardware and software must be robust and reliable.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.18 no.4
• /
• pp.922-937
• /
• 2024

Maritime activities are on the rise, there is a growing demand for high-quality communication services that can cover larger areas. However, the transmission of high data rates to maritime users is challenging due to path loss from land base stations, which limits the transmission power. To overcome this challenge, researchers have been exploring the use of buoys in a marine environment as relays for communication technology. This paper proposes a simulation-based approach to investigate the impact of various beamwidths on communication performance when using a buoy as a relay. The objective is to determine the optimal beamwidth that yields the highest data rate for the target location. The approach is based on an offshore wave model where the direction of the buoy changes according to the height of the wave. The study investigates the performance of the relay in the downlink situation using receive beamforming, and the capacity at the user in the three-hop situation is verified using an amplify-and-forward (AF) relay that uses transmit beamforming to the user. The simulation results suggest that the beamwidth of the relay should be adjusted according to the wave conditions to optimize the data rate and relay position that satisfies a data rate superior to the direct path to the target position. Using a buoy as a relay can be a promising solution for enhancing maritime communications, and the simulation-based approach proposed in this paper can provide insights into how to optimize beamwidth for effective communication system design and implementation. In conclusion, the study results suggest that the use of buoys as relays for maritime communication is a feasible solution for expanding coverage and enhancing communication quality. The proposed simulation-based approach provides a useful tool for identifying relay beamwidths for achieving higher data rates in different wave conditions. These findings have significant implications for the design and deployment of communication systems in maritime environments.

• Journal of Ocean Engineering and Technology
• /
• v.23 no.1
• /
• pp.89-95
• /
• 2009

The purpose of the present study was to evaluate the safety under extreme environmental conditions and the dynamic safety under service environment conditions, of oceanographic buoy mooring systems consisting of a variety of materials, including chain, wire rope, nylon rope, and polypropylene rope. For the static safety assessment of a mooring system, after the calculation of external forces and the division of a mooring system into finite elements, the numerical integral was conducted to yield the elemental static tension until satisfying the geometrical convergence condition. To evaluate the dynamic safety, various processes were considered, including data collection about the anticipated areas for mooring, a determination of the parameters for the interpretation, the interpretation of the dynamic characteristics based on an analytic equation that takes into account the heave motion effect of a buoy hull and a mooring system, and a fatigue analysis of the linear cumulative damage. Based on the analysis results, a supplementary proposal for a wire rope that has a fracture in an actual mooring area was established.

• Journal of Ocean Engineering and Technology
• /
• v.31 no.5
• /
• pp.325-334
• /
• 2017

This paper reports the conceptual design process for a floating metocean data measurement system (FMDMS) for measuring wind information at sea. The FMDMS consists of three circular pontoons, columns, and a deck, which the LiDAR (lighting detection and ranging) is installed on. The dynamics of the mooring lines and motion responses of the FMDMS were analyzed using commercial codes such as WAMIT and OrcaFlex. One design criterion of the developed FMDMS was to maintain the motion responses as small as possible to enhance the LiDAR's accuracy. Starting with the preliminary design parameters such as the FMDMS's principal dimensions, weight, and important parameters of mooring system, we checked whether the FMDMS met the design requirements at each design stage, and then made modifications as necessary. The developed FMDMS showed a large pitch behavior for a small heave motion.

• Journal of Navigation and Port Research
• /
• v.36 no.8
• /
• pp.599-605
• /
• 2012

As vessels are faster and bigger, higher safety navigation techniques have been required. In marine traffic area, buoy is to be one of the most important equipment, so that it should be built stable and robust. Verification in design level is good to accomplish it. This paper tries to implement visual program to confirm the external stability, which shows the movement on water by external factors such as wind, tide and current. Considering further requirements for additional influences or functions, design architecture for program introduces the concept of software component. Using Quest3D as the graphic tool, visual programming with software component concept can be implemented.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.17 no.3
• /
• pp.174-181
• /
• 2014

Design procedure of LEG(Linear Electric Generator) is introduced by performing the time-domain analysis for the heaving motion of a floating buoy coupled with LEG. A vertical truncated buoy is selected as a point absorber and a double-sided Halbach array mover and cored slotless stator is adopted as a linear electric generator. LEG with a double-sided Halbach array mover and cored slotless stator is designed with the input data such as the heave motion velocity and wave exciting forces in time-domain. The validity of designed LEG is confirmed by performing generating-characteristic-analysis under the sinusoidal motion of a buoy, based on the numerical techniques such as FE(Finite Element) analysis. In particular, an ECM(Equivalent Circuit Method) is employed as the design tool for the prediction of generating characteristics under irregular wave conditions. Finally, we confirm that the ECM gives reasonable and fast results without sacrifice of accuracy.

• Journal of information and communication convergence engineering
• /
• v.7 no.2
• /
• pp.176-181
• /
• 2009

This study is part of a project to develop and improve mooring systems for oceanographic use that include an electro-optical sensor, 1MHz Nortek Aquadopp Doppler Profiler and AIRMAR multipurpose Sensor. The adaption of Doppler current profilers to measure directional wave spectra has provided a new instrumentation approach to coastal and nearshore oceanographic studies. The HEIOB is developed are light weight and of a compact design, and can be easily installed in marine environment. Since there are no base station and gateways in marine environments, we selected CDMA and Orbcomm to send the data information. Therefore, the data can be sent by either e-mail service or Short Message Service (SMS). This paper will present some of scientific sensor results regarding real-time oceanographic and meteorological parameters such as wind spend, wind direction, wave direction, and etc. The modeling and test results highlight the engineering challenges associated with designing these systems for long lifetimes. It can also be used in future application to build wave observation buoy network in real-time using multiple ubiquitous buoys that share wave data and allow analysis of multipoint, multi-layer wave profiler.

• Journal of the Society of Naval Architects of Korea
• /
• v.33 no.4
• /
• pp.162-174
• /
• 1996

Longline type aquaculture facilities in the open sea are based on the cable-buoy-weight mooring system. For their optimal design it is necessary to estimate tensions along the mooring lines including the attachment points of buoys and weights. However, the dynamic analysis is very complicated due to the nonlinear behaviors of the mooring lines and the effects of wave and current. In this paper, parametric studies for various buoy-weight cases are shown. Finite difference scheme is employed in obtaining eigenfrequencies in the frequency domain. Nonlinear hydrodynamic drag forces are equivalently linearized.

• Journal of Ocean Engineering and Technology
• /
• v.15 no.2
• /
• pp.22-32
• /
• 2001

The numerical investigation of obliquely incident wave interactions with fully submerged dual buoy/porous-membrane floating breakwaters placed in parallel with spacing is studied based on linear potential theory and Darcy's law. The numerical solutions are obtained by using a discrete-membrane dynamic model and second-kind modified Bessel function distribution over the entire boundaries of fluid regions. First, numerical solutions for an idealized dual submerged system without buoys are obtained. Second, a more practical dual submerged system with membrane tension provided by buoys at its tops is investigated by the multi-domain boundary element method particularly devised for dual buoy/porous-membrane problems with gaps. The velocity potentials of wave motion are coupled with porous-membrane deformation, and solved simultaneously since the boundary condition on porous-membrane is not known in advance. The effects of varying permeability on membranes and wave characteristics are discussed for the optimum design parameters of systems previously studied. The inclusion of permeability on membrane eliminates the resonances that aggravate the breakwater performance. The system is highly efficient when waves generated by the buoys and membranes were mutually canceled and its energy at resonance frequency dissipates through fine pores on membranes.