• Restorative Dentistry and Endodontics
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• v.17 no.1
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• pp.141-152
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• 1992

Four endodontic instruments from different manufacturers(K - file, Hedstrom - file, K - flex - file, Cavi - Endo) were used to shape 80 mesial canals of extracted posterior teeth. The instrument's ability to enlarge and shape the canals as the original canal shape was assessed by superimposing radiographs of canals obtained before and after canal shaping. The results were as follows 1. Hedstrom - file enlarged canals greater than K - file, K - flex - file, and Cavi - Endo(P<0.05). There are no differences in canal enlargement among K - flex, K - flex - file, and Cavi - Endo(P<0.05). 2. All the instruments showed no difference in canal enlargement between convex side and concave side of B point in proximal and clinical radiographic views, but at the concave side of C point canals were enlarged greater than at the convex side(proximal view of K - file: P<0.05, the others: P<0.01). 3. There was no difference m canal enlargement between convex side and concave side in proximal view of A and D points of K - file and K - flex - file(P<0.05). But in clinical view, canal enlargement at convex side of A point and concave side of D point was greater than that at concave side of A point and convex side of D point respectively. 4. Hedstrom - files showed greater canal enlargement at convex side of A points and concave side of D points (P<0.05 or P<0.01). Cavi - Endo showed no difference in canal enlargement between convex side and concave side at A and D points in proximal view(P<0.05). Bur canal enlargement was greater at concave side than at convex side of D point in clinical view. 5. K - file and Cavi - Endo showed no differences in canal enlargement between convex and concave side in proximal and clinical view (P<0.05). K - flex - file showed greater canal enlargement at concave side in proximal and clinical view(P<0.0:5). Hedstrom file showed no difference in canal enlargement between convex side and concave side in proximal view, but showed greater canal enlargement at concave side in clinical view(P<0.05).

• Journal of Electrical Engineering and Technology
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• v.11 no.4
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• pp.1003-1011
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• 2016

In this paper, a new algorithm by using 3D warping technique to effectively fill holes that are produced when creating a virtual-viewpoint image is proposed. A hole is defined as the region that cannot be seen in the reference view when a virtual view is created. In the proposed algorithm, to reduce the blurring effect that occurs on the hole region filled by conventional algorithms and to enhance the texture quality of the generated virtual view, Exemplar Based In-painting algorithm is used. The boundary noise which occurs in the initial virtual view obtained by 3D warping is also removed. After 3D warping, we estimate the relative location of the background to the holes and then pixels adjacent to the background are filled in priority to get better result by not using only adjacent object's information. Also, the temporal inconsistency between frames can be reduced by expanding the search region up to the previous frame when searching for most similar patch. The superiority of the proposed algorithm compared to the existing algorithms can be shown through the experimental results.

• Journal of Broadcast Engineering
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• v.21 no.1
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• pp.66-75
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• 2016

In this paper, we present a new method to reduce crosstalk of a glasses-free three-dimensional (3D) display using a multi-view image processing technique. Since crosstalk makes the current view image mixed with its neighboring ones, the output 3D image becomes severely blurred. We apply adaptive depth retargeting and view gradient-based crosstalk inverse filtering onto a multi-view image to minimize crosstalk of the glasses-free 3D display. In addition, overflow and underflow pixels are compensated by epipolar image pixel interpolation so that visual artifacts are minimized. Experimental results show that the proposed method reduces crosstalk more efficiently than the previous work while improving 3D image quality.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.24-32
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• 2006

본 논문에서는 다시점 카메라부터 획득된 부분적인 3D 점군을 사용하여 실내환경의 3D 복원을 위한 새로운 방법을 제안한다. 지금까지 다양한 양안차 추정 알고리즘이 제안되었으며, 이는 활용 가능한 깊이 영상이 다양함을 의미한다. 따라서, 본 논문에서는 일반화된 다시점 카메라를 이용하여 실내환경을 복원하는 방법을 다룬다. 첫 번째, 3D 점군들의 시간적 특성을 기반으로 변화량이 큰 3D 점들을 제거하고, 공간적 특성을 기반으로 주변의 3D 점을 참조하여 빈 영역을 채움으로써 깊이 영상 정제 과정을 수행한다. 두 번째, 연속된 두 시점에서의 3D 점군을 동일한 영상 평면으로 투영하고, 수정된 KLT (Kanade-Lucas-Tomasi) 특징 추적기를 사용하여 대응점을 찾는다. 그리고 대응점 간의 거리 오차를 최소화함으로써 정밀한 정합을 수행한다. 마지막으로, 여러 시점에서 획득된 3D 점군과 한 쌍의 2D 영상을 동시에 이용하여 3D 점들의 위치를 세밀하게 조절함으로써 최종적인 3D 모델을 생성한다. 제안된 방법은 대응점을 2D 영상 평면에서 찾음으로써 계산의 복잡도를 줄였으며, 3D 데이터의 정밀도가 낮은 경우에도 효과적으로 동작한다. 또한, 다시점 카메라를 이용함으로써 수 시점에서의 깊이 영상과 컬러 영상만으로도 실내환경 3D 복원이 가능하다. 제안된 방법은 네비게이션 뿐만 아니라 상호작용을 위한 3D 모델 생성에 활용될 수 있다.

