• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.6
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• pp.3012-3028
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• 2017

In this paper, we propose a joint power control strategy for both the uplink and downlink transmission by considering the energy requirements of the user equipments' uplink data transmissions in data and energy integrated communication networks (DEINs). In DEINs, the base station (BS) adopts the power splitting (PS) aided simultaneous wireless information and power transfer (SWIPT) technique in the downlink (DL) transmissions, while the user equipments (UEs) carry out their own uplink (UL) transmissions by exploiting the energy harvested during the BS's DL transmissions. In our DEIN model, there are M UEs served by the BS in order to fulfil both of their DL and UL transmissions. The orthogonal frequency division multiple access (OFDMA) technique is adopted for supporting the simultaneous transmissions of multiple UEs. Furthermore, a transmission frame is divided into N time slots in the medium access control (MAC) layer. The mathematical model is established for maximizing the sum-throughput of the UEs' DL transmissions and for ensuring their fairness during a single transmission frame T, respectively. In order to achieve these goals, in each transmission frame T, we optimally allocate the BS's power for each subcarrier and the PS factor for each UE during a specific time slot. The original optimisation problems are transformed into convex forms, which can be perfectly solved by convex optimisation theories. Our numerical results compare the optimal results by conceiving the objective of maximising the sum-throughput and those by conceiving the objective of maximising the fair-throughput. Furthermore, our numerical results also reveal the inherent tradeoff between the DL and the UL transmissions.

• Nuclear Engineering and Technology
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• v.48 no.5
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• pp.1206-1218
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• 2016

This article proposes a highly reliable power and communication system that guarantees the protection of essential instruments in a nuclear power plant under a severe accident. Both power and communication lines are established with not only conventional wired channels, but also the proposed wireless channels for emergency reserve. An inductive power transfer system is selected due to its robust power transfer characteristics under high temperature, high pressure, and highly humid environments with a large amount of scattered debris after a severe accident. A thermal insulation box and a glass-fiber reinforced plastic box are proposed to protect the essential instruments, including vulnerable electronic circuits, from extremely high temperatures of up to $627^{\circ}C$ and pressure of up to 5 bar. The proposed wireless power and communication system is experimentally verified by an inductive power transfer system prototype having a dipole coil structure and prototype Zigbee modules over a 7-m distance, where both the thermal insulation box and the glass-fiber reinforced plastic box are fabricated and tested using a high-temperature chamber. Moreover, an experiment on the effects of a high radiation environment on various electronic devices is conducted based on the radiation test having a maximum accumulated dose of 27 Mrad.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.347-348
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• 2013

To obtain high conversion efficiency in InGaN-based solar cells, it is critical to grow high indium (In) composed InGaN layer for increasing sun light absorption wavelength rage. At present, most InGaN-based solar cells adopt InGaN/GaN multi-quantum-well (MQW) structure for high crystalline quality of InGaN with high In composition. In this study, we fabricated and compared the performances of two types of InGaN/GaN MQW solar cells which have the 15% (SC 15) and 25% (SC 25) of In composition at quantum well layer. Although both devices showed similar dark current density and leakage current, SC 15 showed better performance under AM 1.5G illumination as shown in Fig. 1. It is interesting to note that SC 25 showed severe current density decrease as increasing voltages. As a result, it lowered short circuit current density and fill factor of the device. However, SC 15 showed steady current density and over 75 % of fill factor. To investigate these differencesmore clearly, we analyzed their photoluminescence (PL) spectra under various applied voltages as shown in Fig. 2. At the same time, photocurrent, which was generated by PL excitation, was also measured as shown in Fig. 3. Further, we investigated the relationship between piezoelectric field and performance of InGaN based solar cell varying indium composition.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.1
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• pp.264-284
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• 2021

As the next-generation network architecture, software-defined networking (SDN) has great potential. But how to forward data packets safely is a big challenge today. In SDN, packets are transferred according to flow rules which are made and delivered by the controller. Once flow rules are modified, the packets might be redirected or dropped. According to related research, we believe that the key to forward data flows safely is keeping the consistency of flow rules. However, existing solutions place little emphasis on the safety of flow rules. After summarizing the shortcomings of the existing solutions, we propose FRChain to ensure the security of SDN data forwarding. FRChain is a novel scheme that uses blockchain to secure flow rules in SDN and to detect compromised nodes in the network when the proportion of malicious nodes is less than one-third. The scheme places the flow strategies into blockchain in form of transactions. Once an unmatched flow rule is detected, the system will issue the problem by initiating a vote and possible attacks will be deduced based on the results. To simulate the scheme, we utilize BigchainDB, which has good performance in data processing, to handle transactions. The experimental results show that the scheme is feasible, and the additional overhead for network performance and system performance is less than similar solutions. Overall, FRChain can detect suspicious behaviors and deduce malicious nodes to keep the consistency of flow rules in SDN.

