• Title/Summary/Keyword: Vehicle motion

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Prediction of the Dynamic Derivatives of Separated Payload Fairing Halves by the CFD Analysis of Forced Harmonic Motions (강제조화운동 전산유동해석을 통한 분리된 페어링 동안정 미계수 예측)

  • Kim, Yeong-Hun;Ok, Ho-Nam;Kim, In-Seon
    • Aerospace Engineering and Technology
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    • v.5 no.2
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    • pp.149-158
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    • 2006
  • A review has been made on what kind of method can be applied to predict the dynamic derivatives of the separated PLF(Payload Fairing) halves of a launch vehicle in consideration of technology and budget. An optimal approach is selected considering the geometric characteristics of the PLF halves, the aerodynamic conditions and the required accuracy. The time history of aerodynamic force/moment coefficients are obtained for the forced harmonic motions by solving the unsteady Euler equations derived with respect to the inertial reference frame. and the dynamic derivatives are deduced by integration of the aerodynamic coefficients for one period. In this research, the dynamic derivatives are presented for 0.6$\leq$ M $\leq$2.0, $-180^{\circ}$ $\leq$$\alpha$ $\leq$$180^{\circ}$ and $-90 ^{\circ}$$\leq$$\beta$$\leq$$90 ^{\circ}$.

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Study on Vehicle Haptic-Seat for the Information Transfer to Driver (운전자 정보전달을 위한 차량용 햅틱시트 연구)

  • Oh, S.Y.;Kim, K.T.;Yu, C.H.;Han, K.S.;Kwon, T.K.
    • Journal of rehabilitation welfare engineering & assistive technology
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    • v.8 no.1
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    • pp.1-7
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    • 2014
  • In this study, the effect of the automotive haptic-seat technology which can transmit the driving information by the vibro-stimulus from the seat was investigated to overcome previous system's limitation relied on the visual and audial method and to help handicap driving. A prototype haptic seat covers with 30 coin-type motors and driver module were developed for this sake. A driving simulator on the 6-DOF motion-base was used for driving situation and we executed the seat vibro-stimulus test with 10 young participants who have normal tactile sense. The haptic recognition ratio by 30 locations was measured and analyzed in the result. The intensity of vibro-stimulus was adjusted by input voltage of motors (1.5V,2.5V,3.5V). All vibro-stimulus locations at 2.5V and 3.5V could be recognized by all participants and even in the lowest recognition ratio of 1.5V. The results showed that the seat vibration stimulus could be useful to transfer the drivers' information while driving.

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Underwater Hybrid Navigation System Based on an Inertial Sensor and a Doppler Velocity Log Using Indirect Feedback Kalman Filter (간접 되먹임 필터를 이용한 관성센서 및 초음파 속도센서 기반의 수중 복합항법 시스템)

  • Lee, Chong-Moo;Lee, Pan-Mook;Seong, Woo-Jae
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2003.05a
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    • pp.149-156
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    • 2003
  • This paper presents an underwater hybrid navigation system for a semi-autonomous underwater vehicle (SAUV). The navigation system consists of an inertial measurement unit (IMU), an ultra-short baseline (USBL) acoustic navigation sensor and a doppler velocity log (DVL) accompanying a magnetic compass. The errors of inertial measurement units increase with time due to the bias errors of gyros and accelerometers. A navigational system model is derived to include the error model of the USBL acoustic navigation sensor and the scale effect and bias errors of the DVL, of which the state equation composed of the navigation states and sensor parameters is 25 in the order. The conventional extended Kalman filter was used to propagate the error covariance, update the measurement errors and correct the state equation when the measurements are available. Simulation was performed with the 6-d.o.f. equations of motion of SAUV in a lawn-mowing survey mode. The hybrid underwater navigation system shows good tracking performance by updating the error covariance and correcting the system's states with the measurement errors from a DVL, a magnetic compass and a depth senor. The error of the estimated position still slowly drifts in horizontal plane about 3.5m for 500 seconds, which could be eliminated with the help of additional USBL information.

