• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.8
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• pp.1362-1370
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• 2008

This paper describes the design and characteristic analysis of a novel 3-DOF(Degree of Freedom) spherical motor. For multi DOF actuating, several numbers of motors have been used. By the using of normal motors they connected each other in single joint, is necessary to a several type of complex power transmission devices. The 3-DOF spherical motor can drive roll, pitch, and yaw motion in only one unit and it is not necessary to use additional gears and links parts. Therefore the using of 3-DOF spherical motor can eliminate; combined effects of inertia, backlash, non-linear friction, and elastic deformation of gears. In this paper, we propose the novel structured 3-DOF spherical motor and derive its principles of operation. Firstly, we designed concept model of novel structured 3-DOF spherical motor. Next, we derive the control method by calculating the currents. Also, to have intuitive driving control, we express the rotor position in equivalent angle-axis system and determine the exciting period of currents from the calculation result of the currents. To verify the control method, we calculated the currents by the position of rotor. and then we analyzed the characteristics by 3D Finite Element Method when the calculated currents are excited.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.8
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• pp.101-107
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• 2003

A new mechanical probe for 3-D feature measurement on coordinate measuring machines (CMMs) is presented. The probe is composed of the contact stylus and the three-component force sensor. With the stylus mounted on the force sensor, the probe can not only measure 3-D features, but also detect contact force acting on the stylus tip. Furthermore, the probing direction and the actual contact position can be determined by the relationship among three components of contact force to be detected. In this paper, transformation matrix representing the relationship between the external force acting on the stylus tip and the output voltages of measurement gauges is derived and calibrated. The prototype of probe is developed and its availability is investigated through the experimental setup for calibration test of the probe. A series of experimental results show that the proposed probe can be an effective means of improving the accuracy of touch probing on CMM.

• Journal of the Optical Society of Korea
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• v.19 no.3
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• pp.303-310
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• 2015

An image-space telecentric lens for an intra-oral 3D scanner was designed and fabricated for dental application. Since a telecentric function can provide the same results regardless of image plane position, it helps to realize a more accurate image for an intra-oral scanner. The performance of the designed lens meets the required properties for HD resolution. In particular, lateral color is corrected within 1 pixel. This system achieves depth of focus of more than 3 mm. For user convenience, the developed system consists of a prism part and an imaging part. Both parts are optimized to reduce the front size and weight of the system. In order to make the parallax sights, parallax angle was determined to be 8 degrees between two optical systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12C
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• pp.1154-1166
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• 2009

In this paper, we propose algorithms for generating high quality virtual intermediate views on the baseline or out of baseline. In this proposed algorithm, depth information as well as 3D warping technique is used to generate the virtual views. The coordinate of real 3D image is calculated from the depth information and geometrical characteristics of camera and the calculated 3D coordinate is projected to the 2D plane at arbitrary camera position and results in 2D virtual view image. Through the experiments, we could show that the generated virtual view image on the baseline by the proposed algorithm has better PSNR at least by 0.5dB and we also could cover the occluded regions more efficiently for the generated virtual view image out of baseline by the proposed algorithm.

• Korean Journal of Cognitive Science
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• v.22 no.2
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• pp.103-121
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• 2011

This study investigated how spatial dimension information and dimensional consistency between learning and testing phase would influence the target search performance. The participants learned spatial layouts of Lego blocks shown in either two- (2D) or three-dimension (3D) and were tested with the rotated stimuli ($0^{\circ}$, $90^{\circ}$, $180^{\circ}$, or $270^{\circ}$ from the initial view) in consistent or inconsistent dimension. Significantly better performance was observed when initial learning display appeared in 2D than in 3D. Particularly, the participants showed difficulties in flexible usage of spatial information presented in 3D especially if the dimensional information in the testing phase also was 3D and required mental rotation. The present study indicates that spatial map presented in 2D may be more useful than 3D in driving situations in which acquired spatial information from navigating device, such as GPS, and location of driver continuously changes.

• Journal of radiological science and technology
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• v.45 no.4
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• pp.313-320
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• 2022

Both angiography and interventional procedures accompanied by angiography provide many diagnostic and therapeutic benefits to patients and are rapidly increasing. However, unlike general radiography or computed tomography using the same X-ray, the amount of radiation is quite high, but the dose range can vary considerably for each patient and operator. The high sensitivity of the lens to radiation during cerebral angiography and neurointervention is already well known, and although there are many related studies, it is insufficient to easily reduce radiation in diagnosis and treatment. In this situation, in particular, by adding three-dimensional rotational angiography (3D-RA) to the existing two-dimensional (2D) angiography, it is now possible to make an accurate diagnosis. However, since this 3D-RA acquires images through projection of more radiation than before, the exposure dose of the lens may be higher. Therefore, we tried to analyze whether the radiation dose of the lens can be reduced by moving the lens out of the field range by adjusting the table height and magnification ratio during the examination using 3D-RA. The surface dose was measured using a rando phantom and a radiophotoluminescent glass dosimeter (PLD) and the radiation dose was compared by adjusting the table height and magnification ratio based on the central point. As a result, it was found that the radiation dose of the lens decreased as the table height increased from the central point, that is, as the lens was out of the field of view. In conclusion, in 3D-RA, moving the table position of about 2 cm in height will make a significant contribution to the dose reduction of the lens, and it was confirmed that adjusting the magnification ratio can also reduce the surface dose of the lens.

