• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.7
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• pp.40-50
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• 2005

In this paper, preliminary results for performance prediction of a dual-rotor wind turbine generator system are presented. Blade element and momentum theories are used to model the aerodynamic forces and moments acting on the rotor blades, and multi-body dynamics approach is used to integrate the major components to represent the overall system. Not only the steady-state performance but the transient response characteristics are analyzed. Pitch control strategy to control the rotor speed and the generator output is proposed and its performance is verified through the nonlinear simulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.6
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• pp.87-95
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• 2004

In this paper, an efficient method for modeling a dual-rotor type wind turbine generator system and simulation results are presented. The wind turbine is treated as a collection of several rigid bodies, each of which represents, respectively, main and auxiliary rotor blades, high/low speed shafts, generator, and gear system. Simulation software WINSIM is developed to implement the proposed modeling method and is used to investigate the transient and steady-state performance of the wind turbine system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1275-1282
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• 2012

Helicopter rotor systems are dynamically loaded structures with many composite components such as the main and the tail rotor blades. The fatigue properties of composite materials are extremely important to design durable and reliable helicopter rotor blades. The safe-life methodology has generally been used in the helicopter industry to substantiate dynamically loaded composite components. However, it cannot be used to evaluate the strength reducing effects of flaws and defects that may occur during manufacturing and operational usage. The damage tolerance methodology provides a proper means to overcome this shortcoming; however, it is difficult to economically apply it to every composite component. The flaw tolerant methodology is an equivalent option to the damage tolerance methodology for civil and military rotorcraft. In this study, the flaw tolerant safe-life evaluation is described and illustrated by means of successful application to substantiate the retirement time of composite rotor blades.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.12
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• pp.25-34
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• 2006

In this paper, a method of designing the pitch control algorithm for the wind turbine generator system (WTGS) and results of nonlinear simulation are presented. For this, the WTGS is treated as a multibody system and the blade element and momentum theory are adopted to model the aerodynamic force and torque acting the rotor blades. For the purpose of controller design, the WTGS is approximated to 1 DOF system using the fact that the WTGS is eventually a constrained multibody system. Then a classical PID controller is designed and used to regulate the rotational speed of the generator. FORTRAN based nonlinear simulation program is written and used to evaluate the performance of the proposed controller at the various wind scenario and operational modes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.2
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• pp.111-118
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• 2022

An electro-mechanical actuator (EMA) is an actuator that combines an electric motor with a mechanical power transmission elements, and it is suitable for urban air mobility (UAM) in terms of design freedom and maintenance. In this paper, the author presents the research results of the EMA that controls the rotor blade pitch angle of UAM. The actuator is based on an inverted roller screw and controls the blade pitch angle through a two-bar linkage. The dynamic equations for the actuator alone and the blade pitching motion with actuator were derived. For the latter, the equivalent moment of inertia is variable depending on the link angle due to the two-bar linkage. The variations of the equivalent moments of inertia are analyzed and compared in terms of the nut motion and the blade pitch motion. For an example model, the variation of the equivalent moment of inertia of the former is smaller than the latter, so it is judged that the dynamic equations derived from the point of view of the nut motion is suitable for the controller design.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.2
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• pp.156-162
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• 2008

The static aeroelastic analysis of composite hingeless rotor blades in hover was performed using free-wake method. Large deflection beam theory was applied to analyze blade motions as a one-dimension beam. Anisotropic beam theory was applied to perform a cross-sectional analysis for composite rotor blades. Aerodynamic loads were calculated through a three-dimensional aerodynamic model which is based on the unsteady vortex lattice method. The wake geometry in hover was described using a time-marching free-wake method. Numerical results of the steady-state deflections for the composite hingeless rotor blades were presented and compared with those results based on two-dimensional quasi-steady strip theory and prescribed wake method. It was shown that wakes affect the steady-state deflections.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.4
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• pp.289-309
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• 2014

A rotor blade is an important device that converts kinetic energy of wind into mechanical energy. Rotor blades affect the power performance, energy conversion efficiency, and loading and dynamic stability of wind turbines. Therefore, considering the characteristics of a wind turbine system is important for achieving optimal blade design. This study examined the general blade design procedure for a wind turbine system and aero-structure design results for a 2-MW class wind turbine blade (KR40.1b). As suggested above, a rotor blade cannot be designed independently, because its ultimate and fatigue loads are highly dependent on system operating conditions. Thus, a reference 2-MW wind turbine system was also developed for the system integrated load calculations. All calculations were performed in accordance with IEC 61400-1 and the KR guidelines for wind turbines.

• Aerospace Engineering and Technology
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• v.3 no.2
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• pp.50-55
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• 2004

Performance predictions of the propulsion system were conducted for a 900㎏ class Canard Rotor/Wing vehicle. The main components of the propulsion system are turbojet engine, exhaust ducts and nozzles. The internal flow of the duct was considered as one-dimensional, compressible and viscous flow. Adequate governing equations including centrifugal force effect were applied to the analysis of the duct flows. Results such as available power, available thrust, engine throttle, mass flow rates, rotor RPM and cruise nozzle area were presented for rotary-wing mode and transition mode.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.648-653
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• 2007

In this study, we have generated fatigue load spectrum that is using to prediction of life time for the helicopter rotor blades. We derive utility helicopter missions for the sake of generating load spectrum. Helix and Felix are standard loading sequences which relate to the main rotors of helicopters with articulated and semi-rigid rotors respectively. We got scale factors which is applied to specific case and it did be obtained through the finite element analysis tools. The fatigue life of the rotor blade is estimated by using MSC/Fatigue. We suggest that generated our fatigue load spectrum in conjunction with small utility helicopter should use to rotor blade fatigue test of the korea helicopter program.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.186-186
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• 2010

개별 블레이드 피치 제어(individual blade pitch control)는 각각의 로터 블레이드의 피치각을 독립적으로 조정함으로써 블레이드에 작용하는 공력을 변화시키는 원리로 풍력 터빈 구조물에 발생하는 동적 피로하중을 저감시키기 위한 제어기법이다. 그러나 개별 피치 제어에 의해 발생하는 각 블레이드의 독립적인 피치 운동은 풍력 터빈 회전자에 비대칭성을 야기하고 구조물의 동적 불안정 현상을 발생시킬 수 있기 때문에 이에 대한 정확한 동적 해석이 선행되어야 한다. 하지만 블레이드의 피치 운동이 반영된 풍력 터빈은 시변계로 간주되어 기존의 시불변계 해석기법을 직접 적용할 수 없기 때문에 동적 해석에 어려움이 있다. 이 논문에서는 각각의 블레이드 피치운동을 주기함수로 근사화 함으로써 풍력 터빈을 주기 시변계로 모형화한다. 그리고 효율적으로 주기 시변계의 근사해를 구하기 위한 변조 좌표 변환(modulated coordinate transformation)기법을 적용하여 블레이드의 피치운동이 반영된 풍력 터빈의 동적 안정성 해석을 수행하였다. 그리고 현재 풍력 터빈의 동적 해석에 활용되는 대표적인 해석 기법인 다중 블레이드 좌표변환(multi-blade coordinate transformation)기법을 이용한 해석보다 정확한 결과를 얻을 수 있음을 보였다.