• Journal of information and communication convergence engineering
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• v.9 no.4
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• pp.391-395
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• 2011

Cognitive radio (CR) technique is a useful tool for improving spectrum utilization by detecting and using the vacant frequency bands while avoiding interference to the primary user. The sensing performance in a CR network can be improved by allowing some CR users to perform cooperative spectrum sensing. In this paper, we propose a new sensing algorithm that utilizes an adaptive energy threshold for cooperative spectrum sensing in which a changeable energy threshold is adopted by the CR users for improving local sensing performance. Through the proposed scheme, the reliability of global decision can be enhanced mainly due to the improvement in local sensing performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.728-729
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• 2010

Opportunistic spectrum access (OSA) allows unlicensed users to share licensed spectrum in space and time with no or little interference to primary users, with bring new research challenges in MAC design. We propose a cognitive MAC protocol using statistical channel utilization information and selecting appropriate spectrum hole for multi-channel data transmission. The protocol based on the CSMA/CA, exploits statistics of spectrum usage for decision making on channel access.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.4034-4053
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• 2015

In order to meet various requirements for transmission quality of both primary users (PUs) and secondary users (SUs) in cognitive radio networks, we introduce a channel bonding mechanism for PUs and a channel reservation mechanism for SUs, then we propose a novel spectrum allocation strategy. Taking into account the mistake detection and false alarm due to imperfect channel sensing, we establish a three-dimensional Markov chain to model the stochastic process of the proposed strategy. Using the method of matrix geometric solution, we derive the performance measures in terms of interference rate of PU packets, average delay and throughput of SU packets. Moreover, we investigate the influence of the number of the reserved (resp. licensed) channels on the system performance with numerical experiments. Finally, to optimize the proposed strategy socially, we provide a charging policy for SU packets.

• Annual Conference of KIPS
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• 2019.05a
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• pp.86-88
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• 2019

In a complex geographical environment, communication quality of communication equipment is being seriously challenged. Secondary Users(SUs) must make the best possible use the idle spectrums that Primary Users(PUs) do not use and change spectrum frequently. Using the relevance vector machine(RVM) to establish a signal noise Ratio(SNR) Model for interference information and bit error rate(BER). Through the model and real-time interference information, the minimum channel SNR meeting the BER requirements of communication equipment can be predicted, and we can also calculate the minimum transmitted power. According to the simulation results, this method has better performance for selecting available channel and restraining interference.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.12
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• pp.5841-5859
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• 2018

The widespread adoption of the social computing paradigm has ushered in the development of online social innovation community (OSIC) as a promising method for solving social problems. Previous studies have not explicitly considered the conceptual factors that facilitate these communities' users' innovative activities, so it is vital to conduct empirical studies to verify the effectiveness of these factors. In this paper, the primary goals are to construct a theoretical model of the social innovation and empirically verify the casual relationship between theoretical factors and societal innovativeness. A survey of 398 OSIC users was conducted to empirically validate the theoretical model. The causal relationships between network characteristics and social innovativeness were experimentally tested. The results of this study indicated that ambiguity, switching, and multiplexity are important factors that facilitate social innovativeness, which contradicts the prior assumptions about innovation performance.

• International journal of advanced smart convergence
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• v.10 no.2
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• pp.10-14
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• 2021

Today people adopt various contents from their mobile devices which lead to numerous platforms. As technology of 5G, IOT, and smart phone develops, the number of people who create, edit, collect, and share their own videos, photos, and articles continues to increase. As more contents are shared online, the numbers of data being stolen continue to increase too. To prevent these cases, an authentication method is needed to encrypt the content and prove it as its own content. In the report, we propose a few methods to secure various misused content with secondary security. A unique private key is designed when people create new contents through sending photos or videos to platforms. The primary security is to encrypt the "Private Key" with a public key algorithm, making its data-specific "Timeset" that doesn't allow third-party users to enter. For the secondary security, we propose to use Message Authentication Codes(MACs) to certify that we have produced the content.

