• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.5 s.305
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• pp.19-26
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• 2005

In this paper, a new method for obtaining three-dimensional shape of an object by measuring relative blur between images using wavelet analysis has been described. Most of the previous methods use inverse filtering to determine the measure of defocus. These methods suffer from some fundamental problems like inaccuracies in finding the frequency domain representation, windowing effects, and border effects. Besides these deficiencies, a filter, such as Laplacian of Gaussian, that produces an aggregate estimate of defocus for an unknown texture, can not lead to accurate depth estimates because of the non-stationary nature of images. We propose a new depth from defocus (DFD) method using wavelet analysis that is capable of performing both the local analysis and the windowing technique with variable-sized regions for non-stationary images with complex textural properties. We show that normalized image ratio of wavelet power by Parseval's theorem is closely related to blur parameter and depth. Experimental results have been presented demonstrating that our DFD method is faster in speed and gives more precise shape estimates than previous DFD techniques for both synthetic and real scenes.

• Journal of Korea Water Resources Association
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• v.33 no.6
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• pp.815-825
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• 2000

In the present work Einstein's(l942) suspended load equation IS refined in vanous aspects. After checking the flow characteristics a new method is presented for the estimation of zero velocity point at the condition of smooth turbulent flow, and non-dimensional number of suspended load is introduced for the clear representation of suspended load equation. And a recent equation of bed load is employed in order to calculate accurately the sediment concentration at a reference point. Several approximation equations are also developed to compute directly or explicitly two integrals introduced in the equations. The refined equation has been tested against the measurement data collected by Brownlie(l981) in comparison with Einstein's original equation.uation.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.1
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• pp.38-48
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• 2007

In this paper, we propose an image-based method for modeling 3D objects with curved surfaces based on the NURBS (Non-Uniform Rational B-Splines) representation. Starting from a few calibrated images, the user specifies the corresponding curves by means of an interactive user interface. Then, the 3D curves are reconstructed using stereo reconstruction. In order to fit the curves easily using the interactive user interface, NURBS curves and surfaces are employed. The proposed surface modeling techniques include surface building methods such as bilinear surfaces, ruled surfaces, generalized cylinders, and surfaces of revolution. In addition to these methods, we also propose various advanced surface modeling techniques, including skinned surfaces, swept surfaces, and boundary patches. Based on these surface modeling techniques, it is possible to build various types of 3D shape models with textured curved surfaces without much effort. Also, it is possible to reconstruct more realistic surfaces by using proposed view-dependent texture acquisition algorithm. Constructed 3D shape model with curves and curved surfaces can be exported in VRML format, making it possible to be used in different 3D graphics softwares.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.963-971
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• 2008

Unsaturated soil mechanics has been often used to find out a cause of failure (tensile failure) of retaining walls and hill slopes containing sandy soils. Checking shear strength is a popular method by considering suction stress developed form pore water menisci among the grains and saturated pockets of pore water under negative pressure. Linear Mohr-Coulomb failure criterion is generally adopted as a failure criterion. However, depending on relative density, stress history, and the magnitude of stress, the failure behavior of sand may not follow linear M-C frictional behavior. For stress in the large compressive ranges, say from tens to hundreds of kPa, the linear M-C criterion is an adequate representation for the shear strength behavior of sand. However, less than tens of kPa, the M-C criterion often can not be accurately represented. Depending on failure criterion, the uniaxial tensile strength is different over 100% relative error. For sand behavior under small compression regimes, therefore, such as under low or zero gravity, or under undergoing tensile failure in the crest area of hill slopes or behind retaining walls, it is important to consider the non-linear behavior.

• Journal of IKEEE
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• v.19 no.3
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• pp.342-348
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• 2015

High speed implementation of digital filters is required in high data rate applications such as hard-wired wide band modem and high resolution video codec. Since the critical path of the digital filter is the MAC (multiplication and accumulation) circuit, the filter coefficient with sparse non-zero bits enables high speed implementation with adders of low hardware cost. Compressive sensing has been reported to be very successful in sparse representation and sparse signal recovery. In this paper a filter design method for digital FIR filters with CSD (canonic signed digit) coefficients using compressive sensing technique is proposed. The sparse non-zero signed bits are selected in the greedy fashion while pruning the mistakenly selected digits. A few design examples show that the proposed method can be utilized for designing sparse CSD coefficient digital FIR filters approximating the desired frequency response.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.5
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• pp.9-15
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• 2001

