• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(4)
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• pp.179-182
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• 2002

In this paper, we propose a wavelet based adaptive algorithm which improves the convergence speed and reduces computational complexity using the fast running FIR filtering efficiently We compared the performance of the proposed algorithm with time and frequence domain adaptive algorithm using computer simulation of adaptive noise canceler based on synthesis speech. As the result, the proposed algorithm is suitable for adaptive signal processing area using speech or acoustic field.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(4)
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• pp.243-246
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• 2002

The proliferation of digitized media(audio, image and video) is creating a processing need for copyright enforcement schemes that protect copyright ownership. we argue that a watermark must be placed in perceptually significant components of a signal if it is to be robust to signal distortions and malicious attack. In this paper, RGB coordinate image is transformed into LUV coordinate, it include the characteristics of, Human vision and then the UV component is transformed into NxN block DCT transform. we propose a technique for embedding the watermark of visually recognizable mark into the middle frequency domain of image.

• Journal of Information Processing Systems
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• 제13권2호
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• pp.340-347
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• 2017

A watermark is a signal added to the original signal in order to preserve the copyright of the owner of the digital content. The basic challenge for designing a watermarking system is a dilemma between transparency and robustness. If we want a higher rate of transparency, there has to be a compromise in terms of its robustness and vice versa. Also, until now, watermarking is generalized, resulting in the need for a specialized algorithm to work for a specialized image processing application domain. Our proposed technique takes into consideration the image characteristics for watermark insertion and it optimizes transparency and robustness. It achieved a 99.98% retrieval efficiency for an image blurring attack and counterfeits other attacks. Our proposed technique counterfeits almost all of the image processing attacks.

• 조명전기설비학회논문지
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• 제21권3호
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• pp.75-81
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• 2007

Wavelet 변환은 신호를 분석하고 해석하는데 효과적인 수학적 도구로 알려져 여러 응용분야에서 다양한 연구가 진행되고 있다. Wavelet 변환은 Fourier 변환과 유사한 측면도 있으나, Fourier 변환과는 달리 다양한 Wavelet 모함수를 사용함으로써 해석 속도가 빠르고, 시간-주파수 영역에서 국재화가 가능하다는 특징을 가지고 있을뿐만 아니라 고주파 성분에 대해선 시간 분해능이 높고, 저주파 성분에 대해선 주파수 분해능이 좋다는 장점을 가지고 있으므로, 전력계통의 다양한 고장 전류의 판별에 적극 이용할 수 있을 것으로 생각된다. 본 논문에서는 고장 전류의 특성을 해석하는데 용이한 복소형의 Morlet Wavelet 모함수를 사용하여 전력계통의 고장기록장치로부터 얻어지는 선로의 전류 데이터를 Wavelet 변환하였고, 이로부터 다양한 고장 모드를 판별할 수 있었다. 실험 결과 Wavelet 변환을 이용하여 선로의 고장 모드를 판별하는 것이 기존의 고속 Fourier 변환을 이용하는 것보다 특징점 고찰에 더욱 유용하다는 것을 확인할 수 있었다.

• 한국터널지하공간학회 논문집
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• 제5권1호
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• pp.13-21
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• 2003

콘크리트 라이닝의 안정성을 검토하기 위해 지난 수년간 많은 연구가 이루어졌으며, 많은 비파괴 조사 기법들이 개발되고 발전하였다. 이러한 비파괴 조사 기법들은 그 신호 해석 과정에서 대부분 푸리에 이론을 근간으로 하고 있다. 그러나 진동신호에 대하여 푸리에 해석을 적용할 경우 결과는 단지 주파수 영역상에서 확인될 뿐이며, 이러한 결과로는 정확한 대상 신호의 분석을 기대할 수 없다. 따라서 본 연구에서는 충격하중으로 인하여 발생한 비정상 파의 해석을 위하여 웨이블릿 이론을 적용하였으며, 웨이블릿 변환의 적용성을 확인하기 위하여 콘크리트 라이닝을 모사한 모형을 대상으로 실험을 수행하고, 제안된 이론을 바탕으로 콘크리트 라이닝의 두께를 추정하였다. 본 연구로부터 푸리에 변환에 비해 웨이블릿 변환이 뛰어난 분해능을 제공함을 확인할 수 있었으며, 분산성을 갖는 파를 해석함에 있어서도 웨이블릿 변환이 뛰어난 신호 해석법임을 확인할 수 있었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.277-280
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• 2002

