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유연체 로터-커플링-블레이드 시스템의 로터 축과 블레이드의 연성 진동에 관한 연구
오병영(Oh, Byung-Young),이선숙(Lee, Sun-Sook),윤형원(Yoon, Hyungwon),차석주(Cha, Seog-Ju),나성수(Na, Sungsoo) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.9
In this paper, a dynamic model for the rotor shaft-coupling-blade system was developed. The blades are attached to a disk and driven by an electric motor shaft which is flexible in torsion. We assumed that the shaft torsional flexibility was lumped in the flexible coupling which is usually adopted in rotor systems. The Lagrangian approach with the small deformation theory for both blade-bending and shaft-torsional deformations was employed for developing the equation of the motion. The Assumed Modes Method was used for estimating the blade transverse deflection. The numerical results highlight the effects of both structural damping of the system and the torsional stiffness of the flexible coupling to the dynamic response of the blade. The results showed strong coupling between the blade bending and shaft torsional vibrations in the form of inertial nonlinearity, stiffness hardening and softening.
고온에서 외부 가진력을 받는 회전하는 경사기능 박판 블레이드의 동적응답 해석
오병영(B.Y.Oh),나성수(Sungsoo Na) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
This paper is dedicated to the thermoelastic modeling and dynamic response of the rotating blades made of functionally graded ceramic-metal based materials. The blades modeled as non-uniform thin walled beams fixed at the hub with various selected values of setting angles and pre-twisted angles. In this study, the blade is rotating with a constant angular velocity and exposed to a steady temperature field as well as external excitation. Moreover, the effect of the temperature gradient through the blade thickness is considered. Material properties are graded in the thickness direction of the blade according to the volume fraction power law distribution. The numerical results highlight the effects of the volume fraction, temperature gradient, taper ratio, setting angle and pre-twisted angle on the dynamic response of bending-bending coupled beam characteristics are provided for the case of a biconvex cross section and pertinent conclusions are outlined.
고강도 콘크리트용 시멘트계 메트릭스의 레올로지 성질 및 합리적 유동성 평가에 관한 연구
이건철,조병영,오동욱,Lee, Gun-Cheol,Cho, Byoung-Young,Oh, Dong-Uk 대한건축학회 2012 대한건축학회논문집 Vol.28 No.1
In this study, both rheological aspect for fluidity and correlation for fluidity evaluation methods of cement paste and mortar for high strength concrete mix are considered. Effects of the fiber and correlation of fluidity evaluation methods for cement paste and mortar of each mix in four high strength concrete mix of 40~100 MPa used on the site are reviewed. As a result, cementitious matrix appeared high fluidity, but fluidity in case of adding fiber into plain mix has been decreased because of high viscosity and networking effect of fiber. In addition, the relation of between each fluidity evaluation method and rheological parameters has rather lower interrelationship in case of slump flow, but it showed higher interrelationship with between both 500mm arrival time of L flow test and funneling time and rheology integer. Therefore, in case of high fluidity concrete such as high strength concrete, The physical evaluation including shear-strain rate in addition to fluidity evaluation such as flow is important.
외부환경 변화에 따른 단열소재 이용 시멘트 압출패널의 특성 검토
오동욱(Oh Dong-Uk),이건철(Lee Gun-Cheol),조병영(Cho Byoung-Young) 대한건축학회 2012 大韓建築學會論文集 : 構造系 Vol.28 No.5
The purpose of this study was to analyze the weatherproof for insulation, warpage and unification characteristics of extrusion cement panel(ECP) according to the variation of external environment. Result to analyze mechanical properties of ECP in a preparatory experiment decided 50% about replacement ratio of insulation materials for fine aggregate as optimum mix of ECP. The weatherproof of ECP using 50% insulation materials were as follows; In insulation characteristics, the thermal conductivity after freezing and thawing test was higher than that after change of temperature and humidity. In warpage characteristics, bending strength and deflection were examined. V and PL with low density had low bending strength after freezing and thawing. The deflection of PL in bowing test was higher than another because hollow bead as insulation materials. Finally, unification characteristics of ECP followed from high quality as low length variations and good bond strength.