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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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International Journal of Aeronautical and Space Sciences
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Journal DOI :
The Korean Society for Aeronautical & Space Sciences
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Volume & Issues
Volume 14, Issue 4 - Dec 2013
Volume 14, Issue 3 - Sep 2013
Volume 14, Issue 2 - Jun 2013
Volume 14, Issue 1 - Mar 2013
Selecting the target year
Radiation Phenomena in Planetary Entries
Park, Chul ;
International Journal of Aeronautical and Space Sciences, volume 14, issue 2, 2013, Pages 105~111
DOI : 10.5139/IJASS.2013.14.2.105
Radiative heating phenomena occurring in planetary entry flights are reviewed for the purpose of educating those who are not familiar with the problem. How the radiative heat transfer rates to the Apollo entry vehicle were measured and analyzed are first described. Next, the effects of thermo-chemical non-equilibrium on radiation are summarized. Then the radiation problems in entry flights into other planets are reviewed. Finally, unsolved problems are enumerated.
Optimization of LU-SGS Code for the Acceleration on the Modern Microprocessors
Jang, Keun-Jin ; Kim, Jong-Kwan ; Cho, Deok-Rae ; Choi, Jeong-Yeol ;
International Journal of Aeronautical and Space Sciences, volume 14, issue 2, 2013, Pages 112~121
DOI : 10.5139/IJASS.2013.14.2.112
An approach for composing a performance optimized computational code is suggested for the latest microprocessors. The concept of the code optimization, termed localization, is maximizing the utilization of the second level cache that is common to all the latest computer systems, and minimizing the access to system main memory. In this study, the localized optimization of the LU-SGS (Lower-Upper Symmetric Gauss-Seidel) code for the solution of fluid dynamic equations was carried out in three different levels and tested for several different microprocessor architectures widely used these days. The test results of localized optimization showed a remarkable performance gain of more than two times faster solution than the baseline algorithm for producing exactly the same solution on the same computer system.
Grid Discretization Study for the Efficient Aerodynamic Analysis of the Very Light Aircraft (VLA) Configuration
Sitio, Moses ; Kim, Sangho ; Lee, Jaewoo ;
International Journal of Aeronautical and Space Sciences, volume 14, issue 2, 2013, Pages 122~132
DOI : 10.5139/IJASS.2013.14.2.122
In this research the development of unstructured grid discretization solution techniques is presented. The purpose is to describe such a conservative discretization scheme applied for experimental validation work. The objective of this paper is to better establish the effects of mesh generation techniques on velocity fields and particle deposition patterns to determine the optimal aerodynamic characteristics. In order to achieve the objective, the mesh surface discretization approaches used the VLA prototype manufacturing tolerance zone of the outer surface. There were 3 schemes for this discretization study implementation. They are solver validation, grid convergence study and surface tolerance study. A solver validation work was implemented for the simple 2D and 3D model to get the optimum solver for the VLA model. A grid convergence study was also conducted with a different growth factor and cell spacing, the amount of mesh can be controlled. With several amount of mesh we can get the converged amount of mesh compared to experimental data. The density around surface model can be calculated by controlling the number of element in every important and sensitive surface area of the model. The solver validation work result provided the optimum solver to employ in the VLA model analysis calculation. The convergence study approach result indicated that the aerodynamic trend characteristic was captured smooth enough compared with the experimental data. During the surface tolerance scheme, it could catch the aerodynamics data of the experiment data. The discretization studies made the validation work more efficient way to achieve the purpose of this paper.
Flutter Characteristics of a Morphing Flight Vehicle with Varying Inboard and Outboard Folding Angles
Shrestha, Pratik ; Jeong, Min-Soo ; Lee, In ; Bae, Jae-Sung ; Koo, Kyo-Nam ;
International Journal of Aeronautical and Space Sciences, volume 14, issue 2, 2013, Pages 133~139
DOI : 10.5139/IJASS.2013.14.2.133
Morphing aircraft capable of varying their wing form can operate efficiently at various flight conditions. However, radical morphing of the aircraft leads to increased structural complexities, resulting in occurrence of dynamic instabilities such as flutter, which can lead to catastrophic events. Therefore, it is of utmost importance to investigate and understand the changes in flutter characteristics of morphing wings, to ensure uncompromised safety and maximum reliability. In this paper, a study on the flutter characteristics of the folding wing type morphing concept is conducted, to examine the effect of changes in folding angles on the flutter speed and flutter frequency. The subsonic aerodynamic theory Doublet Lattice Method (DLM) and p-k method are used, to perform the flutter analysis in MSC.NASTRAN. The present baseline flutter characteristics correspond well with the results from previous study. Furthermore, enhancement of the flutter characteristics of an aluminum folding wing is proposed, by varying the outboard wing folding angle independently of the inboard wing folding angle. It is clearly found that the flutter characteristics are strongly influenced by changes in the inboard/outboard folding angles, and significant improvement in the flutter characteristics of a folding wing can be achieved, by varying its outboard wing folding angle.
