• Journal of Periodontal and Implant Science
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• v.39 no.3
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• pp.375-381
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• 2009

Purpose: Root resection can be a valuable procedure when the tooth in question has a high strategic value. The prognosis of root resection has been well documented in previous studies, but the results focused on the palatal root resection have not been discussed in depth. I represent here the short term effectiveness of palatal root resection of maxillary first molars. Methods: Palatal root resection was performed on maxillary first molars of three patients. All the palatal roots were floating state on the radiographic finding and showed full probing depth and purulent exudation at initial examination. Reduction of palatal cusp and occlusal table was performed concomitantly. Endodontic therapy was completed after root resection. Results: Compromised maxillary first molars were treated successfully by palatal root resection in 3 cases. The mobility of resected tooth was decreased a little bit. The probing pocket depth of remaining buccal roots was not increased compared to initial depth. All the patients satisfied with comfort and cost effective results and the fact they could save their natural teeth. Conclusions: Within the above results, palatal root resection is an effective procedure treating compromised maxillary first molar showing advanced palatal bone loss to root apex with or without pulp involvement when proper case selection is performed.

• Journal of information and communication convergence engineering
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• v.12 no.3
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• pp.173-180
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• 2014

This paper investigates the robustness of watermarking techniques for stereo or multi-view images generated from texture and depth images. A three-dimensional (3D) warping technique is applied to texture and depth images to generate stereo or multi-view images for a 3D display. By using the 3D warping technique, in this paper, we developed watermarking techniques and evaluated the robustness of these techniques that can extract watermarks from texture images even when the viewpoints are moved. A depth image is used to generate a stereo image with the largest viewpoint difference to the left and right. The overlapping region in the stereo image that does not disappear after warping is then obtained, and DWT is applied to this region to embed a watermark in the LL sub-band. The proposed watermarking techniques were found to yield bit error rates of about 3%-16% when they were applied to stereo images generated from texture and depth images. Furthermore, the results showed that the copyright could be seen when the extracted watermark was visually confirmed.

• Journal of Broadcast Engineering
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• v.14 no.5
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• pp.601-615
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• 2009

This paper proposes an efficient depth-map coding method for generating virtual-view images in 3D-Video. Virtual-view images can be generated by the view-interpolation based on the depth-map of the image. A conventional video coding method such as H.264 has been used. However, a conventional video coding method does not consider the image characteristics of the depth-map. Therefore, this paper proposes an adaptive depth-map coding method that can select between the H.264/AVC coding scheme and the proposed gray-coded bit plane-based coding scheme in a unit of block. This improves the coding efficiency of the depth-map data. Simulation results show that the proposed method, in comparison with the H.264/AVC coding scheme, improves the average BD-rate savings by 7.43% and the average BD-PSNR gains by 0.5dB. It also improves the subjective picture quality of synthesized virtual-view images using decoded depth-maps.

• Journal of Broadcast Engineering
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• v.22 no.2
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• pp.193-206
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• 2017

In this paper, we propose a rate control method based on the $R-{\lambda}$ model that supports a parallel encoding structure in GOP levels or IDR period levels for 4K UHD input video in real-time. For this, a slice-level bit allocation method is proposed for parallel encoding instead of sequential encoding. When a rate control algorithm is applied in the GOP level or IDR period level parallelism, the information of how many bits are consumed cannot be shared among the frames belonging to a same frame level except the lowest frame level of the hierarchical B structure. Therefore, it is impossible to manage the bit budget with the existing bit allocation method. In order to solve this problem, we improve the bit allocation procedure of the conventional ones that allocate target bits sequentially according to the encoding order. That is, the proposed bit allocation strategy is to assign the target bits in GOPs first, then to distribute the assigned target bits from the lowest depth level to the highest depth level of the HEVC hierarchical B structure within each GOP. In addition, we proposed a processing method that is used to improve subjective image qualities by allocating the bits according to the coding complexities of the frames. Experimental results show that the proposed bit allocation method works well for frame-level parallel HEVC software encoders and it is confirmed that the performance of our rate controller can be improved with a more elaborate bit allocation strategy by using the preprocessing results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1155-1163
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• 2011

In this paper, we propose a new pre-processing algorithm applied to depth map to improve the coding efficiency. Now, 3DV/FTV group in the MPEG is working for standard of 3DVC(3D video coding), but compression method for depth map images are not confirmed yet. In the proposed algorithm, after dividing the histogram distribution of a given depth map by EM clustering method based on GMM, we classify the depth map into several layered images. Then, we apply different mean shift filter to each classified image according to the existence of background or foreground in it. In other words, we try to maximize the coding efficiency while keeping the boundary of each object and taking average operation toward inner field of the boundary. The experiments are performed with many test images and the results show that the proposed algorithm achieves bits reduction of 19% ~ 20% and computation time is also reduced.

