• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5A
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• pp.325-338
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• 2012

In this paper, a radio resource allocation scheme for a multi-hop relay transmission in cognitive radio (CR) system is proposed to support the employment of relay nodes in IEEE 802.22 standard for wireless regional area network (WRAN). An optimization problem is formulated to maximize the number of serving secondary users (SUs) under system constraints such as time-divided frame structure for multiplexing and a single resource-unit to every relay-hop. However, due to mathematical complexity, the optimization problem is solved with a sub-optimal manner instead, which takes three steps in the order of user selection, relay/path selection, and frequency selection. In the numerical analysis, this proposed solution is evaluated in terms of service rate denoting as the ratio of the number of serving SUs to the number of service-requesting SUs. Simulation results show the condition of adopting multi-hop relay and the optimum number of relaying hops by comparing with the performance of 1-hop system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4748-4765
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• 2016

We consider a virtualized cognitive radio (CR) network, where multiple virtual network operators (VNOs) who own different virtual cognitive base stations (VCBSs) share the same physical CBS (PCBS) which is owned by an infrastructure provider (InP), sharing the spectrum with the primary user (PU). The uplink scenario is considered where the secondary users (SUs) transmit to the VCBSs. The PU is protected by constraining the interference power from the SUs. Such constraint is applied by the InP through pricing the interference. A Stackelberg game is formulated to jointly maximize the revenue of the InP and the individual utilities of the VNOs, and then the Stackelberg equilibrium is investigated. Specifically, the optimal interference price and channel allocation for the VNOs to maximize the revenue of the InP and the optimal power allocation for the SUs to maximize the individual utilities of the VNOs are derived. In addition, a low‐complexity ±‐optimal solution is also proposed for obtaining the interference price and channel allocation for the VNOs. Simulations are provided to verify the proposed strategies. It is shown that the proposed strategies are effective in resource allocation and the ±‐optimal strategy achieves practically the same performance as the optimal strategy can achieve. It is also shown that the InP will not benefit from a large interference power limit, and selecting VNOs with higher unit rate utility gain to share the resources of the InP is beneficial to both the InP and the VNOs.

• Knowledge Management Research
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• v.16 no.3
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• pp.41-63
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• 2015

This paper investigated main determinants of purchase intention for VOD contents by employing an extended technology acceptance model. The findings showed that 'user activeness' is the critical external variable influencing five perceived belief variables, namely perceived usefulness, perceived playfulness, perceived quality, perceived complexity and perceived cost. Regarding consumer satisfaction for free VOD service, it had no direct effect but indirect effect on the purchase behavior, meaning that the satisfaction causes purchase intention for VOD contents via the cognitive attitude. Also, the moderating e!ect of use experience on the relationship between the belief variables and the purchase intention was confirmed. Users with much experience showed a higher perception for usefulness and quality, whereas users with less experience placed a higher value on the hedonic factors and costs. In contrast to previous studies on IPTV that mainly focused on determinant of IPTV subscription, this paper analyzed VOD that is a killer application of IPTV in identification of key factors for the acceptance. The findings provide IPTV operators some strategies to create customer value and improve profitability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.10
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• pp.2609-2626
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• 2023

The hotel industry is an example of experiential services. As consumers cannot fully evaluate the online review content and quality of their services before booking, they must rely on several online reviews to reduce their perceived risks. However, individuals face information overload owing to the explosion of online reviews. Therefore, consumer cognitive fluency is an individual's subjective experience of the difficulty in processing information. Information complexity influences the receiver's attitude, behavior, and purchase decisions. Individuals who cannot process complex information rely on the peripheral route, whereas those who can process more information prefer the central route. This study further discusses the influence of the complexity of review information on hotel ratings using online attraction review data retrieved from TripAdvisor.com. This study conducts a two-level empirical analysis to explore the factors that affect review value. First, in the Peripheral Route model, we introduce a negative binomial regression model to examine the impact of intuitive and straightforward information on hotel ratings. In the Central Route model, we use a Tobit regression model with expert reviews as moderator variables to analyze the impact of complex information on hotel ratings. According to the analysis, five-star and budget hotels have different effects on hotel ratings. These findings have immediate implications for hotel managers in terms of better identifying potentially valuable reviews.

