• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.2
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• pp.285-293
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• 2024

This paper describes the interception using fine fragments and particles to hypersonic vehicles which have a vulnerability in thermal and pressure during glide-phase flight. This interception concept is based on the fast relative velocity and the flight vulnerability of hypersonic vehicles. For the density calculation of fragmentation and particle in interception, error analysis of end-phase was performed including radar, intercept missile and target maneuvering errors. In relation to the vulnerability and error analysis, the penetration characteristics of fine fragments in high temperature were analyzed. Presented the interception in glide-phase could be applied to the concept of horizontal multi-layer defense to hypersonic vehicles.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.2
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• pp.63-70
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• 2012

The collision-free flight planning method based on the extended collision map is proposed for cooperation of multiple unmanned aerial vehicles (UAVs) in a common 3-dimensional workspace. First, a UAV is modeled as a sphere, taking its 3-D motions such as rolling into consideration. We assume that after entering the common workspace, the UAVs move along their straight paths until they depart from the workspace, and that the priorities of the UAVs are determined in advance. According to the assumptions, the collision detection problem between two spheres in $R^3$ can be reduced into the collision detection problem between a circle and a line in $R^2$. For convenience' sake and safety, the collision regions are approximated by collision boxes. Using the collision boxes, the entrance times of the UAVs are scheduled for collision avoidance among the UAVs. By this way, all UAVs can move in the common workspace without collisions with one another. For verifying the effectiveness of the proposed flight planning method, the simulation with 12 UAVs is carried out.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.1
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• pp.1-6
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• 2015

This paper investigates the longitudinal flight dynamics and stability of flapping-wing micro air vehicles. Periodic external forces and moments due to the flapping motion characterize the dynamics of this system as NLTP (Non Linear Time Periodic). However, the averaging theorem can be applied to an NLTP system to obtain an NLTI (Non Linear Time Invariant) system which allows us to use a standard eigen value analysis to assess the stability of the system with linearization around a reference point. In this paper, we investigate the dynamics and stability of a hawkmoth-scale flapping-wing air vehicle by establishing an LTI (Linear Time Invariant) system model around a hovering condition. Also, a direct time integration of full nonlinear equations of motion of the flapping-wing micro air vehicle is conducted to see how the longitudinal flight dynamics appear in the time domain beyond the reference point, i.e. hovering condition. In the study, the flapping-wing air vehicle exhibited three distinct dynamic modes of motion in the longitudinal plane of motion: two stable subsidence modes and one unstable oscillatory mode. The unstable oscillatory mode is found to be a combination of a pitching velocity state and a forward/backward velocity state.

• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.1-2
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.826-831
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• 2004

Recently, studies have been carried out to develop unmanned Micro Air Vehicles(MAVs) that can search and monitor inside buildings during urban warfare or rescue operations in hazardous environments. However, existing fixed-wing and rotary-wing MAVs cannot travel at extremely low or high speeds, hover in place, or change directions instantly. This has lead researches to search for other flight methods that could overcome those drawbacks. Insect flight principles and its applications to MAVs are being studied as an alternative flight method. To take flight, insects flap and rotate their wings. These wing motions allow for high maneuverability flight such as hovering, vertical take off and landing, and quick acceleration and deceleration. This paper proposes a method for designing a mechanism that reproduces hovering insect flight, the basis for all other forms of insect flight. The design of a mechanism that can reproduce the motion that causes maximum lift is proposed, the required specifications are calculated, and a method for reproducing hovering insect flight with a single motor is presented. Also, feasibility of the design was confirmed by simulation.

