• Journal of the Korean Society for Nondestructive Testing
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• v.12 no.2
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• pp.21-29
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• 1992

Acceleration signal characteristics of a steel plate, impacted by steel balls, were studied in an attempt to apply the experimental results to the impact location and mass estimation of metallic loose parts in the cooling system of nuclear power plants. Experimental results show that the variation of maximum acceleration amplitude and impact contact time due to the change of ball mass and impact velocity can be well explained by the Hertz impact theory. The frequency spectral pattern shifted slightly in spite of the increase of impact velocity and impact location. Ball mass, however, strongly affected the frequency spectral pattern. Hence the frequency spectrum can be used for estimation of the mass of unknown loose parts in the cooling system.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.58-65
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• 2003

The seismic response analysis of a freestanding spent fuel storage cask model are performed for an artificial time history acceleration generated by the basis on the US NRC RG1.60 response acceleration spectrum. This paper focuses on the structural stability by seismic loads to check the overturing possibility of storage cask and the slipping displacement on bed. Parametric analyses of a simplified cask model are performed to take into account the variations in seismic load magnitude and cask/bed interface friction. The analyses results show that the storage cask has a large marginal integrity in the response acceleration and slipping distance for both design seismic and beyond design seismic loads.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.536-542
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• 2008

The rocket technology has the best reliability and the high acceleration performance currently. In addition, next generation propulsion system is acquired to low cost and high payload percentage at that same time. This work is to improve the performance of Diskshaped MHD accelerator which is expected as the one of the solution. In this study we have been focusing on the swirl vane. It is so important to know that how the swirl vane contribute the plasma and its performance. As results, the gas velocities of r-component with inlet swirl were increased about over 3000m/s at the channel exit. And then static gas pressure were also reduced, we found that the case with inlet swirl gives the good influence to the acceleration performance. And the difference of the acceleration by positive and negative inlet swirl is that gas velocity of $\theta$-component may operate to the electric field.

• Journal of Auto-vehicle Safety Association
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• v.11 no.3
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• pp.37-42
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• 2019

This paper presents an autonomous acceleration planning algorithm for pedestrian collision avoidance at urban. Various scenarios between pedestrians and a vehicle are designed to maneuver the planning algorithm. To simulate the scenarios, we analyze pedestrian's behavior and identify limitations of fusion sensors, lidar and vision camera. Acceleration is optimally determined by considering TTC (Time To Collision) and pedestrian's intention. Pedestrian's crossing intention is estimated for quick control decision to minimize full-braking situation, based on their velocity and position change. Feasibility of the proposed algorithm is verified by simulations using Carsim and Simulink, and comparisons with actual driving data.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1904-1909
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• 1991

Software linear and exponential acceleration/deceleration algorithms for control of machine axes of motion in industrial robots and CNC machine tools are proposed. Typical hardware systems used to accelerate and decelerate axes of motion are mathematically analyzed. Discrete-time state equations are derived from the mathematical analyses for the development of software acceleration/deceleration algorithms. Synchronous control method of multiple axes of motion in industrial robots and CNC machine tools is shown to be easily obtained on the basis of the proposed acceleration/deceleration algorithms. The path error analyses are carried out for the case where the software linear and exponential acceleration/deceleration algorithms are applied to a circular interpolator. A motion control system based on a floating point digital signal processor (DSP) TMS 320C30 is developed in order to implement the proposed algorithms. Experimental results demonstrate that the developed algorithms and the motion control system are available for control of multiple axes and nonlinear motion composed of a combination of lines and circles which industrial robots and CNC machine tools require.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.603-610
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• 1998

This paper develops a 7 DOF vehicle model to study the effects of the active suspension on ride. The model is used to derive a control law for the active suspension using a full state linear optimal control technique. A wheelbase preview type active suspension is also considered in the control law derivation. The time delay between wheelbases is approximated using Pade approximation technique. The ride model is extended to a 14 DOF handling model. The 14 DOF handling model includes lateral, longitudinal, yaw and four wheel spin motions in addition to the 7 DOF ride model. A control law which is derived considering only ride related parameters is used to study the effects of the active suspension on a vehicle handling. J-turn maneuver simulation results show that the active suspension has a slower response in lateral acceleration and yaw rate, a bigger steady state lateral acceleration and an oversteer tendency. Lane changing maneuver simulation results show that the active suspension has a little bigger lateral acceleration but a much smaller roll angle and roll motion. Braking maneuver simulation results show that the active suspension has a much smaller pitch angle and pitch motion.

