• 한국항행학회논문지
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• 제25권6호
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• pp.485-492
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• 2021

무인항공기의 영상 기반 자동 정밀 착륙 기술은 착륙 지점에 대한 정밀한 위치 추정 기술과 착륙 유도 기술이 요구된다. 또한, 안전한 착륙을 위하여 지상 장애물에 대한 착륙 지점의 안전성을 판단하고, 안전성이 확보된 경우에만 착륙을 유도하도록 설계되어야 한다. 본 논문은 자동 정밀 착륙을 수행하기 위하여 영상 기반의 항법과 착륙 지점의 안전성을 판단하기 위한 알고리즘을 제안한다. 영상 기반 항법을 수행하기 위해 CNN 기법을 활용하여 착륙 패드를 탐지하고, 탐지 정보를 활용하여 통합 항법 해를 도출한다. 또한, 위치 추정 성능을 향상시키기 위한 칼만필터를 설계 및 적용한다. 착륙 지점의 안전성을 판단하기 위하여 동일한 방식으로 장애물 탐지 및 위치 추정을 수행하고, LSM을 활용하여 장애물의 속도를 추정한다. 추정한 장애물의 상태를 활용하여 계산한 CPA를 기반으로 장애물과의 충돌 여부를 판단한다. 최종적으로 본 논문에서 제안된 알고리즘을 비행 실험을 통해 검증한다.

• 한국항행학회논문지
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• 제19권1호
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• pp.1-6
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• 2015

전 세계적으로 급속하게 증가하는 항공교통량으로 인해 ICAO는 기존의 항행장비를 위성항법 기반으로 대체해 나가고 있으며, 이의 일환으로 기존의 ILS를 이용한 이착륙 서비스를 GBAS 로 대체할 계획을 수립 하였다. GBAS는 활주로까지 항공기를 유도하는 정밀 접근 서비스와 공항 주위의 정밀위치정보 서비스를 제공하는 위성항법 보강시스템을 이용하여 ILS와 달리 한 개의 시스템으로 활주로의 수에 관계없이 요구 성능을 제공할 수 있으며 curved approach가 가능하다는 장점을 보유하고 있다. 본 논문에서는 태안비행장 비행시험을 통한 ILS접근 절차와 GBAS curved approach절차를 비교하여 비행시간 단축 및 연료 감소효과를 분석하였으며 실제 비행시험을 통하여 이를 측정 확인 하였다.

• 항공우주시스템공학회지
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• 제16권4호
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• pp.77-87
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• 2022

PADS(Precision Aerial Delivery System)은 원형 낙하산을 이용한 공중 물자수송 시스템의 낮은 착륙 정확도를 개선해줄 수 있는 장비로 AGU(Airborne Guidance Unit)을 장착하여 원하는 목적지로 안전하게 물자를 수송할 수 있다. 현재 외국에서 개발된 PADS 성능은 착륙 정확도가 CEP₅₀ 100m 범위로 보고되고 있으나 실제 지형 및 기상환경에 따라 많은 차이를 보인다. 산악지역이 많은 국내 환경에서는 국부적인 지형변화에 따른 풍향, 풍속 변화가 심하고 이는 착륙 정밀도에 영향을 미친다. 본 연구에서는 이러한 문제점을 해결하기 위해 PADS의 6DOF 비선형 모델링을 기반으로 HILS(Hardware In the Loop Simulation)를 구축하여 바람 환경에서 Ram air parachute의 기동 특성을 분석하였다. 이러한 기동 특성을 고려하여 EM(Energy Management) 기동과 FA(Final Approach) 기동을 포함한 정밀 연착륙 알고리즘을 설계하였다. PADS 시뮬레이션 결과 CEP₅₀ 40m 이내로 정밀 연착륙이 가능하였으며, 향후 이러한 연구 결과를 바탕으로 실제 PADS 투하시험을 통하여 정밀 공중 물자수송 시스템에 적용될 수 있을 것이다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1998년도 제13차 학술회의논문집
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• pp.41-46
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• 1998

In this paper, a stochastic approach based on a Monte Carlo simulation method for the design of a guidance and control (G & C) system of an automatic landing flight experiment (ALFLEX) vehicle is presented. The aim of this study is to design a G & C system robust against uncertainties in the vehicular dynamics. In this study, uncertain parameters and disturbances are treated as random variables in the Monte Carlo simulation. Then, some controller gains in the G & C system are tuned to satisfy conditions concerning the states at touchdown. The proposed method was applied to the ALFLEX vehicle. The simulation results shored the effectiveness of the present approach.

• 한국군사과학기술학회지
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• 제15권6호
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• pp.746-753
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• 2012

ROK military helicopters are frequently exposed to the hazard situations due to the characteristic of operation. Especially, helicopter accident may lead to critical damage of human and structure. Accordingly, pilots have to train the autorotation procedures and learn the skill to prevent hard landing. In this paper, the behavior of skid gear subject to the helicopter autorotation was conducted by using numerical method. The computer simulation approach by using finite element method was employed to accomplish this goal. Additionally, the behavior of skid gear was evaluated for the different landing conditions. In conclusion, the maximum stress concentration was occurred at the attached area of skid cross-tube to the fuselage. Also, it was revealed that the most proper attitude was level landing to prevent hard landing.

