• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.10a
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• pp.229-236
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• 2004

A new three-node triangular shell element based on higher order zig-zag theory is developed for laminated composite shells with multiple delaminations. The present higher order zig-zag shell theory is described in a general curvilinear coordinate system and in general tensor notation. All the complicated curvatures of surface including twisting curvatures can be described in an exact manner in the present shell element because this element is based on geometrically exact surface representation. The displacement field of the proposed finite element includes slope of deflection. which requires continuity between element interfaces. Thus the nonconforming shape function of Specht's three-node triangular plate bending element is employed to interpolate out-of-plane displacement. The present element passes the bending and twisting patch tests in flat surface configurations. The developed element is evaluated through the buckling problems of composite cylindrical shells with multiple delaminations. Through the numerical examples it is demonstrated that the proposed shell element is efficient because it has minimal degrees of freedom per node. The accuracy of the present element is demonstrated in the prediction of buckling loads and buckling modes of shells with multiple delaminations. The present shell element should serve as a powerful tool in the prediction of buckling loads and modes of multi-layered thick laminated shell structures with arbitrary-shaped multiple delaminations.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.69-72
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• 2004

A new three-node triangular shell element based on higher order zig-zag theory is developed for laminated composite shells with multiple delaminations. The present higher order zig-zag shell theory is described in a general curvilinear coordinate system and in general tensor notation. All the complicated curvatures of surface including twisting curvatures can be described in an exact manner in the present shell element because this element is based on geometrically exact surface representation. The displacement field of the proposed finite element includes slope of deflection, which requires continuity between element interfaces. Thus the nonconforming shape function of Specht's three-node triangular plate bending element is employed to interpolate out-of-plane displacement. The present element passes the bending and twisting patch tests in flat surface configurations. The developed element is evaluated through the eigenvalue problems of composite cylindrical shells with multiple delaminations. Through the numerical examples it is demonstrated that the proposed shell element is efficient because it has minimal degrees of freedom per node. The present shell element should serve as a powerful tool in the prediction of natural frequency and modes of multi-layered thick laminated shell structures with arbitrary-shaped multiple delaminations.

• Journal of the Korea Computer Graphics Society
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• v.26 no.3
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• pp.39-48
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• 2020

In this paper, we propose a new technique for filling holes in triangular mesh. First, arbitrary shaped holes are detected. Second, source and target hole patches are generated through triangulation, refinement, fairing, and smoothing. Finally, the shape difference between the two patches is analyzed and a patch with enhanced features is obtained through blending between patches. The effectiveness of the proposed technique is demonstrated by applying the hole filling technique to the triangular mesh model with various shaped holes.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1711-1718
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• 2004

When the tracked vehicle is running on various types of terrain, the physical properties of the interacting ground can be different. In this paper, the interactions between track link and soft soil ground are investigated using static sinkage theory of soil ground. Grouser surfaces of a track link and triangular patches of ground are implemented for contact detection algorithm. Contact force at each segment area of a track link is computed respectively by using virtual work concept. Bekker's static soil sinkage model is applied for pressure-sinkage relationship and shear stress-shear displacement relationship proposed by Janosi and Hanamoto is used for tangential shear forces. The repetitive normal loads of a terrain are considered because a terrain element is subject to the repetitive loading of the roadwheels of a tracked vehicle. The methods how to apply Bekker's soil theory for multibody track system are proposed in this investigation and demonstrated numerically by high mobility tracked vehicle.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.9_10 s.146
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• pp.1359-1368
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• 2005

When we develop the tight-fit 2D pattern from the 3D scan data, segmentation of the 3D scan data into several parts is necessary to make a curved surface into a flat plane. In this study, Garland's method of triangle simplification was adopted to reduce the number of data point without distorting the original shape. The Runge-Kutta method was applied to make triangular patch from the 3D surface in a 2D plane. We also explored the detailed arrangement method of small 2D patches to make a tight-fit pattern for a male body. As results, minimum triangle numbers in the simplification process and efficient arrangement methods of many pieces were suggested for the optimal 2D pattern development. Among four arrangement methods, a block method is faster and easier when dealing with the triangle patches of male's upper body. Anchoring neighboring vertices of blocks to make 2D pattern was observed to be a reasonable arrangement method to get even distribution of stress in a 2D plane.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.4
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• pp.32-40
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• 1994

