• 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 2014년도 추계학술대회 논문집
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• pp.32-33
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• 2014

This paper presents control performances of a seat suspension system equipped with magnetorheological (MR) dampers using a new adaptive fuzzy sliding mode controller (FSMC). Adaptive fuzzy controller is formulated by considering the acceleration of the seat. It has been demonstrated that the proposed seat suspension system realized by the adaptive fuzzy sliding mode controller can provide effective performances such as reduced vibration.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.389-390
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• 2008

• 대한기계학회논문집A
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• 제28권11호
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• pp.1672-1684
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• 2004

In this paper, an active vibration control with the use of an air-cell seat for passenger cars is investigated. The roles of the air-cell inserted between the polyurethane foam of the seat and seat cover are first to extend the seat's capability to adopt various shapes of human body and to improve the ride-comfort against road disturbances. The air-cell seat is modeled as a 1-d.o.f. spring-damper system. Because an exact modeling of the air-cell itself is alomost impossible, its dynamic characteristics are analyzed through experiments. A road-adaptive gain-scheduled sky-hook control for the air-cell seat system is proposed. The skyhook gains are scheduled in such a way that the acceleration level transmitted to human body on various road conditions is minimized. Simulations and experimental results are provided.

• 한국자동차공학회논문집
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• 제19권5호
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• pp.67-75
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• 2011

A new energy absorbing mechanism for car seat was developed to reduce the neck injury in rear impacts. Energy absorbing principle is based on the shear-bolt behavior of thin-walled cast components subjected to static and dynamic loads. Results of shear bolt test using AM60 of Mg alloys showed robust behavior giving an approximately constant mean force during failure processes. Simply designed energy absorbing mechanism was assembled with the recliner between seat backs and seat rails. We have simulated the sled test of seat with dummy under the rear end impact using the finite element method. Results of simulation show that the new seat mechanism reduces thorax acceleration to a considerable extent, but it is not sufficient to mitigate neck injury indices e.g. neck shear force, neck tension force and NIC. With heightened headrest and narrowed backset, the energy absorbing mechanism resulted in good performance of protecting the neck injuries.

• International Journal of Automotive Technology
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• 제6권2호
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• pp.141-148
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• 2005

In order to reduce the time and costs of improving the performance of vehicle suspensions, the techniques for optimizing damping and air spring characteristic were proposed. A full vehicle model for a bus is constructed with a car body, front and rear suspension linkages, air springs, dampers, tires, and a steering system. An air spring and a damper are modeled with nonlinear characteristics using experimental data and a curve fitting technique. The objective function for ride quality is WRMS (Weighted RMS) of the power spectral density of the vertical acceleration at the driver's seat, middle seat and rear seat. The objective function for handling performance is the RMS (Root Mean Squares) of the roll angle, roll rate, yaw rate, and lateral acceleration at the center of gravity of a body during a lane change. The design variables are determined by damping coefficients, damping exponents and curve fitting parameters of air spring characteristic curves. The Taguchi method is used in order to investigate sensitivity of design variables. Since ride and handling performances are mutually conflicting characteristics, the validity of the developed optimum design procedure is demonstrated by comparing the trends of ride and handling performance indices with respect to the ratio of weighting factors. The global criterion method is proposed to obtain the solution of multi-objective optimization problem.

• 소음진동
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• 제11권1호
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• pp.76-81
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• 2001

This paper addresses experimental results carried out to investigate the transmission of seat vibration to the head for Korean. Vertical seat vibration in the frequency range of 0.5-30 Hz was applied to a seated Korean male subject. To examine the intra-variable effects on transmissibility, five different postures and three different vibration excitation levels were considered. The applied acceleration and head accelerations of the seated subject were measured simultaneously by using a 6-axes bite-bar. Detailed experimental results of measured transmissibilities are illustrated for each posture and/or vibration excitation level, and they were compared to an International Standard. They are found to allow the identification of dynamic characteristics of Korean seated body for various reat vibration environments. Furthermore, they are expected to be very useful in designing new seats for automotive and railway vehicles and in improving their vibration ride quality.

• 대한기계학회논문집A
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• 제32권7호
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• pp.549-555
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• 2008

Analytical method to analyze the tolerance effect on the vehicle ride comfort is suggested in this paper. Ride comfort is one of the most important performance indices which decide the vehicle design quality. In general, the ride comfort is affected by the variations of parameters of a vehicle model. Therefore, the effects of the parameters on the ride comfort need to be evaluated statistically based on the whole-body vibration of the vehicle. In this paper, weighted RMS values of the acceleration PSD of a seat position are used to define the ride comfort. The equations of motion and the sensitivity equations are derived based on a 5-DOF vehicle model. By employing the sensitivity information of the acceleration at the seat position, the tolerance effect on the vehicle ride comfort could be effectively analyzed.

• 한국자동차공학회논문집
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• 제6권1호
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• pp.16-26
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• 1998

The major effective factors on the ride quality of a vehicle are the vibration and noise of the engine and drive system. Engine contributes about 80% of the vibration and noise in the vehicle, and exciting forces of the engine are transmitted onto the vehicle frame through the engine mount. This paper studies the vibration reduction of a vehicle through the improvement of the engine mount. A computer program for optimal design is developed and the engine mount conditions are optimized to reduce the WRMS of PSD of acceleration at the driver's seat, which are caused by the exciting forces at the idle speed. Design variables are selected as the stiffness, mount angle and the location of the engine mount rubber. It is shown through computer simulation that the PSD of acceleration at the driver's seat can be improved by redesigning the engine mount system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.455-458
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• 2001

In this paper, ISO2631-1(1997) was used to assess the vibration and shock transmitted by train seat with respect to possible effects on human health. Evaluations have been performed on the seat acceleration measured in two type of train, Saemaulho and Mugunghwaho. For each train, limiting daily exposure durations were estimated by comparing the frequency weighted root mean square(i.e., r.m.s) acceleration and the vibration dose values(i.e., VDV), calculated according to ISO2631-1(1997) with exposure limits, health guidance caution zones.