• Smart Structures and Systems
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• v.25 no.3
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• pp.369-384
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• 2020

A wavefield sparse reconstruction technique based on compressed sensing is developed in this work to dramatically reduce the number of measurements. Firstly, a severely underdetermined representation of guided wavefield at a snapshot is established in the spatial domain. Secondly, an optimal compressed sensing model of guided wavefield sparse reconstruction is established based on l₁-norm penalty, where a suite of discrete cosine functions is selected as the dictionary to promote the sparsity. The regular, random and jittered undersampling schemes are compared and selected as the undersampling matrix of compressed sensing. Thirdly, a gradient projection method is employed to solve the compressed sensing model of wavefield sparse reconstruction from highly incomplete measurements. Finally, experiments with different excitation frequencies are conducted on an aluminum plate to verify the effectiveness of the proposed sparse reconstruction method, where a scanning laser Doppler vibrometer as the true benchmark is used to measure the original wavefield in a given inspection region. Experiments demonstrate that the missing wavefield data can be accurately reconstructed from less than 12% of the original measurements; The reconstruction accuracy of the jittered undersampling scheme is slightly higher than that of the random undersampling scheme in high probability, but the regular undersampling scheme fails to reconstruct the wavefield image; A quantified mapping relationship between the sparsity ratio and the recovery error over a special interval is established with respect to statistical modeling and analysis.

• Bulletin of the Korean Chemical Society
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• v.24 no.8
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• pp.1111-1118
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• 2003

We present one-color nonlinear wavepacket interferometry (WPI) signal calculations for a system of two electronic levels and one vibrational degree of freedom. We consider two cases, a displaced harmonic oscillator system, which can be treated analytically, and a model photodissociative system, whose WPI signal must be calculated by numerical wavepacket propagation. We show how signals obtained with different combinations of intrapulse-pair phase shifts can be combined to isolate the complex-valued overlap between a given onepulse target wavepacket and a variable three-pulse reference wavepacket. We demonstrate that with a range of inter- and intrapulse-pair delays the complex overlaps and variable reference states can be used to reconstruct the target wavepacket. We compare our results with previous methods for vibronic state reconstruction based on linear WPI and discuss further generalizations of our method.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.328-331
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• 2013

Incentive/Disincentive (I/D) contracting experiences in many states have been evaluated in terms of time and cost performance and substantial project time savings were found in many project cases. However, there is little understanding on individual project success factors for I/D projects during construction. This paper explores the significance of I/D clause in the success of the MacArthur Maze reconstruction project and summarizes a list of group causes that explains and elaborates on the detailed factors. The methods used for carrying out this study started with a search of online media and news reports and contract documents were also obtained from Caltrans. After review of the preliminary information, Interviews were performed with the Caltrans Resident Engineer and the contractor's project manager who were in charge of the MacArthur Maze reconstruction. In conclusion, the evaluation of their responses hinted at six significant cause groups responsible for the project's success. These groups can be listed as: 1) Motivation, 2) Policy, 3) Teamwork, 4) Communication, 5) Expectation, and 6) Resource Management.

• Journal of the Korean housing association
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• v.20 no.4
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• pp.49-57
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• 2009

Established redevelopment and reconstruction projects were unified into one law in 2003 when the 'Act of Urban, Residential and Environment Improvement' was enacted. However, the act only focused on the improvement of the physical state of residential environments established by maintenance projects. In order to be effective, the law also needs to improve the nonphysical aspects of the residential environment. While conducting our research and comparing it with past research, we identified the major factors of residential preferences in order to extract and analyze the nonphysical state of residential environments. As a result, we found that social and economic factors are significantly more important to residents than cultural factors. Also, we found that in each district studied the housing preferences were the most important in redevelopment and reconstruction with the exception of Sangdang-Gu (where the community was the most important factor) and Hungduk-Gu (where the social factor was most important). For future purposes, it is necessary to consider the variables according to each location in order to reflect the needs of the residents when building an apartment complex within the redevelopment and reconstruction district.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.340-340
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• 2010

Various structures of vacancy defects in graphene layers and carbon nanotubes have been reported by high resolution transmission electron microscope (HR-TEM) and those arouse an interest of reconstruction processes of vacancy defects. In this talk, we present reconstruction processes of vacancy defects in a graphene and a carbon nanotube by tight-binding molecular dynamics (TBMD) simulations and by first principles total energy calculations. We found that a structure of a dislocation defect with two pentagon-heptagon (5-7) pairs in graphene becomes more stable than other structures when the number of vacancy units is ten and over. The simulation study of scanning tunneling microscopy reveals that the pentagon-heptagon pair defects perturb the wavefunction of electrons near Fermi level to produce the $\sqrt{3}\;{\times}\;\sqrt{3}$ superlattice pattern, which is in excellent agreement with experiment. It is also observed in our tight-binding molecular dynamics simulation that 5-7 pair defects play a very important role in vacancy reconstruction in a graphene layer and carbon nanotubes.

