• Journal of Information Processing Systems
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• v.12 no.2
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• pp.310-321
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• 2016

TCS_SHA-3 is a family of four cryptographic hash functions that are covered by a United States patent (US 2009/0262925). The digest sizes are 224, 256, 384 and 512 bits. The hash functions use bijective functions in place of the standard compression functions. In this paper we describe first and second preimage attacks on the full hash functions. The second preimage attack requires negligible time and the first preimage attack requires $O(2^{36})$ time. In addition to these attacks, we also present a negligible time second preimage attack on a strengthened variant of the TCS_SHA-3. All the attacks have negligible memory requirements. To the best of our knowledge, there is no prior cryptanalysis of any member of the TCS_SHA-3 family in the literature.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.233-236
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• 2003

A bumper comprises a bumper face, a bumper beam for distributing the load from the impacts applied to the bumper face and reinforcing the bumper, an absorber member interposed between the bumper face and the bumper beam, and a pair of bumper stays which secure the bumper beam to the vehicle body. A conventional bumper stay structure is assembled into several stamped parts, so several processes are needed and the structure is complicated. In this study the bumper stay is applied to the tubular hydroforming which is known to have several advantages such as the reduction of the number of the process and the part weight. The thickness distribution of the tube after hydroforming and the internal energy at the event of the a compression are mainly considered to evaluate the hydro-formability and energy absorption performance.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.15-19
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• 2000

Recently Western countries are now beginning to use ACM (Advanced Composites Material), in the construction industry Compared with existing construction materials, ACM possesses many advantages such as light-weight, high-strength, corrosion resistant property. Among other fabrication process of ACM, pultrusion is one of the promising one for civil infrastructure application. In this paper, the structural characteristics of pultruded GFRP strip and structural members of angle and tube type were studied. For the strip, parametric studies of pultrusion process has been carried out. Considered parameters were volume fraction, temperature, pulling speed and fiber orientations. For the pultruded angle and tube, compression test and buckling analysis has been carried out. The results were compared with calculated values using coded formulae

• Journal of the Society of Naval Architects of Korea
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• v.33 no.4
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• pp.106-123
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• 1996

This paper experimentally investigates the characteristics of Al-honeycomb sandwich panels which are considered as a promising primary strength member of weight critical large structures. Some tests on the aluminum honeycomb panels subject to 3-point bending or uniaxial compression or crushing load are carried out. Based on the test results, linear elastic response, buckling/ultimate strength and crushing/energy absorption capacity are discussed. Some guidelines for design of aluminum honeycomb panels are given.

• International Journal of Concrete Structures and Materials
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• v.11 no.1
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• pp.1-16
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• 2017

The compression or tension-controlled failure mode of concrete beams prestressed with unbonded FRP tendons is governed by the relative amount of prestressing tendon to the balanced one. Explicit assessment to determine the balanced reinforcement ratio of a beam with unbonded tendons (${\rho}^U_{pfb}$) is difficult because it requires a priori knowledge of the deformed beam geometry in order to evaluate the unbonded tendon strain. In this study, a theoretical evaluation of ${\rho}^U_{pfb}$ is presented based on a concept of three equivalent rectangular curvature blocks for simply supported concrete beams internally prestressed with unbonded carbon-fiber-reinforced polymer (CFRP) tendons. The equivalent curvature blocks were iteratively refined to closely simulate beam rotations at the supports, mid-span beam deflection, and member-dependent strain of the unbonded tendon at the ultimate state. The model was verified by comparing its predictions with the test results. Parametric studies were performed to examine the effects of various parameters on ${\rho}^U_{pfb}$.

• Journal of Korean Association for Spatial Structures
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• v.13 no.4
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• pp.67-74
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• 2013

The Age-adjusted effective Modulus Method(AEMM) is one of the methods adopted for the construction stage analysis of concrete structures. The AEMM uses the aging factor to consider the effects of the varying concrete stress. In the aspects of computation time and the accuracy of the results, the AEMM is considered as one of most appropriate methods for construction stage analysis of tall building structures. Previous researches proposed appropriate values of the aging factor in the forms of graphs or using very simple equations. In this paper, an equation for estimating the aging factor as a function of rebar ratio in the section, compressive strength of concrete, notional member dimension, and age of concrete at the load application. The validity of aging factor proposed in this paper were examined by the comparison with the results of step-by step method.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.10a
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• pp.209-216
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• 2000

The purpose of this study is to investigate elasto-plastic behaviour and estimate ultimate resistance capacity of the residential-commercial building subjected to lateral force along the height of structure. Four types of residential-commercial building are chosen as analytical models and investigated by pushover analysis. Pushover analysis estimates initial elastic stiffness, post-yielding stiffness, and plastic hinges on each story of structures through three-dimensional nonlinear analysis program CANNY-99. Skeleton curve of bending stiffness model is bilinear, shear stiffness model is trilinear, and axial stiffness model is elastic. Skeleton curve of axial stiffness model has the axial compression and tension stiffness of reinforced concrete members. This study presents the change of inter story drift, story stiffness and hinge of story and member.

• Journal of Industrial Technology
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• v.1
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• pp.9-16
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• 1981

In the steel Structural design, buckling is the main factor to determine size, particularly in compression member. Buckling may sometimes occur in the form of wrinkles in thin elements, such as webs, flanges, and other parts that make up a section. This phenomenon is called local buckling. The strength of the steel and the rigidity of the frame are considerably deteriorated by the local buckling. The specimens used for this experiments, H-Shape Steel beams composed by fillet-welding, are dessified classified into two groups, ie one for web test and another for flange fest. The aim of this study is to define the influences by the local bucking on the vesisting forces, deformation and the phenomena of the internal forces in the section, and to collect the basic data for design of steel beams.

• Journal of the Korea Institute of Building Construction
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• v.2 no.4
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• pp.99-104
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• 2002

Recently, the continuous fiber materials has become more important materials to repair and to reinforce concrete structural members. Continuous fiber meshes are effective for shear and confining reinforcement and provide excellent durability when combined with high strength mortar The purpose of this study is to verify the relationship between concrete strength and the ductility of inner concrete confined laterally by continuous fiber meshes. For this study, Experimental studies were conducted by compressive members using the cast frame of high strength mortar and continuous fiber meshes. Therefore, the result shows that compressive strength and ductility has improved according to the amount of the fiber meshes, and that the lateral confined effect of members with 3- or 4-axis mesh arrangement is bigger than that of members with 2-axis mesh. These data have to be used to verify the characteristic of concrete structure members reinforced continuous fiber mesh.

• Structural Engineering and Mechanics
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• v.51 no.5
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• pp.809-821
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• 2014

The truss based steel bridge structures usually consists of gusset plates which lose their load carrying capacity and rigidity under the effect of repeated and dynamics loads. This paper is focused on modeling the nonlinear material behavior of the gusset plates of the Truss Based Bridges subjected to dynamics loads. The nonlinear behavior of material is characterized by a damage coupled elsto-plastic material models. A truss bridge finite element model is established in Abaqus with the details of the gusset plates and their connections. The nonlinear finite element analyses are performed to calculate stress and strain states in the gusset plates under different loading conditions. The study indicates that damage initiation occurred in the plastic deformation localized region of the gusset plates where all, diagonal, horizontal and vertical, truss member met and are critical for shear type of failure due tension and compression interaction. These findings are agreed with the analytical and experimental results obtained for the stress distribution of this kind gusset plate.