• Journal of Astronomy and Space Sciences
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• 제31권4호
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• pp.347-351
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• 2014

Planetary exploration rovers are likely to make a trip on a winding and sloping road of irregular surfaces to the destination in order to accomplish scientific missions. One of the key technologies for rovers is a suspension for traveling and performing exploration missions; the suspension is an essential area of technology for a stable movement of a rover. In this study, an 8-wheel suspension is designed to enable efficient climbing of slopes on a passage to the destination. For the two front wheels among the eight wheels, the moment at the pivot connecting two wheels is derived when the distance between the wheels and the torque of wheels are same. A test experiment was performed to compare the magnitude of moment according to the change in tilt angle and the position of the pivot. Finally, a suspension design considering the position of the pivot was proposed to enhance the hill-climbing performance.

• 한국자동차공학회논문집
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• 제8권6호
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• pp.156-164
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• 2000

In this study, a discrete time model for a simplified front wheel suspension system which has nonlinear dampling and stiffness property is introduced. The model is estimated from the discrete data which are generated based on the real car parameter. The performance of the proposed method is evaluated through numerical simulation, and the simulation results show that the proposed method can estimate the nonlinear behavior of the suspension system very well.

• 한국자동차공학회논문집
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• 제7권8호
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• pp.262-271
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• 1999

To design suspension system and estimate its durability , the loading history of each suspension part exposed to various operation conditions should be known from either measurement or computations. Based on these results, stress analysis is carried out to obtain the optimal shape and to reduce the production cost through the proper selection of manufacturing process. In this paper, first the measurement of 3-directional accelerations of wheel center using an accelerometer are undertaken from a vehicle running on Belgian road. Then the data measured from experiments are pre-processed with filtering . Based on the pre-processed data the methodology for determining the dynamic loading to each suspension part is developed by simply modeling the suspension system with ADAMS software. Eventually , it is expected that dynamic loadings can be used for the dynamic stress and fatigue analyses.

• 한국양식학회지
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• 제14권1호
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• pp.43-50
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• 2001

To study the effect of paddle wheel on water circulation, velocity components were measured in shrimp ponds both along the longitudinal direction from a single paddle wheel and at 25 grid points of two ponds, which have mean water depth of 1.2m and aspect ratio (length/width) 1.05 and 0.68, respectively. An analysis of factors related to water quality and circulation showed that I) a single paddle wheel has an effective distance of 33m for de-stratification, 16m for particulate suspension and 25m for removal of organic material, dispersion of DO and prevention of bed sediment disturbance and ii) with doubling the number of paddle wheels at the pond corners, the flow speed increased by 13% over the ponds, while it reduced by 8.5% around the pond centres. Contrary to expectation, increasing the number of paddle wheel did not generate strong circulation around the pond centre and improve water quality.

• 대한기계학회논문집A
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• 제33권8호
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• pp.832-841
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• 2009

Wheels of UGV can be used to get the information about the ground. However, wheels of UGV with actively articulated suspension cannot be used as the roles because the each wheel does not remain in contact with the ground. Therefore, in this study, we proposed the indexes and models to estimate the contact wheels. First, we formulated the dynamic equations about the actively articulated suspensions and wheels. Then estimation index $I_{WTC}$ and $I_{ATC}$ were developed from the equations, and analyzed the strengths and weaknesses of each index. As the results, we developed the fuzzy rule-based estimation model additionally derived from our observations. $I_{WTC}$ model and $I_{ATC}$ model could eliminate the noise of about 60% in comparison with the result without the estimation model. Fuzzy model also could reduce the noise of about 83%. In addition, fuzzy rule-based estimation model had high sensitivity and precision as well as robustness.

• 한국자동차공학회논문집
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• 제7권8호
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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.

• 한국소음진동공학회논문집
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• 제11권8호
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• pp.349-356
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• 2001

The dynamic behavior of high speed train is very Important because the railway should be safe and Is satisfied tilth the rode comfort of passengers. The train is composed of many suspension components. such as 1st springs, 1st dampers, 2nd springs and 2nd dampers, that have an influence on the dynamic characteristics of high speed train. Also, the wheel/rail shapes, the track conditions and geometry and many environmental factors, such as rain, snow and wind. affect the dynamic behavior of high speed train. This paper reviews the effect of wind and track conditions on the dynamic behavior of high speed train. The VAMPIRE program Is used for this simulation. The result of simulation shows that the high speed train should not be operated when the wind velocity is beyond 34.5 m/sec.

• 소음진동
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• 제8권4호
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• pp.683-689
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• 1998

A control algorithm for multi-stage dampers is developed based on the mode skyhook control concept, and implemented on the full vehicle system environment. The test vehicle system is equipped with the real time controller, four-stage variable dampers and sensors. The real time controller is developed using a digital signal processor(DSP), digital I/O, A/D and D/A converters. The dampers are driven by the electromagnetic actuators of less than 20 msec response time. The sensors include accelerometers, relative displacement transducers, and steering wheel rate sensors, etc. Through a series of tests in laboratory and proving ground, the performance of the semi-active suspension system is evaluated and it is shown that the vehicle dynamic characteristics is improved with the developed damping system. Futhermore, the parameter tuning methods to enhance vehicle dynamic performance are propsoed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 추계학술대회 논문집
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• pp.542-549
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• 1999

The purpose of this study is to investigate stability of a high speed train and to propose optimal design using sensitivity analysis of suspension design parameters. A form of equations of motion in tangent track and curve track is obtained based on each creep force. Tangent track and curve track equations include lateral, rolling and yawing motions of wheel sets, bogies, and carbodies. Three track cases have been chosen to stability assesment of a high speed train analysis. Sensitivity equations are set up by directly differentiating the equations of motion. This study def'.led Stability performance index of a high speed train in tangent track and curve track. The relative magnitude of the effect of suspension parameters on the critical speed is computed, and by adjusting these parameters, the increase of the critical speed is achieved.

• 한국소음진동공학회논문집
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• 제24권8호
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• pp.592-599
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• 2014

A torsional vibration at driveline happens seriously at rapid vehicle acceleration. The torsional vibration at driveline can be reduced by optimization of joint angle and yoke phase angle of driveline. But, the joint angle of driveline is changed according to vehicle driving condition as acceleration, deceleration, forward and backward driving, so that excessive vibration is transmitted to vehicle body at specific driving condition. Especially under rapid acceleration condition, vibration transmitted to body could be maximized because excitation force at rapid acceleration is bigger than that at normal driving condition due to changed joint angle. The torsional vibration of driveline can be kept at low level by controlling suspension parameter to minimize rigid axle displacement as well as optimizing joint angles considering the vehicle acceleration condition.