• 한국기계가공학회지
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• 제5권1호
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• pp.7-12
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• 2006

Recently, the fractal interpolation methods have been widely introduced and used to estimate and analyze various theoretical and experimental data. Because of the chaotic behaviors of dynamic cutting force data, some method for end-milling force analysis must be used. The fractal analysis used in this paper is fractal linear interpolation and fractal dimension. Also, several methods for computing fractal dimensions have been used in which the fractal dimension of the typical dynamic end-milling force was calculated according to number of data points that are generally lower than 200 data points sampled. This fractal analysis shows a possible prediction of end-milling force that has some dynamic chatter property or stationary property in endmilling operation.

• 한국공작기계학회논문집
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• 제15권3호
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• pp.67-72
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• 2006

There are many modelling methods using theoretical and experimental data. Recently, fractal interpolation methods have been widely used to estimate and analyze various data. Due to the chaotic nature of dynamic roundness profile data in roundness some desirable method must be used for the analysis which is natural to time series data. Fractal analysis used in this paper is within the scope of the fractal interpolation and fractal dimension. Also, two methods for computing the fractal dimension has been introduced which can obtain the dimension of typical dynamic roundness profile data according to the number of data points in which the fixed data are generally lower than 200 data points. This fractal analysis result shows a possible prediction of roundness profile that has some different roundness profile in round shape operation.

• 한국기계가공학회지
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• 제12권5호
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• pp.157-162
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• 2013

To analyze the dynamic acceleration characteristics, it is necessary to identify the acceleration model using some methods that can represent the dynamic properties well. In this sense, fractal methods were used for the verification of characteristics of an acceleration signal. To estimate and analyze the geometry of acceleration signal, a fractal interpolation and its analysis was introduced in this paper. The chaotic nature of acceleration signal was considered in fractal modeling. In this study the fractal signal modeling has brought a focus within the scope of the fractal interpolation and fractal dimension. And a new idea of fractal dimension has been introduced and discussed considering the damping ratio and amplitude for its dynamic properties of the signal. The fractal dimension of acceleration with respect to the scaling factor using fixed data points of 1000 points was calculated and discussed. The acceleration behaviors of this results show some different characteristics. And this fractal analysis can be applied to other signal analysis of several machining such as pendulum type grinding and milling which has many dynamic properties in the signal.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권12호
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• pp.5955-5977
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• 2018

Performance of the interpolation algorithm used in the technique of bi-dimensional empirical mode decomposition directly affects its popularization and application, so that the researchers pay more attention to the algorithm reasonable, accurate and fast. However, it has been a lack of an adaptive interpolation algorithm that is relatively satisfactory for the bi-dimensional empirical mode decomposition (BEMD) and is derived from the image characteristics. In view of this, this paper proposes an image interpolation algorithm based on the particle swarm and fractal. Its procedure includes: to analyze the given image by using the fractal brown function, to pick up the feature quantity from the image, and then to operate the adaptive image interpolation in terms of the obtained feature quantity. All parameters involved in the interpolation process are determined by using the particle swarm optimization algorithm. The presented interpolation algorithm can solve those problems of low efficiency and poor precision in the interpolation operation of bi-dimensional empirical mode decomposition and can also result in accurate and reliable bi-dimensional intrinsic modal functions with higher speed in the decomposition of the image. It lays the foundation for the further popularization and application of the bi-dimensional empirical mode decomposition algorithm.

• 대한의용생체공학회:의공학회지
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• 제17권1호
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• pp.121-128
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• 1996

본 논문은 심전도 데이터 압축을 위해 적응 프랙탈 보간(AFI)알고리듬 방법을 제안한다. 기존의 분할 프랙탈 보간(PFI) 알고리듬은 고정된 크기의 정의역 블럭을 사용한다. 따라서 그 재생오차가 원래의 심전도 신호의 특정 부분에 집중된다. 이 문제를 해결하기 위해 적응 프랙탈 보간 알고리듬에서는 가변 정의역 블럭을 사용한다. 만약 미리 정한 허용오차가 만족되지 않으면 정의역 블럭은 두개의 더 작은 정의역 블럭들로 나뉘어지게 된다. 큰 정의역 블럭들은 높은 압축 효율을 얻기 위해 굴곡이 적은 파형을 부호화 하는데 사용되고, 더 작은 정의역 블럭들은 신호의 질을 유지하기 위해 급격히 변화하는 파형을 부호화 하는데 사용된다. 제안된 알고리즘은 MIT/BIH 데이터베이스를 사용하여 평가되었다. AFI알고리듬은 주어진 압축률에서 기존의 PFI알고리듬보다 상대적으로 적은 재생 오차를 나타냈다. 약 7.13% 정도의 실효치 차이가 허용되는 응용에서, AFI알고리듬은 매개변수들에 대한 엔트로피 코딩 없이 10.51 이상의 압축률을 얻을 수 있었다.

