• Journal of Ocean Engineering and Technology
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• v.16 no.1
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• pp.58-63
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• 2002

In this research, a design guideline of current generating HAT rotor and acceptable field rotor in offshore environment is proposed. To design HAT rotor model, wind mill rotor design principles and turbine theories were applied based on a field HAT rotor experimental data. To verify the compatibility of the rotor design method and to analyze the properties of design factors, 3 rotor models were designed and experimented in a circular water channel. Three rotor models were designed according to different blade numbers and blade shapes. By changing flow velocity, rotor rpm, the rotor power and efficiency were measured and the properties of rotor were estimated. The results can be effectively applied to the design of current generation rotor.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.04a
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• pp.89-96
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• 1997

Most civil engineering structures, such as highway bridges, towers, power plants and offshore structures suffer structural damages over their service lives caused by adverse loading such as heavy transportation loads, machine vibrations, earthquakes, wind and wave forces. Especially, if excessive load would be acted on the structure, general or partial stiffness should be degraded suddenly and service lives should be shortened eventually For realistic damage assessment of these civil structures, System Identification method using only structure dynamic response data with unknown input excitation is required and thus becoming more challenging problem. In this paper, an improved Iterative Least Squares method is proposed, which seems to be very efficient and robust method, because only the dynamic response data such as acceleration, velocity and displacement is used without input data, and no information on the modal properties is required. The efficiency and robustness of the proposed method is proved by numerical problems and real single span beam model test.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.115-116
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• 2015

본 논문에서는 PSCAD/EMTDC 소프트웨어를 이용하여 3MVA 용량의 풍력발전기와 2.4MVA 용량의 파력발전기로 구성되어 있는 부유식 파력-해상풍력 연계형 발전시스템 모델을 모의 할 예정이다. 각각의 발전시스템은 발전기, 발전기 컨버터, 전력망 컨버터, 전력망으로 구성되어 있고 시뮬레이션 결과를 통해 각각의 풍력 및 파력발전기에서 전력망의 유효전력과 무효전력을 완전히 독립적으로 제어 할 수 있음에 대하여 살펴 볼 것이다.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.2
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• pp.163-171
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• 2020

A model test for assessment of towing stability and seakeeping of a multi-purpose mobile base (MMB) was performed in calm water and wave conditions. Scale ratio of the MMB was 1/48. Tension of the towing line was measured during tests to estimate effective power to tow the full scale MMB. The tests were repeated with towing speed. In addition, an inertial measurement unit was used to measure six DOF motion of the model. Seakeeping performance was assessed through the captive model test.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.5
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• pp.583-590
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• 2015

Submarine cable installation is essentials for grid connection between existing power grid and newly produced electricity which will be from offshore wind farm in Southwest sea area of Korea. Especially, submarine cable route and protection method is designed in order to ensure the economical efficiency, workability and stability of submarine cable installation. On this paper, we will give the basic information about the submarine cable route and protection method of offshore wind farm which will be built in Southwest sea area of Korea. For this, we have a numerical simulation at high and low tide based on the third-generation wave model SWAN(Simulating WAves Nearshore) using the long term wave data from Korea Institute of Ocean Science and Technology(KIOST). The results of the study, year mean Hs is 1.03m, Tz is 4.47s and dominant wave direction is NW and SSW When the incident wave direction is NW(Hs: 7.0 m, Tp: 11.76s), the distribution of shallow water design wave height Hs was calculated about 4.0~5.0m at high tide and 2.0~3.0m at low tide. When the incident wave direction is SSW(Hs: 5.84 m, Tp: 11.15s), the distribution of shallow water design wave height Hs was calculated about 3.5~4.5m at high tide and 1.5~2.5m at low tide. The wave direction on a dominant influence in the section of longitude UTM 249749~251349(about 1.6 km) and UTM 251549~267749(about 16.2 km) in the submarine cable route are each NW and SSW. Prominently, wave focusing phenomenon appears between Wi-do and Hawangdeung-do, in this sea area is showing a relatively high wave hight than the surrounding sea areas.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.1
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• pp.49-57
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• 2021

