• Interaction and multiscale mechanics
• /
• v.1 no.2
• /
• pp.231-250
• /
• 2008

The statistical two-order and two-scale method is developed for predicting the mechanics parameters, such as stiffness and strength of core-shell particle-filled polymer composites. The representation and simulation on meso-configuration of random particle-filled polymers are stated. And the major statistical two-order and two-scale analysis formulation is briefly given. The two-order and two-scale expressions for the strains and stresses of conventionally strength experimental components, including the tensional or compressive column, the twist bar and the bending beam, are developed by means of their classical solutions with orthogonal-anisotropic coefficients. Then a new effective mesh generation algorithm is presented. The mechanics parameters of core-shell particle-filled polymer composites, including the expected stiffness parameters, minimum stiffness parameters, and the expected elasticity limit strength and the minimum elasticity limit strength, are defined by means of the stiffness coefficients and elasticity strength criterions for core, shell and matrix. Finally, the numerical results for predicting both stiffness and elasticity limit strength parameters are compared with the experimental data.

• Computers and Concrete
• /
• v.21 no.3
• /
• pp.335-344
• /
• 2018

More and more special-shaped structural systems have been widely used in various industrial and civil buildings in order to satisfy the new structural system and the increasing demand for architectural beauty. With the popularity of the special-shaped structure system, its seismic performance and damage form have also attracted extensive attention. In the current research, an experimental analysis of six groups of (2/3 scale) T-shaped column joints was conducted to investigate the seismic performance of T-shaped column joints. Effects of the beam cross section, transverse stirrup ratio and axial compression ratio on bearing capacity and energy dissipation capacity of column joints were obtained. The crack pattern of T-shaped column joints under low cyclic load was presented and showed a reversed "K" mode. According to the crack configurations, a tensile-shear failure model to determine the shear bearing capacity and crack propagation mechanisms is developed.

• Steel and Composite Structures
• /
• v.19 no.1
• /
• pp.153-171
• /
• 2015

Twelve large-scale composite deck slabs were instrumented and tested in a cantilever diaphragm configuration to assess the effect of fibers and welded wire mesh (WWM) on the in-plane shear capacity of composite deck slabs. The slabs were constructed with reentrant decking profile and reinforced with different types and dosages of secondary reinforcements: Conventional welded wire mesh (A142 and A98); synthetic macro-fibers (dosages of $3kg/m^3$ and $5.3kg/m^3$); and hooked-end steel fibers with a dosage of $15kg/m^3$. The deck orientation relative to the main beam (strong and weak) was also considered in this study. Fibers and WWM were found efficient in distributing the applied load to the whole matrix, inducing multiple cracking, thereby enhancing the strength and ductility of composite deck slabs. The test results indicate that fibers increased the slab's ultimate in-plane shear capacity by up to 29% and 50% in the strong and weak directions, respectively. WWM increased the ultimate in-plane shear capacity by up to 19% in the strong direction and 9% in the weak direction. The results suggest that discrete fibers can provide comparable diaphragm behavior as that with the conventional WWM.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.30 no.2
• /
• pp.11-19
• /
• 2016

By incorporating a polarization-diversity loop configuration, we have demonstrated the inline switching of transmission and reflection spectra of one of two short-period fiber gratings (SPFGs) with different resonance wavelengths without reconfiguring the filter structure. The proposed filtering apparatus consists of a fiber-pigtailed polarization beam splitter, two SPFGs, and three quarter-wave plates (QWPs). The proposed filter can independently choose the transmission or reflection spectrum of each SPFG through the appropriate adjustment of the orientation angles of the QWPs within the filter without additional optical switches and couplers. The average insertion loss, band rejection ratio, and side-mode suppression ratio of the fabricated filter were measured as ~4.59, ~17.88, and ~19.67dB, respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.1000-1004
• /
• 1995

In the case of the external cylindrical grinding machine, the grinding mechanism can cause a wheel to vibrate due to a wheel cutter. This phenomena will bring about the unsymmetric wear up to high frequency without any relation of rotational speed. So far, when the grinding spindle is analyzed, it is assumed that a wheel is considered as lumped mass at the endof a beam. Nowadays, there is a tendency to use the wheel with a lsrge diameter or CBN wheel to achieve the high speed and accuracy grinding performance. Therefore, this kind of assumption is no longer valid. At the analysis of the grinding spindle, the parameter which dapends on the dynamic characteristics is a combination force between each part. For example, there is the tightness torque of a bolt and taper element in the grindle. In addition, the material property of the wheel can contribute the dynamic characteristics. This paper shows the mode participation of the shell mode of the wheel in the grindle and the dynamic characteristics according to the parameters which are the configuration of the flange and tightness torque of a bolt and taper. Modal parameter of the wheel, flange and the spindle can be extracted through frequency response function obtained by modal test. After that, by changing the tightness torque and kinds of wheel, we could accomplish the test in the whole combined grinding spindle. To perform modal analysis of vibration characteristics in the grinding spindle, we could develop the model of finite element method.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.6
• /
• pp.509-516
• /
• 2007