• Journal of The Korean Astronomical Society
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• v.36 no.spc1
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• pp.63-73
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• 2003

Solar flares present a number of radiative characteristics indicative of kinetic processes of high energy particles. Proper understanding of the kinetic processes, however, relies on how well we can separate the acceleration from transport characteristics. In this paper, we discuss microwave and hard X-ray bursts as a powerful tool in investigating the acceleration and transport of high energy electrons. After a brief review of the studies devoted to the kinetic process of solar flare particles, we cast them into a simple formulation which allows us to handle the injection, trap, and precipitation of flare electrons self-consistently. The formulation is then taken as a basis for interpreting and analyzing a set of impulsive and gradual bursts occurred on 2001 April 6 observed with the Owens Valley Solar Array, and HXT/WBS onboard Yohkoh satellite. We quantify the acceleration, trap, and precipitation processes during each burst in terms of relevant time scales, and also determine ambient density and magnetic field. Our result suggests that it should be the acceleration property, in particular, electron pitch angle distribution, rather than the trap condition, that is mainly responsible for the distinctive properties of the impulsive and gradual flares.

• Journal of Ocean Engineering and Technology
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• v.34 no.3
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• pp.202-207
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• 2020

A track-type underwater construction robot (URI-R) was developed by the Korea Institute of Ocean Science & Technology. Because URI-R uses tracks to move on the seabed, insufficient ground strength may hinder its movement. For smooth operation of URI-R on the seabed, it is important to determine the geotechnical properties of the seabed. To determine these properties, standard penetration test (SPT), cone penetration test (CPT), and sampling are used on land. However, these tests cannot be applied on the seabed due to a high cost owing to the vessel, crane, sampler, and analysis time. To overcome these problems, a free fall cone penetration tester (FFCPT) is being developed. The FFCPT is a device that acquires the geotechnical properties during impact/penetration/finish phases by free fall in water. Depth information is crucial during soil data acquisition. As the FFCPT cannot measure the penetration depth directly, it is estimated indirectly using acceleration. The estimated penetration depth was verified by results of real tests conducted on land.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.6
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• pp.476-482
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• 2014

The stress analysis of the pipeline is required in any kind of plant for its safe operation. For this, the displacement vibration data measured at many locations of the pipeline should be provided. In reality, the installation of the non-contact type displacement sensors such as laser displacement sensors or eddy current type proximity sensors in a narrow and confined region in the vicinity of the pipeline is almost impracticable. In this work, the general purpose piezo-ceramic accelerometers were attached on the measuring points on the pipeline and the acceleration vibration signal was acquired. The measured acceleration signal was low pass filtered and then downsampled. The resulting acceleration signal was transformed into both the time-domain and frequency-domain displacement signal utilizing the fast Fourier transform techniques. All the procedures are presented in detail. It is demonstrated that the measurement of the pipeline acceleration by using contact type accelerometers can be made for the purpose of providing the required displacement data for the stress analysis of the pipeline.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.5
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• pp.478-485
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• 2015

Availability of the climbing angle information is crucial for the intelligent vehicle system. However, the climbing angle information can't be measured with the sensor mounted on the vehicle. In this paper, climbing angle estimation system is proposed. First, longitudinal acceleration obtained from gyro-sensor is compared with the actual longitudinal acceleration of the vehicle. If the vehicle is in yawing motion, actual longitudinal acceleration can't be approximated from time derivative of wheel speed, because lateral velocity and yaw rate affect actual longitudinal acceleration. Wheel speed and yaw rate can be obtained from the sensors mounted on the vehicle, but lateral velocity can't be measured from the sensor. Therefore, lateral velocity is estimated using unknown input observer with nonlinear tire model. Simulation results show that the compensated results using lateral velocity and yaw rate show better performance than uncompensated results.