• Journal of Periodontal and Implant Science
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• v.43 no.4
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• pp.160-167
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• 2013

Purpose: This study examined the factors that can be associated with the appearance of the interproximal papilla. Methods: One hundred and forty-seven healthy interproximal papillae between the maxillary central incisors were examined. For each subject, a digital photograph and periapical radiograph of the interdental embrasure were taken using a 1-mm grid metal piece. The following parameters were recorded: the amount of recession of the interproximal papilla, contact point-bone crest distance, contact point-cemento-enamel junction (CEJ) distance, CEJ-bone crest distance, inter-radicular distance, tooth shape, embrasure space size, interproximal contact area, gingival biotype, papilla height, and papilla tip form. Results: The amount of recession of the interproximal papilla was associated with the following: 1) increase in contact point-bone crest, contact point-CEJ, and CEJ-bone crest distance; 2) increase in the inter-radicular distance; 3) triangular tooth shape; 4) decrease in the interproximal contact area length; 5) increase in the embrasure space size; and 6) flat papilla tip form. On the other hand, the amount of gingival recession was not associated with the gingival biotype or papilla height. In the triangular tooth shape, the contact point-bone crest distance and inter-radicular distance were longer, the interproximal contact area length was shorter, and the embrasure space size was larger. The papilla tip form became flatter with increasing inter-radicular distance and CEJ-bone crest distance. Conclusions: The relative position of the interproximal papilla in healthy subjects was associated with the multiple factors and each factor was related to the others. A triangular tooth shape carries a higher risk of recession of the interproximal papilla because the proximal contact point is positioned more incisally and the bone crest is positioned more apically. This results in an increase in recession of the interproximal papilla and flat papilla tip form.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.6
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• pp.629-639
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• 2018

In this study, the application of the single beam echosounder and multi beam echosounder was analyzed for the Youngsan river, from the Juksanbo to the Juksan bridge, length of 840m, width 230m and area $0.16km^2$. A single beam echosounder and a multi beam echosounder are mounted on an USV (Unmanned Surface Vessel), and each data is acquired. Then, TIN (Triangular Irregular Network) is created and the grid depth of 10m intervals is extracted. The grid depth of the single beam echo sounder and the grid depth of the multi beam echo sounder were overlapped to compare the two data. As a result of analysis using 5,024 data, the mean depth difference was 0.0319m and the standard deviation was 2.4095m. The river bed shape was similar to each other. If the multi-beam echo sounder is regarded as the standard, the volume difference of the stream is $161,882m^3$. With a multi-beam echo sounder installed, the operating distance increased by approximately 55% to 4595.85m, and the operating time increased by approximately 59% to approximately 47%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.8
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• pp.1337-1345
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• 2000

In spite of the advantages of lightweight, low profile, and mass productions, microstrip array antenna has inherently the scan blindness problems in case of wide angle scan. And this scan blindness can be overcome by using cavity-backed microstrip radiator. In this paper, we presented the algorithm of analyzing skewed cavity-backed microstrip array and verified the validity of the proposed numerical results with those of reference papers. Finally, we show the effect of cavity-backed and skewed grid array structure.

• Journal of electromagnetic engineering and science
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• v.19 no.1
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• pp.6-12
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• 2019

An IE-FFT algorithm is implemented and applied to the electromagnetic (EM) solution of perfect electric conducting (PEC) scattering problems. The solution of the method of moments (MoM), based on the magnetic field integral equation (MFIE), is obtained for PEC objects with closed surfaces. The IE-FFT algorithm uses a uniform Cartesian grid to apply a global fast Fourier transform (FFT), which leads to significantly reduce memory requirement and speed up CPU with an iterative solver. The IE-FFT algorithm utilizes two discretizations, one for the unknown induced surface current on the planar triangular patches of 3D arbitrary geometries and the other on a uniform Cartesian grid for interpolating the free-space Green's function. The uniform interpolation of the Green's functions allows for a global FFT for far-field interaction terms, and the near-field interaction terms should be adequately corrected. A 3D block-Toeplitz structure for the Lagrangian interpolation of the Green's function is proposed. The MFIE formulation with the IE-FFT algorithm, without the help of a preconditioner, is converged in certain iterations with a generalized minimal residual (GMRES) method. The complexity of the IE-FFT is found to be approximately $O(N^{1.5})$and $O(N^{1.5}logN)$ for memory requirements and CPU time, respectively.

