• 한국전산유체공학회:학술대회논문집
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• 2009.11a
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• pp.71-76
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• 2009

The research to predict the resistance performance of the ship using the CFD analysis is increasing. For the CFD numerical analysis the computational mesh, which is proper to computational model, has to be made before the analysis is begun. In the parametric study, even though the deformation of each case is not very sharp, the whole computational mesh should be regenerated according to the conventional way. Hence, lots of effort is needed to repeated mesh generation work. To solve these problems, the automatic mesh generation method using the macro function of commercial CAD program and mesh generation program is introduced in this study. First, in the CAD program, by using the macro function and putting the deformation rate of bow and stern in lengthwise, the repeated modeling work is performed automatically. Next, the generated geometries are read by the mesh generation program and the proper mesh for the geometry is created automatically also using the macro function. The hybrid mesh which has unstructured grid near the bow and stern and structured grid in the remaining part of domain is used. The verification of the developed method is done by applying the method to predict the resistance performance of the podded propulsion cruise ship of the Daewoo Shipbuilding & Marine Engineering (DSME) in the cases of different length of bow and stern and pod set in different position. The author believes that the introduced method can help to make the database to optimize the resistance performance of the ship in various cases can be constructed without difficulty.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.125-129
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• 2009

In this paper automatic 3D wing shape modeling program is introduced. The program is developed in Visual Basic based on Net Framework 3.5 environment by using CATIA COM Library, and it is used together with CATIA system to model 3D wings with or without flaps. With this program users can easily construct wing models by specifying geometry parameters which are usually design variables with the aid of easy-to-use GUI environment, and specifying sectional airfoil data is done either by using analytic shape functions such as NACA series airfoils or by providing input files with point data describing the airfoil shape. When all the input parameters are provided, users can either work further with the model in the CATIA system which would be automatically started by the program or save the resultant model in the format of users choice. Unstructured grid generation program is also briefly described which can make grid generation task for a 3D wing easy and efficient one when used together with the wing modeling program by choosing STL format as the model's output format.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.69-72
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• 2002

The geometry parameter of tool such as rake angle and clearance angle is defined clearly to solve the difference in communication between design and measurement stage. Using the developed simulation program, wheel is properly determined and end mill can be manufactured accurately. The performance test with well defined end mill provides sufficient information to decide optimal geometry. For machining hardened steel, end mills are designed and manufactured. Optimal rake angle and clearance angle is obtained from performance test. A specific software for automatic end mill production is developed far simulation and fur generation of NC code as Cad/CAM system.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.1
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• pp.43-48
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• 2002

This paper describes an automated computer-aided engineering (CAE) system for three-dimensional structures. An automatic finite element mesh-generation technique, which is based on fuzzy knowledge processing and computational geometry techniques, is incorporated into the system, together with a commercial FE analysis code, and a commercial solid modeler. The system allows a geometry model of interest to be automatically converted to different FE models, depending on the physical phenomena of the structures to be analyzed, i.e., electrostatic analysis, stress analysis, modal analysis, and so on. Also, with the aid of multilayer neural networks, the present system allows us to obtain automatically a design window in which a number of satisfactory design solutions exist in a multi-dimensional design parameter space. The developed CAE system is successfully applied to evaluate an electrostatic micromachines.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.711-715
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• 1996

This paper describes an automated computer-aided engineering (CAE) system for micromachines whose size range 10 to 10$^3$${\mu}{\textrm}{m}$. An automatic finite element mesh generation technique, which is based on the fuzzy knowledge processing and computational geometry techniques, is incorporated into the system, together with one of commercial finite clement (FE) analysis codes, MARC, and one of commercial solid modelers, Designbase. The system allows a geometry model of concern to be a automatically converted to different FE models, depending on physical phenomena to be analyzed, i.e. electrostatic analysis, stress analysis, modal analysis and so on. The FE analysis models are then exported to the FE analysis code, and then analyses are performed. This system is successfully applied to an electrostatic micro actuator.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.2
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• pp.171-176
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• 2002

