• 한국항공운항학회:학술대회논문집
• /
• 2006.05a
• /
• pp.100-103
• /
• 2006

• Journal of computational fluids engineering
• /
• v.11 no.4 s.35
• /
• pp.48-55
• /
• 2006

A computational study was carried out in order to investigate aerodynamic characteristics on leading edge sweepback angles of Flying-Wing configurations. The viscous-compressible Navire-Stokes equation and Spalart-Allmaras turbulence model of the commercial CFD code were adopted for this computation analysis. This investigation examined aerodynamic characteristics of three different types of leading edge sweepback angles: $30^{\circ}C,\;35^{\circ}C\;and\;40^{\circ}C$. The freestream Mach number was M=0.80 and the angle of attack ranged from ${\alpha}=0^{\circ}C\;to\;{\alpha}=20^{\circ}C$. The results show that the increases in sweepback angle of the Flying-Wing configuration creates more efficient aerodynamic performance.

• 한국항공운항학회:학술대회논문집
• /
• 2005.11a
• /
• pp.160-163
• /
• 2005

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.47 no.6
• /
• pp.422-428
• /
• 2019

A tailless or Blended-Wing-Body(BWB) shaped configuration is highlighted for UCAV with low RCS characteristics. The BWB configuration is characterized by its directional static instability and low controllability. To control the directional movement of the BWB configured vehicle, directional thrust vectoring equipment or drag rudder typed control surfaces which utilize the drag differences of the wing can be considered. This paper deals with a BWB shaped configuration using a spoiler and describes the lateral-directional aerodynamic characteristics of the vehicle. In addition, it is shwon that the lateral-directional motion can be controlled effectively by using the classical PI control structure. This control law is verified by flight test and showed adequate for the tailless BWB shaped UAV.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.40 no.6
• /
• pp.467-474
• /
• 2012

UAVs for reconnaissance and intelligence operations require long endurance capability, which demands high efficiency of the propulsion system. The distributed propulsion system(DPS) generates the thrust by replacing a large propulsion system with a number of small propulsion systems. A DPS distributed along the wing span can produce gains in propulsion efficiency by reducing ejection velocity. Also, the ingestion of boundary layers through the distributed DPS inlet and ejecting flow from the outlet can improve the lift to drag ratio of the vehicle. This study investigates the effects of locations and size of the inlet and outlet of the DPS on the blended-wing-body design based on Eppler 337 airfoil, with a CFD tool. The fans in the DPS are modeled as actuator disks for computational efficiency. The best location and aspect ratio of the inlet and outlet are found from lift-to-drag ratio and pitching moment considerations.

• Proceeding of EDISON Challenge
• /
• 2014.03a
• /
• pp.550-555
• /
• 2014

전익기는 전쟁 중 등장해 활약했다는 점과 그 독특한 형태로 유명세를 타기 시작한 비행체의 한 종류이다. 공기역학적으로 동일한 속도로 비행할 때 일반적인 항공기와 비교해서 적은 동력으로 더 멀리 날수 있는 전익기의 특성과 그 발전방향을 보았을 때 동체의 익면적이 넓어 생기는 특성을 극대화 시키면서 더욱 독특한 형태의 비행체로 나타나는 모습이 원반형 비행체이다. 본 연구는 EDISON Simulation을 활용한 두 비행체의 공력특성 비교를 통해 실제로 원반형 비행체가 많이 쓰이지 않는 이유와 그 장단점에 대한 데이터를 확보했으며 특히 원반형 비행체의 경우 Cockpit 유무와 그 크기에 따라 실속각이 커지는 것을 확인하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.10
• /
• pp.809-819
• /
• 2020

In this study, the twist angle and wing planform shapes were selected as design variables and optimized to secure the stability of the flying-wing type UAV. Flying-wing aircraft has no separated fuselage and tails, which has advantages in aerodynamic characteristics and stealth performance, but it is difficult to secure the flight stability. In this paper, the sweep back angle and twist angle were optimized to obtain the lateral stability, the static margin and wing planform shapes were optimized to improve the longitudinal stability of the flying-wing, then effect of the twist angle was confirmed by comparing the stability of the shape with the winglet and the shape with the twist angle. In the optimization formulation, focusing on improving stability, constraints were established, objective functions and design variables were set, then design variable sensitivity analysis was performed using the Sobol method. AVL was used for aerodynamic analysis and stability analysis, and SQP was used for optimization. The CFD analysis of the optimized shape and the simulation of the dynamic stability proved that the twist angle can be applied to the improvement of the lateral stability as well as the stealth performance in the flying-wing instead of the winglet.

• 한국노년학
• /
• v.28 no.4
• /
• pp.953-968
• /
• 2008

This research was performed to recognize anxiety level of older people, to find out anxiety level after or before regular exercises, and to find out how much anxiety level could be lowered by the sports activities. This research selected a population among the students who enrolled at sport activity classes (e, g., physical exercises, gate ball, volume dance) at L, S, J, Y (a), Y (b), D older people college located in Seoul and Gyoenggi area. 200 of the population were chosen as candidates by convenience sampling, nonprobability sampling. Considering the age of the candidates, total 200 cases were collected by using two methods (survey and interview) simultaneously. The data assessment was made by SPSS 12.0 Version. Error tolerance in statistics is .05. The data was analyzed by using frequency analysis, paired t-test and independent t-test. After analyzing anxiety awareness level after and before regular exercises, anxiety of older people are classified by four factors. First, anxiety for loss is 3.756 (M=3.756) before exercises, while 1.942 (M=1.942) after exercises. Second, fear for aging is 3.443 before exercises and 2.243 after exercises. Third, anxiety for physical appearance is 3.253 before exercises and 2.310 after exercises. Finally, anxiety caused by psychological insecurity is 3.060 before exercises, while 1.666 after exercises. Error of tolerance for all factors falls within .001. Anxiety score after exercises is lower than that of before exercises for every factor as well. As a result, regular physical exercises appeared to reduce anxiety level of older people.