• Title/Summary/Keyword: 윤곽 오차

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Design of the Fuzzy Logic Cross-Coupled Controller using a New Contouring Modeling (새로운 윤곽 모델링에 의한 퍼지논리형 상호결합제어기 설계)

  • Kim, Jin-Hwan;Lee, Je-Hie;Huh, Uk-Youl
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.37 no.1
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    • pp.10-18
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    • 2000
  • This paper proposes a fuzzy logic cross-coupled controller using a new contouring modeling for a two-axis servo system. The general decoupled control approach may result in degraded contouring performance due to such factors as mismatch of axial dynamics and axial loop gains. In practice, such systems contain many uncertainties. The cross-coupled controller utilizes all axis position error information simultaneously to produce accurate contours. However, the conventional cross-coupled controllers cannot overcome friction, backlash, and parameter variations. Also since, it is difficult to obtain an accurate mathematical model of multi-axis system, here we investigate a fuzzy logic cross-coupled controller of servo system. In addition, new contouring error vector computation method is presented. The experimental results are presented to illustrate the performance of the proposed algorithm.

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Differences in Target Volume Delineation Using Typical Radiosurgery Planning System (각각의 방사선수술 치료계획시스템에 따른 동일 병변의 체적 차이 비교)

  • Han, Su Chul;Lee, Dong Joon
    • Progress in Medical Physics
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    • v.24 no.4
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    • pp.265-270
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    • 2013
  • Correct target volume delineation is an important part of radiosurgery treatment planning process. We designed head phantom and performed target delineation to evaluate the volume differences due to radiosurgery treatment planning systems and image acquisition system, CT/MR. Delineated mean target volume from CT scan images was $2.23{\pm}0.08cm^3$ on BrainSCAN (NOVALS), $2.13{\pm}0.07cm^3$ on Leksell gamma plan (Gamma Knife) and $2.24{\pm}0.10cm^3$ on Multi plan (Cyber Knife). For MR images, $2.08{\pm}0.06cm^3$ on BrainSCAN, $1.94{\pm}0.05cm^3$ on Leksell gamma plan and $2.15{\pm}0.06cm^3$ on Multi plan. As a result, Differences of delineated mean target volume due to radiotherapy planning system was 3% to 6%. And overall mean target volume from CT scan images was 6.36% larger than those of MR scan images.

EFFECTS OF STR MGREN SPHERE ON LINE PROFILES OF 32 CYG WITH ALFV N WAVES DRIVEN WIND (STROMGREN 구가 ALFVEN파 항성풍을 가진 32 Cyg의 선윤곽에 미치는 효과)

  • 김경미;최규홍
    • Journal of Astronomy and Space Sciences
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    • v.15 no.1
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    • pp.101-110
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    • 1998
  • We calculated line profiles of 32 Cyg with an assumed $str{\"{o}}mgren$ sphere at orbital phases 0.06 and 0.78. The wind models with $Alfv\'{e}n$ waves show diminished line profiles compared to those of the models using power velocity laws. The reduced density of absorbers in HII region produce weak profiles, but line profiles at ${\phi}=0.06$ do not show the differences except in the red edge of absorption. At ${\phi}=0.78$ however, we could reproduce the line profiles of Alfven waves model by the power law models with two velocity gradients. It suggests that the power law model with 2 acceleration regions could reduce the errors in the theoretical line formation with no consideration of wind acceleration mechanism.nism.

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Segmentation-based tnage Coding Method without Need for Transmission of Contour Information (윤곽선 정보의 전송이 불필요한 분할기반 영상 부호화 방법)

  • Choi Jae Gark;Kang Hyun-Soo;Koh Chang-Rim;Kwon Oh-Jun;Lee Jong-Keuk
    • Journal of KIISE:Computer Systems and Theory
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    • v.32 no.5
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    • pp.187-195
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    • 2005
  • A new segmentation-based image coding method which no needs transmission of contour data is proposed. The shape information acts as bottleneck in the segmentation-based video coding because it has much portion of transmission data. The proposed method segments a previous decoded frame, instead of a current frame. As a result, there is no need for transmission of contour information to a decoder. Therefore, the saved bits can be assigned to encode other information such as error signals. As shown in experiment results, if data rate is very highly increased due to abrupt motion under very low bit rate coding having limited transmission bits, PSNR of conventional block-based method go down about 20dB, while the proposed method shows a good reconstruction quality without rapid PSNR drop.

Error Diagnosis of a Machine Tool by Circular Tests (원테스트를 통한 공작기계의 오차분석)

  • 안일혁;김성수;민경석;최우천;홍대희
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1162-1165
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    • 2003
  • Contouring errors are important especially for high speed and precision machining. Since the contouring errors of a machine tool affect the error of a machined part directly, it is necessary to find the contouring errors by some relevant tests. In this study, contouring errors are obtained by performing circular tests with a grid plate. Various error sources are diagnosed by a least square method.

