• Computers and Concrete
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• v.19 no.4
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• pp.375-385
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• 2017

In the present paper experimental and numerical analysis of hook-ended steel fiber reinforced concrete is carried out. The experimental tests are performed on notched beams loaded in 3-point bending using fiber volume fractions up to 1.5%. The numerical analysis of fiber reinforced concrete beams is performed at meso scale. The concrete is discretized with 3D solid finite elements and microplane model is used as a constitutive law. The fibers are modelled by randomly generated 1D truss finite elements, which are connected with concrete matrix by discrete bond-slip relationship. It is demonstrated that the presented approach, which is based on the modelling of concrete matrix using microplane model, able to realistically replicate experimental results. In all investigated cases failure is due to the pull-out of fibers. It is shown that with increase of volume content of fibers the effective bond strength and slip capacity of fibers decreases.

• Journal of Power Electronics
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• v.12 no.2
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• pp.368-376
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• 2012

This paper deals with an optimization approach of 3D space placement of power components under volume and thermal constraints. It consists in optimizing semiconductors positions on a heat sink by respecting the components junction temperatures and minimizing the heat sink size. The aim is to remove risks on the 3D converter components placement and ensure their effective integration before carrying out the first physical prototype. This approach is based on coupling an optimization environment with a thermal finite element simulation tool. A pre-sizing step using analytical models is performed to set the optimization computations coupled to numerical simulation.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.519-521
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• 2003

Within the paper an approach for the automatic extraction and reconstruction of buildings in urban built-up areas base on fusion of high-resolution satellite image and LIDAR data is presented. The presented data fusion scheme is essentially motivated by the fact that image and range data are quite complementary. Raised urban objects are first segmented from the terrain surface in the LIDAR data by making use of the spectral signature derived from satellite image, afterwards building potential regions are initially detected in a hierarchical scheme. A novel 3D building reconstruction model is also presented based on the assumption that most buildings can be approximately decomposed into polyhedral patches. With the constraints of presented building model, 3D edges are used to generate the hypothesis and follow the verification processes and a subsequent logical processing of the primitive geometric patches leads to 3D reconstruction of buildings with good details of shape. The approach is applied on the test sites and shows a good performance, an evaluation is described as well in the paper.

• Bulletin of the Korean Chemical Society
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• v.21 no.11
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• pp.1095-1100
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• 2000

we have proposed a three-dimensional GLE approach to gas-surface reactive scattering, model H + H $${\rightarrow}$H_2/Si(100)-(2$ ${\times}$1) system, and the implementation of 3D GLE method on the hydrogen on silicon surface has been presented. The formalism and algori thm of the 3D GLE are worked properly in the reactive scattering system. The calculated normal mode frequencies of surface vibrations were almost identical to previous harmonic slab calculations. The reaction probabilities were calculated for two energies. The calculations show that a very large amount of energy is transferred in surface in low energy scattering. Three different types of reaction mechanisms has been observed, which can not be shown in flat and rigid surface models. Further work on the reaction mechanisms and calculations of the vibrational and rotation distributions of products is in progress. The results will be reported elsewhere soon.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.223-229
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• 2020

The present work proposes a solution to the static Boltzmann transport equation approximated by the simplified P₃ (SP₃) on angular, and the analytic coarse mesh finite difference (ACMFD) for spatial variables. Multi-group SP₃-ACMFD equations in 3D rectangular geometry are solved using the GMRES solution technique. As the core time dependent analysis necessitates the solution of an eigenvalue problem for an initial condition, this work is hence devoted to development and verification of the proposed static SP₃-ACMFD solver. A 3D multi-group static diffusion solver is also developed as a byproduct of this work to assess the improvement achieved using the SP₃ technique. Static results are then compared against transport benchmarks to assess the proximity of SP₃-ACMFD solutions to their full transport peers. Results prove that the approach can be considered as an acceptable interim approximation with outputs superior to the diffusion method, close to the transport results, and with the computational costs less than the full transport approach. The work would be further generalized to time dependent solutions in Part II.

