• The KIPS Transactions:PartB
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• v.12B no.5 s.101
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• pp.527-534
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• 2005

Rotation and scale variations make it difficult to solve the problem of shape description and recognition because these variations change the location of points composing the shape. However, some geometric Invariant points and the relations among them are not changed by these variations. Therefore, if points in image space depicted with the r-y coordinates system can be transformed into a new coordinates system that are invariant to rotation and scale, the problem of shape description and recognition becomes easier. This paper presents a shape description method via transformation from the image space into the invariant feature space having two axes: representing relative distance from a centroid and contour segment curvature(CSC). The relative distance describes how far a point departs from the centroid, and the CSC represents the degree of fluctuation in a contour segment. After transformation, mesh features were used to describe the shape mapped onto the feature space. Experimental results show that the proposed method is robust to rotation and scale variations.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.11a
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• pp.81-83
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• 2014

본 논문은 HD 해상도의 고화질 방송카메라(회전과 줌이 가능한)와 '키넥트' 같은 범용 모션인식 카메라를 연동하여 방송용 모션기반 증강현실 어플리케이션을 구현하기 위해서, 연기자의 위치를 가상 월드 좌표로 자동 변환시키는 방법을 제안한다. 방송환경에서 키넥트와 같은 모션인식카메라(RGB-D 카메라)를 사용하기 위해서는 거리와 조명의 영향을 많이 받아 연기자와 가까운 천장이나 카메라 밑처럼 그 설치 위치가 제약되곤 한다. 이때, 연기자와 그래픽의 정확한 합성을 위해, 모션인식 카메라로부터의 연기자 추적 정보를 월드 좌표계로 변환해야 하며, 이것을 수작업으로 하기에는 변환의 정확도가 많이 떨어지고 시간도 많이 소요된다. 본 논문에서는 체크박스 패턴 기반의 스테레오 카메라보정 알고리즘을 사용하여 모션인식카메라와 방송용 카메라간의 상관관계(이동, 회전)를 찾고, 이 값과 월드 좌표계 상의 방송 카메라(하드웨어 센서에 의해서 추적됨)정보(이동, 회전)를 이용하여 임의 위치에 설치한 모션인식 카메라로부터 추적된 연기자 위치정보를 월드 좌표계 상의 위치 값으로 자동 변환시키는 방법을 제안한다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.5
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• pp.475-482
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• 2008

This paper indicates that the use of Euler angles lacks in its consistency and exactness of analysis when it was applied to incorporate the rotational equation of motion for rotor systems by previous researcher. Kinetic energy and angular velocity are different from case to case depending on the way of choosing Euler angles and thus only the linear system has been investigated even though the rotor system has a very nonlinear behavior. A new methodology is applied by using both spherical coordinate and quaternion in the rotor rotation to overcome weaknesses of Euler angles and shows its superiority It is found through numerical examples that the use of quaternion will be a more useful and valid tool to derive the numerical model of the rotor system.

• Journal of the Korea Society of Computer and Information
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• v.16 no.8
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• pp.49-56
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• 2011

Recently, animation contents has become extensively available along with the development of cultural industry. In this paper, we propose a method to analyze a face of animation character and extract 3D rotational information of the face. The suggested method first generates a dominant color model of a face by learning the face image of animation character. Our system then detects the face and its components with the model, and establishes two coordinate systems: base coordinate system and target coordinate system. Our system estimates three dimensional rotational information of the animation character face using the geometric relationship of the two coordinate systems. Finally, in order to visually represent the extracted 3D information, a 3D face model in which the rotation information is reflected is displayed. In experiments, we show that our method can extract 3D rotation information of a character face reasonably.

