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이성엽(Seong-Yeop Lee),최주호(Joo-Ho Choi),강진혁(Jin-Hyuk Gang) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
In this study, complex eigenvalue analysis is conducted considering frictional heat to predict the squeal noise of the brake system with more accuracy. The finite element analysis software ABAQUS is used to calculate the frictional heat generation and dynamic instability. Modal analyses and experimental modal tests of the brake disc components are performed to ensure the validity of the finite element model. As opposed to the previous studies that employed uniform temperatures for simplicity, the analytical temperature distribution is obtained by using a thermal-structure coupled field analysis in this study. The distribution is compared with the real measurements of the disc surface temperature during the squeal noise test. Finally, the effect of applying the temperature distribution is examined by comparing with the results by assuming the uniform temperatures.
전인식(Chun, In-Sik),이성엽(Lee, Seong-Yeop),박경수(Park, Kyung-Soo),안동근(An, Dong-Keun) 한국해안해양공학회 2007 한국해안해양공학회 논문집 Vol.19 No.3
흐름이 연직유공벽을 통과할 때 발생하는 수두손실을 수치해석과 수리실험을 통하여 고찰하였다. 수치 해석에 대해서는 유공벽 전 후의 검사체적에 연속방정식, 모멘텀 방정식, 그리고 에너지 방정식을 적용하였으며 주어진 하류 쪽 수심과 유속에 대하여 상류 쪽 수심 및 유공벽 수두손실을 계산할 수 있는 무차원 관계식을 유도 하였다. 수리실험은 단일유공판과 삼중유공판에 대하여 각각 수행하였다. 단일유공판에 대한 계산결과와 실험결과를 비교하여 유공부 오리피스에서 연직 선형 제트류의 수축계수가 개구율뿐만 아니라 하류 쪽 Froude 수에도 의존함을 밝혔으며, 실험결과에 근거하여 수두손실을 계산하기 위한 실험식을 제시하였다. 단일유공판의 실험식을 삼중유공판에 대하여 하류에서 상류 쪽으로 축차적으로 적용한 결과, 예측치와 실험결과가 대체적으로 잘 일치함을 확인하였다. A numerical analysis and hydraulic experiments were undertaken to investigate the head loss occurring when a flow passes through vertical perforated walls. The numerical analysis applied continuity, momentum and energy equations to the control volumes that were set near the perforated wall. Non-dimensional equations were then derived to calculate both upstream depth and head loss for the given values of downstream depth and velocity. The hydraulic experiments were performed with several single and triple perforated plates varying their opening ratios and intervals. The numerical results with the single plates were compared with the experimental results, and it was shown that the contraction coefficient of the vertical line jet formed after the perforated plates relies on downstream Froude number as well as opening ratio. Based on the experimental results, empirical formulas were formulated. Finally, the formulas were applied to the triple plates sequentially from downstream side to upstream side, and it was found that in general the predicted values nicely agreed with the experimental results.
S&R 예방을 위한 확률기반 유한요소해석 프로그램 개발
최주호(Joo-Ho Choi),박성훈(Sung-Hoon Park),최재민(Jae-Min Choi),이제성(Je-Seong Lee),이성엽(Seong-Yeop Lee) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.4
BSR(Buzz, squeak and rattle) is the key factor that makes decision of quality of product, which should be eliminated and various efforts for that have been done by developer. Especially, unlike the conventional methods that are done after production such as adding tapes or sponges, some recent techniques have been focused on predicting BSR at design stage using finite element method. In this study, methods to detect rattle based on the frequency response analysis(FRA) are introduced, which are applied on simple structure composed of two cantilever beams and results are compared with that from simulation. In addition, probabilistic approaches are developed to consider the variation that parameters used for FRA have. More efficient probabilistic analysis techniques including response surface and sensitivity analysis are used to reduce computational costs, which are carried out on numerical example to determine their validity by comparing with Monte-Carlo simulation. Program to conduct procedure of probabilistic analysis is established using MATLAB, which can be used for NASTRAN limitedly.