• Phonetics and Speech Sciences
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• v.6 no.4
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• pp.127-132
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• 2014

This paper describes a robust speech recognition technique by reconstructing spectral components mismatched with a training environment. Although the cluster-based reconstruction method can compensate the unreliable components from reliable components in the same spectral vector by assuming an independent, identically distributed Gaussian-mixture process of training spectral vectors, the presented method exploits the temporal dependency of speech to reconstruct the components by introducing a hidden-Markov-model prior which incorporates an internal state transition plausible for an observed spectral vector sequence. The experimental results indicate that the described method can provide temporally consistent reconstruction and further improve recognition performance on average compared to the conventional method.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.151-151
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• 2000

We have studied the atomic structure of Si(100)-c(4$\times$4) reconstruction using scanning tunneling microscopy(STM). The c(4$\times$4) reconstruction can be formed by annealing the hydrogen exposured surface at temperatures between 850 and 960 K. At this temperature ranges, adsorbed hydrogen atoms are all desorbed. Therefore, the c(4$\times$4) reconstruction is due to the Si dimers on surface. The filled and empty state images of the STM were interpreted in terms of Si dimers in c(4$\times$4) primitive cell forming the reconstruction. Based on the STM images and hydrogen adsorption experiment on c(4$\times$40 surface, we suggest that Si dimers in c(4$\times$40 unit cell are perpendicular ad-dimer to the underlying Si dimer rows.

• Bulletin of the Korean Mathematical Society
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• v.50 no.1
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• pp.321-341
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• 2013

In this paper, we discuss the a posteriori error estimates of the semidiscrete mixed finite element methods for quadratic optimal control problems governed by linear hyperbolic equations. The state and the co-state are discretized by the order $k$ Raviart-Thomas mixed finite element spaces and the control is approximated by piecewise polynomials of order $k(k{\geq}0)$. Using mixed elliptic reconstruction method, a posterior $L^{\infty}(L^2)$-error estimates for both the state and the control approximation are derived. Such estimates, which are apparently not available in the literature, are an important step towards developing reliable adaptive mixed finite element approximation schemes for the control problem.

• Journal of Information Processing Systems
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• v.12 no.3
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• pp.338-357
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• 2016

The recent advent of increasingly affordable and powerful 3D scanning devices capable of capturing high resolution range data about real-world objects and environments has fueled research into effective 3D surface reconstruction techniques for rendering the raw point cloud data produced by many of these devices into a form that would make it usable in a variety of application domains. This paper, therefore, provides an overview of the existing literature on surface reconstruction from 3D point clouds. It explains some of the basic surface reconstruction concepts, describes the various factors used to evaluate surface reconstruction methods, highlights some commonly encountered issues in dealing with the raw 3D point cloud data and delineates the tradeoffs between data resolution/accuracy and processing speed. It also categorizes the various techniques for this task and briefly analyzes their empirical evaluation results demarcating their advantages and disadvantages. The paper concludes with a cross-comparison of methods which have been evaluated on the same benchmark data sets along with a discussion of the overall trends reported in the literature. The objective is to provide an overview of the state of the art on surface reconstruction from point cloud data in order to facilitate and inspire further research in this area.

• Journal of Korean Orthopaedic Sports Medicine
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• v.12 no.1
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• pp.1-7
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• 2013

This article provides an overview of the current concepts regarding anterior cruciate ligament reconstruction, including anatomy, biomechanics, operative techniques and clinical results. Many techniques have been introduced for ACL reconstruction: single bundle reconstruction, remnant preserving augmentation, and double bundle reconstruction. Each technique has its strong and weak points, and it is not sure which technique is superior than others. It is considered to suggest that rather than to select the same method of surgery in all patients, select the method of reconstruction depending on the characteristics of the individual patient, the state of the residual ligaments and extent of the damage.