• Journal of Magnetics
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• 제18권3호
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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.

• 한국해안·해양공학회논문집
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• 제27권1호
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• pp.50-55
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• 2015

본 연구에서는 등부표를 이용하여 외해에서 입사되는 파랑에너지를 전기에너지로 변환시키는 파력발전 방식에 대하여 연구하였다. 등부표와 직선형과 시소형 자가 발전체를 1/10 축소 모형으로 제작하고, 파랑수조에서 실험을 실시하였다. 이러한 시스템에서 서로 다른 파고와 주기를 갖는 파랑을 대상으로 등부표의 수평 및 수직 경사, 발생 전류와 에너지를 측정하였다. 이를 통하여 전기 에너지 획득 가능성을 확인하였고, 차후 연구 과제를 제안하였다.

• 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.

• 한국항행학회논문지
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• 제25권5호
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• pp.397-402
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• 2021

전자 어구 실명제는 '풍요로운 어장' 조성과 해양 환경 보호를 실행할 수 있는 주요 정책 중 하나이다. 또한 어구 자동식별 시스템은 LPWA 등의 통신과 멀티 센싱 기술을 활용하여 위 정책을 실현할 수 있는 해양 IoT 서비스 중 하나이다. 어구 자동식별 시스템은 해상에 부유하고 있는 전자 부이로부터 어구의 위치 및 유실 정보를 수집하고 어민이나 육상 관제국에게 제공한다. 어구 자동식별 시스템을 구성하는 전자 어구와 통신 장치들을 개발하였다. 본 논문에서는 전자 어구와 어선에 설치되는 무선 노드 사이의 통신 거리 측정과 전자 어구의 위치 정보 오차 측정 내용 및 결과에 대해 살펴본다. 측정 결과 통신 결과 목표치인 30 km의 2배인 62 km 거리에서 LOS 통신이 가능한 것을 확인하였고, 위치 오차는 목표치인 CEP 5 m 보다 적은 1 m의 결과를 얻었다. 따라서 본 연구를 통해 개발된 어구 자동식별 시스템의 서비스 영역과 정확도가 더욱 신장될 것으로 기대된다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.171-171
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• 2010

An innovative design of a floating-buoy wave energy converter (WEC) using hydrostatic transmission (HST), named HSTWEC, is presented in this paper. The system is designed to convert ocean wave fluctuation into electricity by using the HST circuit and an electric generator. Based on the floating-buoy concept, the wave forces the sub-buoy to move up and down. Consequently, the electric power can be obtained from the generator in both the moving directions of the sub-buoy through the HST circuit as shown in Fig. 1. In order to investigate the HSTWEC operations, a mathematical model of the system is indispensible. In addition, the method to control the HSTWEC, including: pump displacement control, tension adjustment control and ballast weight control, is also discussed in this paper. Finally, the design concept as well as simulation results indicated that this HSTWEC design is an effective solution and possible to fabricate for wave energy generation.

• 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.

• 한국해양공학회지
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• 제29권2호
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• pp.191-198
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• 2015

In this study, we proposed a new type of dual-buoy wave energy converter (WEC) exploiting multi-resonance and analyzed the experimental results from a model test in a 2-D wave flume. A dual-buoy WEC using multi-resonance has two advantages: high efficiency at the resonant frequencies and the potential to extend the frequency range available to extract wave power from the WEC. The suggested WEC was composed of an outer buoy and an inner buoy sliding vertically inside the outer buoy. As the power take-off device, a linear electric generator (LEG) consisting of permanent magnets and coils fixed at each buoy was adopted. Electricity was produced by the relative heave motion between the two buoys. To search for the optimal shape of a dual-buoy WEC, we conducted experiments on the heave motion of a two-body system in regular waves without an LEG installed. Model tests with six combinations of experimental models were conducted in order to find the motion characteristics of a dual-buoy WEC. It was found that model 2, which included a ring-shaped appendage to move the resonant frequency of the outer buoy toward a high value, showed a higher relative heave response amplitude operator (RAO) curve than model 1. In addition, the double-peak shape of the heave RAO curve shown for model 2 indicated the extension of the frequency range for extracting wave power in irregular waves.

• Ocean Systems Engineering
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• 제3권3호
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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.

• 한국정보통신학회논문지
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• 제22권5호
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• pp.779-786
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• 2018

해양수산부는 2016년 유실어구에 의한 피해를 최소화하기 위해 전자어구실명제 실행계획을 발표하였다. 어구의 과다사용 및 폐어구 저감을 위해 어구의 종류 및 위치, 사용자의 실명을 포함한 정보를 IoT 기반의 통신을 이용하여 어선 및 관제센터에 효율적으로 전송할 수 있는 기술이 필요하다. 본 논문에서는 전자어구실명제를 실행하기 위한 LoRa 기반의 부이 장착 단말 장치와 어선용 게이트웨이를 제안한다. SEMTECH사의 SX1276 칩 사양과 ISM 대역인 900 MHz 대역을 사용하여 1(게이트웨이):200(부이) 통신이 가능하도록 설계하고 제작하였다. 또한 전자어구실명제 실행의 기술적 제안으로써의 실증을 위해 해상 시험 결과를 분석하였다.

• 한국전자파학회논문지
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• 제17권4호
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• pp.380-386
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• 2006

CPW(Co-Planer Waveguide) 전송선을 이용하여 자동차 연료 게이지 시스템인 전자식 연료 센더를 개발 제작하였다. 전송선 주위의 물질에 따라 전송선의 특성 임피던스가 변화되는 특성을 이용하였다. 자동차 연료통 속의 휘발유 혹은 경유의 높이에 따라 전송선의 특성 임피던스가 변화하면 반사량이 달라지므로 반사된 전압을 증폭함으로써 기존의 기계식 장치를 대체하는 시스템을 제작하였다. 브이(buoy)에 의한 부력과 연동된 저항 변화를 이용한 기존의 floating 방식이 갖는 기계식 작동 고장을 없애고, 유량 높이 오차를 줄이도록 하였다. 두께 1.6 mm의 Epoxy 기판에 CPW 전송 선로 및 제반 전자 장치를 구성하여 실측한 결과 기존 시스템에 비해 높이 오차가 적고 선형성이 우수한 특성을 보였다. 이 시스템은 PCB상 SMT로 제작되어 저가이면서도 양산성이 좋고 수명이 반영구적이어서 기존 시스템과의 경쟁력에서 우위를 보일 것으로 예상된다.