• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.1
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• pp.18-26
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• 2007

The steady-state aerodynamic characteristics of wings on the formation flight were analyzed using the Vortex Lattice Method. When two wings were at formation flight, the sectional lift coefficient of a rear wing was increased due to a front wing. The result showed that the lift drag ratio increased as the rear wing were placed downward and decreased as the lateral spacing between wings increased. The difference of lift drag ratio between forward wing and rear wing increase as the aspect ratio of wings increased. When a rear wings and a forward wings placed at the same height, wings on the formation flight had the maximum lift drag ratio. The results showed that the benefit of the formation flight increased as the number of wings on the formation flight increased.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.8
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• pp.681-688
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• 2021

This paper considers the trajectory and impact point dispersion analysis of the test launch vehicle (TLV). The analysis, which performed before and after its flight test on November 28, 2018, is described and verified by comparing with the flight test results. The six degree-offreedom (DOF) simulation is used to compute the dispersion of the trajectory, attitude, and impact point, where the launch vehicle performance variations and wind effects during the atmospheric phase are included. The impact area to guarantee the flight safety is determined using the results of the dispersion analysis. The flight test results confirm that the safe flight of TLV is performed within the predicted dispersion boundary.

• Journal of Aerospace System Engineering
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• v.14 no.1
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• pp.68-73
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• 2020

This purpose of this paper was to review the development trend of the VTOL MAVs with a ducted propellant that can fly like the VTOL at intermediate and high speeds, hovering, landing, and lifting off vertically over urban areas, warships, bridges, and mountainous terrains. The MAV differs in flight characteristics from helicopters and fixed wings in many respects. In addition to enhancing thrust, the duct protects personnel from accidental contact with the spinning rotor. The purpose of the U.S. Army FCS and DARPA's OAV program is spurring development of a the VTOL ducted MAV. Today's MAVs are equipped with video/infrared cameras to hover-and-stare at enemies hidden behind forests and hills for approximately one hour surveillance and reconnaissance. Class-I is a VTOL ducted MAV developed in size and weight that individual soldiers can store in their backpacks. Class-II is the development of an organic VTOL ducted fan MAV with twice the operating time and a wider range of flight than Class-I. MAVs will need to develop to perch-and-stare technology for lengthy operation on the current hover-and-stare. The near future OAV's concept is to expand its mission capability and efficiency with a joint operation that automatically lifts-off, lands, refuels, and recharges on the vehicle's landing pad while the manned-unmanned ground vehicle is in operation. A ducted MAV needs the development of highly accurate relative position technology using low cost and small GPS for automatic lift-off and landing on the landing pad. There is also a need to develop a common command and control architecture that enables the cooperative operation of organisms between a VTOL ducted MAV and a manned-unmanned ground vehicle.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.7
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• pp.51-60
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• 2002

The Monte-Carlo simulation of statistical analysis is used to investigate the final conditions of states as well as the footprint boundaries resulting from the atmospheric re-entry dispersions. The re-entry dispersions in this paper are specified by a $7\times7$ covariance matrix of latitude, longitude, altitude, bank angle, flight path angle, heading error, and range at entry velocity. The error sources that affect these at re-entry for a deboost are the uncertainties associated with atmospheric density and temperature, initial errors, wind, and estimation error of aerodynamic coefficients. Using $3{\sigma}_n$ deviations of these errors and a nominal flight trajectory, the covariance matrix of state variables can be determined by performing a trajectory error analysis. Major considerations in the application of the Monte-Carlo method are the simulation of perturbed trajectories, bank reversal, and determination of the impact points for each of these trajectories. This paper analyzes the results of uncertainties from the viewpoint of aero-coefficients and bank reversal.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.361-364
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• 1997

The re-enty guidance design involves trajectory optimization, generation of a reference drag acceleration profile with the satisfaction of trajectory constraints. This reference drag acceleration profile can be considered as the reference trajectory. This paper proposes the atmospheric re-entry system which is composed of longitudinal, later and range control. This paper shows the a performance of a re-entry guidance and control system using feedback linearization control and predictive control.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.2
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• pp.90-95
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• 2006

For single engine application like T-50, advanced supersonic jet trainer, airstart capability is very important. This paper presents the results of airstart tests performed to verify T-50 airstart capability for various flight condition. The tests include spooldown, APU assisted and auto-relight airstart tests. Except for the auto-relight tests T-50 engine was successfully restarted for all airstart tests. After modifying FADEC flameout detection schedule, auto-relight tests also were successfully demonstrated. Through T-50 engine airstart tests excellent T-50 airstart capability was validated.

• Aerospace Industry
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• v.50
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• pp.23-27
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• 1997

쌍발복합재 항공기가 지는 3월 29일 마침내 땅을 박차고 올랐다. 지난 93년부터 개발이 시작된 쌍발복합재 항공기는 국내최초로 전 기체구조물을 복합재로 제작되었으며 개발과정에서 많은 시행착오와 시련을 겪기도 하였으나 마침내 처녀비행에 성공한 것이다. 본 고에서는 그동안의 개발과정과 의의를 개발실무자로부터 들어보기로 한다.

• Defense and Technology
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• no.4 s.230
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• pp.22-29
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• 1998

현재 개발이 완료되고 비행시험이 진행중인 FS-X의 개발기간중 FS-X의 운용요구라면 기존의 미국 전투기인 F-15, F-16 또는 F/A-18을 재설계하거나 개조하면 충분히 만족할 수 있고 적은 비용으로 획득할 수 있다는 미국의 주장에 대항한 일본의 대응책과 기술개발력 육성의 문제를 일본의 안전보장이라는 관점에서 정리함으로써 향후 한국의 항공산업 발전에 참고가 되었으면 한다

• Defense and Technology
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• no.5 s.231
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• pp.26-33
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• 1998

현재 개발이 완료되고 비행시험이 진행중인 FS-X의 개발기간중, FS-X의 운용요구라면 기존의 미국 전투기인 F-15, F-16 또는 F/A-18을 재설계하거나 개조하면 충분히 만족할 수 있고 적은 비용으로 획득할 수 있다는 미국의 주장에 대항한 일본의 대응책과 기술개발력 육성의 문제를 일본의 안전보장이라는 관점에서 정리함으로써 향후 한국의 항공산업 발전에 참고가 되었으면 한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.8
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• pp.54-63
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• 2004

The inner surface temperatures of the KSR-III Sounding Rocket launched at 29th November 2002 were measured in the flight test, and the aerodynamic heating rate and outer surface temperature were calculated. The used program is the MINIVER code, which calculate the boundary layer equation based on the theoretical analysis, and its calculation is simulated on the flight time histories. The analysis considered the inner surface heat transfer with one dimensional solid heat conduction. The results showed that the major interior heat transfer is the radiation heat transfer, and the maximum outer surface temperature due to aerodynamic heating reached to $223^{\circ}C$ at fin and the maximum heating rate is about $133kW/m^2$ at nose cap. The whole analysis proved that the surface temperature remained below the allowable temperature, and the KSR-III thermal design satisfies the thermal environmental conditions.