• 한국정밀공학회지
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• 제18권9호
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• pp.61-70
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• 2001

This paper introduces a new digitization method with sensor fusion for shape measurement in reverse engineering. Digitization can be classified into contact and non-contact type according to the measurement devices. Important thing in digitization is speed and accuracy. The former is excellent in speed and the latter is good for accuracy. Sensor fusion in digitization intends to incorporate the merits of both types so that the system can be automatized. Firstly, non-contact sensor with vision system acquires coarse 3D point data rapidly. This process is needed to identify and loco]ice the object located at unknown position on the table. Secondly, accurate 3D point data can be automatically obtained using scanning probe based on the previously measured coarse 3D point data. In the research, a great number of measuring points of equi-distance were instructed along the line acquired by the vision system. Finally, the digitized 3D point data are approximated to the rational B-spline surface equation, and the free-formed surface information can be transferred to a commercial CAD/CAM system via IGES translation in order to machine the modeled geometric shape.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1997년도 추계 학술대회논문집
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• pp.66-72
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• 1997

Circular-to-rectangular transition ducts are used as exhaust components of high performance fighter aircraft with vectored thrust nozzles. Three-dimensional incompressible Navier-Stokes solver is used to analyze the transition duct. Cross sections of transition duct are defined by superelliptic equation. The grid system is generated by Non-Uniform Rational B-Spline, after generating surface grid by blending the cross sections. Good agreement between the results of the computational simulation and the experimental data is observed.

• 대한기계학회논문집A
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• 제31권1호
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• pp.105-112
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• 2007

The linkage framework of geometric modeling based on NURBS(Non-Uniform Rational B-Spline) surface and shell finite analysis is developed in the present study. For this purpose, geometrically exact shell finite element is implemented. NURBS technology is employed to obtain the exact geometric quantities for the analysis. Especially, because NURBS is the most powerful and wide-spread method to represent general surfaces in the field of computer graphics and CAD(Computer Aided Design) industry, the direct computation of surface geometric quantities from the NURBS surface equation without approximation shows great potential for the integration between geometrically exact shell finite element and geometric modeling in the CAD systems. Some numerical examples are given to verify the performance and accuracy of the developed linkage framework. In additions, trimmed surfaces with some cutouts are considered for more practical applications.

• 대한조선학회논문집
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• 제36권2호
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• pp.121-134
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• 1999

본 논문에서는 유체 정역학적 계산, 용적 계산, 비손상 및 손상시 복원성 그리고, 선형 변환을 수행할 수 있는 객체 지향적 선박계산 전산프로그램을 개발하였다. 선박 계산을 위한 선형과 구획 형상을 NURBS(Non-Uniform Rational B-Spline) curve wire-frame model로 표현하고, 선형과 구획 단면 형상을 직접 3차원 평면과의 교차 계산을 통해 유체 정역학적 계산과 용적 계산을 수행하였다. 선박의 3차원 정역학적 평형 상태 방정식을 정식화하고, 순차적으로 선형화하여 힘과 모멘트 평형상태의 자세를 구하였다. 상용 선박 계산 프로그램의 결과와 비교하여, 개발 프로그램을 쉽고, 편리하게 사용할 수 있고, 계산의 정확도가 높음을 확인할 수 있었다.