• 제목/요약/키워드: spline

검색결과 1,106건 처리시간 0.033초

최적 비정규 리샘플링 알고리즘 (Optimal Non-Uniform Resampling Algorithm)

  • 신건식;이학무;강문기
    • 대한전자공학회논문지SP
    • /
    • 제39권2호
    • /
    • pp.50-55
    • /
    • 2002
  • 영상 리샘플링의 전형적인 방법은 원래의 디지털 영상을 연속 모델에 맞춘 뒤 원하는 샘플링율로 다시 샘플링하는 접근방식에 기초한다. B-스플라인 함수는 다른 함수에 비해 오실레이션이 적어 연속 모델에 주로 사용되어 온 함수이다. 이 논문의 주 목표는 비정규 최적 리샘플링 알고리즘의 유도이다. 이 알고리즘을 유도하기 위해서 세단계의 근사화가 필요하다: 1) 역행렬 연산을 통한 B-스플라인 계수 구하기, 2) 직교 투사 이론에 의해 유도된 최적 리샘플링 알고리즘을 이용하여 변환된 B-스플라인 계수 구하기, 3) 간접B-스플라인 변환을 통해 결과를 다시 신호 영역으로 바꾸기. 이러한 방법을 통해 정규 리샘플링에서 그 우수성이 입증된 B-spline을 비정규 리샘플링에서도 이용할 수 있으며 실험 결과를 통해 성능의 우수성을 확인할 수 있다.

B-Spline 고차 경계요소법을 이용한 3차원 수중익의 날개 끝 와류유동 수치해석 (Numerical Analysis of Tip Vortex Flow of Three-dimensional Hydrofoil using B-Spline Higher-order Boundary Element Method)

  • 김지혜;안병권;김건도;이창섭
    • 한국해양공학회지
    • /
    • 제31권3호
    • /
    • pp.189-195
    • /
    • 2017
  • A three-dimensional higher order boundary element method based on the B-spline is presented. The method accurately models piecewise continuous bodies and induced velocity potentials using B-spline tensor product representations, and it is capable of obtaining accurate pointwise values for the potential and its derivatives, especially in the trailing edge and tip region of the lift generating body, which may be difficult or impossible to evaluate with constant panel methods. In addition, we implement a wake roll-up and examine the tip vortex formation in the near wake region. The results are compared with existing numerical results and the results of experiments performed out at the cavitation tunnel of Chungnam National University.

B 스플라인 고차 패널법을 적용한 부유체 운동해석 (Application of the B-Spline Based High Order Panel Method to the Floating Body Dynamics)

  • 안병권;유재문;이현엽;이창섭
    • 한국해양공학회지
    • /
    • 제22권5호
    • /
    • pp.25-30
    • /
    • 2008
  • A B-spline based high order panel method was developed for the motion of bodies in an ideal fluid, either of infinite extent or with a free boundarysurface. In this method, both the geometry and the potential are represented by the B-spline, which guarantees more accurate results than most potential based low order methods. In the present work, we applied this B-spline based high order method to the radiation problem of floating bodies. The boundary condition on the free surface was satisfied by adopting a Kelvin-type Green function and irregular frequencies were removed by placing additional control points on the free surface surrounding the body. The numerical results were validated by comparison with existing numerical and experimental results.

CAD 와의 연동을 고려한 T-스플라인 유한요소해석 (T-spline Finite Element Method Integrated with CAD)

  • 엄태경;윤성기
    • 대한기계학회:학술대회논문집
    • /
    • 대한기계학회 2007년도 춘계학술대회A
    • /
    • pp.672-677
    • /
    • 2007
  • Recently, the new finite element method which uses NURBS as shape functions was proposed. It is very promising because it can directly use CAD data to describe geometry and discretize problem domain. In this case, CAE models are not approximated but represent exact geometry. So, it can contribute to more accurate results. In addition, it can greatly reduce CAE costs in that simulation models don't have to be made up independently. But in spite of these advantages, the method using NURBS have also some disadvantages. NURBS surface cannot be refined locally. T-splines are recently developed surface modeling technique. A T-spline surface is a NURBS surface with T-junctions and is defined by a control grid called T-mesh. The T-junctions enable T-spline surfaces to be refined locally. That is, it is possible to add a single control point to a T-spline control grid without propagating an entire row or column of control points and without altering the surface. In this research, the finite element analysis using T-splines is studied. In this analysis, CAD data are used directly for engineering analysis. Some problems with complex geometry are solved. And the results will be compared with ones of conventional FEM.

