• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1080-1084
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• 2011

Urban maglev should have such characteristics as not only environmentally friendliness and excellent driving capability but also curve negotiation performance because its routes have many sharp curves. Due to normal mechanism of urban maglev its relative displacements of secondary spring are bigger than conventional railway vehicle and the centering force of levitation magnet is smaller than wheel-on-rail system. These features of maglev affect the curving negotiation and so the additional steering device is to be required on Urban maglev to improve the running performance at sharp curve of less than about R50m. Some developed urban maglev had the passive steering device which consists of mechanical linkage or hydraulic cylinder and closed-route piping. But it has drawback as complexity of layout of understructure of vehicle and functional limitation of passive mechanism regarding transient curve. These demerits could be solved by using active steering system. But it has a weak point that an active device should have actuators and additional inverter or hydraulic power source. In this paper, the semi-active steering system for urban maglev is to be introduced.

• Journal of Advanced Marine Engineering and Technology
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• 제31권3호
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• pp.215-223
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• 2007

When the propulsion shafting system of marine diesel engine is designed. the vibratory stresses on shafts should be reviewed and be satisfied with limits which are laid down by classification societies In addition. the torsional vibration aspects for crankshaft of main engine are requested to be checked by engine designers. Especially. for the 4, 5, and 6-cylinder engines. the 2nd order moment compensator(s) may be installed to compensate the external moments of engine and not to excite the hull girder vibration. This moment compensator which is mounted on fore and/or after-end of engine is driven by the roller chain drive for some of MAN 2-stroke diesel engines. While the engine is running, the roller chain Is worn down, which causes the extension of roller chain. The chain therefore should be checked and tightened by periods in order to keep its functionality. However. when the torsional angular acceleration of chain drive exceeds the certain limit. the chain will suffer the excessive slack and transverse vibration. This may cause fatigue, wear or damage on the chain and the chain ultimately may be broken. The research object of this thesis is to review factors which affect the angular acceleration of chain drive and to find out how to decrease the angular acceleration of driving chain by checking factors which have a major contribution to acceleration reduction using the statistical method of DOE(design of experiment), correlation analysis and regression analysis methods.

• 한국정밀공학회지
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• 제20권5호
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• pp.204-209
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• 2003

An elastomeric bushing is a device used in automotive suspension systems to reduce the load transmitted from the wheel to the frame of the vehicle. A bushing is an elastomeric hollow cylinder which is bonded to a solid steel shaft at its inner surface and a steel sleeve at its outer surface. The relation between the load applied to the shaft or sleeve and the relative deformation of elastomeric bushing is nonlinear and exhibits features of viscoelasticity. A load-displacement relation for elastomeric bushing is important for dynamic numerical simulations. A boundary value problem for the bushing response leads to the load-displacement relation which requires complex calculations. Therefore, by modifying the constitutive equation fur a nonlinear viscoelastic incompressible material developed by Lianis, the data fur the elastomeric bushing material was obtained and this data was used to derive the new load-displacement relation for radial response of the bushing. After the load relaxation function for the bushing is obtained from the step displacement control test, Pipkin-Rogers model was developed, Solutions were allowed fur comparison between the results of Modified Lianis model and those of the proposed model. It is shown that the proposed Pipkin-Rogers model is in very good agreement with Modified Lianis model.

• Journal of Biosystems Engineering
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• 제27권3호
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• pp.203-210
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• 2002

In this study, the leveling control system for a tractor has been developed. The experimental model showed that the implementation of the proposed hydraulic control system fur the prototype design of a slope land tractor was feasible. The front axle was designed as a center pin type and the rear axle was designed as a trailing arm type. The leveling control of the body on the slope land was accomplished by controlling the height of the right and left trailing arms using the electronic controlled hydraulic cylinder. The maximum leveling control angles were ${\pm}$15$^{\circ}$ for roll angle and 7$^{\circ}$far pitch angle. The front and rear wheel drives were transmitted by gears from the main shaft to the final drive. The adaptability of the hydraulic control system was tested and investigated by analyzing the system response in time and frequency domain. The hydraulic control system on a step input showed a linearly increasing trend without any overshoot state. The hydraulic control system on a frequency input showed a little phase differences and gain drops within the range of 0.3Hz.

• Elastomers and Composites
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• 제37권3호
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• pp.151-158
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• 2002

본 연구에서 고려된 elastomeric bushing은 자동차 현가장치에 사용되는 기계요소로서, 바깥쪽의 실린더형 슬리브와 안쪽의 실린더형 축 사이에서 가운데가 완전히 비어있는 실린더의 형태를 가진다. 본 연구에서는 일래스토메릭 부싱에 적용되는 힘과 변형의 관계가 비선형이고 점탄성의 특성을 보이므로, Lianis에 의해 발전되어진 비선형 점탄성 비압축 재료에 대한 구조방정식을 사용하여, 부싱의 축방향 응답에 대한 힘과 변위의 관계를 얻었다. 또한 변위에 의존하는 force relaxation function은 extrapolation method에 의한 ramp displacement control test로부터 완성되고, 이는 step displacement control test로부터 얻게된 결과와 비교하며, 두 결과가 매우 잘 일치됨을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.415-419
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• 2003