• Journal of Mechanical Science and Technology
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• v.20 no.12
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• pp.2218-2229
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• 2006

A conservative finite-volume numerical method for unstructured grids with the cell-centered method has been developed for computing flow and heat transfer by combining the attractive features of the existing pressure-based procedures with the advances made in unstructured grid techniques. This method uses an integral form of governing equations for arbitrary convex polyhedra. Care is taken in the discretization and solution procedure to avoid formulations that are cell-shape-specific. A collocated variable arrangement formulation is developed, i.e. all dependent variables such as pressure and velocity are stored at cell centers. For both convective and diffusive fluxes the forms superior to both accuracy and stability are particularly adopted and formulated through a systematic study on the existing approximation ones. Gradients required for the evaluation of diffusion fluxes and for second-order-accurate convective operators are computed by using a linear reconstruction based on the divergence theorem. Momentum interpolation is used to prevent the pressure checkerboarding and a segregated solution strategy is adopted to minimize the storage requirements with the pressure-velocity coupling by the SIMPLE algorithm. An algebraic solver using iterative preconditioned conjugate gradient method is used for the solution of linearized equations. The flow analysis code (PowerCFD) developed by the present method is evaluated for its application to several 2-D structured-mesh benchmark problems using a variety of unstructured quadrilateral and triangular meshes. The present flow analysis code by using unstructured grids with the cell-centered method clearly demonstrate the same accuracy and robustness as that for a typical structured mesh.

• Journal of Korea Water Resources Association
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• v.41 no.11
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• pp.1123-1133
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• 2008

It needs to conceptualize watershed with triangular or rectangular elements and to analyze the changes in hydrological components of each element for distributed modeling of rainfall-runoff process. This study is the network analysis of watershed grid for flow routing occurred in each element when analyzing rainfall-runoff process by one-dimensional kinematic wave equation. Single flow direction from D8-method(deterministic eight-neighbors method) is used, and the information of flow direction and flow accumulation are used to determine the computation order of each element. The application theory of finite volume method is suggested for each flow direction pattern between elements, and it is applied it to calculate the flow of each grid. Network analysis method from this study is applied to GRM(Grid based Rainfall-runoff Model) which is physically based distributed rainfall-runoff model, and the results from simplified hypothetical watersheds are compared with $Vflo^{TM}$ to examine the reasonability of the method. It is applied to Jungrangcheon watershed in Han river for verification, and examination of the applicability to real site. The results from Jungrangcheon watershed show good agreement with measured hydrographs, and the application of the network analysis method to real site is proper.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.11
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• pp.52-62
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• 1995

We developed a two-dimensional numerical simulator which can analyze the electrical as well as optical characteristics and evaluate the detection performances of self-signal processing infrared detectors. It solves the poisson equation and the electron, hole current continuity equations including the optical generation and recombination models. To speed up convergency rate. the Newton algorithm is used. Automatic triangular grid generator make it easy to simulate the devices with the various read-out geometries. This simulator can show the variation of spatial resolution which is caused by the transit velocity and transit time dispersion in bifurcate and horn geometries respectively. Also, we calculated the responsivity, noise, and detectivity in respect of the applied electric field and background field-of-view. The results obtained from simulation correspond to those of experiments, and it is verified that horn read-out geometry has the superior spatial resolution and detection performance to bifurcate geometry.

• Journal of Industrial Technology
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• v.17
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• pp.43-50
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• 1997

Local administration is closely related with intention of residents. Especially, a plan item is closely related with life of residents. Therefore, it has to be logical and objective solution for opinion convergence. Decision of opinion has to be in a triangular position standard and stand in a trio of criteria in standard. But, opinion convergence of residents very difficult. Recently, the technique of GIS presents method for oponion convergence with logical and objective and scientifically solution. And, this study present method for decision of intention to a complex element with GRID and NETWORK techniques of GIS. This study present optimun site of constructure with the GIS technique in consideration of a side face of transportation, technical, social economy and environments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.9
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• pp.1814-1821
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• 2002

NC cutting simulation is an important factor in the development of products. The geometric modelling of cutter swept surface should be done in NC cutting simulation. A part of cutter swept surface is a ruled surface blended with silhouette curve and cutter path. Finding an intersection point between cutter swept surface and a line is one of major problems in Z-map based cutting simulation. In this paper, cutter swept surface is defined parametrically and it's intersection point with Z-map is found in an exact form. Triangular grid Z-map based 3-axis NC cutting simulation is performed.

• Journal of Mechanical Science and Technology
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• v.18 no.12
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• pp.2190-2203
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• 2004

A combined procedure for two-dimensional Delaunay mesh generation algorithm and an adaptive remeshing technique with higher-order compressible flow solver is presented. A pseudo-code procedure is described for the adaptive remeshing technique. The flux-difference splitting scheme with a modified multidimensional dissipation for high-speed compressible flow analysis on unstructured meshes is proposed. The scheme eliminates nonphysical flow solutions such as the spurious bump of the carbuncle phenomenon observed from the bow shock of the flow over a blunt body and the oscillation in the odd-even grid perturbation in a straight duct for the Quirk's odd-even decoupling test. The proposed scheme is further extended to achieve higher-order spatial and temporal solution accuracy. The performance of the combined procedure is evaluated on unstructured triangular meshes by solving several steady-state and transient high-speed compressible flow problems.