High Velocity Impact Characteristics of Shear Thickening Fluid Impregnated Kevlar Fabric
Park, Yurim ; Baluch, Abrar H. ; Kim, YunHo ; Kim, Chun-Gon ;
International Journal of Aeronautical and Space Sciences, volume 14, issue 2, 2013, Pages 140~145
DOI : 10.5139/IJASS.2013.14.2.140
The development of high performance fabrics have advanced body armor technology and improved ballistic performance while maintaining flexibility. Utilization of the shear thickening phenomenon exhibited by Shear Thickening Fluids (STF) has allowed further enhancement without hindering flexibility of the fabric through a process of impregnation. The effect of STF impregnation on the ballistic performance of fabrics has been studied for impact velocities below 700 m/s. Studies of STF-impregnated fabrics for high velocity impacts, which would provide a transition to significantly higher velocity ranges, are lacking. This study aims to investigate the effect of STF impregnation on the high velocity impact characteristics of Kevlar fabric by effectively dispersing silica nanoparticles in a suspension, impregnating Kevlar fabrics, and performing high velocity impact experiments with projectile velocities in the range of 1 km/s to compare the post impact characteristics between neat Kevlar and impregnated Kevlar fabrics. 100 nm diameter silica nanoparticles were dispersed using a homogenizer and sonicator in a solution of polyethylene glycol (PEG) and diluted with methanol for effective impregnation to Kevlar fabric, and the methanol was evaporated in a heat oven. High velocity impact of STF-impregnated Kevlar fabric revealed differences in the post impact rear formation compared to neat Kevlar.
Patch-type large strain sensor using elastomeric composite filled with carbon nanofibers
Yasuoka, Tetsuo ; Shimamura, Yoshinobu ; Todoroki, Akira ;
International Journal of Aeronautical and Space Sciences, volume 14, issue 2, 2013, Pages 146~151
DOI : 10.5139/IJASS.2013.14.2.146
Carbon nanofibers (CNFs) are electrically conductive. When CNFs are used as fillers in resin, this electrical conductivity can be yielded without adversely affecting the mechanical properties of the resin. When an elastomer is adopted as the resin, a conductive elastomer can then be produced. Due to its flexibility and conductive properties, a large strain sensor based on changes in resistivity may be produced, for strain sensing in flexible structures. In this study, a patch-type large strain sensor using resistivity change in a CNF/elastomer composite was proposed. The measurement limits of the sensor were investigated experimentally, and the limit was found to be 40%, which greatly exceeded the limits of conventional metal-foiled strain gages. Also, the proposed CNF/elastomer large strain sensor can be used to measure flexible materials, while conventional strain gages cannot be used to measure such strains.
Control Effectiveness Analysis of the hawkmoth Manduca sexta: a Multibody Dynamics Approach
Kim, Joong-Kwan ; Han, Jae-Hung ;
International Journal of Aeronautical and Space Sciences, volume 14, issue 2, 2013, Pages 152~161
DOI : 10.5139/IJASS.2013.14.2.152
This paper presents a control effectiveness analysis of the hawkmoth Manduca sexta. A multibody dynamic model of the insect that considers the time-varying inertia of two flapping wings is established, based on measurement data from the real hawkmoth. A six-degree-of-freedom (6-DOF) multibody flight dynamics simulation environment is used to analyze the effectiveness of the control variables defined in a wing kinematics function. The aerodynamics from complex wing flapping motions is estimated by a blade element approach, including translational and rotational force coefficients derived from relevant experimental studies. Control characteristics of flight dynamics with respect to the changes of three angular degrees of freedom (stroke positional, feathering, and deviation angle) of the wing kinematics are investigated. Results show that the symmetric (asymmetric) wing kinematics change of each wing only affects the longitudinal (lateral) flight forces and moments, which implies that the longitudinal and lateral flight controls are decoupled. However, there are coupling effects within each plane of motion. In the longitudinal plane, pitch and forward/backward motion controls are coupled; in the lateral plane, roll and side-translation motion controls are coupled.
