• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.1
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• pp.43-53
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• 2008

Surface edge crack in transversely isotropic piezoelectric material is analyzed. The concentrated antiplane mechanical and inplane electrical loadings are applied to an arbitrary point of the surface, where the impermeable crack boundary condition is imposed. Using Mellin transform the problem is formulated, from which Wiener-Hopf equations are derived. By solving the equations the solution is obtained in a closed form. Mechanical and electric intensity factors and energy release rate are obtained and discussed. This problem could be used as a Green's function to generate the solutions of other problems with the same geometry but of different loading conditions.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.548-553
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• 2000

A new design of cylindrical capacitive sensor(CCS) for the displacement measurement of precision active magnetic bearing(AMB) spindle is presented in this paper. This research is motivated by the problem that existing 4-segment CCS is still sensitive to the $3^{rd}$ harmonic component of the geometric errors of a rotor. The procedure of designing new CCS starts from the modeling and error analysis of CCS. The angular size of CCS is set up as a design parameter, and new 8-segment CCS is introduced to possess an arbitrary angular size. The optimum geometry of CCS to minimize the effect of geometric errors is determined through minimum norm approach. Experimental results with test rotors have confirmed the improvement in geometric error suppression.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.22-23
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• 2011

As device dimensions shrink, it is increasingly important to develop fabrication methods that can create sub-15 nm features of regular or arbitrary geometry in a rapid, parallel, and efficient process. This talk will discuss approaches based on self-assembling hybrid polymers containing Si. The thin films of those materials systems can generate well-ordered periodic arrays of dots or lines. For achieving, long-range ordering, it is helpful to use lithographically-defined templates, which are in general much larger than the length-scale of self-assembled nanostructures. For example, the self-assembly of polymer nanostructures can easily be templated using an array of nanoscale topographical elements that act as guiding templates or surrogates for one of two microdomains. The solvent-vapor-induced tunability of pattern dimension and morphology will be discussed as well. Those material systems can excellently serve for high-precision self-assembly that can provide good resolution, reliability, and controllability and be considered as an option for a future nanomanufacturing technology.

• Journal for History of Mathematics
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• v.16 no.2
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• pp.55-70
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• 2003

This study investigated tile intuitive level of justification in geometry, as the former step to the aximatization, with concrete examples. First, we analyze limitations that the axiomatic method has in tile context of discovery and the educational situation. This limitations can be supplemented by the proper use of the intuitive method. Then, using the histo-genetic analysis, this study shows the process of the development of geometrical thought consists of experimental, intuitive, and axiomatic steps. The intuitive method of proof which is free from the rigorous axiom has an advantage that can include the context of discovery. Finally, this paper presents the issue of intuitive proving that the three angles of an arbitrary triangle amount to 180$^{\circ}$, as an example of the local systematization.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.295-302
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• 2001

In the present study, we propose the framework which directly links shell finite element to the surface geometric modeling. For the development of a robust shell element, partial mixed variational functional is provided. The NURBS is used to generate the general free form of parameterized shell surfaces. Employment of NURBS makes shell finite element handle the arbitrary geometry of the smooth shell surfaces. The proposed shell finite element model linked with NURBS surface representation provides efficiency for design and analysis and can be directly extended to surface shape optimization problems in future work.

• Journal of Powder Materials
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• v.9 no.4
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• pp.245-250
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• 2002

In this paper we presented numerical method for the simulation of powder injection molding filling process, which is one of the key processes in powder injection molding. Rheological properties of powder binder mixture such as slip phenomena and yield stress were introduced into the numerical analysis model of powder injection molding filling simulation. Numerical model can be classified into two types. One is 2.5D model which can be introduced to a arbitrary thin geometry and the other is full 3D model which can be applied to a general 3D shape. For 2.5D model we showed the validity of our CAE system with several verification examples. Finally we suggested flow analysis model for 3D powder injection molding filling simulation.

• Journal of KSNVE
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• v.3 no.3
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• pp.271-278
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• 1993

Acoustic characteristics of silencer system are affected by various geometric parameters such as cross sectional geometry, size of chamber, and location of inlet-outlet port. It is impossible to obtain exact solutions of the equations of acoustic wave propagation except few simple cases. So, we resort to numerical techniques to analyze performance of acoustic system. In this work, finite element formulation has been obtained to predict transmission loss of an arbitrary 3-dimensional muffler in the presence of mean flow of low mach number. The effect of the degree of the ellipticity of expansion chambers on the transmission loss has been studied using the resulting finite element equation.

• Proceedings of the Korea Society for Simulation Conference
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• 1998.10a
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• pp.204-208
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• 1998

The fundamental issues to evaluate machine tool's performance through simulation pertain to the physical models of the machine tool itself and of process while the practical problems are related to the development of the modular software structure. It allows the composition of arbitrary machine/process models along with the development of programs to evaluate each state of machining process. Surface roughness is one of the fundamental factors to evaluate machining process and performance of machine tool, but it is not easy to evaluate surface roughness due to its tribological complexity. This paper presents an algorithm to calculate surface roughness considering cutting geometry, cutting parameters, and contact dynamics of cutting between tool and workpiece as well as tool wear in turning process. The designed virtual machining system can be used to evaluate the surface integrity of a turned surface during the design and process planning phase for the design for manufacturability analysis of the concurrent engineering.

• Journal of the Korea Society for Simulation
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• v.8 no.1
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• pp.19-33
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• 1999

The fundamental issues to evaluate machine tools performance through simulation pertain to the physical models of the machine tool itself and of process while the practical problems are related to the development of the modular software structure. It allows the composition of arbitrary machine/process models along with the development of programs to evaluate each state of machining process. Surface roughness is one of the fundamental factors to evaluate machining process and performance of machine tool, but it is not easy to evaluate surface roughness due to its tribological complexity. This paper presents an algorithm to calculate surface roughness considering cutting geometry, cutting parameters, and contact dynamics of cutting between tool and workpiece as well as tool wear in turning process. This proposed algorithm could be used in the designed virtual machining system. The system can be used to evaluate the surface integrity of a turned surface during the design and process planning phase for the design for manufacturability analysis of the concurrent engineering.

• Korean Journal of Computational Design and Engineering
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• v.3 no.4
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• pp.293-303
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• 1998

The objective of this study is to develop a PC level freeform surface modeling system which explicitly represents information of part geometry. Surface modeler uses nonuniform rational B-spline (NURBS) function with nonuniform knot vector for the flexible modeling work. The results of this study are as follows. 1) By implementation surface modeler through applying representation scheme proposed to represent free-form surface explicity, the technical foundation to develop free-from surface modeling system using parametric method. 2) Besides the role to model geometric shape of a surface, geometric modeler is developed to model arbitrary geometric shape. By doing this, the availability of the modeling system is improved. Geometric modeler can be utilized application fields such as collision test of tool and fixture, and tool path generation for NC machine tool.