• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.166-172
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• 2004

An underwater motion measurement system was constructed for applications to the model basin. A commercial motion capture system, FALCON of Motion Analysis Corp., which corrects automatically the distortion caused by refraction of the light passing through water and air, was adopted for underwater motion measurement. The modifications of FALCON system were performed: waterproofing camera housings, markers, connectors, and a new blue ring lighter. the accuracy of the motion measurement was obtained within the calibration error of 0.87mm in average and 0.89mm in standard deviation for the distance of 500mm between two markers on the calibration device. the volume of $2100mm(length)\times2100mm(breadth)\times2300mm(Height)$ was covered with 4 cameras of the underwater motion measurement system. For the performance verification, motion measurement test of a vertical mooring chain model excited at the top end was carried out. The 3D motions of mooring model were measured with variable amplitude and period of the forced excitation. Higher order motions of the mooring model were observed as the excitation period decreases. the performance of the system was verified by successfully measuring 3D motion of mooring model.

• Journal of the Korea Computer Graphics Society
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• v.19 no.4
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• pp.13-22
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• 2013

A motion capture system is widely used in movies, computer game, and computer animation industries because it allows for creating realistic human motions efficiently. The inertial motion capture system has several advantages over more popular vision-based systems in terms of the required space and cost. However, it suffers from low accuracy due to the relatively high noise levels of the inertial sensors. In particular, the accelerometer used for measuring gravity direction loses the accuracy when the sensor is moving with non-zero linear acceleration. In this paper, we propose a method to remove the linear acceleration component from the accelerometer data in order to improve the accuracy of measuring gravity direction. In addition, we develop a simple method to calibrate the joint axis of a link to which an inertial sensor belongs as well as the position of a sensor with respect to the link. The calibration enables attaching inertial sensors in an arbitrary position and orientation with respect to a link.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.379-381
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• 2008

본 논문에서는 가정용 비디오 게임에 사용 가능한 고속의 저가형 모션캡쳐, 시스템에 사용되는 전 방향 특성을 갖는 IR 능동 마커의 개발을 목표로 하고 있다. 현재 영화나 게임에서 모션캡쳐를 응용한 시스템 및 컨텐츠들이 많이 선보기고 있으며, 인기를 모으고 있는 추세이다. 이러한 흐름에 맞추어 우리는 이미 저가이면서 속도가 빠른 PSD(Position Sensitive Detector) 센서를 이용만 스테레오 비젼 기반의 PSD 모션캡쳐 시스템(Stereo vision based PSD motion capture system)과 광량 보정 기반의 단일 PSD 모션캡쳐 시스템(Intensity Calibration based single PSD motion capture system) 그리고 일정간격의 두 능동마커 기반의 단안 PSD 모션캡쳐 시스템(Two active markers at fixed distance based single PSD motion capture system)등을 소개한 바 있다. 본 논문에서 제안하는 전방향 특성을 갖는 IR 능동 마커는 일정간격의 두 능동마커 기반의 단안 PSD 모션캡쳐 시스템에 적용하여 보다 정밀한 3차원 좌표 측정을 할 수 있도록 한다. 이를 위해 본 논문에서는 동일 특성을 갖는 마커를 제작하고 평가하여 일정간격의 두 능동마커 기반의 단안 PSD 모션캡쳐 시스템에 적합한 마커의 제작 방법을 제안하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.4
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• pp.615-618
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• 2021

Recently, 3D reconstruction of real objects with multi-cameras has been widely used for many services such as VR/AR, motion capture, and plenoptic video generation. For accurate 3D reconstruction, geometry and color matching between multiple cameras will be needed. However, previous calibration and correction methods for geometry (internal and external parameters) and color (intensity) correction is difficult for non-majors to perform manually. In this paper, we propose a toolkit with procedural geometry calibration and color correction among cameras with different positions and types. Our toolkit consists of an easy user interface and turned out to be effective in setting up multi-cameras for reconstruction.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.507-510
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• 2003

In this paper, optical sensor system using PSD(Position Sensitive Detection) is proposed to obtain the three dimensional position of moving markers attached to human body. To find the coordinates of an moving marrer with stereo vision system, two different sight rays of an moving marker are required. Usually, those are acquired with two optical sensors synchronized at the same time. PSD sensor is used to measure the position of an incidence light in real-time. To get the three-dimension position of light source on moving markers, a conventional camera calibration method are used. In this research, we realized a low cost motion capture system. The proposed system shows high three-dimension measurement accuracy and fast sampling frequency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.587-588
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• 2022

