• Journal of electromagnetic engineering and science
• /
• v.6 no.3
• /
• pp.189-195
• /
• 2006

In this paper, the derivation of the protection ratio for the digital microwave system with diversity is newly suggested for a basic guidance of initial planning for frequency coordination, and computational results are presented for an actual radio frequency band. The net filter discrimination has been also examined to see the effect of the adjacent channel protection ratio caused by adjacent channel interference. In addition, the protection ratios for the space or frequency diversity system are analyzed in terms of diversity improvement factors to find out an equivalent allowable noise-to-interference ratio (N/I) from degraded fade margin. According to results for 6.2 GHz system, with the space diversity of 25 m distance between antennas or the frequency diversity of ${\Delta}f/f=0.05$, under 64-QAM and 60 km at BER $10^{-6}$, the protection ratio can be greatly reduced in comparison to the non-diversity system. So, assuming that only the same protection ratio as the non-diversity system is kept, it is shown that the system with diversity may get more interference level of N/I allowing from 9.0 to - 5.9 dB or from 6.0 to - 4.3 dB for the space or frequency diversity. In consequence, it is concluded that the diversity system is more robust or tolerable for interferences or fades, which may play an important role in overcoming N/I to some extent.

• Journal of Forest and Environmental Science
• /
• v.27 no.3
• /
• pp.127-134
• /
• 2011

The purpose of the study was to assess and compare the diversity of plant species (trees, shrubs, herbs) of natural forest and plantations. A total of 52 plant species were recorded in the natural forest, of which 16 were trees, 15 were shrubs and 21 were herbs. On the contrary, 31 species of plants including 11 trees, 8 shrubs and 12 herbs were identified in plantation forest. Shannon-Wiener diversity index were 2.70, 2.72 and 3.12 for trees, shrubs and herbs respectively in the natural forest. However, it was 2.35 for tree species, 2.31 for shrub species and 2.81 for herb species in the plantation forest. Jaccard's similarity index showed that 71% species of trees, 44% species of shrubs and 43% species of herbs were same in plantations and natural forest.

• Korean Journal of Agricultural Science
• /
• v.48 no.4
• /
• pp.693-702
• /
• 2021

The aim of this study was to analyze the genetic diversity and distance of the Korean native black goat line. Thus far, this Korean native black goat line has not been studied intensively, especially in genetic diversity and relationship studies in comparison with other breeds. In total, eleven microsatellite (MS) markers were used to evaluate alleles from 391 Korean native black goats and foreign hybrid animals. The genetic diversity index was evaluated based on the allele distributions. Four Korean native black goat lines showed expected ranges of observed heterozygosity, expected heterozygosity, and polymorphism information content (PIC) values for use in genetic diversity research (0.509 - 0.643, 0.434 - 0.623 and 0.356 - 0.567). Lines from the Korean native black goat and foreign hybrid were clearly separated according to principal coordinates analysis (PCoA), phylogenetic tree and tended to be clustered in each Korean native black goat line. Thus, this study can be used for analyzing the genetic relationships between Korean native black goats and foreign breeds for line preservation and for fundamental information to determine breed improvement strategies.

• International Journal of Computer Science & Network Security
• /
• v.24 no.2
• /
• pp.95-100
• /
• 2024

Cyclic Delay Diversity (CDD) is a diversity scheme used in OFDM-based telecommunication systems, transforming spatial diversity into frequency diversity and thus avoiding intersymbol interference without entailing the receiver to be aware of the transmission strategy making the signal more reliable achieving full diversity gain in cooperative systems. Here the analyzation of the influence of CDD-SC scheme in Cognitive Radio Network (CRN) is done with the challenge of overcoming the complication called channel estimation along with overhead in CNR. More specifically, the closed-form expressions for outage probability and symbol error rate are divided under different frequencies among independent and identically distributed (i.i.d.) frequency selective fading channel model i.e., the signal is divided into different frequencies and transmitted among several narrow band channels of different characteristics. It is useful in the reduction of interference and crosstalk. The results reveal the diversity order of the proposed system to be mainly affected by the number of multipath components that are available in the CNR.

• Journal of Forest and Environmental Science
• /
• v.26 no.1
• /
• pp.1-7
• /
• 2010

Species diversity is one of the most important specifications of biological societies. Diversity of organisms, measurement of variety and examination of those hypotheses that are about reasons of diversity are such as affairs that have been desired by the ecologists for a long time. In this research, diversity of plant species in forest region, numbers of 60 sample plots in 256.00 square meters have been considered in random - systematic inventory was considered. In each sample plot, four micro-plots in 2.25 square meters in order to study on herbal cover, were executed that totally 240 micro-plots were considered. At each plot six diversity indices in relation to physiographic factors (slope, geographical aspect and altitude from the sea level) were studied. The results indicate that species diversity is more in the northern direction and also species diversity in slops less than 30% has the most amounts. Factor of altitude from the sea level did not have meaningful relation with species diversity. Through study on correlation of the numbers of species in sample plots with indices and also process and role of indices in different processors of analysis, Simpson's reciprocal index was suggested as suitable index in this type of studies.

