• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.501-504
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• 2001

The use of error compensation techniques has been recognized as an effective way in the improvement of the accuracy of a machine tool. The laser measurement method for identifying position errors of machine tool has the disadvantages such as high cost, long calibration time and usage of volumetric error synthesis model. Accordingly, this paper deals with analysis of the position errors of a machine tool using ball bar test without using complicated error synthesis model. Statistical analysis method was adopted in this paper for deriving position errors using hemispherical helix ball bar test.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.437-441
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• 1997

In the conventional remote monitoring system, a user in front of a computer monitor can acquire only 2 dimensional visual information in a passive way. Thus, even thoght the user finds an interesting object from the video image, helshe can hardly acquire additional information on the object such as name. 311 shape, etc. In this paper, an active monitoring system that shows additional information on the selected object is proposed. The active remote monitoring system can calculate the 3D position of the object that is selected in the video images. Then, using the 3D position of the object, other information on the object can be retrieved from the database and shown on the screen. To calculate the 3D position of the object, 2 CCD cameras that can be tilted and panned using 3 stepping motors are used. The algorithm of 3D position calculation and the result of experiments are explained.

• 한국철도학회논문집
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• 제8권2호
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• pp.155-160
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• 2005

We propose a tram position estimation method for automatic train control system. The accurate train position should be continuously feedback to control system for safe and efficient operation of trains in railway. In this paper, we propose the sensor fusion method integrating a tachometer, a transponder, and a doppler sensor far estimation of train position. The external sensors(transponder, doppler sensor) are used to compensate for the error of internal sensor (tachometer). The Kalman filter is also applied to reduce the measurement error of the sensors. Simulation results are then presented to verify the usefulness of the proposed method.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.1005-1006
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• 2006

This paper proposes a method of position estimating through compensating the autonomous mobile robot's noise. Proposed method is that estimated position error by modified Kalman filter method using neural network. We use a neural network for measurement noise covariance and system noise covariance. In order to verify the effectiveness of the proposed method, we performed experiments for position estimation. The results show that convergence and position error is reduced than the Kalman filter method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.558-561
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• 2005

This paper describes a novel method of detecting excitation position in switched reluctance motor(SRM) drive. Some strategies of position sensorless control methods for the motor include the measurement of phase current and applied pulse voltage in an unexcited phase is suggested. The principle of the estimation of a rotor position is based on the detection of inductance by pulse currents. This sensorless method is very simple to detect excitation position estimation and gives efficient control of drive system. Suggested method is verified by some simulations.

• 제어로봇시스템학회논문지
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• 제12권9호
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• pp.856-860
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• 2006

A CCD camera is used to determine the position of the point sources that influence the measurement accuracy in the absolute interferometer. The principle of determination method is based on the GPS in which the position is determined by more than 3 distance information from the known positions. Two-dimensional array of photo-detectors in the CCD camera is used as known positions. Performing optimization of the cost function constructed with phase values measured at each pixel on the CCD camera, the position coordinates of each source is precisely determined.

• 드라이브 ㆍ 컨트롤
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• 제13권1호
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• pp.49-53
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• 2016

The accurate calculation of bucket tip position has a large influence on showing the motion of an excavator on the display device of the excavator and controlling the excavator automatically. It is generally known that Inertial Measurement Unit (IMU) sensors are more accurate than accelerometer-based sensors while the boom, arm or bucket moves because additional forces beyond gravity add additional acceleration to the sensors. To prove the accuracy difference between the two types of sensors, a position recognition system using an accelerometer-based sensor and an IMU sensor is implemented on the excavator. The experimental results show that the system using the IMU sensor significantly reduces the position recognition error while bucket moves and additional force beyond gravity exists.

• 대한방사선기술학회지:방사선기술과학
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• 제34권4호
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• pp.263-269
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• 2011

척추촬영법은 의료기관별로 상이하고 각종 대학 및 국가시험을 위한 교재 등에 상이하게 기술되어 혼선을 빚고 있는 실정이다. 이에 동일한 환자의 선자세와 누운자세에서 촬영한 영상을 바탕으로 각 자세에서 척추측만각과 척추전만각의 차이를 비교함으로써 임상 및 관련기관, 참고서적에 가장 적절한 촬영 자세를 정립하여 제시하고자 하였다. 2009년 3월부터 2011년 9월까지 척추질환 환자 중 수술적 치료를 받지 않은 85명을 대상으로 Cobb's method를 이용하여 척추전만각(lordortic angle) 및 척추측만각(scoliotic angle)을 측정하였다. 각각의 측정자료는 t-test(SPSS 18)를 이용하여 유의성을 분석하였으며, 임상의 실태 파악을 위해 서울소재 10곳의 대학병원을 대상으로 척추촬영의 자세와 시행근거를 설문으로 조사하였다. 척추측만각의 측정 결과, 선자세가 바로누운자세보다 평균 20.98% 증가하였으며, 통계적으로 매우 유의한 차이를 보였다(p<.01). 척추전만각은 지지대잡은자세가 측와위자세보다 29.3% 증가하였으며, 통계적으로 매우 유의하였다(p<.01). 의료기관의 실태 결과, 누운자세촬영이 70.0%로 선자세촬영의 30.0%보다 월등하게 나타났다. 결론적으로 선자세촬영은 누운자세촬영보다 척추측만각 및 척추전만각이 증가하여 임상적 진단과 치료에서 중력이 가해진 선자세 촬영의 중요성과 일치하였으므로 임상의 검사자는 그 차이를 인식하여 필히 정확한 선자세에서 촬영이 요구된다.

