• ETRI Journal
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• v.38 no.6
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• pp.1114-1123
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• 2016

Multi-view video plus depth (MVD) has been widely used owing to its effectiveness in three-dimensional data representation. Using MVD, color videos with only a limited number of real viewpoints are compressed and transmitted along with captured or estimated depth videos. Because the synthesized views are generated from decoded real views, their original reference views do not exist at either the transmitter or receiver. Therefore, it is challenging to define an efficient metric to evaluate the quality of synthesized images. We propose a novel metric-the reduced-reference quality metric. First, the effects of depth distortion on the quality of synthesized images are analyzed. We then employ the high correlation between the local depth distortions and local color characteristics of the decoded depth and color images, respectively, to achieve an efficient depth quality metric for each real view. Finally, the objective quality metric of the synthesized views is obtained by combining all the depth quality metrics obtained from the decoded real views. The experimental results show that the proposed quality metric correlates very well with full reference image and video quality metrics.

• Journal of the Korean Ceramic Society
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• v.44 no.12
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• pp.696-702
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• 2007

The family of (Sr,Mg)-doped $LaGaO_3$ compounds, which exhibit high ionic conductivity at $600-800^{\circ}C$ over a wide range of oxygen partial pressure, appears to be promising as the electrolyte for intermediate temperature solid oxide fuel cells. Conventional synthesis routes of (Sr,Mg)-doped $LaGaO_3$ compounds based on solid state reaction have some problems such as the formation of impurity phases, long sintering time and Ga loss during high temperature sintering. Phase stability problem especially, the formation of additional phases at the grain boundary is detrimental to the electrical properties of the electrolyte. From this point of view, we focused to synthesize single phase (Sr,Mg)-doped $LaGaO_3$ electrolyte at the stage of powder synthesis and to apply relatively low heat-treatment temperature using novel synthesis route based on combustion method. The synthesized powder and sintered bulk electrolytes were characterized by XRD, TG-DTA, FT-IR and SEM. AC impedance spectroscopy was used to characterize the electrical transport properties of the electrolyte with the consideration of the contribution of the bulk lattice and grain boundary to the total conductivity. Finally, relationship between synthesis condition and electrical properties of the (Sr, Mg)-doped $LaGaO_3$ electrolytes was discussed with the consideration of phase analysis results.

• Journal of Broadcast Engineering
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• v.15 no.4
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• pp.540-546
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• 2010

Since the stereoscopic 3-dimensional (3D) video that provides users with a realistic multimedia service requires twice as much data as 2-dimensional (2D) video, it is difficult to construct the fast system. In this paper, we propose a fast stereoscopic 3D broadcasting system based on the depth information. Before the transmission, we encode the input 2D+depth video using x264, an open source H.264/AVC fast encoder to reduce the size of the data. At the receiver, we decode the transmitted bitstream in real time using a compute unified device architecture (CUDA) video decoder API on NVIDIA graphics processing unit (GPU). Then, we apply a fast view synthesis method that generates the virtual view using GPU. The proposed system can display the output video in both 2DTV and 3DTV. From the experiment, we verified that the proposed system can service the stereoscopic 3D contents in 24 frames per second at most.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.1023-1033
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• 2014

In this paper, performance improved hole-filling algorithm which includes the boundary noise removing pre-process that can be used for an arbitrary virtual view synthesis has been proposed. Boundary noise occurs due to the boundary mismatch between depth and texture images during the 3D warping process and it usually causes unusual defects in a generated virtual view. Common-hole is impossible to recover by using only a given original view as a reference and most of the conventional algorithms generate unnatural views that include constrained parts of the texture. To remove the boundary noise, we first find occlusion regions and expand these regions to the common-hole region in the synthesized view. Then, we fill the common-hole using the spiral weighted average algorithm and the gradient searching algorithm. The spiral weighted average algorithm keeps the boundary of each object well by using depth information and the gradient searching algorithm preserves the details. We tried to combine strong points of both the spiral weighted average algorithm and the gradient searching algorithm. We also tried to reduce the flickering defect that exists around the filled common-hole region by using a probability mask. The experimental results show that the proposed algorithm performs much better than the conventional algorithms.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.426-427
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• 2012

본 논문은 부호화된 저해상도의 깊이 영상과 고해상도의 색상 영상을 입력으로 고해상도의 깊이 영상을 생성하는 새로운 방법을 제안한다. 제안하는 방법은 결합 양측 필터를 이용하여 저해상도 깊이 영상의 경계 정보를 향상시킨다. 그런 다음, 깊이 영상 보간 단계에서 향상된 경계 정보를 참조하여 고품질 고해상도의 깊이 영상을 생성한다. 실험을 통한 깊이 영상과 합성영상의 화질 평가에서, 제안하는 방법이 기존의 3DV-ATM 깊이 영상 보간법보다 높은 성능을 보인다.

