Design of LMS based adaptive equalizer using Discrete Multi-Wavelet Transform

최윤석,박형근,Choi, Yun-Seok,Park, Hyung-Kun The Korea Institute of Information and Commucation 2007 한국정보통신학회논문지 Vol.11 No.3

차세대 이동 멀티미디어 통신에서는 전송지연을 줄이고 버스트 시변채널의 시간변화를 제한하기 위해 버스트 전송이 많이 사용된다. 그러나 채널적응을 위한 훈련 심볼은 짧은 길이의 버스트 데이터에 대해 심각한 문제를 야기할 수 있다. 따라서 심볼에 대한 적응 등화기의 설계에 있어서 짧은 길이의 훈련 심볼과 빠른 수렴을 갖는 적응 알고리즘이 필요로 된다. 본 논문에서는 DMWT (discrete multi-wavelet transform)과 LMS(least mean square) adaptation 을 갖는 적응 등화기를 제안한다. 제안된 등화기는 복잡성의 증가를 최소화하면서도 현재의 transform-domain equalizer보다 빠른 수렴을 갖는다. In the next generation mobile multimedia communications, the broad band shot-burst transmissions are used to reduce end-to-end transmission delay, and to limit the time variation of wireless channels over a burst. However, training overhead is very significant for such short burst formats. So, the availability of the short training sequence and the fast converging adaptive algorithm is essential in the system adopting the symbol-by-symbol adaptive equalizer. In this paper, we propose an adaptive equalizer using the DWMT (discrete multi-wavelet transform) and LMS (least mean square) adaptation. The proposed equalizer has a faster convergence rate than that of the existing transform-domain equalizers, while the increase of computational complexity is very small.

비선형 HPA를 가진 M-QAM 시스템에서 비선형 Volterra 등화기의 수렴 속도 향상을 위한 병렬 M-band DWT-LMS 알고리즘

최윤석,박형근,Choi, Yun-Seok,Park, Hyung-Kun 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.7c

고효율 변조기법 (16 QAM or 64QAM)이 비선형 고전력 증폭기 (High-Power Amplifier; HPA)를 사용하는 통신시스템에 적용되었을 때 비선형 왜곡에 의해 성능저하가 발생할 수 있다. 이런 비선형 왜곡은 수신부에서 복잡도가 낮은 LMS 알고리즘을 적용한 적응적 비선형 Volterra 등화기를 사용하여 보상할 수 있지만, 매우 느린 수렴 속도를 가지는 단점이 있다. 본 논문에서는 수렴 속도를 향상시키기 위한 병렬 M대역 이산 웨이블릿 변환영역 LMS (Parallel M-band Discrete Wavelet Transform Least Mean Square) 알고리즘을 제안한다. 모의실험을 통하여 제안된 기법이 기존의 시간 영역 LMS 알고리즘과 변환 영역 LMS 알고리즘들에 비해 수렴 속도가 우수함을 보여준다. When a higher-order modulation scheme (16QAM or 64QAM) is applied to the communications system using the nonlinear high power amplifier (HPA), the performance can be degraded by the nonlinear distortion of the HPA. The nonlinear distortion can be compensated by the adaptive nonlinear Volterra equalizer using the low-complexity LMS algorithm at the receiver. However, the LMS algorithm shows very slow convergence performance. So, in this paper, the parallel M-band discrete wavelet transformed LMS algorithm is proposed in order to improve the convergence speed. Throughout the computer simulations, it is shown that the convergence performance of the proposed method is superior to that of the conventional time-domain and transform-domain LMS algorithms.

