• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.41.2-41.2
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• 2011

NREL NWTC Deside codes are analyzed and introduced to develop the system performance simulation program for wind turbine generator systems. In this paper, The AirfoilPrep generating the airfoil data, the IECWind generating hub-height wind data with extreme condition following IEC 61400-1, the TurbSim generating stochastic full-field turbulent wind data, the PreComp calculating structural and dynamic properties of composite blade and the BModes making mode shapes of blade and tower are explained respectively.

• Wind and Structures
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• 제7권1호
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• pp.41-54
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• 2004

An analysis refinement of the Messina Strait suspension bridge project has been recently required, concerning mainly the yaw angle effects on the multi-box deck section aerodynamics and the vortex shedding at low reduced velocities $V^*$. In particular the possible interaction of the axial flow with the large cross beams has been investigated. An original test rig has been designed at this purpose allowing for both forced motion and free motion aero elastic tests, varying the average angle of attack ${\alpha}$ and the deck yaw angle ${\beta}$. The hydraulic driven test rig allowed for both dynamic and stationary tests so that both the stationary coefficients and the flutter derivatives have been evaluated for each yaw angle. Specific free motion tests, taking advantage from the aeroelastic features of the section model, allowed also the study of the vortex shedding induced phenomena.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권1호
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• pp.7-14
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• 2014

Aircraft variable frequency power and a new application of induction motor under the aero-power are introduced. The transient models and simulation of induction motor are reviewed. A new transient model and simulation method is presented that includes deep-bar effect and magnetic saturation. Dynamic magnetizing inductance, rotor resistance and leakage reactance are considered as varying parameters in state-space model. Base on known rotor structure and speed, these parameters can be calculated.

• 한국군사과학기술학회지
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• 제2권2호
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• pp.70-82
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• 1999

During the aircraft conceptual design stage, rapid aerodynamic analyses over various configurations are required. Hence, empirical and analytical methods play important roles in predicting the aero-dynamic characteristics. In this study, total drag estimation method based on empirical and analytical approaches is developed. By comparing with the results of the wind tunnel experiment and existing prediction methods, it is demonstrated that the developed method is accurate and useful in predicting total drag for the whole Mach number range.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.209-214
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• 2009

In this research, an external noise distribution of a HST has been analyzed by using a ray tracing techniques. An aero-dynamic noise generated from a bogie has been considered as a major noise source. Then a distribution of the noise on the outside of the vehicle is calculated using a ray noise technique. The models simulated are two different acoustic fields: an open field and a tunnel. In order to evaluate the noise effects, an exterior structure has been modified by using a different length of skirts. Various application schemes of reducing an environmental noise level will be expected for a HST based on this research.

• 항공우주시스템공학회지
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• 제11권6호
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• pp.84-91
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• 2017

덕트 팬의 정지 비행시 동특성에 관한 연구를 수행하였다. 팬에 적용되는 블레이드에 대해서 단면 모델링을 수행하였으며, 로터 시스템의 구성요소들을 고려하여 해석 모델을 구축하였다. 로터의 회전수 및 피치각 조건에 따른 동특성 해석을 수행하였으며, 해석 결과 제안된 덕트 팬 시스템은 설계 운용범위 내에서 진동 증가와 같은 공탄성학적 불안정성이 적음을 확인하였다. 해석 절차의 검증을 위해 실제덕트 팬 회전 시험장치를 구성하였다. 기능 시험을 수행하여 덕트 팬 시험장치의 구성품간 거동 및 간섭 여부를 확인하였다. 동특성 시험을 위해 유압가진기를 사용하여 콜렉티브 가진을 하였으며, 비회전/회전시 블레이드의 고유진동수를 측정하였다. 시험 결과와 해석 결과의 비교를 통해 시험 장치와 해석 모델간의 상관관계가 잘 정립되어 있음을 확인하였다.

