• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.2
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• pp.145-152
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• 2012

As the problems of global warming are brought up recently, many skillful solutions for developing new renewable energy are suggested. One of the most remarkable things is ocean energy. Korea has abundant ocean energy resources owing to geographical characteristics surrounded by sea on three sides, thus the technology of commercialization about tidal current power, wave power is demanded. Especially, Tidal energy conversion system is a means of maintaining environment naturally. Tidal current generation is a form to produce electricity by installing rotors, generators to convert a horizontal flow generated by tidal current into rotating movement. According to rotor direction, a tidal current turbine is largely distinguished between horizontal and vertical axis shape. Power capacity depends on the section size crossing a rotor and tidal current speed. We therefore investigated three dimensional flow analysis and performance evaluation using commercial ANSYS-CFX code for an 100 kW class horizontal axis turbine for low water level. Then We also studied three dimensional flow characteristics of a rotating rotor and blade surface streamlines around a rotor. As a result, We found that torque increased with TSR, the maximum torque occurred at TSR 3.77 and torque decreased even though TSR increased. Moreover we could get power coefficient 0.38 at designed flow velocity.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.1
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• pp.9-16
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• 2019

Flow velocity changes in the shroud system for tidal current power generation due to experimental flow velocities and blade geometry changes were analyzed by hydraulic experiment and numerical simulation. Through the hydraulic experiment, flow velocities at inlet of shroud system and RPM according to blade geometry were measured, and numerical simulation was used to analyze flow velocity changes in shroud. When the experimental flow velocity was increased by about 28% and the shape of the airfoil was applied, the measured flow velocity at the shroud inlet tended to increase by up to about 56%. On the other hand, when airfoil-shaped blades were installed, the flow velocity at the inlet tended to increase by up to 14% compared to conventional blades, and RPM was also the highest at the same conditions. The hydraulic experiment and numerical simulation results showed an error of about 13%, and the trends of the flow velocity changes in each result are similar. Numerical simulation of the flow velocity changes in the shroud showed that the flow velocity tended to increase 1.7 times at the front of the blade compared to the inlet. The results of the flow velocity change analysis in the shroud system obtained from this study will provide the basic data necessary for the development of efficient shroud system for tidal current power generation.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.3
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• pp.22-35
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• 2011

Incheon Bay has a suitable condition for tidal power generation due to the high tidal range by topographical effect. Therefore a study on the technology development for tidal energy utilization has been promoted since 2006. It is needed to deduce optimal alternatives to determine the suitable location of facilities for tidal power generation and to reduce the environmental damage from development. In order to carry out efficiently this mission, spatial information system is essential to manage and use various spacial elements related to the development and conservation. In this study, for the development of tidal energy, spatial data could be defined as three kinds of dataset. Fundamental dataset is defined as spatial data such as tide, tidal current, wave, erosion and sedimentation. Framework dataset is composed of topographical map, facility map and bathymetry. The reference dataset is composed of marine ecology and environment having the characteristics of thematic map. This study is mainly aimed at establishing methodology of conceptual spatial data modeling classifying as essential data model and optional data model through the definition of the components of spatial data.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.121-124
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• 2006

국내외에 아직 적용 실적이 없는 발전소의 해수방류수를 이용한 조류식발전시스템의 개발을 위하여 하동화력발전소 방수로에 시험용 조류식 발전시스템을 설계 및 제작하여 현장시험이 진행 중이며, 이를 확장하여 상업용 발전을 위한 총 개발 규모를 산정하고 경제성을 분석하였다. 조류식발전구조물의 형상 설계, 가이드 베인을 이용한 출력 조정을 통하여 방수로의 수류상태를 적절히 조절하여 설계하는 것이 가능할 것으로 판단되며, 조류식발전구조물 설치시 방수로의 수류특성 수치계산 결과로 판단할 때 발전출력에 의한 에너지 회수뿐만 아니라 조류식발전구조물의 단면축소 효과 및 수두손실이 방수로의 수위 변화에 상당한 규모로 영향을 주고 있음을 확인하였다. 조류식발전구조물 설치 이전의 유속 관측 결과를 이용하여 발전량을 산정한 경우 소수력발전 단가 적응시 경제성이 떨어지지만, 조류식발전시스템의 설치시 유속 증가 효과가 나타날 뿐만 아니라 가이드 베인 등을 이용하여 발전량 증대를 꾀하면 충분한 경제성을 확보할 수 있는 조류식발전시스템의 설치가 가능할 것으로 판단된다.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.509-512
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• 2006

국내 대형 기력발전단지에서 냉각수로 사용되고 방류되는 해수는 약 150cms로 (100Mwe 당 약 5cms) 약 3,000kW 이상의 수력에너지를 보유하고 있으나, 현재 활용되지 못하고 그대로 해양으로 방류되고 있다. 발전소 방수로는 흐름조건이 비교적 균일하고, 파랑 내습이 없으며 부유사 해조류, 부유물 충돌 등의 문제가 발생하지 않아 자연 해양조건보다 조류력 발전에 매우 유리하나 수심이 낮고, 순환수 계통에의 영향으로 다수의 수차를 설치하기는 어려운 조건을 지니고 있다. 따라서, 인공수로의 균일하고 양호한 흐름조건에 적합한 보다 경제적인 수차를 개발하고, 발전량을 증대하기 위한 수차 배치 기술, 수차 및 발전기 지지구조물의 설계 기술, 계통 연결기술 등을 개발할 필요가 있으며, 이를 위하여 시험용 조류식 발전시스템을 제작하여 수차의 성능 및 전체 발전시스템의 성능을 평가하여 발생되는 문제점을 해결하고자 한다. 본 연구에서는 시험용 조류식 발전시스템을 하동화력발전소 방수로에 적용하기 위하여 현장 특성 분석, 형식 선정, 발전량 산정 등의 시스템 설계를 수행하였다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.1
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• pp.48-54
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• 2020

