• 한국소음진동공학회논문집
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• 제12권8호
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• pp.626-631
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• 2002

A modified equation for the evaluation of discomfort of a seated human body exposed to differential vibration at the seat and the floor was proposed in this paper. Through the review and analysis of the preceding studies, effect of phase difference between the seat and the floor vibration on discomfort were quantitatively identified. The phase effect was shown to be governed by not only phase difference between the two vibrations but both their frequency and the magnitude, which means the present equation for the evaluation of perceptual amount of vibration provided by ISO 2631-1 should be modified. The proposed equation was developed such that the correction function was multiplied to the present equation. The correction function consisted of three parts, each of them represented the effect by phase difference, frequency and vibration magnitude on discomfort respectively.

• 소음진동
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• 제10권5호
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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.

• 한국자동차공학회논문집
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• 제8권3호
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• pp.171-180
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• 2000

This paper deals with the whole-body vibration and ride quality evaluation in the vertical direction. The responses of the floor, hip, back, and head in four subjects were measured for various seats when the floor was excited by random vibration with r.m.s of 1.2m/s2 in the vertical direction. In the transmissibility between the hip and floor, the fundamental mode is observed at 4.4 Hz. In the transmissibility between the head and floor, the fundamental mode at 4.4Hz and the second mode at 7.6Hz are observed. It is shown that the head motion is 41% larger than the hip motion and the response of female subject is larger than that of male subject. The response without backrest also was compared with that with backrest. From these human responses ride quality of five seats were evaluated by the ride value such as transfer ration having frequency weighting function is the statistical sense. It is observed that the seat having high damping property can reduce the most acceleration exposed to hip in the statistical sense for all ride valves, while the seat having different seat spring doesn't show statistical difference.

• 동력기계공학회지
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• 제3권3호
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• pp.91-96
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• 1999

This study is about the design and analysis ot a suspension damper for truck driver's seat to improve the ride comfort. Trucks are usually subjected to hostile driving environments. Therefore, many truck driver's seat have suspension seats to isolate the vibration from the cab floor panel. Because the vehicle suspension system can reduce the primary vibration from the ground, only low frequency vibration can be transmitted to the driver's seat. But, this low frequency vibration can be harmful to the driver. The seat damper is very critical element to improve the ride comfort for the driver. In this study, a four-stage damper is designed and analyzed for the vibration capability. The damping coefficient of this damper can lie manually controlled in response to the road and driving environment.

• 한국산업보건학회지
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• 제7권1호
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• pp.87-98
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• 1997

In this study, subway train vibration has been measured to characterize the whole body vibration of Seoul subway lines for various human postures. Results show that the floor vibration level of the subway trains in the vertical direction is higher than that in other directions. At the standing human posture, vibration level of the head in the right-left direction are increased while that in the vertical direction is decreased. It is assumed that the different flexibility of the human body and the rolling motion of the subway trains are the main cause. At the sitting posture with back seat on, vibration level in the right and left direction at the human ischial tuberosities is lower than that in other directions. Results also show that there were little difference between back-seat on model and back-seat off model. Transmissibility analysis shows how the subway vibration affects the response of a human body.

• 한국철도학회논문집
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• 제18권3호
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• pp.194-202
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• 2015

본 연구에서는 수직 진동에 노출된 승객의 승차감을 정량적으로 분석하기 위해 점탄성 특성을 가진 시트에 기댄 인체의 동적 모델링을 제시한다. 시트 위 인체의 운동을 기술하기 위해 문헌에서 찾은 5자유도계 다물체 동역학 모델이 이용되었다. 철도차량 시트에 사용되는 점탄성 특성은 비선형 강성 특성과 시간 지연을 표현하는 컨볼루션 적분으로 수식화된다. 바닥 가진에 대한 전달함수를 분석 결과 시트의 비선형 특성으로 인해 입력 가진의 크기에 따라 전달함수는 변하는 것으로 나타났다. 측정된 철도차량의 바닥 가진을 이용하여 실제적인 인체 진동 특성을 분석한다. 주파수 가중치 자승평균치 값을 계산하고 시트 설계 파라미터가 이 주파수 가중치 자승평균치에 미치는 영향을 제시한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.409-414
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• 2011

