• 대한의용생체공학회:의공학회지
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• 제19권6호
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• pp.603-609
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• 1998

가속도 변화에 따른 뇌의 미만성 부상을 해석하기 위하여 성인 및 2세, 6세아의 머리 부분에 대한 유한 요소 모델을 개발하였다. 외력은 최대값이 200g인 삼각형 형태의 가속도를 가하였으며, 가속도의 방향, 지속시간에 따른 변화를 해석하였다. 가속도 변화에 따라 발생되는 뇌내의 전단력 분포는 뇌간, 뇌교 및 중뇌등 신경조직이 밀집된 곳에서 크게 발생되어 이곳에서 미만형 부상이 발생할 확률이 높음을 알 수 있었으며, 특히 6세아 모델의 경우 뇌간에서의 최대 전단력이 굴전 형태의 회전가속도 받았을 때 가장 크게 나타나는 결과를 보여 개발된 모델이 임상결과와 일치함을 보여주고 있었다. 가속도 지속 시간이 길어짐에 따라 뇌내에 발생되는 압력 및 최대 전단력의 크기가 증대되고 있었으며, 유아모델의 경우 성인모델에 비하여 가속도 방향과 관계없이 낮은 압력이 발생하였지만 발생압력이 감소하지 않고 지속되는 현상을 보이고 있었다. 그리고 각 가속도에 의한 미만성 부상을 예방하기 위한 안전지수로는 현재 탑승자의 안전 설계에 활용되고 있는 HIC보다는 최대 전단응력이 더 적절한 부상 예측인자임을 알 수 있었다.

• 제어로봇시스템학회논문지
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• 제19권1호
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• pp.56-64
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• 2013

We propose an efficient minimum-time cornering motion planning algorithms for differential-driven wheeled mobile robots with motor control input constraint, under piecewise constant control input sections. First, we established mobile robot's kinematics and dynamics including motors, divided the cornering trajectory for collision-free into one translational section, followed by one rotational section with angular acceleration, and finally the other rotational section with angular deceleration. We constructed an efficient motion planning algorithm satisfying the bang-bang principle. Various simulations and experiments reveal the performance of the proposed algorithm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1190-1193
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• 2004

The purpose of this study is to evaluate the possibility of identifying joint damping property through commercially available isokinetic ergometer (BIODEX). The proposed method is to estimate the damping torque of the knee joint from the difference between the external joint torque for maintaining isokinetic movement and the gravity torque of the lower leg. The damping torque was estimated at various joint angular velocities, from which the damping property would be derived. Measurement setup was composed of the BIODEX system with an external force sensor and Labview system. Matlab was used in the analysis of the damping property. The experimental result showed that the small variation in angular velocity due to acceleration and deceleration of the crank arm resulted in greater change of inertial torque than the damping torque, so that the estimation of damping property from the isokinetic movement is difficult.

• Journal of Advanced Marine Engineering and Technology
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• 제30권6호
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• pp.760-769
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• 2006

This paper proposes an autopilot system using a fuzzy PID controller to satisfy performances required for the automatic navigation of ships under various marine circumstances. The existing autopilot system using a PD type controller has difficulties in eliminating a steady-state error and compensating nonlinear characteristics of ships. The autopilot system using the proposed fuzzy PID controller has a self-tuning ability, an ability to compensate nonlinear characteristics, and an ability to turn at constant angular velocity. Therefore. it can naturally make a steady-state error zero, compensate nonlinear dynamic effect of ships, have an adaptability to parameter variation owing to shallow water effect, and have an ability to turn ship's course rapidly without overshoot through procedures of acceleration, constant, and deceleration of angular velocity for large course-changing.

• 제어로봇시스템학회논문지
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• 제21권10호
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• pp.972-976
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• 2015

The objective of this research is to verify the quantitative efficiency of a bimanual robotic task. Bimanual robots can realize dexterous and complicated motions using two cooperating arms. However, its motion planning and control method are not simple for implementing flexible tasks such as assembly. In this paper, the proposed motion planning method is used to find an optimal solution satisfying a designed cost function and constraints with regard to the kinematics and redundancy of the bimanual robot. The simulation results show that the lifetime of the manipulator can be changed by the proposed cost function consisting of angular velocity and angular acceleration of each joint in the same assembly task.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.379-392
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• 1996

A mathematic model was developed for the simulation of sideways overturning of agricultural tractors on slopes. The overturning motion was described as a combination of the rotational motions with respect to the first and second tipping axes using the principle of conservation of angular mementum. A stability criterion was also established in terms of angular acceleration of tractor about the second tipping axis. Verification of the proposed model was provided by comparing the stability boundaries predicted by computer simulation with those observed experimentally for an equivalent 1/6 scaled mode tractor. A good agreement was shown between the simulation and experimental results.

• 한국자동차공학회논문집
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• 제17권3호
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• pp.102-109
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• 2009

The stumble (abrupt and big acceleration decrease) occurring in manual transmission vehicle while standing start is analyzed by simulation model. This model was verified by comparing to test results. Mechanism of the stumble is clarified by analyzing simulation results and the key mechanism of the stumble is angular vibration of powertrain including wheel and tires. As a result, several method that can reduce the stumble is proposed by carrying out parametric study, increasing low end torque of engine, increase gear ratio etc.

• Journal of information and communication convergence engineering
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• 제11권3호
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• pp.199-206
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• 2013

An emergency monitoring system for the elderly, which uses acceleration data measured with an accelerometer, angular velocity data measured with a gyroscope, and heart rate measured with an electrocardiogram, is proposed. The proposed fall detection algorithm uses multiple parameter combinations in which all parameters, calculated using tri-axial accelerations and bi-axial angular velocities, are above a certain threshold within a time period. Further, we propose an emergency detection algorithm that monitors the movements of the fallen elderly person, after a fall is detected. The results show that the proposed algorithms can distinguish various types of falls from activities of daily living with 100% sensitivity and 98.75% specificity. In addition, when falls are detected, the emergency detection rate is 100%. This suggests that the presented fall and emergency detection method provides an effective automatic fall detection and emergency alarm system. The proposed algorithms are simple enough to be implemented into an embedded system such as 8051-based microcontroller with 128 kbyte ROM.

• International Journal of Automotive Technology
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• 제7권4호
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• pp.469-475
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• 2006

In this paper, an optimal suspension system with preview of the road input is synthesized for a half tracked vehicle. The main goal of this research is to improve the ride comfort characteristics of a fast moving tracked vehicle in order to maintain the driver's driving capability. Several different kinds of preview control algorithms are evaluated with active or semi-active suspension systems. The road information estimated from the motion of the 1st road-wheel is adequate to make the best use of the preview control algorithm for tracked vehicles. The ride-comfort characteristics of the tracked vehicle are more dependent on pitching angular acceleration than heaving acceleration. The pitching motion is reduced by the suspension system with hard outer suspensions and soft inner suspensions. Simulation results show that the performance of sky-hook algorithms for ride comfort nearly follow that of full state feedback algorithms.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.734-735
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• 2008

Shock absorber for rotorcraft landing gear should absorb landing impact during landing and isolate vibration to fuselage during taxiing. Double stage oleo-pneumatic shock absorber is known to have better performances than single stage oleo-pneumatic shock absorber. This paper deals with the z-direction translational acceleration at mass center, roil and pitch angular acceleration of fuselage for single and double stage oleo-pneumatic shock absorber at nose landing gear when a 6DOF rigid model is taxiing on the pound.