• Journal of the Korean Statistical Society
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• 제29권4호
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• pp.455-471
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• 2000

A new method is developed for estimating the mean of a population which has a linear trend. The proposed estimator is based on the balanced systematic sampling method and the concept of interpolation. The efficiency of the proposed method is compared with that of existing methods.

• 대한수학회논문집
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• 제17권4호
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• pp.731-740
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• 2002

We derive the generalized Hermite interpolation by using the contour integral and extend the generalized Hermite interpolation to obtain the sampling expansion involving derivatives for band-limited functions f, that is, f is an entire function satisfying the following growth condition ｜f(ｚ)｜$\leq$ A exp($\sigma$｜y｜) for some A, $\sigma$ > 0 and any ｚ=$\varkappa$ + iy∈C.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2000년도 하계종합학술대회논문집
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• pp.213-216
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• 2000

본 논문에서는 volume rendering 기법을 이용하여 2차원 MRI 영상들을 합성하여 3차원 영상 만들 때 보다 해상도를 높이기 위한 개선된 sampling방법을 소개한다 2차원 슬라이스 영상들이 3차원으로 재구성할 때 voxel 기반으로 렌더링을 하기 때문에 오브젝트의 내부 영역까지도 볼 수 있는 것이 volume rendering의 가장 큰 장점이다. 따라서 영상을 재구성하는 과정에서 보다 향상된 interpolation을 적용시켜서 공간 해상도를 향상시키면 보다 명확하게 오브젝트 내부 정보를 살펴 볼 수 있다. 본 논문에서는 nearest neighbor 이나 linear 같은 interpolation으로 sampling한 방법보다 cubic interpolation을 3차원 공간에서 적용 시켜서 보다 resampling이 잘 되도록 하여 해상도를 향상시켜 보았다. 이렇게 향상된 Interpolation 적용시켜서 렌더링할 때 얼마나 오브젝트 내부 영역이 잘 가시화가 되었는지 transfer function을 적용시켜서 오브젝트 내부 정보를 렌더링 해보았고, 임의의 축으로 오브젝트을 잘라서 2D 단면 영상으로 출력해 보았다. 보다 향상된 interpolation을 적용시켜서 resampling을 하면 영상 해상도가 개선되었음을 볼 수 있었다.

• 전기학회논문지
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• 제57권2호
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• pp.294-302
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• 2008

In this paper, we present a new image up-sampling method which registers low resolution images to the high resolution grid when Bayesian super-resolution image processing is performed. The proposed up-sampling method interpolates high-resolution pixels using high-frequency data lying in all the low resolution images, instead of up-sampling each low resolution image separately. The interpolation is based on B-spline non-uniform re-sampling, adjusted for the super-resolution image processing. The experimental results demonstrate the effects when different up-sampling methods generally used such as zero-padding or bilinear interpolation are applied to the super-resolution image reconstruction. Then, we show that the proposed hybird up-sampling method generates high-resolution images more accurately than conventional methods with quantitative and qualitative assess measures.

• 전기학회논문지
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• 제65권8호
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• pp.1418-1423
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• 2016

The purpose of this research is to investigate the effect of sampling frequency on the photoplethysmography (PPG) and to evaluate the performance of interpolation methods for under-sampled PPG. We generated down-sampled PPG using 10 kHz-sampled PPG then evaluated waveshape changes with correlation coefficient. Correlation coefficient was significantly decreased at 50 Hz or below sampling frequency. We interpolated the down-sampled PPG using four interpolation method-linear, nearest, cubic spline and piecewise cubic Hermitt interpolation polynomial - then evaluated interpolation performance. As a result, it was shown that PPG waveform that was sampled over 20 Hz could be reconstructed by interpolation. Among interpolation methods, cubic spline interpolation showed the highest performance. However, every interpolation method has no or less effect on 5 Hz sampled PPG.

• Communications for Statistical Applications and Methods
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• 제9권1호
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• pp.175-185
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• 2002

A method is proposed for efficiently estimating the mean of a population which has a linear trend. The proposed estimator is based on the centered modified systematic sampling method and the concept of interpolation. Using the expected mean square error criterion, it is shown that the proposed method is more efficient than conventional methods in most real cases.