• International Journal of Aeronautical and Space Sciences
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• v.5 no.1
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• pp.57-63
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• 2004

UAV(Unmanned Aerial Vehicle) has become one of the most popularmilitary/commercial aerial robots in the new millennium. In spite of all theadvantages that UAVs inherently have, it is not an easv job to develop a UAVbecause it requires very systematic and complete approaches in full developmentenvelop. The ground test and evaluation phase has the utmost importance in thesense that a well-developed system can be best verified on the ground. In addition,many of the aircraft crashes in the flight tests were resulted from the incompletedevelopment procedure. In this research, a verification procedure of the wholeairbome integrated system was conducted including the flight management system.An airbome flight control computer(FCC) senses the extemal environment from thepehpheral devices and sends the control signal to the actuating system using theassigned control logic and flight test strategy. A ground test station controls themission during the test while the downlink data are transferred from the flightmanagement computer using the serial communication interface. The pilot controlbox also applies additional manual actuating commands. The whole system wastested/verified on the wind-tunnel system, which gave a good pitch controlperformance with a preUspecified flight test procedure. The ground test systemguarantees the performance of fundamental functions of airbome electronic systemfor the future flight tests.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.463-467
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• 2005

In this paper, the guidance law applicable to formation flight of UAV in three-dimensional space is proposed. The concept of miss distance, which is commonly used in the missile guidance laws, and Lyapunov stability theorem are effectively combined to obtain the guidance commands of the wingmen. The propose guidance law is easily integrated into the existing flight control system because the guidance commands are given in terms of velocity, flight path angle and heading angle to form the prescribed formation. In this guidance law, communication is required between the leader and the wingmen to achieve autonomous formation. The wingmen are only required the current position and velocity information of the leader vehicle. The performance of the proposed guidance law is evaluated using the complete nonlinear 6-DOF aircraft system. This system is integrated with nonlinear aerodynamic and engine characteristics, actuator servo limitations for control surfaces, various stability and control augmentation system, and autopilots. From the nonlinear simulation results, the new guidance law for formation flight shows that the vehicles involved in formation flight are perfectly formed the prescribed formation satisfying the several constraints such as final velocity, flight path angle, and heading angle.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.2
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• pp.137-147
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• 2015

Hypersonic vehicles exhibit distinct dynamic and static characteristics, such as unstable dynamics, strict altitude angle limitation, large control bandwidth, and unconventional system sensitivity. In this study, compromise relations between the dynamic features and static performances for hypersonic vehicles are investigated. A compromise optimal design for hypersonic vehicles is discussed. A parametric model for analyzing the dynamic and static characteristics is established, and then the optimal performance indices are provided according to the different design goals. A compromise optimization method to balance the dynamic and static characteristics is also discussed. The feasibility of this method for hypersonic vehicles is demonstrated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.3
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• pp.280-287
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• 2010

The first Korean satellite launch vehicle, KSLV-I(Korea Space Launch Vehicle-I), was launched for its first flight test on Aug. 25, 2009 from Naro Space Center located in south Jolla province. Because launch vehicles usually fly long range with large amount of propellants aboard, preparation of countermeasures against potential malfunctions during flight is essential in launch operation. In this paper, the flight safety operation, prepared to guarantee flight safety during launch operation of KSLV-I, is presented. Prior to flight test, flight safety analysis is performed to estimate associated risk levels quantitatively, and during flight, flight safety systems are operated to cope with any risky situations. Real-time flight monitoring including computation of instantaneous impact point using tracking data is executed normally and the flight test is completed without activation of flight termination system.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.4
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• pp.551-564
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• 2016

High-speed flight vehicles (HSFVs) such as space launch vehicles and missiles undergo severe dynamic loads which are generated during the launch and in in-flight environments. A typical vehicle is composed of thin plate skin structures with high-performance electronic units sensitive to such vibratory loads. Such lightweight structures are then exposed to external dynamic loads which consist of random vibration, shock, and acoustic loads created under the operating environment. Three types of dynamic loads (acoustic loads, rocket motor self-induced excitation loads and aerodynamic fluctuating pressure loads) are considered as major components in this study. The estimation results are compared to the design specification (MIL-STD-810) to check the appropriateness. The objective of this paper is to study an estimation methodology which helps to establish design specification for the dynamic loads acting on both vehicle and electronic units at arbitrary locations inside the vehicle.