Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
International Journal of Aeronautical and Space Sciences
Journal Basic Information
Journal DOI :
The Korean Society for Aeronautical & Space Sciences
Editor in Chief :
Volume & Issues
Volume 3, Issue 2 - Nov 2002
Volume 3, Issue 1 - May 2002
Selecting the target year
Numerical Analysis on the Discharge Characteristics of a Liquid Rocket Engine Injector Orifice
Cho, Won-Kook ; Kim, Young-Mog ;
International Journal of Aeronautical and Space Sciences, volume 3, issue 1, 2002, Pages 1~8
DOI : 10.5139/IJASS.2002.3.1.001
A numerical analysis was performed on the fluid flow in injector orifice of a liquid rocket engine. The present computational code was verified against the published data for turbulent flow in a pipe with a sudden expansion-contraction. Considered were the parameters for the flow analysis in an injector orifice: Reynolds number, ratio of mass flow rate of the injector orifice and inlet flow rate, and slant angle of the injector orifice. The discharge coefficient increased slightly as the Reynolds number increased. The slant angle of the injector changed critically the discharge coefficient. The discharge coefficient increased by 7% when the slant angle changed from
The ratio of mass flow rate had relatively little impact on the discharge coefficient.
Theoretical and Experimental Considerations of Thermal Humidity Characteristics
Choi, Seok-Weon ; Cho, Ju-Hyeong ; Seo, Hee-Jun ; Lee, Sang-Seol ;
International Journal of Aeronautical and Space Sciences, volume 3, issue 1, 2002, Pages 9~18
DOI : 10.5139/IJASS.2002.3.1.009
Thermal humidity characteristics were considered theoretically and experimentally. A Simply well-fitted correlation of a saturated vapor pressure-temperature curve of water was introduced based on Antoine equation to make theoretical prediction of relative humidity according to temperature variation. Characteristics of dew point were also examined theoretically and its relation with temperature and humidity was evaluated. The exact mass of water vapor in a specified humidity and temperature condition was estimated to provide useful insight into the idea about how much amount of water corresponds to a specified humidity and temperature condition in a confined system. A simple but well-fitting model of dehumidification process was introduced to anticipate the trend of relative humidity level during GN2(gaseous nitrogen) purge process in a humidity chamber. Well-suitedness of this model was also verified by comparison with experimental data. The overall appearance and specification of two thermal humidity chambers were introduced which were used to perform various thermal humidity tests in order to yield useful data necessary to support validity of theoretical models.
Decentralized Filters for the Formation Flight
Song, Eun-Jung ;
International Journal of Aeronautical and Space Sciences, volume 3, issue 1, 2002, Pages 19~29
DOI : 10.5139/IJASS.2002.3.1.019
Decentralized filtering for a formation flight instrumentation system by INS/GPS integration is considered in this paper. An elaborate tuning method of the measurement noise covariance is suggested to compensate modeling errors caused by decentralizing the extended Kalman filter. It does not require large data transfer between formation vehicles. Covariance analysis exhibits the superior performance of the proposed approach when compared with the existent decentralized filter and the global filter, which has the target-filter performance.
Solutions of Radiative Transfer for Nongray Gases within a 3-D Cylindrical Enclosure
Park, Won-Hee ; Jung, Hyun-Sung ; Kim, Tae-Kuk ;
International Journal of Aeronautical and Space Sciences, volume 3, issue 1, 2002, Pages 30~38
DOI : 10.5139/IJASS.2002.3.1.030
In multi-dimensional systems, various solution schemes for radiative transfer are suggested but the applicabilities and accuracies of these schemes have not yet fully tested due to the lack of reference solutions especially for nongray gases. In this paper we present some precise radiative transfer solutions for a black walled 3-dimensional cylindrical system filled with nongray gases having uniform temperature and concentration. The ray-tracing method with the
quadrature set and the SNB model are used to obtain the radiative transfer solutions by the nongray gases. The solutions presented in this paper are proved to be quite accurate and can be regarded as the reference solutions for the radiative transfer by nongray gases.
Robust Tracker Design Method Based on Multi-Trajectories of Aircraft
Kim, Eung-Tai ; Andrisani, D. II ;
International Journal of Aeronautical and Space Sciences, volume 3, issue 1, 2002, Pages 39~49
DOI : 10.5139/IJASS.2002.3.1.039
This paper presents a robust tracker design method that is specific to the trajectories of target aircraft. This method assumes that representative trajectories of the target aircraft are available. The exact trajectories known to the tracker enables the incorporation of the exact data in the tracker design instead of the measurement data. An estimator is designed to have acceptable performance in tracking a finite number of different target trajectories with a capability to trade off the mean and maximum errors between the exact trajectories and the estimated or predicted trajectories. Constant estimator gains that minimize the cost functions related to the estimation or prediction error are computed off-line from an iterative algorithm. This tracker design method is applied to the longitudinal motion tracking of target aircraft.
Accelerated Co-evolutionary Algorithms
Kim, Jong-Han ; Tahk, Min-Jea ;
International Journal of Aeronautical and Space Sciences, volume 3, issue 1, 2002, Pages 50~60
DOI : 10.5139/IJASS.2002.3.1.050
A new co-evolutionary algorithm, of which the convergence speed is accelerated by neural networks, is proposed and verified in this paper. To reduce computational load required for co-evolutionary optimization processes, the cost function and constraint information is stored in the neural networks, and the extra offspring group, whose cost is computed by the neural networks, is generated. It increases the offspring population size without overloading computational effort; therefore, the convergence speed is accelerated. The proposed algorithm is applied to attitude control design of flexible satellites, and it is verified by computer simulations and experiments using a torque-free air bearing system.