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A Hybrid Navigation System for Underwater Unmanned Vehicles, Using a Range Sonar (초음파 거리계를 이용한 무인잠수정의 수중 복합 항법시스템)

  • LEE PAN-MOOK;JEON BONG-HWAN;KIM SEA-MOON;LEE CHONG-MOO;LIM YONG-KON;YANG SEUNG-IL
    • Journal of Ocean Engineering and Technology
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    • v.18 no.4 s.59
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    • pp.33-39
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    • 2004
  • This paper presents a hybrid underwater navigation system for unmanned underwater vehicles, using an additional range sonar, where the navigation system is based on inertial and Doppler velocity sensors. Conventional underwater navigation systems are generally based on an inertial measurement unit (IMU) and a Doppler velocity log (DVL), accompanying a magnetic compass and a depth sensor. Although the conventional navigation systems update the bias errors of inertial sensors and the scale effects of DVL, the estimated position slowly drifts as time passes. This paper proposes a measurement model that uses the range sonar to improve the performance of the IMU-DVL navigation system, for extended operation of underwater vehicles. The proposed navigation model includes the bias errors of IMU, the scale effects of VL, and the bias error of the range sonar. An extended Kalman filter was adopted to propagate the error covariance, to update the measurement errors, and to correct the state equation, when the external measurements are available. To illustrate the effectiveness of the hybrid navigation system, simulations were conducted with the 6-d.o.f. equations of motion of an AUV in lawn-mowing survey mode.

Vision-based Target Tracking for UAV and Relative Depth Estimation using Optical Flow (무인 항공기의 영상기반 목표물 추적과 광류를 이용한 상대깊이 추정)

  • Jo, Seon-Yeong;Kim, Jong-Hun;Kim, Jung-Ho;Lee, Dae-Woo;Cho, Kyeum-Rae
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.3
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    • pp.267-274
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    • 2009
  • Recently, UAVs (Unmanned Aerial Vehicles) are expected much as the Unmanned Systems for various missions. These missions are often based on the Vision System. Especially, missions such as surveillance and pursuit have a process which is carried on through the transmitted vision data from the UAV. In case of small UAVs, monocular vision is often used to consider weights and expenses. Research of missions performance using the monocular vision is continued but, actually, ground and target model have difference in distance from the UAV. So, 3D distance measurement is still incorrect. In this study, Mean-Shift Algorithm, Optical Flow and Subspace Method are posed to estimate the relative depth. Mean-Shift Algorithm is used for target tracking and determining Region of Interest (ROI). Optical Flow includes image motion information using pixel intensity. After that, Subspace Method computes the translation and rotation of image and estimates the relative depth. Finally, we present the results of this study using images obtained from the UAV experiments.

A Study on Active Suspension Robust Control with Sensor and Actuator Location (센서위치를 고려한 능동 서스펜션 강인제어에 관한 연구)

  • Park Jung-Hyen;Jang Seung-Jae
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.10 no.6
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    • pp.1147-1152
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    • 2006
  • This paper proposed modelling and design method in suspension system design to analyze sky hook damper system by adopting active robust control theory. Recent in the field of suspension system design it is general to adopt active control scheme for stiffness and damping, and connection with other vehicle stability control equipment is also intricate, it is required for control system scheme to design more robust, higher response and precision control equipment. It is known that sky hook suspension system is better than passive spring-damper system in designing suspension equipment. We analyze location of sensor and actuator in sky hook system and its motion equation, then design robust control system. Numerical example is shown for validity of robust control system design in active sky hook suspension system.

A Delay and Sensitivity of Delay Analysis for Varying Start of Green Time at Signalized Intersections: Focused on through traffic (신호교차로의 출발녹색시간 변화에 따른 직진교통류의 지체 및 지체민감도 분식)

  • Ahn, Woo-Young
    • International Journal of Highway Engineering
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    • v.9 no.4
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    • pp.21-32
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    • 2007
  • The linear traffic model(Vertical queueing model) that is adopted widely in traffic flow estimation assumes that all vehicles have the identical motion before joining a queue at the stop-line. Thus, a queue is supposed to form vertically not horizontally. Due to the simplicity of this model, the departure time of the leading vehicle is assumed to coincide with the start of effective green time. Thus, the delay estimates given by the Vertical queueing model is not always realistic. This paper explores a microscopic traffic model(a Kinematic Car-following model at Signalised intersections: a KCS traffic model) based on the one dimensional Kinematic equations in physics. A comparative evaluation in delay and sensitivity of delay difference between the KCS traffic model and the previously known Vertical queueing model is presented. The results show that the delay estimate in the Vertical queueing model is always greater than or equal to the KCS traffic model; however, the sensitivity of delay in the KCS traffic model is greater than the Vertical queueing model.

