히스토그램 기반 코드 영역 보상 기법을 적용한 W-CDMA 기지국용 CFR 알고리즘

장형민,이원철,Chang, Hyung-Min,Lee, Won-Cheol 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.12c

이동통신 기지국 시스템에서 송신 신호의 PAR 성능을 (peak-to-average power ratio) 개선함으로써 범용 전력 증폭기의 사용이 가능하게 되며, 이로 인해 전체적인 기지국 비용의 절감을 기대할 수 있다. 일반적으로 PAR 값을 줄임으로 인해 기지국 송신신호의 인근 대역 간섭 제한 성능을 나타내는 ACLR이나 (adjacent channel leakage ratio) 품질을 나타내는 EVM이나 (error vector magnitude) PCDE 성능의 (peak code domain error) 열화를 발생시킨다. 본 논문에서 이러한 문제점을 해결하기 위하여 필터링 기반의 CFR 방식인 (crest factor reduction) FDCFR 알고리즘을 (filter-dependent CFR) 소개하며, 히스토그램 기반 코드 영역 보상(HBWCDC; histogram based waterfilling code domain compensation)기법을 제안한다. 본 논문에서 제안한 CFR 알고리즘은 PAR 감소뿐만 아니라 앞서 언급한 ACLR, EVM 및 PCDE등의 성능 열화를 방지한다. This paper proposes a novel crest factor reduction (CFR) algorithm to be deployed on WCDMA basestation. Generally speaking, it is well described that the reduction of peak-to-average ratio (PAR) yields the possibility of using low cost power amplifier such that the basesation becomes economic However, the simple reduction of PAR could degrade the signal quality measured by either peak code domain error (PCDE) or error vector measurement (EVM), and the level of channel interference constrained by adjacent channel leakage ratio (ACLR). Regarding these imperfections, this paper introduces an effective CFR algorithm in which the function of filter-dependent CFR (FDCFR) incorporated with the histogram-based waterfilling code domain compensation (HBWCDC) carries out. To verify the performance of the proposed CFR technique, substantial simulations including comparative works are conducted with obeying W-CDMA basestation verification specification. To exploit the superiority, the performance of the proposed method is tentatively compared with that associated to the simple memoryless clipping method and the memory-required filter-dependent clipping method.

USRP를 이용한 WPAN 기반 기계 상태 모니터링 및 제어용 무선통신 시스템

장형민(Chang Hyung Min),주형종(Ju Hyoung Jong),조장(Zhoa Zhuang),이원철(Won Cheol Lee) 한국통신학회 2012 한국통신학회 학술대회논문집 Vol.2012 No.6

일 산촌 지역의 음주 행태 변화- 6년 추적 조사 -

이유라(You-Ra Lee),신정호(Jong-Ho Shin),민성호(Seong-Ho Min),김태희(Tae-Hui Kim),김민혁(Min-Hyuck Kim),장형민(Hyung-Min Chang),박기창(Ki-Chang Park),안정숙(Joung-Sook Ah),전영안(Yong-An Jeon),장지숙(Jee-Sook Jang) 한국중독정신의학회 2005 중독정신의학 Vol.9 No.1

Objectives:This study was designed to find out the changes of alcohol use behavior and it’s attributing factors through two surveys conducted in 1998 and 2004 in a rural community. Methods:We selected 116 problem drinkers and 116 matched non-problem drinkers among 480 men of the first survey. We surveyed basic epidemiologic data and alcohol use behavior with several questionnaires. Results:The results were as follows : 1) Drinking amount and frequency decreased with increasing age. 2) More than half among previous problem drinkers did not show any significant change in their alcohol use behavior. 3) Most of previous non-problem drinkers maintained their past alcohol use behavior. 4) Continuous problem drinkers had larger amount of past alcohol drinking than no more problem drinkers. They had lower scores on awareness of negative consequence, higher scores on drinking for coping strategy of Alcohol Effects Questionnaire (AEQ) and higher scores on drinking urge to relieve hangover of the Severity of Alcohol Dependence Questionnaire (SADQ) than no more problem drinkers. 5) Continuous problem drinkers showed more smoking and earlier drinking than continuous non-problem drinkers. 6) Continuous problem drinkers became poorer than no more problem drinkers. Conclusions: Continuous problem drinking pattern was associated with larger amount of past alcohol drinking, higher drinking frequency, higher drinking urge to relieve hangover, higher use of drinking for coping strategy and less awareness of negative consequence.

