• Journal of the Optical Society of Korea
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• v.14 no.2
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• pp.142-145
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• 2010

In this work, a numerical analysis of a CIGS ($CuIn_{1-x}Ga_xSe_2$) solar cell with a rectangular grating on the electrode is presented. The effects of the grating on the energy conversion efficiency are calculated using the RCWA (rigorous coupled wave analysis) method. In conventional CIGS solar cells, the thickness of the light absorption layer (CIGS) is $2\;{\mu}m$, at which the incident light is almost absorbed. By adopting a grating on the electrode and using a less than $1\;{\mu}m$ CIGS layer, we obtained a higher efficiency compared to the conventional solar cells.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.119.2-119.2
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• 2011

Dye-sensitized solar cells (DSSC) are currently attracting wide spread academic and commercial interest for the conversion of sunlight into electricity because of their easy manufacturing process and high efficiency. The solar energy conversion efficiencies of DSSC are strongly dependent on dye molecules adsorbed on the TiO2 surface which used for photosensitization of sun light, since an excited state of dye could inject an electron into the conduction band of semiconductor. We have developed novel organic dyes which have phenothiazine moieties as an electron donor in their charge-transfer chromophore for application of DSSCs. We had synthesized a series of phenothiazine derivatives which have different wave length absorbing chromophore in the molecule with high molar extinction coefficient. The photovoltaic performance of DSSC composed of organic chromophores with broad wavelength absorption property were measured and evaluated by comparison with that of pristine ruthenium dye.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.5
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• pp.82-91
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• 2014

The combined generator system by integrating several renewable energy sources can share the electrical infrastructure and therefore have the advantage of constructing not only the transmission system but also the power conversion system. Among the various combined renewable system, the wind power and wave power has a high possibility of future growth due to the economic feasibility in offshore environment. This kind of large-scale combined systems might be follow the determination by the transmission system operator's directions and control the output profile by focusing at PCC. However, both renewable energies are depend on the unpredictable environmental variation; it is needed to do the compensation devices. In this paper, the ESS compensation plan is proposed to do output determination of the combined generator system by paying attention to active power of utility grid with the analysis of the controllable elements of the wind and wave power generator. The improvement of the new application technique of the combined system is confirmed through using the PSCAD/EMTDC. The entire simulation process was designed by adopting the active power control according to the reference signal of TSO.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.2
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• pp.120-128
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• 2016

This paper describes power generation from sea waves by using linear permanent magnet generator. A buoy is placed on the ocean surface and connected to the generator. The wave energy is carried out from the movement of a buoy. An electrical conversion system is needed between the generator and the grid. For an analysis of the power system, the modeling of the linear generator and converter system was proceeded. This paper proposes vector control method for wave power generation system using linear generator. In order to verify the proposed method, simulation and experiment performed and the results support the validity of the control scheme.

• Journal of Ocean Engineering and Technology
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• v.26 no.3
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• pp.33-38
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• 2012

The aim of this experimental study was to analyze the effect of the shape parameters and chamber pressure of a land-based oscillating water column (OWC) in regular incident waves. The magnitude of the free surface elevations inside the chamber was measured in a two-dimensional wave tank for various chamber skirt drafts and bottom slope angles. The surface elevations were also measured under both open chamber and partially open chamber conditions. From these measurements, the optimum shape of the OWC device could be predicted for the maximum wave energy conversion efficiency. It was found that the resonance frequency of the OWC system associated with incident waves moved toward the long wave region with increments of the draft of the chamber skirt and bottom slope. The behavior of the free surface elevation inside the chamber was also found to be dependent on the chamber pressure.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.3
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• pp.249-257
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• 2013

This study newly presents a synthetic phase tuning technique to suppress the unwanted torsional mode while enhancing the desired torsional mode in a pipe. Specifically, we aim at the enhancement of the first torsional mode and the suppression of the undesired, second torsional mode. Earlier efforts were to enhance the desired wave mode only in the hope that the enhancement results in the suppression of the unwanted wave mode. Unlike these efforts, the suggested technique makes the complete cancellation of the unwanted wave mode but it is shown to enhance the desired first mode for torsional wave problems. In the present study, the synthetic phase tuning is developed for the cancellation of the unwanted wave mode, meaning that the number of necessary experimental equipments is reduced. Simulation and experiment were carried out to check the effectiveness of the proposed method. As an application of the suggested technique, we investigated the reflection and mode conversion characteristics of the first torsional mode according to the step thickness variation in a stepped pipe.

• Journal of Navigation and Port Research
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• v.37 no.6
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• pp.597-601
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• 2013

Recently, many studies about the wave power generation system for the marine structure as the hybrid form in linked with the original features have been made of. Of these, the wave power generation system using oscillating water column(OWC) has function to convert wave energy to electrical energy with original function of the break water structure. In this type of generation system, it is important to make the flow of sea water as much as possible without loss. Output characteristics of wave power generation system depending on entrance section were described in the paper. Also, flow quantity changing with entrance section, velocity of sea water and output of wells turbine were measured by simulating OWC wells turbine model in break water, one of the general marine structure. Finally, entrance section was suggested to enhance the energy conversion efficiency based on the results of simulation.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.235-240
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• 2004

This paper deals with the performance analysis of impulse turbine for owe type wave energy conversion device. Numerical analysis was performed using a commercially-available software FLUENT. This parametric study includes the variation of the setting angle of guide vane. Since parametric study at various flaw coefficients requires tremendous amounts of computing time, two-dimensional cascade flaw approximation was employed to find out optimum principal particulars in rather simple manner. Full three-dimensional calculation was also performed for several cases to confirm the validity of two-dimensional approach. Results were compared to other experimental data, for instance Setoguchi et al (2001)'s extensive set of data, and found to be well demonstrating the usefulness of 2-D analysis. Advantages and disadvantages of each method were also evaluated.

• Ocean Systems Engineering
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• v.3 no.4
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• pp.309-325
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• 2013

Ocean Thermal Energy Conversion (OTEC) systems utilize the temperature difference between the surface water and deep ocean water to generate electrical energy. In addition to ocean surface waves, wind and current, in certain locations like the Andaman Sea, Sulu Sea and the South China Sea the presence of strong internal waves may become a concern in floating OTEC system design. The current paper focuses on studying the dependence of the CWP hydrodynamic drag on relative velocity of the flow around the pipe, the effect of drag amplification due to vortex induced vibrations and the influence of internal waves on the floating semi and the cold water pipe integrated OTEC system. Two CWP sizes are modeled; the 4m diameter pipe represents a small scale prototype and the 10m diameter pipe represents a full commercial size CWP. are considered in the study.

• Journal of Ocean Engineering and Technology
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• v.21 no.5
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• pp.9-17
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• 2007

This paper deals with the design and analysis of a 250kW class impulse turbine for wave energy conversion. Numerical analysis was performed using FLUENT. The size and the performance of a turbine required to provide a certain power can be estimated using a series of performance charts built through the present study. Temporal and spatial variations of flaw fields were also considered and compared with those of uniform inflow. It was concluded that a simple steady-flow analysis using performance charts still provided a practical and useful way to predict the design and performance of turbines.