• 한국항공운항학회:학술대회논문집
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• 2016.05a
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• pp.269-275
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• 2016

This paper considers the arrival, airport and departure capacity as a whole, through which, the network effect between airports is fully emphasized, the flight action is coordinated, and the flight demand pattern is reasonably assigned. The optimization problem of flight queues in multi-airport is studied in detail; the mathematical model of multi-airport opening non-real time flow management in terminal area is established, and related problems such as the parameters, the simplification and the solving of the model are discussed in detail to some extent. Appropriate decision making variables are taken to make the multi-airport network system linear 0-1 integer programming model, thus, the solving of the model is available and the central flow management is realized. The heuristic implicit enumeration presented in this paper can effectively solve this kind of problems. Through the simulation of some airports network system, we not only validate the algorithm presented in this paper, but also give a deep analysis of the results, which would produce reference for later practicable use. The simulation proves that this algorithm offers a good way to settle the problem of multi-airport flight queue optimization in air traffic management automation system in terminal area.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.3
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• pp.264-271
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• 2013

A method of multiple transport-aircraft mission modeling is proposed in order to improve the efficiency of evaluating and optimizing pre-mission plans. To deal with the challenge of multiple transport-aircraft missions, the object-oriented modeling method is utilized. The elements of the mission are decomposed into objects and businesses, And the major mission objects and their important properties are summarized. A complex mission can be broken down into basic business modules such as the ground section and flight section. The business models of loading and fueling services in the ground section are described. The business model of the flight section is composed of an air route and flight profile with the flight equation and the fuel consumption model. The logical relationship of objects and business modules is introduced. The architecture of the simulation system, which includes a database, computation module, graphical user interface (GUI) module, and a result analysis module, is established. A sample case that includes two different plans is provided to verify the model's ability to achieve multi-aircraft composite mission simulation.

• Journal of Astronomy and Space Sciences
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• v.30 no.4
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• pp.291-298
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• 2013

The concept of the satellite formation flight is area where it is actively study with expandability and safety compare to existing satellite. For execution of duty with more safety issue, it needs to consider hot topic of space debris for operation of formation flight. In this paper, it suggests heuristic algorithm to have avoidance maneuver for space debris towards operating flight formation. Indeed it covers, using common software, operating simulation to nearest space environment and not only to have goal of avoidance but also minimizing the usage of fuel and finding optimization for maximizing cycle of formation flight. For improvement on convergence speed of existing heuristic algorithm, it substitute to hybrid heuristic algorithm, PSOGSA, and the result of simulation, it represents the satisfaction of minimum range for successful avoidance maneuver and compare to not using avoidance maneuver, it keeps more than three times of formation maintenance performance. From these, it is meaningful results of showing several success goals like simple avoidance collision and fuel usage and decreasing number of times of maintaining formation maneuver.

• Journal of Advanced Navigation Technology
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• v.20 no.5
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• pp.387-393
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• 2016

To perform realistic air traffic control (ATC) simulation in various air traffic situations, an aircraft dynamic model that is accurate and efficient is required. In this research, an improved five degree of freedom (5-DOF) dynamic model with feedback control and guidance law is developed, which utilizes selected performance data and operational specifications from the base of aircraft data (BADA) and estimations using aircraft design techniques to improve the simulation fidelity. In addition, takeoff weight is estimated based on the aircraft type and flight plan to improve simulation accuracy. The dynamic model is validated by comparing the simulation results with recorded flight trajectories. An ATC simulation system using this 5-DOF model can be used for various ATC related research.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.2
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• pp.135-145
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• 2023

Developing high-fidelity Computational Fluid Dynamics (CFD) simulation methods used to evaluate the airwake characteristics along a flight deck of a large ship, the various kind of data such as actual ship measurement and wind tunnel results are required to verify the accuracy of CFD simulation. Inflow velocity profile at the bow, local unsteady flow field data around the flight deck, and highly reliable wind tunnel data which were measured after reviewing Atmospheric Boundary Layer (ABL) simulation and Reynolds Number effects were also used to determine the key parameters such as turbulence model, time resolution and accuracy, grid resolution and type, inflow condition, domain size, simulation length, and so on in STAR CCM⁺. Velocity ratio and turbulent intensity difference between Full-scale CFD and actual ship measurement at the measurement points show less than 2% and 1.7% respectively. And differences in velocity ratio and turbulence intensity between wind tunnel test and small-scale CFD are both less than 2.2%. Based upon this fact, the selected parameters in CFD simulation are highly reliable for a specific wind condition.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.1
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• pp.69-76
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• 2004

