• Proceedings of the Korean Society of Computer Information Conference
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• 2016.07a
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• pp.321-322
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• 2016

본 논문에서는 장기간 게임을 접속하지 않던 이용자가 다시 게임에 복귀하는 요인이 무엇인지에 관한 조사 내용과 분석 결과를 제시한다. 어떤 요인이 이용자가 게임에 복귀를 결정하는 데에 있어 영향을 끼치는가를 바탕으로 새로운 게임을 기획하거나, 게임을 운영할 때 고려해야할 점을 제시한다. 이러한 조사와 분석이 온라인 게임 운영자 및 기획자의 실무에 많은 도움이 될 것으로 기대된다.

• KIISE Transactions on Computing Practices
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• v.23 no.11
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• pp.641-649
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• 2017

As Internet of Things devices become pervasive, services improve to better assess the context and to alert other users to deal with emergencies. Such services use Internet of Things devices to detect the context around the user and promptly notify public institutions, hospitals or other parental users in emergencies. Most of these systems analyze an event when the value of the device is unchanged for a period of time or if it detects an abnormal value. However, just monitoring sensor values makes it difficult to accurately understand the context surrounding a user. Also if the device is inactive, it can not identify the context or provide services again. However, understanding the user requirements, services provided through other devices, information sent to other users lets, appropriate actions be taken. This paper, proposes a device search method and system based on a context-aware model that includes user demands. The proposed system analyzes the user's context and demands by using data collected from the internet of things devices. If user devices are inactive, they can recognize other devices by searching for other devices and providing services to users again. Through the proposed method, the user-centric services are provided. This method also analyzes and responds to requirements in various emergencies.

• Journal of Advanced Navigation Technology
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• v.12 no.5
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• pp.429-436
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• 2008

In this paper, we study an optimization which determines the optimal sensing time and the number of cooperative sensing cognitive users for cooperative spectrum sensing scheme in cognitive radio networks. In cooperative spectrum sensing, cognitive users originally in inactive status are activated and take part in spectrum sensing along with transmitting cognitive users resulting in a reduced sensing time. Tradeoff between transmission rate gain and energy consumption due to cooperative sensing is formulated as a mixed integer programming problem which is solved for the optimal values.

• Journal of Industrial Technology
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• v.31 no.B
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• pp.99-105
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• 2011

Recently, smartphones have been widely used in wireless communications which caused severe data overload in cellular networks. Cellular companies consider increasing wireless data capacity in overloaded areas. Determining overloaded areas is mainly made from user reports which are currently collected by calling or simple apps by some active users experiencing overloads. Since the current reporting method is inconvenient and does not contain detail information about the overload conditions, and therefore is used by only some active users, the overloaded areas determined from the reports are not likely to be accurate. Therefore, we need a new reporting method which is convenient enough for even inactive users to willingly report the overload condition and which delivers detail information about the overloads. In this paper, we design and implement a measurement function of smartphone's WCDMA communication quality including overload condition and management system of mobile wireless communication networks about smartphones' communication quality.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.9
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• pp.2081-2100
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• 2013

In this paper, we propose a cooperative hybrid spectrum sharing protocol by jointly considering interweave (opportunistic) and underlay schemes. In the proposed protocol, secondary users can access the licensed spectrum along with the primary system. Our network scenario comprises a single primary transmitter-receiver (PTx-PRx) pair and a group of M secondary transmitter-receiver (STx-SRx) pairs within the transmission range of the primary system. Secondary transmitters are divided into two groups: active and inactive. A secondary transmitter that gets an opportunity to access the secondary spectrum is called "active". One of the idle or inactive secondary transmitters that achieves the primary request target rate $R_{PT}$ will be selected as a best decode-and-forward (DF) relay (Re) to forward the primary information when the data rate of the direct link between PTx and PRx falls below $R_{PT}$. We investigate the ergodic capacity and outage probability of the primary system with cooperative relaying and outage probability of the secondary system. Our theoretical and simulation results show that both the primary and secondary systems are able to achieve performance improvement in terms of outage probability. It is also shown that ergodic capacity and outage probability improve when the active secondary transmitter is located farther away from the PRx.