An elastomeric bushing is a device used in automotive suspension systems to reduce the load transmitted from the wheel to the frame of the vehicle. A bushing is an elastomeric hollow cylinder which is bonded to a solid steel shaft at its inner surface and a steel sleeve at its outer surface. The relation between the load applied to the shaft or sleeve and the relative deformation of elastomeric bushing is nonlinear and exhibits features of viscoelasticity. A load-displacement relation for elastomeric bushing is important for dynamic numerical simulations. A boundary value problem for the bushing response leads to the load-displacement relation which requires complex calculations. Therefore, by modifying the constitutive equation for a nonlinear viscoelastic incompressible material developed by Lianis, the data for the elastomeric bushing material was obtained and this data was used to derive the new load-displacement for radial response of the bushing. After the load relaxation function for the bushing is obtained from the step displacement control test, Pipkin-Rogers model was developed. Solutions were allowed for comparison between the results of Modified Lianis model and those of the proposed model. It is shown that the proposed Pipkin-Rogers model is in very good agreement with Modified Lianis model.

• 한국정밀공학회지
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• 제22권11호
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• pp.118-124
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• 2005

An automotive bushing is a device used in automotive suspension systems to reduce the load transmitted from the wheel to the frame of the vehicle. A bushing is a hollow cylinder, which is bonded to a solid steel shaft at its inner surface and a steel sleeve at its outer surface. The relation between the force applied to the shaft and the relative deformation of a bushing is nonlinear and exhibits features of viscoelasticity. In this paper, an automotive bushing is regarded as nonlinear viscoelastic incompressible material. Instron 8801 equipment was used for experimental res earch and ramp-to-constant displacement control test was used for data acquisition. Displacement dependent force relaxation function was obtained from the force extrapolation method and expressed as the explicit combination of time and displacement. Pipkin-Rogers model, which is the direct relation of force and displacement, was obtained and comparison studies between the experimental results and the Pipkin-Rogers results were carried out.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.703-708
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• 2002

An elastomeric bushing is a device used in automotive suspension systems to reduce the load transmitted from the wheel to the frame of the vehicle. A bushing is an elastomeric hollow cylinder which is bonded to a solid steel shaft at its inner surface and a steel sleeve at its outer surface. The relation between the load applied to the shaft or sleeve and the relative deformation of Elastomeric bushing is nonlinear and exhibits features of viscoelasticity. A load-displacement relation fur elastomeric bushing is important fur dynamic numerical simulations. A boundary value problem for the bushing response leads to the load-displacement relation which requires complex calculations and is hence unsuitable. Therefore, by modifying the constitutive equation for a nonlinear viscoelastic incompressible material developed by Lianis, the data fur the elastomeric bushing material was obtained and this data was used to derive the new load-displacement relation fur radial response of the bushing. After the load relaxation function for the bushing is obtained from the step displacement control test, Pipkin-Rogers model was developed. Solutions were allowed for comparison between the results of Modified Lianis model and those of the proposed model. It is shown that the proposed Pipkin-Rogers model is in very good agreement with Modified Lianis model.

• 한국자동차공학회논문집
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• 제7권5호
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• pp.154-161
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• 1999

An elastomeric bushing is a device used in automotive suspension systems to cushion the force transmitted from the wheel to the frame of the vehicle. A bushing is an elastomeric hollow cylinder which is bonded to a solid metal shaft at its inner surface and a metal sleeve at its outer suface. The relation between the force applied to the shaft or sleeve and their relative deformation is nolinear and exhibits features of viscoelasticity. Numerical solutions of the boundary value problem represent the exact bushing response for use in the method for determining the force relaxation function of the bushing. The new nonlinear viscoelastic bushing model, which is called Pipkin-Rogers model, is proposed and it is shown that the predictions of the proposed force-displacement relation are in very good agreement with the exact results. This new bushing model is thus very suitable for use in multi-body dynamics codes. The success of the present study for axial mode response suggests that the same approach be applied to other modes, such as torsional or radial modes.

• Elastomers and Composites
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• 제38권4호
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• pp.334-341
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• 2003

부싱은 차체로 전달되는 하중을 줄여주는 역할을 하는 자동차 현가장치의 부품으로 바깥쪽 슬리브와 안쪽의 축 사이에서 가운데가 비어있는 실린더의 형상을 가진다. 축에 작용되는 하중과 부싱의 상대 변위는 비선형 점탄성 성질을 나타내며, 부싱에서 힘과 변위의 관계는 다물체 동역학 시뮬레이션에 중요하다. 비선형 점탄성 축방향모드에 대하여 힘과 변위와의 직접관계식인 ??킨-라저스 모델을 리아니스 모델로부터 유도하였으며, 사인함수의 변위를 ??킨-라저스 모델에 적용하여 주파수와 변위의 변화가 비선형 점탄성 부싱 모델에 미치는 영향에 대하여 알아보았다.