• Journal of Ocean Engineering and Technology
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• v.28 no.3
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• pp.209-217
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• 2014

In the present study, the water impact loads on two-dimensional symmetric and asymmetric wedges were mainly studied. The impact pressure and force were measured during a vertical drop of the symmetric and asymmetric wedges. The measured pressure was compared with analytic solutions. The measured force at a local area of the wedge was compared with the integrated pressures and analytic solutions. Some findings on symmetric and asymmetrical wedge drops are presented, and the reliability of the force sensor used for the measurement of the local impact force is discussed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.5
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• pp.359-371
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• 2013

This paper is the first paper among two papers which constitute the paper about the rigid body dynamic analysis on the spent nuclear disposal canister under accidental drop and impact on to the ground. This paper performed the general theoretical study on the rigid body dynamic analysis. Through this study the impulsive force which is occurring in the spent nuclear fuel disposal canister under accidental drop and impact to the ground and required for the structural safety design of the canister is intended to be theoretically formulated. The main content of the theoretical study is about the equation of motion in the multibody dynamics. On the basis of this study the impulsive force which is occurring in the multibody in the case of collision between multibody is theoretically formulated. The application of this theoretically formulated impulsive force to computing the impulsive force occurring in the spent nuclear fuel disposal canister under accidental drop and impact to the ground is investigated.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.1
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• pp.81-89
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• 2017

This study investigates store separation characteristics of an unmanned aerial vehicle having generic stealth configuration over unsteady flow of an internal bay. Free-drop wind tunnel tests are conducted to simulate bomb releases from an internal weapons bay while high-speed camera images are taken. The images are analyzed to examine the effects of flow velocity, angle of attack, flap deflection and the ejector force application on the store separation trajectories. For the free-drop wind tunnel tests, Froude Scaling is applied to match the dynamic similarity for the bomb model, and the ejector force is simulated by using small pneumatic cylinders. The results indicate that the test bomb model safely separates from the internal bay at the given test conditions and configurations. It is also observed that the effects of the flow velocity and ejector force application have greater impacts on the separation trajectories than those of angle of attack and flap deflection.

• 한국가시화정보학회:학술대회논문집
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• 2003.11a
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• pp.111-114
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• 2003

Drop size is one of the most important parameters which are control the performance of the engine using liquid fuel/oxidizer and drop formation is mainly controlled by aerodynamic force caused by ambient gas. Because of this, empirical data and correlation acquired under standard ambient condition are not valid. So experiments under high ambient pressure condition to measure the drop size using image processing method And find the empirical correlation between SMD and chamber pressure(density), injection velocity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1479-1482
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• 2004

LMTT (Linear Motor-based Transfer Technology) is horizontal transfer system in the maritime container terminal for the port automation. The system is driven by PMLSM (Permanent Magnetic Linear Synchronous Motor) that is consists of stator modules on the rail and shuttle car. This paper investigates the effect of the drop height of container on impact reaction force of the Impact Absorber (IA) in shuttle car for LMTT. The results of this investigation are obtained from detailed finite element analysis for various parameters, such as the spring coefficient, the drop height of container.

• Journal of Welding and Joining
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• v.15 no.3
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• pp.36-46
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• 1997

Dynamics of molten drop detachment in the Gas Metal Arc (GMA) welding is investigated using the Volume of Fluid(VOF) method. The electromagnetic effects are included in the formulation of the VOF method which has been widely used to analyze the dynamics of the fluid having a free surface. The molten drop geometry, pressure and velocity profiles within the drop are calculated numerically in the cases of globular and spray transfer modes. It appears that the velocity and current distribution affect metal detachment. It is found that the taper is formed and maintained during the spray transfer by the electromagnetic force. Predicted results show reasonably good agreement with the available experimental data which validates the application of the VOF method to metal transfer analysis.

• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.228-233
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• 2005

Two-dimensional Stokes flows through a micro channel with a couple of symmetric vertical fins are investigated. At far up- and down-stream from the fins, the plane Poiseuille flow exists in the channel. The slip boundary conditions are applied to take account of the Knudsen number effects. For the analysis, the method of eigen function expansion and collocation method are employed. By the results, the streamline patterns and pressure distributions are shown and the force exerted on the fin and the excess pressure drop due to the fins are determined as functions of the length of the fin and Knudsen number. It may be conjectured that the force and the excess pressure drop are almost independent of the Knudsen number.

• 한국가시화정보학회:학술대회논문집
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• 2007.11a
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• pp.128-133
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• 2007

An electrostatic inkjet head can be used for manufacturing processes of large display systems and printed circuit boards (PCB) as well as inkjet printers because an electrostatic field provides an external force which can be manipulated to control sizes of droplets. The existing printing methods such as thermal bubble and piezo inkjet heads have shown difficulties to control the ejection of the droplets for printing applications. Thus, the new inkjet head has been proposed using the electrostatic force. A numerical analysis has been performed to calculate the intensity of the electrostatic field using the Maxwell's equation. Also, experiments have been carried out to investigate the droplet movement using a downward capillary with outside diameter of $500{\mu}m$. Gravity, surface tension, and electrostatic force have been analyzed with high voltages for a drop-on-demand ejection. It has been observed that the droplet size decreases and the frequency of the droplet formation and the velocity of the droplet ejection increase with increasing the intensity of the electrostatic field using high-speed camera.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.117-123
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• 2005

This paper deals with the finite element model of the monitor fur the simulation of directional free drop tests such as the backward and vertex free drop as well as the associated free-drop experiment. The model was made for an unconditional stable solution fur the explicit integration algorithm. It was found through the comparison between simulation and experimental results that the general behaviors at the time of impact were observed to well correlate with each other in terms of acceleration, displacement, contact force and stress of monitor components.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.78-85
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• 2002

This paper deals with the finite element model of the monitor for the simulation of directional free drop tests such as backward, sideward, edge and vertex drop. The model was made for an unconditional stable solution for the explicit integration algorithm. The general behaviors at the time of impact were found to well correlate with the actual situation in terms of acceleration, displacement, contact force and stress of monitor components even though the experiment of the associated drop is performed for the validity of the model.