• 한국생산제조학회지
• /
• 제8권6호
• /
• pp.98-104
• /
• 1999

As the accuracy of manufactured goods needed high accuracy processing has made the efficiency of NC and measurement technology development, the innovation of machine tools has influence the development of the semi-conductor and optical technology. The movement errors can be expressed in terms of yaw, roll an pitch etc. In the case of expanding the error range, static, dynamic and servo gain errors can be included. Machining center might have twenty-one movement errs including three types of joint errors. Those errors have been measured on the condition of just loading of standard table. Regarding these measuring methods, the mechanical compliance of the structure has not been considered. In this paper, therefor, the influences of the additional load on the positioning accuracy are investigated. The results and the techniques proposed in this study can be considered very effective and useful to compensate more correctly the positioning motion.

• 대한방사선기술학회지:방사선기술과학
• /
• 제44권4호
• /
• pp.367-373
• /
• 2021

A quality assurance of computed tomography(CT) have done seven items that were water attenuation coefficient, noise, homogeneity, spatial resolution, contrast resolution, slice thickness, artifact using by standard phantom. But there is no quality assurance items and methods for CT simulator at domestic institutions yet. Therefore the study aimed to access the CT dose index(CTDI), table tilting, image distortion, laser accuracy, table movement accuracy and CT seven items for CT simulator quality assurance. The CTDI at the center of the head phantom was 0.81 for 80 kVp, 1.55 for 100 kVp, 2.50 for 120 mm, 0.22 for 80 kVp at the center of the body phantom, 0.469 for 100 kVp, and 0.81 for 120 kVp. The table tilting was within the tolerance range of ±1.0° or less. Image distortion had 1 mm distortion in the left and right images based on the center, and the laser accuracy was measured within ±2 mm tolerance. The purpose of this study is to improve the quality assurance items suitable for the current situation in Korea in order to protect the normal tissues during the radiation treatment process and manage the CT simulator that is implemented to find the location of the tumor more clearly. In order to improve the accuracy of the CT simulator when looking at the results, the error range of each item should be small. It is hoped that the quality assurance items of the CT simulator will be improved by suggesting the quality assurance direction of the CT simulator in this study, and the results of radiation therapy will also improve.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 1998년도 춘계학술대회 논문집
• /
• pp.143-147
• /
• 1998

As the accuracy of manufactured goods needed high-accuracy processing has made the efficiency of NC and measurment technology develop, the innovation of machine tools has influence the development of the semi-conductor and optical technology. We can mention that a traction role of the acceleration for the development like that depends on the development of the measurement technics - Stylus instrument method, STM, SEM, Laser interferometer method - which are used for measuring the movement accuracy of machine tools. The movement error factors in movement accuracy are expressed as yaw, roll, and pitch etc. Machining center has 21 movement error factors including of 3 axies joint errors because that has 3 axies and has been measured as the standard of the unloaded condition until now inspite of getting static, dynamic, and servo-gain errors in the case of expending the error range. Therefore, this study tries to measure position accuracy according to loading on the X-Y table of the machining center.

• 핵의학기술
• /
• 제13권3호
• /
• pp.86-91
• /
• 2009

전신 영상 검사는 일반적인 핵의학 검사에 적용되고 있는 가장 기본적인 촬영 방법 중 하나이다. 이 때 각 검사마다 규정화된 테이블 이동 속도는 다양하다. 본 연구에서는 감마카메라의 사용 기간에 따른 노후 상태와 감마카메라 테이블 위의 무게 변화에 따른 테이블 이동 속도를 측정하여 그 정확성을 분석하는데 그 목적이 있다. 2008년 12월부터 2009년 2월까지 서울아산병원 핵의학과내에서 전신 영상 검사를 주로 시행하는 SIEMENS 장비 중 가장 사용기간이 긴 ECAM plus와 가장 최근에 설치된 SYMBIA T2를 대상으로 연구를 실시하였다. 각 장비별로 테이블 이동속도를 10, 15, 30 cm/min으로 나누어 매 10 cm씩 마다 총 100 cm의 구간을 타이머를 이용해 테이블 이동 시간을 측정하였다. 또한 표준 체중을 60~70 kg으로 감안하여 0, 66, 110 kg으로 나누어 체중에 따른 테이블의 이동 속도를 동일한 방법으로 측정하여 비교 분석하였다. 본 연구에서는 10 cm/min, 15 cm/min, 30 cm/min의 변동계수가 ECAM plus에서 1.23, 1.42, 2.02이었고, SYMBIA T2에서 1.23, 1.83, 2.28이었으며 테이블 이동속도가 증가될수록 변동은 많았다. 또한 무게 변화에 따른 각각의 변동계수는 0 kg에서 0.96, 1.45, 2.08이었고, 66 kg에서 1.32, 1.72, 2.27이며, 110 kg에서 1.37, 1.73, 2.14로 무게에 따른 큰 차이는 없었다. 95% 신뢰수준에서 통계적으로 유의한 차이는 있지 않아(p>0.05) 두 장비 모두 허용할 수 있는 범위안에 있었지만, ECAM plus에 비해 SYMBIA T2의 변동계수가 비교적 크게 측정되었다. 이러한 결과를 미루어 볼 때 Onco. Flash와 같은 Half-time 검사법을 실시하기 전에는 테이블의 이동과 테이블 이동 속도, 감마카메라의 상태를 점검하고, 좀 더 관심을 기울여야 하며 정기적인 점검을 일반화시키는 것이 유용할 것이라고 생각된다.

