• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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• pp.96-98
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• 2006

A new ex-situ model to diagnose a plasma processing equipment was presented. The model was constructed by combining wavelet, scanning electron microscope, ex-situ measurement of etching profile, and neural network. The diagnosis technique was applied to a tungsten etching process, conducted in a $SF_6$ helicon plasma. The wavelet was used to characterize detailed variations of plasma-etched surface. The diagnosis model was constructed with the vertical wavelet component. For comparison, a conventional model was built by using the estimated profile data. Compared to the conventional model, the wavelet-based model, demonstrated a much improved diagnosis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.173-174
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• 2008

Wavelet transform is a new method for power system analysis. On the basis of extensive investigation, optimal mother wavelets for the detection of leakage current are chosen. The recommended mother wavelet is 'Daubechies 4' wavelet. This paper proposes a technique for modeling toe finding point of leakage current in distribution system using wavelet transform and EMTP MODELS.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.246-249
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• 2009

Due to the additive white Gaussian noise (AWGN), images are often corrupted. In recent days, Bayesian estimation techniques to recover noisy images in the wavelet domain have been studied. The probability density function (PDF) of an image in wavelet domain can be described using highly-sharp head and long-tailed shapes. If a priori probability density function having the above properties would be applied well adaptively, better results could be obtained. There were some frequently proposed PDFs such as Gaussian, Laplace distributions, and so on. These functions model the wavelet coefficients satisfactorily and have its own of characteristics. In this paper, mixture distributions of Gaussian and Laplace distribution are proposed, which attempt to corporate these distributions' merits. Such mixture model will be used to remove the noise in images by adopting Maximum a Posteriori (MAP) estimation method. With respect to visual quality, numerical performance and computational complexity, the proposed technique gained better results.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 가을 학술발표회 논문집
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• pp.194-200
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• 1999

Localized damage to a structure affects its dynamic properties, and much work has been undertaken investigating the variation of natural frequencies, damping ratios and mode shapes. This paper presents a technique based on wavelet transform to detect the existences and locations of structural damages. The procedure operates solely on the mode shape from the damaged structure, and does not require a priori knowledge of the undamaged structure. The procedure is developed using a 32-story shear building model. Applying wavelet transform to the mode shape successfully identifies the location of damage. The procedure is best suited to the mode shape obtained from the fundamental natural frequency. The wavelet coefficients from the higher mode shapes can be used to verify the location of damage, but they are not as sensitive as the wavelet coefficients of the lower mode shapes.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.333-334
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• 2006

In this study, information compression based on the wavelet technique is described. The principle of signal or image compression is performed by optimization of quantization, that is the bit allocation taking advantage of their energy concentration in low frequency components. The wavelet transform is one of frequency decomposition, such as the discrete cosine transform or sub-band filtering, and it is also implemented as a filter bank. Wavelet transform with use of spatially localized basis function can reduce several drawbacks in conventional methods. The benifit of wavelet based compression method is described as comparing the transform method to another ones.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2003년도 하계학술대회 논문집
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• pp.284-287
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• 2003

A wavelet transform which is presented as a new technique of signal processing field decompose input signals into subsignals for expressing them in different resolutions and into detail signals for expressing the remaining signals. And the signals obtained from the progress include the information about input signals at the same time and scale. And when two wavelet bases are designed to form Hilbert transform pair, wavelet Pair show superior performance than the existing DWT in data detection of pulse type. Therefore in this paper, we detected position of impulse noise by using two dyadic wavelet bases which are designed by truncated coefficient vector.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2040-2042
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• 2003

In this paper, we propose a new method about wavelet-based fuzzy modeling using a DNA coding method. DNA coding techniques is known that expression of knowledge is various than Genetic Algorithm(GA) usually by made optimization technique because done base in structure of biologic DNA and optimization performance is superior. The reposed method make fuzzy system model in wavelet transform and equivalence relation after identification with coefficient of wavelet transform using a DNA coding techniques. Also, can get fuzzy model effectively of nonlinear system using advantage of strong wavelet transform about function that have sudden change. In this paper, in order to demonstrate the superiority of the proposed method compared with GA.

• 한국정보통신학회논문지
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• 제12권12호
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• pp.2365-2370
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• 2008

본 논문에서는 비선형 시스템의 위치 제어를 위하여 웨이블렛 신경회로망 제어기를 구성하였으며, 웨이블렛 신경회로망은 LQR 제어기의 성능을 향상 시킬 목적으로 사용한다. 불안전한 비선형 시스템을 선형화 시키고 안정화된 선형 시스템을 만들기 위하여 LQR를 사용하며, 외란에 효과적으로 적응하기 위하여 웨이블렛 신경회로망 제어기를 사용한다. 이 제어기를 비선형 시스템의 위치 제어에 적용하여 실험을 통해 그 유효성을 검정하였다.

• ETRI Journal
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• 제44권5호
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• pp.826-836
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• 2022

Signal decomposition is a computational technique that dissects a signal into its constituent components, providing supplementary information. In this study, the capability of two common signal decomposition techniques, including wavelet-based and empirical mode decomposition, on preterm birth classification was investigated. Ten time-domain features were extracted from the constituent components of electrohysterogram (EHG) signals, including EHG subbands and EHG intrinsic mode functions, and employed for preterm birth classification. Preterm birth classification and anticipation are crucial tasks that can help reduce preterm birth complications. The computational results show that the preterm birth classification obtained using wavelet-based decomposition is superior. This, therefore, implies that EHG subbands decomposed through wavelet-based decomposition provide more applicable information for preterm birth classification. Furthermore, an accuracy of 0.9776 and a specificity of 0.9978, the best performance on preterm birth classification among state-of-the-art signal processing techniques, were obtained using the time-domain features of EHG subbands.

• 한국멀티미디어학회논문지
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• 제6권5호
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• pp.861-869
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• 2003

멀티미디어 네트워크 시스템의 급속 성장으로 불법적인 복제가 되어진 디지털 콘텐츠가 많이 만들어지고 있다. 디지털 콘텐츠 중 영상정보에 대한 저작권 보호를 위해 워터마크 기법이 사용되어진다. 저작권보호는 영상의 불법복제의 인식이나 소유권 인증을 포함한다. 본 논문에서는 웨이블릿 영역에서 HVS(human visual system) 특성 및 적응 스케일 계수를 이 용한 이진영상을 워터마크신호로 사용하는 워터마킹 알고리듬을 제안하였다. 원 영상을 3-Level로 웨이블릿 변환을 하여, 기저대역 및 고주파 부대역에 워터마크 정보를 삽입하였다. 저주파에 해당하는 기저대역은 견고성을 고려한 것이고, 고주파 부대역은 인간 시각 시스템과 비가시성을 고려한 것이다. 워터마크 신호에 해당하는 이진 영상은 소유권 보호를 위하여 HVS 및 랜덤치환 기법을 사용하였다. 제안한 워터마킹 방법을 여러 가지 공격에 대한 실험을 한 결과로 비가시성 및 견고성에서 우수함을 확인 할 수 있었다.