• Journal of Advanced Marine Engineering and Technology
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• 제35권6호
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• pp.835-841
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• 2011

해상에서 운영되는 해양 시설물용 파력 발전시스템은 대용량 계통 연계형으로 개발되어 왔다. 그러나 등부표용 파력 발전시스템에는 소용량의 발전시스템이 운영 측면에서 효과적이다. 소형 파력 발전의 경우 단순히 전파 정류하여 축전지에 충전하는 방식(직결 방식)을 주로 사용한다. 본 논문에서는 소형 웰스터빈의 발전 특성을 고려하여 부스터 컨버터 기반의 파력 발전전력제어기를 개발하였다. 직결 방식과 부스터 컨버터 방식의 제어기를 설계하고, 실험을 통하여 그 특성을 비교하였다. 실험 결과 제안하는 제어기가 발전기의 출력전압이 낮은 구간에서 출력특성이 개선되었다.

• Journal of information and communication convergence engineering
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• 제7권1호
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• pp.46-51
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• 2009

In this paper, the two-axis theory is adopted to analyze the secondary excited induction generator applied to random wave input generation system. The analysis by the two-axis theory helps to know the transmitted power of the induction machine. The electric variables, like as primary and secondary currents, voltages, and electric output power, were able to express as equations. These equations are help to simulate the generation system numerical model and to know the transient state of the system. As it is preferred to stabilize the output voltage and frequency in the constant level, microcomputer controlled VSI connected to the secondary windings supplies the secondary current with slip frequency. For testing the appropriateness of this method, the input torque simulator in the laboratory to drive the secondary excited results show the advantage of secondary excited induction generator system for the random input wave generation system.

• 한국항해항만학회지
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• 제33권7호
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• pp.501-504
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• 2009

There are many difficulties to supply constant power to marine facilities which operate in the sea. Especially, there is a limit to stand alone power supply systems due to the influence of weather conditions. That's why a hybrid power supply system is required to overcome these problems. This paper will describe an Electronic Anti-Fouling System (EAFS) to maximise the power efficiency for a solar - wave hybrid power generation system. A main factor reducing the efficiency of a Wave Energy Converter (WEC) is due to the attachment of aquatic life forms. Therefore the aim of this research is to develop a simulation programme to enable the design of more efficient EAFS for hybrid power generation systems and to provide valuable data for production of more efficient EAFS.

• 한국산업융합학회 논문집
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• 제26권3호
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• pp.401-409
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• 2023

Oscillating water column (OWC) type wave power generator system is a power generation system that uses wave energy, a sustainable and renewable energy source. Irregular cycles and wave heights act as factors that make it difficult to secure generation efficiency of the wave power generator system. Recently, research for improving power generation efficiency is being conducted by applying digital twin technology to OWC type wave energy converter system. However, digital twin using sensor data can predict erroneous performance due to uncertainty in the sensor data. Therefore, this study proposes an uncertainty analysis method for sensor data which is used in digital twin to secure the reliability of digital twin prediction results. Uncertainty quantification considering sensor data characteristics and future uncertainty information according to uncertainty propagation were derived mathematically, and confidence interval estimation was performed based on the proposed method.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.615-619
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• 2009

This paper is investigated to variation of wave power generation operation rate, operating capacity and output with the wave conditions represented by wave height-period window. By the use of the long-term wave data from 1979 to 2002 which is provided by Korea Ocean Research & Development Institute(KORDI), we calculated the monthly variation of significant wave height(Hs), zero-up crossing period(Tz) and distribution of wave appearance rate. And using the same wave data, it was charted the Hs-Tz and wave-energy scatter diagrams.

• Journal of information and communication convergence engineering
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• 제5권3호
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• pp.223-228
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• 2007

This paper deals with the secondary excited induction generator applied to random wave input generation system. As it is preferred to stabilize the output voltage and frequency in the constant level, microcomputer controlled CSI connected to the secondary windings supplies the secondary current with slip frequency. For testing this method, the input torque simulator is constructed, according to the power flow analysis. The experimental and numerical results show the advantage of secondary excited induction generator system for the random input wave generation system.

