• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.1
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• pp.95-101
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• 2017

In natural images, there is generally locality, and the values of adjacent pixels are similar. It is possible to estimate the curved surface characteristics of the original image using adjacent pixels having similar pixel values. In this paper, after precisely estimating the characteristics of the curved surface existing in the image, interpolation values are obtained so as to faithfully reflect the estimated characteristics of the curved surface, We propose an effective image enlarging method that generates an enlarged image using the obtained interpolation values. The image enlarged by the proposed method maintains the curved surface characteristics of the original image, and thus the image quality of the enlarged image is improved. Experimental results show that the image quality of the proposed method is superior to that of the conventional techniques.

• Journal of the Korea Society of Computer and Information
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• v.19 no.8
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• pp.45-54
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• 2014

In this paper, we proposed an effective quality improvement scheme of magnified image using the surface characteristics in image. If the surface in image is estimated as simple convex surface or simple concave surface, the interpolated value can be calculated to have the surface characteristics by using the other method in the proposed scheme. The calculated value becomes the interpolated pixel value inmagnified image. So, themagnified image reflects the surface characteristics of the real image. If the surface is not estimated as simple convex surface or simple concave surface, the interpolated value is calculated more accurately than bilinear interpolation by using the method of the proposed scheme. The PSNR values of the magnified images using the proposed schemes are greater than those of the magnified images using the previous interpolation schemes.

• Journal of the Korea Computer Graphics Society
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• v.11 no.2
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• pp.47-55
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• 2005

곡면 복원이나 곡면 복원과 질은 관련이 있는 노말 추정을 하는 대부분의 방법은 결정론적인 알고리즘을 사용한다. 결정론적 알고리즘은 속도가 빠르고, 오차가 크지 않은 입력에 대해서는 좋은 질의 곡면 복원을 할 수 있다. 그러나 결정론적 방법의 특성상 이상치나 노이즈를 가진 데이터에 대해서는 안정된 복원 결과를 얻을 수 없다. 본 논문에서는 앙상블이라고 불리는 통계적인 방법을 사용해서 곡면 복원과 노말 추정을 하는 기존의 알고리즘을 개선한다. 앙상블 기법은 먼저 입력 점 집합을 무작위로 샘플링해서 점 집합의 부분집합을 만든다. 그리고 나서 만들어진 부분 집합에 독립적으로 결정론적인 알고리즘을 적용하여 결과를 얻어낸다. 마지막으로, 각각의 서로 다른 결과를 결합하여 더 우수한 최종결과를 얻어낸다. 널리 쓰이는 노말 추정 기법[11]과 Multi-level Partitions of Unity implicit [18]를 사용해서 앙상블이 효과적으로 노이즈가 많은 데이터를 처리할 수 있는 것을 보여준다.

• Journal of the Korea Society of Computer and Information
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• v.20 no.1
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• pp.63-73
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• 2015

In this paper, a quality improvement scheme is proposed for magnified image using the various curved surface characteristics of image. After testing horizontal and vertical directional surface characteristics of source image, interpolation value is calculated to have the surface characteristics such as simple convex surface, simple concave surface, and compound surface. The calculated interpolation value become the value of the interpolated pixel of magnified image. The calculated interpolation value is closer to the pixel value of real image. So, the quality of the magnified image is improved. The PSNR value of the magnified image using the proposed scheme is larger than the PSNR values of the magnified image using the existing techniques.

• Proceedings of the Korea Society for Simulation Conference
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• 2004.05a
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• pp.41-47
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• 2004

