• Journal of the Institute of Convergence Signal Processing
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• v.19 no.2
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• pp.54-60
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• 2018

In this paper, we propose an efficient automatic control method for the collision avoidance of drones. In general, the drones are controlled by transmitting to the flight control (FC) module the received PWM signals transmitted from a RC controller which transduce movements of the knob into PWM signal. We implemented the collision avoidance module in-between receiver and FC module to monitor and change the throttle, pitch and roll control signals to avoid drone collision. In order to avoid the collision, a LiDAR distance sensor and a servo-motor are installed and periodically measure the obstacle distance within -45 degrees from 45 degrees in flight direction. If the collision is predicted, the received PWM signal is changed and transmitted to the FC module to prevent the collision. We applied our proposed method to a hexacopter and the experimental results show that the safety is improved because it can prevent the collision caused by the inadvertency or inexperienced maneuver.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1247-1255
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• 2016

The safety and autonomous flight function of micro UAV or drones is crucial to its commercial application. The requirement of own building stable drones is still a non-trivial obstacle for researchers that want to focus on the intelligence function, such vision and navigation algorithm. The paper present a GCS using commercial drone and hardware platforms, and open source software. The system follows modular architecture and now composed of the communication, UI, image processing. Especially, lane-keeping algorithm. are designed and verified through testing at a sports stadium. The designed lane-keeping algorithm estimates drone position and heading in the lane using Hough transform for line detection, RANSAC-vanishing point algorithm for selecting the desired lines, and tracking algorithm for stability of lines. The flight of drone is controlled by 'forward', 'stop', 'clock-rotate', and 'counter-clock rotate' commands. The present implemented system can fly straight and mild curve lane at 2-3 m/s.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.5
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• pp.981-988
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• 2023

As the usage of unmanned aerial vehicles expands, the development and the demand of related technologies are increasing. As the frequency of operation increases and the convenience of operation is emphasized, the importance of related autonomous flight technology is also highlighted. Establishing a path plan to reach the destination in autonomous flight of an unmanned aerial vehicle is important in guidance and control, and a technology for automatically generating path plan is required in order to maximize the effect of unmanned aerial vehicle. In this study, the optimization research of path planning using rapid-exploring random tree method was performed for increasing the effectiveness of autonomous operation. The path planning optimization method considering the characteristics of the unmanned aerial vehicle is proposed. In order to achieve indexes such as optimal distance, shortest time, and passage of mission points, the path planning was optimized in consideration of the mission goals and dynamic characteristics of the unmanned aerial vehicle. The proposed methods confirmed their applicability to the generation of path planning for unmanned aerial vehicles through performance verification for obstacle situations.

• The Korean Journal of Air & Space Law and Policy
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• v.35 no.2
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• pp.225-246
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• 2020

More than technical or academic matter, mitigation of height restriction around airports is about up-dating out-dated policies that have not kept up with rapidly developing aircraft and air traffic control technologies. Above all, instead of calling out 'flight safety' that the public do not comprehend, it is important to examine and carry out measures that can protect people's right of property. MOLIT(Ministry of Land, Infrastructure, and Transport) after reviewing ICAO's Obstacle Limitation Surface TF, made an announcement to provide further plans that would apply to contracting states from 2026. However, residents of redevelopment areas near Kimpo international airport asserted that MOLIT's policy overlooks the reality of the redevelopment zone. ICAO, UN's specialized agency for civilian aviation, recommends in Annex 14, 4.2.4 that contracting states conduct an aeronautical study to determine the flight safety of horizontal surface(45m), excluding approach surface, and to mitigate height restrictions if no threat is found. Numerous countries including the United States have been following this recommendation and have been able to effectively protect people's right of property, whereas the South Korean government have not following it so far. The number of height restriction mitigation cases in the recent three months (2019. 7. 15~10. 14.) FAA of the United States have allowed after conducting an aeronautical study reaches 14,706. Japan and Taiwan also reconstruct airspace around airports in metropolitan areas in order to protect people's right of property. Just as the United States is following, MLIT should follow ICAO's recommendation in Annex 14. 4.2.4(Vol. 1. Airport Construction / Operation) and protect people's right of property by first applying aeronautical studies to the horizontal surface(45m) of flight safety zones until the specifics of ICAO's 2026 TF materialize.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.5
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• pp.448-454
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• 2008

