• Journal of Korea Water Resources Association
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• v.47 no.10
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• pp.959-972
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• 2014

In this study, a space-time rainfall grid field generation model based on multifractal theory was verified using nine flood events in the upstream watershed of Chungju dam in South Korea. For this purpose, KMA radar rainfall data sets were analyzed for the space-time multifractal characteristics. Simulated rainfall fields that represent the multifractal characteristics of observed rainfall field were reproduced using the space-time rainfall grid field generation model with log-Poisson distribution and three-dimension wavelet function. Simulated rainfall fields were applied to the S-RAT model as input data and compared with both observed rainfall fields and low-resolution rainfall field runoff. Error analyses using RMSE, RRMSE, MAE, SS, NPE and PTE indicated that the peak discharge increases about 20.03% and the time to peak decreases about 0.81%.

• Journal of Korea Water Resources Association
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• v.47 no.9
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• pp.839-852
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• 2014

This study analyzed the applicability of a rainfall downscaling algorithm in space-time multifractal framework (RDSTMF) in Korean Peninsula. To achieve this purpose, the 8 heavy rainfall events that occurred in Korea during the period between 2008 and 2012 were analyzed using the radar rainfall imagery. The result of the analysis indicated that there is a strong tendency of the multifractality for all 8 heavy rainfall events. Based on the multifractal exponents obtained from the analysis, the parameters of the RDSTMF were obtained and the relationship between the average intensity of the rainfall events and the parameters of the RDSTMF was developed. Based on this relationship, the synthetic space-time rainfall fields were generated using the RDSTMF. Then, the generated synthetic space-time rainfall fields were compared to the observation. The result of the comparison indicated that the RDSTMF can accurately reproduce the multifractal exponents of the observed rainfall field up to 3rd order and the cumulative density function of the observed space-time rainfall field with a reasoable accuracy.

• Journal of Korea Multimedia Society
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• v.4 no.4
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• pp.234-332
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• 2001

For a method improving fractal image segmentation which is a new application of fractal image coding, YST scheme have proposed an image segmentation scheme using labeling based on periodic points of pixel transformation and error-correction of labels by iterating fractal transformation. The scheme generates the high quality segmentation, however, it has the redundancy in the process of labeling and correction of labels. To solve this problem, we propose a labeling algorithm based on orbit of pixel transformation and restricted condition on iterating process of fractal transformation.

• Proceedings of the Korea Multimedia Society Conference
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• 1998.04a
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• pp.116-121
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• 1998

본 논문에서는 데이터의존성과 벡터왜곡척도를 이용하여 개선된 칼라영상을 복호화하였다. 프랙탈 칼라영상의 복원방법은 Zhang과 Po의 벡터왜곡척도를 이용한 R, G, B 칼라 성분간의 상관관계를 고려하여 부호화한 압축파일을 사용하여 수렴될 복원영상을 독립적인 반복변환에 의해 수렴되는 영역과 데이터의존성을 갖는 영역으로 분류하여 데이터의존성 부분이 차지하는 만큼 복호화 과정에서 불필요한 계산량이 제거되었고, R 영역에서 검색한 데이터 의존영역을 G, B 영역에 그대로 사용하여 고속복호화가 가능하였다.

• Journal of Korea Multimedia Society
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• v.6 no.1
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• pp.89-96
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• 2003

This paper propose the new method witch is adopted in extracting character features and recognizing numeric characters using fractal dimension and modified Henon Attractor of the Chaos Theory. Firstly, it gets features of mesh feature, projection feature and cross distance feature from numeric character images And their feature hi converted into time series data. Then using the modified Henon system suggested in this paper, it gets last features of numeric character image after calculating Natural Measure and information bit which art meant fractal dimension. Finally, numeric character recognition is performed by statistically finding out the each information bit showing the minimum difference against the normalized pattern database. An Experimental result shows 100% character classification rates for 10 digits and 90% of recognition rates in real situation and the recognition speed was 26 characters per second.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.11b
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• pp.114-117
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• 2002

본 논문에서는 미세한 차이를 식별할 수 있는 Chaos 이론을 숫자 패턴 인식 분야에 응용한다. 먼저, 숫자 영상의 특징 정보들을 시계열 데이터로 변환한 후, 제안된 수정된 에농 시스템으로부터 숫자 어트랙터를 재구성하고, 어트랙터의 특성 분석을 위해 프랙탈 차원 특징을 나타내는 정보 차원값을 이용하여 숫자를 인식하는 새로운 알고리즘을 제안함으로써, 특수한 용도로 숫자를 전문적으로 빠르고 정확하게 인식하는 고정도 숫자 인식 시스템을 구현하였다.

