• Journal of the Korean Society for Marine Environment & Energy
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• v.5 no.2
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• pp.35-40
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• 2002

By the introduction of cleaning and drying processes, thermal extrusion system for the volume reduction of used polystyrene buoys was developed. It was tested in the costal area for the determination of operational reliability. By the removal of oyster shells and cleaning of salt, waste polystyrene buoys was changed to the raw material of plastics. The lower cost of one-tenth compared with that of the outer request treatment is promising the practical use of waste buoys' volume reduction system.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.3
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• pp.193-202
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• 2014

This paper presents a new method of sampling the climatic data for infrared signature analysis. Historical hourly data from a stationary marine buoy of KMA(Korean Meteorological Administration) are used to select a small number of sample points (N=100) to adequately cover the range of statistics(PDF, CDF) displayed by the original data set (S=56,670). The method uses a coarse bin to subdivide the variable space ($3^5$=243 bins) to make sample points cover the original data range, and a single-point ranking system to select individual points so that uniform coverage (1/N = 0.01) is obtained for each variable. The principal component analysis is used to calculate a joint probability of the coupled climatic variables. The selected sample data show good agreement to the original data set in statistical distribution and they will be used for statistical analysis of infrared signature and susceptibility of naval ships.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.33-36
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• 2007

We have persistently constructed gridded products of surface wind/wind stress over the world ocean using satellite scatterometer (ERS and Qscat). They are available for users as the Japanese Ocean Flux data sets with Use of Remote sensing Observation (J-OFURO) data together with heat flux components. Recently, a new version data of the Qscat/SeaWinds based on improved algorithm for rain flag and high wind-speed range have been delivered, and allowed us to reconstruct gridded product with higher spatial resolution. These products are validated by comparisons with in-situ measurement data by mooring buoys such as TAO/TRITON, NDBC and the Kuroshio Extension Observation (KEO) buoys, together with numerical weather prediction model products such as the NCEP-1 and 2. Results reveal that the new product has almost the same magnitude in mean difference as the previous version of Qscat product and much smaller than the NCEP-1 and 2. On the other hand, it is slightly larger root-mean-square (RMS) difference than the previous one and NCEPs for the comparison using the KEO buoy data. This may be due to the deficit of high wind speed data in the buoy measurement. The high resolution product, together with sea surface temperature (SST) one, is used to examine a new type of relationship between the lower atmosphere and upper ocean in the Kuroshio Extension region.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.3
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• pp.287-297
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• 2019

The recent increase in crude oil trading has led to an increase in the workings of SPM for crude oil carriers. VLCCs generally encounter difficulty entering port due to limitations in terms of sea depth and maneuverability. The SPM is a system that allows mooring to the buoy located in the outer sea for such vessels. However, the buoy is more affected by relatively external forces because of their of shore location. Therefore, the safety assessment of SPM is particularly important as it can lead to large oil pollution disasters in the event of SPM accidents. Despite this, in the implementation of the Marine Traffic Safety Audit Scheme in Korea, there exists no guidance for SPM. In this study, a SPM mooring safety assessment is performed using OPTIMOOR, a numerical analysis program, so as to understand the mooring characteristics of SPM. As a result, it is confirmed that the tension of mooring lines and hull movement in the SPM are greatly affected by the encounter angles with external forces. In addition, it is found that the maximum tension of the mooring line is elevated as the water depth becomes shallower through sensitivity analysis. According to SPM characteristics, which has a large influence on the encounter angle, this study has proposed an amendment to setting criteria in the implementation of the Maritime Traffic Safety Audit Scheme which could improve the reliability and accuracy of mooring safety assessments.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.1
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• pp.9-15
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• 1998