• Journal of Korean Dental Hygiene Science
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• v.4 no.2
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• pp.43-52
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• 2021

Background: To explore the empathic abilities, communication competence, and attitudes toward the disabled, and to identify the relationship between these variables among female dental hygiene students. Methods: A self-administered questionnaire was used to collect data from 190 female students in their second and third year of study at the dental hygiene department of a university located in Gyeongsangnam-do province, South Korea, from September 2-11, 2020. Data were analyzed using descriptive analyses, t-test, analysis of variance, Pearson's correlation, and multiple regression using SPSS 20.0. Results: The participants' scores for empathic abilities, communication competence, and attitudes toward the disabled were 3.63, 3.69, and 3.54 points, respectively. A significant positive correlation was observed between empathic abilities and attitudes toward the disabled. Regarding the sub-elements of empathic abilities, the participants' attitudes toward the disabled had a significant positive correlation with the scales measuring their perspective-taking abilities and personal distress (p<.05). A positive correlation (p<.05) was observed between communication competence and attitudes toward the disabled. The students' attitudes toward the disabled were significantly influenced by the scale measuring their perspective-taking abilities (B=.210); those with a higher perspective-taking ability displayed more positive attitudes toward the disabled. Conclusion: Female dental hygiene students showed empathic abilities, which positively influenced their attitudes toward the disabled. Positive attitudes toward the disabled can contribute to improving the quality of medical services.

• Journal of Distribution Science
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• v.14 no.6
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• pp.89-98
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• 2016

Purpose - This article tackles risk communication issues and aims to address the characteristics of MERS risk information distribution in South Korea, and secondly to examine the communicative behavior of the public health authority in terms of the quality of communication strategies. Thirdly, the study attempts to figure out the risk communication to cope with MERS through the applications of SMCRE model in chronological order. We employ the social amplification of risk framework for analyzing the emergent public response as one of the main approaches. Research Design, Data and Methodology - The main framework of this study is theoretically based on the social amplification of risk, which describes signals about risk transmitted and processed by individuals and social groups. The model also reflects the interactions between social groups and institutes about disaster-related risk issues, which are potential amplifiers or attenuators of communication signals. S-M-C-R-E Model is methodologically employed to examine the social amplification for MERS risk information in each period, which we defined operationally. The proposed methodology allows the assessment of effectiveness and ineffectiveness on risk communication to be conceptualized as a countermeasure against disasters. The paper focuses on exploring how social risk amplification can be applied and organized in each stage. Results - The SMCRE model describes the exchange of risk information and is also applied to all forms of communication between stakeholders including public health authority, local government and media. Each factor of risk communication includes source, message, channel, receiver and effect. The results support that the effective risk communication involves not only the improved reliability of public health authority as a key factor of risk communication, but also a close cooperation and good collaboration with local governments. It does not seem to be possible that the government-initiated risk communication based on controllability and management cope effectively with infectious disease in early stage. The results of this study imply that the shared risks between local, regional and national authorities can enhance risk communication system. Conclusions - The study supports that the disparities in how disaster-related risk information is interpreted and coded, have made effective risk communication and public sense-making impeded. Our findings support a more communicative discussion about the role of risk information sharing between governments for the improvement of emergency management and underline the importance of social elements in the risk communication, such as relationship and trust building. Findings suggest that trust building between stakeholders could be added to help explain the processes of social amplification and attenuation of risk. It would be recommended that the continuous risk communication with all the involved stakeholders will be able to help national health promotion policy to be improved regarding emergency management. Furthermore, risk communication has to be a scientific approach for the communication pertaining to potentially sensitive or controversial situations with public concerns and low public trust.

