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다중경로의 적응적 인식 및 복소 적응필터에 의한 칼라 TV의 고스트 제거
이경태,김종기,안상호,송규익,이건일,김덕규,김병해 경북대학교 전자기술연구소 1991 電子技術硏究誌 Vol.12 No.1
A ghost cancellation using an adaptive multi-path identification and a complex adaptive filter is proposed. The ghost reduction operation performs on the composite format signal in video baseband, and the delay time, the attenuation and the phase difference of multipath for minimizing color TV ghost are all cosidered. An adaptive algorithm uses complex LMS(least mean square) algorithm which is simple relatively. The influences of the luminance and the color signal by the phase difference are investigated and the performance of real processing and that of complex processing is compared. And the performance of the proposed method and that of the conventional RLMS filter is compared. In results, we show that the luminance and the color signal are considerably influenced by the phase difference and it& influences are greatly reduced by the complex adaptive filtering. And we verify that the computational efficiency and the D/U correspond to S/N of the proposed method are better than those of RLMS filter.
이건일,김덕규 경북대학교 전자기술연구소 1981 電子技術硏究誌 Vol.2 No.1
Microprocessor-controlled digital speed control system of chopper-fed do series motor has been designed. By keeping speed constant, the actual speed is measured and compared in the microprocessor with the desired speed setting which was given from external toggle switch or keyboard. Then produced error is used to adjust the 'ON' time of SCR chopper and the output voltage of the programmable power supply such that motor speed has fast response and is maintained at its desired value. The prototype's transient response is improved than the system without control and steady-state error is less than ±25%.
MPEG 의 화질 향상을 위한 새로운 적응 양자화 방법
이태호,황희철,김덕규,정태연 경북대학교 전자기술연구소 2001 電子技術硏究誌 Vol.22 No.1
In this paper, we proposed a new adaptive quantization algorithm to improve image quality. MPEG uses the effect that visibility of noise is less in high activity regions than in low activity regions. By using the effect, the part of image in high activity regions is coarsely quantized without seriously degrading the image quality. But, in this way, the reconstructed images have the degradations in the blocks having edges or fast and complex motion that is not well compensated normally. In this paper, we propose a new method adaptive quantization by using DCT coefficient and difference image for improving the image quality.
이태호,김광용,김상규,김덕균 경북대학교 전자기술연구소 2001 電子技術硏究誌 Vol.22 No.1
In this paper, We present a fast and efficient search algorithm for block motion estimation that produces better quality performance and less computational time compared with a three-step search (TSS) and Previously the proposed Two Step Search Algorithm (TWSS) by Fang-Hsuan Cheng and San-Nan sun. To improve quality performance and compurational time, the proposed algorithm in this paper considers spatial and temporal correlation using neighbor and previous blocks to improve quality performance.
EARLY SCIENCE WITH THE KOREAN VLBI NETWORK: EVALUATION OF SYSTEM PERFORMANCE
Lee, Sang-Sung,Petrov, Leonid,Byun, Do-Young,Kim, Jongsoo,Jung, Taehyun,Song, Min-Gyu,Oh, Chung Sik,Roh, Duk-Gyoo,Je, Do-Heung,Wi, Seog-Oh,Sohn, Bong Won,Oh, Se-Jin,Kim, Kee-Tae,Yeom, Jae-Hwan,Chung, American Institute of Physics 2014 The Astronomical journal Vol.147 No.4
<P>We report the very long baseline interferometry (VLBI) observing performance of the Korean VLBI Network (KVN). The KVN is the first millimeter-dedicated VLBI network in East Asia. The KVN consists of three 21 m radio telescopes with baseline lengths in a range of 305-476 km. The quasi-optical system equipped on the antennas allows simultaneous observations at 22, 43, 86, and 129 GHz. The first fringes of the KVN were obtained at 22 GHz on 2010 June 8. Test observations at 22 and 43 GHz on 2010 September 30 and 2011 April 4 confirmed that the full cycle of VLBI observations works according to specification: scheduling, antenna control system, data recording, correlation, post-correlation data processing, astrometry, geodesy, and imaging analysis. We found that decorrelation due to instability in the hardware at times up to 600 s is negligible. The atmosphere fluctuations at KVN baseline are partly coherent, which allows us to extend integration time under good winter weather conditions up to 600 s without significant loss of coherence. The post-fit residuals at KVN baselines do not exhibit systematic patterns, and the weighted rms of the residuals is 14.8 ps. The KVN is ready to image compact radio sources both in snapshot and full-track modes with residual noise in calibrated phases of less than 2 deg at 22 and 43 GHz and with dynamic ranges of ~300 for snapshot mode and ~1000 for full-track mode. With simultaneous multi-frequency observations, the KVN can be used to make parsec-scale spectral index maps of compact radio sources.</P>
불균형 이진 트리를 이용한 DCT 기반 벡터 양자화 코드북 설계
이경환,김덕규,이법기,최정현,정태연 경북대학교 전자기술연구소 1997 電子技術硏究誌 Vol.18 No.1
The performance of VQ mostly depends on codebook design method. LBG algorithm is a well known codebook design method. But it is dorminated by initial codebook and has a long computation time. The method of DCT-based design using binary tree was proposed for reducing computation time. However, degradations appear in the edge region of reconstructed image since the blocks of shade region are frequently selected for codevector. In this paper, we propose DCT-based vector quantization codebook design using unbalanced binary tree. As node prunings of shade region are constrained, the number of edge codevector is increased. From simulation results, this method sincerely reconstructs edge region with higher PSNR.