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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 4, Issue 2 - Nov 2003
Volume 4, Issue 1 - May 2003
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A New Method of determining Initial Conditions for Satellite Formation Flying
Lim, Hyung-Chul ; Bang, Hyo-Choong ; Park, Kwan-Dong ; Park, Pil-Ho ;
International Journal of Aeronautical and Space Sciences, volume 4, issue 2, 2003, Pages 1~8
DOI : 10.5139/IJASS.2003.4.2.001
Satellite formation flying is the placing micro-satellites with the same mission into nearby orbits to form a cluster. Clohessy-Wiltshire equations are used to describe the relative motion and control strategies between satellites within a cluster, which are known as Hill`s equations. Even though Hill`s equations are powerful in determining initial conditions for the satellite formation flying, they can not accurately express the relative motion under J2 perturbation. Some methods have been developed for the determination of initial conditions to avoid limits of Hill`s equation. This paper gives a new method of determining initial conditions using mean elements. For this research mean elements were transformed to osculating elements using Brouwer`s theory and the orbit was propaeated with the consideration of J2-J8 to get a relative position. The results show that satellites within a cluster are maintained in the desired boundary for long period and the method is effective on a fuel saving for satellite formation flying.
Crack Analysis of Piezoelectric Material Considering Bounded Uncertain Material Properties
Kim, Tae-Uk ; Shin, Jeong-Woo ;
International Journal of Aeronautical and Space Sciences, volume 4, issue 2, 2003, Pages 9~16
DOI : 10.5139/IJASS.2003.4.2.009
Piezoelectric materials are widely used to construct smart or adaptive structures. Although extensive efforts have been devoted to the analysis of piezoelectric materials in recent years, most researches have been conducted by assuming that the material properties are fixed and have no uncertainties. Intrinsically, material properties have a certain amount of scatter and such uncertainties can affect the performance of component. In this paper, the convex modeling is used to consider such uncertainties in calculating the crack extension force of piezoelectric material and the results are compared with the one obtained via the Monte Carlo simulation. Numerical results show that crack extension forces increase when uncertainties considered, which indicates that such uncertainties should not be ignored for reliable lifetime prediction. Also, the results obtained by the convex modeling and the Monte Carlo simulation show good agreement, which demonstrates the effectiveness of the convex modeling.
Thermal Analysis on a Satellite Box during Launch Stage by Analytical Solution
Choi, Joon-Min ; Kim, Hui-Kyung ; Hyun, Bum-Seok ;
International Journal of Aeronautical and Space Sciences, volume 4, issue 2, 2003, Pages 17~25
DOI : 10.5139/IJASS.2003.4.2.017
Simple methods are developed to predict temperatures of a satellite box during launch stage. The box is mounted on outer surface of satellite and directly exposed to space thermal environment for the time period from fairing jettison to separation. These simple methods are to solve a 1st order ordinary differential equation (ODE) which is simplified from the governing equation after applying several assumptions. The existence of analytical solution for the 1st order ODE is determined depending on treatment of time-dependent molecular heating term. Even for the case that the analytical solution is not available due to the time dependent term, the 1st order ODE can be solved by relatively simple numerical techniques. The temperature difference between two different approaches (analytical and numerical solutions) is relatively small (Jess than
along the time line) when they are applied to STSAT-I launch scenario. The present methods can be generally used as tools to quickly check whether a satellite box is safe against space environment during the launch stage for the case that the detailed thermal analysis is not available.
Real-time midcourse guidance with consideration of the impact condition
Song, Eun-Jung ; Joh, Mi-Ok ;
International Journal of Aeronautical and Space Sciences, volume 4, issue 2, 2003, Pages 26~36
DOI : 10.5139/IJASS.2003.4.2.026
The objective of this study is to enhance neural-network guidance to consider the impact condition. The optimal impact condition in this study is defined as an head-on attack. Missile impact-angle error, which is a measure of the degree to which the missile is not steering for a head-on attack, can also have an influence on the final miss distance. Therefore midcourse guidance is used to navigate the missile, reducing the deviation angle from head on, given some constraints on the missile g performance. A coordinate transformation is introduced to simplify the three-dimensional guidance law and, consequently, to reduce training data. Computer simulation results show that the neural-network guidance law with the coordinate transformation reduces impact-angle errors effectively.
A Study on HAUSAT-1 Satellite Fault-Tolerant System Architecture Design
Kim, Young-Hyun ; Chang, Young-Keun ;
International Journal of Aeronautical and Space Sciences, volume 4, issue 2, 2003, Pages 37~50
DOI : 10.5139/IJASS.2003.4.2.037
A next generation small satellite HAUSAT-1, the first picosatellite developed in Korea, is being developed as one of the international CubeSat program by Space System Research Lab. of Hankuk Aviation University. A fault-tolerant incremental design methodology has been addressed in this paper. In this study, the effect of system redundancy on reliability was in details analyzed in accordance with the implementation of fault-tolerant system. Four different system recovery levels are proposed for HAUSAT-1 fault-tolerant system optimization. As a result, the HAUSAT-1 fault-tolerant system architecture design and reliability analysis has acquired about 11% reliability improvement.