• 한국공작기계학회논문집
• /
• 제13권6호
• /
• pp.41-47
• /
• 2004

This study is aimed to measure the deflection of loaded table on machine tool. The deflection rate is measured then the table is in a stationary state and is moved. In conclusion we have found that the more load increases, the more the table deflections. Also, we have found that the deflection rate increases in accordance with the speed of movement. Therefore, we have concluded that inspection of machine tool should be done considering the weight of load and the speed of movement. However, since the condition of accuracy test for domestic brand of machine tool is defined as unloaded case, measures should be explored only for loaded case.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
• /
• pp.844-847
• /
• 1996

This paper describes the servo position control for the 2-axis positioning table the servo controller consists of conventional feedback loops, disturbance observer. To reduce the contour error, which occurs in the multi-dimensions machines, cross-coupled controller(CCC) is suggested. A weak point of the CCC is their low effectiveness in dealing with arbitrary nonlinear contour such as circles and parabolas. This paper introduces a new nonlinear CCC that is based on control gains that vary during the contour movement The gains of CCC and adjusted in real time according to the shape of nonlinear contour. The feedback controller based on the disturbance observer compensated for external disturbance, plant uncertainty and bad effectiveness by friction model. Suggested servo controller which improve the contouring accuracy, apply to the 2-axis system. Simulation results on 2-axis table verify the effectiveness of the proposed servo controller.

• 한국생산제조학회지
• /
• 제21권3호
• /
• pp.465-472
• /
• 2012

This paper describes a new robust control algorithm which can be used to enhance the positioning performance of an ultra-precision positioning system. The working table is supported by flexure hinges and moved by a piezoelectric actuator, whose position is measured by an ultra-precise linear encoder. The system dynamics is very complicated because the movement of the table is governed by both the mechanical characteristics and those of the PZT actuator. So that, the dynamics of the stage was modeled roughly in this paper, and the overall system was formularized to solve the small gain problem. A series of experiments was conducted in order to verify the usefulness of the proposed algorithm. From the experimental results, the positioning performance such as the accuracy, the rise time and the hysteresis nonlinearity were greatly improved.

