• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.3
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• pp.1016-1033
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• 2016

In this paper, we present a joint relay-and-antenna selection and power allocation strategy for multiple-input multi-output (MIMO) amplify-and-forward (AF) two-way relay networks (TWRNs). In our approach, we select the best transmit and receive antennas at the two sources, a best relay and a best transmit and receive antenna at the selected relay based on maximizing the minimum of the end-to-end received signal-to-noise-ratios (SNRs) under a total transmit power constraints. We obtained the closed-form solution for the optimal power allocation firstly. Then with the optimal allocation solution we found, we can reduce the joint relay-and-antenna selection to a simpler problem. Besides, the overall outage probability is investigated and a tight closed-form approximation is derived, which provides a method to evaluate the outage performance easily and fast. Simulation results are presented to verify the analysis.

• The Korean Journal of Health Service Management
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• v.14 no.1
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• pp.43-53
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• 2020

Objectives: The purpose of this study was to investigate the factors of importance in the medical field from the perspective of the consumer, using "Consumption Life Indicators in Korea." Methods: We examined the general characteristics, economic conditions, information acquisition, complaint-provoking experiences, cognitive score on dispute resolution, and factors affecting medical domain importance selection, using SAS 9.4. software. Results: It was found that "age" among general characteristics and "income" among economic conditions were important factors in selecting medical domain importance. Thus, it was possible to reaffirm the poor health of socioeconomically vulnerable people and their socioeconomic difficulties. Conclusions: The medical domain selection group needs the attention of the government, medical institutions, academia, consumer groups, community service groups and professional organizations, and needs substantial economic support and customized education.

• Journal of the Korean Society of Food Culture
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• v.32 no.2
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• pp.111-117
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• 2017

The purpose of this study was to investigate the effects of emotional-utilitarian motivation on coffee shop selection attribution. Based on a total of 276 samples obtained from empirical research, the results of the survey were analyzed by using SPSS 22.0. The results of this study were as follows. Firstly, the results of exploratory factor analysis of coffee shop selection attribution emphasized service, coffee quality, diversity of menu, atmosphere, convenience, and price. Secondly, the customers showed higher emotional motivation than utilitarian motivation. Thirdly, emotional motivation had a significant effect on perception of 'service', 'coffee quality', and 'atmosphere'. On the other hand, utilitarian motivation had a significant effect on 'service', 'diversity of menu', 'convenience', and 'price'.

• Publications of The Korean Astronomical Society
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• v.27 no.5
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• pp.431-438
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• 2012

A number of middle and high school students are selected at the Korea Astronomy Olympiad (KAO) in every year. In the first stage of the selection, the resume, school transcript, and recommendation letters from teachers are referred. In the second stage, after video lectures and weekend observation classes, students are tested with on-line homeworks, and interviewed through internet. For 118 students who have gone through the second stage of the 2012 KAO, we have conducted a questionnaire survey, which asks the students the motivation and preparation for the KAO. The survey has also included inquiries for the selection process and education program of the 2012 KAO; the replies will be used as feedbacks for the next year's KAO. The survey has revealed that the first stage worked well, while the second stage needs to be improved in terms of fairness and objectivity. We have found that most students received private tutorings for the KAO, so we suggest efforts should be made for students to be able to prepare the KAO without receiving private tutorings.

• Journal of electromagnetic engineering and science
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• v.11 no.2
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• pp.133-142
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• 2011

Coded cooperation that integrates channel coding in cooperative transmission has gained a great deal of interest in wireless relay networks. The performance analysis of coded cooperation protocol with multiple relays is investigated in this paper. We show that the diversity order achieved by the coded cooperation in a multi-relay wireless network is not only dependent on the number of cooperating relays but is also dependent on the code-rate of the system. We derive the code-rate bound, which is required to achieve the full diversity gain of the order of cooperating nodes. The code-rate required to achieve full diversity is a linearly decreasing function of the number of available relays in the network. We show that the instantaneous channel state information (CSI)-based relay selection can effectively alleviate this code-rate bound. Analysis shows that the coded cooperation with instantaneous CSI-based relay selection can achieve the full diversity, for an arbitrary number of relays, with a fixed code-rate. Finally, we develop tight upper bounds for the bit error rate (BER) and frame error rate (FER) of the relay selection based on coded cooperation under a Rayleigh fading environment. The analytical upper bounds are verified with simulation results.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.2
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• pp.19-25
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• 2008

