• Journal of Biosystems Engineering
• /
• v.17 no.4
• /
• pp.314-325
• /
• 1992

This paper reviews some relevant criteria for the evaluation of ride quality of agricultural tractors. Although there still exist many deficiences and shortcomings, ISO 2631 'Guide for the evaluation of human exposure to whole body vibration' may be the most pertinent criterion to the ride quality evaluation of tractors. The effects of ride vibrations on the human health and performance were also reviewed and summarized in general terms.

• Journal of Sensor Science and Technology
• /
• v.14 no.3
• /
• pp.144-149
• /
• 2005

In this paper, we introduce the variation of ride characteristics for HSR 350x(Korea High Speed Train project) through on-line test during about 3 years. The concept of term "ride comfort" is equivocal. Generally it is evaluated as the vehicle vibration. The ride comfort for HSR 350x has been assessed by statistical method according to UIC 513R. The testing results show that HSR 350x has no problems from the viewpoint of the comfort ride on the high speed line and conventional line and that 1st and 2nd suspensions play an important role in the ride characteristics for high speed train.

• International Journal of Automotive Technology
• /
• v.7 no.3
• /
• pp.309-314
• /
• 2006

In this paper, the ride comfort from a computer simulation was compared to the experimental result. For measuring ride comfort of a passenger car, acceleration data was obtained from the floor and seat during highway running with different speeds. The measured acceleration components were multiplied by the proper weighting functions, and then summed together to calculate overall ride values. Testing several passenger cars, the ride comforts were compared. In order to investigate the effect of vibration signals on the steering wheel, an apparatus to measure the vibrations and weighting functions on the steering wheel were designed. The effect of the steering accelerations on the ride comfort were investigated and added for the overall ride comfort. For the computer simulations, Korean dummy models were developed based on the Hybrid III dummy models. For the Korean dummy scaling, the national anthropometric survey of Korean people was used. In order to compare and check the validity of the developed Korean dummy models, dynamic responses were compared to those of Hybrid III dummy models. The computer simulation using the MADYMO software was also compared to the experimental results.

• Journal of Biosystems Engineering
• /
• v.29 no.3
• /
• pp.207-216
• /
• 2004

This study was intended to investigate the characteristics of ride vibrations transmitted to tractor operator during rotary tillage and plowing operations. Seat accelerations of a 41 ps diesel tractor in rotary tillage and plowing were measured and evaluated as specified in the ISO 2631-1. Effects of working speed and tilling depth on ride vibration were investigated. The level of ride vibration was also evaluated in terms of health guidance caution zones. Some of the results of the study are as follows: 1. The level of ride vibration in plowing was about 4.3 times greater than in rotary tillage. 2. The effect of working speed in rotary tillage differs depending upon the tillage depth. The level of ride vibration was increased with the speed, but it decreased over a certain tillage depth. Fore and aft vibration was 2.2-2.7 times severer than horizontal and vertical vibrations. Dominant frequency band was 1-3.15 ㎐ in fore and aft, 1-3.15㎐ and 16-25㎐ in horizontal, and 16-25㎐ in vertical directions. 3. Plowing reduced the ride vibration by 42.8-50.2%. But its positive effect decreased as the plowing speed increased. In plowing operation, ride vibration was similar degrees in fore and aft, horizontal and vertical directions. The dominant frequency band in plowing operation was 1-2.5㎐ in fore and aft, 1-2.5㎐ in horizontal, and 1-8㎐ in vertical directions. 4. On a basis of daily work hours of 4, total level of ride vibrations in plowing operation is likely to be harmful to operator's health.

