• 한국통신학회논문지
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• 제29권6A호
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• pp.600-606
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• 2004

본 논문에서는 인터리빙 딜레이 다이버시터 기법을 제안하고 이를 다중 코드 WCDMA 시스템에 적용한다. 제안 시스템에서의 딜레이 다이버시터 기법은 인터리빙 기법을 적용하여 잡음과 페이딩의 영향을 감쇄시켜 시스템 성능을 개선하고 인터리빙된 신호와 인터리빙 되지 않은 신호를 서로 다른 시간 간격을 두어 전송시켜 시간 다이버시터 이득을 얻으며 송신단에서 우너신호의 재전송 횟수를 적절히 증가시킴에 따라 수신 다이버시터이득을 효과적으로 얻을 수 있도록 한다. 또한 다수의 안테나 중 채널 상황이 좋은 안테나만을 선택하여 신호를 전송하는 안테나 선택 기법을 적용하여 제한된 전력을 효율적으로 사용하는 기법을 제안하였다. 컴퓨터 시뮬레이션을 통해 제안된 시스템이 기존 시스템에 비해 2dB 이상의 성능개선을 나타냄을 확인하였다.

• 한국조경학회지
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• 제33권4호
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• pp.1-10
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• 2005

Recently, as urban landscape is growing in importance, urban landscape planning is being actively performed. for this purpose, classification of the urban landscape is definitely required. Therefore, this research focuses on classifying urban landscape in Daejeon metropolis by dividing the urban land use pattern. This results are as follows. 1. Urban land use pattern is divided into 20 classes. The residential, commercial and industrial areas, the old market and the bus terminal are evaluated negatively, whereas the areas of school, water reservoir, neighborhood park and train station are appreciated as being positive in landscape characters. 2. As a result of a cluster analysis, urban landscape has five different landscape types. These are: landscapes of medium diversity lacking green area, landscapes of high diversity lacking green area, landscapes rich in green area and with medium diversity, landscapes rich in green area and with high diversity, and landscapes rich in green area and with low diversity. 3. In landscape characters of beauty and harmony, landscapes rich in green area and with medium diversity are more positively evaluated than those rich in green area and with low diversity. This point should be taken into account for planning the urban landscape.

• 대한전자공학회논문지TC
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• 제42권1호`
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• pp.29-37
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• 2005

다중반송파 변조방식의 주요한 문제점중의 하나는 도플러 천이에 의한 주파수 옵셋에 민감하다는 점이다. 주파수 옵셋은 다중반송파 변조된 신호의 주파수 중첩으로 인한 반송파간의 간섭을 야기시킨다. 그러나 채널변화에 따른 도플러 천이는 또 다른 다이버시티 이득을 제공할 수 있는 요소가 될 수 있다. 본 논문에서는 변형된 다중반송파 코드분할 다중접속(multicarrier CDMA) 시스템을 제안함으로써 다중경로 다이버시티외에 도플러 다이버시티를 이용할 수 있게 하였다. 이를 위하여 이동 무선채널을 독립적인 시간 및 주파수 페이딩 채널로 분해하고 시간 다이버시티를 이용하는 레이크 수신기를 주파수영역으로 확장하므로써 다중경로 및 도플러 다이버시티 이득을 동시에 얻을 수 있도록 하였다.

• Journal of Forest and Environmental Science
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• 제32권4호
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• pp.367-376
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• 2016

Urban greenery is an important component of urban environment and is fast gaining prominence especially in the developing countries. The destruction of urban trees has resulted to the degradation of the environment, thus the introduction of green Kumasi project by Kumasi Metropolitan Assembly, Ashanti Region of Ghana. The composition and diversity of urban trees gives rise to adequate management and monitoring, thus an inventory of urban trees of the Metropolis was conducted to document complete information on its density, diversity, composition and distribution. A total tree population of 1,101 was enumerated in the principal roads of the Metropolis. The ten most encountered tree species accounted for 61.04% of all the individual tree populations with Mangifera indica being dominant. The dominant families: Fabaceae, Moraceae and Arecaceae constitute 38.57% of the tree population. Diversity of the tree species was very high. The minimum diversity criteria were met on analysis of the diversity of this population. The proportion of exotic species was high with 65.71% of the trees belonging to the introduced species. It is recommended that greater emphasis should be placed on the planting of indigenous trees in future tree planting exercise.

• 반도체디스플레이기술학회지
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• 제14권2호
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• pp.9-16
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• 2015

In this paper, selection criterions on selection diversity are researched. The diversity is applied to the multiple antenna system based on wireless access in vehicular environment (WAVE) standard for rapid varying channel. Least squares (LS) based decision feedback equalizer (DFE) are used for channel equalization. Received signal is regenerated by means of the decision feedback path. In the selection diversity, the regenerated signal as well as the received signal is selected according to selection criterion. The decision feedback algorithm can follow the fast speed of WAVE fading channel. To control the tracking speed of the time-varying channel, simple low pass filter is used. Finally, the estimated channel value recovers the distorted payloads. Signal power before automatic gain control (AGC) in analog stage can be used as a selection criterion. In the digital stage, signal power after AGC, noise power after AGC, signal to noise ratio after AGC and cross-correlation method can be used as selection criterions. According to the simulation results, the performance of the selection diversity is improved in comparison with that of the combining diversity for the WAVE fading channel.

