• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.749-756
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• 2006

Because of the orthotropic elastic properties and significant two-way bending action, orthotropic plate theory may be suitable for describing the behavior of concrete filled grid bridge decks. Current AASHTO LRFD Bridge Design Specification(2004) has live load moment equations considering flexural rigidity ratio between longitudinal and transverse direction, but the Korea highway bridge design specification(2005) doesn't. The Korea highway bridge standard specification LRFD(1996) considers an orthotropic plate model with a single load to estimate live load moments in concrete filled grid bridge decks, which may not be conservative. This paper presents live load moment equations for truck and passenger car, based on orthotropic plate theory. The equations of truck model use multiple presence factor, impact factor, design truck and design tandem of the Korea highway bridge standard specification LRFD(1996). The estimated moments are verified through finite-element analyses.

• The korean journal of orthodontics
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• v.17 no.2
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• pp.185-200
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• 1987

This paper was undertaken to observe the displacement of craniofacial complex with cervical headgear and to compare narrowing or widening effect of palate by use of contraction or expansion face-bow, respectively. The 3-dimensional finite element method(FEM) was used for a mathematical model composed of 597 nodes and 790 elements and an electrical resistance strain gauge investigation was performed to validate the finite element model. The outer bow of cervical headgear was adjusted to be placed below the occlusal plane by $25^{\circ}$ and met the midsagittal plane by $40^{\circ}$, and was loaded 1kg on each right and left hook toward posterior direction. The results were as follows 1. Generally, the maxillary teeth and facial bone were displaced in posterior, medial and downward direction. 2. It was the maxillary 2nd bicuspid that moved bodily. 3. The craniofacial complex rotated in a clockwise direction around the rotating axis which lay from the most posterior and lowest point connecting nasal crest of maxillary bone and vomer, progressively toward a more posterior, lateral and upward direction, anterior and upper area of pterygomaxillary fissure, base of medial pterygoid plate and laterally to the contact area of zygomatic arch with squamous part of temporal bone. 4. No contraction effect was observed by contraction face-bow when compared to the standard face-bow. 5. In case of expansion face-bow, the areas of maxillary 2nd bicuspid, molars and palate were expanded remarkably.

• Structural Engineering and Mechanics
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• v.70 no.5
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• pp.513-524
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• 2019

This study proposed an improved particle swarm optimization (IPSO) method ensemble with kriging model for model updating. By introducing genetic algorithm (GA) and grouping strategy together with elite selection into standard particle optimization (PSO), the IPSO is obtained. Kriging metamodel serves for predicting the structural responses to avoid complex computation via finite element model. The combination of IPSO and kriging model shall provide more accurate searching results and obtain global optimal solution for model updating compared with the PSO, Simulate Annealing PSO (SimuAPSO), BreedPSO and PSOGA. A plane truss structure and ASCE Benchmark frame structure are adopted to verify the proposed approach. The results indicated that the hybrid of kriging model and IPSO could serve for model updating effectively and efficiently. The updating results further illustrated that IPSO can provide superior convergent solutions compared with PSO, SimuAPSO, BreedPSO and PSOGA.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.694-697
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• 2007

In this paper, a nonlinear finite element analysis program NUCAS, which has been developed for assessment of pressure capacity and failure mode for nuclear containment building is described. Degenerated shell element with assumed strain method and low-order solid element with enhanced assumed strain method is adapted to microscopic material and elasto-plastic material model, respectively. Finally, the performance of the developed program is tested and demonstrated with several examples. From the numerical tests, the present results show a good agreement with experimental data or other numerical results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.70-73
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• 2009

The aim of this research is to obtain a numerical material model for an amorphous glassy polymer, polycarbonate (PC), which can be used in finite element analysis (FEA) of the micro thermal imprint process near the glass transition temperature. An understanding of the deformation behavior of the PC specimens was acquired by performing tensile stress relaxation tests. The viscoelastic material model based on generalized Maxwell model was introduced for the material near Tg to establish the FE model based on the commercial FEA code ABAQUS/Standard with a suitable set of parameters obtained for this material model from the test data. Further validation of the model and parameters was performed by comparing the analysis of FE model results to the experimental data.