This paper describes a new automated analysis system for model plane engine. An automatic finite element (FE) mesh generation technique, which is based on the fuzzy knowledge processing and computational geometry technique, is incorporated into the system, together with one of commercial FE analysis codes, ANSYS, and one of commercial solid modelers, Designbase, The system allows a geometry model of concern to be automatically converted to different FE models, depending on physical phenomena of plane engine to be analyzed, i.e. deformation analysis, thermal analysis and so on. The FE models are then automatically analyzed by the FE analysis code. Among a whole process of analysis, the definition of a geometry model, the designation of local node patterns, the assignment of material properties and boundary conditions onto the geometry model are only the interactive processes to be done by a user. The interactive operations can be processed in a few minutes. The other processes which are time consuming and labour-intensive in conventional CAE systems are fully automatically performed in a personal computer environment. The proposed analysis system is successfully applied to evaluate a model plane entwine.

• Korean Journal of Computational Design and Engineering
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• v.4 no.2
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• pp.153-161
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• 1999

An atomatic mesh generation scheme with unstructured quadrilateral elements on trimmed surfaces has been developed. Trimmed surfaces are often encountered in modeling of structures with complex shapes such as aircrafts, automobile structures, pressure vessels and etc. For unstructured mesh generation with quadrilateral elements, a domain decomposition algorithm employing loop operators has been used. Mesh generation on trimmed surface is performed in three steps. First, trimmed surfaces with holes or cuts are transformed to th largest projection planes in which the meshes are constructed. The constructed meshes are transformed to the u-v parametric plane and then finally to the original 3D surfaces. Th exact locations of holes or cuts in projection planes are determined by the Newton-Raphson method. Sample meshes are constructed to demonstrate the effectiveness of the proposed algorithm.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.6
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• pp.1004-1014
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• 2001

The fully automatic algorithm from initial finite element mesh generation to remeshing in two dimensional geometry is introduced using bubble packing method (BPM) for finite element analysis. BPM determines the node placement by force-balancing configuration of bubbles and the triangular meshes are made by Delaunay triangulation with advancing front concept. In BPM, we suggest two node-search algorithms and the adaptive/recursive bubble controls to search the optimal nodal position. To use the automatically generated mesh information in FEA, the new enhanced bandwidth minimization scheme with high efficiency in CPU time is developed. In the remeshing stage, the mesh refinement is incorporated by the control of bubble size using two parameters. And Superconvergent Patch Recovery (SPR) technique is used for error estimation. To verify the capability of this algorithm, we consider two elasticity problems, one is the bending problem of short cantilever beam and the tension problem of infinite plate with hole. The numerical results indicate that the algorithm by BPM is able to refine the mesh based on a posteriori error and control the mesh size easily by two parameters.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.24-27
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• 2003

High-resolution satellite images at sub-5m footprint are becoming increasingly available to the earth observation community and their respective clients. The related cameras are all using linear array CCD technology for image sensing. The possibility and need for accurate 3D object reconstruction requires a sophisticated camera model, being able to deal with such sensor geometry. We have recently developed a full suite of new methods and software for the precision processing of this kind of data. The software can accommodate images from IKONOS, QuickBird, ALOS PRISM, SPOT5 HRS and sensors of similar type to be expected in the future. We will report about the status of the software, the functionality and some new algorithmic approaches in support of the processing concept. The functionality will be verified by results from various pilot projects. We put particular emphasis on the automatic generation of DSMs, which can be done at sub-pixel accuracy and on the semi-automated generation of city models.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2183-2188
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• 2009

This paper describes an automatic mesh generation system for finite element analysis of three-dimensional cracks. It is consisting of fuzzy knowledge processing, bubble meshing and solid geometry modeler. This novel mesh generation process consists of three sub-processes: (a) definition of geometric model, i.e. analysis model, (b) generation of bubbles, and (c) generation of elements. One of commercial solid modelers is employed for three-dimensional crack structures. Bubble is generated if its distance from existing bubble points is similar to the bubble spacing function at the point. The bubble spacing function is well controlled by the fuzzy knowledge processing. The Delaunay method is introduced as a basic tool for element generation. Practical performances of the present system are demonstrated through several mesh generations for 3D cracks.