• The Plant Pathology Journal
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• 제29권4호
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• pp.435-439
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• 2013

Rice blast fungus, Magnaporthe oryzae, inflicts serious damage to global rice production. Due to high variability of this fungal pathogen, resistance of newly-released rice cultivars is easily broken down. To understand the population structure of M. oryzae, we analyzed the genetic diversity of the Korean population using multilocus microsatellite typing. Eleven microsatellite markers were applied to the population of 190 rice isolates which had been collected in Korea for two decades since the 1980's. Average values of gene diversity and allele frequency were 0.412 and 6.5, respectively. Comparative analysis of the digitized allele information revealed that the Korean population exhibited a similar level of allele diversity to the integrated diversity of the world populations, suggesting a particularly high diversity of the Korean population. Therefore, these microsatellite markers and the comprehensive collection of field isolates will be useful genetic resources to identify the genetic diversity of M. oryzae population.

• 한국전자파학회논문지
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• 제11권3호
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• pp.403-409
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• 2000

본 논문에서는 마이크로셀 환경에서 상향경로(Up- Link)에서의 면파 다이버시티 기법 적용에 필요한 파라미 터인 교차편파 변별도(cross polarization discrimination: XPD). 신호상관계수(signal correlation coefficient:$\rho$). 수신선호 감쇠값(received signal decrease) 등을 측정을 통하여 분석하였다. 1.9 GHz에서 측정되었으며 빌딩밀집지역, 주택밀집지역. 상권지역, 학교지역 등 서울 도심지역의 여러 환경에서 자료들을 수집하였다. 자료분석 결과 교차편파 변별도(XPD)는 환경에 따라 6~11 dB 측정되었고, 신호상관계수($\rho$)는 0.7보다 낮았으며, 수신선호 감쇠값은 3dB보다 작았다. 공간 다이버시티와 성능비교 분석결과. 편파 다이버시티 이득이 환경에 따라 2-5 dB 정도 높은 것으로 분석되었다. 그러므로, 편파 다이버시티 기법은 마이크로 셀 환경에서 효과적으로 사용될 수 있는 다이버시티 기법으로 판단된다

• Journal of Ecology and Environment
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• 제40권2호
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• pp.84-88
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• 2016

To understand the effects of habitat characteristics on the genetic diversity of Persicaria thunbergii, three sites of different environmental conditions in a water system were surveyed. Site A was the closest to the source of the water system, and there was a dam between sites A and B. Site C is located on the lowest downstream in the water system. Vegetation survey of four quadrats at each site was performed, and soil samples were collected for physicochemical analysis. Random amplification of polymorphic DNA (RAPD) analysis of ten P. thunbergii individuals at each site was conducted to calculate population genetic diversity and genetic distance among populations. Soil was sterile sand at site A, whereas loamy soil at sites B and C. A pure stand of P. thunbergii appeared at site A, while other species occurred together (such as Humulus japonicus and Phragmites australis) at sites B (Shannon-Wiener index; $H_B=0.309$) and C ($H_C=0.299$). Similar to the species diversity, genetic diversity (Nei's gene diversity; h) within population of site A ($h_A=0.2381$) was relatively lower than sites B ($h_B=0.2761$) and C ($h_C=0.2618$). However, site C was separated from sites A and B in genetic distance rather than the geographical distance (Nei's genetic distance; A~B, 0.0338; B~C, 0.0685; A~C, 0.0833).

• Ocean and Polar Research
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• 제34권1호
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• pp.19-28
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• 2012

In order to understand the spatial distribution of picocyanobacterial diversity during the summer in the northern East China Sea (ECS), their abundance and genetic diversity were investigated using flow cytometry and barcoded amplicon pyrosequencing of 16S-23S internal transcribed spacer sequences. Synechococcus abundance was high, with a range of $0.2{\times}10^5$ to $1.8{\times}10^5$ cells $ml^{-1}$. However, Prochlorococcus were found only in the eastern part of the studied area, showing a marked variation among stations [range of n.d. (not detected) to $3.3{\times}10^4$ cells $ml^{-1}$]. Eleven Synechococcus clades and five Prochlorococcus ecotypes were found to have a proportion higher than 1% among picocyanobacterial sequences, indicating high picocyanobacterial diversity in the ECS. The picocyanobacterial compositions were markedly different among stations, as well as among depths. Inflow of the Tsushima Warm Current and Changjiang diluted water was of primary importance in determining picocyanobacterial lineage diversity in the studied area. In addition, light intensity and nutrient conditions also appeared to be important in the vertical and horizontal distribution of picocyanobacterial diversity.

• Journal of Communications and Networks
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• 제13권3호
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• pp.240-249
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• 2011

Cooperative diversity protocols have attracted a great deal of attention since they are thought to be capable of providing diversity multiplexing tradeoff among single antenna wireless devices. In the high signal-to-noise ratio (SNR) region, cooperation is rarely required; hence, the spectral efficiency of the cooperative protocol can be improved by applying a proper cooperation selection technique. In this paper, we present a simple "cooperation selection" technique based on instantaneous channel measurement to improve the spectral efficiency of cooperative protocols. We show that the same instantaneous channel measurement can also be used for relay selection. In this paper two protocols are proposed-proactive and reactive; the selection of one of these protocols depends on whether the decision of cooperation selection is made before or after the transmission of the source. These protocols can successfully select cooperation along with the best relay from a set of available M relays. If the instantaneous source-to-destination channel is strong enough to support the system requirements, then the source simply transmits to the destination as a noncooperative direct transmission; otherwise, a cooperative transmission with the help of the selected best relay is chosen by the system. Analysis and simulation results show that these protocols can achieve higher order diversity with improved spectral efficiency, i.e., a higher diversity-multiplexing tradeoff in a slow-fading environment.