• Title/Summary/Keyword: Small UAVs

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A Development of DDS Based Chirp Signal Generator and X-Band Transmitter-Receiver for Small SAR Sensor (DDS 기반의 소형 SAR 시스템 송수신장비 개발)

  • Song, Kyoung-Min;Lee, Ki-Woong;Lee, Chang-Hyun;Lee, Woo-Kyung;Lee, Myeong-Jin
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.3
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    • pp.326-329
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    • 2016
  • UAVs(Unmanned Aerial Vehicle) can be used in variant fields fornot only combat, but also recon, observation and exploration. Moreover, UAVs capacity can be expanded to impossible missions for existing surveillance system such as SAR(Synthetic Aperture Radar) technology that collecting images from all weather conditions. In recent days, with development of highly efficient IC and lightened system technology, there are significant increase of researches and demands to make SAR sensor as a payload of UAV. Therefore, this paper contains development process and results of small signal generator and RF device as a core module of SAR system based on the digital device of DDS.

Assessing Stream Vegetation Dynamics and Revetment Impact Using Time-Series RGB UAV Images and ResNeXt101 CNNs

  • Seung-Hwan Go;Kyeong-Soo Jeong;Jong-Hwa Park
    • Korean Journal of Remote Sensing
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    • v.40 no.1
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    • pp.9-18
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    • 2024
  • Small streams, despite their rich ecosystems, face challenges in vegetation assessment due to the limitations of traditional, time-consuming methods. This study presents a groundbreaking approach, combining unmanned aerial vehicles(UAVs), convolutional neural networks(CNNs), and the vegetation differential vegetation index (VDVI), to revolutionize both assessment and management of stream vegetation. Focusing on Idong Stream in South Korea (2.7 km long, 2.34 km2 basin area)with eight diverse revetment methods, we leveraged high-resolution RGB images captured by UAVs across five dates (July-December). These images trained a ResNeXt101 CNN model, achieving an impressive 89% accuracy in classifying vegetation cover(soil,water, and vegetation). This enabled detailed spatial and temporal analysis of vegetation distribution. Further, VDVI calculations on classified vegetation areas allowed assessment of vegetation vitality. Our key findings showcase the power of this approach:(a) TheCNN model generated highly accurate cover maps, facilitating precise monitoring of vegetation changes overtime and space. (b) August displayed the highest average VDVI(0.24), indicating peak vegetation growth crucial for stabilizing streambanks and resisting flow. (c) Different revetment methods impacted vegetation vitality. Fieldstone sections exhibited initial high vitality followed by decline due to leaf browning. Block-type sections and the control group showed a gradual decline after peak growth. Interestingly, the "H environment block" exhibited minimal change, suggesting potential benefits for specific ecological functions.(d) Despite initial differences, all sections converged in vegetation distribution trends after 15 years due to the influence of surrounding vegetation. This study demonstrates the immense potential of UAV-based remote sensing and CNNs for revolutionizing small-stream vegetation assessment and management. By providing high-resolution, temporally detailed data, this approach offers distinct advantages over traditional methods, ultimately benefiting both the environment and surrounding communities through informed decision-making for improved stream health and ecological conservation.

Automated Wireless Recharging for Small UAVs

  • Jung, Sunghun;Ariyur, Kartik B.
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.3
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    • pp.588-600
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    • 2017
  • We develop a wireless, contact free power transfer mechanism that is safer than the direct metallic contact and robust to imperfect alignment on landing at the base station. A magnetic field is created using inductors on both the transmitting and receiving sides. We use the inductive wireless recharging to increase autonomy and decrease the sensor interference by reducing the inductor loop size. By locating four independent small receiver loops and corresponding four circuits around the quadrotor UAV, we can increase safety from circuit malfunctions in comparison to the use of just one loop. On the base station, four folding robotic bars are used to realign the receiver loops over the transmitter loops. After adequate recharging as measured by battery voltages or power consumption at the bae station, the UAV sends a signal to the base station to open the robotic bars and takes off once freed from the robotic bars.

Study on the Optimal Deployment of the Passive Radar System for Detecting Small Unmanned Aerial Vehicles (소형 무인기 탐지를 위한 패시브 레이더망 최적 배치 연구)

  • Baek, Inseon;Lee, Taesik
    • Journal of the Korea Institute of Military Science and Technology
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    • v.19 no.4
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    • pp.443-452
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    • 2016
  • Current low-altitude radar system often fails to detect small unmanned aerial vehicles (UAV) because of their small radar cross section (RCS) compared with larger targets. As a potential alternative, a passive bistatic radar system has been considered. We study an optimal deployment problem for the passive bistatic radar system. We model this problem as a covering problem, and develop an integer programming model. The objective of the model is to maximize coverage of a passive bistatic radar system. Our model takes into account factors specific to a bistatic radar system, including bistatic RCS and transmitter-receiver pair coverage. Considering bistatic RCS instead of constant RCS is important because the slight difference of RCS value for small UAVs could significantly influence the detection probability. The paired radar coverage is defined by using the concept of gradual coverage and cooperative coverage to represent a realistic environment.