In this paper, we propose a rigid body tracking method in 3D space using 2D passive marker images from multiple motion capture cameras. First, a calibration process using a chess board is performed to obtain the internal variables of individual cameras, and in the second calibration process, the triangular structure with three markers is moved so that all cameras can observe it, and then the accumulated data for each frame is calculated. Correction and update of relative position information between cameras. After that, the three-dimensional coordinates of the three markers were restored through the process of converting the coordinate system of each camera into the 3D world coordinate system, the distance between each marker was calculated, and the difference with the actual distance was compared. As a result, an error within an average of 2mm was measured.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.10
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• pp.1436-1443
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• 2013

A variety of studies on imitating the skeletal structure and the gait of legged animals have been done in order to develop walking robots which have an ability to adapt to atypical environments. In this paper, we analyzed the gait of a Bearded dragon lizard using the motion capture system, proposed a calibration scheme of the motion data and generated the trotting gait of a lizard based on the calibrated data. Also, we constructed the dynamic model based on the biometric data of a Bearded dragon lizard and applied the trotting gait of the lizard to the dynamic model. We verified the validity of the gait with the commercial dynamic simulation software.

• Journal of Sensor Science and Technology
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• v.27 no.2
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• pp.86-92
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• 2018

In recent times, motion capture technology using inertial measurement unit (IMU) sensors has been actively used in sports. In this study, we developed a canoe paddle, installed with an IMU and a water level sensor, as a system tool for training and calibration purposes in water sports. The hardware was fabricated to control an attitude heading reference system (AHRS) module, a water level sensor, a communication module, and a wireless charging circuit. We also developed an application program for the mobile device that processes paddling motion data from the paddling operation and also visualizes it. An AHRS module with acceleration, gyro, and geomagnetic sensors each having three axes, and a resistive water level sensor that senses the immersion depth in the water of the paddle represented the paddle motion. The motion data transmitted from the paddle device is internally decoded and classified by the application program in the mobile device to perform visualization and to operate functions of the mobile training/correction system. To conclude, we tried to provide mobile knowledge service through paddle sport data using this technique. The developed system works reasonably well to be used as a basic training and posture correction tool for paddle sports; the transmission delay time of the sensor system is measured within 90 ms, and it shows that there is no complication in its practical usage.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.5
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• pp.205-210
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• 2008

In previous paper, we introduced 3d acquisition system with CCD cameras, but it was not distinguished from other 3d acquisition system with PSD camera. In this paper, we introduce the 3d data acquisition system using by stereo method with two cameras, show the calibration method of two cameras, and present 3d acquisition methods. we tried to improve the accuracy of 3d data acquisition and implemented the proposed methods. According to the result, we found that the proposed algorithms can boost the accuracy highly against the previous works. The proposed methods are to remove distortion on input images and adjust z axis. We describes the performance in the result.

• Advances in aircraft and spacecraft science
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• v.9 no.5
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• pp.449-462
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• 2022

Space-telescopes placed in the Sun-Earth second Lagrange point (L2) observe the sky following a scan strategy that is usually based on a spin-precession motion. Knowing which regions of the sky will be more observed by the instrument is important for the science operations and the instrument calibration. Computing sky observation parameters numerically (discretizing time and the sky) can consume large amounts of time and computational resources, especially when high resolution isrequired.This problem becomesmore critical if quantities are evaluated at detector level instead of considering the instrument entire Field of View (FoV). In previous studies, the authors have derived analytic solutions for quantities that characterize the observation of each point in the sky in terms of observation time according to the scan strategy parameters and the instrument FoV. Analytic solutions allow to obtain results faster than using numerical methods as well as capture detailed characteristics which can be overseen due to discretization limitations. The original approach is based on the analytic expression of the instrument trace over the sky. Such equations are implicit and thusrequiresthe use of numeric solversto compute the quantities.In this work, a new and simpler approach for computing one ofsuch quantities(mean observation time) is presented.The quantity is first computed for pure spin motion and then the effect of the spin axis precession is incorporated under the assumption that the precession motion is slow compared to the spin motion.In this sense, this new approach further simplifies the analytic approach, sparing the use of numeric solvers, which reduces the complexity of the implementation and the computing time.