• The Journal of Korean Academic Society of Nursing Education
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• v.19 no.3
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• pp.413-422
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• 2013

Purpose: This study was designed to explore the influencing factors on communication skill of nursing students and to investigate the relationship between learning style, critical thinking disposition and communication skill, Methods: The study sample was composed of 559 nursing students. Data was collected from 1st to 30th, May 2012 used a questionnaire which included Kolb's learning style inventory, critical thinking disposition inventory, communication skill inventory. The SPSS 18.0 Window program was used for descriptive statistics, t-test, ANOVA, Pearson's correlation coefficient, and stepwise multiple regression. Results: Learning styles of subjects were diverging 39.5%, accommodating 32.6%, assimilating 22.7%, and converging 5.2%. The total mean score of critical thinking disposition and communication skill was 3.58 and 3.39 respectively. The score of Critical thinking disposition(t=3.06, p=.002) and Communication skill(t=3.25, p=.002) significantly differed between clinical practice satisfaction. Communication skill was the most significant predictor and accounted for 41.3% of the variance in critical thinking disposition in nursing students. Conclusion: It is important for students to use all four learning styles rather than to rely on one style. There should be more emphasis placed on the development of positive critical thinking disposition and communication skill of nursing students.

• Korean Journal of Community Nutrition
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• v.15 no.2
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• pp.240-252
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• 2010

The purpose of this research was to develop risk communication (RC) strategy and educational web-site on food additives for elementary students and their parents to improve their perception on food additives and dietary life. First of all, a survey was conducted from 1,200 elementary children and their parents to diagnose the perception and information needs on food additives. The survey revealed that most children and their parents did not have enough knowledge on food additives and demanded the safety information on food additives. Second, previous researches on food communication were analyzed to develop a risk communication model, and it was directly applied in this study. Third, a web site (www.foodnara.go.kr/foodaddy) was developed to upload the education materials along with up-to-date information and classroom activities for teachers on food additives. Fourth, the developed homepage was evaluated by applying to about 100 children and parents each, and majority of them showed high levels of understanding (children 85.7%, parents 79%) and satisfaction (children 77.2%, parents 64%), and the effect of getting over the prejudice against food additives was observed. The RC model developed in this study could be applied to any food risk communication, and the content and materials in this web site including booklets, animations, and quiz could be used effectively to promote the communication on food additives. In the future, it will be necessary to advertise the web site to be utilized by various consumer levels and to update the contents continuously by developing consumer-friendly communication materials.

• Journal of Distribution Science
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• v.16 no.6
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• pp.85-96
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• 2018

Purpose - There are many antecedences and consequences of the positive emotions of customers. The purpose of this research is to examine how Chinese service companies improve not only the positive emotions of customers but also the quality of life through effective verbal and nonverbal communication. Furthermore, we tried to analyze the moderating role of negative expectancy disconfirmation perceived by customers in those causal relationships among the variables. Research design, data, and methodology - The eight hypotheses were proposed and we tested them empirically in this research. Four hypotheses were about the relationship among communication, positive emotion, trust and quality of life. The other four hypotheses were about the moderating effect of negative expectancy disconfirmation in the causal relationships among four variables such as communication, positive emotion, trust and quality of life. A total of 356 samples who had visited the service companies in China were surveyed and 8 hypotheses were tested by empirical analysis using SPSS and AMOS. Results - The results of this research are as follows. First, positive verbal communication and nonverbal communication of employees in the service company have a positive effects on the positive emotions of customers. Second, positive emotion has a positive effect on the overall quality of life on the customer side as well as the trust on the corporate side. Third, negative expectancy disconfirmation perceived by customers has negative moderating effect in the causal relationship between employees' positive verbal communication and customers' positive emotion, and it also has a negative moderating role in the causal relationship between customers' positive emotion and overall quality of life. Conclusions - Based on these results, there can be such implications as follows. First, managers and employees of service companies can induce positive emotion of customers through effective communication. Second, service companies should try to improve not only the corporate-side performance like trust but also the customer-side performance like quality of life. Third, it will be significant for them to lower the level of negative expectancy disconfirmation for the purpose of improving not only the positive emotions of customers but also the quality of customers' life.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1180-1187
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• 2020

A team of operators is required for nuclear power plant operation, and communication between the operators is an important aspect of the team's ability to successfully carry out tasks. It has been difficult to evaluate the quality of this communication though, and as the relationship between communication quality and team performance has yet to be clarified, it has not been applied to most human reliability analysis (HRA) methodologies. This study investigates the relationship between the quality of communication and team performance using data from a full-scope training simulator of a digital main control room (MCR). Two important characteristics of communication were considered to determine quality: each operator's ability to self-confirm the status of a given task in a digital MCR, and the type of communication, as divided into 1-way, 2-way, and 3-way between operators. To measure team performance, the concept of an unsafe act was employed, which is defined as a human error that has the potential to negatively affect plant safety. Analysis results showed that the communication quality and team performance were related to each other. With this more clearly defined relationship, the results of this study can be applied to related performance shaping factors to improve HRA.