Privacy Protection from Unmanned Aerial Vehicle (무인항공기 사생활 보호 방안)

  • Lee, Bosung;Lee, Joongyeup;Park, Yujin;Kim, Beomsoo
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.26 no.4
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    • pp.1057-1071
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    • 2016
  • Privacy-right infringement using unmanned aerial vehicle (UAV) usually occurs due to the unregistered small UAV with the image data processing equipment. In this paper we propose that privacy protection acts, Personal Information Protection Act, Information and Communications Network Act, are complemented to consider the mobility of image data processing equipment installed on UAV. Furthermore, we suggest the regulations for classification of small UAVs causing the biggest concern of privacy-right infringement are included in aviation legislations. In addition, technological countermeasures such as recognition of UAV photographing and masking of identifying information photographed by UAV are proposed.

Implementation of Multilateral Control System for Small UAV Control-Focused on Design (소형 무인기 통제를 위한 다자간 방식 관제시스템 구축방안-설계 중심으로)

  • Choi, Hyun-Taek;Kim, Seok-Kwan;Ryu, Gab-Sang
    • Smart Media Journal
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    • v.6 no.4
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    • pp.65-71
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    • 2017
  • In this paper, we propose a design method for the construction of LTE-based small unmanned aerial vehicle control system to quickly and reliably collect multiple small unmanned aerial vehicle position information simultaneously flying all over the country. In particular, the main requirements are the network (N/W), hardware (H/ W), software(SW), Database(DB), development architecture, and business needs. To satisfy these requirements, N/W, H/W, SW, DB design, and architectural design plan were suggested regarding the design requirements of a small UAV system. To effectively control the small unmanned multi-party system in the system design, the architecture is divided into the front-end service area and the back-end service area according to the function and role of the unit system. In the front-end service area that grasps and controls the position and state of small unmanned aerial vehicles (UAVs), we have studied the design part that can be expanded to N through TCP/IP network by applying Client PC method.

Small UAV tracking using Kernelized Correlation Filter (커널상관필터를 이용한 소형무인기 추적)

  • Sun, Sun-Gu;Lee, Eui-Hyuk
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.20 no.1
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    • pp.27-33
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    • 2020
  • Recently, visual object detection and tracking has become a vital role in many different applications. It spans various applications like robotics, video surveillance, and intelligent vehicle navigation. Especially, in current situation where the use of UAVs is expanding widely, detection and tracking to soot down illegal UAVs flying over the sky at airports, nuclear power plants and core facilities is becoming a very important task. The remarkable method in object tracking is correlation filter based tracker like KCF (Kernelized Correlation Filter). But it has problems related to target drift in tracking process for long-term tracking. To mitigate the target drift problem in video surveillance application, we propose a tracking method which uses KCF, adaptive thresholding and Kalman filter. In the experiment, the proposed method was verified by using monochrome video sequences which were obtained in the operational environment of UAV.

Vision-based Target Tracking for UAV and Relative Depth Estimation using Optical Flow (무인 항공기의 영상기반 목표물 추적과 광류를 이용한 상대깊이 추정)

  • Jo, Seon-Yeong;Kim, Jong-Hun;Kim, Jung-Ho;Lee, Dae-Woo;Cho, Kyeum-Rae
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.3
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    • pp.267-274
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    • 2009
  • Recently, UAVs (Unmanned Aerial Vehicles) are expected much as the Unmanned Systems for various missions. These missions are often based on the Vision System. Especially, missions such as surveillance and pursuit have a process which is carried on through the transmitted vision data from the UAV. In case of small UAVs, monocular vision is often used to consider weights and expenses. Research of missions performance using the monocular vision is continued but, actually, ground and target model have difference in distance from the UAV. So, 3D distance measurement is still incorrect. In this study, Mean-Shift Algorithm, Optical Flow and Subspace Method are posed to estimate the relative depth. Mean-Shift Algorithm is used for target tracking and determining Region of Interest (ROI). Optical Flow includes image motion information using pixel intensity. After that, Subspace Method computes the translation and rotation of image and estimates the relative depth. Finally, we present the results of this study using images obtained from the UAV experiments.

Design of a Low-Power RF Transceiver for Small UAVs Using Switching Power (전원 스위칭을 이용한 저전력 소형무인기용 RF 송수신기 설계)

  • Kim, Hyo-Jong;Lee, Jong-Wook
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.28 no.10
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    • pp.779-787
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    • 2017
  • In this paper, we designed a RF transceiver for small unmanned aerial vehicle(UAV) using power switching method. To apply for the UAV, several characteristics such as size, weight, and power consumption are very important. To reduce power consumption, we propose a new power switching method. Using the proposed method, we fabricated the RF transceiver needed to establish the data link for a small UAV. The fabricated RF transceiver shows an output power of +25 dBm, a noise figure of 4.56 dB and a received signal strength of -100 dBm. By performing power measurement of proposed switching method, 25 % of power could be reduced. The size of the fabricated RF transceiver is $100{\times}60{\times}5.7mm^3$ and the weight is as small as 38 g.

Aerodynamic Design and Performance Prediction of Highly-Loaded 1 Stage Axial Compressor (고부하 1단 축류형 압축기 공력 설계 및 성능 예측)

  • Kang, Young-Seok;Park, Tae-Choon;Yang, Soo-Seok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.11a
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    • pp.101-104
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    • 2010
  • Recently, needs for UAVs and small aircraft and small turbo jet or turbo fan engines for these air-crafts are increasing. Size and weight are the two main restrictions in small air-crafts such as UAV or VLJ propulsion system applications. Therefore, high power density is required in small size and designers come up with unconventional solutions in the design of small aero gas turbine engines. One of the solutions is the usage of highly loaded axial compressors. This paper introduces an aerodynamic design method of a highly loaded axial compressor and its review process. Numerical simulation has been carried out to assess the aerodynamic performance of the compressor.

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