조망의 변화에 따른 교량경관조명의 휘도특성분석

최윤석,정인영,안현태,김정태,Choi, Yoon-Seok,Jeong, In-Young,Ahn, Hyun-Tae,Kim, Jeong-Tai 한국조명전기설비학회 2006 조명·전기설비학회논문지 Vol.20 No.6

본 연구는 휘도측정장비인 CS-100과 ProMetric 1400을 활용하여 조망점의 변화에 따른 교량 경관조명의 휘도를 분석한 것이다. 이를 위하여 경관조명이 적용된 한강의 교량4개를 교량형태별로 선정하고 조망유형에 따라 한강둔치에서 바라본 조망(투시뷰), 교량주변 건물에서 바라본 조망(건물뷰), 그리고 교량 위 주행자가 바라본 조망(주행뷰) 등 3가지로 분류하였다. 연구대상의 주변하늘, 강물표면, 상부구조물, 상판측면 그리고 교각에 대한 휘도분포를 측정하였다. 분석결과, 광진교와 동호대교는 투시뷰의 휘도가 높게 나타났으며, 올림픽대교와 동작대교는 건물뷰의 휘도가 높게 나타났다. 따라서 거더교와 같이 상부구조물이 없는 교량에서는 투시뷰가, 사장교 및 아치교와 같이 상부 구조물이 있는 교량에서는 건물뷰가 경관조명의 특성을 크게 반영하는 휘도분포가 강하게 나타났다. The study is to analyze the surface luminance of the illuminated bridges according to the change of view point using luminance measurements with instrument CS-100 and ProMetric 1400. For the purpose the illuminated bridges of the structure type were sleceted. Also, the view points were classified the three types which are a perspective view, a building view, a driver view. The luminance of the surrounding sky, surface of river, upper structure or bridge, girder side, and pier or the objects was measured. As a result of this study, The Kwangjin and Dongho Bridge showed the luminance distribution of a perspective view was high. And the Olympic and Dongjac bridge the luminance distribution of building view was high. The luminance effect of the girder bridge that has no upper structure was distinguished for the perspective view, and the cable-stayed girder bridge and the arch bridge were characterized as the building view.

경관조명의 시점거리별 표면휘도 특성분식

최윤석,정인영,안현태,김정태,Choi, Yoon-Seok,Jeong, In-Young,Ahn, Hyun-Tae,Kim, Jeong-Tai 한국조명전기설비학회 2006 조명·전기설비학회논문지 Vol.20 No.6

야간도시경관의 미적향상, 시각적 안전의 확보 및 빛 공해 방지 등을 고려한 기존의 경관조명 평가방법은 대부분 측정점을 한 지점으로 한정하여 조명물리량을 분석함으로써 거리에 따른 평가결과의 다양성이 소홀히 취급되었다. 본 연구는 측정거리의 변화에 따른 평가대상 구조물의 표면휘도를 고려한 경관조명 평가방법을 제시하는데 연구의 목적이 있다. 이를 위하여 경관조명이 설치된 한강의 교량을 대상으로 CS-100과 ProMetric 1400 등 디지털 측광기기와 경관조명 소프트웨어 Lightscape v3.2를 활용하였다. 즉 측정거리 100[m], 300[m], 500[m]로 구분하여 현장측정 및 컴퓨터 시뮬레이션을 실시한 결과 거리변화에 따른 휘도의 평가방법은 대상 구조물로부터 약 100[m] 이내에서 실시하는 것이 휘도측면에서 유리한 것으로 나타났다. Existing outdoor lighting evaluation methods for the city beautification at night, the measurements are limited by one point to analyze the photometric data. However, this methods could not represent the diversity of photometric result from the distance. This study aims to propose the new outdoor lighting evaluation method of structure surface luminance in accordance with the measuring distance. For the purpose, the field measurement and simulation of an illuminated structure were conducted by CS-100, Digital Photometry Instrument ProMetric 1400, and the Lightscape v 3.2 from the distance of 100[m], 300[m], 500[m]. The result shows that evaluation of the surface luminance by the distance should be measured from about 100[m] of an illuminated object for getting the familiar result from computer simulation.