• Tunnel and Underground Space
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• v.13 no.3
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• pp.196-206
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• 2003

In order to investigate the workability of Raise Boring Machine(RBM) such as utilization, penetration rate and advance rate, a vertical shaft of 98 m in length and 3.05 m in diameter was constructed in the layer of conglomerate by using the RBM in this study. In addition, field data from tow different construction sites including water-pump power plant tunnel, roadway tunnel and mining tunnel by RBM were collected and analyzed. The results show that the average weekly bored length is 19.3 m and its average utilization is between 54.3 % and 75.1 % very higher than that of the TBM(Tunnel Boring Machine). It also turns out that the bit force increases linearly with respect to the increase of the RPM(revolution per minute) of RBM. However, the net penetration rate decreases with the increase of bit force, RPM of RBM and depth of shaft. The findings of this study can be used to provide the useful information for the design of shaft and the selection of RBM.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.91-97
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• 2013

Image and it's processing techniques are widely applied and very important in the recent IT environment. In this paper, we try to reconstruct original BMP(Bitmap) image into indexed image and codebook utilizing vector quantization and represent high quality image only with same pixel depth of previous indexed image like JPEG etc. That is, By adopting common map method onto index image with $2^n$ color codebook, image can be represented as high quality as $2^{n+1}$ color codebook. When proposed output image is compared with original BMP image, it provides as much around 2dB as higher PSNR than conventional 8 bit index image(normal JPEG). Furthermore, this improvement(2 dB higher PSNR) could be provided when using the 9 bit indexed image.

• Journal of the Korean Vacuum Society
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• v.9 no.4
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• pp.373-378
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• 2000

There was a great difference in the formation kinetics of $TiO_2$ and $Bi_2O_3$ on silicon, but the growth of bismuth titanate (BIT) thin film was mainly limited by the formation of $TiO_2$. As a result, the BIT film was easy to be lack of bismuth. The pulse injection metalorganic chemical vapor deposition (MOCVD) process was introduced in order to overcome this problem by recovering the insufficient bismuth content in the film. By this pulse injection method, bismuth content was increased and also the uniform in-depth composition of the film was attained with a abrupt $Bi_4Ti_3O_{12}/Si$ interface. In addition, the crystallinity of $Bi_4Ti_3O_{12}$ thin film prepared by pulse injection process was greatly improved and the leakage current density was lowered by 1/2~1/3 of magnitude. Clockwise hysteresis of C-V was observed and the ferroelectric switching was confirmed for $Bi_4Ti_3O_{12}$ film deposited by pulse injection method.

• Broadcasting and Media Magazine
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• v.15 no.4
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• pp.123-134
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• 2010

차세대 비디오 코덱인 HEVC (High Efficiency Video Coding)는 높은 코딩 성능과 상대적으로 낮은 처리 복잡도를 제공하기 위해 표준화 과정을 통해 여러 가지 코딩 툴들을 검증하고 있다. 이 중 메모리압축기술은IBDI 적용에 따른 참조 메모리 크기 및 메모리 대역폭 증가를 줄이거나 또는 8 비트 연산일지라도 초고해상도를 다루는 HEVC 특성상 ME, MC 과정에서 발생하는 메모리 대역폭을 줄이기 위해 고안된 기술이다. 본 기고는 다양한 메모리 압축 기술들을 소개하고 코딩 성능 측면, 계산 복잡도 측면, 그리고 메모리 대역폭 감소 측면에서 각 기술들을 비교하고 향후 메모리 압축 기술의 전개방향에 대해 설명하고자 한다.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.285-288
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• 1998

Viterbi docoder is a maximum likelihood decoding method for convolution coding used in satellite and mobile communications. In this paper, a Viterbi decoder with constraint length of K=7, 3-soft decision and traceback depth of $\Gamma$=96 for convolution code is implemented using VHDL. The hardware size of designed decoder is reduced by 4 bit pre-traceback in the survivor memory.