• Journal of Engineering Education Research
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• v.15 no.2
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• pp.52-57
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• 2012

This study summarized the case study of a course development of introductory engineering design considering the characteristics of civil and environmental engineering. The course mainly depends on conducting the design projects. The self-developed text book for the course consists of learning and activities of the core elements for the creation and decision of ideas and two independent design projects. Especially, the design project drew from a survey of students majoring in civil and environmental engineering and is well knitted to help students obtain the potential for soft-landing at higher major courses.

• 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.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.5-16
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• 2008

Field monitoring data of nine sites were investigated to suggest an evaluation method on lateral movement of the quaywall on soft grounds. It was found that in order to evaluate the lateral movement of quaywalls with foundation piles such as the landing pier, the safety factor of slope should be applied with consideration of the stabilizing effect of the piles. If the required safety factor of slope is greater than 1.6 in slope stability analysis with consideration of the stabilizing effect of the piles, the quaywalls are considered to be safe against lateral movement. On the other hand, for the gravity-type quaywalls such as the caisson type quaywall, the required safety factor of slope should be greater than 1.3.

• Current Industrial and Technological Trends in Aerospace
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• v.9 no.1
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• pp.119-129
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• 2011

The soft landing of a lunar lander after the entrance of lunar orbit is an essential prerequisite for the accomplishment of the lander's lunar mission. During the landing process of a lunar lander, efficient shock absorption and stability maintenance are indispensible technology to protect payloads. Therefore, the landing gear is a crucial structural component of a lunar lander, it has to absorb the kinetic energy associated with touchdown and support the static load of the landing module in an upright position. In this paper, various landing gears of lunar landers which are being developed as well as which had been successfully landed on the moon surface are investigated. In the end, the Korean lunar lander, which is being designed for preliminary development model, is presented as an example of the lunar lander development.

• International Journal of Automotive Technology
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• v.8 no.4
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• pp.429-436
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• 2007

In this study, we improved control performance of an EMV (electromechanical valve) system using a PM/EM (permanent magnet/electromagnet) hybrid EMA (electromagnetic actuator) and showed the feasibilities of both soft landing and fast transition of the EMV system using a simple PID control. The conventional EMV systems using only EM show significant nonlinear characteristics. Therefore, it is very difficult to control the valve position and several complex control schemes are used. This paper focused on the control performance improvement using a PM/EM hybrid actuator. In particular, a PM is used as a key design parameter such as a bias current of a magnetic bearing in order to improve the linear characteristic of the actuator, although most PM/EM hybrid actuators use a PM as a power saver during valve-open and -closed states. First, a FE (finite element) analysis was performed to confirm its linear static force characteristics. Then, both a test rig and a valve control system were built in order to prove experimentally the control performance improvement of the actuator. Finally, feasibilities of both soft landing and fast transition of the system were shown experimentally through gain-scheduled PID (proportional derivative integral) control.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.12
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• pp.1037-1044
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• 2014

In this study, we designed a drop test system considering lunar surface environment and tested landing gear of experimental lunar lander. The lunar lander would be landed at soil place for soft landing. When the lunar lander touches down, the acceleration of the lander is largely affected by mechanical characteristics of the lunar soil. Accordingly, a drop test using lunar soil is needed to verify the performance of the lunar landing gear. Because the lunar soil is not available generally, we developed a lunar simulant KAUMLS(Korea Aerospace University Mechanical Luna Simulant) based on mechanical properties of the lunar soil of NASA's LUNA PROJECT. In addition, drop tests on steel plate and dry sand are performed to evaluate impact characteristics by the surface environment.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.167.2-167
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• 2001

This paper presents guidance and control laws which guarantee a minimum fuel consumption and have obustness against various disturbances during a terminal-landing phase on the lunar surface. The nonlinear robust tracking control system is designed to track the reference profiles, which are expressed by exponential functions. An adjustment law in the tracking controller is given in the form of the differential equations with respect to the controller´s variable gains. Computer simulations are performed to examine the tracking accuracy, the robustness in a thrust failure mode, and the vertical soft landing at a pre-assigned point on the lunar surface. The results of numerical simulation show the effectiveness of the present control law.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.2
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• pp.99-107
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• 2022

Urban Air Mobility (UAM) such as a drone taxi is one of the future transportations that have recently been attracting attention. Along with the construction of an urban terminal, an accurate landing system for UAM is also essential. However, in urban environments, reliable Global Navigation Satellite Systems (GNSS) signals cannot be received due to obstacles such as high-rise buildings which causes multipath and non-line of sight signal. Thus, the positioning result in urban environments from the GNSS signal is unreliable. Consequently, we propose the Ultra-Wideband (UWB) network to assist the soft landing of UAM on a vertiport. Since the positioning performance of UWB network depends on the layout of UWB anchors, it is necessary to optimize the layout of UWB anchors. In this paper, we propose a two-steps genetic algorithm that consists of binary genetic algorithm involved multi objectives fitness function and integer genetic algorithm involved robust solution searching fitness function in order to optimize taking into account Fresnel hole effects.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.8
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• pp.1250-1258
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• 1997

This paper reports on the development of a new foot for a quadrupedal jointed-leg type walking robot. The foot has 2 toes, one at the front and the other at the rear side, for stable landing on uneven ground by point contact. The toes can move up and down independantly, guided by double-wishbone shaped parallel links which enable the lower leg to rotate with respect to a remote center on the ground surface. The motion of each toe is damped by a hydropneumatic shock absorber integrated in the foot in order to absorb the dynamic landing shock. Furthermore, the new foot can reduce the maximum hip joint drive torque by shortening the moment arm length between the hip joint and the landing force vector on the ground. Intensive experiments were carried out in this study by using a one-leg walking model to investigate the soft landing performance of the foot which could be hardly offered by conventional robot feet such as a flat plate with a gimbal type ankle joint. And it was confirmed that the hip joint torque of the leg walking on the flat surface could be reduced remarkably by using the new foot.

• Journal of Convergence for Information Technology
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• v.12 no.2
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• pp.37-46
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• 2022

The purpose of this study is to provide basic data onto preparing soft landing plan of future education policy by exploring direction of future education for the common good using big data and keyword network analysis. Based on the big data provided by Textom, data was collected under the keyword 'future education + common Good' and then keyword network analysis was performed. As a result of the research, it was found that 'common good', 'social', 'KAIST future warning', 'measures', 'research', 'future education', 'politics' were common keywords in the social awareness of future education for the common good. The results of this study suggest that the social awareness of future education for the common good is related to factors related to human, physical environment, social response, academic interest, education policy, education plan, and related variables, It was closely related. Based on these results, we suggested implications for the support for the preparation of a soft landing plan of future education for the common good.