• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.1
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• pp.24-29
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• 2015

In order to increase endurance flight efficiency of long endurance electric powered UAV, main wing of UAV should have high aspect ratio and low structural weight. Since a spar which consists of thin and slender structure for weight reduction can cause catastrophic failure during the flight, it is important to develop verification method of structural integrity of the spar with the light weight design. In this paper, process of structural analysis using non-linear finite element method was introduced for the verification of structural integrity of the spar. The static strength test of the spar was conducted to identify structural characteristic under the static load. Then, the experimental result of the spar was compared to the analytical result from the non-linear finite element analysis. It was found that the developed process of structural analysis could predict well the non-linear structural behavior of the spar under ultimate load.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.285-288
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• 2005

A Stratospheric airship should stay long to achieve its original mission. Meanwhile, to obtain what the solar radiation and heat transfer have an effect on Stratospheric condition, heat analysis has been done. For this work, Stratospheric heat condition's been examined and for the numerical analysis, by using Gridgen, grids of airship have been generated. And by using STAR-CD, the study about heat characteristic of airship model was carried out. Especially, with changing the position of the Sun, the temperature change of the airship body was focused on. With this background, the possibility of realizing the simulation of the effects solar radiation have on the Stratospheric airship.

• Journal of Aerospace System Engineering
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• v.9 no.2
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• pp.1-6
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• 2015

태양광 고고도 장기체공형 무인기나 인간동력 항공기 등에 사용되는 높은 종횡비를 가진 유연날개는 공력 및 구조 상호작용으로 인하여, 구조적 비선형 처짐 및 양력감소 등의 문제가 발생한다. 본 연구에서는 저속 비행하는 높은 종횡비를 가진 날개의 단방향 공력-구조 연계해석을 수행하였다. XFOIL을 사용하여 공력천이현상을 포함한 저 레이놀즈수 익형 공력특성 자료 확보를 기반으로 3차원 양력선 이론을 사용하여 공력해석 연구를 수행했다. 구조해석은 상용소프트웨어 ANSYS를 사용하여 구조변형이나 응력해석 연구를 수행했다. 단방향 공력-구조 연계해석 결과를 바탕으로 인간동력 항공기 주 날개의 형상설계 연구를 수행했다.

• Journal of Aerospace System Engineering
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• v.10 no.4
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• pp.50-58
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• 2016

In our preceding study, we reported that the use of light, composite-material wings in long-endurance Solar-Powered UAVs is a critical factor. Ribs are critical components of wings, which prevent buckling and torsion of the wing skin. This study was undertaken to design and manufacture optimal composite ribs. The ribs were manufactured by applying laminated-layer patterns and shapes, considering the anisotropic properties of the composite material. Through the finite element analysis using the MSC Patran/Nastran, the maximum load and the displacement shape were identified. Based on the study results measured by structural tests, we present an optimal design of ribs.

• Aerospace Engineering and Technology
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• v.3 no.2
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• pp.248-255
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• 2004

In this study, aerodynamic shape design of airfoils was performed by using RSM(response surface method) and two-dimensional Navier-Stokes solver. Numerical experiment points were determined by D-optimal method and quadratic response surfaces were constructed by using JMP. For the validations of design method, NACA 64621 airfoil was inversely designed to have aerodynamic characteristics of Bell airfoil. The design method was applied to the aerodynamic design of both smart UAV wing airfoil and low Reynolds rotor-blade airfoil for unmanned helicopter. The optimized airfoils showed improved performance with various constraint conditions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.7
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• pp.590-600
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• 2012

In this research, generalized sizing methods were studied that can be applied to an aircraft which uses solar cell or fuel cell as energy sources. To consider multiple propulsion systems and energy resources, multiple power paths were modeled and the weight of consumable and non-consumable energy was reflected in the weight change calculation for each mission segments. In the constraint analysis, power to weight ratio was selected instead of thrust to weight ratio and used in the sizing process of balancing power and energy.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.8
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• pp.26-33
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• 2005

Smart UAV, which adopting tiltrotor aircraft concept, requires vertical take-off and landing, long endurance and high speed capability. These contradictable flight performances are hard to meet unless the operation of flap system which should reveal optimal performance for each flight mode. In order to design SUAV flaperon satisfying the three performance requirements, various configurations are generated and their aerodynamic performances are analyzed using numerical flow computations around flap systems. Considering aerodynamic performance and structural simplicity, a final flap configuration is selected and the performance is validated through the wind tunnel testing for 40% scale model.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.3
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• pp.31-36
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• 2006

In this study, nonlinear static aeroelastic analysis system for a high-aspect-ratio wing are developed using the transonic small disturbance (TSD) and large deflection beam theory and validated. For the coupling between fluid and structure, the transformation of displacement from the structural mesh to aerodynamic one is performed by the shape function of the beam finite element and the inverse transformation of force by work equivalent load concept. Also, for the static aeroelastic analysis of the wing the use of TSD aerodynamics are justified. The validation of the system includes one of the efficient transformation methods of force and displacement.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2016.11a
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• pp.426-427
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• 2016

본 논문에서는 Unmaned Aerial Vehicle(UAV)를 이용하여 양식어장에 유입될 수 있는 적조 모니터링에 대한 연구를 실시하였다. 적조는 한반도 주변 해역을 포함한 전 세계 연안 지역에서 물고기의 집단 폐사, 해안구조물에 대한 물리적 손상등과 같이 사회 경제적인 피해를 야기 시켜왔고, 최근 해수면 온도상승과 같은 기후 변화에 의한 영향으로 증가되고 있는 실정이다. 특히 남해안과 같이 생활하수가 다량 유입되고 저층에 퇴적된 영양물질이 용출되는 곳에서 상습적으로 발생한다. 1995년에 발생한 코클로디니움에 의한 적조는 764억원의 기록적인 피해를 입히면서, 적조에 대한 신속한 대응과 효과적인 방제작업의 필요성이 대두되었다. 이렇게 양식어장 운영에 다양한 문제가 발생이 된 후 대응하는 것보다 모니터링을 통해 사전에 유입을 차단하고 대처하는 연구가 필요하고 판단된다. 원격탐사를 활용한 적조 탐지 및 모니터링 연구는 UAV에서 취득한 RGB color 영상을 통한 적조 추출 및 분석, 시계열 분석을 위한 영상자료 수집, 현장관측 자료와 위성영상에서 추출한 클로로필 농도 비료글 통해 이루어 졌다. 또한 매년 발생하는 적조생물에 관한 속성정보를 통해 적조발생지역에 대한 적조생물종과 국내 연안에서 발생한 적조의 발생 범위 등의 정보를 지리정보기반에 의한 공간분석을 실시하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.4
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• pp.133-140
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• 2018

Recently, environmentally friendly aviation propulsion systems have received a lot of attention. Therefore, many studies have been conducted on the development of UAVs and propulsion systems that can perform missions while relying on a combination of various power sources. In this paper, we show the design results of a hybrid propulsion system based on solar-power generation. It integrates a single system to test reliability and performance. Finally, a verification test is conducted on the aircraft to confirm the function and normal operation of the system before a flight test.