• Proceedings of the ESK Conference
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• 2004.10a
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• pp.57-57
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• 2004

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.8
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• pp.3498-3511
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• 2016

We investigate the channel state information (CSI) in multi-input multi-output (MIMO) cooperative networks that employ the amplify-and-forward transmission scheme. Least squares and expectation conditional maximization have been proposed in the system. However, neither of these two approaches takes advantage of channel sparsity, and they cause estimation performance loss. Unlike linear channel estimation methods, several compressed channel estimation methods are proposed in this study to exploit the sparsity of the MIMO cooperative channels based on the theory of compressed sensing. First, the channel estimation problem is formulated as a compressed sensing problem by using sparse decomposition theory. Second, the lower bound is derived for the estimation, and the MIMO relay channel is reconstructed via compressive sampling matching pursuit algorithms. Finally, based on this model, we propose a novel algorithm so called sparsity adaptive expectation maximization (SAEM) by using Kalman filter and expectation maximization algorithm so that it can exploit channel sparsity alternatively and also track the true support set of time-varying channel. Kalman filter is used to provide soft information of transmitted signals to the EM-based algorithm. Various numerical simulation results indicate that the proposed sparse channel estimation technique outperforms the previous estimation schemes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.2
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• pp.726-741
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• 2022

The purpose of this study is to provide instructive theoretical models for art (music) education institutions especially when unpredictable risks, such as pandemics, occur again. Based on the customer behavior theory of the business-to-business-to-customer (B2B2C) platform, and in combination with the technology acceptance model (TAM) and expectation confirmation model (ECM), this study proposes an online education model from the perspective of art education. The framework is based on the three decision-making processes of the customer, and includes the product owner, content owner, and customer area. This paper highlights the factors that influence customers in making decisions when art education institutions are product owners. Regression analysis was introduced to study the factors influencing the expectation confirmation, and the overall fitting testing and six hypotheses testing of 385 effective samples were performed using the structural equation modeling (SEM). The results show that the course-design and after-service positively influenced the expectation confirmation, and the domain image positively influenced the continuance behavior. Negative emotions skipped the mediator (expectation confirmation) and directly exerted a significant negative impact on customers' willingness to continue system usage (continuance behavior). In addition, expectation confirmation positively influenced continuance behavior. The paths of detailed items comprising course-design, after-service, and negative emotion were also analyzed and discussed. In this path analysis, ordinary art learners did not believe that AI partners can play a very good auxiliary role. The findings contribute to the scope of information systems acting as an art education platform academically, and provide effective and theoretical support for the actual operation of art education institutions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.6
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• pp.2446-2462
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• 2016

In this paper, a frequency domain Expectation-Maximization (EM)-based channel estimation algorithm for Space Time Block Coded-Orthogonal Frequency Division Multiplexing (STBC-OFDM) systems is investigated to support higher data rate applications in wireless communications. The computational complexity of the frequency domain EM-based channel estimation is increased when higher order constellations are used because of the ascending size of the search set space. Thus, a search set reduction algorithm is proposed to decrease the complexity without sacrificing the system performance. The performance results of the proposed algorithm is obtained in terms of Bit Error Rate (BER) and Mean Square Error (MSE) for 16QAM and 64QAM modulation schemes.

• Journal of Korean Academy of Nursing
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• v.33 no.8
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• pp.1135-1144
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• 2003

Purpose. This study was conducted to understand the degree of internet addiction tendency and to find out the factors influencing this addiction tendency among middle school students in Gyeong-buk area. Methods. A total of 450 middle school students in the Daegu and Gyeong-buk area were surveyed in this study. Data collection was conducted through the use of questionnaires. Results. Internet addiction among middle school students was relatively low (Average user). In the overall ratio distribution, however, students who were classified as either addicted or at risk of addiction accounted for a high percentage, 27%. A positive correlation was found between Internet addiction and Internet expectation, depression and parent control over Internet use. A negative correlation was found between Internet addiction and interpersonal relationship, parent support and self-control. Multiple regression analysis revealed that the most powerful predictor of Internet addiction tendency was depression. Conclusion. Through the above results, it would be necessary to develop an Internet addiction prevention program for adolescents taking into account for the psychological factors such as depression and Internet use habits. In the future study, the need assessment will be useful for developing this prevention program.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.3
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• pp.175-184
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• 2023

Korean Wave is now internationalized through the internet by social media, which have no space-time restrictions. This research examine the continuance use of K-Pop promotion using social media in Indonesia. In this study we apply the Expectation-Confirmation Model to analyze the effects of individual self-efficacy and perceived enjoyment on perceived usefulness, confirmation, and satisfaction of Social Media. As a research method for that purpose, the conformity of the model and the research hypothesis were verified using the structural equation model. As a result, it was found that the perceived enjoyment positively influences perceived usefulness, self-efficacy has a positive influence on perceived usefulness. We also found that confirmation positively affects both perceived usefulness and satisfaction, and that perceived usefulness positively affects satisfaction. Finally, satisfaction was found to always have a positive effect on intention to use.

• International journal of advanced smart convergence
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• v.9 no.3
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• pp.215-220
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• 2020

The purpose of this study is to analyze the structural relationship among expectation value(relational, hedonistic), brand image, brand attitude, continuance viewing intention. The survey subjects to achieve the purpose of this study were selected the 521 YouTube sports contents Viewer in the metropolitan area. Data processing was done with SPSS 23 for frequency analysis, Cronbach's α analysis. Also, AMOS 21 was used for confirmatory factor analysis and structural equation model analysis. The results of the analysis are as follows: First, both relational value and,, hedonistic value had a positive effect on the brand image. Second, both relational value and,, hedonistic value had a positive effect on the brand attitude. Third, both brand image and brand attitudee had a positive effect on the brand attitude.

• Journal of Digital Convergence
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• v.7 no.4
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• pp.31-42
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• 2009

As a development of IT, the most part of societies apply it. Political area is not an exception. Most of candidates, parties and government make web sites to provide political information. But the political information of internet don't have a positive influence to electors always. On the assumption that the people who seek political information from internet are concerned at politics, the fact that the users don't affect at the internet political information demands close investigation. In this study I suggest that the reason is the difference forms of the political information provided from politician with netizen's expectation at the Internet.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.397-398
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• 2007

Currently, most of Passenger Service System is supported to VOD in Korea. This current PSS has not internet access, real time broadcasting system and entertainment. The system did not come up to the expectation of consumer. This paper presents an application of new Passenger Service System for developing multimedia as well as wireless communication technology on internet, satellite broadcasting.

• Journal of Digital Convergence
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• v.16 no.12
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• pp.267-281
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• 2018

Internet only Banks in Korea have acquired more than seven million customer base, but most of the accounts are not active. As financial products tend to be similar, customer affect plays more crucial role than service features in continuance intention. The purpose of this research is to study about the impact of positive and negative affect on the continuance intention. The result indicated that positive affect is positively related to continuance intention, and negative affect is negatively related to continuance intention. Also expectation confirmation is positively related to positive affect. The results imply Internet only Banks need to focus on customer's positive affect and expectation confirmation to improve continuance intention.