• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.11a
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• pp.163-164
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• 2016

이전까지 많은 연구자들은 적응 신호처리(Adaptive Signal Process)를 이용한 잡음 제거 방법을 연구해 왔다. 그러나, 최근 발전하고 있는 멀티콥터는 프로펠러 모터의 RPM(Revolution Per Minute)이 실시간으로 변하기 때문에 적응 신호처리를 이용하여도 깔끔한 결과를 얻어 내기가 어렵다는 한계가 존재한다. 또한, 특정 주파수를 기준으로 형성되는 고조파(Harmonics)는 적응 알고리즘인 (N)LMS 를 이용한 예측에서 오차를 발생시키는 문제를 발생시킨다. 따라서, 본 논문에서는 멀티콥터를 이용한 음향 취득에 대한 소음 저감 방법으로 회전 속도계(Tachometer), 콤 필터(Comb Filter), NLMS 알고리즘(Normalized Least Mean Square Algorithm)을 이용한 방법을 제안한다.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.29 no.1
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• pp.61-73
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• 2021

PAV is considered to improve quality of life and standards of living, improvement of which was caused by automobile hundred years ago. Comparative economic efficiency of PAVs is measured to compare each PAV. Specification and sales price of the PAVs are open to the public. BlackFly, Transition and Aeromobil 3.0 have competitive power in flying range, purchasing cost, and operational cost. Lift & cruise configuration and vectored thrust configuration PAVs are designed by many companies nowadays, and BlackFly which can be considered to be lift & cruise configuration is one of the most efficient PAVs. High battery price does not help multi-copter shaped PAVs to have economic efficiency. Aerodynamic wing, eVTOL, and low sale price are needed for PAVs to ride a wave of public interest as a new personal mobility. Under the conditions, the PAV can fly at downtown and can be purchased by people at large. Popularization of PAV could follow in the 100 years old footsteps of automobile.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.4_2
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• pp.663-671
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• 2022

Practice through virtual reality can increase the educational effect regardless of time and place, and it is an educational method that is being pursued even in the situation of COVID-19. On the other hand, for VR-based education, related technology development and content development must be made, and experiential methods (flipped learning, blended learning, hybrid learning) must be provided in the educational process. The development scenario was developed with the contents of drone qualification test (ultra-light unmanned multicopter) and drone practice and the possibility of non-face-to-face self-directed learning (flipped learning, blended learning, hybrid learning). It is expected that the quality of vocational education related to drones and the effect of high education will be improved through the contents, and it is thought that it will be possible to suggest a direction for the development of various vocational education contents in non-face-to-face education.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.2
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• pp.595-609
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• 2020

In this study, we propose a decentralized mathematical model for predictive control of a system of multi-autonomous unmanned aerial vehicles (UAVs), also known as drones. Being decentralized and autonomous implies that all members make their own decisions and fly depending on the dynamic information received from other unmanned aircraft in the area. We consider a variety of realistic characteristics, including time delay and communication locality. For this flocking flight, we do not possess control for central data processing or control over each UAV, as each UAV runs its collision avoidance algorithm by itself. The main contribution of this work is a mathematical model for stable group flight even in adverse weather conditions (e.g., heavy wind, rain, etc.) by adding Gaussian noise. Two of our proposed variance control algorithms are presented in this work. One is based on a simple biological imitation from statistical physical modeling, which mimics animal group behavior; the other is an algorithm for cooperatively tracking an object, which aligns the velocities of neighboring agents corresponding to each other. We demonstrate the stability of the control algorithm and its applicability in autonomous multi-drone systems using numerical simulations.

• Journal of Advanced Navigation Technology
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• v.24 no.5
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• pp.358-367
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• 2020

With the increases of average commuting time of office workers in the Seoul metropolitan area and the cost of traffic congestion on roads, the need for new transportation is increasing and urban air mobility (UAM) is emerging as an alternative. Therefore, in this paper, the vertiport locations were selected and routes were established using population, traffic and commuting data of Seoul and Gyeonggi Province. Vector thrust type and multicopter type of eVTOL compatible for UAM were selected by analyzing the types of eVTOLand time required for selected routes was calculated. In addition, the time required when we utilize other transportations was compared with UAM. Finally, it was verified that the commuting time can be sharply reduced when we use UAM.

• Journal of Satellite, Information and Communications
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• v.9 no.2
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• pp.63-68
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• 2014

This paper proposed a novel compressed sensing (CS) technique for an efficient video transmission of multi-copter. The proposed scheme is focused on reduction of the amount of data based on CS technology. First, we describe basic principle of Spectrum sensing. And then we compare AMP(Approximate Message Passing) with CoSaMP(Compressive Sampling Matched Pursuit) through mathematical analysis and simulation results. They are evaluated in terms of calculation time and complexity, then the promising algorithm is suggestd for multicopter operation. The result of experiment in this paper shows that AMP algorithm is more efficient than CoSaMP algorithm when it comes to calculation time and image error probability.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.10a
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• pp.34-37
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• 2019

The drone uses a Microwave Doppler Radar Sensor which operates at 10.525GHz to recognize harmful animal which intruded into the arable land. Moreover provide user with notification services on risk factors. Subsequently, the user the drone's camera and a camera-only app to watch the farmland in real-time, steer the drone directly, and use the NeoPixel LED ring and the speaker to stimulate the harmful animal's sight and hearing to induce escape.

• Journal of Aerospace System Engineering
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• v.15 no.4
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• pp.11-20
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• 2021

The estimation of hovering flight time of multicopters using the battery power propulsion system is important for the development and design of the aircraft and its operation. For a given operational weight, the maximum possible battery weight can be decided using both a conventional energy density method and a new Peukert law. In the present study, the hovering flight time is predicted using both methods. The specific data of multicopters in the published literatures were employed for the computation of the hovering flight time. The results were validated with the measured data. The effect of figure of merit of propeller, battery discharging process on the hovering flight time was evaluated, Finally, the effect of the battery cell and package connection types on the hovering time was investigated. It was found that the combination of serial battery cell connections and parallel package connection is the bast in the endurance maximization aspect. As the cell number increases in a package, the hovering flight time is increased. There exists the max. battery ratio for the given takeoff gross weight.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.8
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• pp.53-59
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• 2022

In this study, an experimental device was fabricated to evaluate the hovering flight performance of a single rotor on a hexacopter used for river surveillance, and a thrust performance test was conducted. In addition, the 3D profile of the propeller was extracted by 3D scanning and CFD analysis was performed using ANSYS CFD 14.5 based on the extracted 3D model of the propeller. The aerodynamic characteristics were compared with the results of the performance tests and CFD analysis, and the vortex structure corresponding to each motor rotational speed in revolutions per minute (rpm) was identified. In the future, we plan to provide valuable data for multicopter propeller design and performance verification.

• Journal of Aerospace System Engineering
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• v.16 no.6
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• pp.74-80
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• 2022

The utilisation of small drones is becoming increasingly widespread particularly in the military sector. In this study, STANAG 4586, a standard interface for military unmanned aerial vehicles, was applied to a multicopter-type small drone to examine the suitability of the military system. To accomplish this, a small multi-copter vehicle was designed and manufactured, integrating a flight control computer, ground control system, and data link. Furthermore, flight control and ground control equipment software were developed by applying the STANAG 4586 interface, followed by HILS and flight tests.