• Journal of the Microelectronics and Packaging Society
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• v.20 no.1
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• pp.21-26
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• 2013

This study presents new analysis method to predict bending behavior of packaging substrate structure by comparing finite element method simulation and measured curvature using 3D scanner. Packaging substrate is easily bent and deflected while undergoing various processes such as curing of prepreg and copper pattern plating. We prepare specimens with various conditions and measure contours of each specimen and compute the residual stresses on deposited films using analytical solution to find the principle of bending. Core and prepreg in packaging substrate are made up of resin and bundles of fiber which exist orthogonally each other. Anisotropic material properties cause peculiar bending behavior of packaging substrate. We simulate the bending deflection with finite element method and verify the simulated deflection with measured data. The plating stress of electrodeposited copper is about 58 MPa. The curing stresses of solder resist and prepreg are about 13 MPa and 6.4 MPa respectively in room temperature.

• Journal of Mechanical Science and Technology
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• v.20 no.9
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• pp.1371-1381
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• 2006

This paper deals with the active vibration control of a simply-supported beam traversed by a moving mass using fuzzy control. Governing equations for dynamic responses of a beam under a moving mass are derived by Galerkin's mode summation method, and the effect of forces (gravity force, Coliolis force, inertia force caused by the slope of the beam, transverse inertia force of the beam) due to the moving mass on the dynamic response of a beam is discussed. For the active control of dynamic deflection and vibration of a beam under the moving mass, the controller based on fuzzy logic is used and the experiments are conducted by VCM (voice coil motor) actuator to suppress the vibration of a beam. Through the numerical and experimental studies, the following conclusions were obtained. With increasing mass ratio y at a fixed velocity of the moving mass under the critical velocity, the position of moving mass at the maximum dynamic deflection moves to the right end of the beam. With increasing velocity of the moving mass at a fixed mass ratio ${\gamma}$, the position of moving mass at the maximum dynamic deflection moves to the right end of the beam too. The numerical predictions of dynamic deflection of the beam have a good agreement with the experimental results. With the fuzzy control, more than 50% reductions of dynamic deflection and residual vibration of the tested beam under the moving mass are obtained.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1889-1894
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• 2012

A small-scale chamber test laboratory for controlled low strength materials with bottom ash and recycled in-situ soil have been carried out. Laboratory test which was simulated during construction stage was conducted. The vertical deflection of 4.43mm to 6.6mm, and the horizontal deflection of 5.49mm to 15.9 mm were measured during backfilling. In case of loading, the vertical deflection of 2.41mm to 8.69mm, and the horizontal deflection of 1.66mm to 2.53mm were measured. Its residual deflections were 1.40mm to 5.93mm for vertical and 1.66mm to 2.53mm for lateral. The vertical and horizontal deflecto of controlled low strength materials were smaller than that of sand backfill. Also, it was same trend for the measured surface settlement.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.4
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• pp.23-28
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• 1990

This study is to investigate the magnitude, direction and distribution of residual stresses in surface ground plate according to working conditions. The specimens were made of structural carbon steel and were machined in various grinding conditions. These were divided in two groups; heat-treated materials and non-heat-treated materials. In each working condition, let the ground specimen generate displacements using deflection-etching techniques. At the same time, these displacements were precisely measured with electronic micrometer. Through the relation formula between the plane stress and strain, which was derived using these measured data, the values of residual stress are calculated, and the results are analyzed. These results are as follows : 1. According to the working conditions in this experiment, it can be seen that the distribution of residual stress generally had same trend and the maximum residual stress remained in 20~30 ((${\mu}m$) beneath the surface. 2. It is observed that compressive residual stress changes into tensile stress in 5~20 (${\mu}m$) beneath the surface. It is suggested that such phenomenon is originated from the friction effect in grinding process. 3. As the hardness increases by the heat treatment, residual stress increases. 4. As the fatigue strength increases by the compressive residual stress, it is desirable that the dowm feed and table feed reduce. 5. It can be seen that the more great the down feed and table feed increase, the more close the changing point, where the stress changed from compressive to tensile, is colse to the surface. This is due to the resultant effects of the grinding temperature and resistence are larger than the effect of the friction.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.612-614
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• 1997

