• 한국통신학회논문지
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• 제35권1A호
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• pp.62-70
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• 2010

본 논문에서는 위성-지상 통합(hybrid/integrated)망에서 멀티미디어 방송 서비스를 효율적으로 제공하도록 기여할 수 있는 여러 가지 다이버시티 방식에 대한 성능을 비교 분석한다. 시공간 부호(space-time codes)는 부가적인 대역폭 요구 사항 없이도 다중경로 환경에서 다이버시티 이득을 얻을 수 있는 효율적인 방식이다. 위성시스템에서 시공간 부호와 오류정정부호를 적절히 결합하여 지상 중계 장치와의 협동 다이버시티 이득 구현이 가능함이 제안되어 왔다. 본 논문에서는 이러한 선행 연구 결과를 바탕으로 하여, 다양한 시공간부호 및 오류정정 부호의 결합 방식을 제안하고 이에 따른 성능 분석 결과와 장단점등을 제시하여, 향후 시스템 구현에 도움이 될 수 있도록 한다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2008년도 추계학술대회
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• pp.103-105
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• 2008

차세대 양방향데이터방송 (BIFS: BInary Format for Scenes) 서비스에서는 하향링크(downlink) 데이터 전송률에 상응하는 높은 상향링크(uplink) 데이터 전송률이 요구되고 있다. 이에 무선 전송 채널의 한정된 자원 환경 속에서 상향링크 전송용량 증대를 위한 주파수 효율성 제고 기술의 필요성이 대두되고 있다. 본 논문에서는 차세대 양방향데이터방송을 위한 다중 모바일(mobile) 사용자의 클러스터(cluster) 기반 상향링크 협동 다이버시티(cooperative diversity) 기법을 제안한다. 제안된 기법은 하나의 단일 안테나(single antenna) 방송 기지국과 다수의 단일 안테나 모바일 사용자가 있는 상향링크 시분할다중접속 (TDMA: Time Division Multiple Access) 시스템에서 데이터 지연허용(delay-tolerant)에 따라 클러스터를 구성하고 제곱 다이버시티 차수(square diversity order)의 협동 프로토콜(cooperative protocol)을 통해 높은 공간다이버시티 이득(spatial diversity gain)을 얻는다. 또한, 비대칭(asymmetric) 무선 채널 환경에서 공정성(fairness)을 보장한다.

• Journal of Ecology and Environment
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• 제33권2호
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• pp.115-120
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• 2010

The Asian cultural landscape is a mirrored ecosystem of great complexity, formed by the interaction of man and nature, coupled with a host of ecological processes. The human dependencies on and environmental adaptation of the bio-organisms and the surrounding landscape constitute the typical cultural landscape. Islands are a good example of a cultural landscape, and each mosaic pattern of marine and coastal ecosystems reflects bio-cultural diversity. Along with land-use patterns, wise use of biological organisms and indigenous knowledge has expanded to islands in the Asia-Pacific region in several ways (sea current and human impact, etc.). Loss in biodiversity and landscape diversity as well as cultural diversity owing to global warming and rapid urbanization are emerging issues for island ecosystems all over the world. In order to sustain the historical coexistence between man and natural systems, we ecologists must continue to search for a holistic solution for academic consilience. In this paper, I present the vision and practical characteristics of island ecology with a view toward the conservation of the traditional landscape and bio-cultural diversities in the seascape.

• 환경생물
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• 제17권3호
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• pp.279-284
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• 1999

토양으로부터 직접 추출한 DNA를 cross hybridization하는 방법을 통해서 서로 다른 토양 환경 간에 미생물 군집의 유전형적 유사성과 상대적 다양성을 비교하였다. 그 결과 소나무삼림토양이 다른 토양에 비해 상대적 다양성이 높은 것으로 밝혀졌으며, 경작지, 나지, 초지, 신갈삼림 순으로 다양성 정도를 나타내었다. 또한 유전형적 유사성의 정도에 따른 집괴 분석 결과 소나무삼림과 경작지 토양, 신갈나무삼림과 초지 토양 그리고 나지 등 세 부류로 구분되었다.

• 한국멀티미디어학회논문지
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• 제11권12호
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• pp.1697-1705
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• 2008

Several studies made for wireless mesh networks aim to optimize the capacity for wireless networks. Aside from protocol improvements, researches were also done on the physical layer particularly on modulation techniques and antenna efficiency schemes. This paper is concerned with the capacity improvements derived from using spatial diversity with smart adaptive array antennas. The use of spatial diversity, which has been widely proposed for use in cellular networks in order to lessen frequency re-use, can be used in mesh networks both to minimize co-channel interference (CCI) and enable multiple transmissions. This paper aims to study the capacity region and bounds in using smart antennas for single-channel multi-radio systems in relation to the number of spatial diversity or sectors as defined by the beam angle $\beta$.

• 한국어교육
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• 제28권4호
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• pp.245-271
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• 2017

This study aimed at investigating the lexical diversity in the "Frog Story" narratives of Korean-Chinese bilingual children. Six bilingual speakers of Korean children- four boys and two girls- were audio recorded as they produced narratives based on pictures from the Mercer Mayer book "Frog, where are you?" The order of narration was counterbalanced. The vocabularies from narratives were analyzed by type, token, TTR (type-token Ratio) and D value using the CLAN (Computerized Language Analysis) program. The findings showed that the pattern of lexical diversity in Korean is similar with the Chinese, but the TTR and D value of Chinese still remain low in comparison with those of Korean. In addition, Korean language seems to have significant influence on Chinese in the language usage pattern and vice versa.