  • PDF

벌점 스플라인 회귀모형에서의 이상치 탐지방법 (An Outlier Detection Method in Penalized Spline Regression Models)

  • 서한손;송지은;윤민
    • 응용통계연구
    • /
    • 제26권4호
    • /
    • pp.687-696
    • /
    • 2013
  • 이상치가 존재하는 경우 모형 적합의 결과가 왜곡될 수 있기 때문에 이상치 탐색은 데이터분석에 있어서 매우 중요하다. 이상치 탐지 방법은 많은 학자들에 의해 연구되어 왔다. 본 논문에서는 Hadi와 Simonoff (1993)가 제안한 직접적 이상치 탐지 방법을 벌점 스플라인 회귀모형에 적용하여 이상치를 탐지하는 과정을 제안하며 모의실험과 실제 데이터에 적용을 통하여 스플라인 회귀모형, 강건 벌점 스플라인 회귀모형과 효율성을 비교한다.

Modeling Implied Volatility Surfaces Using Two-dimensional Cubic Spline with Estimated Grid Points

  • Yang, Seung-Ho;Lee, Jae-wook;Han, Gyu-Sik
    • Industrial Engineering and Management Systems
    • /
    • 제9권4호
    • /
    • pp.323-338
    • /
    • 2010
  • In this paper, we introduce the implied volatility from Black-Scholes model and suggest a model for constructing implied volatility surfaces by using the two-dimensional cubic (bi-cubic) spline. In order to utilize a spline method, we acquire grid (knot) points. To this end, we first extract implied volatility curves weighted by trading contracts from market option data and calculate grid points from the extracted curves. At this time, we consider several conditions to avoid arbitrage opportunity. Then, we establish an implied volatility surface, making use of the two-dimensional cubic spline method with previously estimated grid points. The method is shown to satisfy several properties of the implied volatility surface (smile, skew, and flattening) as well as avoid the arbitrage opportunity caused by simple match with market data. To show the merits of our proposed method, we conduct simulations on market data of S&P500 index European options with reasonable and acceptable results.

히스토그램 및 Spline 보간법을 이용한 Salt & Pepper 잡음 제거 (Salt & Pepper Noise Removal Using Histogram and Spline Interpolation)

  • 고유학;권세익;김남호
    • 한국정보통신학회:학술대회논문집
    • /
    • 한국정보통신학회 2017년도 추계학술대회
    • /
    • pp.691-693
    • /
    • 2017
  • 영상처리는 현대사회가 고도의 디지털 정보화 시대로 발전함에 따라 응용분야가 점차 확대되고, 중요한 분야로 이용되고 있다. 영상 데이터는 영상을 전송하는 과정에서 여러 원인에 의해 열화가 발생하며, 대표적으로는 salt & Pepper 잡음이 있다. salt & pepper 잡음을 제거하기 위한 기존의 방법들은 잡음 제거 특성이 다소 미흡하다. 따라서 본 논문에서는 salt & pepper 잡음에 훼손된 영상의 히스토그램을 이용한 가중치 필터와 국부 마스크의 방향에 따른 spline 보간법을 적용하여 처리하는 알고리즘을 제안하였다.

  • PDF

A Proprietary Model of Continuously Variable Transmission System using Spline

  • Gu, Sien Dong
    • International journal of advanced smart convergence
    • /
    • 제11권1호
    • /
    • pp.87-93
    • /
    • 2022
  • In each country, efforts are being made to replace engine-driven cars and motorcycles using fossil fuels with electric drive. Electrically driven vehicles have the advantage of no harmful gas or environmental pollution and low noise. In the motorcycle market, China accounts for more than 95% of the world, and the electric motorcycle market is being revitalized due to the strengthening of regulations. Japan is actively preparing to include electric motorcycles in ISO 26262, forming a TF team centered on electric motorcycle producers. Therefore, it is necessary to respond to standardization targeting China and Japan in Korea. In this study, we propose a proprietary transmission model that can be applied to small electric vehicles that can be operated in hilly domestic terrain. The proposed continuously variable transmission model is a continuously variable transmission system which moves the pin between the basic disk and the rotary disk using a spline to perform shifting. The proposed continuously variable transmission model is used in the pulley configuration by connecting the linear type spline and the inclined spline with the central axis of the basic disk and the rotational disk, respectively. In addition, it can be divided into two types according to the application of the auxiliary disk, and the production drawing is completed for the practical use of the model.

수정 B-spline 근사를 통한 역공학 적용에 관한 연구 (A Study on Application of Reverse Engineering using Modified B-spline approximation)

  • 황종대;정종윤;정윤교
    • 한국산업경영시스템학회:학술대회논문집
    • /
    • 한국산업경영시스템학회 2002년도 춘계학술대회
    • /
    • pp.473-478
    • /
    • 2002
  • Reverse Engineering is to find CAD model through measured data of a physical model which is not available in CAD model. The measured data are obtained from measuring with Coordinate Measuring Machine or Laser Scanner This paper introduces efficient methods of reconstruction through the application of the Reverse Engineering using Modified B-spline approximation.

  • PDF