• Journal of the Korea Society of Computer and Information
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• v.11 no.3
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• pp.41-47
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• 2006

The range-based method is easy to get the 3D data in detail, but the image-based is not. In this paper. employing the magnifying lens. the new approach to get the 3D data in detail is suggested. The magnifying lens amplifies the disparity in stereo vision system and the amplification of disparity is to increase the resolution of the depth. We mathematically and experimentally verifies the fact to amplify the disparity and suggests the method to improve the original 3D data with the detail 3D data.

• Journal of the Korea Society of Computer and Information
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• v.23 no.3
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• pp.25-31
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• 2018

In this paper, we consider the game theoretic approach to investigate the transmit power optimization problem where D2D users share the uplink of the cellular system. Especially, we formulate the transmit power optimization problem as a non cooperative power control game. In the user wide sense, each user may try to select its transmit power level so as to maximize its utility in a selfish way. In the system wide, the transmit power levels of all users eventually converge to the unique point, called Nash Equilibrium. We first formulate the transmit power optimization problem as a non cooperative power control game. Next, we examine the existence of Nash Equilibrium. Finally, we present the numerical example that shows the convergence to the unique transmit power level.

• ETRI Journal
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• v.45 no.6
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• pp.1035-1045
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• 2023

We propose a novel graphics processing unit (GPU) algorithm that can handle a large-scale 3D fast Fourier transform (i.e., 3D-FFT) problem whose data size is larger than the GPU's memory. A 1D FFT-based 3D-FFT computational approach is used to solve the limited device memory issue. Moreover, to reduce the communication overhead between the CPU and GPU, we propose a 3D data-transposition method that converts the target 1D vector into a contiguous memory layout and improves data transfer efficiency. The transposed data are communicated between the host and device memories efficiently through the pinned buffer and multiple streams. We apply our method to various large-scale benchmarks and compare its performance with the state-of-the-art multicore CPU FFT library (i.e., fastest Fourier transform in the West [FFTW]) and a prior GPU-based 3D-FFT algorithm. Our method achieves a higher performance (up to 2.89 times) than FFTW; it yields more performance gaps as the data size increases. The performance of the prior GPU algorithm decreases considerably in massive-scale problems, whereas our method's performance is stable.

• Korean Journal of Computational Design and Engineering
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• v.11 no.6
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• pp.393-402
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• 2006

The purpose of this study is to develop mechanisms of nD model-based design by the combination of 2D drawing standards and 3D building models from the current 2D and text-based design. The aim of this study can be archived by defining the 2D model extension definitions for the IFC model development and harmonizing existing 2D standards. The paper examines 1) 3D Representation of Building Element and Building Services element, and 2D Model extension of IFC2X.2, 2) Basic development of additional 2D element that should be added to IFC model, and 3) mapping method between current 2D standard and IFC2.X2. Following this approach, the interoperability problem between 3D model and 2D drawing can be solved and finally an extended data model could be developed.

• Structural Monitoring and Maintenance
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• v.9 no.3
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• pp.237-258
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• 2022

This paper studies detecting and locating loose bolts using nonlinear guided waves. The 3D Finite Element (FE) simulation is used for the prediction of guided waves' interactions with loose bolted joints. The numerical results are verified by experimentally obtained data. The study considers bolted joints consisting of two bolts. It is shown that the guided waves' interaction with surfaces of a loose bolted joint generates Contact Acoustic Nonlinearity (CAN). The study uses CAN for detecting and locating loose bolts. The processed experimentally obtained data show that the CAN is able to successfully detect and locate loose bolted joints. A 3D FE simulation scheme is developed and validated by experimentally obtained data. It is shown that FE can predict the propagation of guided waves in loose bolts and is also able to detect and locate them. Several numerical case studies with various bolt sizes are created and studied using the validated 3D FE simulation approach. It is shown that the FE simulation modeling approach and the signal processing scheme used in the current study are able to detect and locate the loose bolts in imperfect bolted joints. The outcomes of this research can provide better insights into understanding the interaction of guided waves with loose bolts. The results can also enhance the maintenance and repair of imperfect joints using the nonlinear guided waves technique.