• International Journal of Aeronautical and Space Sciences
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• 제8권1호
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• pp.1-9
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• 2007

As a first step toward a complete CFD-CSD coupling for helicopter rotor load analysis, the present study attempts to loosely couple a CFD code with a source-double panel method. The far-field wake effects were calculated by a time-marching free vortex wake method and were implemented into the CFD module via field velocity approach. Unlike the lifting line method, the air loads correction process is not trivial for the source-doublet panel method. The air loads correction process between the source-doublet method and CFD is newly suggested in this work and the computation results are validated against available data for well-known hovering flight conditions.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.264-271
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• 2007

The flow simulations around ducted-prop of tilt-duct aircraft were conducted in this study. For the investigation of aerodynamic characteristics of various configurations of duct, the axisymmetric flow calculation method combined with actuator disk model for prop were used. The rapid two-dimensional calculation and fast grid generation enable aerodynamic analysis for various duct configurations in a very short time and anticipated to active role in optimal configuration design of duct exposed to various flight modes. For the case of angle of attack or tilt angle, the three dimensional flow calculation is conducted using the three dimensional grid simply generated by just revolving the axisymmetric grid around center axis. Through the three dimensional calculation around duct, the aerodynamic effectiveness of duct as a lifting surface in airplane mode was investigated. The flow calculations around the control vane (wing) installed in the rear section of duct were conducted The aerodynamic data of wing were compared with the data of the ducts to evaluate the aerodynamic effectiveness of ducts.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 추계 학술대회논문집
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• pp.131-135
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• 2006

The aerodynamic characteristics of a T-50 aircraft configuration are investigated by a subsonic panel method. Panel methods are best applicable to the lifting surfaces such as wings and airfoils. Source and doublets are used in the present code as a basic singularities of the panel technique. The panel method is first assessed by applying it to several benchmark problems for which other solutions and experimental data are available, such as a swept wing and wing body configuration. The prediction results are compared with experimental data and show good agreement in all cases considered. Finally, the method is applied to a T-50 aircraft configuration and excellent agreement with flight test data in lift coefficients is found.

• The Journal of the Acoustical Society of Korea
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• 제16권1E호
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• pp.29-34
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• 1997

Numerical prediction of aerodynamic noise radiated by subsonic rotors are carried out. A computer program has been developed which incorporates both the discrete frequency noise as well as the broadband noise arising from the ingestion of turbulence. Acoustic analogy is used in conjunction with Homicz's formulation of turbulence ingestion noise. Formulation 1A of Farassat is used to enhance the numerical analysis performance of Ffowcs-Williams Hawkings equation by eliminating the numericla time differentiation. Homicz's trubulence ingestion noise prediction technique is used to understand the characteristics of broadband noise radiated by isotropic trubulence in gestion. Numerical predictions are carried out for a number of rotor configurations and compared with experimental data. Monopole consideration of transonic rotor agrees well with both the experimental data and the linear theory. Noise radiation characteristics of rotor at lifting hover are investigated utilizing simple blade loading obtained by thin wing section theory. By incorporating discrete noise prediction of steady loading with broadband spectrum, much better agreement with experimental data is obtained in the low frequency region. The contributions from different noise mechanisms can also be analyzed through this method.

• 항공우주시스템공학회지
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• 제10권1호
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• pp.1-7
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• 2016

During flight of the aircraft, the vortex merging phenomenon appears under the certain condition between co-rotating vortices which were generated at the wing tip and lifting-surface. And then these merged vortices at both sides show counter-rotating pattern to affect on the downstream of the aircraft. In this paper, the numerical simulations are conducted assuming this phenomenon in two-dimensional co-rotating or counter-rotating vortices pairs. Two-dimensional incompressible Navier-Stokes equations were converted into Vorticity-Streamfunction form and the Galerkin spectral method was adopted. The third order Runge-Kutta method was used for time integration. The effects on the vortex merger and degree of vortex merger were investigated according to time, Reynolds number, and changes in the distance between two vortices.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.876-881
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• 2003

This study focused on to design and toanalysis of a myoelectronic hand. We considered a low frequency factor in human life and to quantify low frequency which a human body responded to using a 1-axis ant a 3-axis accelerometer. The dynamic myoelectronic hand are important for tasks such a continuous prosthetic control and a EMG signal recognition, which have not been successfully mastered by the most neural approached To control myoelectronic hand, classifying myoelectronic patterns are also important. Experimental results of FEM are 110㎫ on Thumb, 200㎫ on Index finger, 220㎫ on Middle finger 260㎫ on Ring finger and 270㎫ on Little finger. Experimental results of accelerometer are 1.4-0.4(m/s2) ,(5-20(〔Hz〕) in Feeding activity and 0.4-0(m/s2) (0-10〔Hz〕) in Lifting activity. Considering these facts, we suggest a new type myoelectronic hand.

• 대한조선학회논문집
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• 제41권2호
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• pp.12-20
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• 2004

In this study, a linearized super-cavitation theory was applied in order to analyse the performance of the 2-dimensional foils. For flat plate with non-thickness, the numerical results correlated very well with Nishiyama's theoretical results for closed cavitation model. For plano-convex section, the numerical results correlated very well with Wade's experimental data. The new lifting surface procedure, developed and validated in this study, is generally considered applicable to the performance analyses of the super-cavitating propeller and trans-cavitating propeller.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1997년도 추계학술대회논문집
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• pp.168-176
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• 1997

The purpose of this study is to know load for each human body's knee joint to endure load efficiently, when weight lifter pulls suitable bar in the each weight lifting level. To use the difference of load and correlation between men and women, the conclusion of this stduy is to find parameters to conduct maximum limitation of maximum load to search maximum limitation. The moment of each joint in the lower area was to have a much difference between group of the turunk in the first step. It decreased rapidly until decent and greatly pulled in the second step. Neuromusclar moment increased suddenly in the decrease phase. This phenomenon resulted from shock-absorbing function to sbsorb a load from bar.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 추계 학술대회논문집
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• pp.106-113
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• 2003

Smart UAV Development Program, one of the 21c Frontier R&D Program sponsored by MOST(Ministry of Science and Technology), was launched in 2002. As an air vehicle for the Smart UAV, CRW(Canard Rotor/Wing) concept was one of the candidates compared in trade-off study. The CRW concept has not only been proven completely but its aerodynamic characteristics not known in detail yet. Two calculation methods were adopted in this study to obtain aerodynamic data for the CRW. First method was the superpose DATCOM method which is capable of three lifting surfaces, and second one is the full Navier-Stokes computation around CRW configuration using overset grid method. Basic aerodynamic characteristics of the CRW configuration was analyzed and the minimum drag level with lift to drag ratio is presented. The peculiar flow characteristics around rotor/wing and hub were also examined and considered in the configuration design.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권2호
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• pp.177-184
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• 2017

The Coanda effect is the phenomenon of a fluid jet to stay attached to a curved surface; when a jet stream is applied tangentially to a convex surface, lift force is generated by increase in the circulation. The Coanda effect has great potential to be applied practically applied to marine hydrodynamics where various lifting surfaces are being widely used to control the behavior of ships and offshore structures. In the present study, Numerical simulations and corresponding experiments were performed to ascertain the applicability of the Coanda effect to a horn-type rudder. It was found that the Coanda jet increases the lift coefficient of the rudder by as much as 52% at a jet momentum coefficient of 0.1 and rudder angle of $10^{\circ}$.