• 대한임베디드공학회논문지
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• 제16권6호
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• pp.285-292
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• 2021

Autonomous vehicles are divided into an upper controller that calculates control value through cognitive judgment and a lower controller that appropriately transmits its control value to an actuator. Here, the longitudinal control in a lower controller has a problem as the road slopes due to the property of the Acceleration sensor to output the acceleration as the slope of the device. Therefore, in this paper, a sigmoid function is proposed to determine the slope to compensate for this problem. Through the experiment, Checked performance by comparing the existing table model with the proposed model.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.237-238
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• 2010

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.613-617
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• 2001

The longitudinal vibration of an axially moving membrane is studied when the membrane has translating acceleration. The equation for the longitudinal vibration is linear and coupled, The equation for the longitudinal vibration are discretized by using the Galerkin approximation after they are transformed into the variational equations, i.e., the weak forms so that the admissible function can be used for the bases of the longitudinal deflection. With the discretized equations for the longitudinal vibration, the time responses are investigated by using newmark method.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.361-364
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• 1997

The re-enty guidance design involves trajectory optimization, generation of a reference drag acceleration profile with the satisfaction of trajectory constraints. This reference drag acceleration profile can be considered as the reference trajectory. This paper proposes the atmospheric re-entry system which is composed of longitudinal, later and range control. This paper shows the a performance of a re-entry guidance and control system using feedback linearization control and predictive control.

• 한국ITS학회 논문지
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• 제22권6호
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• pp.284-298
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• 2023

자율주행 기술이 빠르게 발전함에 따라 자율주행 기술을 직·간접적으로 체험할 수 있는 기회가 대중에게 제공되고 있지만, 이용자 관점에서 편안한 승차감을 기대할 수 있는 선호하는 자율주행 패턴에 대해서는 연구가 미비하다. 본 연구에서는 주행 시뮬레이터와 자율주행이 가능한 실험차를 활용하여 종·횡방향 가속도에 대한 이용자 측면 만족도 평가를 수행하였다. 주행 실험을 통하여 도출한 5가지 종·횡방향 가속도 값을 활용하여 자율주행 패턴을 가상환경 시뮬레이션으로 구현하였으며, 그 중 3가지 값에 대해서는 실차 기반 자율주행으로 구현하여 만족도 및 불안감 수준 평가실험을 추가 진행하였다. 연구 결과, 실험 참가자들은 종방향 가속도에 비하여 횡방향 가속도에 더 민감한 평가를 하였으며, 불안감 수준도 높게 나타나는 것을 확인할 수 있었다. 이러한 결과를 바탕으로 이용자 측면 자율주행 패턴 평가연구 필요성과, 시뮬레이터 기반 평가방법의 적정성을 제시하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 창립기념 춘계학술대회 논문집
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• pp.556-563
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• 1998

Railway bridges have a significant effect on the stress and displacement of continuous welded rail(CWR). Longitudinal compression force at high temperature, combined breaking or acceleration forces can introduce track buckling. On the other hand, longitudinal tensile forces, associated with low temperatures, in combination with breaking forces may break rail. Therefore, it is very important to work out thorough counter measures for those problems, specially in high speed rail which high safety is required. The exact evaluation of longitudinal force of rail has the key to the solution. The main aim of the present paper is to examine whether the longitudinal force of CWR's on Kyung-Bu-HSR satisfy the criteria to be fulfilled in the design of railway bridge. The analyses are carried out by using "CWRAP" program which was developed by our research group. The ballast resistance and breaking force effects on the longitudinal force of CWR are investigated.

• 소음진동
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• 제10권5호
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• pp.838-842
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• 2000

The vibration of an axially moving string is studied when the string has geometric non-linearity and translating acceleration. Based upon the von karman strain theory, the equations of motion are derived considering the longitudinal and transverse deflection. The equation for the longitudinal vibration is linear and uncoupled, while the equation for the transverse vibration is non-linear and coupled between the longitudinal and transverse deflections. These equations are discretized by using the Galerkin approximation after they are transformed into the variational equations, i.e. the weak forms so that the admissible and comparison functions can be used for the bases of the longitudinal and transverse deflections respectively. With the discretized nonlinear equations, the time responses are investigated by using the generalized-$\alpha$ method.

• International Journal of Railway
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• 제2권4호
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• pp.152-163
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• 2009

In this paper, the correlation between the accelerations measured at the track components and the parameters affecting the acceleration is analyzed. To do it, the accelerations of each track component such as rails, sleepers and ballast are measured in Kyong-Bu high-speed Line. The RMS values of the measured accelerations are calculated and the pad stiffness, the longitudinal irregularity, running velocity and the corrugation, are considered as the parameters affecting the acceleration. By using the linear regression, the correlation coefficients are calculated to analyze the relationship between the acceleration characteristics and the parameters. Also, the 1/3 Octave analysis is calculated to analyze the dominant frequency band of the accelerations of the track components.

• 한국공작기계학회논문집
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• 제17권3호
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• pp.47-52
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• 2008

The force transducer in the acceleration plant due to dynamic fracture is calibrated by dynamically using the stress pulses from a longitudinal bar. The bar is supported by two strings attached to the ceiling. The bar velocities before and after impact are measured and a full bridge at bar and transducer is formed by the four strain gauges. A transient recorder is used to store the stress pulse signals of force transducer and bar. For the first test series, three point bend test specimens can be chosen by means of test rig design and the inspection as sample experiment in this presented paper is sufficient for proving with the numerical simulation of the specimen model.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 창립기념 춘계학술대회 논문집
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• pp.502-509
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• 1998

The scheme to reduce jerking phenomena in one push-pull type trainset was proposed. To simulate the jerking between coaches, dynamic analysis model was made. This model could analyze longitudinal dynamic behavior between locomotives and coaches caused by spring and damping characteristics of couplers and center pivots; characteristic curves of traction and braking. To validate the analysis results, tests were conducted in the same driving and braking condition. Comparison of longitudinal acceleration between simulation and test results shows a good agreement. To minimize the jerking phenomena, lots of dynamic simulations were conducted with varying driving/braking effort curve. From the results of simulations, an efficient and economic way to reduce jerking phenomena was found to be to reduce slope of tractive effort curve and synchronize braking time between locomotives and coaches. Test results show that this way could reduce the jerking Phenomena. To express jerkins Phenomena quantitatively, maximum peak to peak values of acceleration were used.