• Korean Journal of Cognitive Science
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• v.17 no.2
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• pp.119-138
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• 2006

It is widely known that chunking is beneficial to syntactic analysis. This paper introduces a method of chunking thai is useful for structural analysis of sentences in Korean. Dependent nouns in Korean usually tend to make sentences complex and long. By performing chunking operations related with dependent nouns, it is possible to reduce sentence complexity and thus make syntactic analysis easier. With this aim in mind we investigated techniques for chunking related with dependent nouns. We proposed a variety of chunking schemes according to the types of dependent nouns. The experiments showed that carrying out chunking leads to significant improvement of performance in syntactic analysis for Korean.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3789-3809
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• 2014

Radio environment maps (REMs) and geolocation database represent an important source of information for the operation of cognitive radio networks, replacing or complementing spectrum sensing information. This paper provides a survey of methods for constructing the radio frequency layer of radio environment map (RF-REM) using distributed measurements of the signal levels at a given frequency in space and time. The signal level measurements can be obtained from fixed or mobile devices capable of sensing radio environment and sending this information to the REM. The signal measurements are complemented with information already stored in different REM content layers. The combined information is applied for estimation of the RF-REM layer. The RF-REM construction methods are compared, and their advantages and disadvantages with respect to the spatial distribution of signal measurements and computational complexity is given. This survey also indicates possible directions of further research in indirect RF-REM construction methods. It emphasizes that accurate RF-REM construction methods should in the best case support operation with random and clustered signal measurements, their operation should not be affected by measurements outliers, and it must estimate signal levels comparably on all RF-REM locations with moderate computational effort.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.2
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• pp.75-82
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• 2012

In order to enable network robots to effectively collaborate with smart environments, it is crucial that various types of heterogeneous device platforms can communicate each other in flexible and efficient manners. Most of existing software platforms for network robots adopted general-purpose middlewares such as CORBA, which are not suitable to the communication between robots and smart environments due to their heavy size and complexity. Moreover, they do not provide network robot-specific features. Therefore, we propose a new TCP-based Remote Method Invocation framework. We devide the middleware into two layers i. e. transport layers and rmi layers and provide key features to each layer so that network robots can effectively communicate with various devices in smart environments.

• Journal of Communications and Networks
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• v.13 no.4
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• pp.360-366
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• 2011

In this paper, we investigate the problem of power allocation in a heterogeneous network that is composed of a pair of cognitive users (CUs) and an infrastructure-based primary network. Since CUs have only limited effective spectrum-sensing ability and primary users (PUs) are not active all the time in all locations and licensed bands, we set up a new multi-area model to characterize the heterogeneous network. A novel combined interference-avoidance policy corresponding to different PU-appearance situations is introduced to protect the primary network from unacceptable disturbance and to increase the spectrum secondary-reuse efficiency. We use dual decomposition to transform the original power allocation problem into a two-layer optimization problem. We propose a low-complexity joint power-optimizing method to maximize the transmission rate between CUs, taking into account both the individual power-transmission constraints and the combined interference power constraint of the PUs. Numerical results show that for various values of the system parameters, the proposed joint optimization method with combined PU protection is significantly better than the opportunistic spectrum access mode and other heuristic approaches.

• The Journal of Information Systems
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• v.24 no.1
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• pp.147-168
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• 2015

Why people reduce or stop using social network services(SNS), which are regarded as a mean of relationship and communication, unlike the early trend? To explain the phenomenon, this study tries to predict psychological decision making process of users from perspectives of cognitive dissonance theory. From this perspective, this study attempted an integrative approach that reflected 'User's literacy' indicating the ability of individuals to use SNS, and 'negative mass media influence' such as media reports on side effects or the bad experiences of acquaintances, along with the 3 factors used in the SNS Prior research. This study conducted an empirical analysis by surveying 256 facebook users, and the major findings are as follows:- First, Social-overload, complexity, uncertainty and negative media influence are significantly affect dissonance on the use of SNS. Second, Dissonance on the use of SNS significantly affects the behavior that possibly reduces and limits the use of SNS. In other words, the users who have experienced psychological dissonance respond passively by avoiding the use of SNS to resolve the dissonance. Third, the moderating effect of User's literacy wasn't a significant. This study presents a clue to understand psychological decision making process of use of SNS and a guideline for establishing practical strategies. In addition, it is important to note that this study contributes to expansion of theoretical discussion about usage.

• Journal of Information Science Theory and Practice
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• v.7 no.4
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• pp.6-19
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• 2019

The purpose of this article is to problematize the existence of a possible Ibero-American informational thinking. It was initially observed that a relative absence of Ibero-America in the international presentations and mappings of information science exists. Below, the reality of the 22 countries that compose Ibero-America is discussed, a region that can be understood from a sociocultural and geopolitical perspective. Then, a mapping of the information science research in these countries is made. The main research topics found are: epistemological studies, relationships with library science, information literacy, representation and organization, bibliometric studies, information management, user studies, technological dimensions, and relationships with archival science and museum studies. Finally, a general epistemological configuration of information science is presented at a global level, highlighting the great trends of study of information that marked the decades of the 1960s and 1970s (physical model), 1980s and 1990s (cognitive model), and the 21st century (sociocultural model), and which manifested themselves in the different subareas that make up the field. The most recent research in information science, in addition to addressing information transfer (physical dimension) and its relationship with data and knowledge (cognitive dimension), has also incorporated aspects related to the social effects of information, its role in the constitution of identities and culture, and the importance of its material conformations. Such expansion reflects attempts to address the complexity of informational phenomena. Therefore, it is concluded that it is important to place the specific contributions of Ibero-America in this context.