• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.4
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• pp.373-385
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• 1987

The scaled WDF should be optimized from the point of view of dynamic range. Transformer scaling method is attempted to maximize the dynamic range by equalizing the gains in the different nodes of the WDF. In this paper, the dual network and different frequencies are used to study the effects of different topology and of sampling frequency. Comparing with the unscaled WDF, the most significant observation is that the SNR is improved in the range of 7 to 35 dB in the WDF scaled by the trasnsformer scaling method. In addition, the SNR shows a continuous drop with the increase of sampling frequency, but scaling effects seem to decrease the rate at which the SNR drop.

• Broadcasting and Media Magazine
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• v.24 no.4
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• pp.87-101
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• 2019

JVET(Joint Video Experts Team)에서 새로운 비디오 압축 표준으로 진행 중인 VVC(Versatile Video Coding)에서는 HEVC(High Efficiency Video Coding)의 기술을 근간으로 부호화 효율을 높일 수 있는 다양한 새로운 기술들을 채택하고 있다. 인루프 필터(In-Loop Filter)는 복원영상의 화질을 향상시키기 위한 기술로 주관적 화질 개선뿐만 아니라 부호화 효율을 향상시키는 기술로 기존 HEVC의 확장 기술 및 새로운 인루프 필터 기술을 채택하고 있다. 본 고에서는 VVC의 CD에 채택되어 있는 인루프 필터 기술들을 소개한다. 인루프 필터 기술은 HEVC에 채택되어 있는 디블록킹 필터(Deblocking Filter: DF)와 SAO(Sample Adaptive Offset), 새로이 추가된 ALF(Adaptive Loop Filter)의 3가지의 필터와 LMCS(Luma Mapping with Chroma Scaling) 기술을 포함하고 있다. 이들 인루프 필터 기술은 주관적 화질 개선과 부호화 효율을 크게 개선하고 있으며, 2020년 7월 FDIS(Final Draft International Standard) 완료를 앞두고 인루프 필터링의 다양화로 인한 성능과 복잡도를 고려한 간소화 및 병렬처리 등의 고속화에 대한 표준화가 지속적으로 이루어질 전망이다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.4
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• pp.233-242
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• 2023

The unscented Kalman filter (UKF), which is widely used to estimate the states of nonlinear dynamic systems, can be improved to realize robust system identification by using multiple sigma-point sets. When using Kalman filter methods for system identification, artificial noises must be appropriately selected to achieve optimal estimation performance. Additionally, an appropriate scaling factor for the sigma-points must be selected to capture the nonlinearity of the state-space model. This study entailed the use of Bouc-Wen hysteresis model to examine the nonlinear behavior of a single-degree-of-freedom oscillator. On the basis of the effects of the selected artificial noises and scaling factor, a new UKF method using multiple sigma-point sets was devised for improved robustness of the estimation over various signal-to-noise-ratio values. The results demonstrate that the proposed method can accurately track nonlinear system states even when the measurement noise levels are high, while being robust to the selection of artificial noise levels.

• ETRI Journal
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• v.32 no.6
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• pp.921-931
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• 2010

It has been shown that the principal subspace-based multichannel Wiener filter (MWF) provides better performance than the conventional MWF for suppressing interference in the case of a single target source. It can efficiently estimate the target speech component in the principal subspace which estimates the acoustic transfer function up to a scaling factor. However, as the input signal-to-interference ratio (SIR) becomes lower, larger errors are incurred in the estimation of the acoustic transfer function by the principal subspace method, degrading the performance in interference suppression. In order to alleviate this problem, a principal subspace modification method was proposed in previous work. The principal subspace modification reduces the estimation error of the acoustic transfer function vector at low SIRs. In this work, a frequency-band dependent interpolation technique is further employed for the principal subspace modification. The speech recognition test is also conducted using the Sphinx-4 system and demonstrates the practical usefulness of the proposed method as a front processing for the speech recognizer in a distant-talking and interferer-present environment.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1495-1498
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• 1987

This paper described the design of register part, ROM and entire digital filter implementation by merging with ALU, control part last year. The register part consists of shift register, parallel load serial output register, multiplexer and selector, and we designed specially the 1024 memory cells ROM and decoder to decode the register data. Also, presented scaling algorithm to prevent the overflow.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2001.11a
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• pp.464-468
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• 2001

