• Journal of Astronomy and Space Sciences
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• v.13 no.2
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• pp.163-172
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• 1996

The objective of this paper is to show how digital signal processing experiment(DSPE) was designed and to present its experimental results in orbit and on the ground. The multi-missional and flexible DSPE was designed in a reliable manner. Among several experiments executed in orbit and on the ground, a high-speed(19.2kbps) software modulator experiment was discussed in this paper. A 32bit floating-type TMS320C30, which was developed for commercial purposes, was used on LEO micro-satellites, KITSAT-1 and KITSAT-2. This digital signal processor(DSP) can be applied to the various payloads of the next generation satellites.

• Journal of Astronomy and Space Sciences
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• v.33 no.3
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• pp.211-219
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• 2016

Korea's lunar exploration project includes the launching of an orbiter, a lander (including a rover), and an experimental orbiter (referred to as a lunar pathfinder). Laser altimeters have played an important scientific role in lunar, planetary, and asteroid exploration missions since their first use in 1971 onboard the Apollo 15 mission to the Moon. In this study, a laser altimeter was proposed as a scientific instrument for the Korean lunar orbiter, which will be launched by 2020, to study the global topography of the surface of the Moon and its gravitational field and to support other payloads such as a terrain mapping camera or spectral imager. This study presents the baseline design and performance model for the proposed laser altimeter. Additionally, the study discusses the expected performance based on numerical simulation results. The simulation results indicate that the design of system parameters satisfies performance requirements with respect to detection probability and range error even under unfavorable conditions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.1000-1005
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• 2003

The shock separation test simulates the environmental effects of the spacecraft separation from launch vehicle. The shock separation test for a structural model of KOMPSAT-Ⅱ(Korea Multi-Purpose SATellite Ⅱ) was performed in SITC(Satellite Integration ＆ Test Center) launch environmental test hall at KARI(Korea Aerospace Research Institute) to verify the shock test requirement of the spacecraft, to predict the induced acceleration responses on the primary structures and payloads by the explosion of pyre-lock and to perform mechanical fit check. The spacecraft with S/A was mated vertically to LV(Launch Vehicle) adapter simulator via a clamp band, then hoisted and suspended above a foam test bed by four isolation springs secured to the spacecraft hoist fittings to isolate the payload platform shock wave from the sling elements. For separation process, real pyre-devices were used and the time response signals from 60 accelerometers installed on the interested points was acquired and recorded. The SRS responses for each response channels were calculated and the achieved SRS's on the separation plane was reviewed and evaluated in comparison to the ICD(Interface Control Document) value.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.4
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• pp.391-397
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• 2016

Vibration disturbances induced by the reaction wheels can severely degrade the performance of high precision payloads on board satellites with high pointing stability requirements. The unwanted disturbances produced by the reaction wheels are composed of fundamental harmonic disturbances due to the flywheel imbalance and sub/higher harmonic disturbances due to bearing irregularities, motor imperfections and so on. Because the wheel speed is constantly changed during the operation of a reaction wheel, the vibration disturbance induced by the reaction wheels can magnify the satellite vibration when the rotating frequency of wheel meets the natural frequency of satellite structure. In order to provide an effective isolation of the reaction wheel disturbances, isolation performance of a hybrid vibration isolator is investigated. In this paper, hybrid vibration isolator that combines passive and active components is developed and its hybrid isolation performance using notch filter control is evaluated in single-axis. The hybrid isolation performance using notch filter control show additional performance improvement compared to the results using only passive components.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.7
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• pp.517-524
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• 2014

Micro-vibration induced by on-board equipments such as fly-wheel and cryogenic cooler with mechanical moving parts affects the image quality of high-resolution observation satellite. Micro-vibration isolation system has been widely used for enhancing the pointing performance of observation satellites. In general, the micro-vibration isolation system requires a launch locking mechanism additionally to guarantee the structural safety of mission payloads supported by the isolation system with low stiffness under launch environment. In this study, we propose a passive launch and on-orbit vibration isolation system using shape memory alloy mesh washers for the micro-vibration isolation of spaceborne compressor, which does not require the additional launch locking mechanism. The basic characteristics of the isolator were measured in static and free vibration tests of the isolator, and a simple equivalent model of the isolator was proposed. The effectiveness of the isolator design in a launch environment was demonstrated through sine vibration, random vibration and shock tests.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.2
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• pp.121-128
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• 2011

