• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.46 no.11
• /
• pp.902-910
• /
• 2018

This paper deals with spacecraft intercept problem on non-coplanar elliptical obit considering J2 perturbation. This disturbance addressed in this work is a major factor changing the trajectory of a spacecraft orbiting the Earth. To resolve this issue, a real-time intercept method is proposed. This method is based on the optimization problem which consist of the equation of motion considering spherical earth and impulse, and the optimal solution numerically obtained is set as the direction of the thrust of the interceptor. The position error is resolved by iteratively solving the optimization problem and modifying the direction of thrust of interceptor. The proposed method in this paper is verified by using various numerical examples.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.9
• /
• pp.859-866
• /
• 2008

A guidance scheme for controlling the relative geometry of multiple flight vehicle formation flying is proposed. Each flight vehicle in the formation takes the roles of leader and follower simultaneously except for the formation leader. In this scheme, the flight commands for a leader are shared by all the followers and this leaders to a synchronized flight of all flight vehicles comprising the formation. Lyapunov stability theorem is used to obtain the guidance law. High fidelity nonlinear simulation results are presented to show the effectiveness of the proposed guidance law using a reconnaissance and surveillance mission example.

• Journal of the KSME
• /
• v.32 no.9
• /
• pp.788-796
• /
• 1992

이 글에서는 극초음속 항공우주 비행기의 개요 및 개발배경, 구조기능 및 추진체계, 그리고 개발 및 설계의 제반고려사항 등에 관하여 알아보았다. 단단계형 공기흡입식 추진체계라는 새로운 개념의 도입은 미래 극초음속 비행체의 재활전용성과 항공 및 우주의 운항 용이성이라는 두 가 지의 가능성을 제시한다는 점에서 큰 의미를 갖고 있다. 극초음속 항공우주비행기의 실현가능 성은 공기흡입식 추진체계의 핵심부분인 스크램제트엔진 개발의 성공여부에 달려 있다고 하겠다. 이러한 스크램제트엔진에 관한 연구 및 개발은 현재 진행중이며, 오늘날 첨단 추진체 연구분야 중의 하나로 여겨지고 있다.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.11
• /
• pp.1072-1078
• /
• 2008

An adaptive control algorithm for spacecraft rendezvous and docking in a Keplerian orbit is presented. The equations of relative motion of two spacecrafts expressed in a local-vertical-local-horizontal rectangular frame are converted to a general Hamiltonian form, then an adaptive control method developed for the uncertain Hamiltonian system is applied to the rendezvous and docking problem. A smooth projection algorithm is applied to keep the parameter estimates inside a singularity-free region, and a numerical example shows that the developed controller successfully deals with the unknown mass of the chaser spacecraft.

• Journal of Aerospace System Engineering
• /
• v.15 no.1
• /
• pp.72-79
• /
• 2021

In this study, as part of the development of an autonomous flying personal aircraft, an equivalent model of the main wing assembly of an Optionally Piloted Personal Air Vehicle (OPPAV) was developed. Reliability of the developed equivalent model was verified by eigenvalue analysis. The main wing assembly consisted of a main wing, an inboard pod, and an outboard pod. First, for developing an equivalent model of each component, components to produce the equivalent model were divided into several sections. Nodes were then created on the axis of the equivalent model at both ends of each section. In addition, static analysis with unit force and unit moment was performed to calculate the deformation or the amount of rotation at the node to be used in the equivalent model. Equivalent axial, bending, and torsional stiffness of each section were calculated by applying the beam theory. Once the equivalent stiffness of each section was calculated, information of a mass and moment of inertia for each section was entered by creating a lumped mass in the center of each section. An equivalent model was developed using beam element. Finally, the reliability of the developed equivalent model was verified by comparison with results of mode analysis of the fine model.

• Journal of Space Technology and Applications
• /
• v.2 no.2
• /
• pp.67-80
• /
• 2022

The missile early-warning satellite systems have been developed and upgraded by some space-developed nations, under the inevitable trend that the space is more strongly considered as another battle field than before. As the key function of such a satellite-based early warning system, the prediction algorithm of the missile flight trajectory is studied in the paper. In particular, the evolution computation, receiving broad attention in the artificial intelligence area, is applied to the proposed prediction method so that the global optimum-like solution is found avoiding disadvantage of the previous non-linear optimization search tools. Moreover, using the prediction simulator of the launch vehicle flight trajectory which is newly developed in C# and Python, the paper verifies the performance and the feature of the proposed algorithm.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.39 no.2
• /
• pp.121-127
• /
• 2011

This paper presents an autonomous formation flight algorithm for micro aerial vehicles (MAVs) and its flight test results. Since MAVs have severe limits on the payload and flight time, formation of MAVs can help alleviate the mission load of each MAV by sharing the tasks or coverage areas. The proposed formation guidance law is designed using nonlinear dynamic inversion method based on 'Leader-Follower' formation geometric relationship. The sensing of other vehicles in a formation is achieved by sharing the vehicles' states using a high-speed radio data link. the designed formation law was simulated with flight data of MAV to verify its robustness against sensor noises. A series of test flights were performed to validate the proposed formation guidance law. The test result shows that the proposed formation flight algorithm with inter-communication is feasible and yields satisfactory results.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.11
• /
• pp.968-973
• /
• 2014

Optionally Piloted Vehicle is one of the UAV development technology and method, which can provide the economic and efficient unmanned system. Existing manned aircraft is evaluated through much flight operations and it can supply the reliable aircraft platform, engine and subsystems for operation. In addition, OPV can be operated both manned and unmanned vehicle to satisfy the mission requirement. under the certain flight conditions. This paper describes main development procedures for automatic flight control system of OPV and summarizes the technical issues and results.

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

• Aerospace Industry
• /
• s.93
• /
• pp.16-19
• /
• 2006

로봇항공기란 "무인항공기(Unmanned Aerial Vehicle : UAV)"의 별칭으로 조종사 없이 비행체 스스로 정찰, 감시, 공격 등의 임무를 수행하는 첨단과학의 결집체이다. 우리나라 무인항공기 분야 인재들의 경연을 통해 국내 무인항공기 기초기술 역량을 가늠해 볼 수 있는 "제5회 한국 로봇항공기 경연대회"가 지난 산업자원부 주최로 지난 10월 14일 한국항공대학교에서 성황리에 개최되었다.