• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.4
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• pp.437-448
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• 2000

In this study, a numerical analysis method for soil-pile interaction in frequency domain problem is presented. The total soil-pile interaction system is divided into two parts so called near field and far field. In the near field, beam elements are used lot a pile and plain strain finite elements for soil. In the far field, dynamic fundamental solution for multi-layered half planes based on boundary element formulation is adopted lot soil. These two fields are coupled using FE-BE coupling technique. In order to verify the proposed soil-pile interaction analysis, the dynamic responses of pile on multi-layered half planes are simulated and the results are compared with the experimental results. Also, various numerical analyses of piles considering different conditions of soil-pile interaction system are performed to examine the dynamic behavior of the system. It has been found that the developed method which satisfies the radiation conditions of multi-layered half planes can be applied to various structure systems effectively in frequency domain.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.191-198
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• 2011

In this paper, a method to approximate a multi-layer Green's function is proposed based on a FDTD scheme and a rational function approximation. For a given horizontal propagation wavenumber, time domain response is calculated and then Fourier transformed to the spectral domain Green's function. Using the rational function approximation, the pole and residue of the Green's function can be estimated, which are crucial for a calculation of a path loss. The proposed method can provide a wideband Green's function, while the conventional normal mode method can be applied to a single frequency problem. To validate the proposed method, We consider two problems, one of which has a analytical solution. The other is about multi-layer case, for which the proposed method is compared with the known normal mode solution, Kraken.

• International Journal of CAD/CAM
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• v.5 no.1
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• pp.99-109
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• 2005

This paper introduces an approach to an ontology-based multi-level knowledge framework for a knowledge management system for discrete-product development. Participants in a product life cycle want to share comprehensive product knowledge without any ambiguity and heterogeneity. However, previous knowledge management approaches are limited in providing those aspects: therefore, we suggest an ontology-based multi-level knowledge framework (OBMKF). The bottom level, the axiom, specifies the semantics of concepts and relations of knowledge so ambiguity can be alleviated. The middle level is a product development knowledge map; it defines the concepts and the relations of the product domain knowledge and guides the engineer to process their engineering decisions. The middle level is then classified further into more detailed levels, such as generic product level, specific product level, product version level, and manufactured item level, according to the various viewpoints. The top level is specialized knowledge for a specific domain that gives the solution of a specific task or problem. It is classified into three knowledge types: expert knowledge, engineering function knowledge, and data-analysis-based knowledge. This proposed framework is based on ontology to accommodate a comprehensive range of knowledge and is represented with first-order logic to maintain a uniform representation.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.595-598
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• 2002

This paper proposes neighborhood reduction techniques in local search of the customer decomposition subproblem in the Multi Depots Vehicle Routing Problem with Time Windows (MDVRPTW) by using geospatial relation among depots and customers. The neighborhood of the customer decomposition subproblem can be simply and well defined but it should include excessively bad solution candidates. Our techniques find such candidates by using information of the problem domain, geographical relation. We use our techniques in Tabu Search and evaluate the effectiveness in computer experiment.

• Structural Engineering and Mechanics
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• v.33 no.3
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• pp.285-306
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• 2009

In the literature the problem of the topology optimization of the structure is usually solved for one, clearly described from the mechanical point of view material. Generally the topology optimization answers the question of the distribution of this mentioned above material within the design domain. Finally, material-voids distribution it is obtained. In this paper, for the structure mainly strengthened or sometimes weakened by the inclusions, the variation approach of the topology optimization problem is formulated. This multi material approach may be useful for the design process of various mechanical or civil engineering structures which need to be more "refined" and more "optimal" than they can be using previous topology optimization procedures of optimization one material structures.

• Earthquakes and Structures
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• v.5 no.3
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• pp.359-378
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• 2013

The problem of identification of multi-component and (or) spatially varying earthquake support motions based on measured responses in instrumented structures is considered. The governing equations of motion are cast in the state space form and a time domain solution to the input identification problem is developed based on the Kalman and particle filtering methods. The method allows for noise in measured responses, imperfections in mathematical model for the structure, and possible nonlinear behavior of the structure. The unknown support motions are treated as hypothetical additional system states and a prior model for these motions are taken to be given in terms of white noise processes. For linear systems, the solution is developed within the Kalman filtering framework while, for nonlinear systems, the Monte Carlo simulation based particle filtering tools are employed. In the latter case, the question of controlling sampling variance based on the idea of Rao-Blackwellization is also explored. Illustrative examples include identification of multi-component and spatially varying support motions in linear/nonlinear structures.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.11
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• pp.3658-3679
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• 2022

Classification of persons wearing and not wearing face masks in images has emerged as a new computer vision problem during the COVID-19 pandemic. In order to address this problem and scale up the research in this domain, in this paper a hybrid technique by employing ResNet-101 and multi-layer perceptron (MLP) classifier has been proposed. The proposed technique is tested and validated on a self-created face masks classification dataset and a standard dataset. On self-created dataset, the proposed technique achieved a classification accuracy of 97.3%. To embrace the proposed technique, six other state-of-the-art CNN feature extractors with six other classical machine learning classifiers have been tested and compared with the proposed technique. The proposed technique achieved better classification accuracy and 1-6% higher precision, recall, and F1 score as compared to other tested deep feature extractors and machine learning classifiers.

• Structural Engineering and Mechanics
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• v.10 no.4
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• pp.359-369
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• 2000

Random loading identification has long been a difficult problem for Multi-Input-Multi-Output (MIMO) structure. In this paper, the Pseudo Excitation Method (PEM), which is an exact and efficient method for computing the structural random response, is extended inversely to identify the excitation power spectral densities (PSD). This identified method, named the Inverse Pseudo Excitation Method (IPEM), resembles the general dynamic loading identification in the frequency domain, and can be used to identify the definite or random excitations of complex structures in a similar way. Numerical simulations are used to reveal the the difficulties in such problems, and the results of some numerical analysis are discussed, which may be very useful in the setting up and processing of experimental data so as to obtain reasonable predictions of the input loading from the selected structural responses.

• Journal of Korean Institute of Industrial Engineers
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• v.24 no.4
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• pp.539-550
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• 1998

A computerized layout system based on a constraint satisfaction problem (CSP) technique was developed to treat both facility layout and instrument panel layout problems. This layout system attempts to allocate various facilities under multiple layout criteria including qualitative design objectives. Since most of the design objectives can be understood as constraints which the layout solution must satisfy to improve the goodness of the solution, a CSP technique was employed to solve the multi-constraints layout problem. The effectiveness of the system was evaluated by the comparison with the well-known facility layout program, CORELAP. Furthermore, the proposed system can also be applied to the instrument panel layout problem successfully. Several user-centered guidelines were well reflected on the solution obtained. CONSLAY, the prototype layout system being developed in the research, greatly enhanced the interactions with the designer so as to deal with the problem-dependent nature of the layout problem and to properly reflect the domain-specific knowledge of the designer.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.1
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• pp.99-108
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• 2010

RFID(Radio Frequency IDentification) is a technology that automatically identifies objects containing the electronic tags by using radio wave. When there are some tags in the domain of the RFID reader, the mechanism that can solve a collision between the tags occurs is necessary. The multi tag identification problem is the core issue in the RFID and could be resolved by the anti-collision algorithm. However, RFID system has another problem. The problem id user information security. Tag response easily by query of reader, so the system happened user privacy violent problem by tag information exposure. In the case, RFID system id weak from sniffing by outside. In this paper, We study of security robustness for tree-walking algorithm, query tree algorithm and advanced query tree algorithm of tree based memoryless algorithm.