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전진비행시 복합재료 헬리콥터 회전익의 공탄성에 대한 파라미터 연구
정성남,김경남,김승조 한국소음진동공학회 1997 소음 진동 Vol.7 No.5
The finite element analyses of a composite hingeless rotor blade in forward flight have been performed to investigate the influence of blade design parameters on the blade stability. The blade structure is represented by a single cell composite box-beam and its nonclassical effects such as transverse shear and torsion-related warping are considered. The nonlinear periodic differential equations of motion are obtained by moderate deflection beam theory and finite element method based on Hamilton principle. Aerodynamic forces are calculated using the quasi-steady strip theiry with compressibility and reverse flow effects. The coupling effects between the rotor blade and the fuselage are included in a free flight propulsive trim analysis. Damping values are calculated by using the Floquet transition matrix theory from the linearized equations perturbed at equilibrium position of the blade. The aeroelastic results were compared with an alternative analytic approch, and they showed good correlation with each other. Some parametric investigations for the helicopter design variables, such as pretwist and precone angles are carried out to know the aeroelastic behavior of the rotor.
정성남 원광대학교 2005 論文集 Vol.34 No.-
The symbol of circle reinforces the belief that it is the most fundamental one out of all types of symbols. Circle in Won-Buddhism represents the ultimate, one, absolute, and cosmic truth. First, it symbolizes that the one truth is empty: An important meaning represented in the archtype of ○ is that the truth is emptiness. The emptiness refers to impersonal and no-form with natural properties. The fundamental base of the universe is a true emptiness. Second, it symbolizes a perfect and impartial truth: Another meaning that the archetype involves is that the fundamental truth is to be perfect and impartial. It refers to Buddha(the enlightened)'s mind, nature of all living beings, and origin of the universe which are perfect and impartial. Third, it symbolizes the truth which is continuously changeable and also constant all the time: The circle, Ilwonsang, is a religious symbol newly born in the modern historical situation in which the traditional religious symbols were in a trial. It is the future oriented religious symbol which involves a historical mission for playing a role as a new spiritual source for the mankind and a guider of life within itself. And this symbol gradually appears on the historical horizon. In this aspect, the symbol of Ilwonsang as a new religious symbol for the new era has some meanings such as melting mankind history and tradition into this symbol, letting religion and science go side by side, and suggesting it as an object for belief and a standard for practice.
Structural Property Measurement of HART II Blades
정성남,유영현 한국항공우주학회 2014 한국항공우주학회 학술발표회 논문집 Vol.2014 No.4
최신의 측정기법을 적용하여 HART II 블레이드에 대한 구조 물성치를 계측하였다. 측정을 위해 2001 년 풍동시험에 이용했던 당초 블레이드 원형을 포함하여 몇 개의 블레이드를 동원하였으며, 굽힘 및 비틀림 강성계수, 단면의 기하학적 중심치, 그리고 질량 및 관성치를 계측하였다. 기계적 측정이 어려운 물성치에 대해서는 X-선 컴퓨터 단층촬영 기법을 통해 얻은 단면의 디지털 화상정보를 이용하여 2 차원 유한요소해석을 통해 물성값을 획득하였다. 시험을 통해서 얻은 물성치를 기존의 HART II 데이터와 비교했으며, 기존의 해석적 방법에 의해 도출된 단면계수들은 실측치에 비해 다소 과대하게 예측하고 있음을 확인하였다. The structural properties of Higher-harmonic Aeroacoustic Rotor Test (HART) II blades are determined using the stateof-the-art test techniques. The measurement includes bending and torsion stiffnesses, section geometric offsets, and mass and inertia properties. Several HART II blades including the original instrumented blade used for the wind tunnel test campaign in 2001 are employed for the activity. A finite element based cross-section analysis combined with the xray computer tomography technique is used for cases where no mechanical measurement is attempted. The resulting structural properties are correlated against the earlier estimated ones. It is found that the earlier properties overestimate the section values substantially.