Effect of Mixture Ratio Variation near Chamber Wall in Liquid Rocket Engine
Han, Poong-Gyoo ; Kim, Kyoung-Ho ;
International Journal of Aeronautical and Space Sciences, volume 4, issue 2, 2003, Pages 51~60
DOI : 10.5139/IJASS.2003.4.2.051
An experimental research program is being undertaken to develop a regeneratively-cooled experimental thrust chamber of liquid rocket engine using liquefied natural gas and liquid oxygen as propellants. Prior to firing test using a regenerative cooling with liquefied natural gas in this program, several firing tests were conducted with water as a coolant. Experimental thrust chambers with a thrust of about 10tf were developed and their firing test facility was built up. Injector used in the thrust chamber was of shear-coaxial type appropriate for propellants of gas and liquid phase and cooling channels are of milled rectangular configuration. Periodical variation of the soot deposition and discoloration was observed through an eyes` inspection on the inner wall of a combustion chamber and a nozzle after each firing test, and an intuitive concept of the periodical variation of mixture ratio near the inner wall of a combustion chamber and a nozzle at once was brought about and analyzed quantitatively. Thermal heat flux to the coolant was calculated and modified with the periodical variation model of mixture ratio, and the increment of coolant temperature at cooling channels was compared with measured one.
Study for the Information Operations for Long Unattended Periods of Time at the Space System
Kim, Han-Woong ;
International Journal of Aeronautical and Space Sciences, volume 4, issue 2, 2003, Pages 61~68
DOI : 10.5139/IJASS.2003.4.2.061
The space systems are being operated in a uncertain space environment and are desired to have autonomous capability for long periods of time without frequent telecommunications with the ground station. At the same time, requirements for new set of satellite system set of projects/systems calling for "autonomous" operations for long unattended periods of time are emerging. Since, by the nature of space systems, it is desired to perform its mission flawlessly and also it is of extreme importance to have fault-tolerant sensors and actuators for the purpose of validating science measurement data for the mission success. This studies focused on the identification/demonstration of critical technology innovations that will be applied to the Validation Control System.
Least Squares Based PID Control of an Electromagnetic Suspension System
Park, Yon-Mook ; Tahk, Min-Jea ; Nam, Myeong-Ryong ; Seo, In-Ho ; Lee, Sang-Hyun ; Lim, Jong-Tae ;
International Journal of Aeronautical and Space Sciences, volume 4, issue 2, 2003, Pages 69~78
DOI : 10.5139/IJASS.2003.4.2.069
In this paper, we develop the so-called functional test model for magnetic bearing wheels. The functional test model developed in this paper is a kind of electromagnetic suspension systems and has three degree of freedom, which consists of one axial suspension from gravity and the other two axes gimbaling capability to small angle, and does not include the motor. For the control of the functional test model, we derive the optimal electromagnetic forces based on the least squares method, and use the proportional-integral derivative controller. Then, we develop a hardware setup, which mainly consists of the digital signal processor and the 12-bit analog-to-digital and digital-to-analog converters, and show the experimental results.
Techniques For Control Acoustic Response of Corner-Pinned Rectangular Plate Using Piezo-electric Actuator
Jung, Do-Hee ; Kim, Woo-Young ; Lee, Sang-Kee ; Park, Seen-Ok ;
International Journal of Aeronautical and Space Sciences, volume 4, issue 2, 2003, Pages 79~87
DOI : 10.5139/IJASS.2003.4.2.079
Acoustic response control of a comer-pinned plate using piezoelectric wafers was studied, both theoretically and experimentally. Three different sizes of aluminum alloy plates were used and available ball joints were employed to hold the plate at the four comers. The plate with the largest aspect ratio showed the largest and most clear responses to the acoustic excitation in the range of frequencies (0~200Hz), and sound pressure levels (80~100dB) as predicted. The reduction of the acoustic response of the plate by piezoelectric actuator was very significant, more than expected, but abatement of the sound transmission through the plate was only slightly altered by the piezoelectric actuator. This work is an original work extending earlier work with doors excited by acoustic fields. The important difference is the used of ball joints to simulate the joints.
Design of Ka-band Satellite Ground Station Antenna/RF System
Lee, Jeom-Hun ; Lee, Seong-Pal ; Oh, Seung-Hyeub ;
International Journal of Aeronautical and Space Sciences, volume 4, issue 2, 2003, Pages 88~94
DOI : 10.5139/IJASS.2003.4.2.088
This paper describes the design of the Ka-band Antenna/RF system, which was developed for the experiment of the high-speed satellite communications with geostationary satellite. The design issues described here are the ka-band characteristics for having an optimum performance. and the system characteristic for having a reliable and an extensional operation.