• Proceedings of the KSME Conference
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• 2002.08a
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• pp.795-798
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• 2002

This paper dispicts the vortical flow characteristics over a delta wing using a computational analysis for the purpose of investigating and visualizing the effect of the angle of attack and fee stream velocity on the low-speed delta wing aerodynamics. Computations are applied to the full, 3-dimensional, compressible, Navier-Stokes Equations. In computations, the free stream velocity is changed between 20m/s and 60m/s and the angle of attack of the delta wing is changed between $16^{\circ}\;and\;28^{\circ}$. For the correct prediction of the major features associated with the delta wing vortex flows, various turbulence models are tested. The standard $k-{\varepsilon}$ turbulence model predict well the vertical flows over the delta wing. Computational results are compared with the previous experimental ones. It is found that the present CFD results predict the vortical flow characteristics over the delta wing, and with an increase in the free steam velocity, the leading edge vortex moves outboard and its streangth is increased.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.1
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• pp.49-57
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• 2003

The flight trajectory of a boomerang is predicted with the momentum theory (actuating disk theory) and the blade element method generally used as tools to analyze in the rotary-wing aerodynamics. Boomerangs made by students are actually compared with the computational results, utilized to get the physical intuition. The transition from helicopter mode to autogyro mode with the gyroscopic precession is observed in numerical analysis and experiment like a 'flying rotor' after the boomerang taking off. The whole system is shown to be highly nonlinear and very sensitive to the initial conditions. Various flight loci may be obtained if we change the parameters.

• Wind and Structures
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• v.34 no.1
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• pp.151-159
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• 2022

The aerodynamics of blunt bodies with separation at the sharp corner of the leading edge and reattachment on the body side are particularly important in civil engineering applications. In recent years, a number of experimental and numerical studies have become available on the aerodynamics of a rectangular cylinder with chord-to-thickness ratio equal to 5 (BARC). Despite the interest in the topic, a widely accepted set of guidelines for grid generation about these blunt bodies is still missing. In this work a new, well resolved Direct Numerical Simulation (DNS) around the BARC body at Re=3000 is presented and its results compared to previous DNSs of the same case but with different numerical approaches and mesh. Despite the simulations use different numerical approaches, mesh and domain dimensions, the main discrepancies are ascribed to the different grid spacings employed. While a more rigorous analysis is envisaged, where the order of accuracy of the schemes are kept the same while grid spacings are varied alternately along each spatial direction, this represents a first attempt in the study of the influence of spatial resolution in the Direct Numerical Simulation of flows around elongated rectangular cylinders with sharp corners.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.791-794
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• 2002

Cavity is inevitably included in automobile vehicle configuration. The complex unsteady flow and sound waves generated by the cavity are very important issues because of the involved fluid dynamics and the practical importance in the field of aerodynamics. The LES method used is a conventional one with Smagorinsky eddy-viscosity model and the computational grid is small enough to be handled by workstation-level computers. LES can successfully simulate of cavity noise analysis.

• Advances in aircraft and spacecraft science
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• v.2 no.2
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• pp.199-215
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• 2015

This study focuses on the limit cycle oscillations (LCOs) of cantilever swept-back wings containing a cubic nonlinearity in an incompressible flow. The governing aeroelastic equations of two degrees-of-freedom swept wings are derived through applying the strip theory and unsteady aerodynamics. In order to apply strip theory, mode shapes of the cantilever beam are used. The harmonic balance method is used to calculate the frequencies of LCOs. Linear flutter analysis is conducted for several values of sweep angles to obtain the flutter boundaries.

• Korean Journal of Computational Design and Engineering
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• v.5 no.2
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• pp.184-195
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• 2000

MDO (Multidisciplinary Design Optimization) methodology is an emerging new technology to solve a complicate structural analysis and design problem with a large number of design variables and constraints. In this paper MDO methodology is adopted through the use of computer aided systems such as Geometric Solid Modeller, Mesh Generator, CAD system and CAE system. And this paper introduces MDO methodology as a new method for structural analysis and design through the application to the structural design of flap drive system. In a MDO methodology application to the structural design of flap drive system, kinetodynamic analysis is done using a simple aerodynamic analysis model for the air flow over the flap surface instead of difficult aerodynamic analysis. Simultaneously the structural static analysis is done to obtain the optimum structural condition. And the structural buckling analysis for push pull rod is also done to confirm the optimum structural condition (optimum cross section shape of push pull rod).

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.191-191
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• 2010

As many researchers want to predict or assess more about wind condition and wind power generation, CFD(Computational Fluid Dynamics) analysis method is very good way to do predict or assess wind condition and power generation. But CFD analysis is needed much knowledge of aerodynamics and physical fluid theory. In this paper, Auto-Wind CFD analysis program will be introduced. User does not need specific knowledge of CFD or fluid theory. This program just needs topographical data and wind data for initial condition. Then all of process is running automatically without any order of user. And this program gives for user to select and set initial condition for advanced solving CFD. At the last procedure of solving, Auto-Wind program shows analysis of topography and wind condition of target area. Moreover, Auto-Wind can predict wind power generation with calculation in the program. This Auto-Wind analysis program will be good tool for many wind power researchers in real field.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.2
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• pp.162-171
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• 2013

A general purpose aircraft mission performance analysis program has been developed. The program can be used in design mode or in analysis mode. Fuel weight for a given mission profile can be estimated when the design mode is chosen, while mission time or mission range for a given fuel can be estimated when the analysis mode is chosen. The mission analysis program is written with JAVA and includes GUI(Graphic User Interface) for users' conveniences. With a proper combination of databases for propulsion, aerodynamics and weight, the program can be configured to compute the performance of any type of aircraft. The program is validated by comparing its results with the results of a well known performance analysis program by ADD(Agency for Defense Development).

• Journal of the Korean Society for Railway
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• v.9 no.5 s.36
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• pp.511-516
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• 2006

A standard framework of CFD(Computational Fluid dynamics) analysis for railway system has been developed to evaluate the overall aerodynamic performance of railway system and has been adopted to numerical simulation of the pressure field around KTX train. The framework is composed of standard aerodynamic model and standard aerodynamic performance to customize the general CFD solution process reflecting the characteristics of railway system such as various operation mode and performance factors. The results show that the standard framework of CFD analysis for railway system can provide objectivity and consistency to the CFD analysis for railway system and the pressure field around KTX train has been successively solved.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.1
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• pp.110-122
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• 2015

In this paper, the unsteady aerodynamics and blade structural dynamics of an experimental bearingless rotor were analyzed. Due to the multiple load path and nonlinear behavior of a bearingless rotor, sophisticated structural modeling and structural-aerodynamic coupled analysis is required. To predict the internal load and deformation of an experimental bearingless rotor, trim analysis was implemented. The results showed good agreement when compared with those predicted by CAMRAD II the rotorcraft comprehensive analysis. It is possible to extend the present structural-aerodynamic combined analysis to further advanced configurations of the bearingless rotor in the future.