• The Journal of the Acoustical Society of Korea
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• v.20 no.8
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• pp.3-11
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• 2001

This paper describes an implementation of inverse filter using SVD in order to recover the input in multi-channel system. The matrix formulation in SISO system is extended to MIMO system. In time and frequency domain we investigates the inversion of minimum phase system and non-minimum phase system. To execute an effective inversion of non-minimum phase system, SVD is introduced. First of all we computes singular values of system matrix and then investigates the phase property of system. In case of overall system is non-minimum phase, system matrix has one (or more) very small singular value (s). The very small singular value (s) carries information about phase properties of system. Using this property, approximate inverse filter of overall system is founded. The numerical simulation shows potentials in use of the inverse filter.

• Journal of KIISE:Software and Applications
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• v.34 no.5
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• pp.465-475
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• 2007

With the spread of Internet, web users express their daily life by articles, pictures and cartons to recollect personal memory or to share their experience. For the easier recollection and sharing process, this paper proposes diverse cartoon generation methods using the landmark lists which represent the behavior and emotional status of the user. From the priority and causality of each landmark, critical landmark is selected for composing the cartoon scenario, which is revised by story ontology. Using similarity between cartoon images and each landmark in the revised scenario, suitable cartoon cut for each landmark is composed. To make cartoon story more diverse, weather, nightscape, supporting character, exaggeration and animation effects are additionally applied. Through example scenarios and usability tests, the diversity of the generated cartoon is verified.

• The Korean Journal of Medicine
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• v.99 no.2
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• pp.104-110
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• 2024

Helicobacter pylori (H. pylori) is a bacterium that colonizes the human stomach, leading to various gastrointestinal diseases including gastritis, peptic ulcers, and gastric cancer. There is no gold standard test that relies entirely on one method in H. pylori diagnosis. We must be aware of the pros and cons of various testing methods to perform an appropriate test according to the situation. Accurate diagnosis and eradication therapy are essential for disease management. Diagnostic methods include invasive techniques like tissue biopsy and rapid urease test, as well as non-invasive tests such as urea breath test, serology test, and stool antigen test. Each method has its advantages and limitations, requiring careful consideration in clinical practice. Understanding these diagnostic tools is crucial for effective H. pylori management and prevention of associated complications.

• Journal of Advanced Navigation Technology
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• v.7 no.2
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• pp.180-190
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• 2003

By using accurate closed-form Green's functions obtained from real-axis integration method, the full-wave analysis of CPW discontinuities are performed in space domain. In solving MPIE(Mixed Potential Integral Equation), Galerkin's scheme is employed with the linear basis functions on the triangular elements in air-dielectric boundary. In the singular integral arising when the observation point and source point coincides, the surface integral is transformed into the line integral and the integral is evaluated by regular integration. By using the Green's function from the real-axis integration method, the discontinuities are characterized accurately.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.496-500
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• 1997

This paper describes an automated system for analyzing the stress intensity factors(SIFs) of three-dimensional (3D) cracks. A geometry model, i.e.a solid containing one or several 3D cracks is defined. Several distributions of local node density are chosen, and then automatically superposed on one another over the geometry model by using the fuzzy knowledge processing. Nodes are generated by the bucketing method, and ten-noded quadratic tetrahedral solid elements are generated by the Delauuay triangulation techniques. The singular elements such that the mid-point nodes near crack fornt are shifted at the quarter-points are automatically placed along the 3D crack front. THe complete finite element (FE) model generated, i.e the mesh with material properties and boundary conditions is given to one of the commercial FE codes, and a stress analysis is performed. The SIFs are calculated using the displacement extrapolation method. To demonstrate practical performance of the present system, a semi- elliptical surface crack in a plate subjected to tension is solved.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.1
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• pp.14-28
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• 1992

For a planar curve-sided paned with constant or linear density distributions of source or doublet in the singularity methods, Cantaloube and Rehbach(1986) show that the surface integral can be transformed into contour integral by using Stokes' formulas. As an extension of their formulations, this paper deals with a planar polygonal panel for which we derive the closed-forms of the potentials and the velocities induced by the singularity distributions. Test calculations show that the analytical evaluation of the closed-forms is superior to numerical integration(suggested by Cantaloube and Rehbach) of the contour integral. The compact and explicit expressions may produce accurate values of matrix elements of simultaneous linear equations in the singularity methods with much reduced computer tiome.

• Journal of The Korean Association For Science Education
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• v.34 no.4
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• pp.393-406
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• 2014

Pedagogical Content Knowledge (PCK) is intrinsically domain/topic-specific knowledge for teachers' expertise. On the basis of this idea about PCK, we investigated in-service science teachers' topic-specific PCK on the unit of stars and universe in terms of teachers' knowledge and practices. We observed four middle school science teachers' classes for eighth graders, and took the videos of the classes. The topics of the classes covered constellation, annual parallax and the distance of stars, and the expansion of the universe. We also examined the teachers' pedagogical thinking through video stimulated recall interviews. In addition, we developed a protocol to analyze the levels of participant teachers' PCK and the characteristics revealed in their classes on each topic. Results of the study showed that the participant teachers' level of PCK varied across the topics of classes and the sub-components of PCK. We also identified teaching orientations played key roles in shaping overall characteristics of their PCK. Moreover, astronomical thinking such as spatial thinking and system thinking, was not appropriately embedded as the specific practices into the astronomical concepts in their instructions. We discussed the implications on the progressions of teachers' PCK in terms of their professional development.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.4
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• pp.38-45
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• 1998

It is a tedious and excessive time consuming process to model the local area of crack tip part of structures in calculation of stress intensity factors by FEM. So, in this paper, the hybrid method of FEM and BEM approach was formulated to overcome this type of problems. The multi-domained BEM was adopted to simplify the modelling process of complex geometry and singularity characteristics of crack tip part and the ordinary FEM modelling was used in the rest part. The example calculations shows very good results compared with analytic solutions and other numerical method.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.803-810
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• 1992

With increases in the rotational speed of hydraulic machine, studies on the hydrodynamic characteristics of supercavitating cascade are important on the view of flow analysis and design of fluid machinery. In the present paper, the complex functions of nonlinear theory corresponding to the flow of supercavitating cascade can be obtained by distributing singulary singulary points such as sources, vortexes and doublets on hydrofoil and free streamline. The numerical calculations on the closed wake model and semi-closed wake model are carried out in order to show the flow characteristics around the supecavitating cascade with finite with finite cavity length. As the result of this study, the flow characteristics such as lift, drag and cavitation coefficients are predicted by the flow conditions of supercavitating cascade in the fluid machinery.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.4
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• pp.58-65
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• 1992

In this paper, wave resistance for a submerged body is calculated by a higher order panel method. The Neumann-Kelvin problem is solved by the source or normal dipole distribution method. The body surface is represented by a bicubic B-spline and the singularity strengths are approximated by a bilinear form. The results calculated by the higher order panel method are compared with those by the lowest order panel method developed by Hess & Smith. The convergence rate of the higher order panel method is much better than the lowest order panel method. But the wave resistance calculated by the higher order panel method still shows discrepancy with an analytic solution at low Froude number like that by the lowest order panel method.