• 대한방사선치료학회지
• /
• 제21권2호
• /
• pp.89-95
• /
• 2009

목 적: 전산화단층촬영 모의치료기의 일일 정도 관리를 편리하고 신속하게 시행 할 수 있는 팬텀을 제작하여 유용성을 평가한다. 대상 및 방법: 폴리스타일렌 팬텀($250{\times}250{\times}100\;mm$)에 영상에서의 측정치와 실측정치의 정확성 확인을 위하여 홈($1{\times}100{\times}1\;mm$)을 만들었으며 테이블 이동의 정확성 평가를 위하여 중심부에서 위와 아래쪽 100 mm 지점에 직경 1 mm 크기의 홈을 만들어 방사선 비 투과 물질을 삽입하였다. 레이저의 정확성 평가를 위하여 팬텀 좌, 우측 수직선상에 십자 표시를 하였고 CT Number의 정확성 평가를 위하여 직경 25 mm, 깊이 50 mm의 원기둥 3개를 만들어 뼈 등가물질, 물, 공기를 삽입하였다. 제작한 팬텀을 전산화단층촬영 모의치료기(Brilliance BigBore, Philips, Netherlands)를 사용하여 촬영한 후(촬영조건 120 KVp, 100 mAs, 단면 두께 1 mm 연속촬영) 영상을 이용하여 측정치와 실측정치의 정확성, 테이블 이동, 레이저, CT Number의 정확성을 평가 하였다. 결 과: 제작한 팬텀을 이용하여 2008년 1월 7일부터 3월 7일까지 약 2개월 동안 본원에 설치되어 있는 전산화단층촬영 모의 치료기의 일일 정도관리에 사용해 본 결과 영상에서의 측정치와 실측정치의 정확성은 ${\pm}0.3\;mm$, 테이블 이동의 정확성은 ${\pm}0.3\;mm$, 레이저 정확성은 ${\pm}0.5\;mm$로 기준치인 ${\pm}1\;mm$ 오차범위 이내로 측정 되었으며 CT Number의 정확성 평가에서 뼈 등가 물질은 ${\pm}8\;HU$, 공기는 ${\pm}5\;$, 물은 ${\pm}5\;HU$로 기준치인 ${\pm}10\;HU$ 오차범위 이내로 측정되었다. 결 론: 본원에서 제작한 팬텀의 이용으로 신속하고 간편하게 레이저 장치의 정확성과 전산화단층촬영 모의치료기의 성능평가를 동시에 시행 할 수 있었으며 기존에 실시하던 일일 정도관리 항목에 영상을 이용한 평가 항목을 추가 보완함으로서 보다 정확한 치료 계획 과정을 수립 할 수 있을 것으로 사료된다.

• 한국운동역학회지
• /
• 제16권4호
• /
• pp.95-103
• /
• 2006

The purpose of this study was to review the relevant literature about coaching and thereupon, survey the coaching methods used for golf lesson to reinterpret them and thereby, describe in view of kinetics the swing errors committed frequently by amateur golfers and suggest more scientific golf coaching methods. For this purpose, kinetic elements were divided into accuracy and power ones and therewith, the variables affecting such elements were identified. For this study, a total of 60 amateur golfer were sampled, and their swing forms were photographed with two high-speed digital cameras, and the resultant images were analyzed to determine the errors of each form kinetically, which would be analyzed again with the program V1-5000. The kinetic elements could be identified as accuracy, power and accuracy & power. Thus, setup and trajectory were classified into accuracy elements, while differences of inter-joint angles, cocking and delayed hitting. Lastly, timing and axial movement were classified into accuracy & power elements. Three errors were identified in association with setup. The errors related with trajectory elements accounted for most (6) of the 20 errors. Three errors were determined for inter-joint angle differences, and one error was associated with cocking and delayed hitting. Lastly, one error was classified into timing error, while five errors were associated with axial movement. Finally, as a result of arranging the errors into a cross table, it was found that the errors were associated with each other between take-back and back-swing, take-back and follow-through, back-swing and back-swing top, and between back-swing and down-swing. Namely, an error would lead to other error repeatedly. So, it is more effective to identify all the errors for every form and correct them comprehensively rather than single out the errors and correct them one by one.

• 한국방사선학회논문지
• /
• 제16권2호
• /
• pp.151-156
• /
• 2022

적은 수의 광센서를 사용하는 검출기를 설계하고, 최대우도함수를 통해 감마선과 상호작용한 섬광 픽셀의 위치를 디지털 위치로 측정하는 연구를 수행하였다. 이를 위해 섬광체 내에서 빛의 이동을 모사할 수 있는 DETECT2000을 사용하여 시뮬레이션을 수행하였으며, 위치 측정의 정확도를 평가하였다. 6 × 6의 섬광 픽셀 배열과 4개의 광센서를 사용하여 검출기를 구성하였으며, 각 섬광 픽셀 중심에서 감마선 이벤트를 발생시켜 수집된 빛의 비율을 통해 순람표를 작성하였다. 새로운 위치에서 발생된 감마선 이벤트를 최대우도함수의 입력값으로 적용하여 순람표와 비교후 섬광 픽셀의 위치를 디지털 위치로 변환하였다. 모든 섬광 픽셀들에서 평가하였으며, 그 결과 99.1%의 높은 정확도를 획득하였다. 이러한 방법을 현재 사용되는 시스템에 적용할 경우 섬광 픽셀의 위치를 판별하는 과정의 간소화를 이룰 것으로 판단된다.