• 방송공학회논문지
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• 제16권1호
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• pp.44-53
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• 2011

본 논문에서는 depth layer partition을 이용한 2D 동영상의 자동 3D 변환 기법을 제안한다. 제안하는 기법에서는 먼저 2D 동영상의 장면 전환점을 검출하여 각각의 프레임 그룹을 설정하여 움직임 연산 과정에서의 오류 확산을 방지하여 깊이맵(depth map) 생성과 정에서 오차를 줄여준다. 깊이정보는 두 가지 방법으로 생성되는데 하나는 영역 분할과 움직임 정보를 이용하여 깊이맵을 추출하는 것이고 다른 하나는 에지 방향성 히스토그램(edge directional histogram)을 이용하는 방법이다. 제안하는 기법에서는 객체와 배경을 분리하는 depth layer partition 과정을 수행한 후 생성된 두 개의 깊이맵을 원 영상에 최적이 되도록 병합하게 된다. 제안된 기법으로 신뢰도 높은 깊이맵과 결과 영상을 생성할 수 있다는 것을 다양한 실험 결과를 통해 알 수 있다.

• International Journal of Contents
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• 제10권3호
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• pp.9-16
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• 2014

Depth-image-based rendering is generally used in real-time 2D-to-3D conversion for 3DTV. However, inaccurate depth maps cause flickering issues between image frames in a video sequence, resulting in eye fatigue while viewing 3DTV. To resolve this flickering issue, we propose a new 2D-to-3D conversion scheme based on fast and robust depth-map generation from a 2D video sequence. The proposed depth-map generation algorithm divides an input video sequence into several cuts using a color histogram. The initial depth of each cut is assigned based on a hypothesized depth-gradient model. The initial depth map of the current frame is refined using color and motion information. Thereafter, the depth map of the next frame is updated using the difference image to reduce depth flickering. The experimental results confirm that the proposed scheme performs real-time 2D-to-3D conversions effectively and reduces human eye fatigue.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권3호
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• pp.1159-1181
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• 2016

This study introduces an image-based 2D-to-3D conversion system that provides significant stereoscopic visual effects for humans. The linear and atmospheric perspective cues that compensate each other are employed to estimate depth information. Rather than retrieving a precise depth value for pixels from the depth cues, a direction angle of the image is estimated and then the depth gradient, in accordance with the direction angle, is integrated with superpixels to obtain the depth map. However, stereoscopic effects of synthesized views obtained from this depth map are limited and dissatisfy viewers. To obtain impressive visual effects, the viewer's main focus is considered, and thus salient object detection is performed to explore the significance region for visual attention. Then, the depth map is refined by locally modifying the depth values within the significance region. The refinement process not only maintains global depth consistency by correcting non-uniform depth values but also enhances the visual stereoscopic effect. Experimental results show that in subjective evaluation, the subjectively evaluated degree of satisfaction with the proposed method is approximately 7% greater than both existing commercial conversion software and state-of-the-art approach.

• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.35-60
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• 1997

Physical properties of composite resins such as strength, resistance to wear, discoloration, etc, depend on the degree of conversion of the resin components. The clinical behavior of restorative resins varies brand to brand. Part of this variation is associated with the filler and differences in the polymer matrix. The polymer matrix of resins may differ because the involved monomers are dissimilar and because of variation in the catalyst system. The purpose of this study was to evaluate the degree of conversion of the composite resins according to the depth of cure and light curing time. 7mm diameter cylindrical aluminum molds were filled with each of five different hybrid light curing composite resins(Z-100, Charisma, Herculite XRV, Prisma TPH, Veridonfil) on the thin resin films. The molds were 1mm, 2mm, 3mm, 4mm, and 5mm in depth to produce resin films of various heights. Each sample was given 20sec, 40sec, and 60sec illumination with a light source. The degree of conversion of carbon double bonds to single bonds in the resin films was examined by means of Fourier Transform Infrared Spectrometer. The results were obtained as follows; 1. There was difference in the degree of conversion among five light curing composite resins according to the depth of cure for 20sec, 40sec, and 60sec illumination with light source with statistical significance(P<0.05). 2. Five light curing composite resins show lower degree of conversion at surface of the resin than depth of 1mm. 3. The degree of conversion of five light curing composite resins was siginificantly reduced from the maximum for the resin film when the light passed through as little as 1mm of each composite. 4. The degree of conversion of five light curing composite resins decrease significantly at the depth of 4mm, and polymerization was not occured at the depth of 5mm except for Prisma TPH. 5. The degree of conversion of five light curing composite resins was increased with increased light curing time, and there was no significant differences in the degree of conversion above 4mm in Z-100, 3mm in Charisma, and at depth of 5mm in Herculite XRV and Veridonfil(P>0.05).