• 신재생에너지
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• 제7권4호
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• pp.37-41
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• 2011

This paper presents a Combined solar-wave Power Generation (CPG) concept that the CPG unit is maintained as buoyant at the level of sea water and it is also supported by a submerged tunnel, with the aim of supplying emergency electric power during the station blackout events of nuclear power plants. The CPG concept has been motivated from the 2011 Fukushima-Daiichi Accidents due to the loss of both offsite AC power and emergency diesel power caused by natural hazards such as earthquake and tsunami. The CPG is conceptualized by applying different types and different sites for emergency power generation, in order to reduce common cause failures of emergency power suppliers due to natural hazards. Thus, the CPG can provide a new mean for supplying emergency electric power during station blackout events of nuclear power plants. For this application, the CPG requirements are described with a typical configuration at the ocean side of a submerged tunnel.

• 한국유체기계학회 논문집
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• 제11권3호
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• pp.22-29
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• 2008

Clean and renewable energy technologies using ocean energy give us non-polluting alternatives to fossil and nuclear-fueled power plants to meet establishment of countermeasures against the global warming and growing demand for electrical energy. Among the ocean energy resources, wave power takes a growing interest because of its enormous amount of potential energy in the world. Therefore, various types of wave power conversion system to capture the energy of ocean waves have been developed. However, suitable turbine type is not normalized yet because of relatively low efficiency of the turbine systems. The purpose of this study is to investigate the internal flow and performance characteristics of a cross-flow type hydro turbine, which will be built in a caisson for wave power generation. Numerical simulation using a commercial CFD code is conducted to clarify the effects of the turbine rotation speed and flow rate variation on the turbine characteristics. The results show that the output power of the cross-flow type hydro turbine with symmetric nozzle shape is obtained mainly from Stage 2. Turbine inlet configuration should be designed to obtain large amount of flow rate because the static pressure and absolute tangential velocity are influenced considerably by inlet flow rate.

• Current Optics and Photonics
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• 제2권3호
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• pp.261-268
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• 2018

Stimulated polariton scattering (SPS) from the $A_1$ transverse optical (TO) modes of $BaTiO_3$ bulk crystal generating a terahertz (THz) wave with the noncollinear phase-matching (NPM) condition is theoretically investigated. To our best knowledge, this is the first report on THz wave generation from $BaTiO_3$ bulk crystal via SPS. Phase-matching (PM) characteristics in the NPM configuration are analyzed. Effective parametric gain lengths for the Stokes and THz waves in the NPM configuration are calculated. The effective parametric gain coefficient and absorption coefficient of the THz wave in $BaTiO_3$ are theoretically simulated. The THz phonon flux densities generated via SPS in $BaTiO_3$ are theoretically calculated by solving the coupled wave equations under the NPM condition. The PM characteristics and THz-wave parametric gain characteristics in $BaTiO_3$ are compared to those in $MgO:LiNbO_3$. The results of the analysis indicate that $BaTiO_3$ is an attractive optical crystal for efficient THz wave generation via SPS.

• 한국산업융합학회 논문집
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• 제23권6_2호
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• pp.999-1006
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• 2020

This study was conducted to develop an efficiency prediction program of a hydraulic secondary energy converter for calculating annual power generation of a Wavestar type wave power generator. Using the period and wave height obtained from the frequency domain analysis, the behavior of the floating body was obtained by assuming the sin function. The piston displacement and speed of the hydraulic cylinder were calculated considering the behavior of the floating body and the shape of the mechanism. The numerical simulation of the hydraulic system was performed by physically modeling the hydraulic cylinders, check valves, hydraulic motors, which are the main devices. In the future, this analysis program will be used to develop a program for estimating annual power generation of a moveable body type wave power generation device.