• Title/Summary/Keyword: 유연익형

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Study on Flexible Airfoil in Low Reynolds Number Flow Field (저 레이놀즈 수 유동장에서의 유연 익형에 대한 연구)

  • Gwon, Gi Beom
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.3
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    • pp.1-7
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    • 2003
  • In the study, aeroelastic behaviors and aerodynamic performances of flexible airfoil in low Reynolds number environment are evaluated. To facilitate the present study, flexible airfoil in modeled through attaching massless membrane in portion of the upper CLARK-Y airfoil surface, which is often proposed low Reynolds number airfoil. The behavior of membrane in governed by aerodynamic forces and membrane equilibrium equation. Nondimensional parameter deducted by nondimensionalizing the membrane equilibrium equation, which represents the interaction between fluid and membrane has a great influence on membrane aeroelastic behavior. Changing the starting point of the membrane is conducted on aerodynamic performances. As a result, the value of nondimensional parameter should almost linearly increase according to moving the starting point of the membrane surface toward the trailing edge.

Conceptual Study on Coaxial Rotorcraft UAV for teaming operation with UGV (무인지상차량과의 합동운용을 위한 동축반전 회전익형 무인항공기 개념연구)

  • Byun, Young-Seop;Song, Jun-Beom;Song, Woo-Jin;Kim, Jeong;Kang, Beom-Soo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.39 no.5
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    • pp.458-465
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    • 2011
  • UAV-UGV teaming concept has been proposed that can compensate for weak points of each platform by providing carrying, launching, recovery and recharging capability for the VTOL-UAV through the host UGV. The teaming concept can expand the observation envelop of the UGV and extend the operational capability of the UAV through mechanical combination of each system. The spherical-shaped coaxial rotorcraft UAV is suggested to provide flexible and precise interface between two systems. Hybrid navigation solution that included vision-based target tracking method for precision landing is investigated and its experimental study is performed. Feasibility study on length-variable rotor to provide the compact configuration of the loaded rotorcraft platform is also described.

Static Aerodynamics-Structure Coupling Analysis of a 3D Flexible Wing Flying at Low Speed (저속 비행 3차원 유연날개 정적 공력-구조 연계해석)

  • Han, Hyungseok;Park, Joohee;Lee, Nawon;Han, Cheolheui
    • 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.

Molecular Phylogeny of Veneroidea (Bivalvia: Heteroconchia) on the Basis of Partial Sequences of 28S rRNA Gene (일부 28S rRNA 염기서열을 이용한 백합 상과 패류의 계통분류)

  • Kim, Sei-Chang;Kim, Jae-Jin;Hong, Hyun-Chul
    • The Korean Journal of Malacology
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    • v.21 no.2 s.34
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    • pp.147-161
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    • 2005
  • To elucidate the phylogenetic relation of the superfamily Veneroidea, we obtained partial 28S rRNA sequences of 14 heterodonts and three pteriomorphs which were collected from Korea and the sequence data of related taxa from GenBank, and analyzed maximum parsimony with PAUP program 750 of the nucleotide positions were variable, 560 of which were informative under conditions of parsimony. Total tree length was 2,765, and consistency index, homoplasy index (HI), and Retention index was 0.4843, 0.5157, and 0.6291, respectively. Intraspecific variation of 28 rRNA of Corbicula fluminea and Sinonovacula constricta was 3.1% and 1.3%, respectively. Pitarinae-Cyclininae-Meretrinae group had a clade and Samaranginae, Chioninae, and Dorsininae were clustered.

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