• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.1
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• pp.12-22
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• 2016

Lidar-based hazard avoidance landing system for lunar lander calculates hazard cost with respect to the desired local landing area in order to identify hazard and designate safe landing point where the cost is minimum basically using slope and roughness of the landing area. In this case, if the parameters are only considered, chosen landing target can be designated near hazard threatening the lander. In order to solve this problem and select optimal safe landing point, hazard cost based on relative distance to hazard should not be considered as well as cost based on terrain parameters. In this paper, the effect of hazard cost based on relative distance to hazard on safe landing performance was analyzed and it was confirmed that landing site designation with two relative distances to hazard results in the best safe landing performance by an experiment using three-dimensional depth camera.

• Journal of KSNVE
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• v.7 no.4
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• pp.605-612
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• 1997

A state feedback controller and an observer have been developed and analyzed for an aircraft's safe landing in the windshear called microburst. The observer estimates the ambient wind field as well as the full-order longitudinal state vector. The controller uses the wind and state estimates for guiding the control inputs for safe landing. For the observer and controller gains, the design methodologies of linear quadratic estimation and linear quadratic regulation have been exploited. Analysis shows that some of the microburst-induced aircraft accidents in the past might have been avoided with the designed autopilot.

• International Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.73-78
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• 2015

According to the characteristic of carrier-based aircraft, the method of solving safe set during arresting landing is discussed in this paper based on optimal control and invariant set theory. The safe sets of carrier aircraft are evaluated in different states on the characteristic of longitudinal augmented system by using the level set method. Then, the influence on the boundary of safe set under various factors is analyzed. At last, the maneuverability envelope protection is established based on the corresponding theory, and the validity of the system is verified through simulation. The results demonstrate preliminarily that: compared with mass and thrust, the elevator is the greatest influence factor for the boundary of safe set; the dynamic trajectory of carrier-based aircraft can be located at the interior of safe set effectively with the maneuverability envelope protection.

• ETRI Journal
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• v.45 no.5
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• pp.746-757
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• 2023

This study presents a novel safe landing algorithm for urban drone deliveries. The rapid advancement of drone technology has given rise to various delivery services for everyday necessities and emergency relief efforts. However, the reliability of drone delivery technology is still insufficient for application in urban environments. The proposed approach uses the "landing angle control" method to allow the drone to land vertically and a rapidly exploring random tree-based collision avoidance algorithm to generate safe and efficient vertical landing paths for drones while avoiding common urban obstacles like trees, street lights, utility poles, and wires; these methods allow for precise and reliable urban drone delivery. We verified the approach within a Gazebo simulation operated through ROS using a six-degree-of-freedom drone model and sensors with similar specifications to actual models. The performance of the algorithms was tested in various scenarios by comparing it with that of stateof-the-art 3D path planning algorithms.

• Journal of the Society of Naval Architects of Korea
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• v.61 no.2
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• pp.125-134
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• 2024

The Safe Operating Envelope (SOE) combined with Short-Take-Off and Vertical Landing (STOVL) performance is an essential consideration of a light aircraft carrier for design of hull shape with excellent seakeeping performance in terms of naval air operations as well as traditional naval ship missions such as Transit and Patrol (TAP), and Replenishment at Sea (RAS) and so on. A variety of procedures are systematically combined to determine SOE considering rather complicated missions associated with operation of aircraft onboard. The evaluation of take-off and landing safety missions onboard should consider wind effect on deck and severer seakeeping indices and standards compared with conventional naval ships. In order to support take-off and landing missions, various support activities of the crews are required. So, additional evaluation is needed for indicators such as MSI(Motion sickness Index) and MII(Motion Induced Interruptions), which are quantitative indicators of work ability that appear as a result of motion response. In this study, a standard procedure is developed including the seaworthiness performance indicators, standards, and evaluation procedures that should be considered during design of STOVL aircraft carrier. Analysis results are discussed in terns of air-wake on deck as well as seakeeping indices associated with design parameter changes in view of conceptual design of a light aircraft carrier.

