• 전기학회논문지
• /
• 제61권1호
• /
• pp.117-124
• /
• 2012

In this paper, we present some remarks on the correlations between s and w domains when a discrete-time transfer function is converted from z-plane by using the w-transform. With time response specifications, when a digital filter or controller is designed in z-plane, the w-transform is useful for the purpose if only the w-transformed system closely approximates to the continuous-time system. It will be shown that the approximation is accomplished only in the specific region depending on sampling time. Also, it is noted that such an approximation should be carefully dealt with for the case where a discrete-time reference transfer function is synthesized for the use of direct digital design.

• 한국소음진동공학회논문집
• /
• 제16권6호
• /
• pp.627-633
• /
• 2006

The tire is considered as one of the important noise sources having an influence on vehicle's performance. The Pattern noise of a tire is the transmission sound of airborne noise. On smooth asphalt road, Pattern noise is amplified with the velocity. In recent, the study on the reduction of Pattern noise is energetically processed. Pattern noise is strongly related with pitch sequence. To reduce the pattern noise, tire's designer has to randomize the sequence of pitch. The FFT is a traditional method to evaluate the level of the randomization of the pitch sequence, but gives no information on time-varying, instantaneous frequency. In the study, we found that Time-Frequency transform is a useful method to non-stationary signal such as tire noise.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제7권4호
• /
• pp.247-253
• /
• 2007

In this paper, a high throughput multiple transform architecture for H.264 Fidelity Range Extensions (FRExt) is proposed. New techniques are adopted which (1) regularize the $8{\times}8$ integer forward and inverse DCT transform matrices, (2) divide them into four $4{\times}4$ sub-matrices so that simple fast butterfly algorithm can be used, (3) because of the similarity of the sub-matrices, mixed butterflies are proposed that all the sub-matrices of $8{\times}8$ and matrices of $4{\times}4$ forward DCT (FDCT), inverse DCT (IDCT) and Hadamard transform can be merged together. Based on these techniques, a hardware architecture is realized which can achieve throughput of 1.488Gpixel/s when processing either $4{\times}4\;or\;8{\times}8$ transform. With such high throughput, the design can satisfy the critical requirement of the real-time multi-transform processing of High Definition (HD) applications such as High Definition DVD (HD-DVD) ($1920{\times}1080@60Hz$) in H.264/AVC FRExt. This work has been synthesized using Rohm 0.18um library. The design can work on a frequency of 93MHz and throughput of 1.488Gpixel/s with a cost of 56440 gates.

• 호남수학학술지
• /
• 제26권4호
• /
• pp.401-409
• /
• 2004

In this paper, we show that C-resolvent of generator can be represented by Laplace transform and establish an exponential formula for C regularized semigroups whose antiderivatives are exponentially bounded.

• 한국음향학회지
• /
• 제19권8호
• /
• pp.54-62
• /
• 2000

적응 필터링 기법은 시간에 따라 신호의 통계적 특성이 변화한때 많이 응용되는 신호처리의 분야이다. 적응필터의 성능 평가는 보통 구조의 복잡도 (complexity), 수렴 속도 (convergence speed) 및 오조정 (misadjustment)을 가지고 평가한다. 적응 필터의 실시간 구현을 위해서는 구조가 간단해야 피고 수렴속도는 빨라야 한다. 본 연구에서는 수렴속도 향상을 위해 변환 평면에서의 적응 필터링 기법에 대해 제안하였다. 먼저 CZT (Chirp Z-Transform)의 주파수 확대해석하는 특성과 DCT (Discrete Cosine Transform)의 실수연산 특성을 모두 가지는 CDCT (Chirp Discrete Cosine Transform)을 제안하였고, 이를 이용한 CDCTLMS (Chirp Discrete Cosine Transform LMS)을 제안하였다. 제안된 방법은 기존의 NLMS (normalized least mean square)알고리즘과 대표적인 변환평면 적응 필터링 방법인 DCTLMS (discrete cosine transform LMS) 알고리즘과의 학습곡선 (loaming curve)의 비교를 통하여 우수함을 입증하였으며 실제 초음파 신호처리에의 응용을 보였다.

