• Industrial Engineering and Management Systems
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• v.15 no.4
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• pp.318-323
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• 2016

In the current study, factors affecting cheese brands products in grocery stores were evaluated with an emphasis on diversity. The sample data were collected from Noushad and Pegah Milk Industry in 2015 and data were extracted, reviewed, and analyzed from 435 grocery stores in Mashhad using seemingly unrelated regression model and particle swarm optimization algorithm. Results showed that optimum amount of Kalleh product diversity is higher than other competitors in the market, and Kalleh UF diversity is 100 to 250 grams, and Kalleh UF diversity with weight of 300 to 500 grams is more than other modes of diversity, and Kalleh brand must remove tin cheese from the market. Sabah Brand also should eliminate its glass and creamy diversity from market, UF diversity is mostly welcomed in market.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.3
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• pp.75-79
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• 1995

This paper derives the symbol error rate (SER) for quadrature amplitude modulation (QAM) with L-fold selection combining (SC) space diversity in Rayleigh fading channel. No analysis has been reported yet for theoretical SER performance of QAM with SC space diversity in Rayleigh fading channels. The formula is obtained by averaging the symbol error probability of M-ary QAM in an additive white Gaussian noise channel over the distribution of the maximum signal-to-noise ratio among all of the diversity channels. By giving the order of diversity, L, and the number of signal points, M, we have been able to obtain the SER performance of QAM with general SC space diversity. Analytical results show that the probability of error decreases with the order of diversity. We can also see that the incremental diversity gain per additional diversity decreases as the number of branches becomes larger.

• Journal of Information Science Theory and Practice
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• v.7 no.3
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• pp.31-39
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• 2019

Nowadays, recommender systems suggest lists of items to users considering not only accuracy but also diversity and novelty. However, suggesting the most diverse list of items to all users is not always acceptable, since different users prefer and/or tolerate different degree of diversity. Hence suggesting a personalized list with a diversity degree considering each user preference would improve the efficiency of recommender systems. The main contribution and novelty of this study is to tune the diversity degree of the recommendation list based on the users' variety-seeking feature, which ultimately leads to users' satisfaction. The proposed approach considers the similarity of users' desire diversity as a new parameter in addition to the usual similarity of users in the state-of-the-art collaborative filtering algorithm. Experimental results show that the proposed approach improves the personal diversity criterion comparing to the closest method in the literature, without decreasing accuracy.

• ETRI Journal
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• v.17 no.4
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• pp.25-35
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• 1996

This paper derives the symbol error probability for quadrature amplitude modulation(QAM) with L-fold space diversity in Rayleigh fading channels. Two combining techniques, maximal ratio combining(MRC) and selection combining(SC), are considered. The formula for MRC space diversity is obtained by averaging the symbol error probability of M-ary QAM in an additive white Gaussian noise(AWGN) channel over a chi-square distribution with 2L degrees of freedom. The obtained formula overcomes the limitations of the earlier work, which has been limited only to deriving the symbol error rate(SER) of QAM with two branch MRC space diversity. The formula for SC space diversity is obtained by averaging the symbol error probability of M-ary QAM in an AWGN channel over the distribution of the maximum signal-to noise ratio among all of the diversity channels for SC space diversity has been reported yet. Analytical results show that the probability of error decreases with the order of diversity gain per additional branch decreases as the number of branches becomes larger. On the other hand, the performance of 16 QAM with MRC becomes much better than that of SC as the number of branches becomes larger. By giving the order of diversity, L, and the number of signal points, M, we have been able to obtain the SER performance of QAM with general space diversity. These results can be used to determine the order of diversity to achieve the desired SER in land mobile communication system employing QAM modulation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.6
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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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6C
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• pp.423-428
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• 2008

We consider the use of cooperative diversity in a multiuser wireless data network. This paper provides an analysis of the interaction between cooperative diversity and multiuser diversity on downlink channels. By using approximation of the signal-to-noise ratio (SNR) distribution of each cooperative diversity link by Gamma distribution, an analytic expression is derived for the average throughput of a single-cell wireless system with multiple cooperative diversity links combined with a fair-access scheduler. The proposed analytic approach is verified through comparisons with simulated results and shows that cooperative diversity makes the detrimental impacts on multiuser diversity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2A
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• pp.183-190
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• 2008

The balanced Tx diversity with same data on two antennas can have better or lower performance than STBC Tx diversity, depending on the difference between each phase of two channels when the received signal is processed with MRRC. Therefore, using the feedback information based on the phase estimation in each channels, the better scheme of the balanced Tx diversity and STBC Tx diversity can be selected. However, when the phase condition changes during the transmission as the selected Tx. diversity scheme, the decoded bit can be erroneous because the previously estimated phase and newly estimated phase is different. In this case, the receiver should request the re-transmission of the just received signal to the transmitter part. Through computer simulation, it is shown that the combined scheme of the balanced Tx diversity and STBC Tx. diversity has better performance than STBC Tx diversity.

• Journal of the Korean Geographical Society
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• v.51 no.4
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• pp.559-576
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• 2016

The concept of 'cultural diversity' has emerged as a key concept and the buzzword of the 21st century's international community in education, science and culture sectors since UNESCO's "World Declaration on Cultural Diversity"(2001). However, the appropriate and correct implementation in educational level and in a subject scale can not be pursued without special understanding of multilateral implications of UNESCO's 'cultural diversity' because the concept of cultural diversity has been distributed to various applications according to individual scholars and institutions before the "World Declaration on Cultural Diversity" was released. The ultimate orientation of 'cultural diversity', the concept presented in "World Declaration on Cultural Diversity" is 'world peace' and 'the coexistence of various cultures of mankind'. In this regard, 'cultural diversity' has special 'educational' meaning to the next generation as well as the current one. Also, it is meaningful to take educational practices on cultural diversity in case of the "World Geography" subject in view of that international society of geographical education came up with "International Declaration of Geographical Education for Cultural Diversity" in the IGU(International Geographical Union) 2000. From this point of view, the author proposes that the 'cultural diversity' concept implies four folds of meanings as an ideology, as a symbol, as a vision, and as a epistemological turn based on the analysis of literatures on 'cultural diversity' of UNESCO, then presents an educational practice centering around the examples and its usage of teaching materials of cultural diversity.

• The Journal of Small Business Innovation
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• v.21 no.1
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• pp.43-59
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• 2018

This study investigates the relationship between venture capital (hereafter, VC) syndicate diversity and the IPO performance of an entrepreneurial company backed by the syndicate. Specifically, focusing on three types of diversity within a VC syndicate, which are aligned with Harrison and Klein's seminal categorization in 2007 (i.e., separation, variety, and disparity), this study suggests their distinct effects on performance. Two stage least square analyses with 1,127 VC syndicate investments made by 6,268 VC firms strongly supported the hypotheses. The results showed that that capacity diversity decreases the performance and that expertise diversity and network diversity increase it.

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