• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.12
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• pp.5898-5916
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• 2018

In this paper, the downlink performance of multi-cell distributed antenna systems (DAS) with a single user in each cell is investigated. Assuming the channel state information is available at the transmitter, four transmission modes are formulated as combinations of remote antenna units (RAUs) selection and cooperative transmission, namely, non-cooperative transmission without RAU selection (NCT), cooperative transmission without RAU selection (CT), non-cooperative transmission with RAU selection (NCT_RAUS), and cooperative transmission with RAU selection (CT_RAUS). By using probability theory, the cumulative distribution function (CDF) of a user's signal to interference plus noise ratio (SINR) and the system ergodic capacity under the above four modes are determined, and their closed-form expressions are obtained. Furthermore, the system energy efficiency (EE) is studied by introducing a realistic power consumption model of DAS. An expression for determining EE is formulated, and the closed-form tradeoff relationship between spectral efficiency (SE) and EE is derived as well. Simulation results demonstrate their consistency with the theoretical analysis and reveal the factors constraining system EE, which provide a scientific basis for future design and optimization of DAS.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.5
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• pp.1929-1943
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• 2021

Millimeter wave (mmWave) communication based on the wide bandwidth of >28 GHz is one of the key technologies for cellular-connected unmanned aerial vehicles (UAVs). The selection of mmWave beams in such cellular-connected UAVs is challenging and critical, especially when downlink transmissions toward aerial user equipment (UE) suffer from poor signal-to-interference-plus-noise ratio (SINR) more often than their terrestrial counterparts. This study proposed a coordinated mmWave beam selection scheme using fingerprint for cellular-connected UAV. The scheme comprises fingerprint database configuration and coordinated beam selection. In the fingerprint database configuration, the best beam index from the serving cell and interference beam indexes from neighboring cells are stored. In the coordinated beam selection, the best and interference beams are determined using the fingerprint database information instead of performing an exhaustive search, and the coordinated beam transmission improves the SINR for aerial UEs. System-level simulations assess the UAV effect based on the third-generation partnership project-new radio mmWave and UAV channel models. Simulation results show that the proposed scheme can reduce the overhead of exhaustive search and improve the SINR and spectral efficiency.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.3
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• pp.40-47
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• 2012

In dual-hop relaying systems, the conventional partial relay selection is based on the channel information only for the first hop. On the other hand, the efficient partial relay selection is based on the channel information for the hop with the minimum of the average channel powers for the first and second hops at each end-to-end link since the correlation coefficient between the end-to-end link quality and the link quality of the hop with the minimum of the average channel powers for the first and second hops is larger than that between the end-to-end link quality and the link quality of the other hop. In this paper, the outage probability of the conventional partial relay selection and the efficient partial relay selection in dual-hop decode-and-forward relaying systems is analyzed for non-identically distributed Rayleigh fading channels. Through numerical investigation, the outage performance of the efficient partial relay selection is compared with the outage performances of the conventional partial relay selection and the best relay selection based on all the channel information for the first and second hops.

• Journal of the Korean Society for Library and Information Science
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• v.39 no.2
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• pp.123-146
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• 2005

This study aims to find consistent strategies for feature selection and feature weighting methods, which can improve the effectiveness and efficiency of kNN text classifier. Feature selection criteria and feature weighting methods are as important factor as classification algorithms to achieve good performance of text categorization systems. Most of the former studies chose conflicting strategies for feature selection criteria and weighting methods. In this study, the performance of several feature selection criteria are measured considering the storage space for inverted index records and the classification time. The classification experiments in this study are conducted to examine the performance of IDF as feature selection criteria and the performance of conventional feature selection criteria, e.g. mutual information, as feature weighting methods. The results of these experiments suggest that using those measures which prefer low-frequency features as feature selection criterion and also as feature weighting method. we can increase the classification speed up to three or five times without loosing classification accuracy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8A
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• pp.581-590
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• 2003

This paper proposes the routing path selection mechanism for source routing-based PtMP (Point-to-Multipoint) call in ATM switching system. Especially, it suggests PtMP routing path selection method that can share the maximum resource prior to the optimal path selection, guarantee the reduction of path calculation time and cycle prevention. The searching for the nearest branch point from destination node to make the maximum share of resource is the purpose of this algorithm. Therefore among neighbor nodes from destination node by back-tracking, this algorithm fixes the node crossing first the node on existing path having the same Call ID as branch node, constructs the optimal PtMP routing path. The optimal node to be selected by back-tracking is selected by the use of Dijkstra algorithm. That is to say, PtMP routing path selection performs the step of cross node selection among neighboring nodes by back-tracking and the step of optimal node selection(optimal path calculation) among neighboring nodes by back-tracking. This technique reduces the process of search of routing information table for path selection and path calculation, also solves the cycle prevention easily during path establishment.

