• Proceedings of the KSME Conference
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• 2007.05a
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• pp.648-653
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• 2007

In this study, we have generated fatigue load spectrum that is using to prediction of life time for the helicopter rotor blades. We derive utility helicopter missions for the sake of generating load spectrum. Helix and Felix are standard loading sequences which relate to the main rotors of helicopters with articulated and semi-rigid rotors respectively. We got scale factors which is applied to specific case and it did be obtained through the finite element analysis tools. The fatigue life of the rotor blade is estimated by using MSC/Fatigue. We suggest that generated our fatigue load spectrum in conjunction with small utility helicopter should use to rotor blade fatigue test of the korea helicopter program.

• The Journal of Korea Robotics Society
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• v.10 no.3
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• pp.133-138
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• 2015

This paper presents a modified task structure of coupled-constraints consensus based bundle algorithm especially to resolve the cooperative transportation problem. The cooperative transportation mission has various types of constraints. A modified framework to generate activities and subtasks to solve time and task constraints of the transportation mission by using coupled-constraints consensus based bundle algorithm is suggested. In this paper modifications on task structure, reward function and arrival time calculation are suggested to handle the constraints of cooperative transportation mission.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.16 no.4
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• pp.63-68
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• 2008

Compared with past, helicopters have remarkably high level of safety and accidents due to mechanical defects are decreased about 15%. Most of their duties, however, are to commit at duty area which is hard to access. Because of them, collision probability is high and also has relatively higher accident rates than other aircraft with special mission. A result of analysis is that accident rate is relative high with prevention of disasters, putting out a fire and crop-dusting missions under 500ft. In addition, most of accidents are related with human factors. According to this, it is required to pilots who carry these mission that safety education and detailed analysis about their mission.

• Journal of Astronomy and Space Sciences
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• v.37 no.3
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• pp.187-197
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• 2020

In order to avoid the high cost and high risk of demonstration mission of rendezvous-docking technology, missions using nanosatellites have recently been increasing. However, there are few successful mission cases due to many limitations of nanosatellites like small size, power limitation, and limited performances of sensor, thruster, and controller. To improve the probability of rendezvous-docking mission success using nanosatellite, a rendezvous-docking phase analysis tool for nanosatellites is developed. The tool serves to analyze the relative position and attitude control of the chaser satellite at the docking phase. In this tool, the Model Predictive Controller (MPC) is implemented as a controller, and Extended Kalman Filter (EKF) is adopted as a filter for noise filtering. To verify the performance and effectiveness of the developed tool for nanosatellites, simulation study was conducted. Consequently, we confirmed that this tool can be used for the analysis of relative position and attitude control for nanosatellites in the rendezvous-docking phase.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.4
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• pp.622-628
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• 2012

This paper proposes an environment monitoring algorithm using a behavior-based multiple robot system. This paper handles an escort and a boundary-tracking especially. Unlike previous research works, the proposed environment monitoring system which is based on the behavior-based multiple robot control allows the system to employ the reusable code and general algorithm. Also, the proposed method can be applied to cheaper process with low performances. In the proposed method, escort and boundary-tracking missions are constructed by weighted sum of predefined basic behaviors after redefining the basic behaviors in previous works and introducing the novel basic behavior. Simulation results of the proposed method are included to demonstrate the practical application of the proposed algorithm.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.6
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• pp.122-129
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• 2010

The military vehicles are necessary to perform various war battle missions but in reality they are not as convenient as the civil vehicles. Thus, it is problematic regarding the satisfaction about convenience, operation, and performances of military vehicles. Since most of military vehicles used in Korea were made by bench-marking the models of United States developed in the latter half of 1970's. It is question whether the current military vehicles can provide the functions and expected performance fully or not if we do not study what the user friendly military vehicles are. This article report soldiers' user satisfaction survey on military vehicles and provide arguments on the priority decision based on users' requirements. Future direction for the development of military vehicles is discussed.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.2
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• pp.14-25
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• 2006

This paper is focused on designing an implementable control law to perform spacecraft various missions using momentum exchange devices such as reaction wheels(RWs) and control moment gyros(CMGs). A compact equation of motion of a spacecraft installed with various momentum exchange devices is derived in this paper. A hybrid control law is proposed for precision attitude control of agile spacecraft. The control law proposed in this paper allocates control torque to the CMGs and the RWs adequately to satisfy the precision attitude control and large angle maneuver simultaneously. The saturation problem of reaction wheels and the singularity problem of control moment gyros are considered. The problems are successfully resolved by using the proposed hybrid closed loop control law. Finally, the proposed hybrid control law is demonstrated by numerical simulations.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.2
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• pp.145-154
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• 2006

Many kinds of unmanned aerial vehicles (UAVs) have been developed for a few decades and some of them are now in operational use. Although each UAV as well as a piloted aircraft might have restrictions to execute some tasks simultaneously or to carry some payloads, one with an automatic chase aircraft might have the potential of multi-capabilities to conduct a variety of missions or to carry more storages. This paper introduces a chase UAV control system to enhance a leader (reference) aircraft capability which has storage restriction. The automatic chase guidance and control system will be introduced with the pure pursuit guidance law combined with relative velocity error corrections, and a dynamic inversion technique in order to generate the guidance forces.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.47-47
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• 2003

Analytical formulae are presented to approximate the evolution of the semi major axis, the maneuver time, and the final mass fraction for low thrust orbital transfers with circular initial orbit, circular target orbit, and constant thrust directed either always along or always opposite the velocity vector. For comparison, the associated results for high-thrust transfers, i.e. the two-impulse Hohmann transfer, are summarized. All results are implemented in a computer code designed to analyze planar planetary and interplanetary space missions. This implementation yields fast and reasonably accurate approximations to trajectory performance boundaries. Consequently, the approach can provide trajectory analysis for each spacecraft configuration during the conceptual space mission design phase. As an example, a mission from Low-Earth Orbit (LEO) to Jupiter's moon Europa is analyzed.

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.245-250
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• 1998

Attitude determination and control of satellite is important component which determines the accomplish satellite missions. In this study, attitude control using reaction wheels and momentum dumping of wheels are considered. Attitude control law is designed by Sliding control and LQR. Attitude maneuver control law is obtained by Shooting method. Wheels momentum dumping control law is designed by Bang-Bang control. Four reaction wheels are configurated for minimized the electric power consumption. Wheels control torque and magnetic moment of magnetic torquer are limited.