• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.153-155
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• 1994

Electric machines such as motors which have moving parts are desgined for producing mechanical force or torque. The accurate calculation of electromagnetic force and torque is important in the design these machines, Electromagnetic force calculation method using the results of Finite Element Method(FEM) has been presented variously in 2-D problems. Typically the Maxwell's Stress Tensor method and the method of virtual work are used. In the problems including current source, magnetic vector potentials(MVP) have mostly been used as an unknown variables for field analysis by numerical method; e, g. FEM. This paper, thus, introduces both methods using MVP in 3-D case. To verify the usefulness of presented methods, a solenoid model is chosen and analyzed by 3-D and axisymmetrical FEM. In each case, the calculated force are tabulated for several mesh schemes.

• Annual Conference of KIPS
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• 2022.05a
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• pp.708-711
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• 2022

본 논문은 3D 프린팅 출력 성공률을 높이기 위해 GPU를 이용한 대용량 3D 메쉬 모델에 대한 병렬 자체충돌 검사 방법을 제안한다. 강인하고 견고한 자체 충돌 검사를 위해 분리축 검사, 삼각형-삼각형 교차 검사, 메쉬 연결성 검사, 대용량 메쉬를 위한 분할 처리 기법의 절차를 제안한다. 이러한 자체 충돌 검사를 빠르게 수행하기 위하여 GPU 기반 병렬처리 구현 방법을 제시한다.

• Electronics and Telecommunications Trends
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• v.21 no.4 s.100
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• pp.12-21
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• 2006

3차원 메시 모델은 컴퓨터 그래픽스, 애니메이션, 3D 모델링, CAD, 3D 게임 등의 다양한 응용 분야에서 광범위하게 사용되고 있다. 그러나, 현실감을 줄 수 있는 고해상도의3차원 모델은 그 정보량의 방대함으로 인해 처리, 저장, 전송 등에 있어 여러 가지 어려움이 따른다. 따라서, 이를 효율적으로 압축하여 저장 및 전송하기 위한 3차원 메시 모델 부호화 기술이 연구되어 왔다. 본 고에서는 3차원 메시 부호화 기술에 대한 연구 개발 동향과 이에 대한 표준화 동향을 소개한다. 또한, 3차원 메시 부호화 기술과 관련하여 ETRI에서 연구중인 정점 및 면 순서 정보 부호화 기술과 텍스처 좌표 부호화 기술의 내용과 이에 대한 연구 활동 현황을 요약하고, 주요 이슈 논의 및 향후 전망에 대해 간략히 살펴보고자 한다.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.600-605
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• 2009

A general purpose viscous flow solver Ansys CFX is used to study a Savonius type wave energy converter in a 3D numerical viscous wave tank. This paper presents the results of a computational fluid dynamics (CFD) analysis of the effect of blade configuration on the performance of 3 bladed Savonius rotors for wave energy extraction. A piston-type wave generator was incorporated in the computational domain to generate the desired incident waves. A complete OWC system with a 3-bladed Savonius rotor was modeled in a three dimensional numerical wave tank and the hydrodynamic conversion efficiency was estimated. The flow over the rotors is assumed to be two-dimensional (2D), viscous, turbulent and unsteady. The CFX code is used with a solver of the coupled conservation equations of mass, momentum and energy, with an implicit time scheme and with the adoption of the hexahedral mesh and the moving mesh techniques in areas of moving surfaces. Turbulence is modeled with the k.e model. Simulations were carried out simultaneously for the rotor angle and the helical twist. The results indicate that the developed models are suitable to analyze the water flows both in the chamber and in the turbine. For the turbine, the numerical results of torque were compared for all the cases.

• Journal of the Korean Geotechnical Society
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• v.23 no.1
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• pp.67-76
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• 2007

Flat DMT penetration was analyzed using a finite element model based on a large strain formulation. The ABAQUS/Explicit, a commercial finite element method, was used to study the flat DMT penetration in soils. Then, because the very large mesh distortion occurred due to the penetration of flat DMT, the adaptive meshing technique was utilized to maintain a high quality mesh configuration. The undrained shear strength obtained from the flat DMT is estimated using only the horizontal stress index ($K_{D}$) and so it became necessary to examine using the analysis results obtained from the penetration of the flat DMT. Analysis results show that in normally consolidated region of $K_{D}=2$, the results obtained from the correlations proposed by Marchetti show good agreement with those estimated from the finite element method. The present analysis also shows that in overconsolidated region of $K_{D}>2$, the results obtained from the relationships proposed by Kamei and Iwasaki show good agreement with those provided by the penetration analysis.

