• Imaging Science in Dentistry
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• 제48권2호
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• pp.111-119
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• 2018

Purpose: This study was conducted to evaluate the accuracy of linear measurements of 3-dimensional (3D) images generated by cone-beam computed tomography (CBCT) and facial scanning systems, and to assess the effect of scanning parameters, such as CBCT exposure settings, on image quality. Materials and Methods: CBCT and facial scanning images of an anthropomorphic phantom showing 13 soft-tissue anatomical landmarks were used in the study. The distances between the anatomical landmarks on the phantom were measured to obtain a reference for evaluating the accuracy of the 3D facial soft-tissue images. The distances between the 3D image landmarks were measured using a 3D distance measurement tool. The effect of scanning parameters on CBCT image quality was evaluated by visually comparing images acquired under different exposure conditions, but at a constant threshold. Results: Comparison of the repeated direct phantom and image-based measurements revealed good reproducibility. There were no significant differences between the direct phantom and image-based measurements of the CBCT surface volume-rendered images. Five of the 15 measurements of the 3D facial scans were found to be significantly different from their corresponding direct phantom measurements(P<.05). The quality of the CBCT surface volume-rendered images acquired at a constant threshold varied across different exposure conditions. Conclusion: These results proved that existing 3D imaging techniques were satisfactorily accurate for clinical applications, and that optimizing the variables that affected image quality, such as the exposure parameters, was critical for image acquisition.

• 한국광학회:학술대회논문집
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• 한국광학회 2009년도 창립 20주년기념 특별학술발표회
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• pp.6-7
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• 2009

We proposed the two-dimensional (2D) / three-dimensional (3D) convertible modified integral imaging system using functional polarizing film named $imazer^{TM}$, which transfer or scatter the incident light ray according to the polarizing direction of ray. When the incident light rays transfer to $imazer^{TM}$, the rays generate 3D image through the process of the modified integral imaging system. However, the scattered light rays generate 2D image through the simple backlight scheme when the incident rays are scattered by the film. The proposed method can be implemented the partial 3D display system without any mechanical movements. In this paper, we propose and verify our system using some basic experiments and its results.

• 한국인터넷방송통신학회논문지
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• 제12권1호
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• pp.57-63
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• 2012

TIP기술은 2차원 그림 또는 한 장의 사진으로부터 기하정보를 추출하여 3차원 입체 효과를 만들어 영상 내부를 내비게이션 할 수 있는 기술로써, 게임, 엔터테인먼트, 교육, 홍보 등 다양한 응용분야에서 활용 가능한 기술이다. 본 논문에서는 android platform상에서의 OpenGL ES Library를 이용하여 확장된 TIP기술 적용 및 구현 방법을 제안한다. 제안 방법은 전경객체의 추출이 어려운 상황을 감안하여 보다 사실적 장면 구성이 용이하도록 사용자의 선택에 의한 소실점을 이용하고, OpenGL ES Library 를 이용하여 3차원 배경 모델을 획득한 후 이미지를 텍스처 매핑하여 3차원 가상공간을 완성한 후 카메라의 시점변환을 통해 이미지 내부를 내비게이션이 가능하도록 한다. 실험영상은 android platform상의 device에서 촬영한 이미지를 사용하여 android 2.1 및 OpenGL ES 1.0기반으로 구축된 제안 기술로 android platform의 스마트 device에서 적은 비용과 시간으로 다양한 응용개발에 적용 가능하도록 구현하였다.

• Journal of Yeungnam Medical Science
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• 제25권2호
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• pp.108-116
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• 2008

Background : When surgeons plan mandible ortho surgery for patients with skeletal class III facial asymmetry, they must be consider the exact method of surgery for correction of the facial asymmetry. Three-dimensional (3D) CT imaging is efficient in depicting specific structures in the craniofacial area. It reproduces actual measurements by minimizing errors from patient movement and allows for image magnification. Due to the rapid development of digital image technology and the expansion of treatment range, rapid progress has been made in the study of three-dimensional facial skeleton analysis. The purpose of this study was to conduct 3D CT image comparisons of mandible changes after mandibular surgery in facial asymmetry patients. Materials & methods : This study included 7 patients who underwent 3D CT before and after correction of facial asymmetry in the oral and maxillofacial surgery department of Yeungnam University Hospital between August 2002 and November 2005. Patients included 2 males and 5 females, with ages ranging from 16 years to 30 years (average 21.4 years). Frontal CT images were obtained before and after surgery, and changes in mandible angle and length were measured. Results : When we compared the measurements obtained before and after mandibular surgery in facial asymmetry patients, correction of facial asymmetry was identified on the "after" images. The mean difference between the right and left mandibular angles before mandibular surgery was $7^{\circ}$, whereas after mandibular surgery it was $1.5^{\circ}$. The right and left mandibular length ratios subtracted from 1 was 0.114 before mandibular surgery, while it was 0.036 after mandibular surgery. The differences were analyzed using the nonparametric test and the Wilcoxon signed ranks test (p<0.05). Conclusion: The system that has been developed produces an accurate three-dimensional representation of the skull, upon which individualized surgery of the skull and jaws is easily performed. The system also permits accurate measurement and monitoring of postsurgical changes to the face and jaws through reproducible and noninvasive means.

