• The Journal of the Korea Contents Association
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• v.6 no.10
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• pp.107-113
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• 2006

Error Concealment method for Intra frames in H.264 reconstructs the lost block by computing weighted average value of the boundary pixels of the neighboring blocks; up, bottom, left and right blocks. However a simple average of pixel values of the neighboring blocks for Intra frames in H.264 leads to excessive blurring and degrades the picture quality severely. To solve this problem, in this paper we estimate the dominant edge of lost block using the pixel values of the neighboring blocks and reconstruct the pixel values by choosing adaptive interpolation between directional interpolation and weighted average interpolation considering the result value of the interference function based on statistics. Finally directional interpolation method improves by determining the dominant edge direction considering the relation of the dominent edge and the edges of neighboring blocks. Experiments show improvement of picture quality of about $0.5{\sim}2.0dB$ compared with the method of H.264.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.205-208
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• 2008

In numerical analysis numerical values of thermodynamic properties such as temperature, pressure, specific volume, enthalpy and entropy are required. But most of the thermodynamic properties of the steam table are determined by experiment. Therefore they are supposed to have measurement errors. In order to make noised thermodynamic properties corresponding to errors, random numbers are generated, adjusted to appropriate magnitudes and added to original thermodynamic properties. the neural networks and quadratic spline interpolation method are introduced for function approximation of these modified thermodynamic properties in the saturated water based on pressure. It was proved that the neural networks give smaller percentage error compared with quadratic spline interpolation. From this fact it was confirmed that the neural networks trace the original values of thermodynamic properties better than the quadratic interpolation method.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.1
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• pp.17-25
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• 2007

In most electronic imaging applications, image with high resolution(HR) are desired. HR means that pixel density within an image is high, and therefore HR image can offer more details that may be critical in various applications. Digital images that are captured by CCD and CMOS cameras usually have a very low resolution, which significantly limits the performance of image recognition systems. Image super-resolution techniques can be applied to overcome the limits of these imaging systems. Super-resolution techniques have been proposed to increase the resolution by combining information from multiple images. To techniques were consisted of the registration algorithm for estimation and shift, the nearest neighbor interpolation using weight of acquired frames and presented frames. In this paper, it is proposed the image interpolation techniques using the wavelet base function. This is applied to embody a correct edge image and natural image when expend part of the still image by applying the wavelet base function coefficient to the conventional Super-Resolution interpolation method. And the proposal algorithm in this paper is confirmed to improve the image applying the nearest neighbor interpolation algorithm, bilinear interpolation algorithm.,bicubic interpolation algorithm through the computer simulation.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1998.12a
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• pp.527-536
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• 1998

블록암호의 설계에서 S-box는 가장 중요한 요소이다. S-box의 크기는 기존공격에 대한 안전도와 수행 시 필요한 메모리량, 수행속도가 동시에 고려되어 선택되어야 한다. 일반적으로 S-box의 입출력의 크기가 커지면 안전도와 메모리 소요량은 크게 증가하며 수행속도는 저하된다. 한편, GF(2$^{n}$ )에서의 멱함수(power permutation)는 DC, LC에 강하므로 여러 암호에 적용되었으나 최근 고계차분공격(higher order differential attack)과 보간공격 (interpolation attack)에 의해 공격된 바 있다. 본문에서는 DC, LC, 고계차분공격, 보간공격에 안전한 S-box로서 GF(2$^{n}$ )에서의 멱함수인 $\chi$$^{-2}$ $^{k}$ (k < n)를 구성하고, n이 짝수일 때 메모리 소요량이 보다 적은 구현방법으로서 GF(2$^{n}$ 2/)의 연산을 이용하는 방법을 제시한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.12
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• pp.3003-3009
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• 2000

In this paper, we propose a new efficient hybrid-mixed C(sup)0 curved beam element with the optimal interpolation functions determined from numerical tests, which gives very accurate locking-free two-node curved beam element. In the element level, the stress parameters are eliminated from the stationary condition and the nodeless degrees of freedom are also removed by static condensation so that a standard six-by-six stiffness matrix is finally obtained. The numeri cal benchmark problems show that the element with cubic displacement functions and quadratic stress functions is the most efficient.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10a
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• pp.109-112
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• 2001