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.67-70
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• 2009

This paper proposes an algorithm for creating stereoscopic video from a monoscopic video. A viewer uses depth perception clues called a vanishing point which is the farthest from a viewer's viewpoint in order to perceive depth information from objects and surroundings thereof to the viewer. The viewer estimates the vanishing point with geometrical features in monoscopic images, and can perceive the depth information with the relationship between the position of the vanishing point and the viewer's viewpoint. In this paper, we propose a method to estimate a vanishing point with edge direction histogram in a general monoscopic image and to create a depth map depending on the position of the vanishing point. With the conversion method proposed through the experiment results, it is seen that stable stereoscopic conversion of a given monoscopic video is achieved.

• 한국광학회지
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• 제18권1호
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• pp.24-30
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• 2007

3차원 영상 재생을 위한 집적결상법에서 기본영상의 재조합을 통한 재생영상의 깊이변환에 관하여 연구하였다. 렌즈 배열 또는 카메라 배열 등을 통하여 획득된 영상 배열을 적절한 조건 하에서 재조합하여 재생함으로써 재생영상의 깊이에 대해 도치(pseudoscopic) 영상 또는 정치(orthoscopic) 영상, 허상, 실상 뿐만 아니라 임의의 깊이로의 왜곡 없는 변환이 가능하다. 본 논문에서는 각 변환에 대한 재조합 조건을 이론적으로 유도하고 실험을 통하여 확인하였다.

• Restorative Dentistry and Endodontics
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• 제20권1호
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• pp.33-54
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• 1995

The degree of conversion of composite resin was known to have influence on the mechanical properties of composite materials such as hardness, strength, wear resisitance, dimensional and color stability. Also unreacted monomer was reported to be harmful to the pulp. So the degree of conversion was a very important factor in the success of composite resin restorations. In recent, the dual cure resin cement was developed with the advocations that it could increase the curing rates in the sites where the curing ligt could not reach. Moreover many manufactors added some adhesive components in the resin cement. This study was undertaken to observe the effects of curing depth and light curing times on the degree of conversion of dual cure resin cements. CR INLAY CEMENT, DUAL CEMENT and OPTEC BOND, by the Fourier transform Infrared analysis, changing the curing depth 1mm, 2mm and 3mm, and varying the light curing time 20 seconds, 40 seconds and 80 seconds at each depth. The cytotoxicity of dual cure resin cements was tested by the in vitro MTT method using L929 cell. The results was evaluated and compared statistically. The results were obtained as follows : 1. The dual cure resin cements reavealed various degree of conversion, CR INLAY CEMENT and DUAL CEMENT had a tendency to be more reactive to the light cure and OPTEC BOND was a more chemical one. 2. CR INLAY CEMENT and DUAL CEMENT showed the lowest degree of conversion in 2 mm depth, and in 3mm depth the degree of conversion increased, which were due to the chemical cure of dual cures, but OPTEC BOND showed decreasing degree of conversion with increasing curing dept h and all experimental groups showed lower degree of conversion than CHEMICAL group which cured in dark room with no light, so the weak light-curing of dual cure resin cement prevented the chemical cure. (P<0.05) 3. CR INLAY CEMENT and DUAL CEMENT showed increasing degree of conversion in 1 mm and 3 mm, according to the increasing cure times, but in 2 mm depth the degree of conversion decreased with increasing light-curing times and OPTEC BOND showed contrary tendency, but there was no ststistical importance in the differences among the experimental group.(P>0.05) 4. The optical density by MTT assay of extractions of CR INLAY CEMENT, DUAL CEMENT and OPTEC BOND revealed no statitically important differences comparing with optical density of negative control.(P>0.05) 5. CR INLAY CEMENT showed a tendency of increaing cytotoxicity with days and DUAL CEMENT and OPTEC BOND showed higher cytotoxicity in 2 days than in 4 days, but there was no statistical importance in the differences.(P>0.05).

