• Journal of electromagnetic engineering and science
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• 제4권3호
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• pp.128-136
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• 2004

In this paper,. with the aim of achieving the expected performance improvement for a polarization diversity system, we analyzed two-branch polarization diversity at the receiving end of a mobile link which a transmitter emits circularly polarized wave. In this analysis, to calculate the correlation coefficient considered by XPD(cross polarization discrimination) between the two received signals, a simple theoretical model of circular polarization diversity is adopted. From the analysis results, it is clearly seen that the correlation coefficient of circular polarization diversity evaluated by the XPD is less than that of conventional linear polarization diversity. And also, we designed and implemented a circular polarization diversity system with micro-strip antenna. By using the circular polarization diversity system, we analyzed the measured data in indoor NLOS(Non-Line-Of-Sight) environments. From this analysis results, it is also clearly seen that the diversity effect of circular polarization diversity system shows better performance compared to the conventional linear diversity system by about 3 dB high.

• 전기학회논문지P
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• 제60권4호
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• pp.200-205
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• 2011

In multipath fading channel, diversity is essential to mitigate the impairments. In this paper, we have proposed the angle diversity scheme called ATTD(Angle Time Transmit Diversity) instead of Alamouti's STTD(Space Time Transmit Diversity) and have analyzed the performance of the proposed scheme when signal powers caused by the transmission to different angles are different. Based on it, we have measured the wireless vector-channel in the urban area, which has lots of high-story buildings, using the data collected from the 8 by 4 smart array antenna system that we made. According to the measured data, the received signals from different angles have different signal powers. Our performance analysis results show that the proposed scheme has better performance than the space diversity scheme when the received path signal power is at least -7dB compare to the strongest path signal power.

• 한국컴퓨터정보학회논문지
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• 제20권11호
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• pp.77-88
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• 2015

This study attempts to investigate the effect of team diversity on individual creativity and team members' creative activities such as exploration and exploitation. We have garnered 40 team data from 249 respondents who have been participating in the team learning activities during semester in a private university. They were asked by instructor to show their creativity, and exploration and exploitation activities. The 40 teams were made up of team diversity factors such as study hour and leisure activity. We used a multilevel analysis to analyze the effects of team diversity factors on team member's creativity, and exploration and exploitation. Results showed that in general, team diversity factors like study hour and leisure activities have significant effects on the individual creativity, and exploration and exploitation. Practical implications represent that teams need to be organized considering the team diversity factors in order to improve team member's creativity, and their exploration and exploitation activities.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권6호
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• pp.989-1005
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• 2010

Cooperative diversity is a technique with which a virtual multiple antenna array is established among the single antenna users of the wireless network to realize space diversity. Signal space diversity (SSD) is a bandwidth-efficient diversity technique, which uses constellation rotation and interleaving techniques to achieve diversity gain. A new cooperative diversity scheme with rotated constellations (RCCD) is proposed in this paper. In this scheme, data are modulated by using a rotated constellation, and the source and the relays transmit different components of the modulated symbols. Since any one of the components contains full information of the symbols, the destination can obtain multiple signals conveying the same information from different users. In this way, space diversity is achieved. The RCCD scheme inherits the advantage of SSD - being bandwidth-efficient but without the delay problem of SSD brought by interleaving. The symbol error rate of the RCCD scheme is analyzed and simulated. The analysis and simulation results show that the RCCD scheme can achieve full diversity order of two when the inter-user channel is good enough, and, with the same bandwidth efficiency, has a better performance than amplify-and-forward and detect-and-forward methods.

• 한국언론정보학보
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• 제63권
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• pp.76-100
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• 2013

이 연구는 디지털 융합 미디어 발전에 따라 변화하는 문화 환경을 조명함으로써 문화다양성을 개념을 재정립하고 분석프레임을 제시하는 것이 목적이다. 지금까지의 많은 연구들은 미디어다양성과 문화다양성이 매우 혼란스럽게 사용하고 있으며, 이로 인하여 문화다양성에 대한 개념이 제대로 정립되지 못하고 있는 실정이다. 커뮤니케이션학 분야에서는 미디어다양성에 대한 분석이 경제적 계량과 콘텐츠의 수량 측정을 크게 벗어나지 못함으로써 콘텐츠의 실질적인 내용인 문화의 다양성을 측정하는 데는 한계가 있다. 따라서 이 연구는 문화다양성 분석을 위해서 디지털 융합 미디어 이용문화를 메타문화로 정의하였다. 그리고 이 메타문화에 기반하여 나타나는 문화다양성을 미디어 활동의 다원성, 문화적 표현의 다양성, 문화 확산의 다양성 그리고 문화적 인지의 다양성으로 분류하여 분석하였다. 네 가지 범주가 각각 포함하고 있는 측정변인들은 디지털 융합 미디어 환경에서 문화다양성의 양태들을 밝혀낼 수 있는 요인들이다. 이 요인들에 대한 분석은 문화다양성을 보호하기 위한 정책 방향을 수립하기 위한 기준들이다. 문화다양성 정책의 궁극적인 목적은 메타문화 환경에서 문화공유지를 구축하는 것이다.

