• Journal of Biomedical Engineering Research
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• v.24 no.5
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• pp.473-480
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• 2003

Iterative reconstruction methods have played a prominent role in emission computed tomography due to their remarkable advantages over the conventional filtered backprojection method. However, since iterative reconstructions typically are comprised of repeatedly projecting and backprojecting the data, the computational load required for reconstructing an image depends highly on the performance of the projector-backprojector pair used in the algorithm. In this work we compare quantitative performance of representative methods for implementing projector-backprojector pairs. To reduce the overall cost for the projection-backprojection operations for each method, we investigate how previously computed results can be reused so that the number of redundant calculations can be minimized. Our experimental results demonstrate that the ray tracing method not only outperforms other methods in computation time, but also provides improved reconstructions with good accuracy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2C
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• pp.213-221
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• 2004

A new method for design of two-channel finite-impulse response(FIR) quadrature mirror-image filter(QMF) banks with low reconstruction delay using weighting function is proposed. The weighting function used in this paper is calculated from the previous updated filter coefficients vector which is adjusted from iteration to iteration in the design of QMF banks. In this paper, passband and stopband edge frequency are used in design of QMF banks with low delay characteristic in time domain instead of specific frequency interval where the artifacts occur in conventional design method. The investigation of specific frequency interval where artifacts occur can not be required by using passband and stopband edge frequency. Some comparisons of performance are made with other existing design method to demonstrate the proposed method for QMF bank design. and it was observed that the proposed method using the weighted function and passband and stopband edge frequency improves the peak reconstruction error by 0.001 [dB], the peak-to-peak passband ripple by 0.003[dB], SNR with a white noise by 7[dB] and SNR with a step input by 32[dB], but with a reduction of the computational efficiency because of updating the weighting function over the conventional method in Ref [11].

• Journal of the Korea Computer Graphics Society
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• v.22 no.5
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• pp.1-16
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• 2016

In this paper, we propose and efficient curve reconstruction method based on the classical least-square fitting scheme. Specifically, given planar sample points equipped with normals, we reconstruct the objective curve as the zero set of a hierarchical implicit ZP(Zwart-Powell)-spline that can recover large holes of dataset without loosing the fine details. As regularizers, we adopted two: a Tikhonov regularizer to reduce the singularity of the linear system and a discrete Laplacian operator to smooth out the isocurves. Benchmark tests with quantitative measurements are done and our method shows much better quality than polynomial methods. Compared with the hierarchical bi-quadratic spline for datasets with holes, our method results in compatible quality but with less than 90% computational overhead.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1023-1030
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• 2020

We address the sampling set selection problem for arbitrary graph signals such that the original graph signal is reconstructed from the signal values on the nodes in the sampling set. We introduce a variation difference as a new indirect metric that measures the error of signal variations caused by sampling process without resorting to the eigen-decomposition which requires a huge computational cost. Instead of directly minimizing the reconstruction error, we propose a simple and fast greedy selection algorithm that minimizes the variation differences at each iteration and justify the proposed reasoning by showing that the principle used in the proposed process is similar to that in the previous novel technique. We run experiments to show that the proposed method yields a competitive reconstruction performance with a substantially reduced complexity for various graphs as compared with the previous selection methods.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.10
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• pp.150-161
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• 2013

This paper presents a new system which produces high resolution 3D contents by capturing multiview images of an object using multiple cameras, and estimating geometric and texture information of the object from the captured images. Even though a variety of multiview image-based 3D reconstruction systems have been proposed, it was difficult to generate high resolution 3D contents because multiview image-based 3D reconstruction requires a large amount of memory and computation. In order to reduce computational complexity and memory size for 3D reconstruction, the proposed system predetermines the regions in input images where an object can exist to extract object boundaries fast. And for fast computation of a visual hull, the system represents silhouettes and 3D-2D projection/back-projection relations by chain codes and 1D homographies, respectively. The geometric data of the reconstructed object is compactly represented by a 3D segment-based data format which is called DoCube, and the 3D object is finally reconstructed after 3D mesh generation and texture mapping are performed. Experimental results show that the proposed system produces 3D object contents of $800{\times}800{\times}800$ resolution with a rate of 2.2 seconds per frame.

• The Journal of Korean Association of Computer Education
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• v.21 no.5
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• pp.1-10
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• 2018

The revised informatics is to be compulsory for middle school students from 2018 according to 2015 revised curriculum. The concept of abstraction in informatics curriculum has common features and differences compared with general abstraction, however there is a mix of concepts in the current informatics textbook. The abstraction of computational thinking needs to connect with automation, so it is difficult to teach correct concept of abstraction with these textbooks. Therefore, this research conducted to investigate several informatics textbooks that were developed by the revised curriculum and to analyze the concept and examples of abstraction. As a result, some textbooks have that there is a mix of concepts about general abstraction and no connection with automation. This research suggests clarified abstraction and educational examples for cultivating computational thinking to improve this situation. This result will be basic recourse for the reconstruction of abstraction lesson to improving computational thinking.