• Journal of Ecology and Environment
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• 제47권4호
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• pp.177-186
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• 2023

Background: Inner Mongolia, desertification is happening due to climate change and land use alterations. In order to evaluate desert restoration effectiveness, this study compares number of species and species diversity in restored (with planted trees), unrestored area, and the reference ecosystem (Ref-E, typical steppe and woody steppe). Results: The Ref-E had the most plant species (64 taxa), while the unrestored area had the fewest (5 taxa). Among restored areas (restored in 2012, 2008, 2005), older restoration sites had more species (18-42). Similarly, species richness (3.93-0.41) and diversity (1.99-0.40) were highest in the Ref-E and lowest in unrestored areas, with older restored sites having higher values. Conclusions: More plant species and diversity in older restoration areas suggest progress toward ecosystem stabilization, approaching the Ref-E. Therefore, tree planting in Inner Mongolia's Hulunbuir semi-arid desert is a successful restoration effort.

• 농촌계획
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• 제16권4호
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• pp.117-129
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• 2010

This study is to make value estimating system to valuate prototype landscape of rural and to derive itemized importance to select priority preservable object The results of the study are summarized as follows, It is examined value estimating standard by analyzing prototype landscape related previous study, law and order. Also, It is derived conclusive prototype landscape value estimating system by doing attribute assessment of preserving objects while surveying the site and interviewing professionals, Value estimating system is classified into five items of physical value which are integration, harmony, diversity, symbolism and aesthetics, The historical-cultural value are divided into four categories which are religious value, originality, historicity and scarcity, The communal values are divided into three categories which are sociality, continuing and regional locality and also divided into three categories which are rarity, primitiveness and diversity as the ecological value, Relative priority of prototype landscape value estimating system result is derived as historical-cultural value as the superior position and physical value, communal value and ecological value as the priority order. In the subordinate, historical categories are derived to be the most valuable and originality, symbolism, integration, regional locality, continuing, harmony, aesthetics, religious value, primitiveness, diversity of physical values and diversity of ecological value in order of the priority assessment The results of the study have the meaning of practical use in prior selection and preservation plan of preserving prototype landscape as practical alternative plan for systematical preservation of damaging prototype landscape.

• 환경영향평가
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• 제20권6호
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• pp.845-856
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• 2011

In order to establish fundamental data for stream restoration and environmental flow, we investigated inhabitation and species diversity of fish to substrate size in the typical streams of Geum River Basin. Field monitoring including fish sampling was conducted from October 2007 to October 2009. Substrate size was determined according to six different : silt (Si), sand (Sa), fine gravel (Fg), coarse gravel (Cg), cobbles (Co) and boulders (Bo). A total number of fish caught in the 18 sites was 7,649 representing 10 families 50 species, and Si, Sa, Fg, Cg, Co and Bo stations occupied 30, 29, 38, 30, 27 and 17 species, respectively. The most frequently found species in number was pale chum (Zacco platypus, 29.7%, n=2,275) followed by Z. koreanus (22.5%, n=1,720) in total stations. Biological diversity with increase of substrate size from the dominance of part species showed higher values as dominance index, lower and diversity, richness and evenness index. Index of biological integrity (IBI) and qualitative habitat evaluation index (QHEI) scores decreased with increase of substrate size. Therefore, it is necessary to make an effort on stream rehabilitation with evaluation of physical habitat condition by indicator species in order to maintain biodiversity and perform ecological restoration.

• Journal of Ecology and Environment
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• 제42권3호
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• pp.111-119
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• 2018

Background: Juniperus chinensis L. populations are distributed locally on several areas including coastal cliffs which are difficult to access in the central eastern Korea. Wild populations inhabit relatively barren environments such as rocky areas and cliffs, which are very sensitive to even minor environmental disturbances including artificial interventions and natural disturbances, and thus demonstrate great fluctuations in the population size and density. This study aims to analyze the genetic diversity, differentiation, and genetic structure of each population in order to provide useful data required to establish a substantial conservation strategy of J. chinensis. Results: The genetic diversity of J. chinensis at the population level (P = 78.7%, h = 0.282, S.I. = 0.420) was somewhat higher compared with those measured in the same genus, Juniperus. The genetic differentiation degree among nine populations established naturally in central eastern Korea was 11.50% and that among sub-populations within the same area was 5.52%. On the other hand, genetic variation of individuals within the populations was 82.93%. But frequency of the main allele was different among loci. In particular, fixation of allele frequency and occurrence of rare allele in the highly isolated population suggest a likelihood that genetic drift would occur in populations of this plant. As the result of analysis on the genetic structure of nine populations, nearby populations and isolated populations tended to form separate clusters from each other as the hypothetical number of clusters (K) increase. Conclusions: This result implies that if the population size of J. chinensis is reduced due to environmental change and artificial and/or natural disturbances in the future, it could affect negatively on the genetic diversity of the plant species. In order to maintain and conserve genetic diversity of J. chinensis, ecological network, which can help genetic exchange among the local populations, should be prepared, and conservation strategies in situ as well as ex situ are also required with continuous monitoring.