• 한국소음진동공학회논문집
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• 제26권1호
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• pp.82-88
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• 2016

This paper proposes a new type of semi-active direct-drive valve(DDV) car suspension system using piezoelectric actuator associated with displacement amplifier. As a first step, controllable piezoelectric DDV damper is designed and governing equation of a quarter-vehicle suspension system consisting of sprung mass, spring, tire and the piezostack DDV damper is constructed. After deriving the equations of the motion, in order to control spool displacement and damping force the skyhook controller is designed and applied. The performance evaluation of the proposed semi-active suspension system is conducted with different displacement of spool. Then, the ride comfort analysis is undertaken in time domain with bump road profile.

• 제어로봇시스템학회논문지
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• 제8권3호
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• pp.199-207
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• 2002

In this paper, a self-tuning gain-scheduled skyhook control for semi-active suspension systems is investigated. The dynamic characteristics of a continuously variable damper including electro-hydraulic pressure control valves is analyzed. A 2-d.o.f. time-varying quarter-car model that permits variations in sprung mass and suspension spring coefficient is considered. The self-tuning skyhook control algorithm proposed in this paper requires only the measurement of body acceleration. The absolute velocity of the sprung mass and the relative velocity of the suspension deflection are estimated by using integral filters. The skyhook gains are gain-scheduled in such a way that the body acceleration and the dynamic tire force are optimized. An ECU prototype is discussed. Experimental results using a 1/4-ear simulator are discussed. Also, a suspension ECU prototype targeting real implementation is provided.

• 한국자동차공학회논문집
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• 제18권2호
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• pp.74-82
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• 2010

Fretting damage can be observed in automobile and railway vehicle, fossil and nuclear power plant, aircraft etc. In the present study, railway axle material RSA1 used for evaluation of fretting fatigue life. Plain and fretting fatigue tests were carried out using rotary bending fatigue tester with proving ring and bridge type contact pad. Through these test, the following results are obtained: 1) it is found that the fretting fatigue limit of standard specimen decreased about 37% compared to the plain fatigue limit. 2) The early crack of Shinkansen type specimens initiated in contact area and final fractured below samp=214 MPa. 3) The early crack of all TGV type specimens initiated in rounded area and fractured. 4) Tire tracks and rubbed scars were observed in the oblique crack region and fatigue crack growth region of fracture surface. 5) The wear debris is observed on the contact surface, and oblique cracks at an earlier stage are initiated in contact area. These results can be used as useful data in a structural integrity evaluation of railway axle.

• Journal of Biosystems Engineering
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• 제26권1호
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• pp.1-10
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• 2001

Interactions between cage wheel and soil under the wet paddy field condition were analyzed. The cage wheel as a traction aid to driving tires of tractor was attached to the outside of the tires. The driving torque transmitted only to the cage wheel was measured and its effect on the total driving torque by both the tires and cage wheel was analyzed. Mathematical models were developed to predict the soil thrusts y a single lug and by the cage wheel with many lugs, respectively. Experimental results showed that as the diameter of cage wheel increased, positive effects of the cage wheel on the traction also increased. About 33-40% of the total traction force was obtained by the cage wheel with a diameter 1,182mm and 49-55% with a diameter 1,222mm. The peak thrust of the single lug of cage wheel increased by 31% and 59%, respectively when the diameter of the cage wheel increased from 1,182mm to 1,222mm and 1,262mm. The thrust by the cage wheel was estimated by using the developed mathematical models and the results were proved that the models are reliable for the estimation of the traction by the cage wheels.

• 한국자동차공학회논문집
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• 제9권3호
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• pp.100-107
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• 2001

The main goals of the automotive suspension systems are to isolate roadway unevenness from the tire and to improve vehicle stability. To overcome the performance limitation of the passive systems the active systems which completely replace the passive spring and damper elements with a force generating actuator has been studied. However, application of the system has been limited because it has required a significant amount of power. Recently, alternative systems which retain passive elements but include active elements have been developed to reduce the power required. Those systems are mostly focused on the control system which compresses the spring-damper directly. In this study, a new type of power efficient control system which makes the spring-damper unit slide in side way is studied. After constructing the control system including dynamic modeling and motion control, two types of alternative control systems are compared in view of power consumption and dynamic attitudes such as roll responses as well as heave responses. Also, a half car bond graph model is developed to show clearly the significant differences in performances between two control systems.

• 한국기계가공학회지
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• 제18권4호
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• pp.10-15
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• 2019

In this paper, we report a robust steering control using time delay control for the vehicle dynamics variation due to tire/road contact condition variation, the lateral disturbance force due to the side wind, and the yaw disturbance moment due to the difference between the left and right tires' pneumatic pressure. We controlled the side slip and yaw damping compensation for rapid steering at the high velocity of the vehicle. Based on the developed control, the driver can only consider the desired path without concerning on the vehicle dynamics variation, disturbances, and undesired side slip and yaw oscillations. Simulation results show that robustness from the vehicle dynamics variation and disturbances was achieved by using the developed time delay control. We evaluated the side slip and yaw damping compensation capability for the rapid steering at the high velocity of the vehicle in the cases of three control methods.