As high precision industries such as semiconductor, TFT-LCD manufacturing and MEMS continue to grow, the demand for higher DOF precision stages has been increasing. In general, the stages should accommodate a prescribed range of payloads in order to position various precision manufacturing/inspection instruments. Therefore a nonlinear controller using sliding motion is developed, which bears mass perturbation and makes the upper plate of the stage move in 6 DOF. For the application of the nonlinear control, an observer is also developed based on expected noise covariance. To eliminate the steady state error of step response, integral terms are inserted into the state-space model. The linear term of the controller is designed using optimization scheme in which parameters can be weighted according to their physical significance, whereas the nonlinear term of the controller is designed using trial and error method. A comprehensive simulation study proves that the designed controller is robust against mass perturbation and completely eliminates steady state errors.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.48-53
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• 2014

Rocket, held using the CCA for the mission, a plurality of recording devices, and navigation equipment. In case of a projectile which is entered the water after fired into the air, after performing stages and fairing separated in flight to enter the underwater. It is caused by the explosion of gunpowder mainly, vibration phenomenon of a large transition is induced structurally very, also on entering the water, have a significant shock structurally separated. If shock is transmitted directly to the CCA through the body, it can be caused malfunction of payloads, resulting in failure of the mission of the projectile. In order to ensure the stability against shock, in this paper, Calculating a target resonacne frequency of the CCA, and verified through modal test and analysis. Maximum acceleration position of CCA is checked by SRS analysis. In addition, effectiveness of shock isolation system through shock analysis.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.10
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• pp.1008-1013
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• 2014

This paper introduces an adaptive anti-sway tracking control algorithm for container cranes with unknown payloads and friction between the trolley and the rail. If the friction effects in the system can be modeled, there is an improved potential to design controllers that can cancel these effects. The proposed control improves the sway suppressing and the positioning capabilities of the trolley and hoisting against uncertain payload and friction. The variable structure controls are first designed based on a class of feedback linearization methods for the stabilization of the under-actuated sway dynamics. The adaptation mechanism are then designed with parameter estimation of unknown payload and friction compensation for the trolley and hoisting, based on Lyapunov stability methods for the accurate positioning and fast attenuation of trolley oscillation due to frictions in the vicinity of the target position. The asymptotic stability of the overall closed-loop system is assured irrespective of variations of rope length. Simulations are shown under various frictions and external winds in the case of no priori information of payload mass.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.241-242
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• 2006

MPEG Surround is an audio coding technology that represents multi-channel audio signal with downmixed audio signal(s) and very low bitrate side information based on Binaural Cue Coding. The side information consists of Inter-Channel Level Difference, Inter-Channel Correlation, and payloads. These two parameters are correspondent to the well-known spatial parameters in psycho-acoustics, Inter-aural Level Difference (ILD) and Inter-Aural Cross Correlation (IACC). Though ICLD is to provide perceptually equivalent ILD to the listener, however, the ILD of the original multi-channel audio signal and that of the MPEG Surround encoded signal was different. The difference between two ILD values is defined as ILD Distortion (ILDD). This paper provides how ILDD can be applied to enhance sound quality in MPEG Surround and how much ILDD is decreased.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.4 s.304
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• pp.25-34
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• 2005

We had research to conduct interrelationships between sensors using postprocessing analysis with the Fuzzy-Kalman Filtering Auto-Correlation about Real Time Simulator data of the NaroSC LCS in case of a fully blind situation scenario. The conducted interrelations are same harmony with relations in scenario. We had analyzed signals of sensors reverse-using a optimization character of Fuzzy-Kalman Filter. As our research conclusion, We had recognized possibilities of signal processing about the KSLV-1, on-board payloads, general equipments of ground support which apply to multi sensor systems.