• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.306-309
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• 2006

The fully embedded composite truss beam is developed based on composite member, truss system before composite and beam system after composite. The proper design concept and method of the fully embedded composite truss beam are discussed. A bending test on the fully embedded composite truss beam with span length 25.0m is carried out to investigate the flexural behavior and ultimate strength of the developed structure up to failure. A good agreement between the measured and predicted results are observed.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.6
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• pp.861-868
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• 2023

One of the key technologies in providing data analysis in the deep learning while maintaining security is fully homomorphic encryption. Due to constraints in operations on fully homomorphically encrypted data, non-arithmetic functions used in deep learning must be approximated by polynomials. Until now, the degrees of approximation polynomials with composite minimax polynomials have been uniformly set across layers, which poses challenges for effective network designs on fully homomorphic encryption. This study theoretically proves that setting different degrees of approximation polynomials constructed by composite minimax polynomial in each layer does not pose any issues in the inference on convolutional neural networks.

• Journal of Korean Society of Steel Construction
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• v.16 no.3 s.70
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• pp.325-332
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• 2004

Cross sections of steel-plate girder bridges are divided into three cross sections of non-composite, partially composite, and fully composite sections, according to their composite characteristics. The Korean provision for the partially and fully composite sections specifies general usage of the stud of shear connectors, whereas the one for the non-composite section specifies empirical usage of slab anchors. However, the actual behavior of the cross sections of steel-plate girder bridges using slab anchors is close not to the non-composite action, but to the partially composite action. Therefore analytical and experimental studies on partial composites of steel-plate girder bridges using slab anchors are performed in this study. Intial stiffness of the slab anchor is obtained by the experimental study for the first time, and the composite characteristic of simple-span and two-span continuous steel-plate girder bridges is investigated by the finite element analyses for the second time. Based on the obtained initial stiffness, the reduction effect of tensile stresses in the concrete-slab on the intermediate support of the continuous bridge is also considered herein.

• Advances in concrete construction
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• v.15 no.6
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• pp.391-404
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• 2023

In this study, the modeling of the transverse connection of fully precast steel-UHPC (Ultra-High-Performance Concrete) lightweight composite bridges were conducted. The transverse connection between precast components plays a critical role in the overall performance and safety of the bridge. To achieve an accurate and reliable simulation of the interface behavior, the cohesive model in ABAQUS was employed, considering both bending-tension and compression-shear behaviors. The parameters of the cohesive model are obtained through interface bending and oblique shear tests on UHPC samples with different surface roughness. By validating the numerical simulation against actual joint tests, the effectiveness and accuracy of the proposed model in capturing the interface behavior of the fully precast steel-UHPC lightweight composite bridge were demonstrated.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.29-32
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• 2005

Based on the full layerwise displacement shell theory, vibration and damping characteristics of cylindrical sandwich panels are investigated. The transverse shear deformation and the normal strain are fully taken into account for structural damping modelling. Modal damping factors and frequency response functions are analyzed for various structural parameters of cylindrical sandwich beams. Present results shows that full layerwise theory can accurately predict vibration and damping characteristics of cylindrical composite panels with surface damping treatments and constrained layer damping. The viscoelastic materials depending on elevated temperature environment and exciting frequencies can be fully considered.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.146-149
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• 2003

Two-way shape memory effect(TWSME) under residual stresses are considered in the present study. The structure using two-way shape memory alloy(SMA) concept returns to its initial shape by increasing or decreasing temperature under the initially given residual stress. In the present study, we use a thermo-mechanical constitutive equation of SMA and laminated composite plates are considered as simple morphing structural components which are based on first order shear deformable laminated composite plate with large deflection. Numerical results of fully coupled SMA-composite structures are presented

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.123-126
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• 2004

Two-way shape memory effect(TWSME) under residual stresses are considered in the present study. The structure using two-way shape memory effect concept returns to its initial shape by increasing or decreasing temperature under the initially given residual stress. In the present study, we use a thermo-mechanical constitutive equation of SMA and laminated composite beam are considered as simple morphing structural components which are based on large deformable 2D composite beam theory. Numerical results of fully coupled SMA-composite structures are presented.

• Structural Engineering and Mechanics
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• v.4 no.2
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• pp.111-124
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• 1996

New active "intelligent" structural systems with integrated self-sensing, diagnosis, and control capabilities can lead to a new design dimension for the next generation high-performance structures and mechanical systems. However, temperature effects to the piezoelectric transducers are not fully understood. This paper is concerned with a mathematical modeling and analysis of a laminated piezothermoelastic cylindrical shell composite exposed to mechanical, electric, and thermal fields. Generic shell equations and solution procedures are derived. Contributions of spatial and time components in the mechanical, electric, and temperature excitations are discussed, and their analytical solutions derived. A laminated cylindrical shell composite with fully distributed piezoelectric layers is used in a case study; its multi-field step and impulse responses are investigated. Analyses suggest that the fully distributed actuators are insensitive to even modes due to load averaging and cancellation. Accordingly, these even modes are filtered from the total response and only the modes that are combinations of m = 1, 3, 5, ${\cdots}$ and n = 1, 3, 5, ${\cdots}$ participating in dynamic response of the shell.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.2
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• pp.424-427
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• 2007

A fully differential transconductor using the series composite transistor is proposed. Simulation results show that THD is less than 1.2% for the differential input signal of up to $1.5V_{p-p}$ when the input signal frequency is 10MHz. i he proposed transconductor is used to design a third-order elliptic Gm-C lowpass filter with 138kHz cutoff frequency for ADSL Tx filter. The design procedure is based on signal flow graph(SFG) of a doubly-terminated LC ladder filter by means of fully differential transconductors and capacitors. The filter is fabricated and measured with a $0.35{\mu}m$ CMOS process.

• Advanced Composite Materials
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• v.16 no.4
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• pp.283-298
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• 2007

Environment-friendly composites reinforced with bagasse fiber (BF), a kind of natural fiber as the remains from squeezed sugarcane, were fabricated by injection molding and press molding. As appropriate matrices for injection molding and press molding, polypropylene (PP) and polycaprolactone-cornstarch (PCL-C) were selected, as a typical recyclable resin and biodegradable resin, respectively. The mechanical properties of BF/PP composites were investigated in view of fiber mass fraction and injection molding conditions. And the mechanical properties and the biodegradation of BF/PCL composites were also evaluated. In the case of injection molding, the flexural modulus increased with an increase in fiber mass fraction, and the mechanical properties decreased with an increase in cylinder temperature due to the thermal degradation of BF. The optimum conditions increasing the flexural properties and the impact strength were $90^{\circ}C$ mold temperature, 30 s injection interval, and in the range of 165 to $185^{\circ}C$ cylinder temperature. On the other hand, as to BF/PCL-C fully-green composites, both the flexural properties and the impact strength increased with an increase in fiber mass fraction. It is considered that the BF compressed during preparation could result in the enhancement in mechanical properties. The results of the biodegradability test showed the addition of BF caused the acceleration of weight loss, which increased further with increasing fiber content. This reveals that the addition and the quantities of BF could promote the biodegradation of fully-green composites.