• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.780-787
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• 2013

Virtual Seat Method (VSM) is used in this study for a combined evaluation method (objective & subjective) to determine comfort value of passenger vehicle seat in terms of idle vibration. In the study, a process for applying VSM divided into two stages is established. Two kinds of seat mounting passenger vehicle and six subjects are employed to compare the comfort value obtained by VSM method and by SEAT value. As a conclusion, the results by the two methods were well consistent so that VSM is verified as a method to measure ride comfort of seat in terms of idle vibration at passenger vehicle.

• 한국철도학회논문집
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• 제14권6호
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• pp.495-500
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• 2011

철도차량의 승차감은 승객이 느끼는 감정이므로 물리적인 진동의 크기뿐만 아니라 인간의 감응도(느낌)도 고려하여야 하며, 이러한 진동에 대한 인간의 감응도를 나타낸 것이 주파수 보정곡선이다. 주파수 보정곡선은 라플라스 변환형태의 전달함수이기 때문에 이 전달함수를 직접 사용하여 시간 영역에서의 승차감의 평가가 불가능하다. 이를 해결하기 위해서 본 논문에서는 라플라스 변환형태의 전달함수를 시간 영역에서 사용할 수 있는 전달함수로 변환하는 방법을 제시하고 다양한 예제를 통해 이 방법에 대한 타당성을 입증하였다.

• 한국소음진동공학회논문집
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• 제23권5호
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• pp.463-471
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• 2013

This paper presents design and control of electronic control suspension(ECS) equipped with controllable magnetorheological(MR) damper for passenger vehicle. In order to achieve this goal, a cylindrical type MR fluid damper that satisfies design specification of a middle-sized commercial passenger vehicle is proposed. After manufacturing the MR damper with design parameters, their field-dependent damping forces are experimentally evaluated and compared with those of a conventional damper. A quarter-vehicle MR ECS system consisting of sprung mass, spring, tire, controller and the MR damper is established in order to investigate the ride comfort performances. On the basis of the governing equation of motion of the suspension system, five control strategies(soft, hard, comfort, sport and optimal mode) are formulated. The proposed control strategies are then experimentally realized with the quarter-vehicle MR ECS system. Control performances such as vertical acceleration of the car body and tire deflection are evaluated in frequency domains on random road condition. In addition, performance comparison of WRMS(weighted root mean square) of the quarter-vehicle MR ECS system on random road are undertaken in order to investigate ride comfort characteristics.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.272-277
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• 2007

Generally railway vehicle runs on the rail with endless interaction between wheel and rail. Irregularity of rail causes the periodic motion of the vehicle. In association with this motion, the design of vehicle would be carried out in order to avoid the resonance between car-body and bogie. It may be seen that the first vertical bending mode of car-body contributes considerably to the vertical ride comfort level. In this paper to know the effect of the car-body first vertical bending mode on vertical ride comfort, the mode has been considered with dynamic model. I-DEAS program was used to get the car-body first vertical bending mode and VAMPIRE program was used to analyze ride comfort index(Wz) with FE interface file.

• 한국자동차공학회논문집
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• 제24권1호
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• pp.59-66
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• 2016

The evaluations of ride comfort, handling, and steering feeling have been known as one of the dominant factors for vehicle performance assessment. However, those factors have not been analyzed in-depth in conjunction with general ride and handling design parameters. Thus, we have surveyed some previous studies dealing with subjective parameters and quantitative design parameters. We expect this paper provides some guidance to the future research on the field.

• International Journal of Safety
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• 제6권1호
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• pp.7-10
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• 2007

In this paper, we found that modification of the local flexibility (or local stiffness) of the 4 parts on which shock absorbers are mounted in the vehicle body has some influence the level of ride safety and comfort. Multi-body dynamic analysis considering the flexibility of the vehicle body is performed using MSC/ADAMS and MSC/NASTRAN. More concretely speaking, natural frequencies and mode shapes computed by MSC/NASTRAN are used as input data for multi-body dynamic analysis in MSC/ADAMS. It is confirmed that the ride comfort can be improved by appropriately changing the local stiffness of the vehicle body through several simulations using MSC/ADAMS.