Hourly meteorological data from a marine buoy ($34^{\circ}49'00"N$, $125^{\circ}46'00"E$) operated by the Korean Meteorological Agency were obtained from July, 1996 to February, 1997. From the data air-sea heat fluxes and marine meteorological characteristics around the area are estimated. The maximum outflux of sensible heat from the sea surface occurred in January (monthly mean value, 12.6 $Wm^{-2}$ and the maximum influx to the sea occurred in July (monthly mean value, 5.5 $Wm^{-2}$). This means that the sea is heated in summer while it loses its heat in winter, and that there is inequality between the absolute values of the two seasons. The outflux of the maximum latent heat occurred in November (monthly mean value, 86.5 $Wm^{-2}$) and reach a value of 300 $Wm^{-2}$, and the maximum influx occurred in July (monthly mean value, 4.6 $Wm^{-2}$). Big difference is shown in their absolute values when the wind becomes strong. The outgoing latent heat flux reaches its maximum in autumn, and it maintains the high value through the whole winter. According to the wave data analysis, the significant wave heights are larger in winter than in summer. The periods of the significant waves are 4~6 sec. In winter, waves propagated from north and northeast are dominant because of the winter monsoon, while in summer waves from south, southwest, and west are relatively frequent.

• Journal of Navigation and Port Research
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• v.44 no.3
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• pp.158-165
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• 2020

Buoys are a necessary component for the safety of vessel traffic. However, if the buoy becomes inoperable from damage and loss, it can have significant impact on vessel traffic safety as well as unexpected budget spending. The purpose of this study was to evaluate the risk of accidental contact by applying the marine traffic assessment index that can reflect the traffic flow in the sea area. First, Busan Port No. 5 fairway, with a high number of buoys and many contact accidents, was set as the sea area for assessment. to investigate the status of accidental contact and evaluate risk of contact accidents based on the IALA Waterway Risk Assessment Programme (IWRAP MkII) and Potential Assessment of Risk Model (PARK Model). As a result, buoys are near the P recautionary Area wherein the traffic flow was complicated by the Masan port vessel and Busan new port vessel, and buoys are near the entrance of the Gadeok waterway, wherein vessels show a pattern of navigation across the fairway and buoys are near the breakwater in the inner fairway were considered as high risk for contact accidents. This study can be used as basic data for establishing an integrated model to evaluate the risk of buoy contact accidents.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.3
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• pp.174-181
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• 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 the Korea Institute of Information and Communication Engineering
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• v.22 no.7
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• pp.1021-1029
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• 2018

The marine buoys are operated in various domains, which are navigation route and danger maker, weather and environment monitoring, military strategical element, etc. If the marine buoy is damaged, there consumes many cost and time for recovery or replacement, because of severe environmental condition, and causes a risk possibility of secondary accident. In this paper, we developed an active monitoring and approach alarm providing system using trail cameras and AIS for protection for the marine buoys. To do this, we analyzed existing researches and similar systems, extracted requirements for enhancement, and designed the system architecture that applied the enhanced elements. The main considerations of system enhancement are: integration of AIS and trail cameras, adopting of phased alarm technique by approaching ships, applying of selective communication module, conducting the image processing of ships for providing alarm, and applying thermal cameras. After that, we developed the system using designed architecture and verified effectiveness of the system based on laboratory or field-level tests.

• Journal of IKEEE
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• v.24 no.4
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• pp.1069-1073
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• 2020

This paper presents the performance analysis of a long-range marine communication system developed for monitoring the fishing gears. LoRa based buoys were developed to monitor fishing gears. The buoy sends its coordinates along with other relevant information to the central monitoring station via a gateway. During the experiment, a up to 30 km of communication between a buoy and a gateway was successfully tested.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.4
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• pp.588-594
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• 2009

The maximum power point operation point(MPPOP) of photovoltaic(PV) power generation systems changes with varying atmospheric conditions such as temperature, solar radiation. For achieving a high efficiency in PV system, it is very important for PV system to track the MPPOP correctly according to operation condition. Although the MPPT(maximum power point tracking) algorithm which applied P&O(Perturbation & Observation) or IncCnd(Incremental Conductance) algorithm tracks the MPPOP efficiently, its efficiency drops noticeably in case that the incidence angle of PV panel on buoy changes rapidly. To solve this problem, this paper proposes maximum power point searching and tracking algorithm(MPPST). The proposed algorithm set the specific area and measures the PV voltage at the same interval. The proposed algorithm have been obtained high efficiency than P&O algorithm through ocean experiment.