• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.573-576
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• 2005

This research presents a three-dimensional modeling technique for a flexible sheet. A relative coordinate formulation is used to represent the kinematics of the sheet. The three-dimensional flexible sheet is modeled by multi-rigid bodies interconnected by out-of-plane joints and plate force elements. A parent node is designated as a master body and is connected to the ground by a floating joint to cover the rigid motion of the flexible sheet in space. Since the in-plane deformation of a sheet such as a paper and a film is relatively small, compared to out-of-plane deformation, only the out-of-plane deformation is accounted for in this research. The recursive formulation has been adopted to solve the equations of motion efficiently. An example is presented to show the validity of the proposed method.

• Journal of the Korean Society of Safety
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• v.23 no.3
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• pp.42-50
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• 2008

This study, push-off tests for the initially uncracked specimens were conducted to investigate shear transfer mechanism in reinforce concrete elements. Experimental programs for shear transfer were undertaken to investigate the effect of the concrete compressive strength, the presence of steel stirrups as shear reinforcement and the amount of steel stirrups. As the shear plane is loaded, several cracks form in a direction inclined to the shear plane, creating compression struts in the concrete. For this stage, shear is being transferred through a truss-like action produced by the combination of the compressive force in the concrete struts and the tensile force that the steel reinforcement crossing the shear plane develops. In the normal strength concrete specimens with steel stirrups, ultimate failure occurred when the compression struts crushed in concrete. In the high strength concrete specimens, on the other hand, ultimate failure occurred when the steel stirrups developed their yield strength.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.513-518
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• 1998

In Half Precast Concrete Method, such as composite slab and composite wall, Interface between half PC plate and cast-in-place concrete is occurred. And this interface endure lastly in-plane shear which is occurred by external force. Therefore, test was executed to study in-plane shear strength of interface between half PC plate and cast-in-place concrete. In this test, Experimental parameters are finishing condition of the interface, cohesion of concrete, existence and nonexistence of re-bar truss, and angle and direction of lattice of re-bar truss. Comparing and analyzing experimental results, conclusions are obtained as follows. (1) In-plane shear strength of wide interface in composite plate is more affected by the roughness of interface than re-bar truss. And cohesion of concrete contribute to increasing in-plane shear strength. Therefore it seems that the interface should be roughen and kept clean to improve in-plane shear strength. (2) It seems that shear friction equation in ACI code can be sagely available for design of in-plane shear of composite plate.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.225-260
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• 2002

The purpose of this paper is to further extend the theoretical understanding of the dynamic end milling process and to derive a computational model to predict the milling force components. A comparative assessment of different cutting force models is performed to demonstrate that the instantaneous shear plane based formulation is physically sound and offers the best agreement with experimental results. The procedure for the calculation of the model parameters used in the cutting force model, based on experimental data, has been presented. The validity of the proposed computational model has been experimentally verified through a series of cutting tests.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.8
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• pp.1631-1637
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• 2002

This paper presents a method for calculating contact force between bodies on plane. At each integration time step, the proposed method finds expected contact point on their outlines and then calculates penetration, velocity of penetration and contact force. This paper adopts continuous analysis method and multi-point contact method to calculate contact force. To obtain the accurate expected contact point on their outlines, a new algorithm is developed. The accuracy of the proposed algorithm is demonstrated by comparing the numerical results of the proposed method and DADS.

• Korean Journal of Computational Design and Engineering
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• v.3 no.3
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• pp.161-167
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• 1998

Cutting forces in ball-end milling of slanted surfaces are calculated. The cutting area is determined from the Z-map of the surface geometry and current cutter location. The obtained cutting area is projected onto the cutter plane normal to the Z-axis and compared with cutting edge element location. Cutting force is calculated by integration of elemental cutting forces of engaged cutting edge elements. Experiments with various slanted angles were performed to verify the proposed cutting force estimation model. It is shown that the proposed method predicts cutting force effectively for any geometry including sculptured surfaces with cusp marks and surfaces with pockets and holes.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.2
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• pp.179-186
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• 2012

The potential hazards resulting from a low-velocity impact(bird-strike, tool drop, runway debris, etc.) on aircraft structures, such as engine nacelle or leading edges has been a long-term concern to the aircraft industry. Certification authorities require that exposed aircraft components must be tested to prove their capability to withstand low-velocity impact without suffering critical damage. In most of the past research studies unloaded specimens have been used for impact tests, however, in reality it is much more likely that a composite structure is exposed to a certain stress state when it is being impacted, which can have a significant effect on the impact performance. And the radiated impact sound induced by impact is analyzed for the damage detection evaluation. In this study, an investigation was undertaken to evaluate the effect in-plane loading on the impact force and sound of composite laminates numerically.

• Structural Engineering and Mechanics
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• v.81 no.5
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• pp.591-606
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• 2022

When the friction pendulum system and shear keys work together to resist the ground motion, which inclined inputs (non 45°) to the bridge structure, the shear keys in XY direction will be sheared asynchronously, endowed the friction pendulum system with a violent curvilinear motion on the sliding surface during earthquakes. In view of this situation, firstly, this paper abandons the equivalent linearization model of friction and constructs a Spring-Coulomb friction plane isolation system with XY shear keys, and then makes a detailed mechanical analysis of the movement process of friction pendulum system, next, this paper establishes the mathematical model of structural time history response calculation by using the step-by-step integration method, finally, it compiles the corresponding computer program to realize the numerical calculation. The results show that the calculation method in this paper takes advantage of the characteristic that the friction force is always µmg, and creatively uses the "circle making method" to express the change process of the friction force and resultant force of the friction pendulum system in any calculation time step, which can effectively solve the temporal nonlinear action of the plane friction; Compared with the response obtained by the calculation method in this paper, the peak values of acceleration response and displacement response calculated by the unidirectional calculation model, which used in the traditional research of the friction pendulum system, are smaller, so the unidirectional calculation model is not safe.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.6
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• pp.1010-1017
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• 2013

Two-axial electrodynamic forces generated on a conductive plate by a partially shielded magnet wheel are strongly coupled through the rotational speed of the wheel. To control the spatial position of the plate using magnet wheels, the forces should be handled independently. Thus, three methods are proposed in this paper. First, considering that a relative ratio between two forces is independent of the length of the air-gap from the top of the wheel, it is possible to indirectly control the in-plane position of the plate using only the normal forces. In doing so, the control inputs for in-plane motion are converted into the target positions for out-of-plane motion. Second, the tangential direction of the open area of the shield plate and the rotational speed of the wheel become the new control variables. Third, the absolute magnitude of the open area is varied, instead of rotating the open area. The forces are determined simply by using a linear controller, and the relative ratio between the forces creates a unique wheel speed. The above methods were verified experimentally.

• Journal of the Korean Ceramic Society
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• v.14 no.4
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• pp.226-229
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• 1977

The infrared absorption spectrum of Synthesized magnesite is shown in the wve number region 2510 and 745cm-1. By using Wilson's GF matrices the force constants' of the Urey-Bradley force field were deterined from the infrared absorption frequencies. For magnesite the stretching force constant K=5.41, the bending force constant H=0.46, the repulsive force constant F=1.97, and the force constant for the out-of-plane vibration fθ=0.65md/Å. For calcite they are K=5.51, H=0.38, F=1.88 and fθ=0.64md/Å.