• Journal of applied mathematics & informatics
• /
• 제31권1_2호
• /
• pp.165-177
• /
• 2013

In this paper, we apply Homotopy perturbation transform method (HPTM) for solving singular fourth order parabolic partial differential equations with variable coefficients. This method is the combination of the Laplace transform method and Homotopy perturbation method. The nonlinear terms can be easily handled by the use of He's polynomials. The aim of using the Laplace transform is to overcome the deficiency that is mainly caused by unsatisfied conditions in other semi-analytical methods such as Homotopy perturbation method (HPM), Variational iteration method (VIM) and Adomain Decomposition method (ADM). The proposed scheme finds the solutions without any discretization or restrictive assumptions and avoids the round-off errors. The comparison shows a precise agreement between the results and introduces this method as an applicable one which it needs fewer computations and is much easier and more convenient than others, so it can be widely used in engineering too.

• 한국기계가공학회지
• /
• 제1권1호
• /
• pp.29-37
• /
• 2002

The wavelet transform is a popular tool for studying intermittent and localized phenomena in signals. In this study the wavelet transform of cutting force signals was conducted for the diagnosis of grinding conditions in grinding process. We used the Daubechies wavelet analyzing function to detect a sudden change in cutting signal level. STD11 workpiece was 85 times of machined pieces cut by the WA wheel and a tool dynamometer obtained cutting force signals. From the results of the wavelet transform, the obtained signals were divided into approximation terms and detailed terms. At dressing time, the approximation signals were slowly increased and 45 machined times noticed dressing time.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 춘계학술대회 논문집
• /
• pp.1063-1066
• /
• 2002

The wavelet transform is a popular tool for studying intermittent and localized phenomena in signals. In this study the wavelet transform of cutting force signals was conducted for the detection of a tool failure in turning process. We used the Daubechies wavelet analyzing function to detect a sudden change in cutting signal level. A preliminary stepped workpiece which had intentionally a hard condition was cut by the inserted cermet tool and a tool dynamometer obtained cutting force signals. From the results of the wavelet transform, the obtained signals were divided into approximation terms and detailed terms. At tool failure, the approximation signals were suddenly increased and the detailed signals were extremely oscillated just before tool failure.

• 충청수학회지
• /
• 제22권3호
• /
• pp.481-495
• /
• 2009

Huffman, Park and Skoug introduced various results for the $L_{p}$ analytic Fourier-Feynman transform and the convolution for functionals on classical Wiener space which belong to some Banach algebra $\mathcal{S}$ introduced by Cameron and Storvick. Also Chang, Kim and Yoo extended the above results to an abstract Wiener space for functionals in the Fresnel class $\mathcal{F}(B)$ which corresponds to $\mathcal{S}$. Moreover they introduced the $L_{p}$ analytic Fourier-Feynman transform for functionals on a product abstract Wiener space and then established the above results for functionals in the generalized Fresnel class $\mathcal{F}_{A1,A2}$ containing $\mathcal{F}(B)$. In this paper, we investigate more generalized relationships, between the Fourier-Feynman transform and the convolution product for functionals in $\mathcal{F}_{A1,A2}$, than the above results.

• 대한전자공학회논문지
• /
• 제26권10호
• /
• pp.1617-1623
• /
• 1989

The introduction of the fast Fourier transform(FFT),an efficient computational algorithm for the discrete Fourier transform(DFT) by Cooley and Tukey(1965), has brought to the limelight various other discrete transforms. Some of the analog functions from which these transforms have been derived date back to the early 1920's, for example, Walsh functions (Walsh, 1923) and Hadamard Transform(Enomoto et al, 1965). Fast algorithms developed for the forward transform are equally applicable, exept for minor changes, to the inverse transform. In this paper, we present a simple pipelined Hadamard matrix(HM) which is used to develop a fast algorithm for the Hadamard Processor (HP). The Fast Hadamard Transform(FHT) can be derived using matrix partitioning techniques. The HP system is incorporated through a modular design which permits tailoring to meet a wide range of video data link applications. Emphasis has been placed on a low cost, a low power design suitable for airbone system and video codec.