• Journal of Aerospace System Engineering
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• v.1 no.3
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• pp.37-42
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• 2007

The flight safety system for the satellite launch vehicles is required in order to minimize the risk due to launch vehicle failure. For prompt and reliable decision of flight termination, the flight safety system usually uses multiple sensors to estimate launch vehicle's flight trajectory. In that case, multiple types of observed tracking data makes it difficult to identify the flight termination condition. Therefore, a fusion tracking filter handling the multiple tracking data is necessary for the flight safety system. This research developed a simulation software for generating multiple types of launch vehicle tracking data, and then processed the data with fusion filters.

• Journal of Korea Society of Industrial Information Systems
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• v.20 no.5
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• pp.1-11
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• 2015

This paper is focused on how the trajectory of launch vehicle could be optimally estimated by the quadratic regression of trajectory data mining for the operation of telemetry ground system in NARO space center during real-time. To receive the telemetry data, the telemetry ground system has to track the space launch vehicle without tracking loss, and it is possible by the well-designed algorithm to estimate a flight position in real-time. For this reason, the quadratic regression model instead of interpolation was considered to estimate the exact position data of launch vehicle and the improvement of antenna performance. For analysis, the real trajectory data which had been logged during NARO 1st launch mission were used, the estimation result of launcher current position was analyzed by the mathematical modeling. In conclusion, the algorithm using quadratic regression based on trajectory data mining showed the better performance than previous interpolation algorithm to estimate the next flight position and the antenna driving performance.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.2
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• pp.115-124
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• 2015

A methodology is proposed to estimate a trajectory of a flying target and its velocity using the time and frequency analysis of the acoustic signal. The measurement of sound emitted from a flying acoustic source with a microphone above a ground shall receive both direct and ground-reflected sound waves. For certain frequency contents, the destructive interference happens in received signal waveform reflected path lengths are in multiple integers of direct path length. This phenomenon is referred to as the acoustical mirror effect and it can be observed in a spectrogram plot. The spectrogram of acoustic measurement for a flying vehicle measurement shows several orders of destructive interference curves. The first or second order of curve is used to find the best approximate path by using nonlinear least-square method. Simulated acoustic signal is generated for the condition of known geometric of a sensor and a source in flight. The estimation based on cepstrogram analysis provides more accurate estimate than spectrogram.

• Journal of Advanced Navigation Technology
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• v.12 no.4
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• pp.295-303
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• 2008

Malfunction of satellite launch vehicles with high speed and long range can be a major concern for operations. Flight safety system that monitor the trajectory and identify any failure of the launch vehicles. Tracking filters for the flight safety systems are different from common tracking filters since filter reliability is more emphasized than accuracy. Reliable estimation of instantaneous impact points requires reliable velocity estimates as well as reliable position estimates. A fusion filter for a flight safety system was developed with the tracking sensor models for the Korea Satellite Launch Vehicle I. The fusion filter performances were evaluated by analyzing the trajectory and instantaneous impact point estimates.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.512-521
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• 2017

This paper reports development process of a university-based sounding rocket using simplified hybrid rocket propulsion system for low-altitude flight application. A hybrid propulsion system was tried to be designed with as few components as possible for more economical, simpler and safer propulsion system, which is essential for the small scale sounding rocket operation as a CanSat carrier. Using blow-down feeding system and catalytic ignition as combustion starter, 250 N class hybrid rocket system was composed of three components: a composite tank, valves, and a thruster. With a composite tank filled with both hydrogen peroxide($H_2O_2$) as an oxidizer and nitrogen gas($N_2$) as a pressurant, the feeding pressure was operated in blowdown mode during thruster operation. The $MnO_2/Al_2O_3$ catalyst was fabricated for propellant decomposition, and ground test of propulsion system showed the almost theoretical temperature of decomposed $H_2O_2$ at the catalyst reactor, indicating sufficient catalyst efficiency for propellant decomposition. Auto-ignition of the high density polyethylene(HDPE) fuel grain successfully occurred by the decomposed $H_2O_2$ product without additional installation of any ignition devices. Performance test result was well matched with numerical internal ballistics conducted prior to the experimental propulsion system ground test. A sounding rocket using the developed hybrid rocket was designed, fabricated, flight simulated and launch tested. Six degree-of-freedom trajectory estimation code was developed and the comparison result between expected and experimental trajectory validated the accuracy of the developed trajectory estimation code. The fabricated sounding rocket was successfully launched showing the effectiveness of the simplified hybrid rocket propulsion system.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.3
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• pp.5-12
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• 2008

This paper presents the features of an impact angle constrained open-loop optimal trajectory which is given by a function of initial conditions and optimal guidance gains. Using missile motion described by linearized kinematic equations and a proper form of performance index, an inverse optimal problem is suggested to investigate the gains related to the performance index. The flight trajectory and time-to-go can be shaped in terms of the optimal guidance gains. The results are evaluated by 3-DOF simulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.5
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• pp.385-392
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• 2018

This paper suggests a new method to estimate the roll and pitch damping moment coefficients of a flying disc through sensor data from the onboard IMU module. This method can be easily performed than wind tunnel or computational fluid dynamics methods because it estimates aerodynamic coefficients simply after accumulating the inertial data through several repeated flight experiments. Estimated coefficients are applied to a simulator which is based on the flight dynamics of a flying disc. Finally, the predicted flight trajectory is compared with the true position provided by GPS, which demonstrated the validity of the proposed estimation method.

• Electronics and Telecommunications Trends
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• v.36 no.2
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• pp.1-11
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• 2021

As sensors such as Inertial Measurement Unit, cameras, and Light Detection and Rangings have become cheaper and smaller, research has been actively conducted to implement functions automating micro aerial vehicles such as multirotor type drones. This would fully enable the autonomous flight of drones in the real world without human intervention. In this article, we present a survey of state-of-the-art development on autonomous drones. To build an autonomous drone, the essential components can be classified into pose estimation, environmental perception, and obstacle-free trajectory generation. To describe the trend, we selected three leading research groups-University of Pennsylvania, ETH Zurich, and Carnegie Mellon University-which have demonstrated impressive experiment results on automating drones using their estimation, perception, and trajectory generation techniques. For each group, we summarize the core of their algorithm and describe how they implemented those in such small-sized drones. Finally, we present our up to date research status on developing an autonomous drone.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.10
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• pp.1012-1019
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• 2010

In this paper, The flight data processing system was designed for multiple target flight test. For flight data processing, multiple target grouping, data fusion processing, and data slaving processing were performed and, as a data fusion filter, centralized, and federated Kalman filters were designed. A centralized kalman filter was modified in order to improve the vehicle's low altitude measurement using radar's SNR and estimation process. From the testing of multiple target missile, it confirmed flight trajectory measurement was improved in low altitude area and the beginning stage of vehicle.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.3
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• pp.234-243
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• 2015

It is required to have the capability to predict the impact point of the ballistic target in order to assign the firing unit with high engagement possibility for the interception in the ballistic target defense systems. In this paper, a novel method is proposed to predict the impact point of the ballistic target using a flight phase discrimination algorithm given the insufficient measurements on the partial trajectory. The flight of a ballistic target is composed of a boost phase and a ballistic phase with different dynamics. The flight phase is discriminated by using the normalized innovation distance between measurements and a priori estimated measurements. The threshold and tolerance in the flight phase discrimination are determined from the probabilistic characteristics of the estimation error. Monte Carlo simulations are performed to verify the proposed method.