• 한국컴퓨터그래픽스학회논문지
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• 제6권4호
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• pp.29-34
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• 2000

이 논문에서는 평행이동곡면 (surface of extrusion) 과 임의의 자유곡면 사이의 교차곡선의 구조를 분석하고 이를 계산하는 방법에 대해 설명한다. 평행이동곡면의 이동방향에 대하여 다른 곡면의 윤곽곡선 (silhouette curve) 을 구하고, 이를 평행이동곡면의 기준곡선과 교차시킴으로써 교차곡선의 구조를 분석한다. 또한, 교차곡선이 존재하는 범위와 특이점을 구함으로써 교차곡선 전체를 안정적이고 효율적으로 계산하는 알고리즘을 제시한다.

• 한국정보처리학회논문지
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• 제7권4호
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• pp.1271-1278
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• 2000

A general curve and surface is a basic method to generate Free-form object using the fundamental properties of blending function. In typical method, there is an overhead of calculating to present Free-form object with the line segments and interpolation algorithm, In this paper, for resolving this problem efficiently, it will propose the flexible Free-form curves/surfaces using Ball curve shape-preserving property. This method includes Geometric Continuity that is needed to design Free-form Surface of high degree consisted with many curves. Also, when lots of data are reduced using Geometric Property of Free-form curves, the shape-preserving property of resulting object can be maintained, then it can represent any Free-form object with less calculating .

• International Journal of Precision Engineering and Manufacturing
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• 제9권2호
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• pp.84-92
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• 2008

Free-form shapes which were once considered as an aesthetic feature are now an important functional requirement. CNC industries are looking for a compact solution for reproducing free-form shapes as conventional interpolation models are inadequate, The parametric curve interpolator developed in the last decade has clearly emerged as favorite among its contemporaries in recent years, At present intense research has been done on parametric curve interpolators and interesting developments are reported. Out of the various parametric representations for curves and surfaces, NURBS has been standardized and widely used in free-form shape design. This paper presents a review of various methods of parametric interpolation for NURBS and discusses the salient features, problems and solutions. Recent approaches on variable feedrate interpolation, parameter compensation are also reviewed and research trends are addressed finally.

• 한국정밀공학회지
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• 제22권8호
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• pp.76-83
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• 2005

In this study a general method for computing offsets of free form curves is presented. In the method arbitrary free form curve is approximated with point series considering required tolerance. The point series are offset precisely using the normal vectors computed at each point and loop removal is carried out by the newly suggested algorithm. The resulting offset points are transformed to lines and arcs using the biarc approximation method. Tangent vectors for approximation of discrete points data are calculated by traditional local interpolation scheme. In order to show the validity and generality of the proposed method , various of offsettings are carried our for the base curves with complex shapes.

• 한국정밀공학회지
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• 제33권9호
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• pp.745-751
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• 2016

This paper presents the acceleration and deceleration control of free-form surfaces. A rapid variation of acceleration (or Deceleration) drives the system into a machine shock, resulting in the inaccuracy of the path control of the NURBS curve. The pattern of acceleration control can be established using the curvature of the NURBS curve. The curvature can be easily calculated from the first and second derivative of the NURBS curve used in Taylor's expansion for NURBS interpolation. However, the derivatives are not used in the recursive method for NURBS interpolation. Hence, we attempted the difference-derivatives for calculating the NURBS curvature. Both, Taylor's expansion and the recursive method, are used jointly for controlling the acceleration in the same interpolation algorithm.

• 수산해양기술연구
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• 제39권4호
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• pp.298-304
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• 2003

In this paper a free-form hull design program and performance prediction program for planing boat is introduced. This program enables the designer to do complex geometric hull shape design on a personal computer and accurately to predict power requirements for a given loading and velocity. For a free form design, Bezier curve model is adopted as a basic representation tool of curves and surfaces, and this program has versatile functions to do fairing jobs with a convenient graphical user interface. After creating a hull form the geometric data is provided in a manner compatible with a variety of analysis tools including 'Motion Analysis(by Zarnick)' for prediction of motion characteristics in regular waves, 'Running Attitude (by Savitsky)' for prediction of the running attitude and required power.

• 한국정밀공학회지
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• 제16권4호통권97호
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• pp.129-137
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• 1999

A parametric curve interpolator has been proposed for machining curves instead of a linear interpolator in which curves are approximated by a set of line segment. The parametric curve interpolator is superior to linear interpolator in machining time and contour error and generate exact position commands directly from curve equations. In this paper, a new toolpath generation method is proposed based on the parametric curve interpolator. This method retains all the benefits of parametric curve interpolator and can bound the scallop height within a specified value. By interpolating curves and surfaces directly from the mathematical equations, the amount of data from CAD/CAM system to CNC controller can be significantly reduced. The proposed method was implemented on a CNC controller and was confirmed to give a better result than the other existing method.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.33-34
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• 2018

Currently, free-form building has been increased worldwide. However, as a finishing material of free-form building, the production of free-form concrete panels(FCPs) spends lots of cost and efforts since it is difficult to reuse the FCP formwork and lots of workers are needed to make free-form curve. In addition, the technology to produce the FCP economically and easily is insufficient. Therefore, the objective of this study is a basic study regarding production management for developing free-form concrete panels. To achieve the objective, the property of FCP and condition for effective production management and production process are analyzed. The results of this study can utilize to develop the algorithm for FCP production management.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.166-167
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• 2016

Unlike the past, supported by the development of digital technologies, free-form buildings are frequently designed with creative thoughts of architectural designers. However, there are some difficulties preventing successfully completion of projects, like reduced productivity and increased construction duration and cost upon the process of producing and installing concrete panels for free-form structures. In particular, there are active studies on the CNC machine for production of free-form concrete panels. Yet, it is difficult to effectively and easily come up with information on production and installation of free-form, curve-surfaced panels which are difficult to be mathematically defined. This requires a lot of manpower and time to implement the curved surfaces of free-form buildings as intended by architects. Accordingly, it needs a model that can effectively create production-installation data of free-form concrete panels for successful free-form building projects. Thus, the purpose of the study is to suggest data estimation model of production-installation using mathematical algorithm in free-form concrete panels. The study results will realize effective production and installation of free-form concrete members, allowing improved productivity of projects, reduced cost and shortened construction duration.

• 한국지능시스템학회논문지
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• 제8권5호
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• pp.45-50
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• 1998

본 연구에서는 입출력 데이터로부터 비선형 다변수 모델을 자동 인식할 수 있는 적응형 Spline모델링(ASMOD : Adaptive Spline Modeling of Observation Data)과 혼합 곡선 근사법(Hybrid curve approximation)을 이용한 3차원 자유 형상 설계방법을 제안하고, 초기 선형 설계 단계에서 횡단면적 곡선(SAC : Sectional Area Curve) 생성 예를 통해 그 응용 가능성을 검토하였다. 즉 실적선의 SAC를 Bspline 근사법(Fitting methdo)과 유전자 알고리즘(Genetic Algorithm)에 의해 정의하여, 조정점(Control points)에 대한 데이터베이스를 구축한다. 구축된 데이터베이스-주요치수와 이들 조정점관의 관계-를 학습 데이터로 하여 ASMOD를 학습시킨후 , SAC결정을 위한 ASMOD 모델링을 구축한다. 다른 선형 특성 곡선들-design waterline curve, bottom tangent line, center profile line-에 대해서도 동일하게 적용하여 ASMOD를 모델링할 수 있으며, 이들 선형 특성 곡선들을 결합하여 초기 선형을 생성한다.