• 한국전산유체공학회:학술대회논문집
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• 2007.04a
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• pp.116-119
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• 2007

In this study the unsteady aerodynamic analysis of a hovering helicopter rotor is performed. For the accurate flow field analysis Euler equations and the free wake method are coupled. The Euler equations are solved to find the pressure distribution around the rotor, and free wake method is used to give the boundary condition for the solution of Euler equations. Also, vortex strength and wake motion after the rotor are simulated by the free wake method. The accuracy of the present method is compared with the source sink model. The present method is applied to the hovering Caradonna-Tung rotor and compared with experimental results.

• Journal of Aerospace System Engineering
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• v.6 no.2
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• pp.23-27
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• 2012

The evaluation of simulation models against ADS-33 quantitative rotorcraft handling qualities metrics has, in the past, been a time consuming effort, involving many individual analyses in both the time and frequency domains. Manual tuning of control system parameters to meet handling qualities and performance specifications has been cumbersome and complicated. Performing rigorous trade-off studies for numerous variations in the control system is too time consuming to be practicable. With the complex interaction of time- and frequency based specifications for the closed- and broken-loop responses, it is difficult to know if the design makes the most effective use of the available control power. The Control Designer's Unified Interface (CONDUIT) software makes possible rapid optimization and trade-offs of design configurations against handling qualities specifications.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.1
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• pp.44-50
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• 2008

In this study a turboshaft engine for a helicopter propulsion system was modeled using SIMULINK and the components' maps were generated from the limited performance deck data provided by engine supplier using a hybrid method with the genetic algorithms and the system identification method. In order to verify the SIMULINK performance model and the component maps generated by the hybrid method, the steady-state performance analysis results were compared with the performance data provided by engine manufacturer. In this investigation, it was confirmed that the analysis results by the proposed model are closely met with those by engine manufacturer's data.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.9
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• pp.796-805
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• 2016

As a part of the first stage in the helicopter flight simulator development, this study numerically evaluates handling qualities of the dynamics model. The flight dynamics model was generated using public information for AS365 N2, the target aircraft of the simulator. The flight simulator is under development as a pilot training and research tool for firefighting missions. The assessment of the model intends to validate general characteristics and suitability before the model is enhanced with flight test data. The evaluation is based on the ADS-33E-PRF(Aeroautical Design Standard Performance Specification Handling Qualities Requirement) criteria, with consideration of category of the aircraft, missions, and environment. The numerical operations follow required or recommended procedures of flight test for compliance demonstration. Evaluation results are evaluated according to the rating specified in maneuverability ADS-33E-PRF. Results have identified to provide a satisfactory platform for flight dynamic model in the general helicopter simulator generated based on the RotorLibFDM, and can be used as a base for basic training and research.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.2
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• pp.111-116
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• 2008

The study installed non metric camera which was a 10 Mega Pixel camera in RC Helicopter. And the study controlled images hotographed in air on land, considering their overlap. The study could express DEM by abstracting TIN from the acquired images through image registration. Also, the study compared and examined accuracy between reference point and check point observed by Total Station which was a conventional type of survey. As the results, the study could get errors of $-0.194{\sim}0.224\;m$ on X axis, $-0.088{\sim}0.180\;m$ on Y axis and $-0.286{\sim}0.285\;m$ on Z axis. Expressing an error's RMSE in the checkpoint, the study could get of 0.021388 m on X axis, 0.015285 m on Y axis and 0.041872 m on Z axis. It is judged that the above photographing and analyzing technique are better than the existing Total Station to acquire more terrain elevation data.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.6
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• pp.495-501
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• 2013

Korean Utility Helicopter (KUH) has been designed to avoid the blade passing frequency and any instability due to a coupling of dynamic characteristics between the main rotor and the airframe in ground operation. For these design objectives, the vibration analysis and the ground resonance analysis were performed to analyze the dynamic characteristics of the airframe and the main rotor. Then, the whirl-tower test was conducted to identify the dynamic characteristics of the main rotor and the ground vibration test (GVT) was conducted to identify the dynamic characteristics of the airframe. The GVT for KUH was conducted with the test conditions and test articles established in consideration of each flight and ground condition. This paper shows the method and technique for performing the GVT for KUH and presents the correlation technique and the results for the correlated analysis model.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.8
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• pp.731-738
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• 2015

The rapid prototyping process and development tool which enable the control law evaluation efficiently are needed to minimize the development cycle, cost and risk of aircraft flight control system. This paper describes a development process that integrates the designed control law into HETLAS to evaluate simulation effectively using nonlinear mathematical models. The desktop engineering simulator was developed using HETLAS for the piloted simulation evaluation of a various control modes and the procedure was developed, which quickly integrates the HETLAS into HQS(Handling Quality Simulator) and HILS(Hardware In the Loop Simulation) environments. This paper presents a rapid prototyping process using HETLAS that significantly shortens the integration process of the control law into the nonlinear math model, HETLAS, and allows the control law designs to be quickly tested in the piloted simulation and HILS environments.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.2
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• pp.139-146
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• 2009

In this study, an assessment is made for the helicopter vibration reduction of composite rotor blades using an active twist control concept. The piezoceramic shear actuation mechanism along with elastic couplings of composite blades is used for vibration reduction. The rotor blades are modeled as composite box-beams with actuator layers bonded on the outer surfaces of the thin-walled section. The governing equations of motion for helicopter blades are obtained using Hamilton's principle. A time domain unsteady aerodynamic theory with free wake model is used to obtain the airloads. Various rotor configurations with different elastic couplings with appropriate actuator placement are used to investigate the hub vibration characteristics. Numerical results show that a substantial reduction of $N_b$/rev hub vibration can be achieved using the optimal control algorithm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.2
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• pp.103-110
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• 2022

Degradation of handling qualities(HQs) due to bad weather or mechanical failure can pose a fatal risk to pilots unfamiliar with such situation. In particular, icing is an important issue to consider as it is a frequent cause of accidents. Most of the previous research works focuses on aerodynamic performance changes due to icing and the corresponding icing modeling or methods to prevent icing, whereas the present work attempts to actively compensate for HQ degradation due to icing on a full-scale helicopter through flight control law design. To this end, the present work first demonstrates HQ degradation due to icing using CONDUIT software, and subsequently presents a robust control design via the RS-LQR(Robust Servomechanism Linear Quadratic Regulation) procedure to compensate for the HQ degradation. Simulation results show that the proposed robust control maintains Level 1 HQ in the presence of icing.

• Composites Research
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• v.35 no.5
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• pp.340-346
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• 2022

In this study, an optimal structural design of composite helicopter blades is performed using the genetic algorithm-based optimizer PSGA (Particle Swarm assisted Genetic Algorithm). The blade sections consist of the skin, spar, form, and balancing weight. The sectional geometries are generated using the B-spline curves while an opensource code Gmsh is used to discretize each material domain which is then analyzed by a finite element sectional analysis program Ksec2d. The HART II blade formed based on either C- or D-spar configuration is exploited to verify the cross-sectional design framework. A numerical simulation shows that each spar model reduces the blade mass by 7.39% and 6.65%, respectively, as compared with the baseline HART II blade case, while the shear center locations being remain close (within 5% chord) to the quarter chord line for both cases. The effectiveness of the present optimal structural design framework is demonstrated, which can readily be applied for the structural design of composite helicopter blades.