• Journal of the Korean Society of Costume
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• v.61 no.7
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• pp.51-66
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• 2011

The study is intended to suggest the differentiated and subdivided indexes of the leisure fashion market and to provide the marketing strategy establishment and in-depth understanding of leisure fashion business by looking into the correlation between and among fashion involvement, clothing selection criteria and fashion information sources. This study was conducted by the questionnaire response method and the results were derived by using the SPSS 16.0 statistics program. The results of the study were as follows; 1) As a result of researching the difference between the leisure activities consumer groups and fashion involvement, there were significant differences in emotional and cognitive involvement. In the tour activity group and social activity group, emotional involvement was found to be higher than the cognitive experience while in the hobby and sports activity group, both involvements were equally as high. 2) As a result of researching the difference between the leisure activities groups and clothing selection criteria, it was found that the intrinsic and extrinsic criteria were high in the hobby and sports activity group and that the intrinsic criteria was high in the tour activity group and social activity group. 3) In the difference between the leisure activity groups and fashion information sources, it was found that media source, observation source and experience/personal source were high in the hobby and sports activity group. In addition, the experience and personal source were high in the social activity group. 4) In the difference between and among fashion involvement, clothing selection criteria and fashion information sources, it was found that the emotional involvement, intrinsic criteria and observation source were higher in the group of females than males. 5) In the difference between and among fashion involvement, clothing selection criteria and fashion information sources depending on the ages of leisure activities consumers, it was found that the emotional involvement and observation source were high in the group of 20-24 yrs old consumers and that the emotional involvement, intrinsic criteria and observation source were high in the group of 25-29 yrs old consumers. Also, in the group of 30-34 yrs old consumers, the emotional involvement, observation source and experience/personal source were high.

• Journal of Korea Entertainment Industry Association
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• v.13 no.7
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• pp.61-74
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• 2019

The purpose of this study is to examine women's propensity to consume cosmetics and to investigate the effects of the consumption propensity on product selection attributes and information search behaviors. The purpose of this study is to propose practical implications for corporate management and to provide useful information for setting the marketing direction in the cosmetics industry by identifying differentiated marketing strategy for the cosmetics market. The results of the study are as follows. When the factors of each variable are extracted, the shopping propensity was derived from trend pursuit, pleasure pursuit, show-off pursuit, and economic benefit pursuit propensities, while product selection attributes were derived from brand factor, service factor, marketing factor, and quality factor. To examine the relationship between variables, three hypotheses were set based on previous studies. As a result of the verification the followings were found; first, the consumption propensity has a partial effect on the product selection attributes. Second, consumption propensity has a partial effect on information search behavior. Product selection attributes were found to have a partial effect on information search behavior.

• Journal of the Korea Society of Computer and Information
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• v.19 no.9
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• pp.197-204
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• 2014

RIP, EIGRP, OSPF are the interior gateway protocol for sending and receiving routing information among routers in AS(Autonomous System). Various path selection methods using the metric in regard to them have been studied recently but there are few examples that the contents learners understand theoretically are verified by the practice. The Best Path is determined by calculating the Cost value based on the relevant topology of each routing protocol. After implementing the virtual network, it is certain that the results tracking and verifying the relevant path selection of each routing protocol are consistent with the Best Path. If methods suggested in this paper are applied properly, the relevant path selection process of routing protocol can be understood systematically. And it is expected that the outstanding results of learning will be able to be achieved.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.51-53
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• 2015

In this paper, we propose a new relay selection technique which utilizes interference cancellation with decoding information at multiple relays for buffer-aided successive relaying systems. The transmitting relay is selected if its own transmission to the destination is successful and the number of relays which can successfully decode the data from the source is the maximum at the same time. Simulation results show that the proposed relay selection technique significantly outperforms the conventional relay selection scheme in terms of outage probability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.8
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• pp.1955-1971
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• 2013

This paper studies relay selection and power allocation for amplify-and-forward (AF) based two-way relay networks (TWRN) with asymmetric traffic requirements (ATR). A joint relay selection and power allocation algorithm is proposed to decrease the outage probability of TWRN with ATR. In this algorithm, two sources exchange information with the help of the relay during two time slots. We first calculate the optimal power allocation parameters based on instantaneous channel state information (CSI), and then derive a tight lower bound of outage probability. Furthermore, we propose a simplified relay selection criterion, which can be easily calculated as harmonic mean of instantaneous channel gains, according to the outage probability expressions. Simulation results verified the theoretical analyses we presented. It is shown that the outage probability of our algorithm improves 3-4dB comparing with that of other existing algorithms, and the lower bound is tight comparing with actual value for the entire signal-to-noise ratio (SNR) region.