• Journal of KSNVE
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• v.7 no.6
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• pp.1025-1030
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• 1997

This paper introduces the experimental results of ride values assessed for several passenger cars. The experiment was conducted at four vehicles on two roads for three persons by measuring the acceleration in the 12-axis of human. The results include the comparison of the ride values, such as the component ride values, overall ride value, and seat effective amplitude transmissibiity. It is proved that acceleration between 1 and 15Hz is the most significant in evaluating the ride quality. The contribution of the acceleration in each measurement axis is quantified from the component ride value. SEAT value shows a relatively low sensitivity for the road condition and human mass.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2001.02a
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• pp.16-21
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• 2001

The ride quality of agricultural tractor seats is evaluated based on the vibration of the human bodies. Tractor ride vibration levels have been measured at the person-seat interface along 7 axes(3 translational axes at the feet, 3 translational axes on a seat surface and 1 axis at the seat back), under different operating conditions. Since one of the most important parameters for ride comfort is the level and duration of the root mean square acceleration experienced, the ride values, such as the seat effective amplitude transmissibility, the component ride value, and the overall ride value based on acceleration root mean square are evaluated for a conventional tractor using frequency weighting functions and axis multiplying factors. The ride indices are also studied considering to the variation of vehicle speed and road profile.

• Journal of KSNVE
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• v.10 no.5
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• pp.811-818
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• 2000

This paper deals with the design of a car seat for enhancing dynamic ride quality using a Biomechanical Model that was developed from the measured whole-body vibration characteristic. For evaluation of seat ride quality, the z-axis acceleration of floor as an input of biomechanical model was measured on a driving passenger car at highway and national road. Form the floor signal and the estimated biomechanical model, overall ride value evaluated by parameter study of seat stiffness and damping. The result shows that overall ride value decreases as the seat damping increases and the sear stiffness decreases. A lot of polyurethane foams were manufactured and tried to evaluate dynamic ride quality of a seat. It is found that stiffness and damping of a seat show a linear relationship, which means the stiffness and damping are not independent each other, So the optimal seat parameters within practically achievable space are determined.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.4
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• pp.1-9
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• 2009

A simplified model of seat-human body is presented to analyze vibrations of human body on a seat of vehicle. The theoretical model having seven degrees-of-freedom is composed of the inter-connected masses, springs and dampers. Until now, evaluation of ride comfort has been usually performed only through vehicle tests. This study aims to complement shortcomings of conventional vehicle tests in evaluation of ride comfort by using the theoretical model. The acceleration values of the human body are obtained from frequency response functions of the theoretical model. Thereafter, Ride and SEAT indexes are acquired by considering response characteristics of the human body for the 12 axes that are presented in BS 6841. A vehicle test is carried out to measure the acceleration values for the three parts of the human body such as upper body, hip and foot. Ride and SEAT indexes of the vehicle test are also obtained by considering the response characteristics of the human body, of which results are compared with the values from the theoretical model. It is found that the theoretical results are in good agreement with the experimental results.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.205-212
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• 2003

This paper may provide a basic design data for the safer car seat mechanism and the quality of the material used by finding out the passenger's dynamic behavior when protected by seat belt during collision. A computer simulation with finite element method is used to accomplish this objective. At first, a detailed geometric model of the seat is constructed using CAD program. The formation of a finite element from a geometric data of the seat is carried out using Hyper-Mesh that is the commercial software for mesh generation and post processing. In addition to seat modeling, the finite element model of seat belt and dummy is formed using the same software. Rear impact analysis is accomplished using Pam-Crash with crash pulse. The part of the recliner and right frame is under big stress in rear crash analysis because the acceleration force is exerted on the back of the seat by dummy. The stress condition of the part of the bracket is checked as well because it is considered as an important variable on the seat design. Front impact model which including dummy and seal belt is analyzed. A Part of anchor buckle of seat frame has high stress distribution because of retraction force due to forward motion of dummy at the moment of collision. On the basis of the analysis result, remodeling and reanalysis works had been repeatedly done until a satisfactory result is obtained.

• Journal of the Ergonomics Society of Korea
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• v.15 no.1
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• pp.69-78
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• 1996

Current fighter pilots, flying new generation aircrafts with high performance, are under severe stress during aerial combat maneuvering when they are exposed to high sustained +Gz(Head-to-foot) acceleration stress. Two major factor limiting performance during high sustaied +Gz acceleration stress are loss of vision-greyout or blackout, and loss of consciousness (LOC). These symptoms are believed to occur as a result of insuff- icient blood flow to the retina and the brain. This study was conducted to evaluate the effects of high sustained +Gz stress under different seat back angle. The results. obtained by the biodvanmic computer simulations using the ATB(articulated total body) model, are represented with respect to three variables, such as HIC(head injury criterion) value, average G, and maximum G. The results demonstrate that the seat back angle(over $30^{\circ}C$) had a significant effect to decrease +Gz stress on the head segment and had no significant effect on HIC.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.584-589
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• 2001

This paper presents the dynamic parameter design optimization of a suspension seat system using the genetic algorithm. At first, an equivalent 1-D.O.F. mass-spring-damper model of a suspension seat system was constructed for the purpose of its vibration analysis. Vertical vibration response and transmissibility of the equivalent model due to base excitations, which are defined in the ISO's seat vibration test codes, were computed. Furthermore, seat vibration test, that is ISO's damping test, was carried out in order to investigate the validity of the equivalent suspension seat model. Both analytical and experimental results showed good agreement each other. For the design optimization, the acceleration transmissibility of the suspension seat model was adopted as an object function. A simple genetic algorithm was used to search the optimum values of the design variables, suspension stiffness and damping coefficient. Finally, vibration ride performance test results showed that the optimum suspension parameters gives the lowest vibration transmissibility. Accordingly the genetic algorithm and the equivalent suspension seat modelling can be successfully adopted in the vibration ride quality optimization of a suspension seat system.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.12
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• pp.1199-1205
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• 2011

In the present work, a seat suspension system adopting semi-active damper is evaluated for driver's ride quality. A cylindrical type of ER(electrorheological) damper is designed and manufactured for the seat suspension of heavy vehicles. The governing equation is derived under consideration of human vibration. A sliding mode controller is then synthesized and experimentally realized on the manufactured ER seat suspension while a driver is sitting on the controlled seat. Ride quality is evaluated by fatigue decreased proficiency boundary, vibration dose value and crest factor utilizing weighted-acceleration according to ISO2631.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.7
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• pp.572-577
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• 2005

This paper applies the fuzzy logic controller to a semiactive seat suspension system in order to obtain the better ride comfort in constraint of specific rattle space. The seat suspension system used for this research is a scissors-type one with the MR (Magneto Rheological) fluid damper. Since a seat suspension system with a driver can not be exactly modeled, it is effective to control with the fuzzy logic controller. The rule was carefully tuned to effectively reduce the vibration transmitted to a driver. The on-road ride was realized on a hydraulic excitor and the result shows that the fuzzy controller has reduced the vibration of a seat suspension system compared to the continuous skyhook controller.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.160-171
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• 1999

The paper examines the ride performance enhancement that can be obtained by applying hydraulic semiactive vibration absorbers(SAVa) to alter the compliance characteristics of the seat/wheel suspension system. The work relies on a consistent model of the (nonlinear) hydrodynamics of the SAVA. A recently developed Lyapunov control scheme is used to provide regulation.. The performance is first examined assuming a quarter car with a seat/seat mounted mass. The paper then employs a quarter car/seat with a two mass ISO model of the seated human . The simulated results indicated that a reduction of 45% of the peak vertical acceleration is achievable with new system.