• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.4087-4102
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• 2014

Two-way relaying is an effective way of improving system spectral efficiency by making use of physical layer network coding. However, energy efficiency in OFDM-based bidirectional relaying with asymmetric traffic requirement has not been investigated. In this study, we focused on subcarrier transmission mode selection, bit loading, and power allocation in a multicarrier single amplified-and-forward relay system. In this scheme, each subcarrier can operate in two transmission modes: one-way relaying and two-way relaying. The problem is formulated as a mixed integer programming problem. We adopt a structural approximation optimization method that first decouples the original problem into two suboptimal problems with fixed subcarrier subsets and then finds the optimal subcarrier assignment subsets. Although the suboptimal problems are nonconvex, the results obtained for a single-tone system are used to transform them to convex problems. To find the optimal subcarrier assignment subsets, an iterative algorithm based on subcarrier ranking and matching is developed. Simulation results show that the proposed method can improve system performance compared with conventional methods. Some interesting insights are also obtained via simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10C
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• pp.946-954
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• 2009

General RFID system has assumed that the communication channel between reader and back-end database is secure channel. However, the reader can be communicated with the database through insecure channel like the communication channel between the reader and the tag according to application environment. In this paper, we propose a new secure RFID mutual authentication protocol based on open network channel which assumed that all communication channels between the database, the reader and the tag are insecure communication channels. The proposed protocol uses a secure one-way hash function to provide authentication and integrity against all communication messages which exchanged on the open channels. In addition, we designed that the proposed protocol can provide forward secrecy by performing the database and the tag update their old secret key with a new secret key after finished mutual authentication.

• Proceedings of the Korea Association of Information Systems Conference
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• 1997.10b
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• pp.271-285
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• 1997

This paper address the issues of satisfaction factors to measure the service quality in computer communication service users. In order to develope a satisfaction factors' model, we study appropriate quality factors of the service through the focus group interviews with service users, and surveys the quality levels that users have felt in services. It also analyzes the relationship between the user's quality level and the quality factors by the statistical analyses. Based on the optimal regression model, we suggest an appropriate satisfaction model in PC communication service areas. That model shows that most users are interested in the fare for use. Use-fare factor is the most powerful one to the satisfaction model. Second one is usefulness, next is correctness. But connect-status factor is the only negative one. Most users think that its factor is in the way of fluent communication. So to keep the competitiveness in the PC communication service, the sixth negative factor should be modified as soon as possible.

• Journal of the Korea Society of Computer and Information
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• v.16 no.2
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• pp.201-206
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• 2011

With the development and supply of digital displayers, there has been a heightened interest of late in digital photo frames, eclipsing the existing print frames. This digital photo frame was developed into a new LCD digital photo frame that can be used not only for data display but also as a surveillance monitoring equipment when combined with a CCD camera. The developed photo frame uses a one-way communication encryption method that replaces the existing two-way communication encryption method to ensure the security of the surveillance image data. This method uses the chaotic signal's one-way synchronization phenomenon, where synchronization is made for a certain amount of time, after which the synchronized data can be encrypted and decoded at any point. It can yield the same results as the two-way communication encryption method. Moreover, if the proposed method is applied to the close-range communication methods of ubiquitous devices, it will be able to obtain more efficient results.

• Journal of Digital Convergence
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• v.16 no.11
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• pp.433-440
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• 2018

The purpose of the study to investigate the effect of self-efficacy and communication ability to self-leadership of nursing students. The study conducted among 320 nursing students on May 2018 at one university. Data were analyzed by t-test, one-way ANOVA, pearson's correlation coefficient, stepwise multiple regression by using SPSS 18.0 program. The results of the study showed that there was a significant different according to the general characteristics in communication skills in the grade, self leadership in age and grade. However, Self-efficacy, communication skills and Self-leadership. showed a statistically positive correlation with self-leadership and communication skills (r = .376, p = .000) and self leadership and communication skills were 14.1% exhibited by nursing students. The study findings suggested that there is a need to develop multidimensional strategies to improve self-efficacy and self-leadership. Also, it is recommended that develop and implement various programs to understand the college life adaptation for nursing students.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3104-3110
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• 2011

This paper describes how to ensure safety of train by guaranteeing stable and continuous communication in RF-CBTC. CBTC System uses the wireless communication between onboard and wayside so that safety of wireless communication is the most important. Losing the position of train causes vital problem of train service. By losing the position of train, the other trains are blocked in the block and the train move by emergency mode so headway and safety cannot guaranteed. Therefore, safety is ensured by redundancy of wireless equipment. One of the ways to make redundancy is redundancy of equipment. However, the redundancy of equipment spends a lot of money to avoid interference in limited place like underground. Continuous communication is guaranteed by means of redundancy of wireless communication coverage to solve the problems even though one of the equipment is broken.