When there are numerous wireless communication systems co-existing in the limited available frequency resource, an unexpected time delay can be caused during the system switching. So, in order to reduce this time delay, a mode selection method is required. In this paper, we propose a mode selection method to minimize the time delay for multi-system wireless communication systems. For the sake of efficiency, the mode selection method is designed by analyzing the preamble characteristics of different standards. Instead of performing a full search, we propose the preamble partial search to reduce the time delay to a minimum. Simulated with Matlab in an additive white Gaussian noise(AWGN) environment with a signal to noise ratio(SNR) of 10dB and bit error rate(BER) of $10^{-6}$, we evaluated and showed the performance improvement gained by using our proposed mode selection method.

• Journal of the East Asian Society of Dietary Life
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• v.24 no.4
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• pp.488-502
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• 2014

Research on the actual state of healthy Korean food menu items made from environmentally-friendly organic foods showed that 65.6% of subjects had experience of purchasing environmentally-friendly organic foods, and both genders chose 'expensive but reliable' as their prime reason for purchasing. Having no experience of purchasing environmentally-friendly foods constituted 34.5% of respondents, and the reasons were 'high price' and 'finding no difference from ordinary food'. Research on awareness of healthy Korean food menu items made from environmentally-friendly organic ingredients showed that both men and women thought the given menu items were 'fresh' but had little awareness of other factors such as 'good value for price', 'good visual style' and 'various recipes'. Regarding development prospective of environmentally-friendly organic foods, the number of subjects who answered positively was 405 (93%), which indicates that most research subjects showed positive attitudes. Top-selling menu items in the grain section were Sundubu-jjigae, Dubu-kimchi and Jeonju-bibimbap, and pajeon took first place in the vegetable selection. Moreover, Imjasu-tang showed high scores in the meat section. Furthermore, research on menu selection showed that menu selection was usually dependent on 'the price of menu (3.86)', 'fresh ingredients (4.03)', 'harmony of color (3.65)' and 'mood of the day (3.25)'. Research on menu selection revealed that 'quality of food' factors had the greatest influence upon preference and purchase intention for environmentally-friendly organic foods. Visual and psychological factors and values had significant an effect. Therefore, the food service industry should use this study as a source to develop menu items, by considering quality and visual factors. In addition, there should be various research performed on marketing strategies about menus from using environmentally-friendly organic foods and high value products.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.459-468
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• 2015

In this paper, we consider an uplink multiuser hybrid beamforming system where an access point (AP) communicates with multiple users simultaneously. The performance of the uplink multiuser hybrid beamforming system depends on the effective channel which is given by the product of the channel matrix and the analog beams. Therefore, to maximize the performance, we need to obtain the channel information and then select the analog beams appropriately by using the acquired channel information. In this paper, we propose the channel estimation method and low complexity analog beam selection algorithm for the uplink multiuser hybrid beamforming system. Additionally, our analysis shows that the proposed low complexity analog beam selection algorithm provides much less complexity than the optimum analog beam selection algorithm. From the numerical results, we confirm that the proposed low complexity analog beam selection algorithm has little performance degradation in spite of much less complexity than the optimum analog beam selection algorithm under the equal system configuration.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.280-281
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• 2023

Wireless communication in marine environments requires a significant amount of power for long-range communication, resulting in high energy consumption. Moreover, the numerous constraints in marine environments make it difficult to apply existing wireless communication technologies, necessitating the development of new technologies to address these issues. This paper investigates beam selection technology for marine environments, which reduces overall power consumption and minimizes interference between signals by selecting and transmitting necessary beams for communication in a specific area, enabling better quality communication. We validate the energy efficiency of the beam selection technology through simulations and compare it with existing wireless communication technologies. The results show that beam selection technology consumes less power and provides better communication quality than existing wireless communication technologies. Therefore, beam selection technology plays a critical role in establishing efficient communication systems in marine environments, and its application can improve communication quality over a broader area.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.106-110
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• 2000

The researches classifying the artificial flaws in welding parts are performed using the pattern recognition technology. For this purpose the signal pattern recognition package including user defined function is developed and the total procedure is made up the digital signal processing, feature extraction, feature selection, classfier design. Specially it is composed with and discussed using the ststistical classfier such as the linear discriminant function classfier, the empirical Bayesian classfier.