Numerical analysis was carried out to analyze the flow fields and mechanical output of a rotor for various positions and inlet flow rates in a shroud, and it was compared with experimental data. Rotor and seawater current largely affects the flow field characteristics in the shroud system. Especially the mechanical output of the rotor increased with axial position near the center of the cylinder, and it gradually decreased close to the entrance and exit. Also, the rotor output increased with the inlet velocity. Axial and angular momentum of flow along the cylinder region rapidly increased and reached a peak, and then decreased as it passed through the rotor, while there was no significant change in the cylinder region. It is expected that these results can be used as applicable design data for the development of the tidal power generation system.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.1355-1355
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• 2005

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.5
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• pp.314-319
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• 2019

The numerical simulation method was used to analyze the flow velocity change and mechanical coefficient characteristics of the blade in the shroud system that changes with the initial flow velocity and the blade rpm. In the analysis condition, the initial flow velocity was varied from 0.35 m/s to 1.0 m/s, and the blade rpm varied from 50 rpm to 300 rpm. Through this, the mechanical coefficient was estimated. The flow velocity changes tended to increase more than 1.8 times at the middle point compared to the inlet. When the flow velocity ratio was 0.75 m/s compared to the initial flow velocity of 0.5 m/s, the flow velocity ratio decreased. The mechanical coefficient using the torque of the blade also showed the highest coefficient at 0.5 m/s, and the trends were similar. On the other hand, the maximum coefficient was estimated to be about 20.88% in TSR 4.77 when the initial flow velocity was 0.5 m/s. The mechanical coefficient analysis of blades in this study is expected to provide the basic data for hydraulic model experimental.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.56-61
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• 2009

Paradigm depending only on fossil fuel for building heat source is rapidly changing. Accelerating the change, as it has been known, is obligation for reducing green house gas coming from use of fossil fuel, i.e. reaction to United Nations Framework Convention on Climate Change. In addition, factors such as high oil price, unstable supply, weapon of petroleum and oil peak, by replacing fossil fuel, contributes to advance of environmental friendly renewable energy which can be continuously reusable. Therefore, current new energy policies, beyond enhancing effectiveness of heat using equipments, are to make best efforts for national competitiveness. Our country supports 11 areas for new renewable energy including sun light, solar heat and wind power. Among those areas, ocean thermal energy specifies tidal power generation using tide of sea, wave and temperature differences, wave power generation and thermal power generation. But heat use of heat source from sea water itself has been excluded as non-utilized energy. In the future, sea water heat source which has not been used so far will be required to be specified as new renewable energy. This research is to survey local heating system in Europe using sea water, central solar heating plants, seasonal thermal energy store and to analyze large scale central solar heating plants in German. Seasonal thermal energy store necessarily need to be equipped with large scale thermal energy store. Currently operating central solar heating system is a effective method which significantly enhances sharing rate of solar heat in a way that stores excessive heat generating in summer and then replenish insufficient heat for winter. Construction cost for this system is primarily dependent on large scale seasonal heat store and this high priced heat store merely plays its role once per year. Since our country is faced with 3 directional sea, active research and development for using sea water heat as cooling and heating heat source is required for seashore villages and building units. This research suggests how to utilize new energy in a way that stores cooling heat of sea water into seasonal thermal energy store when temperature of sea water is its lowest temperature in February based on West Sea and then uses it as cooling heat source when cooling is necessary. Since this method utilizes seasonal thermal energy store from existing central solar heating plant for heating and cooling purpose respectively twice per year maximizing energy efficiency by achieving 2 seasonal thermal energy store, active research and development is necessarily required for the future.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.10
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• pp.1532-1539
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• 2017

The floating photovoltaic system is a new concept in the renewable energy technology. That is similar to land based photovoltaic technology except floating system. So the system needs buoyant objects, mooring, ect, besides modules and supports, and that is able to withstand in water level changes and wind strength. Therefore the floating photovoltaic system is much different from land photovoltaic system. K-water (Korea Water Resources Corporation) has been operating two floating photovoltaic system that's capacity is 100 kW and 500 kW respectively since in summer 2011 for commercial generation, and have construction project for 2,000 kW in Boryeong multipurpose Dam and other areas. Furthermore K-water was developing a tracking-type floating photovoltaic system at Daecheong multipurpose Dam and developed and installed an ocean floating photovoltaic demonstration plant at Sihwa Lake in October 2013 for R&D. In this paper, we introduce that structure of floating photovoltaic system include buoyant structure, mooring system and auxiliary device. Especially the rope which is in part of mooring should be always maintain tension under any water level. Also we explain about structure design concept to wind load in an every loading condition and a kind of structure materials and PV structure types used in water environment. Especially ocean floating PV system is affected by tidal current and typhoon. So there are considering the elements in design. Finally we compare with floating and land photovoltaic on power amount. As a result of that we verified the floating photovoltaic system is more about 6.6~14.2 % efficiency than a general land photovoltaic system.