• Journal of the Korean Data and Information Science Society
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• 제10권1호
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• pp.91-102
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• 1999

A new method is developed for estimating the mean of a population which has a linear trend. The suggested estimator is based on the balanced systematic sampling method and the concept of interpolation and extrapolation. The efficiency of the proposed method is compared with that of conventional methods.

• 한국데이터정보과학회:학술대회논문집
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• 한국데이터정보과학회 2001년도 추계학술대회
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• pp.17-24
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• 2001

A method is proposed for efficiently estimating the mean of a population which has a linear trend. The proposed estimator is based on the centered modified systematic sampling method and the concept or interpolation. Using the expected mean square error criterion, it is shown that the proposed method is more efficient than conventional methods in most real cases.

• 한국멀티미디어학회논문지
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• 제5권5호
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• pp.494-504
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• 2002

볼륨랜더링은 연속적인 2차원 영상들을 기반으로 하여 3차원 데이터로 만드는 것이다. 오브젝트의 내부영역까지도 가시화 할 수 있는 장점 때문에, 최근 MRI, PET, SPECT같은 의료 영상의 경우 볼릅랜더링을 이용해서 진단에 많이 사용하고 있다. 본 논문에서는 볼륨랜더링을 쉽게 할 수 있도록 2차원 데이터를 바탕으로 볼륨데이터를 만드는 방법을 제시하고, 볼륨랜더링 기법을 이용해 의료 영상에 적용시켜 보았다. 또한 2차원 데이터를 추출하는 샘플링 단계에서 해상도를 향상시키기 위해 linear interpolation과 cubic interpolation을 통해 볼륨랜더링된 영상의 공간 해상도를 조절하도록 설계 및 구현하여 보았으며, 변형함수(transfer function)를 이용하여 각각의 결과를 비교하였다 2차원 영상의 샘플링에 사용되는 interpolation 방법을 3차원 영상에 적용하여 구현하였다. 의료영상의 볼륨랜더링 기법은 3차원 입체 데이터로 구현되는 것이므로 영상 분석을 통한 진단에 크게 기여 할 것으로 기대된다.

• 한국의학물리학회지:의학물리
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• 제27권3호
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• pp.105-110
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• 2016

Sparse angular sampling has been studied recently owing to its potential to decrease the radiation exposure from computed tomography (CT). In this study, we investigated the analytic reconstruction algorithm in sparse angular sampling using the sinogram interpolation method for improving image quality and computation speed. A prototype of the spectral CT system, which has a 64-pixel Cadmium Zinc Telluride (CZT)-based photon-counting detector, was used. The source-to-detector distance and the source-to-center of rotation distance were 1,200 and 1,015 mm, respectively. Two energy bins (23~33 keV and 34~44 keV) were set to obtain two reconstruction images. We used a PMMA phantom with height and radius of 50.0 mm and 17.5 mm, respectively. The phantom contained iodine, gadolinium, calcification, and lipid. The Feld-kamp-Davis-Kress (FDK) with the sinogram interpolation method and Maximum Likelihood Expectation Maximization (MLEM) algorithm were used to reconstruct the images. We evaluated the signal-to-noise ratio (SNR) of the materials. The SNRs of iodine, calcification, and liquid lipid were increased by 167.03%, 157.93%, and 41.77%, respectively, with the 23~33 keV energy bin using the sinogram interpolation method. The SNRs of iodine, calcification, and liquid state lipid were also increased by 107.01%, 13.58%, and 27.39%, respectively, with the 34~44 keV energy bin using the sinogram interpolation method. Although the FDK algorithm with the sinogram interpolation did not produce better results than the MLEM algorithm, it did result in comparable image quality to that of the MLEM algorithm. We believe that the sinogram interpolation method can be applied in various reconstruction studies using the analytic reconstruction algorithm. Therefore, the sinogram interpolation method can improve the image quality in sparse-angular sampling and be applied to CT applications.