• Imaging Science in Dentistry
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• 제39권3호
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• pp.133-147
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• 2009

Purpose : To investigate the reproducibilities and compare the measurements in digital and MDCT-synthesized cephalometric radiograph, and to investigate the effect of head position on the measurement during imaging with MDCT. Materials and Methods : Twenty-two dry skulls (combined with mandible) were used in this study. Conventional digital cephalometric radiograph was taken in standard position, and MDCT was taken in standard position and two rotated position ($10^{\circ}$ left rotation and $10^{\circ}$ right tilting). MDCT data were imported in $OnDemand^{(R)}$ and lateral cephalometric radiograph were synthesized from 3D virtual models. Two types of rotated MDCT data were synthesized with default mode and with corrected mode using both ear rods. For all six images, sixteen angular and eleven linear measurements were made in V-$Ceph^{(R)}$ three times. Reproducibility of measurements was assessed using repeated measures ANOV A and ICC. Linear and angular measurements were compared between digital and five MDCT-synthesized images by Student t-test. Results : All measurements in six types of cephalometric radiograph were not statistically different under ICC examination. Measurements were not different between digital and MDCT-synthesized images (P>.05). Measurements in MDCT-synthesized image in $10^{\circ}$ left rotation or $10^{\circ}$ right tilting position showed possibility of difference from digital image in some measurements, and possibility of improvement via realignment of head position using both ear rods. Conclusion : MDCT-synthesized cephalometric radiograph can substitute conventional cephalometric radiograph. The error on head position during imaging with MDCT have possibility that can produce measurement errors with MDCT-synthesized image, and these position error can be corrected by realignment of the head position using both ear rods.

• 대한치과교정학회지
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• 제27권5호
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• pp.743-760
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• 1997

두개저의 크기, 형태 및 두부자세가 지니는 두개안면구조의 공간적 수평, 수직적 위치간의 상관성을 파악해 보고자 남자 51명, 여자 49명으로 구성된 표본으로부터 촬영된 100장의 측모 두부방사선사진을 이용, 12개의 계측항목과 37개의 기준점을 설정하고 계측항목에 대한 계측치와 기준점의 수평, 수직 위치를 산출한 다음,이들 간의 상관관계를 통계적으로 분석하였으며 계측항목에서 얻은 계측치의 크기가 크거나 작은 군을 각각 10개 표본씩으로 분류하여 mean facial diagram을 작성, 비교함으로서 다음과 같은 결론을 얻었다. 1. 두개저의 형태변수인 n-s-ba 및 n-s-ar각은 경추의 기준점 cv4ip, cv2ip, cv4tg 그리고 cv2ap의 수평, 수직적 위치 모두에 높은 통계적 유의성의 상관관계를 보였다($0.1\%$ 유의수준). 2. 두개저의 형태변수인 n-s-ba및 n-s-ar각은 안면구조에 있는 대부분의 기준점의 수평적 위치와 상관관계를 보였으나($1\%$ 유의수준), 수직적 위치는 통계적 유의성이 없었다($5\%$ 유의수준). 3. 두개저의 크기변수인 n-s, n-ba, n-ba및 n-ar의 크기는 두개안면구조내 기준점의 위치와 다양한 양상의 상관관계를 보였으나, 대체로 치아, 치조와 관련된 중안면구조의 수평, 수직적 위치와 상관관계가 높았다. 4. 두개저와 경추의 기울기가 이루는 자세변수인 NSL/CVT, NSL/OPT각은 두개안면구조내 기준점의 수평적 위치에 높은 상관성을 지니고 있었으며 통계학적 유의성이 인정되었으나($1\%$유의수준), 수직적 위치와는 통계적 유의성이 없었다($5\%$ 유의수준). 5. 진수평선(true horizontal line)과 경추의 기울기가 이루는 자세변수인 OPT/HOR 및 CVT/HOR각은 두개안면구조내 기준점의 수평, 수직적 위치 모두와 통계적으로 유의성이 인정되는 상관성을 보이지 않았다($5\%$ 유의수준). 6. 연조직에 존재하는 기준점의 수평, 수직적 위치는 모든 변수와의 상관성에서 대부분 경조직의 관련 기준점에 준하는 양상을 보였다.