• Proceedings of the KSME Conference
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• 2007.05a
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• pp.654-659
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• 2007

In this paper, the fatigue load spectrum for tilt rotor UAV is developed and fatigue analysis is achieved for flaperon joint. Tilt rotor UAV has two modes which are helicopter mode when UAV is taking off and landing and fixed wing mode when UAV is cruising. To make fatigue load spectrum, FELIX for helicopter mode and TWIST for fixed wing mode are used. And Fatigue analysis of flaperon joint is achieved using fatigue load spectrum we obtained. When S-N test data are analyzed, we use the Kriging meta model to get probability S-N curve for whole range of material life. The result which is life of flaperon joint obtained by suggested fatigue analysis procedure in this paper is compared with that obtained by MSC/Fatigue.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.63-67
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• 2000

Up to this day, Most studies of hydroelasticity are inclined to frequency domain atnlysis. Thos amlysis Q the landing, take-4, and dropping of airaqft on a structure. So, the concern of this prrper is a tra a VLFS subjected to dymmic lazd induced by airplane larndirrg and take-off. To predict added mass, dampr exciting force, the source-dipole distribution method were used The responses are accomplished by Fdoimain analysis method is based on Newmark $\beta$ method to pursuit time step pnzcedure taking advantage function for hvdrodvnumic effects.

• Aerospace Engineering and Technology
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• v.6 no.1
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• pp.19-28
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• 2007

In this study, a nonlinear 2 degree of freedom mathematical model has been developed for impact analysis of the nose landing gear of a light aircraft which is composed of an wheel & tire, an Oleo-pneumatic shock strut and the castering wheel fork for the differential braking steering, and then the response of impact is computed using a numerical method. The mathematical model of a nose landing gear contains nonlinear characteristics which are an impact load - deflection property of a tire and internally frictional forces between an inner surface of an upper cylinder and a bearing of a lower rod due to side forces like the declined angle of strut, the moment due to an wheel fork, the side drag due to a steering and it is computed using the 4th-order Runge-Kutta method. The comparison process between analytical results and experimental results of the other proven nose landing gear is carried out to verify the mathematical model.

• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.213-220
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• 2013

Korean Lunar Explorer is planned to be launched in the 2020s according to national space development strategy. The Lunar Explorer will be developed as two unmanned light weight models: a lunar orbiter and a lunar lander. The Lunar Explorer's structure should be designed to have light weight due to constraints from launcher as well as to provide structural safety against launch load, in-orbit condition and landing condition and to serve accommodation space for mission equipment. Core technology related to structural development of lunar explorer should be developed in advance. Especially, for lunar lander, technology for developing landing gear which enables lander to land safely on lunar surface is required essentially. This paper deals with structural development of lunar lander ground test model including design, manufacturing and test.

• Korean Journal of Applied Biomechanics
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• v.24 no.4
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• pp.375-383
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• 2014

The purpose of this study was to assess the inter-segmental trunk motion during which multi-segmental movements of the spinal column was designed to interpret the effect of segmentation on the total measured spine motion. Also it analyzed the relative motion at three types of the spine models in drop landing. A secondary goal was to determine the intrinsic algorithmic errors of spine motion and the usefulness of such an approach as a tool to assess spinal motions. College students in the soccer team were selected the ten males with no history of spine symptoms or injuries. Each subject was given a fifteen minute adaptation period of drop landing on the 30cm height box. Inter-segmental spine motion were collected Vicon Motion Capture System (250 Hz) and synchronized with GRF data (1000 Hz). The result shows that Model III has a more increased range of motion (ROM) than Model I and Model II. And the Lagrange energy has significant difference of at E3 and E4 (p<.05). This study can be concluded that there are differences in the three models of algorithm during the phase of load absorption. Especially, Model III shows proper spine motion for the inter-segmental joint motion with the interaction effects using the seven segments. Model III shows more proper observed values about dynamic equilibrium than Model I & Model II. The findings have shown that the dynamic stability strategy of Model III toward multi-directional spinal motion supports for better function of the inter-segmental motor-control than the Model I and Model II.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.6
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• pp.537-546
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• 2010