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Latissimus Dorsi Transfer in Brachial Plexus Injury for the Elbow Flexion (상완 신경총 손상후 주관절 근력 회복을 위한 광배근 전이술)

  • Han, Chung-Soo;Chung, Duke-Whan;Soh, Jae-Ho
    • Archives of Reconstructive Microsurgery
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    • v.7 no.1
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    • pp.35-40
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    • 1998
  • The incidence of brachial plexus injury is increasing because of the development of motor vehicle but the the results of treatment was reported poor due to its complex anatomical structure and changes of function and sensory during the recovery after trauma. But the results of treatment has been improved by the recently introduced high sensitive diagnostic method that can evaluate accurately the site and extent of the injury and treatment method. Restoration of the elbow flexion is the most important goal of treatment after brachial plexus injury and nerve graft, neurotization and muscle transfer were used for methods of treatment. From December 1992 to May 1994, the author performed 6 cases of latissimus dorsi transfer at the same side for the improvement of elbow flexion in the patients of brachial plexus injury. There were 5 cases of male, one case of female and average age was 22 years old. The causes of injury were traffic accident in 3 cases, gun shot injury, falldown and birth injury in each one case and in all cases, the type of injury were upper arm type. The average follow up period were 1 year 5 months ranging from 12 months to 4 years 5 months. In all cases, active elbow flexion was impossible before operation and average muscle power was grade I. We analysed the active range of motion, muscle power and the functional results. At the last follow up, range of active elbow flexion was average $124^{\circ}$ and flexion contracture was average 11 degrees and the average of muscle power was grade IV. In the functional analysis, there were two cases of excellent, three cases of good and 1 case of fair. There was no complications including wound infection, vascular compromise and donor site problem. The results of latissimus dorsi transfer for improvement elbow flexion in the patients of brachial plexus injury is one of the useful mettled for the restoration of elbow flexion.

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Drag Torque Prediction for Automotive Wheel Bearing Seals Considering Viscoelastic as Well as Hyperelastic Material Properties (초탄성 및 점탄성 물성을 고려한 자동차용 휠 베어링 실의 드래그 토크 예측)

  • Lee, Seungpyo
    • Tribology and Lubricants
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    • v.35 no.5
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    • pp.267-273
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    • 2019
  • Wheel bearings are important automotive parts that bear the vehicle weight and translate rotation motion; in addition, their seals are components that prevent grease leakage and foreign material from entering from the outside of the bearings. Recently, as the need for electric vehicles and eco-friendly vehicles has been emerging, the reduction in fuel consumption and $CO_2$ emissions are becoming the most important issues for automobile manufacturers. In the case of wheel bearings, seals are a key part of drag torque. In this study, we investigate the prediction of the drag torque taking into consideration the hyperelastic and viscoelastic material properties of automotive wheel bearing seals. Numerical analysis based on the finite element method is conducted for the deformation analyses of the seals. To improve the reliability of the rubber seal analysis, three types of rubber material properties are considered, and analysis is conducted using the hyperelastic material properties. Viscoelastic material property tests are also conducted. Deformation analysis considering the hyperelastic and viscoelastic material properties is performed, and the effects of the viscoelastic material properties are compared with the results obtained by the consideration of the hyperelastic material properties. As a result of these analyses, the drag torque is 0.29 Nm when the hyperelastic characteristics are taken into account, and the drag torque is 0.27 Nm when both the hyperelastic and viscoelastic characteristics are taken into account. Therefore, it is determined that the analysis considering both hyperelastic and viscoelastic characteristics must be performed because of its reliability in predicting the drag torque of the rubber seals.

Damping and vibration analysis of viscoelastic curved microbeam reinforced with FG-CNTs resting on viscoelastic medium using strain gradient theory and DQM

  • Allahkarami, Farshid;Nikkhah-Bahrami, Mansour;Saryazdi, Maryam Ghassabzadeh
    • Steel and Composite Structures
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    • v.25 no.2
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    • pp.141-155
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    • 2017
  • This paper presents an investigation into the magneto-thermo-mechanical vibration and damping of a viscoelastic functionally graded-carbon nanotubes (FG-CNTs)-reinforced curved microbeam based on Timoshenko beam and strain gradient theories. The structure is surrounded by a viscoelastic medium which is simulated with spring, damper and shear elements. The effective temperature-dependent material properties of the CNTs-reinforced composite beam are obtained using the extended rule of mixture. The structure is assumed to be subjected to a longitudinal magnetic field. The governing equations of motion are derived using Hamilton's principle and solved by employing differential quadrature method (DQM). The effect of various parameter like volume percent and distribution type of CNTs, temperature change, magnetic field, boundary conditions, material length scale parameter, central angle, viscoelastic medium and structural damping on the vibration and damping behaviors of the nanocomposite curved microbeam is examined. The results show that with increasing volume percent of CNTs and considering magnetic field, material length scale parameter and viscoelastic medium, the frequency of the system increases and critically damped situation occurs at higher values of damper constant. In addition, the structure with FGX distribution type of CNTs has the highest stiffness. It is also observed that increasing temperature, structural damping and central angle of curved microbeam decreases the frequency of the system.