• Journal of Audiology & Otology
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• v.23 no.3
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• pp.135-139
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• 2019

Background and Objectives: This study was undertaken to investigate the educational status in bilateral prelingual deaf children with a cochlear implant (CI), also known as early cochlear implantees (CIs). Type of schooling and enrollment rate of tertiary education were analyzed as primary results. Subjects and Methods: Participants in this study comprised a highly homogeneous group of deaf patients who underwent cochlear implantation at a similar age. Sixty-four Korean patients were enrolled. Statistical data for disabled populations and the general population were obtained from the National Statistics Korea. Results: Among 64 patients, 46, 8, and 10 attended mainstream, integrated, and special schools, respectively. Notably, there was a significant difference in the type of school between hearing-impaired and CI groups (p=0.007). Ten of 13 patients enrolled in tertiary education. Conclusions: CI users were more likely than hearing impaired students to attend mainstream school. The enrollment rate of CI users in tertiary education was the same as that of the general population.

• Korean Journal of Audiology
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• v.23 no.3
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• pp.135-139
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• 2019

Background and Objectives: This study was undertaken to investigate the educational status in bilateral prelingual deaf children with a cochlear implant (CI), also known as early cochlear implantees (CIs). Type of schooling and enrollment rate of tertiary education were analyzed as primary results. Subjects and Methods: Participants in this study comprised a highly homogeneous group of deaf patients who underwent cochlear implantation at a similar age. Sixty-four Korean patients were enrolled. Statistical data for disabled populations and the general population were obtained from the National Statistics Korea. Results: Among 64 patients, 46, 8, and 10 attended mainstream, integrated, and special schools, respectively. Notably, there was a significant difference in the type of school between hearing-impaired and CI groups (p=0.007). Ten of 13 patients enrolled in tertiary education. Conclusions: CI users were more likely than hearing impaired students to attend mainstream school. The enrollment rate of CI users in tertiary education was the same as that of the general population.

• International Journal of Internet, Broadcasting and Communication
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• v.16 no.2
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• pp.31-42
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• 2024

Today, news avoidance has become an inevitable trend, particularly exacerbated since the outbreak of the COVID-19 pandemic in 2020. To delve deeper into the shifting tendencies of news consumers towards news avoidance and unveil the motivations behind this avoidance, this study recruited 500 Chinese news consumers aged between 20 and 60 years old, employing survey questionnaires as the research method. Through an indepth examination of their news consumption behavior at different stages of the COVID-19 pandemic, we discovered that individuals' risk perceptions and efficacy beliefs significantly influence their patterns of news consumption. Furthermore, we identified negative emotions, information overload, and media distrust as the primary reasons for news avoidance among Chinese news consumers during the COVID-19 crisis. These findings Not only provide crucial insights into understanding the dynamics of news consumption behavior but also offer valuable reference points for the news industry to better fulfill its role and value during crises in the future.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.5
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• pp.285-297
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• 2014

This paper presents the results of an investigation into bi-directional communication in spectrum sharing-based cognitive radio (Bi-CR) systems. A Bi-CR system can increase the spectral efficiency significantly by sharing the spectrum and through the bi-directional use of spatial resources for two-way communication. On the other hand, the primary user experiences more interference from the secondary users in a Bi-CR system. Satisfying the interference constraint by simply reducing the transmission power results in performance degradation for secondary users. In addition, secondary users also experience self-interference from echo channels due to full duplexing. These imperfections may weaken the potential benefits of the Bi-CR system. Therefore, a new way to overcome these defects in the Bi-CR system is needed. To address this need, this paper proposes some novel power allocation schemes for the Bi-CR system. This contribution is based on two major analytic environments, i.e., noise-limited and interference-limited environments, for providing useful analysis. This paper first proposes an optimal power allocation (OPA) scheme in a noise-limited environment and then analyzes the achievable sum rates. This OPA scheme has an effect in the noise-limited environment. In addition, a power allocation scheme for the Bi-CR system in an interference-limited environment was also investigated. The numerical results showed that the proposed schemes can achieve the full duplexing gain available from the bi-directional use of spatial resources.