• 한국도로학회논문집
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• 제13권1호
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• pp.185-195
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• 2011

항공기 관련 사고는 많은 인명피해 및 물질적 손해가 크게 발생한다. 현재 국내 항공기 활주로 관련 사고는 전체 사고의 28%를 차지하고 있으며, 국제적으로 33%의 항공기 활주로 사고가 발생하였다. 이러한 사고를 예방하기 위하여 FAA에서는 규정에 미치지 못하는 활주로 종단안전구역에 과주방지 포장시스템의 설치를 의무화하고 있으며, 안전성 확보를 위하여 활주로 종단안전구역이 규정에 만족하더라도 과주방지 포장시스템의 설치를 권고하고 있다. 이러한 국제적 정세에 맞추어 국내에서도 과주방지 포장시스템에 대한 연구가 진행되고 있으며 과주방지 포장시스템의 국내 도입에 대한 절차도 이루어지고 있다. 이에 따라 본 연구에서는 과주방지 포장시스템에 대한 합리적인 성능평가를 하기위하여 FAA에서 사용하고 있는 ARRESTOR 프로그램과 3차원 비선형 동적해석이 가능한 LSDYNA를 이용하여 항공기의 활주로 과주에 따른 제동거리, 견인력, 수직력 및 관입량을 비교하였다. 해석 결과 제동거리는 비슷하게 해석되었고, 견인력 및 수직력은 다소 차이가 발생하였으나 경향은 비슷하게 도출되었다. 추후 다양한 항공기 조건 및 포장재료의 특징을 고려한 3차원 시뮬레이션 해석이 필요하며, 지속적인 시뮬레이션 해석 기법을 개발하여 보다 정확한 해석방법을 개발할 필요가 있다.

• 대한기계학회논문집A
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• 제37권7호
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• pp.905-912
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• 2013

고무는 독특한 점탄성적 성질로 인하여 여러 분야에서 광범위하게 사용되고 있다. 고무의 마찰은 지속적인 지면과의 접지로 인하여 발생되고, 결과적으로 마모가 발생한다. 이때 마찰에 의해 발생되는 마찰에너지는 마모 메커니즘의 중요 요인으로, 마찰에너지는 온도, 지면의 거칠기, 형상, 하중, 물성 등의 조건에 영향을 받는다. 본 연구에서는 마찰에너지에 대한 수직 하중과 수평 이동속도의 영향을 ABAQUS/explicit을 이용하여 해석하였고, 접지압, 전단력과 슬립 거리를 이용하여 마찰에너지를 계산하였다. 또한 실제 고무의 거동에 대한 실험 결과와 해석 결과를 비교하였다.

• 제어로봇시스템학회논문지
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• 제19권1호
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• pp.45-55
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• 2013

With the recent advancement of control method and battery technology, the electric vehicle have been researched to replace the conventional vehicle with electric vehicle with the view point of the environmental concerns and energy conservation. An electric vehicle which is equipped with the independent front steering system and in-wheel motors has advantage in terms of control. For example, the different torque which generated by left and right wheels directly can make yaw moment and the independent steering using outer wheel control is able to reduce the sideslip angle. Using of independent steering and driving system, the 4 wheel electric vehicle can improve a performance better than conventional vehicle. In this paper, we consider the method for improving the cornering performance of independent front steering system and in-wheel motor used electric vehicle with the compensated outer wheel angle and direct yaw moment control. Simulation results show that the method can improve the cornering performance of 4 wheel electric vehicle. We also apply the steering motor failure to steer the vehicle turned by the torque difference without steering. This paper describes an independent front steering and driving, consist of three parts; Vehicle Model, Control Algorithm for independent steering and driving and simulation. First, vehicle model is application of TruckSim software for independent front steering and 4 wheel driving. Second, control algorithm describes the reduced sideslip and direct yaw moment method in view of cornering performance. Last is simulation and verification.

• 대한토목학회논문집
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• 제33권4호
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• pp.1611-1617
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• 2013

동절기 도로구간에서 차량의 운행가능성 혹은 등판 가능성 정보는 교통 운영에 매우 중요한 요소이다. 특히, 빙설 구간을 운행할 경우 차량과 노면의 마찰력은 차량의 유형, 도로 기하구조의 특성 및 노면의 특성에 따라 다양하게 나타난다. 일반적으로 노면 결빙(적설)구간에서 트럭과 같은 후륜구동 차량은 전륜구동이나 4륜 구동 차량보다 마찰력이 낮으며, 갑작스런 강설시 이러한 차량의 무리한 도로 운행은 도로의 대규모 혼잡을 발생시키는 주요 원인으로 알려져 왔다. 따라서 도로의 기하구조 및 노면 특성과 차량의 유형에 기반한 실시간 도로 등판가능성 지표의 구축은 동절기 차량 및 도로의 운영 가능성 판단에 기반이 될 것으로 판단되다. 이러한 배경 하에 본 연구는 동절기 도로의 기하구조 및 노면 특성과 차량의 유형에 따른 도로의 운행가능성 지표를 구축방향을 제시하고자 하였다. 비록 제시된 지표는 국내 도로와 차량을 통해 구축된 결과는 아니지만, 향후 동절기 도로 및 차량 운영을 위한 지표 수립의 연구에 유용하게 활용될 것으로 기대된다.