• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.45 no.10
• /
• pp.817-824
• /
• 2017

This paper presents the characteristics of wing-tail interference for a tail-controlled missile. The magnitude of wing-tail interference was calculated with wind tunnel test results and its effects on aerodynamic coefficients were investigated. The downwash angle of tail wing was calculated with experimental data and the effect of wing-tail interference was expressed as a ratio of angle of attack. Numerical simulations were made to examine flow characteristics of wing-tail interference and the vorticity contour of missile were compared with respect to angle of attack. Experimental and numerical analysis results show that the wing-tail interference has significant effects on static stability of tail-controlled missile.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.49 no.2
• /
• pp.85-93
• /
• 2021

In this paper, the aerodynamic characteristics of general tail controlled missile were predicted and corrected the result using semi-empirical analysis tool. The cause of the error was confirmed by comparing the aerodynamic characteristics prediction result of the semi-empirical analysis tool with the wind tunnel test result, and the main error factor of the semi-empirical analysis tool was the interference component between the main wing and the tail wing. The semi-empirical analysis results were corrected using the wind tunnel test results and the computational analysis results, and it was confirmed that the corrected data agrees well with the wind tunnel test results. Through this study, it was confirmed that the wing-tail interference component correction is needed when predicting the aerodynamic characteristics of a general tail controlled missile using a semi-empirical analysis tool.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.41 no.3
• /
• pp.211-219
• /
• 2017

In this study, we performed numerical simulations on a circulating air classifier using a commercial computational fluid dynamics program. The variations in the grade efficiency, the cut-size and the cut-sharpness were calculated and discussed. By controlling the rotating speed of the main fan, the cut-size could be rapidly increased. However the linearity of the cut-size variation with respect to the main fan speed was not sufficient for application to contaminated soil classification processes. On the other hand, by varying the rotating speed of the classifying fan, the cut-size gradually decreased and could be precisely adjusted. Using both the main fan and the classifying fan, we could achieve larger cut-sharpness values and better classifying performances.

• 지반과기술
• /
• v.2 no.1
• /
• pp.65-67
• /
• 2005

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.8
• /
• pp.758-766
• /
• 2010

The design procedure of Solar Power UAVs is complicated because the configuration and required power for flight must be considered simultaneously as the supplied power is influenced by the wing area. In order to minimize trial and error for the Solar Power UAVs design, a systematic sizing method is proposed which can be used to determine whether a Solar Power UAV is feasible for a given mission, and to derive preliminary dimensional specification of it. The sizing procedure begins with initially assumed wing area because the power, lift, and drag of the wing are directly proportional to it. The assumed wing area and mission requirements are then used to determine step by step the airfoil specifications including lift coefficient and drag coefficient, weight, required power, and wing area. This procedure is iterated for each newly assumed wing area until the error between the assumed wing area and calculated wing area becomes significantly small enough. This sizing methodology was applied to previously developed Solar Power UAVs for validation purposes, resulting in good agreement. The methodology was also applied to determine the dimensions and specifications of the Solar Power High-Altitude Long-Endurance UAV.

• Korean journal of applied entomology
• /
• v.52 no.4
• /
• pp.311-314
• /
• 2013

Blepharhymenus koreanus Pa$\acute{s}$nik and Tachyusa wei Pace are recorded for the first time in South Korea. Habitus photographs, redescriptions and illustrations of diagnostic characters are provided.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.11
• /
• pp.1028-1035
• /
• 2007

this study, forced vibration analysis was performed on the composite main wing structure of a small scale WIG craft which is equipped two-stroke pusher type reciprocating engine. The structural vibration analysis based on the finite element method was performed using a commercial FEM code, MSC/NASTRAN. Excitations for the frequency response analysis were assumed as the H-mode(horizontal mode), the V-mode(vertical mode) and the X-mode(twisted mode) which are typical main vibration modes of engine. And excitations for the transient response analysis were assumed as the L-mode(longitudinal mode) with the oscillating propeller thrust which occurs.

• Journal of KSNVE
• /
• v.1 no.2
• /
• pp.102-106
• /
• 1991

최근의 사회적 경제적인 급속한 발전에 따라 환경 소음에 대한 사람들의 관심도가 점차 증가되고 있다. 이로 인하여 사람들이 항상 접촉하게 되는 가전 제품 에 대한 소비자의 욕수도 제품의 성능적인면도 물론이지만 소음진동 및 디자인에 대하여도 지대한 관심이 모아지고 있다. 가전 제품에 있어서 주된 소음원은 홴 및 압축기 덮개의 진동등으로 파악할 수 있다. 특히, 홴은 냉각용, 송풍용으로서 거의 모든 가전제품에 쓰여지고 있다. 냉각용으로 사용되는 형식은 주로 축류 홴이다. 축류 홴은 다른 종류보다 소음이 크기 때문에, 저소음 축류 홴의 BPF(Blade Passing Frequency; 날개 통과 주파수)가 갖는 소음 특성을 연구하여야 한다. 이를 위해 축류 홴의 날개 갯수를 조절하면 설치된 통내에서의 BPF가 어떠한 형태로 변화하는가를 알아보고, 이에 따른 저소음화 대책을 검토하고자 한다. 홴은 그 덮개에 대하여 유량 및 소음에 관한 최적의 위치가 존재하는데, 문이 잠겨 있을 때에는 그 소음 레벨의 편차가 몹시 크게 된다. 한편 날개 갯수, 모터의 회전속도 및 통의 전달 함수 등을 감안하여 날개 통과 주파수(BPF)를 조정하면, 각종 가전 제품의 홴에 의한 방사를 저감시킬수 있다.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.10
• /
• pp.7-15
• /
• 2006

The effects of strake incidence-angle on the vortex characteristics and the wing-surface pressure distribution for a double-delta wing with strake were investigated experimentally. The strake incidence-angle of negative sign(strake is pitched down from the main-wing upper-surface) increased the suction pressure of the wing-upper surface, which was the same effect of increase of angle of attack. This change of the suction pressure was caused by the closer movement of the vortex cores to the wing upper surface rather than the increase of the vortex strength.

• The Korean Journal of Zoology
• /
• v.26 no.1
• /
• pp.29-40
• /
• 1983

The differences in the electron microscopic fine structures of the wing imaginal discs of the vestigial (vg), wing mutant and wild type of Drosophila melanogaster were investigated. The materials used in this study were collected at ten hours intervals from the late third instar larvae of the both stocks. The fine structural changes during differentiation were as follows: 1. In wild type lipid droplets were coalesced and converted to glycogen, while no changes were observed in the mutatn vestigial. 2. Degeneration of the cells by phagocytosis were observed not only from the mutatn vestigial, but from the wild type. However, degenerative feature of the wild type was poor. 3. Dented structures of tracheole showed little differences between wild type and the mutant vestigial. But the tracheole diameter of the wild type became wider in the course of differentiation, while the mutant vestigial narrow. Although mutant vestigial develops normally during early embryogenesis, the late third instar larvae shows defficiency in gluconeogenesis, converting fatty acid to glycogen. This, together with the predominant cell degeneration by phagocytosis and poorly developed tracheole, seems to effect on the expression of the vestigial phenotype.