• 한국항행학회논문지
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• 제27권6호
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• pp.804-814
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• 2023

인구밀도가 높은 도심지 내에서 비행하게 되는 UAM의 비행경로 하부 및 주변으로는 각종 건축물이 산재하게 된다. 그리고 UAM이 이착륙하는데 사용하는 버티포트는 도심 내의 평지 또는 건축물 상부 등에 위치하게 된다. 이처럼 UAM은 인구밀도가 높은 도심에서 운항하고, 이착륙을 위한 버티포트는 인구밀집지역에 설치됨에 따라 매우 높은 수준의 안전도가 요구된다. 특히 UAM의 안전한 착륙을 위해 최종접근진로에서 버티포트로 접근하는 UAM의 접근상태를 감시하고 접근정보를 제공할 필요가 있다. 이에 UAM 버티포트 최종접근진로 감시를 위해 좁은 부지에 설치가 가능하면서 전자파의 부담이 적다는 장점이 있는 광학장비를 활용하는 기술에 대한 연구를 진행하였다.

• 한국운동역학회지
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• 제21권4호
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• pp.437-447
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• 2011

In this study, the lower limbs joints were analyzed for features based on the biomechanical characteristics of landing techniques according to height and landing on the ground type (flats and downhill). In order to achieve the objectives of the study, changes were analyzed in detail contents such as the height and form of the first landing on the ground at different angles of joints, torso and legs, torso and legs of the difference in the range of angular motion of the joint, the maximum angular difference between joints, the lower limbs joints difference between the maximum moment and the difference between COM changes. The subjects in this study do not last six months did not experience joint injuries 10 males in 20 aged were tested. Experimental tools to analyze were the recording and video equipment. Samsung's SCH-650A model camera was used six units, and the 2 GRF-based AMTI were used BP400800 model. 6-unit-camera synchronized with LED (photo cell) and Line Lock system were used. the output from the camera and the ground reaction force based on the data to synchronize A/D Syc. box was used. To calculate the coordinates of three-dimensional space, $1m{\times}3m{\times}2m$ (X, Y, Z axis) to the size of the control points attached to the framework of 36 markers were used, and 29 where the body was taken by attaching a marker to the surface. Two kinds of land condition, 40cm and 60cm in height, and ground conditions in the form of two kinds of flat and downhill slopes ($10^{\circ}$) of the landing operation was performed and each subject's 3 mean two-way RM ANOVA in SPSS 18.0 was used and this time, all the significant level was set at a=.05. Consequently, analyzing the landing technique as land form and land on the ground, the changes of external environmental factors, and the lower limbs joints' function in the evaluation were significantly different from the slopes. Landing of the slop plane were more load on the joints than landing of plane. Especially, knee extensor moment compared to the two kinds of landing, slopes plane were approximately two times higher than flat plane, and it was statistical significance. Most of all not so much range of motion and angular velocity of the shock to reduce stress was important. In the further research, front landing as well as various direction of motion of kinetic, kinetic factors and EMG variables on lower limbs joints of the study in terms of injury-prevention-approach is going to be needed.

• Advances in aircraft and spacecraft science
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• 제4권5호
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• pp.529-541
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• 2017

Landing phase is one of the crucial and most important phases during robotic aerospace explorations. It concerns the impact of the landing module of a spacecraft on a celestial body. Risks and uncertainties of landing are mainly due to the morphology of the surface, the possible presence of rocks and other obstacles or subsidence. The present work quotes results of a computational analysis direct to investigate the stability during the landing phase of a lander on Phobos, a Mars Moon. The present study makes use of available software tools for the simulation analyses and results processing. Due to the nature of the system under consideration (i.e., large displacements and interaction between several systems), multibody simulations were performed to analyze the lander's behavior after the impact with the celestial body. The landing scenario was chosen as a result of a DOE (Design of Experiments) analysis in terms of lander velocity and position, or ground slope. In order to verify the reliability of the present multibody methodology for this particular aerospace issue, two different software tools were employed in order to emphasize two different ways to simulate the crash-box, a particular component of the system used to cushion the impact. The results show the most important frames of the simulations so as to provide a general idea about how lander behaves in its descent and some trends of the main characteristics of the system. In conclusion, the success of the approach is demonstrated by highlighting that the results (crash-box shortening trend and lander's kinetic energy) are comparable between the two tools and that the stability is ensured.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.206-209
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• 2011

During landing approach, an airplane could experience dynamic unstable motion by the combination of a gust and elevator control to cancel the disturbances. This situation is dangerous and could lead to a loss of an airplane. In this paper, numerical analysis was used to study the effect of pitch oscillating 2-D high lift devices in a landing condition. Experimental data on a pitching naca0012 airfoil was used for code validation. Dynamic characteristics of an airfoil, single slotted flap for mid-class passenger aircraft were analyzed. Unsteady Navier-Stokes analysis was performed with Spalart-Allmaras turbulence model for separation dominant low speed flow. As a result, flow hysteresis of a flapped airfoil was more complex than that of an oscillating airfoil. So, dynamic analysis of a flap in a landing condition is very important for operational safety.

• 제어로봇시스템학회논문지
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• 제18권9호
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• pp.837-844
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• 2012

We introduce a pattern generation method for a hopping one-legged robot and verify it experimentally. The pattern is derived from the liner and angular momentum of a COM (Center of Mass), which are pre-scheduled. Because of the relation between angular velocities of joints and momemtums of the COM, joint angle trajectories are easily obtained. In addition, the landing impact force is reduced by only adjusting the landing timing. In the experiment, the one-legged robot hops in place with 0.06 s of flying time, and makes continuous hopping. Based on our experimental results, the proposed method can be applied to hopping and running of biped humanoid robots.