• Journal of Digital Contents Society
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• v.9 no.2
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• pp.203-211
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• 2008

Due to the advance of H/W and S/W techniques to play 3D sound, the virtual space contented by 3D graphics and sounds can provide users more improved realities and vividness. However for the small 3D contents developers and companies, it is hard to implement 3D sound techniques because the implementation requires expensive sound engines, 3D sound technical understanding and 3D sound programming skills. Therefore 3D-sound-playing-interface is necessary to easy and cost-effective 3D sound implementation. Using this interface, graphics experts can easily add 3D sound techniques to their applications. In this paper, the followings are designed and implemented as a preliminary stage in the way of developing the 3D sound playing interface. First, we develop 3D sound S/W modules converting mono to 3D sound in PC based systems. Second, we develop the interconnection modules to map 3D graphic objects and sound sources. The developed modules in this paper can allow the user to percept sound source position and surround effect at the moving positions in the virtual world. In the coming works, we are going to develop the more completed 3D sound playing interface consisted of the synchronization technique for sound and moving objects, and HRTF.

• Geophysics and Geophysical Exploration
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• v.11 no.3
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• pp.214-220
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• 2008

The distortion effect of electrical response for two-dimensional (2-D) DC resistivity method was verified in terms of 2-D inversion result of synthetic data obtained by three-dimensional (3-D) modeling, which is frequently applied to assess the safety of center core-type fill dam structure. The distortion effect is due to 2-D interpretation for 3-D structure. By the modeling analysis, we found that the water level is correctly described in the resistivity section around the middle part rather than each end side of the embankment due to the 3-D terrain effect, when the material of the embankment is assumed as horizontally uniform. And when we set the slope of outer rock fill part as uniform. the sharper the slope of the center core is, the more similar the resistivity section reflects. On the other hand, when the slope of the rock fill is steep, the resistivity section shows the water level at lower position than the real one, and the 3-D distortion effect at the end side of the embankment was enhanced.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.11
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• pp.881-888
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• 2020

In this paper, research on estimation of states of a target of interest using Line Of Sight(LOS) angle measurement is performed. Target's position, velocity, and acceleration are chosen to be the states of interests. The LOS measurement is known to be highly non-linear, making target dynamic modeling hard to be implemented into a filter. To solve this issue, the Pseudomeasurement equation was applied to the LOS measurement equation. With the help of this equation, 3D variable turn target dynamic model is applied to the filter model. For better performance, Kinematic Constraint is also implemented into the filter model. As for the filter, Bias Compensation Pseudomeasurement Filter (BCPMF) is used which is known for its robustness to initial conditions. Moreover, Two-Stage Kalman Filter (TSKF) form was also implemented to benefit from the parallel computation. As a result, TBCPMF 3DVT-KC is proposed and simulated to assess performance.

• Journal of Korean Dental Science
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• v.7 no.2
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• pp.66-79
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• 2014

Purpose: To analyze the amount and pattern of tooth movement and the changes in arch dimension of mandibular dentition after orthodontic treatment using a new three-dimensional (3D)-indirect superimposition method. Materials and Methods: The samples consisted of fifteen adult patients with class I bialveolar protrusion and minimal anterior crowding, treated by extraction of four first premolars with conventional sliding mechanics. After superimposition of 3D-virtual maxillary models before and after treatment using best-fit method, 3D-virtual mandibular model at each stage was placed into a common coordinate of superimposition using 3D-bite information, which resulted in 3D-indirect superimposition for mandibular dentition. The changes in mandibular dental and arch dimensional variables were measured with Rapidform 2006 (INUS Technology). Paired t-test was used for statistical analysis. Result: The anterior teeth moved backward, displaced laterally, and inclined lingually. The posterior teeth showed statistically significant contraction toward midsagittal plane. The amounts of backward movement of anterior teeth and forward movement of posterior teeth showed a ratio of 6 : 1. Although the inter-canine width increased slightly (0.8 mm, P<0.05), the inter-second premolar, inter-first molar, and inter-second molar widths decreased significantly with similar amounts (2.2 mm, P<0.05; 2.3 mm, P<0.01; 2.3 mm, P<0.001). The molar depth decreased (6.7 mm, P<0.001) but canine depth did not change. Conclusion: A new 3D-indirect superimposition of the mandibular dentitions using best-fit method and 3D-bite information can present a guideline for virtual treatment planning in terms of tooth position and arch dimension.