This research work contributed to a study for the procedure and methodology to assess the fatigue durability for a composite torque link of helicopter landing gear, which was newly developed and fabricated by the resin transfer moulding technique to interchange with metal component. The simulated load spectrum anticipated to be applied to the torque link during its operation life was generated using an advanced method of probabilistic random process, and the fatigue durability was evaluated by the strength degradation approach on the basis of material test data. The full scale fatigue test was also performed and compared with the analysis results.

• Journal of Aerospace System Engineering
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• v.1 no.2
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• pp.27-36
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• 2007

The Damage Tolerant Design is developed to help alleviate structural failure and cracking problems in aerospace structures. Recently, the Damage Tolerant Design is required and recommended for most of aircraft design. In this paper, the damage tolerant design is applied to tilt rotor UAV. First of all, the fatigue load spectrum for the tilt rotor UAV is developed and fatigue analysis is performed for the flaperon joint which has FCL (fatigue critical location). Tilt rotor UAV has two modes: helicopter mode when UAV is taking off and landing; fixed wing mode when the tilt rotor UAV is cruising. To make fatigue load spectrum, FELIX is used for helicopter mode. TWIST is used for fixed wing mode. Fatigue analysis of flaperon joint is performed using fatigue load spectrum. E-N curve approach is used for picking crack initiation point. The LEFM(Linear Elastic Fracture Method) is considered for analyzing crack growth or propagation. Finally, including the crack initiation and propagation, the fatigue life is evaluated. Therefore the Damage Tolerant Design can be done.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1341-1344
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• 2003

Studies on impact damage of composite laminate shells were fewer compared with those on impact behaviors to analyze time-load, displacement-load and impact energy - energy absorption. Up to date the studies were not enough to demonstrate suitability of their results because they were dependent on theories and numerical analyses. In particular, it is a well-known fact that there was a correlation between initial peak load and damage resistance of composite material flat plates imposed with low-speed impact, but studies on composite material shells with curvature were also very few. Actually structures such as wings or moving bodies of airplanes, motor cases and pressure containers of rockets are circular. And as low-speed impact load is imposed for optimal design of take-off and landing, and containers of airplanes, it is very important to analyze evaluation of behaviors and damaged areas. Therefore, in this paper to evaluate the impact characteristics of the CFRP laminate shell according to size of curvature quantitatively, it was to identify energy absorption and impact damage instruments according to change of impact speed.

• Journal of the Korean Society of Safety
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• v.8 no.4
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• pp.213-222
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• 1993

This paper is concerned with automation of tower cranes in view of the robust control of tower crane during take-off, load hoisting, load lowering and landing. The model equation of the tower crane is induced by using Lagrange's equation and it is linearized at equillibrium point. The control is realized by adopting the optimal regulator method. The effectiveness is proved through the experimental results for the oscillation control of cargo rope and the position controls of trolley and boom by the implementation of digital control using 16 bits microcomputer for the designed optimal control law.

• Journal of the Korean Society of Safety
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• v.28 no.3
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• pp.29-32
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• 2013

An aircraft made an emergency landing through the loss of capability controlling steering. A torsion link which is a part of steering apparatus has been adrift from the steering system and the bolt connected to the steering link has fractured. At the same time, the FLIR(Forward Looking Infrared Radar) mounted in front of the steering link has been also damaged. In the early of this investigation, we considered the failure of the FLIR had occurred first, that FLIR hit the steering link and finally the bolt fractured. The fractured section of the bolt has shown a beach mark and a dimple mark as well. The outside of the bolt has shown a large deformation by a heavy load. As a result, we have found out what the cause of the heavy load and the fractures for bolt, link and FLIR have occurred in what order.