중심합성계획(central composite design: ccd)은 반응 표면이 곡면적인 특성을 나타낼때 반응 공간을 추정하기 위해 사용되는 실험계획이다. 반응공간이 2차 회귀모형으로 나타나는 경우에 반응곡면의 변화량을 알기 위해서는 변수의 수준이 3이상이 되어야하는데 ccd는 적은 횟수의 실험으로 곡면을 효과적으로 추정하기 위해 2$^{k}$ 요인실험에 추가적으로 중심점(central point)과 축점(axial point)을 표본점에 포함시키는 계획이다. 본 연구에서는 시뮬레이션 실험에서 반응변수가 2차 회귀모형으로 근사되는 경우에 cod를 이용하여 관심 성과치의 반응표면을 추정하고자 한다. 일반적인 실험에서와는 달리 시뮬레이션 실험에서는 두개의 표본점(인자 수준의 조합)에서 분석자가 공통 난수계열(common random number series)을 부여하여 시뮬레이션 시스템 요소의 변화과정을 유사하게 통제할 수 있다. 일반적으로 공통난수법(common random number method)에 의해 얻어지는 두 표본점에서의 반응변수는 서로 양의 상관관계를 가지며 대조 난수(antithetic random number)에 의한 두 반응변수는 음의 상관성을 가지는 것으로 알려졌다. 본 연구는 ccd의 표본점에 공통난수와 대조난수 법을 이용하여 회귀모형의 파라미터를 효과적으로 추정하는 방법을 조사하고 이를 (s, S) 재고관리 모형에 적용하여 그 효율성을 평가하고자 한다.

• Journal of the Korea Society of Computer and Information
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• v.18 no.11
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• pp.59-68
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• 2013

In this paper, an effective scheme was proposed to estimate simple convex surface and simple concave surface which exist in image. This scheme is applied to input image to estimate simple convex surface or simple concave surface. When simple convex surface or simple concave surface exists, another proposed efficient interpolation scheme is used for the interpolated pixel to have the characteristics of simple convex surface or simple concave surface. The magnified image using the proposed schemes is more similar to the real image than the magnified image using the previous schemes. The PSNR values of the magnified images using the proposed schemes are greater than those of the magnified images using the previous interpolation schemes.

• Journal of the Korea Society of Computer and Information
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• v.18 no.2
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• pp.49-57
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• 2013

To improve the quality of magnified image, two schemes were proposed. The one is used to estimate simple convex surface and simple concave surface using the information of adjacent pixel values, and the other scheme is used to produce magnified image using the characteristics of simple convex surface and simple concave surface. The magnified image using the proposed scheme is more similar to real image than the magnified image using the previous schemes. The PSNR values of the magnified images using the proposed scheme are greater than those of the magnified images using the previous interpolation schemes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.4
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• pp.53-66
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• 1990

Rainfall is a phenomenon that shows a high variability both in space and time, Hy drologists are usually interested in the description of spatial distribution of rainfall over watershed. The theory of Kriging, generalized covariance technique using nonstationary mean in the regions under orographic effect, was chosen to construct random surface of total storm depth. For the constructed random surface, the double Fourier analysis of the total storm depths was performed, and the principal harmonics of storm were determined. The local component, or storm residuals was obtained by subtracting the periodic component of the storm from total storm depths. It is assumed that the residuals are a sample function of a homogeneous random field. This random field can be characterized by an isotropic one dimensional autocorrelation function or its corresponding spectral density function. Under this assumption, this study proposed a theorectical model for spectral density function adapted to two watersheds.

• Journal of the Korea Society of Computer and Information
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• v.17 no.2
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• pp.59-67
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• 2012

In this paper, an efficient interpolation scheme using gradient information between adjacent pixel values was proposed to estimate the value of interpolated pixel to have the locality which exists in real image and the characteristic of simple convex surface and simple concave surface which exist partially in the real image. PSNR(Peak Signal to Noise Ratio) was used to evaluate the performance of the proposed scheme. The PSNR values of the magnified images using the proposed scheme are greater than those of the magnified images using the previous interpolation schemes.

• Korean Journal of Remote Sensing
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• v.28 no.5
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• pp.549-559
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• 2012

This paper presents a comparative analysis on the applicability of a priori statistic information about adjustment models when the surface shape parameters are estimated at an arbitrary point in an elevation data. Although the reliability of the estimates are known to be affected by surface condition and the adjustment models, there has been little research in a systematic and detail way. When the raw data have been taken from a real measurement, its true value cannot be known, however, thus this study used simulation data in order to analyze clearly the applicability of adjustment models. The generation of simulated data was performed by superimposing horizontal, slope, and curve surfaces and adding a certain amount of noise. Comparative analysis was performed by associating the a posteriori estimates with a priori statistics of each adjustment models. The experimental results show the estimation characteristics of adjustment models against varying surface conditions.