• Journal of the Korean Society of Radiology
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• v.17 no.7
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• pp.1099-1108
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• 2023

The mortise view radiography procedure is an ankle joint examination and observes the presence of trauma, sprain, or dislocation suspected in the ankle joint. The auxiliary equipment used during the mortise view radiography procedure can generate artifacts in the radiograph images and is not diverse enough to be custom-made for each patient; not cost-efficient. The purpose of this study is to create a custom assistive device to support mortise view radiography procedure. This study utilized 3D printing technology to create the mortise view radiography procedure assistive device (ShinHan Device; SHD). The lengths of the tibiotalar joint (TTJ), talar calcaneal joint (TCJ), and medial joint (MJ) were measured and evaluated by five researchers using both SHD and the prototype Hologic tool. The mean ranges were found to be 39.42-39.47 mm for TTJ, 31.41-31.57 mm for TCJ, and 21.21-21.23 mm for MJ while using SHD device. On the other hand, the measurements showed mean ranges of 39.73-39.79 mm for TTJ, 31.46-31.50 mm for TCJ, and 21.31-21.35 mm for MJ while using the Hologic tool. Based on this study results, the error ranges at all positions decreased by 24% for TTJ, 17% for TCJ, and 36% for MJ when using SHD device compared to the Hologic tool. Moreover, when SHD was used, it allowed for a highly reproducible examination posture (ICC = 0.99), and it enabled the acquisition of radiograph images without artifacts, which were present in the Hologic tool.

• Journal of Sensor Science and Technology
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• v.16 no.2
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• pp.110-114
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• 2007

In this paper we present 3-D Navigation View, a three-dimensional visualization of indoor environment which serves as an intuitive and unified user interface for our developed indoor location tracking system via Virtual Reality Modeling Language (VRML) in web environment. The extracted user's spatial information from indoor location tracking system was further processed to facilitate the location indication in virtual 3-D indoor environment based on his location in physical world. External Authoring Interface (EAI) provided by VRML enables the integration of interactive 3-D graphics into web and direct communication with the encapsulated Java applet to update position and viewpoint of user periodically in 3-D indoor environment. As any web browser with VRML viewer plug-in is able to run the platform independent 3-D Navigation View, specialized and expensive hardware or software can be disregarded.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.76-77
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• 2022

In this paper, we propose a method to stabilize the 3D pose estimation result of a 3D volumetric data sequence by matching the pose estimation results from multi-view. Draw a circle centered on the volumetric model and project the model from the viewpoint at regular intervals. After performing Openpose 2D pose estimation on the projected 2D image, the 2D joint is matched to localize the 3D joint position. The tremor of 3D joints sequence according to the angular spacing was quantified and expressed in graphs, and the minimum conditions for stable results are suggested.

• Journal of Digital Contents Society
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• v.18 no.2
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• pp.383-392
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• 2017

This paper introduces a real-time 3D model generation system that can process in real time from multi-view image acquisition to image-based 3D model generation. This system describes how to collect, transmit, and manage the HD images input from 18 cameras and explain the background separation and smooth 3D volume model generation process. This paper proposes a new distributed data transmission and reception method for real-time processing of HD images input from 18 cameras. In addition, we describe a codebook-based background separating algorithm and a modified marching cube algorithm using perspective difference interpolation to generate smooth 3D models from multi-view images. The system is currently being built with a throughput rate of 30 frames per second.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.505-508
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• 2009

The super multi-view (SMV) display and the high-density directional (HDD) display were proposed as a natural 3D display that is free from the visual fatigue caused by the accommodation-vergence conflict and provides smooth motion parallax. The multi-projection system, the flat-panel system, and the time-multiplexing system are used to construct the HDD displays. The recent progress of the HDD 3D display is reviewed.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.203-204
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• 2007

In this work, we propose a compression algorithm for depth images, which are obtained from multi-view sequences. The proposed algorithm represents a depth image using a 3-D regular triangular mesh and predictively encodes the mesh vertices using a linear prediction scheme. The prediction errors are encoded with a arithmetic coder. Simulation results demonstrate that the proposed algorithm provides better performances than the JPEG2000 lossless coder.