• Journal of the Ergonomics Society of Korea
• /
• v.32 no.4
• /
• pp.389-396
• /
• 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.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.69-74
• /
• 2011

In the curving detection method by using an accelerometer, the ride comfort in the first car is worse than one in the others due to spend the time to calculate the tilting command and drive the tilting mechanism after entering in the curve. In order to enhance the ride comfort in the first car, the preditive curve detection method which predicts the distance from a train to the starting point of curve by using the GPS, Tachometer, Ground balise and position DB for track. In this study, we predicted and evaluated the ride comfort for predictive curve detection method in transient curves according to the shape and dimension of transient curve and the various driving speed. Also, we predicted the improvement of the ride comfort for predictive curve detection method by comparing with the result of the ride comfort for predictive curve detection method and for curve detection method using an accelerometer in the short transient curve.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.4 no.6
• /
• pp.229-235
• /
• 1996

The tapered leaf spring is regarded as the adequate tool to improve ride quality and to reduce vehicle weight of commercial vehicles. These effects are due to minimizing the contact area of each leaf by reducing the number of leaves and by optimizing the thickness profile of each leaf. But in adapting the tapered leaf spring to improve ride quality, we often have some problems of bad pitching and bouncing motion. This paper shows the basic properties of tapered leaf spring by rig tests and how to improve ride quality of a vehicle with tapered leaf springs, compared with multi-leaf spring. From the results of vehicle tests and rig tests it is concluded that the ride quality was effected by the dynamic spring rate and the friction of the tapered leaf spring.

• Journal of Biosystems Engineering
• /
• v.26 no.3
• /
• pp.237-244
• /
• 2001

This work was intended to investigate the effect of vibration transmission paths on the ride vibration of tractor during the rotavating and transporting operations by applying the vibration path analysis method. Accelerations at the cab mounts were measured during the rotavating and transporting operations. Ride vibrations at the sear were than calculated using the measured accelerations at the cab mounts, and the frequency response functions and inertances between the seat and cab mounts, which were derived experimentally by the impact hammer test in static condition. The human sensitivity to vibration frequency was also taken into consideration for the calculation of ride vibrations at the 1/3 octave center frequencies in the frequency domain. Vibrations transmitted through rear cab mounts affected more significantly the ride vibration of tractor. The peak accelerations at the seat occurred at the frequencies of the engine and crank speed, and the frequency induced by tire lugs on the road transportation. It was found that the rear cab mounts should be improved in order to reduce the ride vibrations more effectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.1227-1231
• /
• 2001

To provide faster service and to relief the road traffic jam, the increase of service speed of conventional railway has been intensively considered. In this study, we measured and analyzed the vibration ride comfort of Saemaeul Train to evaluate the feasibility of 5km/h speed-up in curves and l0km/h speed-up on straight tracks. Four main lines, such as Honam, Kyungboo, ]anghang, Kyungjeon were chosen as representative lines for speed-up feasibility study. The increase of mean ride comfort index in case of speed-up is 0.5-2㏈. The mean ride comfort index of vertical direction in case of speed-up is 107 ∼110 ㏈ for Honam line, 104 ∼112 ㏈ for Kyungboo line, 108∼112 ㏈ for Janghang line and 105∼108 ㏈ for Kyungjeon line. Through this study, we found that the Saemaul Express has slight margin to increase the service speed from the view point of vibration ride comfort.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.686-691
• /
• 2007

The ride comfort is more important according to train speedup. Generally it is defined as the vehicle vibration. There are many studies on evaluation method of ride comfort for railway. In the case of Korean high speed train(HSR 350x), the ride comfort has been assessed by statistical method according to UIC 513R. To verify the design requirements for the performance of HSR 350x, the qualification tests had been conducted from August 19, 2002 to December 2004 and the stabilization and reliability tests are carried out nowadays. Up to December 2006, total test runs and the accumulated milage of the train were 357 times and 164,000km, respectively. A total of 352 ride indices had been acquired through the on-line test from Aug. 2002 to Dec. 2006. In this paper, we have reviewed the characteristics of ride comfort for HSR 350x according to the operational conditions, such as load and track conditions, season and used time, by using the tests data.