• Journal of Navigation and Port Research
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• v.36 no.9
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• pp.707-714
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• 2012

Recently, tug boats are widely used for towing a barge which transports building materials, a large block of a ship, offshore crane, and so on. In order to simulate the dynamics of the coupled towing system correctly, the dynamics of the towline should be well modeled. In this paper, the towline was modeled as the multiple finite elements, and each element was assumed as a rigid cylinder which moves in five degrees of freedom except roll. The external tension and its moment acting on each element of the towline were modeled depending on the position vector's direction. Tugboat's motion was simulated in six degrees of freedom where wave and current effects were included, and towed barge was assumed to move in the horizontal plane only. In order to confirm the mathematical models of the coupled towing systems, standard maneuvering trials such as course changing maneuver, turning circle test and zig-zag test were simulated. In addition, the same trials were simulated when the external disturbances like wave and current exist. As the result, it is supposed that the results might be qualitatively reasonable.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.231-237
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• 2006

Recently railroad industry pulls a new interest with stability, fixed time characteristic, low environment pollution characteristic and mass transportation characteristic. With industrial development railroad it joins in, The many research and regulation production are coming to do. Specially like this activities are coming to be advanced actively from North America and Europe. From viewpoint of railway car production company, The vehicle production that a suitable Europe standard is essentiality for find a Europe market that The whole vehicle consuming hold it does a most big specific gravity. From this study, developed finite element model for analysis technology about crashworthiness of inside GM/RT 2100 standard and analyzed crash results.

• Transactions of Materials Processing
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• v.22 no.6
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• pp.303-309
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• 2013

Spring-back of MS1470 steel sheets was numerically predicted using a non-linear kinematic hardening material behavior based on the Yoshida-Uemori model. From uniaxial tension and uniaxial tension-compression-tension data as well as the uniaxial tension-unloading-tension data, the parameters of the Yoshida-Uemori model were obtained. For the numerical simulations, the Yoshida-Uemori model was implemented into the commercial finite element program, ABAQUS/Explicit and ABAQUS/Standard using the user-defined material subroutines. The model performance was validated against the measured spring-back from the benchmark problems of NUMISHEET 2008 and NUMISHEET 2011, the 2-D draw bending test and the S-rail forming test, respectively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.3
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• pp.163-171
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• 1992

The narrow interal grid is effective in accuracy, but it is not able to make a densely grided sample, so that smoothing is requared. In digital elevation models, an application of the finite elements method is effective to smooth the undesired noise which is generated in aquisition of elevation data. And this is one of the simple and direct method to solve the problem for discontinuity of terrain. Therefore, the finite elements method is applied to study. In digital elevation model by appling the finite element, smoothing is affected by the height weight. In this study, the relation equation between elevation weight and standard deviation of smoothing was obstained as Y = 1900625 $X^4-312987.6$ $X^3+20330.72$ $X^2-578.6029$ X+12.63772 and from this function, Optimum elevation weight is 0.05.

• Computers and Concrete
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• v.7 no.4
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• pp.365-386
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• 2010

This paper presents the physical formulation of a 1D material model suitable for seismic applications. It is written within the framework of thermodynamics with internal variables that is, especially, very efficient for the phenomenological representation of material behaviors at macroscale: those of the representative elementary volume. The model can reproduce the main characteristics observed for concrete, that is nonsymetric loading rate-dependent (viscoelasticity) behavior with appearance of permanent deformations and local hysteresis (continuum plasticity), stiffness degradation (continuum damage), cracking due to displacement localization (discrete plasticity or damage). The parameters have a clear physical meaning and can thus be easily identified. Although this point is not detailed in the paper, this material model is developed to be implemented in a finite element computer program. Therefore, for the benefit of the robustness of the numerical implementation, (i) linear state equations (no local iteration required) are defined whenever possible and (ii) the conditions in which the presented model can enter the generalized standard materials class - whose elements benefit from good global and local stability properties - are clearly established. To illustrate the capabilities of this model - among them for Earthquake Engineering applications - results of some numerical applications are presented.