Development of Aircraft Mission Performance Analysis Program
Lee, Hyunseok ; Lee, Hyungjoon ; Kwak, Einkeun ; Lee, Seungsoo ; Bae, Seungho ;
International Journal of Aeronautical and Space Sciences, volume 14, issue 2, 2013, Pages 162~171
DOI : 10.5139/IJASS.2013.14.2.162
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).
Modeling and designing intelligent adaptive sliding mode controller for an Eight-Rotor MAV
Chen, Xiang-Jian ; Li, Di ;
International Journal of Aeronautical and Space Sciences, volume 14, issue 2, 2013, Pages 172~182
DOI : 10.5139/IJASS.2013.14.2.172
This paper focuses on the modeling and intelligent control of the new Eight-Rotor MAV, which is used to solve the problem of the low coefficient proportion between lift and gravity for the Quadrotor MAV. The Eight-Rotor MAV is a nonlinear plant, so that it is difficult to obtain stable control, due to uncertainties. The purpose of this paper is to propose a robust, stable attitude control strategy for the Eight-Rotor MAV, to accommodate system uncertainties, variations, and external disturbances. First, an interval type-II fuzzy neural network is employed to approximate the nonlinearity function and uncertainty functions in the dynamic model of the Eight-Rotor MAV. Then, the parameters of the interval type-II fuzzy neural network and gain of sliding mode control can be tuned on-line by adaptive laws based on the Lyapunov synthesis approach, and the Lyapunov stability theorem has been used to testify the asymptotic stability of the closed-loop system. The validity of the proposed control method has been verified in the Eight-Rotor MAV through real-time experiments. The experimental results show that the performance of the interval type-II fuzzy neural network based adaptive sliding mode controller could guarantee the Eight-Rotor MAV control system good performances under uncertainties, variations, and external disturbances. This controller is significantly improved, compared with the conventional adaptive sliding mode controller, and the type-I fuzzy neural network based sliding mode controller.
Spacecraft Formation Reconfiguration using Impulsive Control Input
Bae, Jonghee ; Kim, Youdan ;
International Journal of Aeronautical and Space Sciences, volume 14, issue 2, 2013, Pages 183~192
DOI : 10.5139/IJASS.2013.14.2.183
This paper presents formation reconfiguration using impulsive control input for spacecraft formation flying. Spacecraft in a formation should change the formation size and/or geometry according to the mission requirements and space environment. To modify the formation radius and geometry with respect to the leader spacecraft, the follower spacecraft generates additional control inputs; the two impulsive control inputs are general control type of the spacecraft system. For the impulsive control input, Lambert`s problem is modified to construct the transfer orbit in relative motion, given two position vectors at the initial and final time. Moreover, the numerical simulation results show the transfer trajectories to resize the formation radius in the radial/along-track plane formation and in the along-track/cross-track plane formation. In addition, the maneuver characteristics are described by comparing the differential orbital elements between the reference orbit and transfer orbit in the radial/along-track plane formation and along-track/cross-track plane formation.
Earth Albedo perturbations on Low Earth Orbit Cubesats
Khalifa, N.S. ; Sharaf-Eldin, T.E. ;
International Journal of Aeronautical and Space Sciences, volume 14, issue 2, 2013, Pages 193~199
DOI : 10.5139/IJASS.2013.14.2.193
This work investigates the orbital perturbations of the cubesats that lie on LEO due to Earth albedo. The motivation for this paper originated in the investigation of the orbital perturbations for closed- Earth pico-satellites due to the sunlight reflected by the Earth (the albedo). Having assumed that the Sun lies on the equator, the albedo irradiance is calculated using a numerical model in which irradiance depends on the geographical latitude, longitude and altitude of the satellite. However, in the present work the longitude dependency is disregarded. Albedo force and acceleration components are formulated using a detailed model in a geocentric equatorial system in which the Earth is an oblate spheroid. Lagrange planetary equations in its Gaussian form are used to analyze the orbital changes when
. Based on the Earth`s reflectivity data measured by NASA Total Ozone Mapping Spectrometer (TOMS project), the orbital perturbations are calculated for some cubesats. The outcome of the numerical test shows that the albedo force has a significant contribution on the orbital perturbations of the pico-satellite which can affect the satellite life time.