• Journal of Microbiology and Biotechnology
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• v.32 no.3
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• pp.365-377
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• 2022

Mammalian target of rapamycin (mTOR) is a serine-threonine kinase member of the cellular phosphatidylinositol 3-kinase (PI3K) pathway, which is involved in multiple biological functions by transcriptional and translational control. mTOR is a downstream mediator in the PI3K/Akt signaling pathway and plays a critical role in cell survival. In cancer, this pathway can be activated by membrane receptors, including the HER (or ErbB) family of growth factor receptors, the insulin-like growth factor receptor, and the estrogen receptor. In the present work, we congregated an electronic network of mTORC1 built on an assembly of data using natural language processing, consisting of 470 edges (activations/interactions and/or inhibitions) and 206 nodes representing genes/proteins, using the Cytoscape 3.6.0 editor and its plugins for analysis. The experimental design included the extraction of gene expression data related to five distinct types of cancers, namely, pancreatic ductal adenocarcinoma, hepatic cirrhosis, cervical cancer, glioblastoma, and anaplastic thyroid cancer from Gene Expression Omnibus (NCBI GEO) followed by pre-processing and normalization of the data using R & Bioconductor. ExprEssence plugin was used for network condensation to identify differentially expressed genes across the gene expression samples. Gene Ontology (GO) analysis was performed to find out the over-represented GO terms in the network. In addition, pathway enrichment and functional module analysis of the protein-protein interaction (PPI) network were also conducted. Our results indicated NOTCH1, NOTCH3, FLCN, SOD1, SOD2, NF1, and TLR4 as upregulated proteins in different cancer types highlighting their role in cancer progression. The MCODE analysis identified gene clusters for each cancer type with MYC, PCNA, PARP1, IDH1, FGF10, PTEN, and CCND1 as hub genes with high connectivity. MYC for cervical cancer, IDH1 for hepatic cirrhosis, MGMT for glioblastoma and CCND1 for anaplastic thyroid cancer were identified as genes with prognostic importance using survival analysis.

• Korean Journal of Computational Design and Engineering
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• v.1 no.3
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• pp.189-202
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• 1996

Complex geometric shapes can be defined simply and efficiently by combining and operating various surface primitives. These primitives and their intersection curves are used in finite element mesh generation to form an easy and intuitive procedure for finite element modelling of curved surfaces. This paper proposes techniques of automatic mesh generation on surface primitives with arbitrarily shaped boundaries and control curves, which may be created by surface to surface intersection. A method of automatic mesh generation on plane, which was previously developed by the author, has been modified for application to the surface mesh generation. Owing to the mesh generation-wise differences between planes and surfaces, the surfaces should be transformed into conceptual plane so that the modified plane mesh generation method can be applied. Surface development, mapping and mesh reconstruction are the key techniques suggested in this paper. The selection of the technique to apply can be determined automatically on the basis of the developability, existence of singularity and other characteristics of the surfaces on which the mesh is to be generated. The suggested techniques were implemented into parts of mesh generation functions of the finite element software, MacTran. Their validity and practicality were manifested by the actual use of this software.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.1
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• pp.1-10
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• 2004

Adaptive finite element analysis, in which its solution error meets with the user defined allowable error, is recently used to improve the reliability of finite element analysis results. This adaptive analysis is composed of two procedures; one is the error estimation of an analysis result and the other is the reconstruction of finite elements. In the (p-method, an element size is controlled by relocating of nodal positions (r-method) and the order of an element shape function is determined by the hierarchical polynomial (p-method) corresponding to the clement solution error by the enhanced SPR. In order to show the effectiveness and the accuracy of the suggested rp-method, various numerical examples were analyzed and these analysis results were examined by comparing with those obtained by the existed methods.

• Korean Journal of Computational Design and Engineering
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• v.12 no.2
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• pp.118-125
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• 2007

Designer has recently required the supporting system to assist the design steps that are not simple and standardized. But, as it is often the case with many researches, the design support systems have the problems that the functional module's expansion and the flexible connection with the intelligent CAD System are insufficient. In this paper, we present a framework, EDSS Frame (Expanded Design Support System Frame) to improve in its problems. For the implementation of the EDSS Frame, we make the functional modules, the executable files and analyze a characteristic of the functional modules. Finally, we checked the cases that is generated. Through these works, we organize the algorithm of the running process in each cases. A user can make the process through the association of the functional modules. Also, we make the DLL files or algorithms for corresponding in change of the intelligent CAD System. User can make the additional file or algorithm for a new release of the intelligent CAD system. EDSS Frame can be used for the implementation of the design support system on a various fields, and assists a designer with the rapid reconstruction of the design support system through the continuous addition of the functional modules and the redefinition of the running process between the functional modules.