• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.251-256
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• 2008

The experimental analysis on a ducted fan for the propulsion system of a small UAV were performed. To investigate the aerodynamic characteristics of the ducted fan, flow fields at inlet and outlet were measured using a hot-wire anemometry. Thrusts were measured with the six-component balance with due regard to the cross wind. To reproduce the cross wind effect, the ducted fan was aligned to $90^{\circ}$ rotated direction against flow direction in the wind tunnel. In this paper, the variation of the flow fields and thrust according to the cross wind were analyzed.

• Journal of Aerospace System Engineering
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• v.18 no.3
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• pp.76-85
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• 2024

Recently, from a global perspective, the use of small unmanned aerial vehicles in terrorism and warfare is increasing, and the need for anti-drone shooting training targeting small UAVs is increasing. However, in reality, there are many cases in Korea where anti-drone shooting training is restricted, due to complaints such as noise. In this paper, we describe the development and testing of an electric-powered direct strike type high-speed, low-noise small aerial target drone. To achieve the flight speed and endurance required for shooting training, target drone sizing was performed, and aerodynamic performance analysis was conducted using a CFD program. Based on the performance analysis, the motor propulsion system was selected and a variable pitch propeller system was designed, and performance tests were performed on a ground test rig. Finally, the target flight speed, flight time, and flight noise level were confirmed through flight tests.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.1
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• pp.1-12
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• 2022

Wind tunnel test for a small scale electric ducted fan with a 104mm diameter was conducted to analyze the aerodynamic characteristics when it was used as a propulsion system of tilt-propeller UAV. Experimental conditions were derived from flight conditions of a sub-scaled OPPAV. Forces and moments of the ducted fan model were measured by a 6-axis balance and 3-dimensional wake vectors which could induce an aerodynamic influence in the vehicle were measured by 5-hole probes. Thrust and torque on hover and cruise conditions were measured and analyzed to drive out the operating conditions when it was applied in the sub-scaled OPPAV. On transition conditions, thrust keep its value with tilt angle variation below 40° and increase after that. But, sideforce increase constantly until 75°. The maximum axial velocity in the wake on hover and cruise conditions was around 60m/s and tangential velocity was around 12m/s. The position of the maximum axial velocity and vortex center move off the fan rotation center line as the tilt angle increases.

• NEWSLETTER 전기공업
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• no.94-1 s.98
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• pp.27-42
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• 1994

• 한국항공운항학회:학술대회논문집
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• 2004.11a
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• pp.79-84
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• 2004

• 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.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.5
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• pp.445-452
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• 2017

The wing leading edge skin in this research is an essential structural factor for improving wings' aeromechanical functions, protecting the interior elements of the wings from external damage including birds, and navigating planes safely. The study compared and reviewed models manufactured for optimal light-weight wings of composite UAVs. It compared and investigated displacement forms of torsion loads through finite element analysis using MSC. Patran/Nastran. By confirming the improvement of light-weighting performance according to lamination type, thickness change and shape through torsion strength tests of each model, the research suggested the optimal light-weight wing leading edge skin for small composite UAVs.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.261-266
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• 2003

Foil air bearing, which is a noncontact bearing utilizing viscosity of operating fluid and elastic deformation of foil structure, has several advantages over rolling element bearings in terms of oilless environment, long life, high speed operation, and high temperature application over $500^{\circ}C$ . Recently advanced researches are actively being performed for the application to the extreme temperature such as gas turbines, as well as conventional small turbo machinery. In this paper, the principle of foil air bearing is introduced and a feasibility study to adopt a foil bearing as the turbine bearing of 65 HP turbo shaft engine, which is under development for UAV, is presented.

• Journal of Aerospace System Engineering
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• v.11 no.4
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• pp.22-29
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• 2017

A study is performed for the effective detection method of a fault which is occurred during operation in a small turbojet engine with non-linear characteristics used by unmanned air vehicle. For this study the non-linear dynamic model of the engine is derived from transient thermodynamic cycle analysis. Also for inducing real operation conditions the controller is developed associated with unscented Kalman filter to estimate noises. Sequential probability ratio test is introduced as a real time method to detect a fault which is manipulated for simulation as a malfunction of rotational speed sensor contaminated by large amount of noise. The method applied to the fault detection during operation verifies its effectiveness and high feasibility by showing good and definite decision performances of the fault.

• The Optical Journal
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• s.158
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• pp.52-54
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• 2015

최근 무인항공기를 지칭하는 드론 관련 산업이 미래를 이끌 신산업으로 부상하고 있다. 드론은 20세기 초에 군사용으로 개발되어 정찰 감시 및 폭격과 같은 군사임무를 수행하여 왔으나 최근 들어 독일 DHL, 아마존, 구글 등과 같은 다국적 기업들이 상업적 용도로 활용을 선언하며 연구 개발에 뛰어 들면서 그 시장이 예상보다 빨리 커지고 있다. 미국 틸 그룹의 보고서에 의하면 2013년 세계 드론 시장의 규모는 66억 달러였고 그 중 군사용이 90% 이상을 차지하고 있으나 향후 민수용 시장 비율이 상당히 커질 것으로 예상된다. 2022년에는 114억 달러 규모로 커질 것으로 예상하고 있다. 현재 민수용으로 사진 촬영용 소형 드론으로부터 정밀농업, 인프라 관리, 택배 및 화물 수송 등으로 운용 범위를 확대하고 있다. 국내 드론 산업은 군수 위주로 시작되어 세계 7위권의 기술력을 확보한 것으로 평가되고 있다. 무인기 분야의 연구개발은 국방과학연구소와 한국항공우주연구원 등 정부출연연구소가 주도하는 가운데, 한국항공우주산업, 대한 항공이 주로 체계종합(System Integrator) 및 비행체 개발을 담당하고 LIG넥스원, 삼성탈레스, 삼성테크윈 등의 대기업을 포함한 중소업체들이 부체계 기술을 개발하고 있다. 최근 소형 드론을 중심으로 시장형성이 가시화되는 민수 시장에서는 가격, 기술 경쟁력의 열위에 있어, 국내 산업 경쟁력 확보와 미래 시장을 선도할 핵심 제품 개발이 시급한 실정이다. 또한 무인기의 비행체 국산화는 상당한 수준으로 진행되었으나, 광학(EO) 적외선(IR) 카메라 등 핵심 부가가치를 구성하는 탑재 임무장비의 경우 원천기술의 부족으로 해외에 의존하고 있다.