• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.2
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• pp.128-133
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• 2015

This paper describes the construction of a static 3D ultrasonography image by tracking the radiation beam position during the handy operation of a 1D array probe to enable point-of-care use. The theoretical model of the transformation from the translational and rotational information of the sensor mounted on the probe to the reference Cartesian coordinate system was given. The signal amplification and serial communication interface module was made using a commercially available sensor. A test phantom was also made using silicone putty in a donut shape. During the movement of the hand-held probe, B-mode movie and sensor signals were recorded. B-mode images were periodically selected from the movie, and the gray levels of the pixels for each image were converted to the gray levels of 3D voxels. 3D and 2D images of arbitrary cross-section of the B-mode type were also constructed from the voxel data, and agreed well with the shape of the test phantom.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.3
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• pp.20-31
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• 2008

In this paper, we propose a single view-based technique for the estimation of human height and position. Conventional techniques for the estimation of 3D geometric information are based on the estimation of geometric cues such as vanishing point and vanishing line. The proposed technique, however, back-projects the image of moving object directly, and estimates the position and the height of the object in 3D space where its coordinate system is designated by a marker. Then, geometric errors are corrected by using geometric constraints provided by the marker. Unlike most of the conventional techniques, the proposed method offers a framework for simultaneous acquisition of height and position of an individual resident in the image. The accuracy and the robustness of our technique is verified on the experimental results of several real video sequences from outdoor environments.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.6 no.2
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• pp.121-131
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• 1986

The stiffness matrix of circularly curved frame elements including the warping effects is formulated by the solutions of vlasov's differential equations, and the procedure for the elastic static analysis of curved girder systems by the displacement method is presented. The validity of this method has been demonstrated by comparing the analysis results with other solutions. And if the tangential lines of the two frame element axes connected at any nodal point coincide, the transformation to the global coordinate system can be omitted when we analyze the structures consisting of circularly curved elements. The theory introduced in this thesis can be applied with sufficient accuracy to the structures built up with horizontally circular curved frame elements which have closed or open cross sections and are symmetric to the axis perpendicular to the plane of the curvature, such as prestressed concrete box girder bridges.

• Imaging Science in Dentistry
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• v.44 no.1
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• pp.15-20
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• 2014

Purpose: This study aimed to assess the three-dimensional (3D) facial changes after orthognathic surgery by evaluating the spherical coordinates of facial lines using 3D computed tomography (CT). Materials and Methods: A 19-year-old girl was diagnosed with class III malocclusion and facial asymmetry. Orthognathic surgery was performed after orthodontic treatment. Facial CT scans were taken before and after orthognathic surgery. The patient had a menton deviation of 12.72 mm before surgery and 0.83 mm after surgery. The spherical coordinates of four bilateral facial lines (ramal height, ramal lateral, ramal posterior and mandibular body) were estimated from CT scans before and after surgery on the deviated and opposite side. Results: The spherical coordinates of all facial lines changed after orthognathic surgery. Moreover, the bilateral differences of all facial lines changed after surgery, and no bilateral differences were zero. Conclusion: The spherical coordinate system was useful to compare differences between the presurgical and postsurgical changes to facial lines.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1959-1964
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• 2015

This research was focused on the analysis of navigation parameters from the received L1, C/A signal of the recent GPS, which has advanced with the SA policy change and the GPS modernization policy by the United States. It was done as a first step study for a comprehensive analysis on the multiple satellite navigation systems which will be adding or separating GPS signal. In particular, the statistical analysis on the GDOP change and positional accuracy based on the geocentric and spherical coordinate systems were investigated with carrier- to-noise ratio and the satellite geometry, The obtained GDOP values of HDOP, PDOP, VDOP are 0.5, 1.2, and 1.1, respectively in deviation. In addition, the positioning accuracies with these GDOP values were analyzed in the ellipsoidal and ECEF coordinates.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.9
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• pp.1615-1626
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• 1992