• 대한인간공학회지
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• 제32권4호
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• pp.389-396
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• 2013

Objective: The ride qualities of the six passenger cars were evaluated in 4 subjects on the highway and uneven road. The relation between vibration with driving velocity and driving posture were also investigated separately. Background: Ride comfort plays an important role in the vehicle design. Vibration is the one of the principal components associated with ride comfort. Method: The acceleration of the foot, hip and back were measured using B&K accelerometers in this study. The velocity of the passenger cars was maintained at a constant speed of 80km/h on the highway and 40km/h on the uneven road. For evaluating the effects of driving velocity and driving posture on vehicle's vibration level, separate experiments were performed on the highway with 5 different vehicle speeds and 5 different backrest angles, respectively. Results: The overall ride value of the luxury car showed the best result while the smaller car showed the worst value on the highway. On the uneven road the overall ride value level was increased 75~98%. All the vehicles had the SEAT value less than 1. Faster the velocity lowers the SEAT value. The ride quality in terms of vibration gets worst when the backrest angle increased. Conclusion: The smaller car had a first mode at the higher frequency and showed higher vibration level. SEAT value was mostly affected by the seat property not by vehicle. We ranked the luxury car seat had a best vibration reduction quality than others based on SEAT values. When the driving velocity increased, the overall ride values were increased proportionally and the SEAT values were somewhat decreased. Application: Evaluation of whole-body vibration in the passenger car.

• 한국산학기술학회논문지
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• 제21권10호
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• pp.547-557
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• 2020

본 연구에서는 캡슐트레인의 승차감 향상을 위하여 캡슐트레인 모델 내의 현가장치에 감쇠 제어 장치를 적용하고 그 효과를 검토하였다. 캡슐트레인의 부상 방식으로 사용되는 초전도 유도 반발식 부상은 별도의 부상제어가 필요 없고 부상 공극이 큰 장점이 있다. 하지만, 본 부상 방식은 공극 변화량이 크고 외부로부터 유입되는 진동에 대한 작은 감쇠 특성으로 인해 캡슐트레인의 승차감을 저하시키는 단점이 있다. 본 연구에서는 캡슐트레인의 승차감 향상을 위해서 1차 및 2차 현가장치 내에 적용되는 감쇠 제어 장치를 고려하였다. 1차 현가장치에 적용되는 감쇠 제어 장치는 외란에 의해 발생하는 진동이 대차로 전달되는 것을 감소시키는 역할을 하고, 2차 현가장치 적용되는 감쇠 제어 장치는 대차의 진동이 차체로 전달되는 것을 감소시키는 역할을 한다. 감쇠 제어가 승차감에 미치는 효과를 검토하기 위하여 캡슐트레인 모델을 기반으로 한 동특성 해석 시뮬레이션을 수행하였다. 검토 결과, 현가장치 내 감쇠 제어를 통해 ISO 기준의 승차감 규격을 만족할 수 있음을 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.656-660
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• 2009

Various dynamic models of seated posture human body have been developed because the importance about the ride comfort assessment of vehicles is highly emphasized from day to day. The dynamic models of human body make possible the simulation of ride comfort assessment by applied to the vehicle dynamic model. Recently, the importance of ride comfort is also regarded to working vehicles such as excavators and the research of the ride comfort assessment for working vehicle is required. Only vertical vibration dominantly occurs on the seat of the private car driving with constant velocity. In contrast, vertical/fore-and-aft/pitch vibration seriously occurs on the seat of the working excavator. So, the dynamic models of seated human body applied to working vehicles should describe the dynamic characteristics for vertical/fore-and-aft/pitch direction. In this paper, the dynamic characteristics of seated human body are represented as apparent inertia matrix. The apparent inertia matrix is obtained by the vertical/fore-and-aft/pitch excitation of seated human body. 6 resonance frequencies are observed in apparent inertia matrix. This result can be applied to develop the dynamic model for seated posture human body.

• 한국소음진동공학회논문집
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• 제21권12호
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• pp.1159-1165
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• 2011

This paper presents ride comfort characteristics of a quarter-vehicle magneto-rheological(MR) suspension system with respect to different tire pressure. As a first step, controllable MR damper is designed and modeled based on both the optimized damping force levels and mechanical dimensions required for a commercial full-size passenger vehicle. Then, a quarter-vehicle suspension system consisting of sprung mass, spring, tire and the MR damper is constructed. After deriving the equations of the motion for the proposed quarter-vehicle MR suspension system, vertical tire stiffness with respect to different tire pressure is experimentally identified. The skyhook controller is then implemented for the realization of the quarter-vehicle MR suspension system. Finally, the ride comfort analysis with respect to different tire pressure is undertaken in time domain. In addition, a comparative result between controlled and uncontrolled is provided by presenting vertical RMS displacement.