• 한국공작기계학회논문집
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• 제14권3호
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• pp.122-127
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• 2005

The styling of automobile wheels and their effect on vehicle appearance has increased in importance in recent years. The wheel designer has been given the task of insuring that a wheel design meets its engineering objectives without affecting the styling theme. The wheel and tire system is considered as a vehicle component whose dynamic modal information of the tire/wheel system are employed in the modal synthesis model of the vehicle. The vibration characteristics of a automobile wheel play an important role to judge a ride comfort and quality for a automobile. In this paper, the vibration characteristics of a Al-alloy and steel wheel for automobile are studied. Natural frequency, damping and mode shape are determined experimentally by frequency response function method. Results show that wheel material property, size and design are parameter for shift of natural frequency and damping.

• Journal of Advanced Marine Engineering and Technology
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• 제28권3호
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• pp.434-440
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• 2004

The electro-rheological fluids for semi-active suspension system are a class of colloidal dispersion which exhibit large reversible changes in their rheological behavior when they are subjected to external electrical fields. This paper presents Bingham properties of ER fluids subjected to temperature variations. In addition, an appropriate size of the ER damper for a passenger car is proposed to investigate the effects of Bingham characteristics on the damping performance. The filed-dependent damping forces are evaluated according to the temperature variation and sedimentation ratio.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.623-628
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• 2001

The styling of passenger car wheels and their effect on vehicle appearance has increased in importance in recent years. The wheel designer has been given the task of insuring that a wheel design meets its engineering objectives without affecting the styling theme. The wheel and tire system is considered as a vehicle component whose dynamic modal information of the tire/wheel system are employed in the modal synthesis model of the vehicle. The Vibration characteristics of a passenger car wheel play an important role to judge a ride comfortability and quality for a passenger car. In this paper, the vibration characteristics of a AI-alloy and steel wheel for passenger car are studied. Natural frequency, damping and mode shape are determined experimentally by frequency response function method. Results show that wheel material property, size and design are parameter for shift of natural frequency and damping.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.543-546
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• 1997

The purpose of this study is to investigate the ERSU(Electr0-Rheological Suspension IJnit) and some progress of damping force characteristic of a ERSU. This paper describes overall construction of th'e system design and the manufacturing of ERSU. A model of the ERSU is made by using electric field dependent on Bingham properities of ER fluid. In this paper. the ERSU is designed and manufactured for a light ground tracked vehicle. From the results, it is shown that the damping performance of ERSLJ is better than that of a passive suspension unit. This experimental study might be very useful for the simulat~on and the design of semi-active suspension units.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.101-108
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• 2008

The dynamic behavior of railway bridges originates from dynamic properties of various spans and structural types. As a result, the exact estimation of dynamic properties of the railway bridge can produce the exact estimations of dynamic performances of the railway bridge. The damping ratio affects the dynamic reponses of the railway bridge in the vicinity of the critical speed seriously. Eurocode, National Annex of each European country and Japan have their own specification for the damping ratio for the estimation of dynamic performance of railway bridges. In our case, the specification for Honam high speed railways follows the Eurocode. In the present study, for the verification and regulation of the damping ratio and investigation of various dynamic properties, modal tests of various structural types are performed. In addition, for the investigation of effects of track structures on the dynamic property of the bridge, ballast track and concrete track are installed and tested.

• 한국정밀공학회지
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• 제17권8호
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• pp.41-45
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• 2000

This paper provides a new concept of the controllable micro damper using MR(Magneto Rheological)fluids. The damper is composed of four layers which are fabricated by wet etching. The Process of the fabrication is explained and the change of damping property is experimentally shown. Since the damping force is controllable by the applied magnetic field the vibration can be effectively absorbed.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.471-478
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• 2006

This paper presents the results of experimental studies of the mechanical characteristics of the Coil Spring and Viscous Damper system. The Coil Spring and Viscous Damper systems were selected for the isolation of Emergency Diesel Generator (EDG) which is located in Nuclear Power Plant (NPP). The Coil Spring and Viscous Damper systems were developed for, the operating vibration isolation and seismic isolation for scaled Model EDG System. The damping properties of the viscous damper changes as the variation of velocity. As a results, nonlinear damping characteristics of viscous damper system were evaluated.

• 폴리머
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• 제31권4호
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• pp.289-296
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• 2007

셀 구조는 유사하나 흡음성능에서 차이가 있는 시편을 사용하여 폴리우레탄 폼의 흡음성능을 예측할 수 있는 인자들을 FT-IR, 소각 X-선 산란(SAXS)과 dynamic mechanical thermal analyzer(DMTA)로 조사하였다. 그 결과, 전이영역에서의 damping 특성이 흡음성능과 가장 밀접한 관계가 있음을 알 수 있었다. 최근 개발된 low monol 폴리올(LMP)을 흡음용 폴리우레탄 폼에 적용할 수 있는가를 검토하기 위하여 LMP와 산화프로필렌계 폴리올(PPG)을 기본으로 한 폴리우레탄을 용액중합법으로 제조하고, 이들의 내부구조와 물리적 성질을 상호 비교하였다. Monol 성분을 다량 포함하는 PPG는 LMP에 비하여 분자 유동성이 커서 보다 발달된 상분리 구조를 보여주었다. 그러나 monol 성분에 의해 고분자량으로 성장하지 못한 분자사슬의 비효율적인 damping 거동으로 인하여 LMP의 경우가 PPG에 비하여 전이영역이 넓고, damping 양도 훨씬 더 컸다.

• 한국재료학회지
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• 제8권10호
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• pp.905-911
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• 1998

감쇠란 주기적인 변형하에 에너지를 소산시킬 수 있는 시스템이나 재료의성질을 말하며, 이로서 공진에서 진폭을 감소시키며 아울러 전달하는 파의 빠른 감소를 유발한다. 이것은 진동을 일으키는 응력을 감소시키게 되는데 결국은 피고 수명을 연장시키는 결과를 가져오게 된다. 본 연구에서는 적층된 복합재료의 내부감쇠와 복소탄성 계수를 실험적으로 측정하였다. 실험은 충격 기법을 사용하였으며 비교적 간단한 모델러서 외팔보의 휨진동을 측정하였다. 복소 탄성계수는 공진법을 이용하여 공진주파수를 측정 storage modulus를 계산하고 이를 통해 loss modulus를 구한 다음 계산하였고, 내부감쇠는 bandwidth technique과 전달함수의 실부부분 이용방법에 의해 각각 구하였다.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.164-174
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• 1996

This paper presents control and response characteristics of a continuously variable ER(electrorheological) damper for small-sized vehicles. The ER damper is devised and its governing equation of motion is derived from the bond graph model. The field-dependent yield shear stresses are distilled from experimental investigation on the Bingham property of the ER fluid. The distilled data are incorporated into the governing system model and, on the basis of this model, an appropriate size of the ER damper is manufactured. After evaluating the field-dependent damping performance of the proposed ER damper, the skyhook control algorithm is formulated to achieve desired level of the damping force. The controller is then experimentally implemented and control characteristics of the ER damper are presented in order to demonstrate superior controllability of the damping force. In addition, response characteristics of the damping force with respect to the electric field with fast on-off frequency are provided to show the feasibility of practical application.