• Korean Journal of Child Studies
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• v.29 no.6
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• pp.35-54
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• 2008

This study analyzed feelings of happiness in 550 5th grade children (273 males and 277 females) in elementary schools in Seoul and other regions. Measurement tools included personality (Eysenk, 1975), communication types (Barnes & Olsen, 1982), cognitive happiness (Waterman, 1993 and Ryff, 1989), affective happiness (Campbell et al. (1976), and eight open-ended questions about happiness developed by the author. Data analysis was by $X^2$, one-way ANOVA, stepwise regression analysis, and two-way ANOVA. Happiness of children was influenced by school grades, existence of supporters, economic level, number of siblings, and gender. Extroverted female children who had open communication with parents felt the highest degree of happiness.

• Korean Journal of Childcare and Education
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• v.15 no.6
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• pp.207-226
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• 2019

Objective: The purpose of this study is to examine the relationship between caring thinking and communication skills of childcare center teachers, and the effect of caring thinking on communication skills. Methods: The subjects of this study were 152 teachers working at childcare centers in Gyeonggi-do, South Korea. The research tool used was a self-reporting questionnaire in order to examine caring thinking and the communication skills of those teachers. For the data analysis, one-way ANOVA, Pearson correlation analysis and multiple regression analysis were used. Results: First, there were significant differences in caring thinking and communication skills according to the age and academic background of the teachers. Second, there was a significant positive correlation between caring thinking and the communication skills of the teachers. Third, responsibility, respect, and a non-directive attitude among the sub-factors of the teachers had a significant impact on communication skills. Conclusion/Implications: In this study, it was found that caring thinking of the teachers was one of the variables that improved communication skills. These results suggest that there is a need to provide various programs and support for enhancing caring thinking as one of the ways to develop the communication skills of childcare center teachers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.12
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• pp.4967-4986
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• 2015

Multi-hop relaying communications have great potentials in improving transmission performance by deploying relay nodes. The benefit is critically dependent on the accuracy of the channel state information (CSI) of all the transmitting links. However, the CSI has to be estimated. In this paper, we investigate the channel estimation problem in one-way multi-hop MIMO amplify-and-forward (AF) relay system, where both the two-hop and three-hop communication link exist. Traditional point-to-point MIMO channel estimation methods will result in error propagation in estimating relay links, and separately tackling the channel estimation issue of each link will lose the gain as part of channel matrices involved in multiple communication links. In order to exploit all the available gains, we develop a novel channel estimation model by structuring different communication links using the PARAFAC and PARATUCK2 tensor analysis. Furthermore, a two-stage fitting algorithm is derived to estimate all the channel matrices involved in the communication process. In particular, essential uniqueness is further discussed. Simulation results demonstrate the advantage and effectiveness of the proposed channel estimator.

• Journal of Convergence for Information Technology
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• v.10 no.7
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• pp.75-83
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• 2020

This study aims to investigate the effects of nursing students' communication competence and nunchi on their interpersonal harmony. One-hundred and seventy-eight third- and fourth-year nursing students attending one of B, H, H, J, K universities in the North Jeolla Province were surveyed using a self-reported questionnaire. Independent t-test, one way ANOVA and Pearson's correlation coefficient, Stepwise regression were performed on the collected data using SPSS 21.0 program. Results The results showed that communication competence had the greatest impact on interpersonal harmony, followed by nunchi andsatisfaction with nursing major, with these variables explaining for 55% of interpersonal harmony. Hence, strategies that improve communication competence, nunchi, and satisfaction with nursing major would be helpful for increasing interpersonal harmony.