• 대한수학회지
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• 제59권3호
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• pp.495-517
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• 2022

Let M_α be a bilinear fractional maximal operator and BM_α be a fractional maximal operator associated with the bilinear Hilbert transform. In this paper, the compactness on weighted Lebesgue spaces are considered for commutators of bilinear fractional maximal operators; these commutators include the fractional maximal linear commutators M^j_α,β and BM^j_α,β (j = 1, 2), the fractional maximal iterated commutator ${\mathcal{M}}_{{\alpha},{\vec{b}}}$, and $BM_{{\alpha},{\vec{b}}}$, where b ∈ BMO(ℝ^d) and ${\vec{b}}\;=\;(b_1,b_2)\;{\in}\;BMO({\mathbb{R}}^d)\;{\times}\;BMO({\mathbb{R}}^d)$. In particular, we improve the well-known results to a larger scale for 1/2 < q < ∞ and give positive answers to the questions in [2].

• 대한수학회보
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• 제33권4호
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• pp.545-551
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• 1996

It is well known in the theory of distributions and proved in [GS, S] that $$ (i) (Bochner-Schwartz) Every positive definite (tempered) distribution is the Fourier transform of a positive tempered measure \mu. $$ $$ (ii) (Schwartz kernel theorem) Let B(\varphi, \psi) be a bilinear distribution. Then for some u \in D'(R^n \times R^n) B(\varphi, \psi) = u(\varphi(x)\bar{\psi}(y)) for every \varphi, \psi \in C_c^\infty. $$ $$ (iii) A translation invariant positive definite bilinear distribution B(\varphi, \psi) is of the form B(\varphi, \psi) = \smallint \varphi(x)\psi(x) d\mu(x) for every \varphi, \psi \in C_c^\infty (R^n), where \mu is a positive tempered measure.

• International Journal of Contents
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• 제6권4호
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• pp.1-7
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• 2010

Natural images often contain useful information about the scene such as text or company logos placed on a rectangular shaped plane. The 2D images captured from such objects by a camera are often distorted, because of the effects of the perspective projection camera model. This distortion makes the acquisition of the text information difficult. In this study, we detect the rectangular object on which the text is written, then the image is restored by removing the perspective distortion. The Hough transform is used to detect the boundary lines of the rectangular object and a bilinear transformation is applied to restore the original image.

• 대한전자공학회논문지
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• 제27권5호
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• pp.808-815
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• 1990

This paper treats with the design method for the single loop oversampled Sigma-Delta A/D converter with one delay and the digital integrator. Such an integrator was kgenerated by means of the bilinear transform of the analog integrator. The frequency spectrums of the quantizer and the decimator output signal are evaluated by FFT respectively. With the performance evaluation system, the values of SNR are obtained versus the input sinusoidal signal amplitude, frequency, the oversampling ratio, the DC-input level, the loop gain and the limitting value of the integrator. As compared with existing results, values of SNR versus the input signal amplitude and the oversampling ratio for the suggested system are about 6dB higher then previously reported results respectively. Furthermore, this approach achieves an about 60dB input dynamic range.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1995년도 추계학술대회논문집; 한국종합전시장, 24 Nov. 1995
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• pp.227-232
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• 1995

This paper presents a digital modeling technique for the distributed parameter system. The basic idea of the proposed technique is to discretize a continuous system with respect to the spatial coordinate using the approximate methods such as bilinear method and backward difference method. The response of the discretized system is analyzed by Laplace transform and Z transform. The computational result of the proposed technique in a torsional shaft is compared with the exact solution and the result of the finite element method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 G
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• pp.2411-2413
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• 1998

In this paper, using tile concept of block digital filtering, and the design procedure of time-interleaved oversampling converter are presented. it is shown that arbitrary sigma-delta A/D converter can be converted into corresponding time-interleaved structure. The TIM structure of this paper is designed by the bilinear transform. To verify the simulation results, a second-order TIM structure A/D converter has been implemented and the design process as well as experimented results are presented.