A Conceptual Design of HAUSAT-1(CubeSat) Satellite
Kim, Joon-Tae ; Kim, Young-Suk ; Seo, Seung-Won ; Kim, Young-Hyun ; Chang, Young-Keun ;
International Journal of Aeronautical and Space Sciences, volume 3, issue 1, 2002, Pages 61~73
DOI : 10.5139/IJASS.2002.3.1.061
This paper addresses the conceptual design results of the HAUSAT-1 (Hankuk Aviation University SATellite-1), developed by Space System Research Lab. of Hankuk Aviation Univ., which is a new generation picosatellite. This project has been funded by Korean Government for the purpose of developing the space core technology. This is the first attempt at the level of university in Korea to develop the satellite weighing less than 1kg and accelerates opportunities with low construction, low launch cost space experiment platforms. The purpose of the HAUSAT-1 project is to offer graduate and undergraduate students great opportunities to be able to understand the design process of satellite development as a team member. Its mission objectives are to track its position by the GPS receiver system, to deploy the thin film solar cell panel to generate extra power, and to measure plasma density and temperature with the plasma sensor. The HAUSAT-1 will orbit at the altitude of 650 km with 65 degree inclination angle with 12 months of design mission life. It is planned to be launched on November 2003 by Russian launch vehicle "Dnepr".
Numerical Simulation of Shock Wave Reflecting Patterns for Different Flow Conditions
Choi, Sung-Yoon ; Oh, Se-Jong ;
International Journal of Aeronautical and Space Sciences, volume 3, issue 1, 2002, Pages 74~85
DOI : 10.5139/IJASS.2002.3.1.074
The numerical experiment has been conducted to investigate the unsteady shock wave reflecting phenomena. The cell-vertex finite-volume, Roe's upwind flux difference splitting method with unstructured grid is implemented to solve unsteady Euler equations. The
-order Runge-Kutta method is applied for time integration. A linear reconstruction of the flux vector using the least-square method is applied to obtain the
-order accuracy for the spatial derivatives. For a better resolution of the shock wave and slipline, the dynamic grid adaptation technique is adopted. The new concept of grid adaptation technique, which is much simpler than that of conventional techniques, is introduced for the current study. Three error indicators (divergence and curl of velocity, and gradient of density) are used for the grid adaptation procedure. Considering the quality of the solution and the numerical efficiency, the grid adaptation procedure was updated up to
level at every 20 time steps. For the convenience of comparison with other experimental and analytical results, the case of interaction between the straight incoming shock wave and a sharp wedge is simulated for various flow conditions. The numerical results show good agreement with other experimental and analytical results, in the shock wave reflecting structure, slipline, and the trajectory of the triple points. Some critical cases show disagreement with the analytical results, but these cases also have been proven to show hysteresis phenomena.
Adaptive Kalman Filter Design for an Alignment System with Unknown Sway Disturbance
Kim, Jong-Kwon ; Woo, Gui-Aee ; Cho, Kyeum-Rae ;
International Journal of Aeronautical and Space Sciences, volume 3, issue 1, 2002, Pages 86~94
DOI : 10.5139/IJASS.2002.3.1.086
The initial alignment of inertial platform for navigation system was considered. An adaptive filtering technique is developed for the system with unknown and varying sway disturbance. It is assumed that the random sway motion is the second order ARMA(Auto Regressive Moving Average) model and performed parameter identification for unknown parameters. Designed adaptive filter contain both a Kalman filter and a self-tuning filter. This filtering system can automatically adapt to varying environmental conditions. To verify the robustness of the filtering system, the computer simulation was performed with unknown and varying sway disturbance.
Effects of Surface Radiation on the Unsteady Natural Convection in a Rectangular Enclosure
Baek, Seung-Wook ; Kim, Taig-Young ;
International Journal of Aeronautical and Space Sciences, volume 3, issue 1, 2002, Pages 95~104
DOI : 10.5139/IJASS.2002.3.1.095
Numerical solution of the full Navier-Stokes equation as well as the energy equation has been obtained for the unsteady natural convection in a rectangular enclosure. One side wall was maintained at very high temperature simulating fires. Especially the effect of surface radiation was taken into account. While the enclosed air was assumed to be transparent, the internal walls directly interacted one another through the surface radiation. Due to a significant temperature difference in the flow field, the equation of state was used instead of the Boussinesq approximation. It was found that the rapid heating of the adiabatic ceiling and floor by the incoming radiation from the hot wall made the evolution at thermo-fluid field highly unstable in the initial period. Therefore, the secondary cells brought about at the floor region greatly affected the heat transfer mechanism inside the enclosure. The heat transfer rate was augmented by the radiation, resulting in requiring less time for the flow to reach the steady state. At the steady state neglecting radiation two internal hydraulic jumps were clearly observed in upper/left as well as in lower/right comer. However, the hydraulic jump in the lower/right comer could not be observed for the case including radiation due to its high momentum flow over the bottom wall. Radiation resulted in a faster establishment of the steady state phenomena.