• 한국토양비료학회지
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• 제49권2호
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• pp.144-156
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• 2016

Soil is a dynamic biological system, in which it is difficult to determine the composition of microbial communities. Knowledge of microbial diversity and function in soils are limited because of the taxonomic and methodological limitations associated with studying the organisms. In this review, approaches to measure microbial diversity in soil were discussed. Research on soil microbes can be categorized as structural diversity, functional diversity and genetic diversity studies, and these include cultivation based and cultivation independent methods. Cultivation independent technique to evaluate soil structural diversity include different techniques such as Phospholipid Fatty Acids (PLFA) and Fatty Acid Methyl Ester (FAME) analysis. Carbon source utilization pattern of soil microorganisms by Community Level Physiological Profiling (CLPP), catabolic responses by Substrate Induced Respiration technique (SIR) and soil microbial enzyme activities are discussed. Genetic diversity of soil microorganisms using molecular techniques such as 16S rDNA analysis Denaturing Gradient Gel Electrophoresis (DGGE) / Temperature Gradient Gel Electrophoresis (TGGE), Terminal Restriction Fragment Length Polymorphism (T-RFLP), Single Strand Conformation Polymorphism (SSCP), Restriction Fragment Length Polymorphism (RFLP) / Amplified Ribosomal DNA Restriction Analysis (ARDRA) and Ribosomal Intergenic Spacer Analysis (RISA) are also discussed. The chapter ends with a final conclusion on the advantages and disadvantages of different techniques and advances in molecular techniques to study the soil microbial diversity.

• 농촌계획
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• 제13권2호
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• pp.1-5
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• 2007

Shannon and Simpson indexes are used for species diversity analysis of ecosystem. In species diversity analysis of ecosystem, not only frequency of each species but also survey size have to be considered. In this study, total information composed with knowledge and ignorance was suggested as a species diversity analysis method for ecosystem survey. To apply developed method, flora in the Sangachun river valley was sampled with 19 sites and 198 species. In applying results, Shannon index shows more reasonable results than Simpson index by the variance of sample size but has difficulties of determining the relation of surveying species number and sample site number. Suggested total information can overcome this difficulty by the relation of knowledge and ignorance.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.609-612
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• 2003

For combating multipath fading in wireless radio environment, diversity schemes is useful. In this paper, for performance improvement of polarization diversity system, we analyzed a two-branch polarization diversity at the receiving end of a mobile link when the transmitter emits a circularly polarized wave. And In order to calculate the correlation coefficient considering the XPD(cross polarization discrimination) between the received signals for the two diversity branches, a simple theoretical model of circular polarization diversity is adopted and calculate correlation coefficient. From the analysis results, it is seen that the correlation coefficient of circular polarization diversity evaluated by the XPD is less than that of vertical polarization diversity. And also, we designed and fabricated circular polarization diversity system with microstrip antenna. we analyzed data measured in indoor NLOS environment using fabricated circular polarization diversity system. From the measurement results, it is clearly seen that the diversity effect of circular polarization diversity system is higher 3dB than vertical polarization diversity system.

• Journal of electromagnetic engineering and science
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• 제6권4호
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• pp.222-228
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• 2006

In this paper, the performance of a multiuser diversity system combined with a multi-element transmit antenna system is analyzed under the assumption of independent Rayleigh fading. A measure of system .level performance is an average channel capacity as a function of the number of users and antennas. Average channel capacity is obtained from the instantaneous signal-to-noise ratio(SNR) distribution combined by both transmit diversity(TD) at each link and multiuser diversity at system level. Numerical results show that closed-loop antenna techniques provide an additional gain with multiuser diversity system due to array gain, even though space diversity gain reduces multiuser diversity gain. On the other hand, the space-time block coding(STBC) that provides full order space diversity gain only has a destructive influence on multiuser diversity.

• Plant Resources
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• 제8권3호
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• pp.293-299
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• 2005

This study used RAPD markers to assume genetic diversity and variation in selected populations of Hovenia dulcis var. koreana. Ratio of polymorphic RAPD markers were 93.4% in selected populations of Hovenia dulcis Thunb., difference of genetic structure among populations and within populations showed 16.45%, 83.55%, respectively in amount of total genetic variation of 4 populations. Total gene diversity($H_T$) that show genetic diversity appeared 0.313 and coefficient of gene differentiation($G_{ST}$) that compare genetic differentiation of populations appeared 0.1645, analysis of AMOVA for variation among populations and within populations was significantly different (P<0.001). Genetic diversity of whole populations showed that 12.44% difference among population and 87.56% difference within populations. As a result, difference within populations was larger than difference among populations in genetic diversity. Nei's genetic distance and cluster analysis appeared that mean genetic distance among populations was 0.076, thus dividing two main groups and geographic relationship did not show in populations.