In this study, vibrations and resulting acoustic radiations from an elastic beam impacted by a steel ball were studied theoretically and experimentally. First the transverse vibrations of free-free elastic beams are analysed with modal analysis technique. The impact forces are modeled with the Hertz's theory and the contanct duration is compared with the measured values. Also the calculated beam vibrations are verified with the experimental results. Then the acoustic radiations due to the beam vibration are studied numberically and experimentally. The acousticpressure is calculated assuming the beam has an elliptical cross-section. The predicted acoustic pressure is compared with the measured value. It was found that both the predicted beamvibrations using the Hertz's theory and the estimated acoustic pressure under the assumption of an elliptical cross- section are in very good agreements with the measured values.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1950-1956
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• 2017

In food-printing field, precise positioning technique for a printing object is very important. In this paper, we propose cup positioning method for a latte-art printer through image processing. A camera sensor is installed on the upper side of the printer, and the image obtained from this is projected and converted into a top-view image. Then, the edge lines of the image is detected first, and then the coordinate of the center and the radius of the cup are detected through a Circular Hough transformation. The performance evaluation results show that the image processing time is 0.1 ~ 0.125 sec and the cup detection rate is 92.26%. This means that a cup is detected almost perfectly without affecting the whole latte-art printing time. The center point coordinates and radius values of cups detected by the proposed method show very small errors less than an average of 1.5 mm. Therefore, it seems that the problem of the printing position error is solved.

• The KIPS Transactions:PartD
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• v.12D no.1 s.97
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• pp.151-158
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• 2005

In order to use the existing map data base in the mobile phone, the dynamic creation technique of the radio map which will be able to be converted into the raster image and transmitted was proposed. We transferred the client module functions such as the coordinate conversion, data compression and decoding to server, and made driving of JAVA browser in the mobile phone which has the restricted resources possible for the dynamic creation of the radio map. We made the radio electronic map service possible without map data base for the mobile phone use only by performing the general work of the map at the sever. And we guaranteed the client waiting time less then the limit time by performing the filtering work of the map at the server also. After we input the keyword at the user interface for searching the region or facility, and verified the performance of the proposed technique by confirming that the raster electronic map usable at the mobile phone was created dynamically.

• Journal of Broadcast Engineering
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• v.4 no.2
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• pp.87-102
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• 1999

We propose an algorithm for augmenting a real video sequence with views of graphics ojbects without metric calibration of the video camera by representing the motion of the video camera in projective space. We define a virtual camera, through which views of graphics objects are generated. attached to the real camera by specifying image locations of the world coordinate system of the virtual world. The virtual camera is decomposed into calibration and motion components in order to make full use of graphics tools. The projective motion of the real camera recovered from image matches has a function of transferring the virtual camera and makes the virtual camera move according to the motion of the real camera. The virtual camera also follows the change of the internal parameters of the real camera. This paper shows theoretical and experimental results of our application of non-metric vision to augmented reality.

• Journal of Astronomy and Space Sciences
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• v.32 no.3
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• pp.229-235
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• 2015

We estimated the orbit of the Communication, Ocean and Meteorological Satellite (COMS), a Geostationary Earth Orbit (GEO) satellite, through data from actual optical observations using telescopes at the Sobaeksan Optical Astronomy Observatory (SOAO) of the Korea Astronomy and Space Science Institute (KASI), Optical Wide field Patrol (OWL) at KASI, and the Chungbuk National University Observatory (CNUO) from August 1, 2014, to January 13, 2015. The astrometric data of the satellite were extracted from the World Coordinate System (WCS) in the obtained images, and geometrically distorted errors were corrected. To handle the optically observed data, corrections were made for the observation time, light-travel time delay, shutter speed delay, and aberration. For final product, the sequential filter within the Orbit Determination Tool Kit (ODTK) was used for orbit estimation based on the results of optical observation. In addition, a comparative analysis was conducted between the precise orbit from the ephemeris of the COMS maintained by the satellite operator and the results of orbit estimation using optical observation. The orbits estimated in simulation agree with those estimated with actual optical observation data. The error in the results using optical observation data decreased with increasing number of observatories. Our results are useful for optimizing observation data for orbit estimation.