• Title/Summary/Keyword: Volumetric Error

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Computer integrated simulation of geometric features in 3 axis coordinate measuring machines

  • Pahk, Heui-Jae;Burdekin, M.;Peggs, G.
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 1991.10a
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    • pp.379-401
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    • 1991
  • A comprehensive computer software has been implemented in conjunction with the software for volumetric error generator, to assess simulation on specific measurement tasks. The simulation algorithms have been developed for major measurement tasks, such as step gauge, ring gauge, sphere gauge, and cylinder gauge simulations etc. Verification and practical applications of the developed module have shown its efficiency and validity.

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Quantitative Evaluation of Setup Error for Whole Body Stereotactic Radiosurgery by Image Registration Technique

  • Kim, Young-Seok;Yi, Byong-Yong;Kim, Jong-Hoon;Ahn, Seung-Do;Lee, Sang-wook;Im, Ki-Chun;Park, Eun-Kyung
    • Proceedings of the Korean Society of Medical Physics Conference
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    • 2002.09a
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    • pp.103-105
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    • 2002
  • Whole body stereotactic radiosurgery (WBSRS) technique is believed to be useful for the metastatic lesions as well as relatively small primary tumors in the trunk. Unlike stereotactic radiosurgery to intracranial lesion, inherent limitation on immobilization of whole body makes it difficult to achieve the reliable setup reproducibility. For this reason, it is essential to develop an objective and quantitative method of evaluating setup error for WBSRS. An evaluation technique using image registration has been developed for this purpose. Point pair image registrations with WBSRS frame coordinates were performed between two sets of CT images acquired before each treatment. Positional displacements could be determined by means of volumetric planning target volume (PTV) comparison between the reference and the registered image sets. Twenty eight sets of CT images from 19 WBSRS patients treated in Asan Medical Center have been analyzed by this method for determination of setup random error of each treatment. It is objective and clinically useful to analyze setup error quantitatively by image registration technique with WBSRS frame coordinates.

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The Least-Squares Meshfree Method for Linear Elasticity (최소 제곱 무요소법을 이용한 선형 탄성 변형 해석)

  • Kwon, Kie-Chan;Park, Sang-Hoon;Youn, Sung-Kie
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.11
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    • pp.2312-2321
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    • 2002
  • The first-order least-squares meshfree method for linear elasticity is presented. The conventional and the compatibility-imposed least-squares formulations are studied on the convergence behavior of the solution and the robustness to integration error. Since the least-squares formulation is a type of mixed formulation and induces positive-definite system matrix, by using shape functions of same order for both primal and dual variables, higher rate of convergence is obtained for dual variables than Galerkin formulation. Numerical examples also show that the presented formulations do not exhibit any volumetric locking for the incompressible materials.

Developement of Soil Moisture Meter using Capacitance Probe (정전용량 탐침을 이용한 토양수분 측정장치 개발)

  • Kim, Ki-Bok;Lee, Nam-Ho;Lee, Jong-Whan;Lee, Seung-Seok
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2001.10a
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    • pp.65-68
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    • 2001
  • This study was conducted to develop a soil moisture meter using capacitance probe. A parallel cylinder type capacitance probe (C-probe) was fabricated The 5 MHz of crystal oscillator was constructed to detect the capacitance change of the C-probe with moist soil. A third order polynomial regression model for volumetric water content having oscillation frequency changes at 5 MHz as independent variables presented the determination coefficient of 0.979 and root mean square error of $0.031\;cm^{3}cm^{3}$ for all soil samples. A prototype soil moisture meter consisting of the sample container, C-probe, oscillator, frequency counter and related signal procession units presented the correlation coefficient of 0.987 and the root mean square error of $0.032\;cm^{3}cm^{3}$ as compared with the oven drying method for unknown soil samples.

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가공정밀도 향상을 위한 공작기계 주축 열변형 오차보정에 관한 연구

  • 이찬호;박병규;이방희;김일규;김성청
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.05a
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    • pp.325-325
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    • 2004
  • 최근 UC 공작기계의 활용성 및 산업전반에 차지하는 중요성이 날로 증가하고, If기술을 접목한 네트워크 솔루션의 비약적인 발달에 힘입어 대부분의 공정들이 자동화됨에 따라 최종 부품의 가공정밀도는 전적으로 CNC 공작기계에 의존한다고 할 수 있다. 그러나 공작기계 각 구성 부품들의 가공오차와 조립 시 발생하는 기하학적 오차, 장시간 사용으로 인한 마모, 구조물의 온도 상승에 따른 열팽창 등으로 인하여 공구와 공작물간에 상대적인 공칭거리와 실제로 운동하는 거리와의 차이가 발생한다.(중략)

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Geometric Accuracy Measurement of Machined Surface Using the OMM (On the Machine Measurement) System

  • Kim, Sun-Ho;Lee, Seung-Woo;Kim, Dong-Hoon;Lee, An-Sung;Lim, Sun-Jong;Park, Kyoung-Taik
    • International Journal of Precision Engineering and Manufacturing
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    • v.4 no.4
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    • pp.57-63
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    • 2003
  • Machining information such as form accuracy and surface roughness is an important factor for manufacturing precise parts. To this regard, OMM (On the Machine Measurement) has been researched for last several decades to alternate CMM (Coordinate Measurement Machine) process. In this research, the OMM system with a laser displacement sensor was developed for measuring form accuracy and surface roughness of the machined workpiece on the machine tool. The surface roughness was estimated comparing the sensory signal with the reference data measured from master specimen. Also, form accuracy was determined from the moving averaged raw data. In addition, the geometric error map constructed beforehand using the geometric errors of the machine tool was used to compensate the obtained form accuracy. The overall performance was compared with CMM result, and verified the feasibility of the measurement system.