• 한국통신학회논문지
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• 제34권8C호
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• pp.782-789
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• 2009

본 논문에서는 2차원 단안 동영상으로부터 3차원 입체 동영상을 생성하는 기법을 제안한다. 3차원 공간에서 평행한 직선은 2차원 평면의 투시영상에서 먼 거리일수록 간격이 좁아져서 마지막에 한 점에서 만나게 되며, 이 점을 소실점(vanishing point)이라고 정의한다. 관찰자는 관찰자의 시점으로부터 가장 먼 지점인 소실점이라는 깊이 지도 지각 단서를 활용하여 객체와 배경으로부터 관찰자까지의 깊이 정보를 인지한다. 일반적으로 2차원 단안 영상에서의 기하학적 특성을 이용해서 소실점을 추정하고, 소실점의 위치와 관찰자의 시점과의 관계를 이용하여 깊이 정보를 인지할 수 있다. 본 논문에서는 일반적인 2차원 단안 영상에서 에지 방향성 히스토그램을 이용하여 소실점의 위치를 추정하고, 소실점의 위치에 따른 깊이지도(depth map)를 생성하는 방법은 제안한다. 실험 결과를 통해서 생성된 깊이지도를 이용하여 안정된 3차원 입체 동영상을 만들 수 있다.

• The Journal of Advanced Prosthodontics
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• 제6권3호
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• pp.194-199
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• 2014

PURPOSE. This study evaluated the depth of cure of resin composite cured by light through a translucent fiber post. MATERIALS AND METHODS. The opaque plastic tubes in various lengths of 2, 4, 6, 8, 10, 12, 14 mm. were filled with resin composite in which two different translucent fiber posts were inserted into the center and photo-polymerized for 40 seconds. The degree of conversion of the cured composite at bottom surface were examined using Fourier transform infrared attenuated total reflection spectrometer (FTIR/ATR) at 0.1, 0.5 and 1.0 mm apart from the post surface. RESULTS. The degree of conversion of the 0.1 mm, 0.5 mm, 1.0 mm apart from the post surface was highest at the 2 mm level and continuously decreased when the distance from the light source was increased and drastically decreased when the depth from the top of the post was greater than 4-6 mm. For each level, the highest degree of conversion was at 0.1 mm from the post surface and decreased continuously when the distance apart from the post surface was increased. CONCLUSION. The quantity of light transmission depends on the type of post and the light transmission capability of the post, especially after 4-6 mm depth and the area further apart from the post surface, are insufficient for clinical light activation of resin composite.

• 한국인터넷방송통신학회논문지
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• 제11권3호
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• pp.129-135
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• 2011

본 논문에서는 2D 동영상을 3D 입체영상으로 변환하기 위해서 머신러닝에 의한 학습기반의 객체분할과 객체의 optical flow를 활용하는 방법을 제안한다. 성공적인 3D 변환을 가능하게 하는 객체분할을 위해서, 객체의 칼라 및 텍스쳐 정보는 학습을 통해 반영하고 움직임이 있는 영역 위주로 객체분할을 수행할 수 있도록 optical flow를 도입한 새로운 에너지함수를 설계하도록 한다. 분할된 객체들에 대해 optical flow 크기에 따른 깊이맵을 추출하여 입체영상에 필요한 좌우 영상을 합성하여 생성하도록 한다. 제안한 기법으로 인해 효과적인 객체분할과 깊이맵을 생성하여 2D 동영상에서 3D 입체동영상으로 변환됨을 실험결과들이 보여준다.