• Journal of Korea Multimedia Society
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• v.2 no.1
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• pp.38-46
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• 1999

In this paper, the fractal image compression using the minimizing method of domain region is proposed. It is minimize to domain regions in the process of decoding. Since the conventional fractal decoding applies to IFS(iterative function system) for the total range blocks of the decoded image, its computational complexity is a vast amount. In order to improve this using the number of the referenced times to the domain blocks for the each range blocks, a classification method which divides necessary and unnecessary regions for IFS is suggested. If necessary regions for IFS are reduced, the computational complexity is reduced. The proposed method is to define the minimum domain region that a necessary region for IFS is minimized in the encoding algorithms. That is, a searched region of the domain is limited to the range regions that is similar with the domain regions. So, the domain region is more overlapped. Therefore, there is not influence on image quality or PSNR(peak signal-to-noise ratio). And it can be a fast decoding by reduce the computational complexity for IFS in fractal image decoding.

• Journal of Korea Multimedia Society
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• v.13 no.2
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• pp.298-307
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• 2010

The grass is one of important components that cover the wide surfaces in the application such as game or real time simulation. Actually, it not easy to render effectively numerous grasses that grow over the wide terrain. To solve the difficulty, we must find a solution to the two contradictions in terms : quality and calculation cost. As a solution to the above-mentioned task, in this paper, we propose an efficient method to represent the natural grasses by introducing fractal theory and instancing technique. Although the existing grass representation methods make use of a simple rule of applying a basic grass model repeatedly in rendering process, on the contrary we take advantage of the basic property of fractal's self-similarity and we devise a natural representation method suited to the given environment by introducing two important growth factors such as nature of terrain and quantity of light, and finally we apply a GPU-based shader instancing technique to rendering numerous grass models in real-time.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2
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• pp.365-372
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• 2000

he paper introduces evolutionary computing to Fractal Image Compression(FIC). In Fractal Image Compression(FIC) a partitioning of the image into ranges is required. As a solution to this problem there is a propose that evolution computation should be applied in image partitionings. Here ranges are connected sets of small square image blocks. Populations consist of $N_p$ configurations, each of which is a partitioning with a fractal code. In the evolution each configuration produces $\sigma$ children who inherit their parent partitionings except for two random neighboring ranges which are merged. From the offspring the best ones are selected for the next generation population based on a fitness criterion Collage Theorem. As the optimum image includes duplication in image data, it gets smaller in saving space more efficient in speed and more capable in image quality than any other technique in which other coding is used. Fractal Image Compression(FIC) using evolution computation in multimedia image processing applies to such fields as recovery of image and animation which needs a high-quality image and a high image-compression ratio.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.378-383
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• 2001

Intranet 환경에 다수의 유휴 호스트를 이용하여 많은 계산량을 지닌 응용 문제를 분산시켜 병렬 수행함으로써 효율성의 향상이 기대된다. 하지만 유휴 호스트를 이용하는데 있어서 이질성과 가변성 및 자율성으로 인해 요청에 대한 신뢰성을 예측하기가 어렵다. 본 논문에서는 태스크 할당 및 호스트 관리에 있어서 부하 균등을 위한 동적 분산 병렬 스킴인 적응적 태스크 재할당 기법을 제시한다. 또한, 이미지 랜더링 생성과 프랙탈 이미지 처리와 같은 많은 연산량을 지닌 응용 문제를 PDSWeb 시스템에 적용하여 제안 알고리즘의 성능을 분석하고 평가한다.