• 한국해양환경ㆍ에너지학회지
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• 제15권3호
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• pp.170-176
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• 2012

본 논문은 서남해안 4개의 해양관측부이에서 계측된 해상 기상 및 파랑 자료를 수집하여 태풍 무이파 내습전후의 해상상태를 분석하였다. 태풍이 목포 서쪽 약 230 km 부근 해상에 위치할 때(2010년 8월 7일 21시) 기압 저하에 의한 해수면 상승량은 칠발도 25.64 cm, 거문도 16.43 cm, 거제도 9.60 cm로 산정되었다. 또한 최대파고 발생 시점 비교 결과, 특징적으로 거문도가 칠발도에 비해 약 7시간 앞서 발생하였다. 태풍 내습시 칠발도 해역에서 저수온 현상이 발생하였는데 이는 파랑에너지의 감소 요인으로 작용하였을 것으로 생각된다. 태풍 내습시 풍향과 파향은 S 및 W계열이 발달함으로써 바람이 해수를 해상에서 연안(해안) 방향으로 수송하는 외력으로 작용한 것으로 판단된다. 태풍 내습시 각 부이별 기상 및 해양 요소를 상호 비교한 결과, 마라도 부이는 칠발도 부이 결과와는 음의 상관성을, 거문도와 거제도 부이와는 양의 상관성을 보이고 있음을 알 수 있다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권4호
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• pp.739-749
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• 2015

A new conceptual dual-buoy Wave Energy Converter (WEC) for the enhancement of energy extraction efficiency is suggested. Based on actual wave data, the design process for the suggested WEC is conducted in such a way as to ensure that it is suitable in real sea. Actual wave data measured in Korea's East Sea (position: $36.404N^{\circ}$ and $129.274E^{\circ}$) from May 1, 2002 to March 29, 2005 were used as the input wave spectrum for the performance estimation of the dual-buoy WEC. The suggested WEC, a point absorber type, consists of two concentric floating circular cylinders (an inner and a hollow outer buoy). Multiple resonant frequencies in proposed WEC affect the Power Ttake-off (PTO) performance of the WEC. Based on the numerical results, several design strategies are proposed to further enhance the extraction efficiency, including intentional mismatching among the heave natural frequencies of dual buoys, the natural frequency of the internal fluid, and the peak frequency of the input wave spectrum.

• 센서학회지
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• 제31권1호
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• pp.64-68
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• 2022

Herein, we propose a LoRaWAN-based small draft system that can measure the ocean current flow (speed, direction, and distance) in real time at the request of the Coast Guard to develop a device that can promptly find survivors at sea. This system has been implemented and verified in the early stages of rescue after maritime vessel accidents, which are frequent. GPS signals often transmit considerable errors, so correction algorithms using the improved triangulation method algorithm are required to accurately indicate the direction of currents in real time. This paper is structured in the following manner. The introduction section elucidates rescue activities in the case of a maritime accident. Chapter 2 explains the characteristics and main parameters of the GPS surveying technique and LoRaWAN communication, which are related studies. It explains and expands on the critical distance error correction algorithm for GPS signals and its improvement. Chapter 3 discusses the design and analysis of small draft buoys. Chapter 4 presents the testing and validation of the implemented system in both onshore and offshore environments. Finally, Section 5 concludes the study with the expected impact and effects in the future.

• 수산해양기술연구
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• 제54권4호
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• pp.271-278
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• 2018

In this study, the conventional cylinder-shaped lower bar on the canvas was modified and its performance was tested to improve the opening force of the stow net on anchor. The improved new lower bar used in the test is consisted of 13 flat bars with a length of 1.8 m, a width of 0.075 m and a thickness of 4 mm, and a pipe with a length of 2.0 m and a diameter of 50 mm. A stow net with the improved lower bar and a stow net with an existing lower bar were installed underwater and their trajectories for 21 hours were examined. To confirm their trajectories, GPS loggers were attached to the buoys on the left and right canvases and the buoy of the hauling rope. As a result of the test, the rotation of the gear with the improved bar was smoother than that with the existing bar. As a result of comparing the changes in the interval of the buoys attached to the canvas after the low and high tide, the buoy spacing of the gear with the improved bar is wider than that of the conventional gear; moreover, the larger the interval, the smoother the rotation of the fishing gear was. Therefore, it is considered that using the improved lower bar can enhance the performance of the stow net.

• Journal of information and communication convergence engineering
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• 제6권3호
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• pp.249-254
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• 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.

• 한국해양공학회지
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• 제29권3호
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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.

• 한국해양공학회지
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• 제35권4호
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• pp.305-312
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• 2021

There is a gradual increase in the need for energy charging in marine environments because of energy limitations experienced by electric ships and marine robots. Buoys are considered potential energy charging systems, but there are several challenges, which include the need to maintain a fixed position and avoid hazards, dock with ships and robots in order to charge them, be robust to actions by birds, ships, and robots. To solve these problems, this study proposes a smart buoy robot that has multiple thrusters, multiple docking and charging parts, a bird spike, a radar reflector, a light, a camera, and an anchor, and its mechanism is developed. To verify the performance of the smart buoy robot, the position control under disturbance due to wave currents and functional tests such as docking, charging, lighting, and anchoring are performed. Experimental results show that the smart buoy robot can operate under disturbances and is functionally effective. Therefore, the smart buoy robot is suitable as an energy charging system and has potential in realistic applications.

• 한국항해항만학회지
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• 제47권6호
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• pp.350-357
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• 2023

해상특보가 발효되었을 때 평수구역 내에서 선박출항통제 대상에서 제외되는 선박의 무리한 운항으로 인한 사고가 빈번하게 발생하고 있다. 평수구역 내에 설치된 파고부이는 선박출항통제의 주요 참고 지표이며 평수구역 및 연안을 항행하는 선박의 안전과 직결된다고 볼 수 있다. 이 연구에서는 최근 30년간(1991~2020년)의 연안 해양사고, 각 무역항의 주풍향 및 풍속, 2018년 GICOMS 선박 항적 데이터 분석을 통하여 현재 운영 중인 파고부이의 위치 적절성 및 평수구역 내 파고부이 추가설치에 대한 평가를 수행하였다. 연구 결과 국내 주요 무역항인 인천항, 포항항, 울산항 및 부산항에 각 1개의 파고부이 추가설치가 필요하며, 부산항의 경우 파고부이 1개의 위치 이동이 필요한 것으로 검토되었다. 이 연구에서 여러 가지 데이터 분석을 바탕으로 제시된 파고부이의 추가설치 및 이동에 대한 제언은 선박출항통제의 신뢰도 향상 및 안전사각지대 해소에 기여할 것으로 판단된다.

• 한국해양공학회지
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• 제30권6호
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• pp.440-450
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• 2016

The capsizing and consequent sinking of a coastal car ferry was recently reported, with numerous human casualties. The primary cause was determined to be a sudden turn with improperly stowed and secured cargo. Part I of this study introduces how long term acceleration components are determined from seakeeping analyses. A carferry with a displacement of 1,633 tonf was selected as the target vessel. Sea data that included the significant wave heights and periods were collected at four observation buoys, some of which were far away from two main voyage routes: Incheon-Jeju and Pusan-Jeju. Frequency response analyses were performed to obtain the linearized radiation force coefficients, hydrostatic stiffnesses, and wave excitation forces. Time response analyses were sequentially performed to produce the motion-induced acceleration processes. The probabilistic distributions of the acceleration components were determined using a peak and valley counting method. Long term extreme acceleration components were proposed as a final result.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권1호
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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.