In the production power transmitting of a floating production system like a wind offshore floating, the power cable should be connected from the surface system into the subsea system. The connection between the surface and the subsea system will make the power cable get a dynamic load like current and wave forces. Based on this condition, a dynamic power cable is required to endure external physical force and vibration in the long-term condition. It needs more requirements than static power cable for mechanical fatigue properties to prevent failures during operations in marine environments where the external and internal loads work continuously. As a process to verify, the durability test of dynamic power cables under the marine operation environment condition was carried out by using domestic technology development.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.236.1-236.1
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• 2010

Due to global warming, the need to secure an alternative resource has become more important nationally. Due to the high tidal range of up to 9.7m on the west coast of Korea, numerous tidal current projects are being planned and constructed. The rotor, which initially converts the energy, is a very important component because it affects the efficiency of the entire system, and its performance is determined by various design variables. In this paper, a design guideline of current generating HAT rotor and acceptable field rotor in offshore environment is proposed. To design HAT rotor model, wind mill rotor design principles and turbine theories were applied based on a field HAT rotor experimental data. To verify the compatibility of the rotor design method and to analyze the properties of design factors, 3D CFD model was designed and analysed by ANSYS CFX. The analysis results and findings are summarized in the paper.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.3100-3111
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• 2021

Numerical modeling for the safety-related equipment used in a nuclear power plant (i.e., cabinet facilities) plays an essential role in seismic risk assessment. A full finite element model is often time-consuming for nonlinear time history analysis due to its computational modeling complexity. Thus, this study aims to generate a simplified model that can capture the nonlinear behavior of the electrical cabinet. Accordingly, the distributed plasticity approach was utilized to examine the stiffness-degradation effect caused by the local buckling of the structure. The inherent dynamic characteristics of the numerical model were validated against the experimental test. The outcomes indicate that the proposed model can adequately represent the significant behavior of the structure, and it is preferred in practice to perform the nonlinear analysis of the cabinet. Further investigations were carried out to evaluate the seismic behavior of the cabinet under the influence of the constitutive law of material models. Three available models in OpenSees (i.e., linear, bilinear, and Giuffre-Menegotto-Pinto (GMP) model) were considered to provide an enhanced understating of the seismic responses of the cabinet. It was found that the material nonlinearity, which is the function of its smoothness, is the most effective parameter for the structural analysis of the cabinet. Also, it showed that implementing nonlinear models reduces the seismic response of the cabinet considerably in comparison with the linear model.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.21-29
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• 2014

This paper deals with the bonding characteristic of grouted joint connections of monopile support structures for offshore wind power facilities. For the integration of pile connection of wind power supporting structure, fiber reinforced high performance cementeous grout was developed and the ultimate compressive strength of it is 125MPa and the direct tensile strength is 7.5 MPa at 7 days. To assess the bond strength of grout filled in pile connection, small scaled direct bond tests under axially loaded was performed and analyzed according the existing guidelines. The fiber volume fraction (0%, 0.5% and 0.9%), aspect ratio of fiber (60 and 80) and the ratio of height to spacing of shear key (0.013 and 0.056) were adopted as the experimental variables. From the test results, the maximum bond strength among the all specimens was 30.8MPa and the bond strength of grouted connection was affected by the ratio of height to spacing of shear key than the fiber volume fraction.

• Journal of the Korean GEO-environmental Society
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• v.17 no.9
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• pp.5-12
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• 2016

Numerical analyses were carried out to simulate tilting control on the suction pile for offshore wind power embedded into cohesive soil and cohesionless soil using finite element software, ABAQUS. A 3-dimensional suction pile was modelled as a wished-in-place pile with $1^{\circ}$ tilted from vertical line. The inner room of suction pile was divided into 3 separate rooms for tilting control, and point load was applied to the center of gravity of a separate room to restore the original position of the suction pile. From numerical analyses, required suction pressure was obtained for desired tilting degree, and the maximum/minimum principle stresses of concrete skirt and the Mises stresses of inner steel wall were collected at original position. It was found that the required suction pressure was about 410 kPa for cohesive soil, and about 1,800 kPa for cohesionless soil.; likewise, obtained stresses were greater for cohesionless soil than cohesive soil.