• The korean journal of orthodontics
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• v.26 no.5 s.58
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• pp.613-622
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• 1996

The purposes of this study were to evaluate and compare the frequency of ceramic bracket fracture, frequency of enamel fracture, bond fracture site, adhesive remnant index after mechanical and electrothermal debracketing, to evaluate effectiveness of high and low speed rotary instrument and ultrasonic instrument during residual adhesive remnants removal, and to measure resin film surface(percentage) using by image analyser(Leco 300). Bond fracture site, bracket fracture, and enamel surface damage were examined by scanning electron microscope. The following results were obained : 1. In the mechanical debracketing group, the bond failed predominantly at enamel-adhesive interface with the bulk of adhesive remaining on bracket base. 2. In the eletrothermal debracketing group, the bond failed predominantly at adhesive-bracket interface with the bulk of adhesive remaining on enamel surface. 3. The most effectiveness of residual resin removal was obtained by means of the resin polishing bur and the order of scratch formation was the procedure using tungsten carbide bur, ultrasonic scaler, sof-lex disc, and polishing bur. 4. The order of the resin film surface percentage was ultrasonic scaler, tungsten carbide bur, sof-lex disc, and resin polishing bur.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12B
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• pp.2369-2381
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• 1999

In this paper, we propose an iterative algorithm for reducing the blocking artifact in block transform-coded images by using a wavelet transform. In the proposed method, an image is considered as a set of one-dimensional horizontal and vertical signals and one-dimensional wavelet transform is utilized in which the mother wavelet is the first order derivative of a Gaussian like function. The blocking artifact is reduced by removing the blocking component, that causes the variance at the block boundary position in the first scale wavelet domain to be abnormally higher than those at the other positions, using a minimum mean square error (MMSE) filter in the wavelet domain. This filter minimizes the MSE between the ideal blocking component-free signal and the restored signal in the neighborhood of block boundaries in the wavelet domain. It also uses local variance in the wavelet domain for pixel adaptive processing. The filtering and the projection onto a convex set of quantization constraint are iteratively performed in alternating fashion. Experimental results show that the proposed method yields not only a PSNR improvement of about 0.56-1.07 dB, but also subjective quality nearly free of the blocking artifact and edge blur.

• Smart Media Journal
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• v.1 no.3
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• pp.36-42
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• 2012

Recently, the smart applications, such as smart phone and smart TV, become a hot issue in IT consumer markets. In particular, the smart TV provides 3D video services, hence efficient coding methods for 3D video data are required. Three-dimensional (3D) video involves stereoscopic or multi-view images to provide depth experience through 3D display systems. Binocular cues are perceived by rendering proper viewpoint images obtained at slightly different view angles. Since the number of viewpoints of the multi-view video is limited, 3D display devices should generate arbitrary viewpoint images using available adjacent view images. In this paper, after we explain a view synthesis method briefly, we propose a new algorithm to compensate view synthesis errors around object boundaries. We describe a 3D warping technique exploiting the depth map for viewpoint shifting and a hole filling method using multi-view images. Then, we propose an algorithm to remove boundary noises that are generated due to mismatches of object edges in the color and depth images. The proposed method reduces annoying boundary noises near object edges by replacing erroneous textures with alternative textures from the other reference image. Using the proposed method, we can generate perceptually inproved images for 3D video systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.8
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• pp.1931-1940
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• 2014

In this paper, we propose a new hand shape recognition algorithm based on the geometric features using the convex-hull from the depth image acquired by Kinect system. Kinect is a camera providing a depth image and user's skeleton information and used for detecting hand region. In the proposed algorithm, hand region is detected in a depth image acquired by Kinect and convex-hull of the region is found. Boundary points caused by noise and unnecessary points for recognition are eliminated in the convex-hull that changes depending on hand shape. Hand shape is recognized by the sum of internal angle of a polygon that is matched with convex-hull reconstructed with selected boundary points. Through experiments, we confirm that proposed algorithm shows high recognition rate not only for five models but also those cases rotated.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.153-158
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• 2001

본 논문에서는 해프톤 패턴의 간섭현상으로 발생하는 모아레 패턴을 효과적으로 제거할 수 있는 새로운 모아레 패턴 평활화 방법을 제시한다. 제안한 방법에서는 모아레 패턴이 존재하는 영역에 대해서만 그 세기에 따라 평활화 정도를 적극적으로 조정해 주기 때문에, 모아레 패턴을 효과적으로 제거하면서 경계나 텍스쳐 같은 의미있는 고주파 성분도 잘 보존할 수 있다. 또한 기존의 방법과 달리 퓨리에 변환과 같은 추가 연산을 필요로 하지 않고 미리 만들어진 테이블을 참조하는 과정만으로 모아레 피크의 세기를 결정하기 때문에 연산 시간 측면에 서로 효율적이다. 제안한 방법은 칼라 인쇄물을 다루는 다양한 멀티미디어 분야에서 유용하게 활용될 수 있다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.1
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• pp.1-8
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• 2002