실세계의 움직이는 여러 이동객체들은 시공간적인 특성을 지니고 있다. 이들 객체는 실세계의 공간 즉, 점들의 집합 내에 위치해 있으며 이들을 데이터베이스로 표현 및 관리하기 위해서는 점 흑은 영역 형태로 표현하고 저장하게 된다. 이 논문에서는 샘플링되지 않은 시점에 대한 이동객체의 위치 질의시 발생할 수 있는 이동객체의 불확실성을 처리하는 데 있어서, 기존의 선형 보간법 대신 이동객체의 위치값 자체의 오차범위까지 고려하는 다항회함수(polynomial regression function)을 이용한 이동객체의 불확실한 이동위치 추정 방법을 제시하였으며, 이동객체의 이동경로를 구현하였다. 다항회귀모형을 이용할 경우 선형 보간법 보다 추정된 위치간에 대한 오차를 줄일 수 있으며, 이동객체의 과거 및 미래 위치값을 사용자에게 반환해 줄 수 있는 장점을 가진다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.3 s.73
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• pp.223-231
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• 2006

This study deals with behavior characteristics of laminated composite folded structures according to ratio of folded length based on a higher-order shear deformation theory. Well-known mixed finite element method using Lagrangian and Hermite shape interpolation functions is a little complex and have some difficulties applying to a triangular element. However, a higher-order shear deformation theory using only Lagrangian shape interpolation functions avoids those problems. In this paper, a drilling degree of freedom is appended for more accurate analysis and computational simplicity of folded plates. There are ten degrees of freedom per node, and four nodes per element. Journal on folded plates for effects of length variations is not expressed. Many results in this study are carried out according to ratio of folded length. The rational design is possible through analyses of complex and unpredictable laminated composite folded structures.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.7 no.2
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• pp.53-61
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• 1989

In this paper the quantitative classification parameters of terrain which can be practicable to the interpolation of digital terrain model forming a regular grid pattern have been suggested and objective terrain classification have been established by making a cluster analysis using these parameters. Also, interpolation suitable to the classification of terrain has been used by making a descriminant alaysis from description parameters of terrains. The terrain classification in this paper was dependent upon two parameters of the ratio horizontal area to inclined area and the magnitude of harmonic vectors. And the studying area was seperated to three groups of terrains by these two parameters. Three groups of terrains could be classified into the discriminant functions. By determining the ratio of area and harmonic vector magnitude in any terrains using the above discriminant function, it was possible to discriminate the terrains to apply the interpolation practicable to the terrain characteristics.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.331-332
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• 2011

본 논문에서는 Markov random field (MRF) 프레임워크와 영상의 기울기(gradient) 정보를 이용한 필드영상의 공간적 디인터레이싱(deinterlacing) 알고리즘을 제안한다. 기존의 디인터레이싱 결과를 보면 때때로 에지 부분의 연결이 정밀하지 못하여 눈에 거슬리는 재깅(jagging) 현상 등의 결함이 나타나기도 하는데, 제안하는 알고리즘은 이러한 현상을 줄이고자 영상의 기울기 도메인(gradient domain)에서 디인터레이싱을 수행한다. 즉, 제안하는 방식은 필드 영상으로부터 기울기 영상을 얻고 이를 보간한 후 필드영상과 복원된 기울기 영상을 토대로 원본 영상을 복원한다. 이 과정에서 각각의 픽셀마다 기울기 영상의 보간을 위한 에지 방향의 추정이 필요한데, 이 과정에서는 MRF 모델을 기반으로 에너지 함수를 설계하고 최적화시킴으로써 보다 강건한 추정결과를 얻도록 하였다. 프레임 영상 복원은 기울기 영상과 필드 영상 정보를 사전 정보로 하여 선형 방정식을 세우고 푸는 과정으로 이루어진다. 실험한 결과, 제안된 방법의 결과가 기존 방법에 비하여 눈에 띄는 결함을 줄이고 좋은 성능을 보임을 확인할 수 있다.

• Journal of Korean Association for Spatial Structures
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• v.12 no.1
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• pp.109-119
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• 2012

For membrane structure, there are three main steps in design and construction, which are form finding, statistical load analysis, and cutting patterning. Unlike the first two stages, the step of cutting pattern involves the translation of a double-curved surface in 3D space into a 2D plane with minimal error. For economic reasons, the seam lines of generated cutting patterns rely greatly on the geodesic line. Generally, as searching regions of the seam line are plane elements in the step of shape analysis, the seam line is not a smooth curve, but an irregularly divided straight line. So, it is how we make an irregularly divided straight line a smooth curve that defines the quality of the pattern. Accordingly, in this paper, we analyzed interpolation schemes using spline, and apply these methods to cutting pattern generation on the curved surface. To generate the pattern, three types of spline functions were used, i.e., cubic spline function, B-spline, and least-square spline approximation, and simple model and the catenary-shaped membrane was adopted to examine the result of generation. The result of comparing the approximation curves by the number of elements and the number of extracted nodes of simple model revealed that the seam line for less number of extracted nodes with large number of elements were more efficient, and the least-square spline approximation provided smoother seam line than other methods.