• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.16 no.4
• /
• pp.54-62
• /
• 2008

International organizations related to air transport such as ICAO, IATA, ACI are forecasting that the number of passenger will grow about 4.4% annually up to 2015. Therefore, the innovation of given system technology and operation procedure is required in global scale to cope with the increase of air traffic demand. CNS/ATM infrastructure based on satellite is considered to play key role in order to solve the problems due to the dramatic increase of air traffic demand over the world. Free flight concept in the air transport operation has been proved with CNS/ATM infrastructure especially in USA and Europe. Therefore, it is necessary to develop key technologies to overcome technology gap and to secure international competitiveness in Korea. ADS-B is an important issue, and new element technologies should be considered as essential items which were shown in Capstone project. Nowadays, the free flight concept is combined to Air Transport Road Map such as NextGen project in USA, SESAR in Europe. In this process, free flight is included in the concepts such as ATM(Air Traffic Management), aviation security and safety, environmental protection and economy development, wide area weather variable reduction service, information integration and application between the related authorities (civil/military) etc. The purpose of research is to establish mid-term and long-term infrastructure plan and strategy for free flight realization in Korea. The analysis of action target and equipment construction status, phase construction plan of infrastructure has been performed by considering mid-term and long-term free flight plans of USA and Europe.

• Journal of Environmental Science International
• /
• v.26 no.6
• /
• pp.779-788
• /
• 2017

In this study, we analyzed the changes in the echolocation and prey-capture behavior of the horseshoe bat Rhinolophus ferrumequinum from search phase to capture time. The experiment was conducted in an indoor free-flight room fitted with an ultra-high-speed camera. We found that the bats searched for food while hanging from a structure, and capturing was carried out using the flight membrane. In addition, it was confirmed that the mouth and uropatagium were continuously used in tandem during the capturing process. Furthermore, using Constant Frequency (CF), we confirmed that the prey catching method reflected the wing morphology and echolocation pattern of R. ferrumequinum. The echolocation analysis revealed that the pulse duration, pulse interval, peak frequency, start-FM-bandwidth, and CF duration decreased as the search phase approached the terminal phase. Detailed analysis of echolocation pulse showed that the end-FM bandwidth, which increases as it gets nearer to the capture time of prey, was closely related to the accurate grasp of the location of an insect. At the final moment of prey capture, the passive listening that stopped the divergence of the echolocation was identified; this was determined to be the process of minimizing the interruption from the echo of the echolocation call emitted from the bat itself and sound waves emitted from the prey.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.11a
• /
• pp.628-635
• /
• 2010

Properties of bleed air that is air source of ECS(Environmental Control System) can be rapidly changed with airplane engine operating conditions during flight. Therefore, ECS can be operated at a high performance or not during flight. So, high performance ACM has to be developed in order to flight safely. A adaptability of phase changing heat exchanger was esteemed at ACM type ECS in this study. As a result of this study, it is found that ECS outlet temperature can be controlled in a certain range with the phase changing phenomenon.

• Journal of IKEEE
• /
• v.28 no.2
• /
• pp.187-198
• /
• 2024

Estimating the phase boundary in two-phase flow is crucial for designing and optimizing industrial processes. Electrical impedance tomography (EIT) is a promising technique for imaging phase distribution in such flows. This paper proposes using a cuckoo search (CS) optimization algorithm to estimate the phase boundary with EIT. The boundary is parameterized using the Fourier series, and the coefficients are determined by the CS algorithm. The CS algorithm iteratively seeks the phase boundary configuration by minimizing a cost function. Computer simulations and phantom experiments demonstrate the effectiveness of this method in estimating phase boundaries in two-phase flow.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.1864-1866
• /
• 1997

Uncertainties in the aerodynamic coefficients or time delay effects in implementing an autopilot algorithm can make a Flight Control System(FCS) unstable. When a FCS enters unstable state, the actuator or sensor limiters in FCS make the unstable system not diverge but be in the state of stable limit cycle. If an autopilot recognize the FCS to be in the stable limit cycle phenomenon, it woudl be better to adjust autopilot gains to stabilize the FCS. A novel method to stabilize a FCS using parameter estimation and maintenance of given phase margin is proposed. The method is applied to roll control loop and verified its performance.