• The Journal of the Korea Contents Association
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• v.22 no.7
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• pp.46-54
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• 2022

The existing methods for determining influence in social networks do not accurately determine the influence of users because they do not delete or update existing relationships before they stop in the face of an increasing number of inactive users on social networks. In this paper, we propose a user influence detremination method using the temporal k-shell decomposition technique based on the creation date of users of social networks. To solve the problem of increasing influence of old users in social networks, we apply k-shell decomposition and age-specific order centrality as attenuation coefficients due to aging in neighbors. The age-decaying k-shell decomposition and age-specific order centrality are searched for influential users at the present time by applying the attenuation coefficient and age-dependent weights. Various performance evaluations are performed to show the superiority of the proposed method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.11
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• pp.5253-5270
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• 2016

With device-to-device (D2D) communications, an inactive user terminal can be utilized as a relay node to support multi-hop communication so that connective experience of the cell-edge user as well as the capacity of the whole system can be significantly improved. In this paper, we investigate the spectrum sharing for a cooperative relay assisted D2D communication underlying a cellular network. We formulate a joint relay selection and channel assignment problem to maximize the throughput of the system while guaranteeing the quality of service (QoS) requirements of cellular users (CUs) and D2D users (DUs). By exploiting coalition formation game theory, we propose two algorithms to solve the problem. The first algorithm is designed based on merge and split rules while the second one is developed based on single user's movement. Both of them are proved to be stable and convergent. Simulation results are presented to show the effectiveness of the proposed algorithms.

• Journal of Information Technology Services
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• v.15 no.2
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• pp.185-201
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• 2016

Recently, due to the rapid development of IT (information technologies), a variety of attempts have been made to incorporate IT into other fields such as finance and manufacturing. Among them, a novel concept in the spotlight is FinTech, which is a combined word of finance and technology. FinTech is a line of business demonstrating an innovation development through IT in the financial service industry. One of the most popular types of FinTech is a third-party mobile payment service (MPS), the examples of which can be easily found in South Korea while the actual use of the service is relatively inactive. Therefore, the main purpose of this paper is to empirically investigate influencing factors of intention to use the third-party MPS. Based on individual characteristics and the task-technology fit model, the research model of the study is developed, with switching cost included as a moderating variable. The results of structural equation model testing with 316 potential users of Kakao Pay, one of the most popular business models of the third-party MPS, show that innate innovativeness, task characteristics, and technology characteristics are positively influencing task-technology fit, which in turn significantly affects intention to use the third-party MPS. The negative moderating role of switching cost is also found. These results could help managers develop better strategies to motivate potential users to participate in their services.

• Genomics & Informatics
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• v.14 no.1
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• pp.34-40
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• 2016

Due to advances in omics technologies, numerous genome-wide studies on human samples have been published, and most of the omics data with the associated clinical information are available in public repositories, such as Gene Expression Omnibus and ArrayExpress. While analyzing several public datasets, we observed that errors in gender information occur quite often in public datasets. When we analyzed the gender description and the methylation patterns of gender-specific probes (glucose-6-phosphate dehydrogenase [G6PD], ephrin-B1 [EFNB1], and testis specific protein, Y-linked 2 [TSPY2]) in 5,611 samples produced using Infinium 450K HumanMethylation arrays, we found that 19 samples from 7 datasets were erroneously described. We also analyzed 1,819 samples produced using the Affymetrix U133Plus2 array using several gender-specific genes (X (inactive)-specific transcript [XIST], eukaryotic translation initiation factor 1A, Y-linked [EIF1AY], and DEAD [Asp-Glu-Ala-Asp] box polypeptide 3, Y-linked [DDDX3Y]) and found that 40 samples from 3 datasets were erroneously described. We suggest that the users of public datasets should not expect that the data are error-free and, whenever possible, that they should check the consistency of the data.

• Journal of Digital Convergence
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• v.13 no.5
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• pp.177-185
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• 2015

The gender difference in social roles affects digital devices' utilization differences in man and woman even in the 21st Century. Prior studies analyze the digital divide (genders, ages, etc.) from the assessment perspectives of digital equipment, such as PCs. In the area of high speed internet, most functions of PCs have been replaced with smartphones, and around 80% of the mobile phone users adopt smartphones. Subsequently the inequality of physical access to the digital devices is no longer a criterion for digital divide. The focus on digital divide should be shifted from the physical access to other factors, such as socio-technical or socio-cultural ones. This paper examines utilization of women's digital equipment, in particular, preparing for tourism activities, which is popular but sensitive to the technology. A survey was conducted with participants of [Suncheon Garden Expo] 2013. The results of this study capture the inactive use of digital devices particularly women over 50s. This phenomenon (high utilization of the digital devices for social or informative purposes, but low utilization of the digital payment) implies other aspects of Korean women (economic independence, low self-assertion, technical difficulties, etc.), which is considered from the socio-technological convergence perspective. This study also has a practical implication on the side of the digital device developers as well as marketing, where the qualitative communication is likely to be incorporated for the women over 50s.