• Physical Therapy Korea
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• v.28 no.1
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• pp.1-12
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• 2021

While efforts have been made to address fall-related injuries in older adults, the problem is unsolved to date. The purpose of this review is to provide a guideline for fall and injury prevention programs in older adults, based on evidence generated over the past 30 years. Research articles published between 1990 and 2020 have been searched on PubMed, using keywords, including but not limited to, falls, hip fracture, injuries, intervention, older adults, prevention, hip protector, vitamin D, safe landing strategy, and exercise. Total of 98 articles have been found and categorized into five intervention areas: exercise program, hip protector, safe landing strategy, vitamin D intake, and compliant flooring. Furthermore, the articles have been rated based on their study design: class 1, randomized controlled trials; class 2, non-randomized controlled trials; class 3, experimental studies; class 4, all other studies. Exercise programs have shown to decrease the risk of fall, and associated injuries. Hip protectors, safe landing strategy, and vitamin D intake were effective in reducing a risk and incidence of hip fracture during a fall. Furthermore, compliant flooring has also decreased hip fracture risk without affecting balance. An integrated approach combining exercise program, wearing a hip protector, teaching safe landing strategies, scheduled vitamin D intake, and compliant flooring installation, is suggested to address fall-related injuries in older adults.

• Journal of Astronomy and Space Sciences
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• v.29 no.4
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• pp.375-380
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• 2012

It is a crucial matter to select a landing site for landers or rovers in planning the Mars exploration. The landing site must have not only a scientific value as a landing site, but also geographical features to lead a safe landing for Mars probes. In this regard, this study analyzed landing site of Mars probes and rovers in previous studies and discussed the adequacy of the landing site to scientific missions. Moreover, this study also examined domestic studies on the Mars. The frameworks of these studies will guide the selection of exploration sites and a landing site when sending Mars probe to the Mars through our own efforts. Additionally, this paper will be used as the preliminary data for selection of exploration site and a landing site.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.4
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• pp.315-320
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• 2010

To improve not only the basic performance but also the fail-safe performance, power consumption of the main landing gear for helicopters, a semi-active control landing gear using hybrid MR damper, was introduced in this paper. This damper of the configuration to install a permanent magnet in a electromagnet MR damper, was designed by the trade-off study on permanent magnet location and a magnet field analysis. Force control algorithm which keep the sum of air spring force and damping force at a specified value during landing, was used for the controller. The drop simulations using ADAMS Model for this semi-active control landing gear, were done. The improvement of the preceding performances as the result to evaluate the landing performance by the simulations, has been confirmed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1181-1187
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• 2012

For the fatigue design of aircraft landing gear, the safe-life approach is applied. Structural defects such as cracks or detrimental deformations should not occur under the fatigue load spectrum depicting the entire lifetime usage of the aircraft. In the design phase, the fatigue life of the landing gear is estimated analytically by adopting the stress-based approach because the fatigue of aircraft landing gear is generally high-cycle fatigue. This utilizes S-N curves that are factored to produce design curves that account for the scatter and surface finish of the material. In the test and evaluation phases, a fatigue test should be conducted for full-scale landing gear to substantiate the fatigue design requirement in the end. In this study, the procedure for the fatigue test and evaluation of aircraft landing gear is presented with real application cases.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.11
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• pp.1085-1091
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• 2014

This paper presents the guidance and control design for automatic carrier landing of a UAV (Unmanned Aerial Vehicle). Differently from automatic landing on a runway on the ground, the motion of a carrier deck is not fixed and affected by external factors such as ship movement and sea state. For this reason, robust guidance/control law is required for safe shipboard landing by taking the relative geometry between the UAV and the carrier deck into account. In this work, linear quadratic optimal controller and longitudinal/lateral trajectory tracking guidance algorithm are developed based on a linear UAV model. The feasibility of the proposed control scheme and guidance law for the carrier landing are verified via numerical simulations using X-Plane and Matlab/simulink.