• Journal of Forest and Environmental Science
• /
• v.27 no.1
• /
• pp.1-15
• /
• 2011

The present study was undertaken in middle altitudinal (1500 to 2500 masl) moist temperate forest of Mandal-Chopta area in the Garhwal region of Uttarakhand, India. The aim of the present study was to assess the variation in species composition and diversity in different vegetation layers viz. herb, shrub and tree, at different altitudes. Shannon-Wiener diversity index ($\bar{H}$), $Nha^{-1}$, total basal cover per hectare (G), Simpson concentration of dominance, Pielou Equitability, species richness (SR), Margalef index, Menheink index of species richness and ${\beta}$-diversity were calculated to understand community composition. Tree G ranged from 84.25 to 35.08 $m^2ha^{-1}$ and total stem density varied from 990 to 1470 Nha-1. Total SR (herb, shrub and trees) among different forest types ranged between 31 and 58. Maximum G of herb and shrub layers was recorded at lower altitudes between 1500 and 1650 masl. ${\beta}$-diversity was higher in herb layers as compared to tree and shrub layers. Dominance-diversity curves were also drawn to ascertain resource apportionment among various species in different forest types. Values of species diversity, $\bar{H}$, $Nha^{-1}$ and G were higher in the study area as compared to similar forests growing in other parts of Uttarakhand Himalaya.

• Journal of Global Scholars of Marketing Science
• /
• v.7
• /
• pp.71-103
• /
• 2001

Marketing practice varies among firms. However, the prescriptive literature emphasises a universal view of practice, a 'one size fits all' view. This paper addresses the issue of explaining diversity in marketing practice in competitive space and in time. Diversity in competitive space reflects the existence of different routes to high performance. Diversity in time reflects some combination of change in the individual firm and change in a population of firms. In the former case, diversity is shaped by organisational change; in the latter by the disbandment and founding of firms in the population. In so far as diversity is the norm, the manner in which practice will be shaped by evolutionary processes is considered. Fnally, the role of the academy as one of the forces driving the evolutionary process is discussed. Miles and Snow's (1978, 1986) work is taken as a main point of departure in the search for explanation and ecological and evolutionary concepts are drawn on for support and to suggest an explanation for the nature of diversity over time.

• Journal of Life Science
• /
• v.12 no.1
• /
• pp.27-32
• /
• 2002

Enzyme electrophoresis was used to estimate genetic diversity and population structure of maize, Zea mays L. (Graminales) in Korea. In nine populations, fourteen of the 24 loci (58.3 %) showed detectable polymorphism. Genetic diversity (0.205) was higher than average values for species with similar life history traits. Although our data are relatively small and the landraces not direct ancestors of cultivar, apparently the domestication process has eroded the levels of genetic variation of maize. The recent cultivars were found to have fewer alleles per locus (1.42 vs. 1.56), fewer alleles per polymorphic locus (2.27 vs. 2.33), lower percent polymorphic locus (33.3% vs. 41.7%), and lower diversity (0.159 vs. 0.185) than landraces. These genetic diversity parameters indicated that the cultivar populations were genetically depauperate relative to landlaces. The GST value of nine populations was 0.239. Nearly 76% of the total genetic diversity in Zea mays was apportioned within populations. The indirect estimate of gene new based on mean GST was moderate (Nm=0.80).

• Korean Journal of Poultry Science
• /
• v.43 no.2
• /
• pp.63-76
• /
• 2016

The genetic diversity of Korean native chicken is important for conservation of native chicken breeds and developing economically valuable traits in Korea. In this review, various types of genetic markers using Korean native chickens were investigated, which are mtDNA variations, microsatellite markers, markers in Major Histocompatibility Complex (MHC), and single nucleotide polymorphisms (SNPs). These genetic markers are suitable for breed discrimination and diversity studies because of their high polymorphism status. Thus, the purpose of this study was to summarize the genetic markers developed in the Korean native chickens and diversity studies using these breeds. Ultimately, these markers can be used for the future studies for understanding of genetic characteristics.

• Korean Journal of Breeding Science
• /
• v.41 no.4
• /
• pp.369-376
• /
• 2009

Cowpea might have been introduced from China to Korea and cultivated for several hundred years but it has never been a staple food crop in Korea. In this study, genetic diversity of 492 Korean cowpea landrace accessions that have passport information was estimated using six SSR markers. The mean of Weir's gene diversity was 0.665 from all accessions investigated in the study. Cowpea gene diversity of six local provinces in Korea was ranged from 0.370 in accessions of Gangwon to 0.680 in Jeonra provinces. Low gene diversity of the cowpea genepool of Gangwon province was probably derived from relatively few introductions. Especially SSR markers VM36 and VM39 seem to be good markers to distinguish the Gangwon accessions from others by occurring at a specific locus with higher than 78% of allele frequency. Except for the Gangwon province with the low genetic diversity, gene diversity of cowpea accessions from other provinces was ranged from 0.600 to 0.680 indicating no big differences among provinces. Distribution pattern of the allele frequencies was similar among the other provinces. This may reveal that Korean farmers might exchange cowpea seeds easily with even their neighbors with geographical barriers. A core collection, 100 landraces, ca. 20% of base collection, was developed at the 70% of a similarity coefficient level using random sampling approaches after stratification of the entire landrace collection based on the phenetic dendrogram. The variability of SSR in the base and core collections of Korean cowpea landrace was compared by calculating Weir's gene diversity. The mean of Weir's gene diversity of the core was 0.707 while that of the base collection was 0.665. The higher diversity index in the core collection indicates that it maintains the initial variability and well represents the base collection. The core collection included one of determinate accession (IT 216155) and two of no branching type accessions (IT 103959 and IT 161024). The core collection could be used to guide more efficient management and utilization of the entire collection. This core collection should be revised periodically as additional accessions are collected and further characterization is conducted.