• Proceedings of the Korea Multimedia Society Conference
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• 2004.05a
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• pp.275-278
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• 2004

지문 인식 방식은 기존의 영상 처리와는 달리 여러 가지 문제점을 포함하고 있다. 지문에는 기준 좌표축이 존재하지 않으므로 회전되어 채취된 지문에 대한 처리가 어려우며, 신체의 일부로서 유연성을 가지고 있어 채취될 때마다 모양이 달라 보이고, 지문이 손상될 수 있어 저 품질의 지문이 빈번히 발생할 수 있다 본 논문에서는 방향성의 흐름 패턴을 이용한 특이점 추출에 초점이 맞춰져 있으며 추출된 특이점 정보는 현재 구현되어진 특징점 추출 정보와 연계해 정합을 위한 기준점으로 활용한다. 기준점을 축으로 생성되어진 직교좌표는 지문 영상의 회전변위에 대한 영향을 최소화 하여 지문의 정합도를 높여준다.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.818-823
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• 2011

6-generalized coordinates of absolute translational displacements and angular displacements measured at Cartesian coordinates system fixed at the ground has been used to describe general dynamic behavior of a rigid body in mechanical systems. However, track coordinates system moving with the centerline of the track can be used to develop dynamic formulations for railway vehicle. It is easy to impose the constraints of track coordinates by the virtue of track coordinates system moving with track centerline. In this analysis, dynamic equations of railway vehicle by using track coordinates system is derived and the simulation results are presented.

• ICROS
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• v.17 no.3
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• pp.27-31
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• 2011

• Progress in Medical Physics
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• v.7 no.1
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• pp.53-64
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• 1996

Purpose: The purposes of this paper are to develop a theoretical basis that the beam directions should be considered when the mechanical accuracy of teletherapy machine is evaluated by the star pattern test, to develop methods using asymmetric field in length to simulate beam direction for the case that beam direction does not appear on film. Method: In evaluating mechanical rotational accuracy of the gantry of teletherapy unit by the star pattern test, the direction of radiation beams was considered. A star pattern using some narrow beams was made. Density profiles at 10cm far from estimated gantry axis on the star pattern were measured using an optical densitometer. On each profile, one coordimate of a beam axis was determined. A pair of coordinates on a beam axis form an equation of the axis. Assume that a unit vector equation omitted is with same direction as radiation beam and a vector equation omitted is a vector directing to the beam axis from the estimated gantry axis. Then, a vector product equation omitted ${\times}$ equation omitted is an area vector of which the absolute value is equal to the distance from the estimated gantry axis to the beam axis. The coordinate of gantry axis was obtained by using least-square method for the area vectors relative to the average of whole area vectors. For the axis, the maximum of absolute value of area vectors would be an accuracy of the gantry rotation axis. For the evaluation of mechanical accuracies of collimator and couch axes for which beam direction could not be depicted on a star pattern test film, narrow beams asymmetric in field length was used to simulate beam direction. Result: For a star test pattern to evaluate the mechanical accuracy of rotational axes of a telectherapy machine, the result considering beam direction was different from that ignoring beam direction. For the evaluation of mechanical accuracies of collimator and couch axes by means of a star pattern test, narrow asymmetric beams could simulate beam direction. Conclusion: When a star pattern test is used to evaluate the mechanical accuracy of a teletherapy unit, beam direction must be considered or simulated, and quantitatively evaluated.

• Geophysics and Geophysical Exploration
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• v.16 no.2
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• pp.91-96
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• 2013

This study proposes a method to correct inclination of instrument during exploration with a biaxial clinometer and GNSS compass. In 3-component magnetometry, measured vectors are ordinarily described in randomly inclined observation coordinate system due to movement, vibration, and shaking of instrument. Therefore, rotation angles of observation plane are needed to transform it into geodetic coordinate system. In this study, we measured inclination angles of observation plane by using 2-axis clinometer and GNSS compass, and derived proper parameters for rotational transform from them. We applied the conversion method to on-board 3-component magnetometry, and then transformed raw data into proper values on geodetic coordinate system.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.44-45
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• 2013

본 논문은 3상 PMSM 동작 중 한 개의 상이 고장이 났을 경우, 2상을 통하여 고장허용 동작을 하는데 있어서 발생하는 토크 리플 저감 방법에 대하여 연구를 하였다. 기존의 방법들이 기본파 주파수로 회전하는 동기좌표계상에서 전향 보상 방식으로 교류 성분의 전류를 제어함으로써 토크 리플을 보상하는 데에 반해 제안한 방법은 기본파 주파수의 2배수로 회전하는 동기좌표계상에서 직류 성분의 전류로 토크 리플을 보상하기 때문에, 저속 운전뿐만 아니라 고속 운전시에도 그 보상 특성이 매우 우수하다. 제안한 방법은 자동차용 전동식 조향 시스템에 적용하여 그 유효성을 실험적으로 검증하였다.