IEEE 802.15.4m 기반 IAN 환경에서의 기계 상태 모니터링 및 제어 정보 전달에 적합한 WPAN 시스템에 관한 연구

장형민(Hyung Min Chang),최한나(Han Nah Choi),이원철(Won Cheol Lee),최동수(Dong Soo Choi),김진오(Jin Oh Kim) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

In order to transmit monitoring information and control signal, TVWS (TV White Space) which has better propagation characteristics rather than ISM band due to a low frequency, is applied to the IAN (Industry Area Network). In this paper, based on IEEE 802.15.4m which can use TVWS consisting of lots of sub-channels, this paper analyses the performances of WPAN such as the number of simultaneously operating TVBDs (TV Band Devices) and their transmission powers obeying the technical regulations described by FCC or ECC in industrial area.

유사 선형 위상 특성을 갖는 IIR 필터군을 이용한 Wibro용 디지털 상하향 변환 연구

장형민(Hyung-min Chang),이원철(Won-cheol Lee) 한국통신학회 2009 韓國通信學會論文誌 Vol.34 No.2C

OFDM 방식을 사용하는 Wibro(Wireless Broadband Internet) 시스템의 중계 과정에서 발생하는 지연 시간을 최소화하여 복조 과정에서 고려될 수 있는 심볼간 간섭 발생을 방지하기 위해 Wibro용 디지털 상하향 변환 과정의 전체 처리 지연 시간을 최소화하기 위한 방안이 필수적이다. 특히 디지털 처리단에서 적용되는 채널화 필터는 일반적으로 FIR 형태로 구성되지만 고도의 필터 특성을 위해 비교적 많은 수의 계수 값들을 요구하며, 이로 인해 과도한 처리 지연 시간을 발생한다. 이러한 문제점을 해결하기 위하여 본 논문에서는 기존 채널화 필터의 크기 응답을 최대한 보존하면서 안정성을 갖는 IIR 필터를 설계하는 방법과 IIR 필터 본연의 비선형적인 위상 특성 보정을 위해 전대역 통과 IIR 필터를 구성하는 기법을 소개하고 이 두 기법을 통합한 IIR 필터군을 제안한다. 또한 IIR 필터군이 갖는 비선형 위상 특성을 좀 더 개선하며, 처리 복잡도를 개선하기 위해 전체 IIR 필터군을 다상 필터 구조로 변환하는 방안을 제안한다. 본 논문에서 제안하는 IIR 필터군을 적용한 디지털 상하향 변환 구조는 전체 처리 시간을 단축할 수 있을 뿐 아니라 우수한 신호 품질을 유지하게 됨을 시뮬레이션을 통해 입증한다. The repeater for wireless broadband internet (Wibro) system using OFDM demands the short processing delay to eliminate inter-symbol interference resulted from the time delay greater than the guard time. Towards this, the total system delay of repeater is expected to be minimized as possible as it can without distorting signal quality. In general, the FIR-type of filter is commonly deployed as a channelization filter, but due to its large amount of coefficients for producing prerequisite filter response the excessive large time delay occurs. To withstand this problem, the paper proposes the method for designing IIR filter whose response almost identical to that of the original filter. Moreover, in order to linearize the phase response of the designed IIR filter, this paper also introduce the way of designing the all-pass filter to be cascaded works for linearizing phase response of the channelization as well as the de-channelization filter. To achieve the further improvement in linearization of the phase response and reduction of the overall complexity, this paper tries to transform the integrated IIR filter group into the structure in polyphase style. The computer simulation verifies that the integrated IIR filter group designed in this paper reveals the relatively short processing delay without harming the acceptible signal quality.

히스토그램 기반 코드 영역 보상 기법을 적용한 W-CDMA 기지국용 CFR 알고리즘

장형민(Hyung-min Chang),이원철(Won-cheol Lee) 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.11C

이동통신 기지국 시스템에서 송신 신호의 PAR 성능을 (peak-to-average power ratio) 개선함으로써 범용 전력 증폭기의 사용이 가능하게 되며, 이로 인해 전체적인 기지국 비용의 절감을 기대할 수 있다. 일반적으로 PAR 값을 줄임으로 인해 기지국 송신신호의 인근 대역 간섭 제한 성능을 나타내는 ACLR이나 (adjacent channel leakage ratio) 품질을 나타내는 EVM이나 (error vector magnitude) PCDE 성능의 (peak code domain error) 열화를 발생시킨다. 본 논문에서 이러한 문제점을 해결하기 위하여 필터링 기반의 CFR 방식인 (crest factor reduction) FDCFR 알고리즘을 (filter-dependent CFR) 소개하며, 히스토그램 기반 코드 영역 보상(HBWCDC; histogram based waterfilling code domain compensation)기법을 제안한다. 본 논문에서 제안한 CFR 알고리즘은 PAR 감소 뿐만 아니라 앞서 언급한 ACLR, EVM 및 PCDE 등의 성능 열화를 방지한다. This paper proposes a novel crest factor reduction (CFR) algorithm to be deployed on WCDMA basestation. Generally speaking, it is well described that the reduction of peak-to-average ratio (PAR) yields the possibility of using low cost power amplifier such that the basesation becomes economic. However, the simple reduction of PAR could degrade the signal quality measured by either peak code domain error (PCDE) or error vector measurement (EVM), and the level of channel interference constrained by adjacent channel leakage ratio (ACLR). Regarding these imperfections, this paper introduces an effective CFR algorithm in which the function of filter-dependent CFR (FDCFR) incorporated with the histogram-based waterfilling code domain compensation (HBWCDC) carries out. To verify the performance of the proposed CFR technique, substantial simulations including comparative works are conducted with obeying W-CDMA basestation verification specification. To exploit the superiority, the performance of the proposed method is tentatively compared with that associated to the simple memoryless clipping method and the memory-required filter-dependent clipping method.