휴대전화 단말기용 전파 흡수체의 개발에 관한 연구

최윤석,정재현,김동일,Choi Yun-Seok,Jung Jae-Hyun,Kim Dong-Il 한국전자파학회 2006 한국전자파학회논문지 Vol.17 No.5

본 논문은 실용적인 면을 고려한 휴대전화 단말기용 전파 흡수체 개발을 위해 연구하였다. 이에 Sendust 배합율, $Al(OH)_3$ 코팅 함유량, 시편의 두께, 지지재의 변화가 전파 흡수체의 전파 흡수능에 치는 영향을 연구하였다. 중심 주파수는 전파 흡수체의 두께가 1 mm, 2 mm, 3 mm로 증가할수록 2.2 GHz, 1.29 GHz, 842 MHz의 저주파대로 이동하였고, Sendust의 배합율이 80 wt%에서 85 wt%로 증가되면서 2.2 GHz에서 1.91 GHz로, 1.29 GHz에서 801 MHz로, 842 MHz에서 801 MHz로 각각 저주파대로 조절할 수 있었다. 전파 흡수 대역은 Sendust에 $Al(OH)_3$를 코팅했을 때가 코팅하지 않았을 때보다 흡수 대역이 넓어졌다. 이때 전파 흡수체는 지지재는 CPE로 하였으며, 제작 온도는 $70^{\circ}C$로 일정하게 하였다. 제작된 전파 흡수체는 두께가 0.85 mm일 때 1.8 GHz에서 5.76 dB의 우수한 전파 흡수능을 보였다. This paper deals with research for development of electromagnetic wave absorbers in sheet type for mobile phones. By controlling the sendust ratio, the $Al(OH)_3$ coating, the thickness, the kind of binders, and the milling time, electromagnetic wave absorbers were prepared and examined. Central frequency shills toward lower 2.2 GHz, 1.29 GHz, 842 MHz with increasing thickness 1 mm, 2 mm, 3 mm of the absorber, and absorption ability controlled each 2.2 GHz to 1.91 GHz, 1.29 GHz to 801 MHz, 842 MH2 to 801 MHz adjust sendust amount from 80 wt% to 85 wt%. The absorption band of the electromagnetic wave absorber coated with $Al(OH)_3$ becomes larger than that of non-coated one. Sendust composite microwave absorbers mixed with CPE were prepared at $70^{\circ}C$ in temperature. The fabricated electromagnetic wave absorbers show a reflection coefficient 5.76 dB at 1.8 GHz in thickness of 0.85 mm.

Synthesis, Spectral Property and Dyeing Assessment of Azo Disperse Dyes Containing Carbonyl and Dicyanovinyl Groups

최윤석,Kun Su Lee,Hye Jin Kim,Jong Yun Choi,Soon Bang Kang,Eui Jae Lee,금교창 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.3

A series of azo disperse dyes having dicyanovinyl groups was synthesized by the Knoevenagel condensation with malononitrile from carbonyl substituted phenylazo disperse dyes which were prepared by conventional diazo coupling reaction of aniline derivatives as diazo components. A variety of coupling components such as anilines, an indole and a pyridone were used. The azo disperse dyes were evaluated for their spectral properties and dyeing assessment on the polyester fabrics. The azo disperse dyes containing dicyanovinyl groups showed bathochromic shifts and darker colors due to increased electron withdrawing strength in their azo components and extended conjugation by dicyanovinyl groups than their parent carbonyl substituted azo dyes. The dyes containing 2-acetylamino-5-methoxy substituent in the coupling component exhibited higher wavelength of maximum absorbance (λmax) and significant negative solvatochromism than those of other dyes due to intramolecular hydrogen bonding.

