• Title/Summary/Keyword: Interpolation accuracy

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A Study on the Determination of WGS84 Geoidal Height by the Interpolation Methods (보간방법에 의한 WGS84 지오이드고 결정에 관한 연구)

  • 강준묵;김홍진
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.13 no.2
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    • pp.237-244
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    • 1995
  • In this study, we made WGS84 geoidal height model from GPS measurements for bench marks and calculated geoidal height of B.Ms which were selected check points using the hi-linear, trend surface fitting and triangulation interpolation method. From these, the interpolation accuracy was studied. Also, we tried to study accuracy of height transformation by making up orthometric height with latitude and longitude on Bessel ellipsoid for bench marks which were calculated by applying transformation parameters that were got GPS measurements for precise primary control stations. As a result of this study, the WGS84 geoidal height and orthometric height could be determined as a deviation value of 20 cm.

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Identification of motion error sources in NC machine tools by a circular interpolation test (원호보간시험에 의한 수치제어 공작기계의 운동오차원인 진단에 관한 연구)

  • Hong, Seong-Wook;Shin, Young-Jae;Lee, Hu-Sang
    • Journal of the Korean Society for Precision Engineering
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    • v.10 no.2
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    • pp.126-137
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    • 1993
  • This paper presents an efficient method for the identification of motion error sources in NC machine tools by making use of the circular interpolation test, which is often used in estimating the motion accuracy of NC machine tools. Mathematical formulae are described for motion errors due to various kinds of error sources. Two identification formulae are proposed: one is based on the frequency analysis and the other is formulated with the weithted residual method. Motion error signal is classified into two patterns, mean errors(mean of CW and CCW test signals from mean errors). The sources of the mean errors are identified by using the frequency analysis technique and the sources of the deviation errors by the weighted residual formulaltion. A menu driven, user oriented, computer program is written to realize the full steps of the proposed identificationprocedure. Then, the identification method is applied to two NC machine tools.

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Ordinary Kriging of Daily Mean SST (Sea Surface Temperature) around South Korea and the Analysis of Interpolation Accuracy (정규크리깅을 이용한 우리나라 주변해역 일평균 해수면온도 격자지도화 및 내삽정확도 분석)

  • Ahn, Jihye;Lee, Yangwon
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.40 no.1
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    • pp.51-66
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    • 2022
  • SST (Sea Surface Temperature) is based on the atmosphere-ocean interaction, one of the most important mechanisms for the Earth system. Because it is a crucial oceanic and meteorological factor for understanding climate change, gap-free grid data at a specific spatial and temporal resolution is beneficial in SST studies. This paper examined the production of daily SST grid maps from 137 stations in 2020 through the ordinary kriging with variogram optimization and their accuracy assessment. The variogram optimization was achieved by WLS (Weighted Least Squares) method, and the blind tests for the interpolation accuracy assessment were conducted by an objective and spatially unbiased sampling scheme. The four-round blind tests showed a pretty high accuracy: a root mean square error between 0.995 and 1.035℃ and a correlation coefficient between 0.981 and 0.982. In terms of season, the accuracy in summer was a bit lower, presumably because of the abrupt change in SST affected by the typhoon. The accuracy was better in the far seas than in the near seas. West Sea showed better accuracy than East or South Sea. It is because the semi-enclosed sea in the near seas can have different physical characteristics. The seasonal and regional factors should be considered for accuracy improvement in future work, and the improved SST can be a member of the SST ensemble around South Korea.

A Study on The Error Analysis of Integration Operational Metrices by The Lagrange Second Order Interpolation Polvnomial (Lagrange 이차 보간 다항식을 이용한 적분연산 행렬의 오차 해석에 관한 연구)

  • Lee, Hae-Ki;Kim, Tai-Hoon
    • Proceedings of the KIEE Conference
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    • 2003.07e
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    • pp.55-57
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    • 2003
  • This paper presents a new method for finding the Block Pulse series coefficients and deriving the Block Pulse integration operational matrices which are necessary for the control fields using the Block Pulse functions. In this paper, the accuracy of the Block Pulse series coefficients derived by using the Lagrange second order interpolation polynomial is approved by the mathematical method.

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A Study on the Combined Use of Exact Dynamic Elements and Finite Elements (엄밀한 동적 요소와 유한 요소 통합 해석 방법에 관한 연구)

  • 홍성욱;조용주;김종선
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.2
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    • pp.141-149
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    • 2002
  • Although the finite element method has become an indispensible tool for the dynamic analysis of structures, difficulty remains to quantify the errors associated with discretization. To improve the modeling accuracy, this paper proposes a method to make a combined use of finite elements and exact dynamic elements. Exact interpolation functions for the Timoshenko beam element are derived using the exact dynamic element modeling (EDEM) and compared with interpolation functions of the finite element method (FEM). The exact interpolation functions are tested with the Laplace variable varied. A combined use of finite element method and exact interpolation functions is presented to gain more accurate mode shape functions. This paper also presents a combined use of finite elements and exact dynamic elements in design/reanalysis problems. Timoshenko flames with tapered sections are tested to demonstrate the design procedure with the proposed method. The numerical study shows that the combined use of finite element model and exact dynamic element model is very useful.

