• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.499-505
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• 2004

A Propulsion System of the CRW(Canard Rotor Wing) type UAV(Unmanned Aerial Vehicle) was composed of the turbojet engine to generate the propulsive exhaust gas, and the duct system including straight bent ducts, tip-jet nozzles, a master valve and a variable main nozzle for three flight modes such as lift/landing mode, low speed transition flight mode and high speed forward flight mode. In this study, in order to operate safely the propulsion system, the dynamic Performance behavior of the system was modeled and simulated using the SIMULIN $K^{ }$, which is the user-friendly GUI type dynamic analysis tool provided by MATLA $B^{ }$. In the transient performance model, the inter-component volume model was used. The performance analysis using the developed models was performed at various flight condition, valve angle positions and fuel flow schedules, and these results could set the safe flight mode transition region to satisfy the inlet temperature overshoot limitation as well as the compressor surge margin. Performance analysis results using the SIMULIN $K^{ }$ performance program were compared with them using the commercial program GSP.m GSP.

• 한국군사과학기술학회지
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• 제12권2호
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• pp.213-221
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• 2009

An aircraft collision accident is a disaster that causes great losses of inventories and lives. Though a collision avoidance warning function is provided automatically to pilots in the aircrafts by the enhancement of the aircraft capability, achieving fast decision-making to escape a collision situation is a complex and dangerous work for pilots. If an in-flight collision situation is controlled by the air traffic control system which monitors all airplanes in the air, it would be more efficient to prevent in-flight collisions because it can handle the emergency before the pilot's action. In this paper, we develop the collision avoidance warning function in the air traffic control system. Specifically, we design and implement the five stages of the collision avoidance function, and propose a visualization method which could effectively provide the operators with the trajectories and altitudes of the aircrafts in a collision situation. By developing an in-flight collision warning function in the air traffic control system that visualizes flight patterns through the state transition data of in-flight aircrafts on the flight path lines, it can effectively prevent in-flight collisions with traffic alerts. The developed function allows operators to effectively select and control the aircraft in a collision situation by providing the operators with the expected collision time, the relative distance, and the relative altitude while assessing the level of alert, and visualizing the alert information which includes the Attention-Warning-Alert phase via embodying the TCAS standard. With the developed function the air traffic control system could sense an in-flight collision situation before the pilot's decision-making moment.

• 한국항공운항학회지
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• 제13권2호
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• pp.14-26
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• 2005

A tilt-rotor aircraft has various flight modes : helicopter, airplane, and conversion. Each of flight mode has unique and nonlinear flight characteristics. Therefore the gain schedules for whole flight envelope are required for effective flight performance. This paper proposes collective, flap, and nacelle angle scheduler for whole flight envelope of the Smart UAV(Unmanned Air Vehicle) based on CAMRAD(Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics) II analysis results. The scheduler designs are improved so that the pitch attitude angle of helicopter mode was minimized. The range of scheduler are reduced inside of engine performance limits. The conversion corridor and rotor governor are suggested also.

• 항공우주시스템공학회지
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• 제18권1호
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• pp.29-36
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• 2024

최근 도심항공모빌리티(Urban Air Moility, UAM)의 개념이 미래항공모빌리티(Advanced Air Mobility, AAM)으로 확장되면서 틸트로터형 수직 이착륙기에 관한 연구개발이 활발하다. 틸트로터의 경우 수직비행과 수평비행 사이에 천이비행을 하게 되는데 천이비행 구간의 비행 안정성을 확보하기 위해 블레이드 피치각 제어시스템을 활용할 수 있다. 또한 개별 블레이드 제어(Individual Blade Control, IBC)를 통하여 천이비행 구간 동안 발생하는 소음 및 진동을 감소시킬 수 있다. 본 논문에서는 전기-기계식 구동기 기반 블레이드 피치각 제어시스템의 개별 블레이드 제어를 위한 외란 관측기와 시간 지연제어기를 설계하고 수치 시뮬레이션을 통해 설계한 제어기들의 성능을 비교분석한다.

