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부분 탄성기초를 갖고 종동력을 받는 보의 플러터 불안정
류봉조,류시웅,조창기,이종원 한밭대학교 생산융합기술연구소 2004 생산기반기술연구소 논문집 Vol.4 No.1
In this paper, the dynamic stability of a cantilevered beam partially attached to elastic foundations and subjected to a follower force is studied. The beam has a concentrated mass at an arbitrary position on it. Governing equations are derived by extended Hamilton's principle and the finite element formulations are applied to obtain discretized equations. The influence of some parameters, such as the elastic foundation parameter, the position of partial elastic foundations, mass ratios and rotary inertia of the concentrated mass on the critical flutter load is investigated. Finally, the optimal attachment ratio of partial elastic foundation which maximizes the critical flutter load is found.
유체유동에 의한 유연한 파이프의 불안정과 진동억제에 미치는 부가질량의 영향
류봉조,정승호,이종원 한국소음진동공학회 2000 소음 진동 Vol.10 No.2
The paper deals with vibration suppression and dynamic stability of a vertical cantilevered pipe conveying an internal flowing fluid and having an attached mass. Real pipe systems may have some valves or mechanical attached parts, which can be regarded as attached lumped masses. The effect of attached mass on the dynamic stability of a cantilevered pipe conveying fluid is investigated for different locations and magnitudes of the attached mass. The flow rate was controlled through motor pump output and measured by a flow meter. Experimental resutls in the vicinity of flutter fluid velocity were compared with theoretical predictions. It has been found that the experimental results are in substantial agreement with the theoretical predictions. Finally, in order to suppress the vibration of the pipe subjected to a disturbance, and control technique using an internal flowing fluid is introduced.
화재에 대한 Extra-dosed교 케이블의 안전성 평가
류봉조,송용선,박원태,Rhu. Bong-Jo,Song. Young-Sun,Park. Weon-Tae 한국방재학회 2008 한국방재학회논문집 Vol.8 No.5
최근 국내에서 케이블을 이용한 Extradosed 교 형식의 대교들이 건설되고 있다. 이러한 교량에서 자동차 충돌등으로 인한 화재에 의해 교량이 손상을 입는 사고가 발생되고 있어 화재에 대한 안정성해석이 필요하다. 본 연구에서는 케이블 교량형식 중 최근 국내에서 사용빈도가 높은 Extradosed 교 형식을 해석모델로 하였으며, 상용소프트웨어인 Solid Works 2007을 사용하여 모델링하고, COSMOS FloWorks 2007소프트웨어에 의한 열전달 해석 및 열응력 해석을 통하여 교량위 화재 발생시 와이어, 사재방재 파이프 및 그 주변에 대한 열유동 해석 및 사재방재 케이블의 안전을 검토하였다. 열원의 온도가 일정한 경우에 대해 다음 3개의 중요변수를 해석변수로 사용하였다. : (1)방호책과 열원사이의 거리, (2)풍속, (3) 스테인레스 강관의 끝단의 높이. Extra dosed bridge among the Cabled-stayed bridges have been increasingly built in korea in recently. But such bridges were often damaged by fire due to car collison. In this study Extra dosed bridges among the cabled-supported bridges are selected to analysis model frequently to be designed and/or constructed in recent and furture in this study. COSMOS FloWorks 2007 software are used for Heat Transfer Analysis and Thermal Stress Analysis. The safety of wire, HDPE pipe and stainless steel pipe are investigated. In the case of the constant of the temperature of the heat source, the significant three variables for the analysis are selected for study : (1) the distance between the fire-proof bulk head and the heat source, (2) wind velocity, (3) the height of the end of Stainless steel pipe.