• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.1
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• pp.111-116
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• 2010

To improve occupants' safety in an emergency, crashworthy design is necessary to rotorcraft design and development. Especially, landing gear has the important role for crashworthy design because landing gear absorbs relatively large energy for the crash landing. In addition, military specifications require failure of landing gear shall not increase danger to any occupants by penetration of the airframe. To meet the specification requirements, crashworthiness device like failure mechanism should be prepared so that landing gear is collapsed safely and doesn't penetrate the airframe. In this study, design and design development test of the failure mechanism which is necessary for the rotorcraft landing gear was performed. First, collapse scenario was determined for the landing gear not to penetrate the airframe. Then, the failure pin which is the most important part of the failure mechanism was designed with 2 strength range in order to meet design criteria. Finally, design of the failure mechanism was verified successfully by design development test.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.15-20
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• 2005

Most of studies for the ground load and ground behavior of landing gear have been conducted with an assumption that the structure of landing gear was rigid body. The assumption of rigid body during design process results in many errors or discrepancy. High ground load occurs in 3 directions on the shock absorbing strut during landing. This ground load initiated high structural deformation. In this study, the flex-multi-body dynamics is applied to adapt flexible bodies, so the results of analysis can be described close to landing gears real behaviour.

• Korean Journal of Applied Biomechanics
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• v.24 no.1
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• pp.59-66
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• 2014

The purpose of this study was to investigate the effects of knee joint muscle fatigue and overweight on shock absorption during single-leg landing of adult women. Written informed consent forms, which were approved by the human subject research and review committee at Dong-A University, were provided to all subjects. The subjects who participated in this study were divided into 2 groups: a normal weight group and an overweight group, consisting of 15 young women each. Both the normal weight group and the overweight group showed that use soft landing and ankle dominant strategy. The peak vertical ground reaction force, the knee joint absorption power, and eccentric work done, as the increase of knee joint muscle fatigue level, showed a decrease. And the hip joint absorption power and eccentric work done, as the increase of weight, was less than the overweight group showed the normal weight group. In conclusion, the accumulation of the knee joint muscle fatigue and the increase of body weight may lead to an increased risk of injury during landing.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.333-336
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• 2003

For long time, the takeoff and landing control of airship was worked by human handling. With the development of the autonomous control system, the exact controls during the takeoff and landing were required and lots of methods and algorithms were suggested. This paper presents the result of airship take-off and landing by buoyancy control using air ballonet volume change and performance control of pitch angle for stable flight within the desired altitude. For the complexity of airship's dynamics, firstly, simple PID controller was applied. Due to the various atmospheric conditions, this controller didn’t give satisfactory results. Therefore, new control method was designed to reduce rapidly the error between designed trajectory and actual trajectory by learning algorithm using an artificial neural network. Generally, ANN has various weaknesses such as large training time, selection of neuron and hidden layer numbers required to deal with complex problem. To overcome these drawbacks, in this paper, the RBFN (radial basis function network) controller developed.

• Physical Therapy Korea
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• v.11 no.4
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• pp.1-6
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• 2004

The kinematics involved in different landing strategies may be related to the occurrence of trauma. Several sources suggest that the angle of knee extension on touchdown and impact with the ground determines the magnitude of the impact force and, indirectly, knee loading. This study compared the initial knee angle and maximum knee flexion angle at the instant of impact on drop-landings between healthy men and women. In this study, 60 participants (30 males, 30 females) dropped from a height of 43 cm. A digital camera and video motion analysis software were used to analyze the kinematic data. When landing, there was significant difference between the two groups ($15.67{\pm}6.05^{\circ}$ in male, $24.10{\pm}6.34^{\circ}$ in female) in the mean knee flexion angle. The range of knee flexion on landing ($44.06{\pm}10.97^{\circ}$ in male, $36.96{\pm}9.99^{\circ}$ in female) also differed significantly (p<.05). The greater knee flexion that was observed in the male subjects would be expected to decrease their risk of injury. Women land with smaller range of knee flexion than men and this might increase the likelihood of a knee injury.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.5
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• pp.788-797
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• 2011

This paper analyzes the accuracy on the approach and landing of aircraft to an airport through comparison with airbase Precision Approach Radar and aircraft track data of DGPS equipped in aircraft. The proposed analysis result could be a basis for verifying the possibility that DGPS can be utilized in Airbase precision approach and landing. Position identification capability of widely used commercial DGPS is fairly accurate on latitude and longitude, while there is a slight error for being used in an airbase accurate approach and landing of Category I precision when it comes to altitude. Thus, we tested accuracy by analyzing actual flight track data of high performance aircraft to verify the accuracy of the airbase approach and landing using DGPS. Through the research, we developed instrumentation to compare PAR track data with DGPS track data, which can be used in reducing the number of PAR verification Flight utilizing it as a system measuring PAR accuracy at PAR installation phase.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.1
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• pp.99-104
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• 2009

In this paper, the drop characteristic of the small aircraft landing gear of SUAV has been analyzed and performed on orifice optimal design for shock absorption efficiency. The SUAV landing gear was simple oleo pneumatic type without metering pin. The landing gear was modelled by MSC ADAMS software. Drop test evaluation was conducted to confirm the analysis model. As a result of correlation between analysis and test results, it was verified that these results were coincided with very well. After confidence review of analysis model through the correlation between test and analysis results, design parametric study was performed by using confirmed analysis model. Optimal orifice size with best efficiency have been decided in this study.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.2
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• pp.150-159
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• 2010

The approach and landing phase of a re-entry vehicle is composed of Steep Glideslope phase, Circular Flare phase, Flare Maneuver phase. The trajectory planning algorithm with geometric parameters is studied in this paper for on-board trajectory planning. This algorithm generate reference trajectory rapidly considering safe landing of re-entry vehicle. In this paper, the Mamdani Fuzzy PD type controller for longitudinal and lateral control is designed which has robustness of nonlinear system. In addition, the simulation is performed including initial downrange and crossrange errors, and the results shows that the proposed fuzzy logic controller has good performance.

• Journal of Aerospace System Engineering
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• v.14 no.2
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• pp.20-27
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• 2020

Several uncertainties in the landing environment of an aircraft are not considered, such as the falling speed, ambient temperature, and sensor noise. These uncertainties negatively affect the performance of the controller applied to a landing gear. The sliding mode control (SMC) method, which maintains the optimal performance of a controller under uncertainties, is used in this study. The landing gear is equipped with a magnetorheological damper that changes the yield shear stress according to the applied magnetic field. The applied controller employs a hybrid control combining Skyhook control and force control. The SMC maintains the optimal performance of the hybrid control by minimizing the tracking error of the damper force, even in various landing environments where parameter uncertainties are applied. The effect of SMC is verified through co-simulation results from Simscape and Simulink.

• Proceedings of the Korea Society for Simulation Conference
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• 2004.05a
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• pp.131-135
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• 2004

Landing gear force reaction module is important for aircraft take off and landing simulation. But usually this modulo is not accounted for control law design simulation. because it does not affect the flying quality of aircraft. Now a days, this module is getting more important according to the increase of needs for training purpose simulation and specific control law design such as unmaned aircraft landing on the moving platform. In this paper 1DOF mass spring simple force system per gear was accepted.