• 시스템엔지니어링학술지
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• 제1권2호
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• pp.43-48
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• 2005

This paper describes the results of applying States and Modes Analysis, one of the requirements analysis techniques, to the development requirements of flight control software for Smart UAV. State/mode table enabled us to investigate various operation and design concepts, and as a result essential requirements for flight control software were established without omitting necessary requirements. Through the use of scenario-specific state transition diagrams, dynamic behaviours and control/response interfaces between each state and mode could been clearly identified, which made it possible to establish requirements related to dynamic behaviours of states and modes which are essential to the design of flight control software.

• 디지털정책학회지
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• 제1권2호
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• pp.47-52
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• 2022

드론 비행의 위치 인식에 있어 GPS 신호의 절대적 의존성, 비행 안정성, 배터리 한계로 인한 비행시간 문제는 드론 산업 발전의 큰 제약이 되고 있다. 특히 20분 내외의 짧은 임무 비행시간은 드론 활용에 있어 큰 걸림돌이 되고 있으며, 이를 극복하기 위해 액체수소를 에너지원으로 이용한 드론개발이 활발히 진행되고 있다. 하지만 액체수소 드론개발의 속도보다 현재의 규제 및 인증 제도 개정의 속도가 더뎌 개발 드론의 시험, 인증, 상용화에 어려움을 겪고 있으며, 이는 결국 드론 시장 선점의 문제점이 되고 있다. 본 논문에서는 수소 에너지 기반 드론개발 동향을 분석하며 규제와 인증 제도의 한계점을 소개하고 해결방안을 간략히 제시한다.

• 천문학회지
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• 제29권spc1호
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• pp.339-340
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• 1996

In the present study we examine physical characteristics of a thin and rigid magnetic flux tube with a steady flow inside, which is embedded vertically upward in the solar atmosphere. We found from this study that (1) The downward material flow gives rise to a dominant heating in the flux tube which works with the conductive heating in the same direction. However, the upflow flow creates a dominant cooling which works against the conductive heating, resulting in a steeper temperature gradient with a shallower transition region. (2) Since the thickness of the transition region determines the material content in the transition region, a broader transition region of the downflow tube produces a larger differential measure.

• 천문학회보
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• 제22권
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• pp.36.2-37
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• 1997

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1770-1771
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• 2011

In mission planning of UAV applications, especially for the missions requiring height transitions, it is required to generate reference flight trajectories considering the performances of the engine installed in the UAV. Even though the vertical line following guidance based height transition trajectory generation method has been developed to build reference height transition trajectories easily, it is not adequate for considering engine performances effectively since many engine characteristics and performances have conventionally been described in the V-H(speed-height) plane which is not the very space where the UAVs are actually flying. In this paper, we derive the trajectories in V-H plane for the vertical line following flights. And based on the results, a new algorithm to design the reference height transition trajectories for UAV applicaions. Simulation results demonstrate that the proposed algorithm is very effective and easily applicable.

• 항공우주시스템공학회지
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• 제2권3호
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• pp.1-6
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• 2008

The tilt rotor aircraft has the flight characteristics which takes off vertically like a helicopter and flies forward like an airplane. Especially, the transition process from a helicopter to an airplane mode requires not only the mixing of control inputs but also the stability and controllability augmentation system(SCAS) in order to keep the safe flight because there are compound flight dynamic characteristics of a helicopter and an airplane including non-linearity, uncertainty. This paper describes the design of SCAS in a lateral motion for the tilt rotor aircraft based on the $H_{\infty}$ control method, which was performed from mathematical model with weighting matrix based on the relationship between the $H_{\infty}$ norm and the sensitivity function. Through simulation analysis for the controller designed on the $H_{\infty}$ control theory, it was shown that this method may be applied to the control design of the tilt rotor aircraft.