• 전자공학회논문지B
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• 제33B권12호
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• pp.45-61
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• 1996

This paper presents the ECG data compression using wavelet transform (WT) and adaptive fractal interpolation (AFI). The WT has the subband coding scheme. The fractal compression method represents any range of ECG signal by fractal interpolation parameters. Specially, the AFI used the adaptive range sizes and got good performance for ECG data cmpression. In this algorithm, the AFI is applied into the low frequency part of WT. The MIT/BIH arhythmia data was used for evaluation. The compression rate using WT and AFI algorithm is better than the compression rate using AFI. The WT and AFI algorithm yields compression ratio as high as 21.0 wihtout any entropy coding.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 추계학술대회
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• pp.221-224
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• 1996

This paper presents the ECG data compression using wavelet transform(WT) and adaptive fractal interpolation(AFI). The WT has the subband coding scheme. The fractal compression method represents any range of ECG signal by fractal interpolation parameters. Specially, the AFI used the adaptive range sizes and got good performance for ECG data compression. In this algorithm, the AFI is applied into the low frequency part of WT. The MIT/BIH arrhythmia data was used for evaluation. The compression rate using WT and AFI algorithm is better than the compression rate using AFI. The WT and AFI algorithm yields compression ratio as high as 21.0 without any entroy coding.

• 대한의용생체공학회:의공학회지
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• 제16권1호
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• pp.17-24
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• 1995

본 논문은 iterated contractive transformations을 이용한 심전도 데이터 압축에 관한 새로운 방법을 제안한다. 이방법은 piecewise self-affine fractal interpolation(PSAFI)에 의해 심전도 신호의 임의 구간들을 표현한다. Piecewise self-affine fractal model은 자기자신의 수축적 유사 변환으로 구성된다고 볼 수 있는 이산 데이터에 사용된다. 제안된 알고리즘은 MIT/BIH arrhythmia 데이터베이스로 평가되었다. PSAFI는 주어진 압축율에서 기존의 직접 압축 방법보다 상대적으로 적은 재생 오차를 나타냈다. 샘플링 주파수는 400Hz이고 resolution은 12bits인 원래 신호에 대해 압축율이 883.9bps일때 평균재생오차(APRD)는 5.39%를 나타냈다.

• 전자공학회논문지B
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• 제33B권6호
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• pp.82-91
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• 1996

In this paper, an image coding technique using fractal interpolation is proposed. Similar to the conventional methods, an image is partitioned into blocks and each block is coded independently. However, an interpolation point is ahsared by its neighboring blocks. This means that each block can use all its interpolation points with minimal increase of new data. For a simple implementation, triangular blocks are used instead of square blocks and new coefficients are difined. Data obtained in the encoding process hav estatistical characteristics suitable sfor entropy coding, an dthus arithmetic coding is perfomred for improving the compression efficiency. The results of the proposed coder in comparison with those of a conventional coder show that the interpolation method reduces block effect caused by a memoryless block coder, especially at low bit rates. This improvement is due to sharing of information between adjacent blocks. Moreover, th enumber of iteration required in ecoding process is reduced since more information is used to decode each block.

• 한국수자원학회논문집
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• 제45권9호
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• pp.943-957
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• 2012

본 연구에서는 프랙탈 이론의 하천유역분야 적용성을 고찰을 통하여 하상의 불연속 경계면을 보간하기 위한 침식모형기반 프랙탈 기법을 제시하고, 이를 이용하여 적용 대상인 하상 경계부분의 3차원 지형을 생성하여 실제 측량성과와의 비교, 공간 통계학적 분석을 통해 이론의 적용성을 검증하였다. 침식모형기반 프랙탈 기법의 검증을 위해 표본을 추출하여 실제 지형측량결과 및 IDW 기법에 의한 보간 지형과의 분산분석을 수행하였다. 표본집단이 모집단과 동일 분산을 갖고 있는지에 대한 표고값 간의 F-검정 결과, 유의확률 0.501로 유의수준 0.05보다 큰 것으로 분석되어 표고의 표준차이는 없는 것으로 나타났다. 분산분석 결과 RMSE는 IDW 및 침식모형기반 프랙탈 기법 각 0.802, 0.384로 침식모형기반 프랙탈 기법이 우수한 것으로 나타났다. 이러한 결과로 부터 3차원 정밀 하상 지형 생성 방법으로 침식모형기반 프랙탈 기법의 적용성이 우수한 것으로 사료된다.