• Korean Journal of Computational Design and Engineering
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• v.13 no.3
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• pp.187-199
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• 2008

This paper describes a C++ class hierarchy of implicit objects for geometry modeling and processing. This class structure provides a software kernel for integrating many various models and methods found in current implicit modeling areas. The software kernel includes primitive objects playing a role of unit element in creating a complex shape, and operator objects used to construct more complex shape of implicit object formed with the primitive objects and other operators. In this paper, class descriptions of these objects are provided to better understand the details of the algorithm or implementation, and its instance examples to show the capabilities of the object classes for constructive shape geometry. In addition, solid modeling system shown as an application example demonstrates that the proposed implicit object classes allow us to carry out modern solid modeling techniques, which means they have the capabilities to extend to various applications.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.565-569
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• 2011

A two-dimensional thermal response and ablation analysis code for predicting charring material ablation and shape change on solid rocket nozzle is presented. For closing the problem of thermo-structural analysis, Arrhenius' equation and Zvyagin's ablation model are used. The moving boundary problem are solved by remeshing-rezoning method. For simulation of complicated thermal protection systems, this method is integrated with a three-dimensional finite-element thermal and structure analysis code.

• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.1
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• pp.11-20
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• 2017

This study investigates the seismic performance of solid reinforced concrete columns with triangular reinforcement details using nonlinear seismic analysis. The developed reinforcement details are economically feasible and rational, and facilitate shorter construction periods. By using a sophisticated nonlinear finite element analysis program, the accuracy and objectivity of the assessment process can be enhanced. Solution of the equations of motion is obtained by numerical integration using Hilber-Hughes-Taylor (HHT) algorithm. The proposed numerical method gives a realistic prediction of seismic performance throughout the input ground motions for several column specimens. As a result, developed triangular reinforcement details were designed to be superior to the existing reinforcement details in terms of required performance.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.226-230
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• 1997

A plasticity theory applicable to powdered metal compaction is briefly summarized and its variational form for the finite element analysis is described. The compaction processes of axisymmetric solid cylinder are simulated. For the analysis of the friction effect of solid cylinder, the investigations were performed for different compact geometries. Highlights of the results for given geometries are reported in terms of transmitted pressure on the lower punch from the upper punch through the compact and maximum density variation within the compacts. General conclusions from these simulation results are : (1) the friction coefficient could be selected from the transmitted force data during the single acting compaction test with the simulated results ; and (2) density variatioins within the compacts are very much dependent of the compact geometry such as the height to diameter ratio and the frictional condition between compact and dies.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.74-79
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• 2000

Integrating a 3D solid modeler with a general purpose FEM code, an automatic nonlinear analysis system of the 3D crack problems has been developed. 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 Delaunay triangulation techniques. The complete finite element(FE) model generated, and a stress analysis is performed. In this system, burden to analysts fur introducing 3D cracks to the FE model as well as fur estimating their fracture mechanics parameters can be dramatically reduced. This paper describes the methodologies to realize such functions, and demonstrates the validity of the present system.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1142-1147
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• 2004

The tooth profile of helical gear that is manufactured by the rack cutter consists of the involute curve and the trochoid curve. However, gear designers are very hard to calculate the exact profile because it needs very complex information about the gear manufacturing. Therefore, the purpose of this study is to develop the automatic generation program for the helical gear using the Solid Works API. First, involute and trochoide coordinates by the rack cutter are calculated. Using the data, Visual Basic program for the helical gear model is coded. This work gives us the quick helical gear modeling and can be used as the modeling for the finite element analysis.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.181-186
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• 2007

UBM (Under Bump Metallurgy) of flip chip assemblies consists of several layers such as the solder wetting, the diffusion barrier, and the adhesion layers. In addition, IMC layers are formed between the solder wetting layers (e.g. Cu, Ni) and the solder. The primary failure mechanism of the solder joints in flip chips is widely known as the fatigue failure caused by thermal fatigues or electromigration damages. Sometimes, the premature brittle failure occurs in the IMC layers. However, these phenomena have thus far been viewed from only experimental investigations. In this sense, this paper presents a method for solid modeling of IMC layers in flip chip assemblies, thus providing a pre-processing tool for finite element analysis to simulate the IMC failure mechanism. The proposed modeling method is CSG-based and can also be applied to the modeling of UBM structure in flip chip assemblies. This is done by performing Boolean operations according to the actual sequences of fabrication processes

• International Journal of CAD/CAM
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• v.2 no.1
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• pp.55-67
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• 2002

In many areas of industry, it is desirable to have fast and reliable systems in order to quickly obtain suitable solid models for computer- aided analyses. Nevertheless it is well known that the data exchange process between CAD modelers and CAE packages can require significative efforts. This paper presents an approach for geometrical data exchange through triangulated boundary models. The proposed framework is founded on the use of STL file specification as neutral format file. This work is principally focused on data exchange among CAD modelers and FEA packages via STL. The proposed approach involves the definition of a topological structure suitable for the STL representation and the development of algorithms for topology and geometry data processing in order to get a solid model suitable for finite element analysis or other computer aided engineering purposes. Different algorithms for model processing are considered and their pros and cons are discussed. As a case study, a prototype modeler which supports an exporting filter for a commercial CAE package has been implemented.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.113-122
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• 2010

A two-dimensional thermal response and ablation analysis code for predicting charring material ablation and shape change on solid rocket nozzle is presented. For closing the problem of thermal analysis, Arrhenius' equation and Zvyagin's ablation model are used. The moving boundary problem are solved by remeshing-rezoning method. For simulation of complicated thermal protection systems, this method is integrated with a three-dimensional finite-element thermal and structure analysis code through continuity of temperature and heat flux.

• Proceedings of the KIEE Conference
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• summer
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• pp.1055-1057
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• 2004

This paper deals with a qualitative analysis of iron loss in Transverse Flux Linear Motor (TFLM). 3D equivalent magnetic circuit network method (EMCNM) is used as an analytical method to get flux density of each element. The total core loss is calculated with the magnetic flux density and core loss curves of an optional material. The results of iron loss analysis can be used as a criterion to decide the manufactural shape such as lamination or solid type core, skew position, etc.