• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.293-296
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• 2002

This work presents the reconstruction of impact force produced by the collision between two elastic structures. The 2-DOF impactor was designed. The shape control of impact farce using correlations of the dynamic characteristics and impact force history between two elastic structures is accomplished. The effects of the relative motion between impactor and elastic structure on the impact force shape are studied. Reconstruction characteristics of impact force in cantilever beam are reviewed.

• Journal of KSNVE
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• v.10 no.3
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• pp.474-479
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• 2000

Piston slap is not only one of the major sources of noise and vibration in internal combustion engines but also a cause of the deterioration of engine performance. The basic mechanism associated with the piston slap seems to be quite simple but the phenomenon is in fact complicated with regard to many mechanical elements associated, First of all the impact force of piston slap must be identified to estimate engine block surface vibration, In this paper model of collision point is proposed to calculate the impact force when slap surface vibration. In this paper model of collision point is proposed to calculate the impact force when slap occurs. The parameters of the model are estimated by employing the concept of point mobility, . The predicted and experimentally observed vibration results confirm that the proposed method is practically useful.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.416-419
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• 2004

The kinetic energy during ship collision with bridge piers is released as the permanent deformations of structure and friction between the impact surfaces. So the ship collision energy is estimated from the equations of motions for ship-pier collisions which include the influence of the surrounding water, different impact angles and impact locations. The normal impact energy and tangent impact energy at a collision location and angle can be transformed into the normal impact force and friction force acting on the structure. Also the kinetic energy after collisions is calculated from the linear and angular impulse of ship collisions. The collision energy absorption system such as the protective structures for bridges is designed by evaluating the damage portions of ship and structure during the ship-structure collisions varying from the soft impact to hard impact and then the estimation of it will be suited for the design of protective measures.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.5
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• pp.469-481
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• 2016

In this paper, a mathematical methodology was theoretically studied to obtain the impact force caused by the collision between rigid bodies. This theoretical methodology was applied to compute the impact force applied on the spent nuclear fuel disposal canister that accidentally drops and collides onto the ground. From this study, the impact force required to ensure a structurally safe canister design was theoretically formulated. The main content of the theoretical study concerns the rigid body kinematics and equation of motion during collision between two rigid bodies. On the basis of this study, a general impact theory to compute the impact force caused by the collision between two bodies was developed. This general impact theory was applied to theoretically formulate the approximate mathematical solution of the impact force that affects the spent nuclear fuel disposal canister that accidentally falls to the ground. Simultaneously, a numerical analysis was performed using the computer code to compute the numerical solution of the impact force, and the numerical result was compared with the approximate mathematical solution.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.6
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• pp.469-477
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• 2012

This paper describes the characteristic analysis of ice impact force for the Arctic structure shape. In the present study an energy method has been used to predict the impact force during the ice-structure collision. This study also employs two concepts for reference contact area and normalized stress in analysis procedure. The influences of factors, such as impact velocity, full penetration depth, structure shape and ice floe size, are investigated. Full penetration occurs, particularly at lower impact velocity when ice thickness increase. But "typical size" ice floe does not expected ever to achieve full penetration during the impact procedure. The structure shape is the dominant factor in ice impact force characteristic. The results for various ice-structure collision scenarios are analyzed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.376-382
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• 2007

A Collapse of bridge by ship's collision to the bridge post may lead a great calamity. This paper investigates on avoiding collision between a ship and bridge by improvement of environmental factors, submitting a counter plan of reducing collision effect by triangular type of collision protecting bar and ship maneuvering skills. Putting up collision protecting bar fences of triangular type around the bridge posts would decrease the collision impact force by 75 percent.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.175-183
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• 2022

The collision between a ship and bridge across a waterway may result in extremely serious consequences that may endanger the safety of life and property. Therefore, factors affecting ship bridge collision must be investigated, and the impact force should be discussed based on various collision conditions. In this study, a finite element model of ship bridge collision is established, and the peak impact force of a ship bridge collision based on 50 operating conditions combined with three input parameters, i.e., ship loading condition, ship speed, and ship bridge collision angle, is calculated via numerical simulation. Using neural network models trained with the numerical simulation results, the prediction model of the peak impact force of ship bridge collision involving an extremely short calculation time on the order of milliseconds is established. The neural network models used in this study are the basic backpropagation neural network model and Elman neural network model, which can manage temporal information. The accuracy of the neural network models is verified using 10 test samples based on the operating conditions. Results of a verification test show that the Elman neural network model performs better than the backpropagation neural network model, with a mean relative error of 4.566% and relative errors of less than 5% in 8 among 10 test cases. The trained neural network can yield a reliable ship bridge collision force instantaneously only when the required parameters are specified and a nonlinear finite element solution process is not required. The proposed model can be used to predict whether a catastrophic collision will occur during ship navigation, and thus hence the safety of crew operating the ship.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.7 s.112
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• pp.754-761
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• 2006

This paper presents the dynamic characteristics of MR impact damper for vehicle collision system. Various types of mechanism have been proposed to reduce force transmitted to the vehicle chassis and finally to protect occupants from injury. In the case of head-on collision, the bumper makes main role of isolation material for collision attenuation. In this study, the proposed bumper system consists of MR impact damper and structures. The MR impact damper utilizes MR fluid which has reversible properties with applied magnetic field. The MR fluid operates under flow mode. The bellows is used for generation of fluid flow. A mathematical model of the MR impact damper is derived incorporating with Bingham model of the MR fluid. Field dependent damping force is investigated with time and frequency domain. The MR impact damper is then incorporated with vehicle crash system. The governing equation of motion of vehicle model is formulated considering occupant model. Dynamic characteristics of vehicle collision system investigated with computer simulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.147-152
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• 2006

This paper presents the dynamic characteristics of MR impact damper for vehicle collision system. Various types of mechanism have been proposed for reduce transmitted force to vehicle chassis and finally protect occupants from injury. In the case of frontal collision, the bumper make main role of isolation material for collision attenuation. In this study, proposed bumper system composed of MR impact damper and structures. The MR impact damper is to adopted MR fluid which has reversible properties with applied magnetic field. MR fluid operates under flow mode with Bingham flow and bellows is used for generation of fluid flow. Mathematical model of MR impact damper incorporated with MR fluid is established. Field dependent damping force is investigated with time and frequency domain. The MR impact damper is then incorporated with vehicle crash system. The governing equation of motion of vehicle model is formulated considering occupant model. Dynamic characteristics of vehicle collision system investigated with computer simulation.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.590-595
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• 2020

In this study, the small-scale collision experiments using a pendulum principle were carried out to evaluate the safety of the reinforced concrete building selected as a tsunami evacuation building due to the collision of the waterborne debris represented by ships. The experimental parameters were set as impact velocity, mass and length of the drifted ship. In this paper, the maximum impact force, impact duration, impact waveform and restitution coefficient affecting building response were investigated in detail. As a result, the impact force waveforms were distributed as a triangle in most of the experimental results, but became closer to a trapezoid as the length of the collision specimen increased. This is the very important result in calculating the momentum (impact waveform area) affecting building response, Furthermore, the restitution coefficients were constant regardless of the impact velocity, but they varied depending on the mass and length of the waterborne debris. However, the restitution coefficient for the mass per unit length of the waterborne debris can be evaluated.