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리니어모터 탑재 HMC의 운동특성 평가

  • 허남환;강은구;홍원표;최헌종;최우천
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.05a
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    • pp.328-328
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    • 2004
  • 최근의 생산시스템은 수요자의 요구에 맞추어 다종소량화 경향이 뚜렷해지고 부품 또는 제품의 다기능화 및 소형화가 급속하게 진전되고 있으며, 여기에 보조를 맞추어 제품의 고정밀화가 그 어느 때보다 강하게 요구되고 있다. 이에 따라 공작기계를 이용한 정밀 가공기술의 필요성이 증가하게 되었고 공작기계가 공작물의 가공정도에 미치는 영향에 대한 평가가 많은 관심을 모으고 있다. 이는 가공된 공작물의 정밀도는 그것을 가공한 공작기계의 정밀도에 의해 좌우되기 때문이다.(중략)

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A Path-Tracking Control of Optically Guided AGV Using Neurofuzzy Approach (뉴로퍼지방식 광유도식 무인반송차의 경로추종 제어)

  • Im, Il-Seon;Heo, Uk-Yeol
    • Journal of Institute of Control, Robotics and Systems
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    • v.7 no.9
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    • pp.723-732
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    • 2001
  • In this paper, the neurofuzzy controller of optically guided AGV is proposed to improve the path-tracking performance A differential steered AGV has front-side and rear-side optical sensors, which can identify the guiding path. Due to the discontinuity of measured data in optical sensors, optically guided AGVs break away easily from the guiding path and path-tracking performance is being degraded. Whenever the On/Off signals in the optical sensors are generated discontinuously, the motion errors can be measured and updated. After sensing, the variation of motion errors can be estimated continuously by the dead reckoning method according to left/right wheel angular velocity. We define the estimated contour error as the sum of the measured contour in the sensing error and the estimated variation of contour error after sensing. The neurofuzzy system consists of incorporating fuzzy controller and neural network. The center and width of fuzzy membership functions are adaptively adjusted by back-propagation learning to minimize th estimated contour error. The proposed control system can be compared with the traditional fuzzy control and decision system in their network structure and learning ability. The proposed control strategy is experience through simulated model to check the performance.

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Face Tracking Combining Active Contour Model and Color-Based Particle Filter (능동적 윤곽 모델과 색상 기반 파티클 필터를 결합한 얼굴 추적)

  • Kim, Jin-Yul;Jeong, Jae-Ki
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.10
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    • pp.2090-2101
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    • 2015
  • We propose a robust tracking method that combines the merits of ACM(active contour model) and the color-based PF(particle filter), effectively. In the proposed method, PF and ACM track the color distribution and the contour of the target, respectively, and Decision part merges the estimate results from the two trackers to determine the position and scale of the target and to update the target model. By controlling the internal energy of ACM based on the estimate of the position and scale from PF tracker, we can prevent the snake pointers from falsely converging to the background clutters. We appled the proposed method to track the head of person in video and have conducted computer experiments to analyze the errors of the estimated position and scale.

Efficient Data Acquisition Technique for Clinical Application of Multileaf Collimator (다엽콜리메이터의 임상적용을 위한 효율적인 정보 취득 기술)

  • Lee, Jae-Seung;Kim, Jung-Nam
    • The Journal of the Korea Contents Association
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    • v.8 no.11
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    • pp.182-188
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    • 2008
  • The MLC(multi leaf collimator) in charge of important role in radiation therapy field recently have been exchanging from shielding block into it rapidly, owing to being convenient. However, MLC can be occurred the leakage dose of inter_leaves and the error of algorithm in imput and output from digital signal. We compared the difference of imput method to MLC made by Varian Cop. with the error and effective field induced by MLC shaper and film scanner based on XimaVision value as using MLC layer of various shapes. According to comparing standard value with them to basic MLC layer (test1-5), MLC shaper was $0{\sim}0.29cm$, $0.23{\sim}3.59cm^2$ and film scanner was $0{\sim}0.78cm$, $0.24{\sim}3.89cm^2$. At the MLC layer to be applied in clinic, MLC shaper was $0{\sim}0.54cm$, $0.04{\sim}1.68cm^2$ and film scanner was $0{\sim}0.78cm$, $0.24{\sim}3.89cm^2$. The more distance and field from axis of central line increase, the more bigger the error value increases. There is a few mm error from standard point at the process which imput various information to apply MLC in clinic. and effective field did not have variation of monitor unit and dose owing to being a few cm2 error against real field. But there are some problem to shield critical organs because some part of target volume induced by the movement of organs can be not included, therefore we have to pay attention on the process to imput MLC layer

3-Axis Coupling Controller for High-Precision/High-Speed Contour Machining (고정밀 고속 윤곽가공을 위한 3축 연동제어기)

  • 지성철;구태훈
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.1
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    • pp.40-47
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    • 2004
  • This paper proposes a three-axis coupling controller designed to improve the contouring accuracy in machining of 3D nonlinear contours. The proposed coupling controller is based on an innovative 3D contour error model and a PID control law. The novel contour error model provides almost exact calculation of contour errors in real-time for arbitrary contours and can be integrated with any type of existing interpolator. In the proposed method, three axes of motion are coordinated by the proposed coupling controller along with a proportional controller for each axis. The proposed contour error model and coupling controller are evaluated through computer simulations. The simulation results show that the proposed 3-axis coupling controller with the new contour error model substantially can improve the contouring accuracy by order of magnitude compared with the existing uncoupled controllers in high-speed machining of nonlinear contours.