• Journal of Broadcast Engineering
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• v.12 no.2
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• pp.128-136
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• 2007

Since the multi-view video is a set of video sequences captured by multiple array cameras for the same three-dimensional scene, it can provide multiple viewpoint images using geometrical manipulation and intermediate view generation. Although multi-view video allows us to experience more realistic feeling with a wide range of images, the amount of data to be processed increases in proportion to the number of cameras. Therefore, we need to develop efficient coding methods. One of the possible approaches to multi-view video coding is to generate an intermediate image using view interpolation method and to use the interpolated image as an additional reference frame. The previous view interpolation method for multi-view video coding employs fixed size block matching over the pre-determined disparity search range. However, if the disparity search range is not proper, disparity error may occur. In this paper, we propose an efficient view interpolation method using initial disparity estimation, variable block-based estimation, and pixel-level estimation using adjusted search ranges. In addition, we propose a multi-view video coding method based on H.264/AVC to exploit the intermediate image. Intermediate images have been improved about $1{\sim}4dB$ using the proposed method compared to the previous view interpolation method, and the coding efficiency have been improved about 0.5 dB compared to the reference model.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.2
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• pp.43-51
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• 2014

Multi-view video including depth image is necessary to develop a new compression encoding technique for storage and transmission, because of a huge amount of data. Layered depth image is an efficient representation method of multi-view video data. This method makes a data structure that is synthesis of multi-view color and depth image. This efficient method to compress new contents is suggested to use layered depth image representation and to apply for video compression encoding by using 3D warping. This paper proposed enhanced compression method using layered depth image representation and H.264/AVC video coding technology. In experimental results, we confirmed high compression performance and good quality of reconstructed image.

• ETRI Journal
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• v.45 no.2
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• pp.291-303
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• 2023

Selfies are a popular form of photography. However, due to physical constraints, the compositions of selfies are limited. We present algorithms for creating virtual portraits with interesting compositions from a set of selfies. The selfies are taken at the same location while the user spins around. The scene is analyzed using multiple selfies to determine the locations of the camera, subject, and background. Then, a view from a virtual camera is synthesized. We present two use cases. After rearranging the distances between the camera, subject, and background, we render a virtual view from a camera with a longer focal length. Following that, changes in perspective and lens characteristics caused by new compositions and focal lengths are simulated. Second, a virtual panoramic view with a larger field of view is rendered, with the user's image placed in a preferred location. In our experiments, virtual portraits with a wide range of focal lengths were obtained using a device equipped with a lens that has only one focal length. The rendered portraits included compositions that would be photographed with actual lenses. Our proposed algorithms can provide new use cases in which selfie compositions are not limited by a camera's focal length or distance from the camera.

• The Journal of the Korea Contents Association
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• v.16 no.6
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• pp.507-515
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• 2016

In South Korea, there are a large number of tunnels because of the mountainous terrain, and to overcome this characteristics, lengths of tunnels are more longer than existing tunnels. The need to improvement current tunnel management contents is giving rise for accidents in tunnel section is continuously increased although lots of efforts to reduce the accidents. Conventionally, disaster prevention have been focused on the Tunnel Management Systems, tunnel operators generally tend to depend on CCTV images for most contents of detailed traffic flow managing. In this paper, investigation about current Tunnel Management Systems contents using IPA survey was conducted, and Priority Improvement Contents(Accident Situation Management Support, 2nd Accident Management Support, Traffic Flow Monitoring), which importance are high, but satisfaction are low, are deducted. Also, CCTV images, lack intuitive understanding, are judged as a main cause of low satisfaction of those contents. To overcome those limitations of the existing Tunnel Management Systems, this study sought to develop a technology for the synthesis of road images to derive traffic information from synthesis images, and the contents improvement stragegy is established. Tunnel operators-oriented satisfaction survey on new contents was carried out, and scored 4.2 on a 5-point scale. This has confirmed that the availability of new contents and at this stage, with pushing ahead of long-tunnels and undersea tunnels construction, politic applications are expected.

• Journal of Ocean Engineering and Technology
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• v.13 no.3B
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• pp.91-98
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• 1999

In order to reject the steady-state tracking error, it is common to introduce integral compensators in servosystems for constant reference signals. However, if the mathematical model of the plant is exact and no disturbance input exists, the integral compensation is not necessary. From this point of view, a two-degree-of-freedom(2DOF) servosystem has been proposed, in which the integral compensation is effective only when there is a modeling error or a disturbance input. The present paper considers a synthesis problems of this 32DOF servosystem with direct transfer term in the system representation. And, a method how we may obtain a gain such that desirable transient response is achieved, is proposed in the presence of the modelling error and disturbance input.