Silicon based micro mirror array is a highly efficient component for use in optical applications such as adaptive optical systems and optical correlators. A micro mirror array designed, fabricated and tested here is consisted of $5{\times}5$ single layer polysilicon, electrostatically driven actuators. In this paper, deflection characteristics and pull-in behavior of the actuators for analog control was studied and particularly, the influence of the residual stress in flexure beams for the restorative force of actuators was considered. The springs are modeled as a residual stress-free spring and a spring with residual stress. In calculation, a mirror with the residual stress-free springs has 30.3N/m spring constant and 31.1V pull-in voltage. On the other hand, a mirror with the stressed springs has 23.6N/m and 27.4V respectively. The experimental result, which is 20.5N/m and 25.5V, shows that the stressed springs ore well modeled.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.327-327
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• 2007

This paper reports the simulation results of piezoelectric microspeakers due to structural changes(diaphragm materials, corrugation width and electrode shapes). When we compared the dependence of diaphragm material properties, the microspeaker with LTO(Low Temperature Oxide) diaphragm shows higher deflection than that of silicon nitride diaphragm, even though the resonant frequencies are almost same in both cases. In case of circular-electrode microspeaker, the deflection of diaphragm is about $16\;{\mu}m$ at 20 V, and it decreases as the corrugation width is decreased. However, the deflection of diaphragm with the square-electrode reveals almost twice times higher value at the same applied voltage than the circular one, and it increases as the corrugation depths are decreased from $30\;{\mu}m\;to\;10\;{\mu}m$. The first resonant frequency of microspeakers present about 1.8 kHz in circular-electrode and 1.2 kHz in square-electrode, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.34-34
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• 2010

This paper describes effect of the bending deformation of high voltage composite bushing with winding tension. The composite bushing can be formed, by adding silicone rubber sheds to a tube of composite materials. The FRP tube is internal insulating part of a composite bushing and is designed to ensure the mechanical characteristics. Generally the properties of FRP tube can be influenced by the winding angle, wall thickness and winding tension. As winding tension is increased glass contents was increased in the range of 70.4~76.6%. In the bending test, winding tension is increased residual deflection was decreased in the range of 14.0~12.2 mm.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.67.3-67
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• 2001

A fuzzy control strategy is described which is utilized to control the joint angle and tip deflection in single flexible manipulator. In this paper, an existing model for a single flexible manipulator is used f3r the initial development of an FLC. One FLC is designed to govern the joint angle of the manipulator as it is rotated from one position to another, and a second FLC is designed to attenuate the tip deflection which result from joint angle body motion. Reference Trajectory Command is an important method to reduce vibration in flexible beam. This paper presents a very simple command control shaping which eliminates multiple mode residual vibration in a flexible beam combined fuzzy controller ...

• Proceedings of the Korea Concrete Institute Conference
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• 1992.04a
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• pp.143-147
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• 1992

Description of the behavior of the R.C structural members fixed on massive concrete is not normally generalization of recognized configuration for regular R.C. design guidanes. This can be due to the complexity of evaluation of internal resistancy and deflection changes of the members subjected to the various external forces. On the base of axially loaded member fixed on footing, however, the estimation of deflection changes due to flexural force shear force and rotational force is to be carried out in ways of specifying the bond characteristics of axial bars embedded in massive concrete. This work is to quantify adhesion of steel-concrete, initial concrete cracking stress near bar rib, maximum bond stress and residual stress in concrete respectively. In addition to quantification of them for particulate behavior, the suggestions of multi-linear bond stress-slip diagram made in carrying out finite element analyses for adhesion failure, examining concrete cracking status and reviewing existing experimental data lead to alternatively constructed relationship between bond stress and slip for a axial bars embedded massive concrete.

• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1075-1079
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• 2001

The R-curve for in situ-toughened SiC-30 wt% TiC composites was estimated by the indentation-strength method and compared to that of monolithic SiC with toughened microstructure. Both materials exhibited rising R-curve behavior. The SiC-TiC composites, however, displayed better damage tolerance and higher resistance to crack growth. Total volume fractions of SiC key grains, which take part in toughening mechanisms such as crack bridging and crack deflection, were 0.607 for monolithic SiC ceramics and 0.614 for SiC-TiC composites. From the microstructural characterization and the residual stress calculation, it was inferred that this superior performance of SiC-TiC composites can be attributed to stress-induced microcracking at heterophase (SiC/TiC) boundaries and some contribution from carck deflection by TiC grains.