• 한국의학물리학회지:의학물리
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• 제11권1호
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• pp.39-47
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• 2000

신경 외과적 수술의 한분야인 정위적 방사선 수술은 두 개강 내의 병변의 위치 계산 후, 고선량의 방사선을 조사하여 병변을 치료하는 방법이기 때문에, 효과적인 수술을 위해서는 병변의 정확한 위치 정보가 무엇보다도 중요하다. 본 연구에서는 DSA(Digital Subtraction Angiography) 영상이 내재적으로 이미지 왜곡이라는 문제점을 가지고 있기 때문에, 이것의 보정을 통하여 더욱 정확한 target 위치를 계산하였다 이미지 왜곡을 보정하기 위하여 grid 팬텀을 제작하였고, localization 알고리즘의 정확도를 평가하기 위하여, target 팬텀을 제작하였다. Image Intensifier의 앞쪽에 grid 팬텀을 부착하고, target 팬텀을 Leksell Frame에 고정시킨 후, DSA 영상을 얻었다. 본 실험을 위하여 개발된 프로그램을 이용하여, Anterior and Posterior, Left and Right 영상에서 bilinear transform을 적용하여 왜곡을 보정한 후, target 위치를 계산하였다. 그리고, 이와 같은 방법을 통하여 계산된 target 위치 좌표와 target 팬텀의 절대 좌표의 비교를 통하여 localization 오차가 계산되었다. 이번 실험의 결과는 왜곡을 보정하지 않은 경우, localization 오차는 $\pm$0.41mm, 왜곡 보정을 한 경우는 $\pm$0.34mm이었다. 따라서 본 연구에서 개발된 알고리즘 정밀도가 인정되며, 환자의 치료에 적합한 것으로 사료된다.

• 한국소음진동공학회논문집
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• 제22권3호
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• pp.291-297
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• 2012

Conventional Fourier analysis can give only limited information about the dynamic characteristics of nonstationary signals. Instead, time-frequency analysis is widely used to investigate the nonstationary signal in detail. Several time-frequency analysis methods are compared for a typical acoustic emission burst generated during the impact between a ferrite ceramic and aluminum plate. This AE burst is inherently nonstationary and random containing many frequency contents, which leads to severe interference between cross terms in bilinear convolution type distributions. The smoothing and reassignment processes can improve the readability and resolution of the results. Spectrogram and scalogram of the AE burst are obtained and compared to get the characteristics information. Renyi entropies are computed for various bilinear time-frequency transforms to evaluate the randomness. These bilinear transforms are reassigned by using the improved algorithm in discrete computation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.157-160
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• 1996

Physical systems axe generally continuous-time in nature. However as the data measured from these systems is generally in the form of discrete samples, and most modern signal processing is performed in the discrete-time domain, discrete-time models are employed. This paper describes methods for estimating the coefficients of continuous-time system within a closed loop control system. The method employs a recursive estimation algorithm to identify the coefficients of a discrete-time bilinear-operator model. The coefficients of the discrete-time bilinear-operator model closely approximate those of the corresponding continuous-time Laplace transform transfer function.

• 한국통신학회논문지
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• 제4권1호
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• pp.25-31
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• 1979

All the resitors in the active RC filter networks can be relplaced by the switched capacitors. Therefore, An SC filter circuit can be fully integrated using MOS technology. A switched capacitor is much better than a resistor in temperature and linearity characteristics, and the former can be fabricated on the much smaller area then the latter. In this paper, It is given the generalized disign method of the active SC filter from the active RC filter using Bilinear Z-transformation. By SC filtering Techniques using Bilinear Z-transform, It enalbes us to realize the FDNR and Gyrator filters, which could not be realized in the exsisting designs, and it permits the processing of signals at much higher frequenies that many previous designs do. Experiments show that the response of the SC active filter is similiar to that of its prototype active RC filter.