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노현영(Roh, Hyun-Young),유홍희(Yoo, Hong-Hee) 한국소음진동공학회 2007 한국소음진동공학회 논문집 Vol.17 No.6
This paper presents a friction model to realize self-excited vibration of multi-body systems. The friction coefficient is modeled with a spline function in most commercial codes. Even if such a function resolves the problem of discontinuity in friction force, it cannot realize self-excited vibration phenomena. Furthermore, as the relative velocity approaches zero, the friction coefficient approaches zero with the conventional model. So, slip occurs when small force is applied to the system. To avoid these problems a new friction model is proposed in this study. With the new friction model, the self-excited vibration can be realized since the friction coefficient changes with the relative velocity. Furthermore, the slip phenomena could be reduced significantly with the proposed model.
다물체 동역학 해석을 위한 마찰 접촉 모델링에 대한 연구
노현영(Hyun Young Roh),김범석(Bum Suk Kim),유홍희(Hong Hee Yoo) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
This paper presents the method to remove the slip problem of the friction contact modeling employed in most of multibody dynamic analysis programs. Even if contact occurs between two rigid bodies with no slip condition, most of contact algorithms developed so far provide the results of low speed slip motion. The friction coefficient is defined as a spline function of relative velocities in most commercial codes. Such a function resolved the problem of the discontinuity in friction force. However, when the relative velocity approaches zero, friction coefficient approaches zero too. So, slip occurs when small force is applied. This problem of low speed slip is resolved in this study with a new modeling method.
기하학적 형상에 의한 Mixing Element의 유동 혼합 특성
김필환(Pil-Hwan Kim),이용훈(Yong-Hun Lee),최두열(Du-Yeol Choi),김경석(Kyeong-Seok Kim),정효민(Hyo-Min Jeong),정한식(Han-Shik Chung) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-
Static mixers are a series of geometric mixing elements fixed within a pipe, which use the energy of the flow stream to create mixing between two or more fluids. So, this study was carried out to know the pressure drop in the helical type static mixer numerically for a range of Reynolds number as 100 ~ 1000, and the analysis results will show that the pressure drop correlation in a helical static mixer with Reynolds number.
차량안정성제어시스템(ESC)장착 차량의 조종안정성 평가방법 표준화에 관한 연구
이명수(Myungsu Lee),민경찬(Kyongchan Min),남궁석완(Sukwan Namkung),권해붕(Haeboung Kwon),최선모(Sunmo Choi) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
As the ESC become more affordable, the research regarding the performance appraisal method of the ESC is actively advanced. The research was spearheaded by the UN/ECE/WP29 and ISO. Specially, the United States established a ESC efficiency requirements with the FMVSS. And the UN/ECE/WP29 is in the process of propelling the Global Technical Regulation establishment of the ESC. Republic of Korea is the member of U.N. and ISO that participates in the wide range of international meetings. This paper describes vehicle-test results for establishment of the Korean Standards, carrying out actual test to verify the determination of dwell time, Max. steering wheel angle input and the proposed measuring method of lateral displacement and to propose the additional evaluation criteria of ESC efficiency.
제동시 발생하는 리어 드럼브레이크 grunt (stick-slip) noise 개선
홍일민(Ilmin Hong),장명훈(Myunghoon Jang),김선호(Sunho Kim),최홍석(Hongseok Choi) 한국소음진동공학회 2012 한국소음진동공학회 학술대회논문집 Vol.2012 No.10
Grunt (Stick-slip) noise happens between rear lining and drum on braking condition while vehicle is returning to steady position after nose-dive. The study presents a new testing and analysis methods for improving brake grunt noise on vehicle. Grunt noise is called a kind of stick slip noise with below 1kHz frequency that is caused by the surfaces alternating between sticking to each other and sliding over each other with a corresponding change in friction force. This noise is typically come from that the static friction coefficient of surfaces is much higher than the kinetic friction coefficient. For the identification of the excitation mechanism and improvement of grunt noise, it is necessary to study variable parameters of rear drum brake systems on vehicle and to implement CAE analysis with stick slip model of drum brake. The aim of this study has been to find solution parameters throughout test result on vehicle and dynamo test. As a result of this study, it is generated from stick slip between rear lining and rear drum and it can be solved to reduce contact angle of lining with asymmetric and is effected not only brake drum strength but also rear brake size and brake factor.