Many digital watermarking methods have been proposed for copyright protection. Especially, methods to add a watermark in the frequency domain are often used. In those methods, only a few components of frequencies are changed according to watermark information, so that the pixel values of the image obtained by the inverse transform sometimes exceed the dynamic range and owing to the clipping process at this time watermark information is changed. This phenomenon even occurs without attacks like image processing. In this paper, we propose two methods to prevent loss of watermark information, applicable to such cases, it is said that one is the method called "inversion of increase and decrease" and another is "conservation of amounts of changes." We can extract the watermark information correctly under the condition of no attacks by using these proposed methods.

• IEIE Transactions on Smart Processing and Computing
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• 제4권1호
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• pp.22-27
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• 2015

Transform-domain JND (Just Noticeable Difference)-based for PVC (Perceptual Video Coding) is often performed in quantization processes to effectively remove perceptual redundancy. This study examined the JND-suppression effects on quantized coefficients of transform in HEVC (High Efficiency Video Coding). To reveal the JND-suppression effect in quantization, the properties of the floor functions were used for modeling the quantized coefficients, and a JND-adjustment process in an HEVC-compliant PVC scheme was used to tune the JND values by analyzing the JND suppression effect. In the experimental results, the bitrate reduction decreases slightly, but the PSNR and perceptual quality are improved significantly when the proposed JND adjustment process is applied.

• Fibers and Polymers
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• 제6권2호
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• pp.156-161
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• 2005

The gray line-profile method is introduced to find fabric density. Some patterned fabrics like stripe design as well as solid fabrics of basic weave structures are used to verify the efficiency and accuracy of the method. The approach is compared with Fourier transform method. Although the gray line-profile method is concise, it shows good results in both solid and patterned fabrics. In addition, it does not require a pre-processing or filtering technique in space or frequency domain to enhance the image suitable for the analysis. However, the approach is slightly influenced by the filter size for finding the local minimums of profile graph.

• 산업기술연구
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• 제18권
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• pp.295-302
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• 1998

Classification of fingerprints is one of the major subjects on which many researchers have been studying for efficient identification. But fingerprints should be preprocessed in various ways prior to being classified. Factors such as the accuracy and the processing time should be considered in classification of fingerprints. In this paper, we propose a method for classifying fingerprints into several frequent patterns. This method consists of two stages. A fingerprint image is first converted to a skeleton form to find out the center. Then it is identified as a member of one of preclassified pattern by the frequency domain feature. Experiments show that the proposed method is quite useful in classifying fingerprints into typical patterns.

• 한국측량학회지
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• 제33권6호
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• pp.517-526
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• 2015

Among the various image fusion or pan-sharpening methods, those wavelet-based methods provide superior radiometric quality. However, the fusion processing is not only simple but also flexible, since many low- and high-frequency sub-bands are often produced in the wavelet domain. To address this issue, a novel DT-CWT (Dual-Tree Complex Wavelet Transform) proportional to the fusion method by a WZP (Wavelet Zero-Padding) is proposed. The proposed method produces a single high-frequency image in the spatial domain that is injected into the LRM (Low-Resolution Multispectral) image. Thus, a wavelet domain fusion can be simplified to spatial domain fusion. In addition, in the proposed DT-CWTP (DT-CWT Proportional) fusion method, it is unnecessary to decompose the LRM image by adopting WZP. The comparison indicates that the proposed fusion method is nearly five times faster than the DT-CWT with SW (Substitute-Wavelet) fusion method, meanwhile simultaneously maintaining the radiometric quality. The conducted experiments with WorldView-2 satellite images demonstrated promising results with the computation efficiency and fused image quality.