• Journal of information and communication convergence engineering
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• 제9권3호
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• pp.271-275
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• 2011

In this paper, we present a hybrid encryption for a digital hologram which is the most valuable image content. The encryption algorithm is based on a hybrid technique implementation a four-dimensional transform combining the discrete wavelet transform(DWT) and the discrete cosine transform (DCT). The encryption scheme is composed on the basis of the energy distribution. The experimental results showed that encrypting only 0.0244% of the entire data was enough to hide the constants of the hologram. The encryption algorithm expected to be used effectively on the researches on encryption and others for digital holographic display.

• 한국해양공학회지
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• 제6권2호
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• pp.133-142
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• 1992

Beach evolution is of the most important problem is the coastal engineering. Especially, the structure construction through reclamation in the shallow water region nesar the beach will cause many severe problems around the structure. Beach evolution due to the construction of an artificial island in this study was studied using wave transform model and associated of an artificial island in this study was studied using wave transform model and associated sediment transport model. Numerical simulation of the model was applied to the Kwangan beach using the data of waves and shoreline of the area. The combined wave transform model and beach evolution model showed good results. The results show a breakwater will be needed to prevent severe erosion near the eastward Kwangan beach when construction an artificial island in the Suyong Bay. Good results of the study also suggest that the present model can be more widely applied to the prediction of beach evolution.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권11호
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• pp.780-785
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• 2004

In this paper, we proposed a ventricular fibrillation detection algorithm based on wavelet transform and artificial neural network. we selected RR intervals, the 6th and 7th wavelet coefficients(D6, D7) as features for classifying ventricular fibrillation. To evaluate the performance of the proposed algorithm, we compared the result of the proposed algorithm with that of fuzzy inference and fuzzy-neural network. MIT-BIH Arrhythmia database, Creighton University Ventricular Tachyarrhythmia database and MIH-BIH Malignant Ventricular Arrhythmia database were used as test and learning data. Among the algorithms, the proposed algorithm showed that the classification rate of normal and abnormal beat was sensitivity(%) of 96.10 and predictive positive value(%) of 99.07, and that of ventricular fibrillation was sensitivity(%) of 99.45. Finally. the proposed algorithm showed good performance compared to two other methods.

• 응용통계연구
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• 제13권2호
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• pp.525-540
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• 2000

본 논문에서는 측우기 관측자료와 현대 관측자료로 이루어진 서울 강수량 시계열 자료에 나타난 시간에 따른(년도별 및 계절별)변화 및 변동 특성을 파악하고자 한다. 이를 위하여 먼저 200여년 간의 강수량 시계열에 어떤 특정한 증감 추세가 있는지를 알아보는 추세분석을 실시하였다. 그리고 추세뿐만 아니라 시간에 따른 강수량의 주기성 및 변동성을 더 자세히 알기 위하여 파엽 변환(wavelet transform)을 실시하여 여러 진동 모드들의 시간에 따른 변화 양상을 분석하였다.

• 대한전자공학회논문지
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• 제26권11호
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• pp.1880-1885
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• 1989

In this paper, a new approach for systolic array realizing the discrete cosine transform (DCT) based on discrete Fourier transform (DFT) of an input sequence is presented. The proposed array is based on a simple modified DFT(MDFT) version of the Goertzel algorithm combined with Kung's approach and is proved perfectly. This array requires N cells, one multiplier and takes N clock cycles to produce a complete N-point DCT and also is able to process a continuous stream of data sequences. We have analyzed the output signal-to-noise ratio(SNR) and designed the circuit level layout of one-PE chip. The array coefficients are static adn thus stored-product ROM's can be used in place of multipliers to limit cost as eliminate errors due to coefficients quantization.

• 한국정보통신학회논문지
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• 제6권8호
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• pp.1139-1145
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• 2002

웨이브렛 변환 데이터는 신호의 상세 정보를 포함하고 있으므로 주파수 대역별로 필터링할 수 있다. 따라서, 본 논문에서는 중요한 두 가지 잡음을 웨이브렛을 사용하여 제거하였다. AWGN 환경에 대해서 hard-threshold를 적용한 UDWT(undecimated discrete wavelet transform)를 사용하였으며, 임펄스 잡음환경에 대해서는 임계치에 의한 잡음 제거와 웨이브렛에 의한 신호의 slope를 이용하여, 잡음 제거 효과를 최대로 함과 동시에 원신호의 edge를 인식하도록 하였다. 이러한 잡음 제거 효과의 판단 기준으로 SNR을 사용하였으며, 테스트 신호로서 Blocks와 DTMF(dual tone multi frequency)를 사용하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.459-460
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• 2001

In this paper, we analyze algorithms for diagnosing of VEP(visual evoked potential) signal. We used wavelet transform for the preprocessing of VEP signal data and back propagation neural network for the pattern recognition. We used several wavelets to study their effects and efficiency in the preprocessing of VEP. The diagnosis system led to good results. We obtained the noise reduced and compressed signal with the wavelet transform of the training VEP signal. So it is possible to train the neural network faster and exact diagnosis processing is possible in the neural network. From the experimental results, we know that the discrimination ability of the neural network is changed by the type of basis vector and the proposed system is good to the diagnosis of VEP.

• 대한전자공학회논문지
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• 제25권7호
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• pp.851-858
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• 1988

In this paper, we propose two different VLSI architectures for the parallel computation of DCT (discrete cosine transform) algorithm. First, it is shown that the DCT algorithm can be implemented on the existing systolic architecture for the DFT(discrete fourier transform) by introducing some modification. Secondly, a new prime factor DCT algorithm based on the prime factor DFT algorithm is proposed. And it is shown that the proposed algorihtm can be implemented in parallel on the systolic architecture for the prime factor DFT. However, proposed algorithm is only applicable to the data length which can be decomposed into relatively prime and odd numbers. It is also found that the proposed systolic architecture requires less multipliers than the structures implementing FDCT(fast DCT) algorithms directly.

• ETRI Journal
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• 제23권2호
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• pp.85-95
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• 2001

The surface modeling capability of CAD systems is widely used to design products bounded by free form surfaces and curves. However, the surfaces or curves generated by popular data fitting methods usually have shape imperfections such as wiggles. Thus, fairing operations are required to remove the wiggles, which makes the surfaces or curves smooth. This paper proposes a new method based on the wavelet transform for fairing the surfaces or curves while preserving the continuity with adjacent surfaces or curves. The wavelet transform gives a hierarchical perspective of the surfaces and the curves, which can be decomposed into the overall sweep and details, i.e., local deviations from sweep like the wiggles. The proposed fairing method provides a similar effect on the mathematical surface as that of the grinding operation using sandpaper on the physical surface.

• 제어로봇시스템학회논문지
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• 제4권4호
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• pp.517-524
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• 1998

This paper discusses the development of a reactive power controller using digital signal processing. Digital Signal Processing is the technique of using digital devices to Process continuous signals or data, often in real-time. And DSP algorithms are associated with a discrete time interval between input samples. When one designs a digital filter, one can use a Laplace transform to determine the continuous time frequency response. The corresponding discrete time transform is called Z transform and depends upon discrete samples of the input spaced equally in time. The objectives of this paper are to minimize real power losses and improve the power factor of a given system. Also, the implementation of a direct-form non recursive filter on the TMS320C31 has been described. The application of this microprocessor-based controller using DSP on test system reveals its numerous advantages. Performance and features of the controller for the reactive power control are analyzed.