• Korean Journal of Computational Design and Engineering
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• v.20 no.4
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• pp.385-400
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• 2015

ISO 15926 is an international standard for the integration and sharing of plant lifecycle data. Plant 3D design data typically consist of logical configuration, equipment specifications and ports, and 3D shape data. This paper presents the method for the ISO 15926-based integration of plant 3D design data. For this, reference data (class, attribute, and template) of ISO 15926 were extended to describe plant 3D design data. In addition to the data model extension, a plant design information integration platform which reads plant 3D design data in ISO 15926 and displays 3D design information was developed. Finally, the prototype platform is verified through the experiment of loading and retrieving plant 3D design data in ISO 15926 with the platform.

• Journal of Digital Convergence
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• v.11 no.8
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• pp.205-212
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• 2013

In this paper, we present a procedural modeling algorithms to create Korean traditional stone fence using the fractal subdivision. The main process of the algorithm is to get the next step mesh by subdividing each triangle in the previous step triangular mesh. This process is repeated recursively. Dividing each triangle into four sub-triangles after choosing a random point on each side of the triangle and moving each vertices in the normal direction with random perturbations make the bumpy appearance of stone fences. In each step we remove flat vertices which does not influence the shape of the stone. The discrete curvature determines the flatness of a vertex. New triangles whose vertices are the vertices around the removed vertex are added to make a triangular mesh.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.545-560
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• 2008

O Source import ㅁDirect import form Nastran, ANSYS ㅁDirect import of all the RPM from the files containing the structural results O Solver ㅁDirect computation of all RPM (multiple load case): one matrix resolution with multiple RHS ㅁEfficient solvers (MUMPS, SPARSE, Iterative) ㅁFrequency parallelisms available for very large problems O In practice ㅁSmall problems run on a desktop ㅁLarge problems can exceed 3kHz on a car engine O Easy to mesh ㅁ3D model created in a few minutes thanks to the unequal meshes. O And all Actran standard features

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.3
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• pp.1-8
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• 2017

Tool path generation is a part of process planning in 3D printing. This is done before actual printing by a computer rather than an AM machine. The mesh geometry of the 3D model is sliced layer-by-layer along the Z-axis and tool paths are generated from the sliced layers. Each 2-dimensional layer can have two types of printing paths: (i) shell and (ii) infill. Shell paths are made of offset loops. During shell generation, twists can be produced in offset loops which will cause twisted tool paths. As a twisted tool path cannot be printed, it is necessary to remove these twists during process planning. In this research, An algorithm is presented to remove twists from the offset loops. To do so the path segments are traversed to identify twisted points. Outer offset loops are represented in the counter-clockwise segment order and clockwise rotation for the inner offset loop to decide which twisted loop should be removed. After testing practical 3D models, the proposed algorithm is verified to use in tool path generation for 3D printing.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.396-401
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• 2004

In this paper, a 1MW HAWT(FIL-1000) rotor blade has been designed by BEMT(Blade Element Momentum Theory) with Prandtl's tip loss. Also, a 3-D flow and performance analysis on the FIL-1000 rotor blade has been carried out by using the 3-D Navier-Stokes commercial solver (CFX-5.7) to provide more efficient design techniques to the large-scale HAWT engineers. The rated power and itsapproaching wind velocity at design point (TSR=7.5) are 1MW and 9.99m/s respectively. The rotor diameter is 54.5m and the rotating speed is 26.28rpm. Airfoils such as FFA W-301, DU91-W-250, DU93-W-210, NACA 63418, NACA 63415 consist of the rotor blade from hub to tip. Recent CFX version, 5.7 was adopted to simulate 3-D flow field and to analyze the performance characteristics of the rotor blade. Entire mesh node number is about 730,000 and it is generated by ICEM-CFD to achieve better mesh quality The predicted maximum power occurringat the design tip speed ratio is 931.45kW. Approaching to the root, the inflow angle becomes large, which causesthe blade to be stalled in the region. Therefore, k-$\omega$ SST turbulence model was used to predict the quantitative flow information more accurately. Application of commercial CFD code to optimum blade design and performance analysis was proved to be more effective environment to HAWT blade designers.