The drivers of commercial vehicle easily feel tired because of a long time driving and bad road condition. Therefore it is very important to make the driver seat comfortable. This paper introduces the suspension system of driver's seat using magnetic force. The combination of linear spring and magnetic force can make nonlinear spring which has optimal stiffness for minimal vibration transmissibility. The vibrations of driver's seat floor are measured in various road condition. And the numerical simulations and experiments are performed to define the optimal parameter of magnetic suspension system.

• 한국산학기술학회논문지
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• 제13권12호
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• pp.5689-5695
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• 2012

본 연구에서는 차량에 적용되는 시트 재질인 폴리우레탄 폼의 점탄성 특성을 고려하여 시트와 인체의 진동특성을 시험 및 수치해석 방법을 이용하여 분석하였다. 압축 시험을 통해 폴리우레탄 폼의 점탄성 특성인 비선형성과 준-정역학적 특성을 구하였다. 또한 컨벌루션 적분법 및 비선형 강성 모델을 이용하여 폴리우레탄 폼의 점탄성 특성을 수학적으로 모델링하였다. 시트의 승차감 기여도를 분석하기 위하여 시트의 동역학 모델과 ISO5982의 표준 인체 수직진동 모델을 이용하여 수직 진동모델을 구성하고 관련 운동방정식을 유도하였다. 비선형 운동방정식은 Runge-Kutta 적분법을 이용하여 수치해석 시뮬레이션을 수행하였다. 철도차량의 차체 바닥에서 측정한 진동가속도 입력에 대한 시트와 인체의 응답 특성을 분석하고 시트 설계 파라미터에 대한 승차감 지수 값들의 변화를 분석하여 시트 설계에 대한 방법론을 제시하고자 한다.

• 한국소음진동공학회논문집
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• 제20권6호
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• pp.577-582
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• 2010

The squeak propensity in the gear box of an automotive seat system is investigated analytically. The mating parts in the gear box are the lead screw and the nut, where the friction stresses are exerted on the thread of the screw. The lead screw is modeled as a circular beam allowing the bending and torsional vibrations. In the system, the lead screw converts rotating to translating motion so that it moves the automotive seat slightly tilted on the floor. The tilting angle is considered one major parameter in this study. Therefore, the equations of motion associated with the non-conservative friction force are derived with the inclusion of the tilting angle. It is found that the squeak noise corresponds to the several bending modes of the lead screw and its propensity is increased by the tilting angle of the seat.

• 대한인간공학회지
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• 제32권4호
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• pp.381-387
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• 2013

Objective: This paper studies the method of measuring whole-body vibration in the car and terms associated. Background: Human exposure to vibration can be broadly classified as localized and whole-body vibration. The whole-body vibration affects the entire body of the exposed person. It is mainly transmitted through the seat surfaces, backrests, and through the floor to an individual sitting in the vehicle. It can affect the comfort, performance, and health of individuals. Method: Human responses to whole-body vibration can be evaluated by two main standards such as ISO 2631 and BS 6841. The vibration is measured at 8 axes - three translations at feet, 3 translations of hip and two translations of back proposed by Griffin. B&K's sensors used in this study are the 3-axes translational acceleration sensor to measure the translational accelerations at the hip, back and foot. Results: The parameters associated with the whole-body vibration in the car are frequency weightings, frequency weighted root-mean-square, vibration dose values, maximum transient vibration value, seat effective amplitude transmissibility, ride values and ride comfort. Conclusion: Studied the evaluating methods of vibration exposure and ride comfort. Application: Evaluation of whole-body vibration in the car.