분위기에서 Al-Mg합금의 SiO2에 대한 젖음실험의 타당성 고찰

장형민 ( Hyung Min Jang ),이창면 ( Chang Myeon Lee ),이준호 ( Joon Ho Lee ),이재훈 ( Jae Hoon Lee ),이재철 ( Jae Chul Lee ) 대한금속재료학회 ( 구 대한금속학회 ) 2009 대한금속·재료학회지 Vol.47 No.6

The effects that processing atmospheres and alloy composition have on the wetting characteristics of Al-Mg alloys on the SiO2 substrate were investigated by measuring the wetting angles. It was observed that the wetting behavior of the Al-Mg alloys on the SiO2 substrate vary depending on the Mg content of the alloys and atmospheres. The results showed that the contact angle decreases with increasing Mg content, angle is generally larger in the N2 atmosphere than in the Ar atmosphere. We discussed the validity of the results obtained from the wetting test on the basis of recent theories and the results observed from the actual penetration tests. (Received January 9, 2009)

실내 TVWS 무선통신을 위한 송신 전력 설정 실험에 관한 연구

윤덕원(Deok-won Yun),장형민(Hyung-min Chang),이원철(Won-cheol Lee) 한국통신학회 2013 韓國通信學會論文誌 Vol.38 No.10(네트워크)

전 세계적으로 디지털 TV 방송 서비스로의 전환에 대해 미래의 주파수 부족을 해결하기 위한 방안으로 우수한 전파 특성을 가진 TV 화이트 스페이스(White Space)에 대한 관심이 미국과 유럽을 중심으로 높아지고 있다. 본 논문에서는 이러한 실내 환경에서 TV 화이트 스페이스 대역을 이용하는 TVBD(TV Band Device)의 송신기가 DTV(Digital TV) 수신기에 미치는 간섭에 대한 실측 실험을 수행하였으며, 이와 병행하여 SEAMCAT툴을 이용한 몬테카를로 모의실험을 통해 통계적 간섭확률을 산출함으로써 실측 실험 결과와 비교분석을 수행하였다. 본 실측실험 및 모의실험 과정에서 주어진 DTV 수신환경과 각각의 송신 파라미터들은 FCC에서 규정한 TVBD 송신 규격에 준하여 설정하였다. 이를 기반으로 실내 환경에서 DTV 수신기와 TVBD 송신기 간의 거리에 따른 최적 공존을 위한 TVBD 송신 전력을 산출하였으며, 결론적으로 두 시스템이 상호 양립 가능한 기술기준을 확인하였다. To overcome a scarcity of radio resources to mobile broadband service, the usage of TV white space gains much attraction around the world. This paper carries out an interference analysis either by performing realistic experiments or by executing statistical Monte-Carlo simulation to exploit interference probability. The results obtained from experiments are compared to those from simulations in order to clarify the coexistence of utilization of TV band devices (TVBD) in indoor circumstances. Along the execution of our experiment in the presence of DTV receiver, we apply to a variety of transmission parameters proposed in FCC for TVBD. According to experimental and simulation works, the allowable transmission powers of TVBD systems are exploited for the plausible which are coexist on the first as well as the second adjacent frequency bands. Throughout results, it can conclude that TVBD systems can be coexisted via achieving proper transmission powers depending on the locations of themselves without showing harmful interference to DTV reception.

빌딩 내 스마트그리드 무선통신 최적화를 위한 경로손실 모델 분석

윤덕원(Yun Deok Won),장형민(Chang Hyung Min),이원철(Lee Won Cheol) 한국통신학회 2014 한국통신학회 학술대회논문집 Vol.2014 No.6

Research on Optimum Power Scheduling Method based on Real-time Electricity Price

Zhao Zhuang(조장),Chang Hyung Min(장형민),Ju Hyeong Jong(주형종),Lee Won Cheol(이원철) 한국통신학회 2012 한국통신학회 학술대회논문집 Vol.2012 No.2