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부분적으로 물에 잠겨있는 Shell 구조물의 바닥면과 거리변화에 따른 진동해석 연구
구재량(Koo, Jae-R.),곽문규(Kwak, Moon-K.),송오섭(Song, Oh-S.),배춘희(Bae, Chun-H.) 한국소음진동공학회 2011 한국소음진동공학회 논문집 Vol.21 No.10
The free flexural vibration of a hanged clamped-free cylindrical shell partially submerged in water with gap from bottom is investigated. The fluid is assumed to be inviscid and irrotational. The cylindrical shell is modeled by using the Rayleigh-Ritz method based on the Sanders shell theory. The kinetic energy of the fluid is derived by solving the boundary-value problem related to the fluid motion. The natural vibration characteristics of the partially submerged cylindrical shell are discussed with respect to the added virtual mass approach. In this study, experiments were carried out to confirm theoretical results. It was found that theoretical prediction is in good agreement with experimental results.
신지환(Ji-Hwan Shin),곽문규(Moon K. Kwak),구재량(Jae R. Koo) 한국소음진동공학회 2016 한국소음진동공학회 학술대회논문집 Vol.2016 No.4
본 연구에서는 2차원 단순 모델인 1자유도 및 2자유도 갤러핑 모델을 구성하고, 운동 방정식을 구성한 뒤 시뮬레이션을 수행하였다. 먼저 1자유도 스프링 질량 시스템을 구성하여 상하로만 변위가 생긴다는 가정 하에 시뮬레이션을 수행하였다. 이 후 2자유도 스프링 질량 시스템을 구성한 다음, 상·하 및 좌·우로 움직인다고 가정하여 변위를 계산 하였다. 단면 형상은 타원으로 가정하였고, 이 때의 공기력 데이터를 수치 계산에 적용하였다. 일정한 바람이 불어오고 특정 입사각에서 타원형의 물체는 불안정성을 가지게 된다. 시뮬레이션 결과는 공기력 데이터를 수집하기 위해 수행한 실험 결과와 유사함을 확인하여 본 연구의 갤러핑 시뮬레이션 결과의 타당성을 입증하였다.
신지환(Ji-Hwan Shin),곽문규(Moon K. Kwak),김승기(Seung-Ki Kim),구재량(Jae R. Koo) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.10
This paper is concerned with the dynamic modeling single and bundled transmission line. To cope with bundled transmission line, the spacer was modelled by a spring element. To this end, the kinetic and potential energies of a uniform wire are derived. The equations of motion are expressed in matrix form by using the Assumed Mode Method and Lagrange equation. It is suitable for numerical simulations. The algorithm for galloping simulations under the wind load is developed. By concerning the cross-section for snow accretion on the cable, total EOM which is considered aerodynamic coefficients is derived. The 2<SUP>nd</SUP> order differential equation for EOM can be transferred to 1<SUP>st</SUP> order state-space equation. And using the Matlab function ‘ode45’, a results for numerical calculations of galloping are obtained.
신지환(Ji Hwan Shin),곽문규(Moon K. Kwak),구재량(Jae R. Koo) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.4
This paper is concerned with the dynamic modeling and experiment of bundled transmission line and vibration experiment. To this end, the kinetic and potential energies of a uniform wire are derived. The equation of motion suitable for numerical simulations are derived using the assumed mode method and Lagrange equation. To cope with bundled transmission line, the spacer was modelled by a spring element. Natural frequencies were determined experimentally by image processing of video data. I t was found that experimental natural frequencies are in good agreement with theoretical natural frequencies. It was also found both theoretically and experimentally that the number of spacers does not change the natural frequencies.