This paper describes measurement method of dielectric properties of dielectric materials using cylindrical cavity resonator's. Dielectric properties of concern here are relative permittivity, loss- tangent, quality factor and so on. An analysis of $TE_{011}$mode in dielectric properties of concentric dielectric-rod inserted cylindrical cavity resonator is presented. The frequency variation by the air gap at $TE_{011}$ mode turns out to be the least sensitive. A technique using a $TE_{011}$ mode of concentric dielectric-rod inserted cylindrical cavity resonator and an exact field representation of neo non-decaying mode are introduced for measurement of dielectric properties.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.1
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• pp.101-111
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• 1993

Many processes such as machining, injection-moulding and metal-forming are usually operated by hydraulic servo-systems. The dynamic characteristics of these systems are complex and highly non-linear and are often subjected to the uncertain external disturbances associated with the processes. Consequently, the conventional approach to the controller design for these systems may not guarantee accurate tracking control performance. An effective neuro-fuzzy controller is proposed to realize an accurate hydraulic servo-system regardless of the uncertainties and the external disturbances. For this purpose, first, we develop a simplified fuzzy logic controller which have multidimensional and unsymmetric membership functions. Secondly, we develop a neural network which consists of the parameters of the fuzzy logic controller. It is show that the neural network has both learning capability and linguistic representation capability. The proposed controller was implemented on a hydraulic servo-system. Feedback error learning architecture is adopted which uses the feedback error directly without passing through the dynamics or inverse transfer function of the hydraulic servo-system to train the neuro-fuzzy controller. A series of simulations was performed for the position-tracking control of the system subjected to external disturbances. The results of simulations show that regardless of inherent non-linearities and disturbances, an accuracy tracking-control performance is obtained using the proposed neuro-fuzzy controller.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.10
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• pp.5179-5196
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• 2019

To explore an effective non-invasion medical imaging diagnostics approach for hepatocellular carcinoma (HCC), we propose a method based on adopting the multiple technologies with the multi-parametric data fusion, transfer learning, and multi-scale deep feature extraction. Firstly, to make full use of complementary and enhancing the contribution of different modalities viz. multi-parametric MRI images in the lesion diagnosis, we propose a data-level fusion strategy. Secondly, based on the fusion data as the input, the multi-scale residual neural network with SPP (Spatial Pyramid Pooling) is utilized for the discriminative feature representation learning. Thirdly, to mitigate the impact of the lack of training samples, we do the pre-training of the proposed multi-scale residual neural network model on the natural image dataset and the fine-tuning with the chosen multi-parametric MRI images as complementary data. The comparative experiment results on the dataset from the clinical cases show that our proposed approach by employing the multiple strategies achieves the highest accuracy of 0.847±0.023 in the classification problem on the HCC differentiation. In the problem of discriminating the HCC lesion from the non-tumor area, we achieve a good performance with accuracy, sensitivity, specificity and AUC (area under the ROC curve) being 0.981±0.002, 0.981±0.002, 0.991±0.007 and 0.999±0.0008, respectively.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.2
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• pp.105-117
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• 2004

In each industry field, many engineers have tried to develop integrated environments using information technology. The core technology in building integrated environments is the database based on standardized information. To meet the requirements, this study builds a database with detailed design information as a part of integrating digital information generated from every work of steel bridges. The data model used to build the database was developed based on the international standard, namely ISO/STEP. The data model is classified into geometric and non-geometric parts to represent the design information of steel bridges. The geometric parts are represented by a three dimensional solid model so that they may be able to reuse existing information. Also, the non-geometric parts represent information requirements that are analyzed by the development method of standard data model. To verify the data model, this study validates the syntax of the model on EXPRESS Engine and verifies the validation of the model by applying the design data of Hannam bridge to the database.

• Journal of Digital Convergence
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• v.14 no.12
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• pp.495-501
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• 2016

The film has always reflected the culture of the era based on reality and imagination. The visual effect in the film has mainly played a role of expressing the reality more realistically or recognizing the virtual as reality. This study examines the meaning and the effect of fantasy realism through Oasis of Lee Chang-dong. Fantastic realism has separated the reality from the imaginary space by using a dual meaning tool that affects the time and space in the film and reflects the human desire and desire to see. It was also reproduced in the real world through the medium of pigeons. In addition, it separates visualized space from non-visualized space in film narrative structure, separation of real and unreal space, segregation of consciousness and unconscious space, and separation of reality and reality space into power structure. With the development of technology, the image of the yellow image comes closer to us like reality, which will express the space of unconsciousness that we could not think of.