• Journal of Astronomy and Space Sciences
• /
• v.36 no.4
• /
• pp.293-306
• /
• 2019

In this study, the observational arc-length effect on orbit determination (OD) for the Korea Pathfinder Lunar Orbiter (KPLO) in the Earth-Moon Transfer phase was investigated. For the OD, we employed a sequential estimation using the extended Kalman filter and a fixed-point smoother. The mission periods, comprised between the perigee maneuvers (PM) and the lunar orbit insertion (LOI) maneuver in a 3.5 phasing loop of the KPLO, was the primary target. The total period was divided into three phases: launch-PM1, PM1-PM3, and PM3-LOI. The Doppler and range data obtained from three tracking stations [included in the deep space network (DSN) and Korea Deep Space Antenna (KDSA)] were utilized for the OD. Six arc-length cases (24 hrs, 48 hrs, 60 hrs, 3 days, 4 days, and 5 days) were considered for the arc-length effect investigation. In order to evaluate the OD accuracy, we analyzed the position uncertainties, the precision of orbit overlaps, and the position differences between true and estimated trajectories. The maximum performance of 3-day OD approach was observed in the case of stable flight dynamics operations and robust navigation capability. This study provides a guideline for the flight dynamics operations of the KPLO in the trans-lunar phase.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.27 no.2
• /
• pp.285-293
• /
• 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 Korean Society for Aeronautical & Space Sciences
• /
• v.37 no.4
• /
• pp.350-358
• /
• 2009

This paper describes a result of the guidance and control for re-entry vehicle during TAEM phase. TAEM phase (Terminal Aerial Energy Management phase) has many conditions, such as density, velocity, and so on. Under these conditions, we have optimized trajectory and other states for guidance in TAEM phase. The optimized states consist of 7 variables, down-range, cross range, altitude, velocity, flight path angle, vehicle's azimuth and flight range. We obtained the optimized reference trajectory by DIDO tool, and used feedback linearization with neural network for control re-entry vehicle. By back propagation algorithm, vehicle dynamics is approximated to real one. New command can be decided using the approximated dynamics, delayed command input and plant output, NARMA-L2. The result by this control law shows a good performance of tracking onto the reference trajectory.

• International Journal of Aeronautical and Space Sciences
• /
• v.12 no.2
• /
• pp.190-199
• /
• 2011

Unsteady flow simulations of complete helicopter configurations were conducted, and the flow fields and the aerodynamic interferences between the main rotor, fuselage, and tail rotor were investigated. For these simulations, a three-dimensional flow solver based on unstructured meshes was used, coupled with an overset mesh technique to handle relative motion among those components. To validate the flow solver, calculations were made for a UH-60A complete helicopter configuration at high-speed and low-speed forward flight conditions, and the unsteady airloads on the main rotor blade were compared to available flight test data and other calculated results. The results showed that the fuselage changed the rotor inflow distribution in the main rotor blade airloads. Such unsteady vibratory airloads were produced on the fuselage, which were nearly in-phase with the blade passage over the fuselage. The flow solver was then applied to the simulation of a generic complete helicopter configuration at various flight conditions, and the results were compared with those of the CAMRAD-II comprehensive analysis code. It was found that the main rotor blades strongly interact with a pair of disk-vortices at the outer edge of the rotor disk plane, which leads to high pulse airloads on the blade, and these airloads behave differently depending on the specific flight condition.

• Aerospace Engineering and Technology
• /
• v.12 no.1
• /
• pp.189-199
• /
• 2013

This paper summarizes results of second stage attitude control of KSLV-I third flight test. The results show that three axes attitude control at coasting phases of KSLV-I was successfully accomplished by the reaction control system, and pitch and yaw attitude control at thrusting phase where second stage kick motor burns was also normally accomplished by using the thrust vector control system. It is verified that the second stage controller performed successfully for all flight phases regardless of some disturbances due to mass center offset, slag effects, and residual thrust of kick motor. These results may provide an important basis in enhancing domestic technology level of attitude control of launch vehicle.