• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.501-506
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• 1988

This paper describes an experimental system for automatic robot programming, The SNU-ARPS (Seoul National University Automatic Robot Programming System). The SNU-ARPS generates executable robot programs for pick and place operation and some simple mechanical assembly tasks by menudriven dialog. It is intended to enable the user to concentrate on the overall operation sequence instead of the knowledge regarding the details of robot languages. To convert task specifications into manipulator motions, the SNU-ARPS uses an internal representation of the world. This representation initially consists of geometric database from CAD system and is updated at each operation step to reflect the state changes of the world.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1990.10a
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• pp.40-46
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• 1990

This paper introduces a geometric modelling system adopted in a newly developed preprocessor for finite element analysis of three dimensional structures. The formulation is characterized by hierarchical construction of structural model which consists of control points, curves, surfaces and solids. Various surface and solid modeling schemes based on blending functions and boundary representation are systematized for finite element mesh generation. The modeling system is integrated with model synthesis and operations which facilitate modelling of complex structures.

• International Journal of Precision Engineering and Manufacturing
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• v.2 no.2
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• pp.73-80
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• 2001

The objective of this research is to develop a measurement error model for sculptured surface in On-Machine Measurement(OMM) process based on a closed-loop configuration. The geometric error model of each axis of a vertical CNC machining center is derived using a 4$\times$4 homogeneous transformation matrix. The ideal locations of a touch-type probe for the sculptured surface measurement are calculated from the parametric surface representation and X-, Y- directional geometric errors of the machine. Also the actual coordinates of the probe are calculated by considering the pre-travel variation of a probe and Z-directional geometric errors. Then, the step-by-sep measurement error analysis method is suggested based on a closed-loop configuration of the machining center including workpiece and probe errors. The simulation study shows the simplicity and effectiveness of the proposed error modeling strategy.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.10
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• pp.172-181
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• 1999

The objective of this research is to develop a measurement error model for sculptured surfaces in On-Machine Measurement (OMM) process based on a closed-loop configuration. The geometric error model of each axis of a vertical CNC Machining center is derived using a 4${\times}$4 homogeneous transformation matrix. The ideal locations of a touch-type probe for the scupltured surface measurement are calculated from the parametric surface representation and X-, Y- directional geometric errors of the machine. Also, the actual coordinates of the probe are calculated by considering the pre-travel variation of a probe and Z-directional geometric errors. Then, the step-by-step measurement error analysis method is suggested based on a closed-loop configuration of the machining center including workpiece and probe errors. The simulation study shows the simplicity and effectiveness of the proposed error modeling strategy.

• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.833-835
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• 2002

In this paper, we propose multi-resolutional representation of B-rep solid models using the selective Boolean operations on non-manifold geometric models. Since the union and subtraction operations of the selective Boolean operations are commutative, the integrity of the model is guaranteed for reordering design features. A multi-resolution representation is established using a non-manifold merged set model and a feature modeling tree reordered according to some criterion of level of detail (LOD). Then, a solid model for a specified LOD can be extracted from this multi-resolution model using the selective Boolean operations.

• Journal of applied mathematics & informatics
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• v.11 no.1_2
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• pp.1-57
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• 2003

Vector fields in three-space admit bundles of internal variables such as a Heisenberg algebra bundle. Information transmission along field lines of vector fields is described by a wave linked to the Schrodinger representation in the realm of time-frequency analysis. The preservation of local information causes geometric optics and a quantization scheme. A natural circle bundle models quantum information visualized by holographic methods. Features of this setting are applied to magnetic resonance imaging.

• Journal of the Chungcheong Mathematical Society
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• v.23 no.3
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• pp.495-510
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• 2010

An Einstein's connection which takes the form (2.23) is called a $^*g$-ME-connection and the corresponding vector is called a $^*g$-ME-vector. The $^*g$-ME-manifold is a generalized n-dimensional Riemannian manifold $X_n$ on which the differential geometric structure is imposed by the unified field tensor $^*g^{{\lambda}{\nu}}$, satisfying certain conditions, through the $^*g$-ME-connection and we denote it by $^*g-MEX_n$. The purpose of this paper is to derive a general representation and a special representation of the $^*g$-ME-vector in $^*g-MEX_n$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.803-804
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• 2011

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.429-436
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• 2003

A new linkage framework between elastic shell element with finite rotation and computar-aided geometric design (CAGD) (or surface is developed in the present study. The framework of shell finite element is based on the generalized curved two-parametric coordinate system. To represent free-form surface, cubic B-spline tensor-product functions are used. Thus the present finite element can be directly linked into the geometric modeling produced by surface generation tool in CAD software. The efficiency and accuracy of the Previously developed linear elements hold for the nonlinear element with finite rotations. To handle the finite rotation behavior of shells, exponential mapping in the SO(3) group is employed to allow the large incremental step size. The integrated frameworks of shell geometric design and nonlinear computational analysis can serve as an efficient tool in shape and topological design of surfaces with large deformations.