• 한국소음진동공학회논문집
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• 제11권7호
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• pp.253-260
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• 2001

A Study of interior noise reduction in the magelv train is presented. Tarin speed of interest is low such that aero-dynamic noise is negligible and power supply system is a dominant noise source. Based on the measurements of interior noise and acceleration levels during running and zero speed conditions, dominant noise sources are identified. After spectra characteristics of noise sources are investigated several noise reducing methods are studied such as STL increasement of floor panels. sealing. and absorption treatment It is found that the most important noise sources are VVVF inverter and SLM in running condition, whereas air conditioner and DC/DC converter are dominant in zero speed. Sine the major noise sources are under the floor complete sealing and high STL of the floor panel are shown to be the most crucial factors in noise reduction After sound absorbing material, which is polyurethan foam of 50 mm thickness, is thickness, is attached to the downward side of the floor in addition to sealing treatment, the interior noise is reduced by 3~4 dB.

• International Journal of Ocean System Engineering
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• 제1권2호
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• pp.110-119
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• 2011

Numerical and experimental studies were performed to investigate the aerodynamic performance of a thin wing in close vicinity to the ground. The vortex lattice method (VLM) was utilized to simulate the wing in ground (WIG) effect, which included freely deforming wake elements. The numerical results acquired through the VLM were compared to the experimental results. The experiment entailed varying the ground clearance using the DHMTU (Department of Hydromechanics of the Marine Technical University of Saint Petersburg) wing and the WIG craft model in the wind tunnel. The aero-dynamic influence of the design parameters, such as angles of attack, aspect ratios, taper ratios, and sweep angles were studied and compared between the numerical and experimental results associated with the WIG craft. Both numerical and experimental results suggested that the endplate augments the WIG effect for a small ground clearance. In addition, the vortex lattice method simulated the wake deformation following the wing in the influence of the ground effect.

• Journal of Mechanical Science and Technology
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• 제18권2호
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• pp.272-285
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• 2004

The losses at off-design points from a compressor cascade occur due to the deviation from a design incidence angle at the inlet of the cascade. The self-noise from the blade cascade at off-design points comes from a separated boundary layer and vortex sheddings. If the incidence angle to the cascade increases, stalling in blades may occur and the noise level increases significantly. This study applied Large-Eddy Simulations (LES) using deductive and deductive dynamic SGS models to low Mach-number, turbulent flow with each incidence angle to the cascade ranging from -40$^{\circ}$ to +20$^{\circ}$ and compared numerical predictions with measured data. It was observed that the oscillating separation bubbles attached to the suction surface do not modify wake flows dynamically for cases of negative incidence angles. However, an incidence angle greater than 8$^{\circ}$ caused a separated vortex near the leading edge to be shed downstream and created stalling. The computed performance parameters such as drag coefficient and total pressure loss coefficient showed good agreement with experimental results. Noise from the cascade of the compressor is summarized as sound generated by a structure interacting with unsteady, turbulent flows. The hybrid method using acoustic analogy was observed to closely predict the measured overall sound powers and directivity patterns at design and off-design points of blade cascade.

• 한국항공우주학회지
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• 제40권7호
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• pp.564-573
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• 2012

새롭게 제안된 공력 설계 절차와 In-house 프로그램을 이용하여 1 MW급 수평축풍력 터빈 블레이드의 형상을 결정하였고, 기존에 개발된 블레이드의 실험 결과와 본 연구에서 제안한 블레이드와의 비교를 통하여 공력 설계에 대한 타당성을 제시하였다. 블레이드의 구조 설계는 Netting Rule과 Rule of Mixture를 적용하여 설계를 진행하였다. 설계된 블레이드의 구조적 안전성은 상업적 유한요소프로그램인 MSC.NASTRAN을 사용하여 다양한 하중에 따라 선형 정적해석, 변형해석, 좌굴해석, 진동모드해석 등을 수행하였다. 최종적으로 Spera가 제시한 실험식을 적용하여 요구된 피로수명에 대해 타당성을 확인하였다.