The color interpolation scheme can play an important role in overcoming the physical limitation of the CCD image sensor and in increasing the resolution of color signals, while most conventional approaches result in blurred edges and false color artifacts. In this paper, we have proposed an improved edge-adaptive color interpolation scheme for a progressive scan CCD image sensor with RGB color filter array The edge indicator function proposed utilizes not only the within-channel correlation but also the cross-channel correlation, and reflects the edge characteristics of an image adaptively. The color components unavailable for at each channel are interpolated along the edge direction, not across the edges, so that aliasing artifacts are supressed. Furthermore, we eliminated false color artifacts resulting from the color image formation model in the edge-adaptive color interpolation scheme by adopting the switching algorithm based on the color edge detection. Simulation results of the proposed algorithm indicate that the improved edge-adaptive color interpolation scheme produces quantitatively better and visually more pleasing results than conventional approaches.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.19 no.4
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• pp.365-372
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• 2001

The general rule of boundary delimitation is a the principle of equidistant. The principle of equidistant is a method that determine boundary delimitation from fixed distant of baseline or basepoint. In this paper, study Two-Point Algorithm and Three-Point Algorithm that are widely used. and developed the Boundary Delimitation Program to verify the result and error. This program is specially useful for maritime boundary delimitation problem because there is no artificial and natural object in sea to determine boundary. As a result The mid-points computed on Ellipsoid have small error rather than mid-points on plane or sphere without any distortion by map projection. Through developing boundary delimitation program, can eliminate the various manipulation error using paper map, and quickly cope with maritime boundary delimitation negotiation. Also, verify that the error of basepoint in baseline is propagate the mid-point in mid-line, and determine suitable reference plane.

• Magazine of the Korea Concrete Institute
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• v.8 no.6
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• pp.205-212
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• 1996

This paper presents progressive fracture analysis of concrete using boundary element method and its stabilizing technique. To determine ultimate strength and to predict nonlinear behavior of concrete during progressive crack growth, the modelling of fracture process zone is done based on Dugdale-Barenblatt model with linear tension-softening curve. We regulate displacement and traction boundary integral equation of solids including crack boundary and analyze progressive fracture of concrete beam and compact tension specimen. Also a numerical technique which considers the growth of stress-free crack of concrete during the analysis and removes snapback of postpeak behavior is proposed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.519-521
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• 2015

세라믹 소재 영상에서 결함 영역이 다른 영역보다 명암도가 밝게 나타나는 정보를 이용하여 ROI 영역을 추출한다. 추출된 ROI 영역에서 Blurring 기법을 적용하여 미세 잡음을 제거한다. 미세 잡음이 제거된 ROI 영역에서 Median Filter기법을 적용하여 임펄스 잡음을 제거한다. 임펄스 잡음이 제거된 영역에서 Prewit Mask을 적용하여 수평과 수직 에지를 검출하고 검출된 에지에 윤곽선 추적 기법을 적용하여 결함 영역의 경계를 보정한다. 보정된 영상에서 Blob Labeling 기법을 적용하여 최종적으로 결함 영역을 추출한다. 제안된 방법을 8mm와 10mm 세라믹 소재 영상을 대상으로 실험한 결과, 기존의 결함 검출 방법보다 제안된 검출 방법의 검출 성능이 개선된 것을 확인하였다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.3
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• pp.188-197
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• 1999

In order to estimate the uranium flux from seawater to sediments, we took pore water samples and deployed benthic chambers on seafloor of Chonsu Bay, Korea. The uranium flux across the sediment-water interface was estimated from the pore water to be 0.112-0.566 mg/$m^2yr$, corresponding to a removal flux of $4.3-21.5{\times}10^7$ gU/yr for the entire Yellow Sea. Nutrient fluxes from sediment to bottom water were estimated to be 135.6 mmol/$m^2yr$ for ammonia, 228.2 mmol/$m^2yr$ for nitrate, 36.8 mmol/$m^2yr$ for phosphate and 23.9 mmol/$m^2yr$ for silicate. The redox boundary, based on the distribution of pore water nitrate and solid phase manganese, was located at 3-5 cm below the sediment surface. Phosphate flux obtained by benthic chambers was 28.S mmol/$m^2yr$. On the other hand, estimates of uranium and silicate fluxes were orders of magnitude greater than those based on pore water profiles. Flux estimates on the basis of pore water concentration is believed to have greater reliability than those obtained from benthic chamber data.