HWSD와 정밀토양도를 이용한 유출해석시 토양 매개변수 특성 비교 평가

최윤석,정영훈,김주훈,김경탁,Choi, Yun Seok,Jung, Young Hun,Kim, Joo Hun,Kim, Kyung-Tak 한국농공학회 2016 한국농공학회논문집 Vol.58 No.4

Harmonized World Soil Database (HWSD) including the global soil information has been implemented to the runoff analysis in many watersheds of the world. However, its accuracy can be a critical issue in the modeling because of the limitation the low resolution reflecting the physical properties of soil in a watershed. Accordingly, this study attempted to assess the effect of HWSD in modeling by comparing parameters of the rainfall-runoff model using HWSD with the detailed soil map. For this, Grid based Rainfall-runoff Model (GRM) was employed in the Hyangseok watershed. The results showed that both of two soil maps in the rainfall-runoff model are able to well capture the observed runoff. However, compared with the detailed soil map, HWSD produced more uncertainty in the GRM parameters related to soil depth and hydraulic conductivity during the calibrations than the detailed soil map. Therefore, the uncertainty from the limited information on soil texture in HWSD should be considered for better calibration of a rainfall-runoff model.

레이들 내 와류 형성에 미치는 노즐 편심도의 영향에 관한 수치해석

최윤석,서준원,이진형 ( Yun Suk Choi,Jun Won Suh,Zin Hyoung Lee ) 한국주조공학회 1998 한국주조공학회지 Vol.18 No.1

N/A In steel making process, vortices may develope during the tapping of steel from ladle to tundish which take down undesired slag in their core. If the slag is dispersed finely in the melt, it can flow down further into the mold and finally becomes inclusion in the steel. Therefore, the suppression of the vortex formation is very important in steel making process. One of the methods used to suppress the vortex formation is using nozzle eccentricity. In this study the flow field and the free surface change during the drainage of melt from ladle were analyzed numerically with a commercial FDM package, CFX-F3D, to find out the effect of nozzle eccentricity. This calculation results showed the suppression effect of vortex formation by nozzle eccentricity in agreement with experiment. (Received November 14, 1997)

폐 브라운관(CRT) 유리를 잔골재로 대체한 방사선 차폐 채움재의 성능평가

최윤석,장필성,박옥윤,장현오,Choi, Yoon-Suk,Jang, Pil-Sung,Park, Ok-Yun,Jang, Hyun-O 한국건설순환자원학회 2019 한국건설순환자원학회지 Vol.14 No.1

Glucose Transporter-1 Expression in Squamous Cell Carcinoma of the Tongue

최윤석,Seok Jin Kim,Dae Sik Kim,Seh Jong Park,Yong Park,Hye Jin Shin,Kwang-Yoon Jung,Seung-Kuk Baek,Bong Kyung Shin,Jung Woo Choi,Byung Soo Kim,Sang Won Shin,Yeul Hong Kim,Jun Suk Kim 대한암학회 2007 Cancer Research and Treatment Vol.39 No.3

Purpose: Tumor cells are known to express hypoxia-related proteins such as glucose transporter-1 (Glut-1). These hypoxia-induced changes may allow tumor cells to survive under sustained hypoxic microenvironments, and the surviving tumor cell under hypoxia may develop a more aggressive phenotype and so result in a poor prognosis. Materials and Methods: The Glut-1 expression was analyzed by immunohistochemistry, and its association with the prognosis was assessed in 60 patients with squamous cell carcinoma of the tongue.Results: The Glut-1 expression was diffuse with a membranous pattern, and the median percentage of Glut-1 positive tumor cells was 60% (range: 0.0∼90.0%). A high Glut-1 expression (the percentage of positive tumor cells ≥ the median value, 60%) was associated with the location of primary lesion, lymph node metastasis status and disease stage (p〈0.05).Theexpression of Glut-1 was correlated with the Ki-67 expression (r=0.406, p=0.001). Microvessel density, as represented by CD31 staining, was also correlated with the Glut-1 expression although its significance is weak (r=0.267, p=0.039). On the univariate analysis, the group with a high Glut-1 expression showed poorer overall survival than the group with a low Glut-1 expression (p〈0.05). However, the Glut-1 expression failed to show any independent prognostic significance on the multivariate analysis.Conclusion: The expression of Glut-1 may be useful for predicting the prognosis and determining the treatment strategy for the management of squamous cell carcinoma of the tongue. (Cancer Res Treat. 2007;39:109-115)