Enhanced Reconstruction of Heavy Occluded Objects Using Estimation of Variance in Volumetric Integral Imaging (VII) (Volumetric 집적영상에서 분산 추정을 이용한 심하게 은폐된 물체의 향상된 복원)

  • Hwang, Yong-Seok;Kim, Eun-Soo
    • Korean Journal of Optics and Photonics
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    • v.19 no.6
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    • pp.389-393
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    • 2008
  • Enhanced reconstruction of heavy occluded objects was represented using estimation of variance in computational integral imaging. The system is analyzed to extract information of enhanced reconstruction from an elemental images set. To obtain elemental images with enhanced resolution, low focus error, and large depth of focus, synthetic aperture integral imaging (SAII) utilizing a digital camera has been adopted. The focused areas of the reconstructed image are varied with the distance of the reconstruction plane. When an occluded object is occluded heavily, an occluded object can not be reconstructed by removing the occluding object. To obtain reconstruction of the occluded object by remedying the effect of heavy occlusion, the statistical technique has been adopted.

Automatic prostate segmentation method on dynamic MR images using non-rigid registration and subtraction method (동작 MR 영상에서 비강체 정합과 감산 기법을 이용한 자동 전립선 분할 기법)

  • Lee, Jeong-Jin;Lee, Ho;Kim, Jeong-Kon;Lee, Chang-Kyung;Shin, Yeong-Gil;Lee, Yoon-Chul;Lee, Min-Sun
    • Journal of Korea Multimedia Society
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    • v.14 no.3
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    • pp.348-355
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    • 2011
  • In this paper, we propose an automatic prostate segmentation method from dynamic magnetic resonance (MR) images. Our method detects contrast-enhanced images among the dynamic MR images using an average intensity analysis. Then, the candidate regions of prostate are detected by the B-spline non-rigid registration and subtraction between the pre-contrast and contrast-enhanced MR images. Finally, the prostate is segmented by performing a dilation operation outward, and sequential shape propagation inward. Our method was validated by ten data sets and the results were compared with the manually segmented results. The average volumetric overlap error was 6.8%, and average absolute volumetric measurement error was 2.5%. Our method could be used for the computer-aided prostate diagnosis, which requires an accurate prostate segmentation.

Evaluation of the Utility of a Volumetric Modulated Arc Therapy Specific Patient Quality Assurance using Software-based Quality Assurance System (소프트웨어 기반 정도관리 시스템을 이용한 부피세기조절회전치료 환자 별 정도관리의 유용성 평가)

  • Kang, Dong-Jin;Jung, Jae-Yong;Shin, Young-Joo;Min, Jung-Whan;Kim, Yon-Lae;Kwon, Kyung-Tae
    • Journal of radiological science and technology
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    • v.41 no.1
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    • pp.39-45
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    • 2018
  • The purpose of this study is to evaluate the usefulness of a software-based quality assurance system based on Volumetric Modulated Arc Therapy treatment plan. Evaluate treatment plan through the D VH analysis, PTV mean dose ($D_{mean}$) and PTV 95% dose($D_{95}$) compare the MFX based on original treatment plan, Average error rate was $0.9{\pm}0.6%$, $1.0{\pm}0.8%$, respectively. Measuring point dose using phantom and ion chamber, the average error rate between the ionization chamber and MFX was $0.9{\pm}0.7%$, $1.1{\pm}0.7%$ (high dose region), $1.1{\pm}0.9%$, $1.2{\pm}0.7%$ (low dose region). The average gamma though of MFX and $Delta^{4PT}$ is $98.7{\pm}1.2%$, $98.4{\pm}.3%$, respectively. Through this study, A software based QA system that simplifies hardware based QA procedures that involve a lot of time and effort. It can be used as a simple and useful tool in clinical practice.

Volumetric Interferometry Using Spherical Wave Interference for Three-dimensional Coordinate Metrology

  • Rhee, Hyug-Gyo;Chu, Ji-Young;Kim, Seung-Woo
    • Journal of the Optical Society of Korea
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    • v.5 no.4
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    • pp.140-145
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    • 2001
  • We present a new method of volumetric interferometer, which is intended to measure the three-dimensional coordinates of a moving object in a simultaneous way with a single optical setup. The method is based on the principles of phase-measuring interferometry with phase shifting. Two diffraction point sources, which are made of the polished ends of single-mode optical fibers are embedded on the object. Two spherical wavefronts emanate from the diffraction point sources and interfere with each other within the measurement volume. One wavefront is phase-shifted by elongating the corresponding fiber using a PZT extender. A CCD array sensor fixed at the stationary measurement station detects the resulting interference field. The measured phases are then related to the three-dimensional location of the object with a set of non-liner equations of Euclidean distance, from which the complete set of three-dimensional spatial coordinates of the object is determined through rigorous numerical computation based upon the least square error minimization.