When simulating the mission flight of a fighter equipped with the avionic ECM pod, it is massively required to provide the correct information of threats, to depict the real environment of mission area, and to precisely model the capability of the ECM system. Also, in order to get the reliable results of those simulation, it should be supported the flexible changes of threat environments and the examination of multiple flight paths. This paper presents a software system which is possible to flexible and interactive ECM simulation. This system has capable of the 2D or 3D visualization of virtual battle field, the management of electronic threat data, and the simulation of engagement model.

• International Journal of Aeronautical and Space Sciences
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• v.6 no.2
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• pp.84-96
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• 2005

Helical tip vortex is known as stable vortex structure, however the specific frequency component of far wake perturbation induces the vortex pairing in hover and axial flight. It is expected that the tip vortex pairing phenomena may happen in transition flight and very low advance ratio flight so that inflow may be most nonuniform in the low advance ratio flight. The objectives of this paper are that a tip-vortex instability during the transition from hover into very low advance ratio forward flight is numerically predicted to understand a physics by using a time-marching free-wake method. To achieve the objectives, numerical method is firstly validated in typical axial and forward flights cases. Present scheme with trim routine can predict airloads and inflow distribution of forward flight with good accuracy. Then, the transition flight condition is calculated. The rotor used in this wake calculation is a small-scale AH-1G model. By using a tip-vortex trajectory tracking method, the tip-vortex pairing process are clearly observed in transient flight($\mu$=0.03) and disappears at a slightly higher advance ratio($\mu$=0.05). According to the steady flight simulation at $\mu$=0.03, it is confirmed the tip-vortex pairing process is continued in the rear part of rotor disk and not occurs in the front part. Time averaged inflow in this case is predicted as smooth distribution.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.2
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• pp.173-180
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• 2015

North Korea has developed ballistic missiles over the past 30 years. It is believed that they have a variety of ballistic missiles more than 1,000. Because these ballistic missiles threaten South Korea directly, accurate analysis of them is essential. Flight trajectories of the ballistic missiles are generally changed by means of adjusting payload weight, Isp, flight path angle, and cut-off time. The flight path angle is widely used to control the missile range. However it is difficult to predict the missile trajectory exactly in real operational environment because the missile could be launched according to its intention and purpose. This work analyzed the 1,000 km range MRBM's trajectory characteristics from adjusting flight path angle which is depressed as well as lofted method. The analysis of missile trajectory characteristics is based on the simulation of the missile trajectory model developed by KNDU research team.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.4
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• pp.614-623
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• 2015

When the speed of a coaxial rotor helicopter in forward flight increases, the wake skew angle of the rotor increases and consequently the position of the vena contracta of the upper rotor with respect to the lower rotor changes. Considering ambient air and the effect of the upper rotor, this study proposes a nonuniform inflow model for the lower rotor of a coaxial rotor helicopter in forward flight. The total required power of the coaxial rotor system was compared against Dingeldein's experimental data, and the results of the proposed model were well matched. A plant model was also developed from first principles for flight simulation, unknown parameter estimation and control analysis. The coaxial rotor helicopter used for this study was manufactured for surveillance and reconnaissance and does not have any stabilizer bar. Therefore, a feedback controller was included during flight test and parameter estimation to overcome unstable situations. Predicted responses of parameter estimation and validation show good agreement with experimental data. Therefore, the methodology described in this paper can be used to develop numerical plant model, study non-uniform inflow model, conduct performance analysis and parameter estimation of coaxial rotor as well as other rotorcrafts in forward flight.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.177-182
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• 2003

In this study, a performance model of the Smart UAV propulsion system with ducts, tip jets and variable main nozzle, which has flight capability of the rotary wing mode for the take-off/landing and low speed forward flight as welt as the fixed wing mode for high speed forward flight, has been newly developed. With the proposed model, steady-state performance analysis was performed at various flight modes and conditions, such as rotary wing mode, fixed wing mode, compound wing, mode altitude and flight speed. In investigation of performance analysis, it was noted that the operational capability of the propulsion system was limited due to the duct losses depending on each flight mode, and the limitation with the altitude variation case has much greater than that with the flight speed variation case.