This paper deals with a behavior based decentralized control strategy for UAV swarming utilizing the artificial potential functions and the sliding mode control technique. Individual interactions for swarming behavior are modeled using the artificial potential functions. The motion of individual UAV is directed toward the negative gradient of the combined potential. For tracking the reference trajectory of UAV swarming, a swarming center is considered as the object of control. The sliding-mode control technique is adopted to make the proposed swarm control strategy robust with respect to the system uncertainties and the varying mission environment. Numerical simulation is performed to verify the performance of the proposed controller.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.12
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• pp.2296-2302
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• 2006

In this paper, we propose a development technique of high precision laser finder ranger within instrument distance 1km, instrument error less than 1 m by using pulse time of flight method in the 5m unit instrument and heterodyne method in the within Am unit. These propose methods can be more advanced to measurement velocity and more highly precision distance instrument not affected the strength of light. We also validate this usefulness.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.539-543
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• 2005

The research presented in this paper enables real-time 3D modeling to help make construction processes ultimately faster, more predictable and safer. Initial research efforts used an emerging sensor technology and proved its usefulness in the acquisition of range information for the detection and efficient representation of static and moving objects. Based on the time-of-flight principle, the sensor acquires range and intensity information of each image pixel within the entire sensor's field-of-view in real-time with frequencies of up to 30 Hz. However, real-time working range data processing algorithms need to be developed to rapidly process range information into meaningful 3D computer models. This research ultimately focuses on the application of safer heavy equipment operation. The paper compares (a) a previous research effort in convex hull modeling using sparse range point clouds from a single laser beam range finder, to (b) high-frame rate update Flash LADAR (Laser Detection and Ranging) scanning for complete scene modeling. The presented research will demonstrate if the FlashLADAR technology can play an important role in real-time modeling of infrastructure assets in the near future.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.2
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• pp.181-190
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• 2014

The optimized flight path planning which is appropriate for UAV operation with high performance and multiplex sensors is required for efficient ISR missions. Furthermore, a mission visualization tool is necessary for the assessment of MoE(Measures of Effectiveness) prior to mission operation and the urgent tactical decision in peace time and wartime. A mission visualization and analysis tool was developed by combining STK and MATLAB, whose tool was used for UAV ISR mission analyses in this study. In this mission analysis tool, obstacle avoidance and FoM(Figure of Merit) analysis algorithms were applied to enable the optimized mission planning.

• Journal of Satellite, Information and Communications
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• v.12 no.1
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• pp.76-80
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• 2017

With the fast growing popularity of small UAVs (Unmanned Aerial Vehicles), recent UAV systems have been designed and utilized for the various field with their own specific purposes. UAVs are opening up many new opportunities in the fields of electronics, sensors, camera, and software for pilots. Increase in awareness and mission capabilities of UAVs are driving innovations and new applications driven with the help of low cost and its capability in undertaking high threat task. In particular, small unmanned aerial vehicles should fly in environments with high probability of unexpected sudden change or obstacle appearance in low altitude situations. In this paper, current researches regarding techniques of autonomous flight of smal UAV systems are introduced and we propose a draft idea for planning paths for small unmanned aerial vehicles in adversarial environments to arrive at the given target safely with low cost sensors.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11A
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• pp.1206-1212
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• 2007

International Civil Aviation Organization(ICAO) adopted VOR(Very high frequency Omni-Range) as an international standard air navigation system in 1949 and recommended every country to make use of it in formulating air route and guiding take-off and landing of an aircraft. VOR is quite a useful navigation system so that more than 2,000 VORs are currently installed all over the world including 39 in the Republic of Korea; however, VOR signal could be easily affected by its circumstance like a mountainous area because it provides navigation information to an aircraft through AM and FM of VHF carrier. There are two types of VOR which are defined according to a design methode. Therefore this study intends to investigate which type of VOR is suitable for mountainous area. For that purpose, the performance of each CVOR and DVOR is measured and analyzed by using an aircraft equipped with measuring instruments. The analyzed result will be applied and utilized in selecting the VOR type, so it could be a feasible solution of problem related to the VOR relocation due to its insufficient performance in the future.