This paper describes a smooth surface interpolating method of ship hull using a three-dimensional currie net that comes from the mesh curve fairing process. Geometric continuity(($GC^1$) is preserved across the boundary curve between patches. The three-dimensional curve net can have nonrectangular topologies, such as triangular and pentagonal topology. Among the boundary curve interpolation methods, Hermite blended Coons patch, Convex combination, and Gregory patch interpolation method are used to generate the ship hull surface. To check the fairness of the surface, the numerical method of surface/surface intersection problem is adopted. An application to an actual ship hull is given as an example.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.136-142
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• 2010

In this paper, the microstrip antenna for penta-band service is proposed. It is designed for a wide band characteristic based on a monopole line combined with a triangular patch structure which has two slits. Total antenna size is $35\;mm{\times}20\;mm$ and it was fabricated on FR-4 substrate($\varepsilon_r=4.4$) which has $35\;mm{\times}75\;mm{\times}1\;mm$ size and a microstrip line with impedance 50 ohm is used. Experimental result shows the impedance bandwidth($VSWR{\leq}3$) of the proposed antenna operated within GSM/DCS/USPCS/UMTS/Bluetooth frequency band. The resonance frequency of the proposed antenna is 0.92, 1.97, 2.45 GHz and the average gain is -2.18, -0.66, -0.58 dBi. Also, the radiation efficiency is 60, 85, 87%. The fabricated antenna is satisfied with the aimed impedance bandwidth ($VSWR{\leq}3$) in GSM/DCS/ USPCS/UMTS/Bluetooth frequency band.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.5
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• pp.498-508
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• 2001

In this paper, we propose an efficient coding algorithm for the zoom images to find the optimal depth and texture information. The proposed algorithm is the area-based method consisting of two consecutive steps, i) the depth extraction step and ii) the texture extraction step. The X-Y plane of the object space is divided into triangular patches and the depth value of the node is determined in the first step and then the texture of the each patch is extracted in the second step. In the depth extraction step, the depth of the node is determined by applying the block-based disparity compensation method to the windowed area centered at the node. In the second step, the texture of the triangular patches is extracted from the zoom images by applying the affine transformation based disparity compensation method to the triangular patches with the depth value extracted from the first step. To improve the quality of image, the interpolation is peformed on the object space instead of the interpolation on the image plane.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.141-146
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• 2009

A triangular microstrip antenna with T-shaped slits is proposed for tunable dual-band applications. The proposed antenna is designed using chip capacitors as a prototype. From this result the capacitor can be replaced to a varactor diode to control capacitance value. Since the input impedance of the antenna can be varied with the value of the chip capacitors on the T-shaped slits, the resonant frequency may be changed. The return losses are better than 10 dB at the lower band of $0.78{\sim}1.21$ GHz and 20 dB at the upper band of $1.97{\sim}2.17$ GHz, respectively. This antenna has the bandwidth of about 10 MHz and 50 MHz at each band. The peak gains of the antenna yield 0 dBi at the lower band and 3 dBi at the upper band, respectively. Details of the antenna design are described, and its performances are presented and analyzed.

• Journal of the Korea Society of Computer and Information
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• v.18 no.3
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• pp.27-34
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• 2013

A wideband patch antenna fed by an L-strip feeder is studied. The objective of this paper is to design small wideband antenna for 3G and 4G wireless mobile communication service. The enhanced features were confirmed and proved by comparing the proposed antenna with the antennae that have been reported in the relevant literatures. Measurement results confirm that an impedance bandwidth($VSWR{\leq}2$) of 636MHz(32.5%, fo=1,960MHz) is achieved at 3G and 4G frequency band for L-strip-fed triangular patch antenna. In general, probe feed has only the parasitic reactance caused by the probe, which reduces the bandwidth performance of the antenna. The experimental results proved that the effects of improvement could be achieved because the proposed antenna is capable of compensating the parasitic reactance from the feeding mechanism. The studied antenna can be designed easily for extension of array because it has simple structure.