Kriging Dimension Reduction Method for Reliability Analysis in Spring Design (스프링 설계문제의 신뢰도 해석을 위한 크리깅 기반 차원감소법의 활용)

  • Gang, Jin-Hyuk;An, Da-Wn;Won, Jun-Ho;Choi, Joo-Ho
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2008.04a
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    • pp.422-427
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    • 2008
  • This study is to illustrate the usefulness of Kriging Dimension Reduction Method(KDRM), which is to construct probability distribution of response function in the presence of the physical uncertainty of input variables. DRM has recently received increased attention due to its sensitivity-free nature and efficiency that considerable accuracy is obtained with only a few number of analyses. However, the DRM has a number of drawbacks such as instability and inaccuracy for functions with increased nonlinearity. As a remedy, Kriging interpolation technique is incorporated which is known as more accurate for nonlinear functions. The KDRM is applied and compared with MCS methods in a compression coil spring design problem. The effectiveness and accuracy of this method is verified.

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Multimodal Medical Image Registration based on Image Sub-division and Bi-linear Transformation Interpolation (영상의 영역 분할과 이중선형 보간행렬을 이용한 멀티모달 의료 영상의 정합)

  • Kim, Yang-Wook;Park, Jun
    • Journal of Biomedical Engineering Research
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    • v.30 no.1
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    • pp.34-40
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    • 2009
  • Transforms including translation and rotation are required for registering two or more images. In medical applications, different registration methods have been applied depending on the structures: for rigid bodies such as bone structures, affine transformation was widely used. In most previous research, a single transform was used for registering the whole images, which resulted in low registration accuracy especially when the degree of deformation was high between two images. In this paper, a novel registration method is introduced which is based image sub-division and bilinear interpolation of transformations. The proposed method enhanced the registration accuracy by 40% comparing with Trimmed ICP for registering color and MRI images.

Half-pel Accuracy Motion Estimation Algorithm using Selective Interpolation in the Wavelet Domain (웨이블릿 영역에서의 선택적인 보간에 의한 반화소 단위 움직임 추정)

  • 이경환;정영훈;황희철
    • Journal of Korea Multimedia Society
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    • v.6 no.1
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    • pp.40-47
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    • 2003
  • In this paper, we propose a new method for reducing the computational overhead of fine-to-coarse multi-resolution motion estimation (MRME) at the finest resolution level by searching for the region to consider motion vectors of the coarsest resolution subband. At this time, if half-pel accuracy motion estimation (HPAME) is used in the baseband where influence a lot of effect to the reconstructed image, we can have the motion vector exactly But, this method causes to higher computational overhead. So we suggest the method to the computational overhead by using selective interpolation. Experimental results show that the proposed algorithm gives better results than the traditional algorithms from image quality.

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RICHARDSON EXTRAPOLATION AND DEFECT CORRECTION OF MIXED FINITE ELEMENT METHODS FOR ELLIPTIC OPTIMAL CONTROL PROBLEMS

  • Chen, Yanping;Huang, Yunqing;Hou, Tianliang
    • Journal of the Korean Mathematical Society
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    • v.49 no.3
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    • pp.549-569
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    • 2012
  • In this paper asymptotic error expansions for mixed finite element approximations to a class of second order elliptic optimal control problems are derived under rectangular meshes, and the Richardson extrapolation of two different schemes and interpolation defect correction can be applied to increase the accuracy of the approximations. As a by-product, we illustrate that all the approximations of higher accuracy can be used to form a class of a posteriori error estimators of the mixed finite element method for optimal control problems.

A study on the improvement of cutting precision of CNC system using $H_{\infty}$ 2-degree-of-freedom controller ($H_{\infty}$ 2 자유도 제어기를 이용한 CNC 시스템의 가공 정밀도 향상에 관한 연구)

  • 최성규;최병욱;현용탁;강성귀;권욱현
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.1040-1043
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    • 1996
  • The accuracy of the servo control in CNC system has a great influence on the duality of machine product. Tracking performance of the servo control is deteriorated mainly by the time delay of the servo system and the inertia of the work table or bed. Contouring errors occur in every interpolation steps by the effect of the tracking performance. In this paper, $H_{\infty}$ two-degree-of-freedom(TDF) controller is designed for improvement to improve the tracking performance. The designed controller is applied 3-axis machining center model and the cutting accuracy is simulated in case of corner cutting, circular and involute interpolation. Simulation results show that $H_{\infty}$ TDF controller designed in this paper has a good effect to improve tracking performance in CNC system.

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