• 한국멀티미디어학회논문지
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• 제21권2호
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• pp.138-146
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• 2018

In this paper, we describe an algorithm for extracting depth information from a single image based on CNN. When acquiring three-dimensional information from a single two-dimensional image using a deep-learning technique, it is difficult to accurately predict the edge portion of the depth image because it is a part where the depth changes abruptly. in this paper, we introduce the concept of pixel-wise confidence to take advantage of these characteristics. We propose an algorithm that estimates depth information from a highly reliable flat part and propagates it to the edge part to improve the accuracy of depth estimation.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1996년도 Proceedings International Workshop on New Video Media Technology
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• pp.50-55
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• 1996

Multimedia boom has happened worldwide these days. In multimedia, we use several kinds of media such as character, figure, voice, music, still images, moving picture etc.. Then I think image including moving picture is the most effective and important media for human being. Creating digital images using a computer has the following two main approaches, depending on how the computer is used. 1. CG Technology. Created images, produced through computer graphics. 2. Digital Image Processing. Images processed through digital image processing technologies. Approach (1) is very popular as Computer Graphics. Two-dimensional and three-dimensional computer graphics techniques are used over wide applications today. On the other hand, Approach (2), which uses digital image processing technology, has been attracting attention lately, in the filed of movies and television. In this report, I will introduce these approaches of CG and digital image processing, and show some application fields such as current movies.

• 정보처리학회논문지D
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• 제12D권5호
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• pp.719-728
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• 2005

2DE는 조직 내의 단백질을 규명하는 단백질 분리 기술이다. 그러나 2DE 이미지는 실험 조건, 스캐닝 상태와 같은 환경에 민감하게 영향을 받는다. 이러한 이미지간의 변화를 극복하기 위해서 사용자는 각각의 서로 다른 이미지에 수동으로 기준점을 입력해주어야 한다. 그러나 이 과정은 에러를 발생시키며 긴 시간을 요구하는 작업으로, 빠른 분석에 장애 요인이 된다. 따라서 본 논문에서는 기준점 프로파일에 기반 하여 기준점을 자동으로 추출하는 방법을 개발하였다. 기준점 프로파일은 이미 확인된 이미지들의 기준점들에 대한 클러스터링 방법을 통하여 생성하며, 각 클러스터의 다양한 속성을 정의한다. 새로운 이미지가 입력되면 기준점의 후보 스팟들을 대상으로 프로파일과 비교하석 기준점을 추출한다. 그리고 $A^*$알고리즘을 이용하여 기준점 선정 과정을 최적화한다. 본 논문에서는 실제 사람의 간 조직 이미지를 이용하여 기준점 추출 방법의 성능을 분석하였다

• 한국산업융합학회 논문집
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• 제18권2호
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• pp.90-98
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• 2015

This research propose with image-based visual a new approach to design a feedback control of mobile robot. because mobile robot must be recharged periodically, it is necessary to detect and move to docking station. Generally, laser scanner is used for detect of position of docking station. CCD Camera is also used for this purpose. In case of using camera, the position-based visual servoing method is widely used. But position-based visual servoing method requires the accurate calibration and it is hard and complex work. Another method using cameras is inmage-based visual feedback. Recently, image based visual feedback is widely used for robotic application. But it has a problem that cannot have linear trajectory in the 3-dimensional space. Because of this weak point, image-based visual servoing has a limit for real application. in case of 2-dimensional movement on the plane, it has also similar problem. In order to solve this problem, we point out the main reason of the problem of the resolved rate control method that has been generally used in the image-based visual servoing and we propose an image-based visual feedback method that can reduce the curved trajectory of mobile robot in th cartesian space.

• 한국연소학회지
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• 제1권1호
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• pp.65-73
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• 1996

Flame propagation in a four-valve spark-ignition optical engine was visualized under lean-bum conditions with A/F=18 at 2000rpm. The early flame development in a four-valve pentroof-chamber single-cylinder engine was examined with imaging of the laser-induced Mie scattered light using an image-intensified CCD camera. Flame profiles along the line-of-sight were also visualized through a quartz piston window. Two-dimensional flame structures were visualized with a Proxitronic HF-1 fast motion camera system by Mie scattering from titanium dioxide particles along a planar laser sheet generated by a copper vapor laser. The flame propagation images were subsequently analysed with an image processing programme to obtain information about the flame structure under different tumble flow conditions generated by sleeved and non-sleeved intake ports. This allowed enhancement of the flame images and calculation of the enflamed area, and the displacement of its center, as a function of the tumble flow induced by the pentroof-chamber in the vicinity of spark plug. Image processing of the early flame development quantified the correlation between flame and flow characteristics near the spark plug at the time of ignition which has been known to be one of the most important factors in cyclic combustion variations in lean-burn engines. The results were also compared with direct flame images obtained from the natural flame luminosity of the lean mixture.

• 한국산학기술학회논문지
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• 제13권2호
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• pp.827-833
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• 2012

본 논문은 2D/3D 변환에서 깊이정보 생성을 위해 연산량을 감소시키는 레벨 간소화 기법을 적용하고 객체의 고유벡터를 이용하여 노이즈를 제거한 Optical flow를 이용하는 방법을 제안한다. Optical flow는 깊이정보를 생성하기 위한 방법 중 하나로 두 프레임간의 픽셀의 변화 벡터 값을 나타내어 움직임 정보를 나타내며 픽셀 단위로 처리하므로 정확도가 높다. 그러나 픽셀 단위 연산으로 긴 연산 시간이 소요되며 모든 픽셀을 연산하는 특성상 노이즈가 생길 수 있는 문제점이 있다. 본 논문에서는 이를 해결하기 위해 레벨 간소화 과정을 거쳐 연산 시간을 단축하였고 Optical flow를 영상에서 고유벡터를 갖는 영역에만 적용하여 노이즈를 제거한 뒤 배경 영역에 대한 깊이 정보를 에지 영상을 이용하여 생성하는 방법을 제안하였다. 제안한 방법으로 깊이정보를 생성한 뒤 DIBR(Depth Image Based Rendering)으로 2차원 영상을 3차원 입체 영상으로 변환하였고 SSIM(Structural SIMilarity index)으로 최종 생성된 영상의 오차율을 분석하였다.