In this paper, we propose a robust watermarking technique that accepts time scaling, pitch shift, add noise and a lot of lossy compression such as MP3, AAC, WMA. The technique is developed based on digital filtering. Being designed according to critical band of HAS (human auditory system), the digital filters nearly affect audio quality. Furthermore, before implementing digital filtering, wavelet transform decomposes the audio signal into several signals that is composed of specific frequencies. Designed digital filters scan the decomposed signal. The designed digital filter, band-stop filter, distorts and eliminates specific frequencies of audio signals. Watermarking detection can be accomplished by FFT (Fast Fourier Transform). Firstly, segments of audio signal are transformed by FFT. Then, the obtained amplitude spectrum by FFT is summed repeatedly. Finally the watermark detector can find filters used to watermark encoding based on eliminating frequencies. The suggested technique can embed 4bits/s in a robust manner.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04b
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• pp.529-531
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• 2000

웨이블릿 디노이징 기법은 웨이블릿 계수들의 thresholding 에 의해 부가적인 가우시안 노이즈들을 제가하는데 사용된다. 필터에 기반한 다른 많은 변환들처럼, 웨이블릿 scaling 방법들은 이미지의 경계선들의 근처에 블러링 현상이나 인공적인 잡음들이 나타나게 된다. 본 논문에서 구현하고자 하는 웨이블릿 변환 필터의 구현 배경은 경계선 부분의 손실없이 이미지의 노이즈 제거를 위한 것이다. 많은 이미지 향상과 회복기법들은 이러한 붕괴처리의 효과들을 위한 보상으로 개발되었다. 또한 뉴럴 필터, 퍼지 필터, LMS L-filter, quadratic filter, sigma filter 등은 이러한 이미지의 질을 개선하기 위한 수학적인 도구들이라고 할 수 있다. [1]

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.3
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• pp.16-22
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• 1985

In this paper a new algorithm named modified delta modulation (MDM) for encoding filter coefficients is proposed. And this paper presents the designing method of multiplier less FIR filters rosin영 Proposed MDM a19orithm. In the delta modulation (DM) system the quantiaation levels consist of two levels $\pm$1, but in newly proposed MDM algorithm quantization levels are extended to many levels 0, $\pm$2$^n$, n=0, 1, 2... It is recognized by the result of computer simulations that frequency response of multi-plierless FIR filters designed by MDM algorithm is relatively good. And comparing with con-ventional FIR filters on the number of hardware devices, this filter needs a little increased memory, but regardless of filter order it needs only one multiplier which is used for signal scaling.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.1
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• pp.171-182
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• 2015

The general wavelet transform has profitable property in non-stationary signal analysis specially. The tunable Q-factor wavelet transform is a fully-discrete wavelet transform for which the Q-factor Q and the asymptotic redundancy r, of the transform are easily and independently specified. In particular, the specified parameters Q and r can be real-valued. Therefore, by tuning Q, the oscillatory behavior of the wavelet can be chosen to match the oscillatory behavior of the signal of interest, so as to enhance the sparsity of a sparse signal representation. The TQWT is well suited to fast algorithms for sparsity-based inverse problems because it is a Parseval frame, easily invertible, and can be efficiently implemented. The transform is based on a real valued scaling factor and is implemented using a perfect reconstruction over-sampled filter bank with real-valued sampling factors. The transform is parameterized by its Q-factor and its over-sampling rate, with modest over-sampling rates being sufficient for the analysis/synthesis functions to be well localized. This paper describes filter design of 2D discrete-time wavelet transform for which the Q-factor is easily specified. With the advantage of this transform, perfect reconstruction filter design and implementation for performance improvement are focused in this paper. Hence, the 2D transform can be tuned according to the oscillatory behavior of the image signal to which it is applied. Therefore, application for performance improvement in multimedia communication field was evaluated.

• The Journal of the Korea Contents Association
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• v.4 no.4
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• pp.179-187
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• 2004

In this paper, we have designed an LCD controller based on AMBA. Normally display systems using the LCD are adopted independent bus architecture for high speed data access. Proposed LCD controller complies with AMBA data format and has an image scaler that executes interpolation for full screen display. This image scaler employs FOI for horizontal scaling and H-Shape pseudomedian filter for vertical scaling. It has been designed with VHDL and verified on prototype board using Xilinx FPGA and LCD panel.