Mathematical modeling and vibration control of a tiltrotor aircraft composite wing-rotor system are investigated in this study. A wing-mounted rotor can be tilted from the vertical position to a horizontal one, and vice versa. Effect of vibration control of the wing-rotor system via piezoelectricity is studied as a function of tilt angle, ply angle of composite wing and rotor's spin speed. Composite wing is modeled as a thin-walled box beam having a circumferentially uniform stiffness configuration that produces elastic coupling between flap-lag and between extension-twist behavior. Numerical simulations are provided and pertinent conclusions are outlined.

• Proceedings of the KIEE Conference
• /
• 2008.10a
• /
• pp.163-164
• /
• 2008

Chalcogenide glass has been known for many photo induced phenomena and superial electron / optical specific by structure flexibility, unique electronic configuration. It is become known to the greatest specific as photonic material medium that possible to perfect controlling by continuity and photo inducing direction of amorphous chalcogenide. In our experiment, we choose the amorphous As-Ge-Se-S and corning glass as a substrate. And then we have evaporated in the ${\sim}2{\times}10^{-6}$ Torr using a E-beam evaporator, completed thin film sample that have 1um thickness of As-Ge-Se-S in $600{\AA}$, $10{\sim}5{\AA}/s$. At first, we let the change the angle between laser and sample by holography litho method and then, expect that satisfied conclusion which 2-dimension diffraction lattice manufacture and specifics by investing a He-Ne laser for 2000 seconds.

• Computers and Concrete
• /
• v.18 no.1
• /
• pp.17-37
• /
• 2016

This paper compares the arc-length and explicit dynamic solution methods for nonlinear finite element analysis of prestressed concrete members subjected to monotonically increasing loads. The investigations have been conducted using an L-shaped, prestressed concrete spandrel beam, selected as a highly nonlinear problem from the literature to give insight into the advantages and disadvantages of these two solution methods. Convergence problems, computational effort, and quality of the results were investigated using the commercial finite element package ABAQUS. The work in this paper demonstrates that a static analysis procedure, based on the arc-length method, provides more accurate results if it is able to converge on the solution. However, it experiences convergence problems depending upon the choice of mesh configuration and the selection of concrete post-cracking response parameters. The explicit dynamic solution procedure appears to be more robust than the arc-length method in the sense that it provides acceptable solutions in cases when the arc-length approach fails, however solution accuracy may be slightly lower and computational effort may be significantly larger. Furthermore, prestressing forces must be introduced into the finite element model in different ways for the explicit dynamic and arc-length solution procedures.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.1
• /
• pp.114-122
• /
• 2011

In this paper, we have identified the system instability factors in a bistatic radar system using pulse chasing and considered their effects on the bistatic receiver's MTI(Moving Target Indication) improvement performance. The pulse chasing is a method to efficiently scan a restricted search area within the limited transmitter power and time in a bistatic radar and to track a series of transmitted pulses using the receiver beam which has ideally matched to the pulse propagation rate. In this paper, we have discussed the interrelationship between the pulse chasing and time and frequency/phase synchronization and described the effects of the identified system instability factors on two kinds of MTI filter configuration, single delay-line and double delay-line, in the bistatic radar. And also, we have confirmed that the overall system improvement is restricted by a lower improvement factor among identified them, and discussed the allowable tolerance of the time and frequency/phase synchronization in the bistatic system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.130-131
• /
• 2008

Chalcogenide glass has been known for many photo induced phenomena and superial electron / optical specific by structure flexibility, unique electronic configuration. It is become known to the greatest specific as photonic material medium that possible to perfect controlling by continuity and photo inducing direction of amorphous chalcogenide. In our experiment, we choose the amorphous As-Ge-Se-S and coming glass as a substrate. And then we have evaporated in the ${\sim}2{\times}10^{-6}$ Torr using a E-beam evaporator, completed thin film sample that have 1um thickness of As-Ge-Se-S 600 $\AA$, 10~5 $\AA$/s. At first, we let the change the angle between laser and sample by holography litho method and then, expect that satisfied conclusion which 2-dimension diffraction lattice manufacture and specifics by investing a He-Ne laser for 2000 seconds.