• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.7A
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• pp.560-568
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• 2012

Spectrum sensing and spectrum decision are the main functions that cognitive radios (CRs) have to perform in order to get the best available spectrum band for the establishment of a wireless communication. These problems are worsened in the presence of users with different demands and spectrum channels with different properties in a heterogeneous network. The primary objective in this work is to design and simulate a new spectrum decision algorithm for heterogeneous cognitive radio system. To this end, first, we consider all cognitive users are separated into different traffic classes according to their Quality of Service (QoS). The cognitive users within one traffic class perform spectrum sensing in centralized group-based cooperative spectrum sensing system and the users of different traffic classes share the sensing results. Second, we propose a novel use of the Analytic Hierarchy Process (AHP) to optimally select available bands according to user requirements and detected spectrum channel characteristics (SCC). In this paper, utility function is used as spectrum decision algorithm. Simulation results demonstrate that the proposed method shows can effectively select the best available spectrum channels with a low complexity.

• Archives of design research
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• v.19 no.2 s.64
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• pp.251-260
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• 2006

Rapid development of electronic technology has made it possible to perform various function. But this technology made it increase it's complexity. Therefore, It was important to identify usability problem in interface design. The quality of interface to promote the efficient interaction should be evaluated with regard to users' cognitive characteristics. So, in this paper, washing machine, that is one of the most useful electronic home application was studied menu structure on interface and it's operational states transition. At first, an cognitive menu structure is identified with users' conceptual similarity of the main function of washing machine. Then three washing machines was selected to compare with the cognitive menu structure. And, we were analyzed how operational state of the washing machine was transfered. As a result, we can be revealed that menu operational method based on the cognitive structure was consistent with the user's preferred operational method during the experimental tasks and the users and designers had a different knowledge of an it's function structure. These results will be useful to design the washing machine interface.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.9
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• pp.3172-3193
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• 2022

Cognitive radio-simultaneous wireless information and power transfer (CR-SWIPT) has attracted much interest since it can improve both the spectrum and energy efficiency of wireless networks. This paper focuses on the resource sharing between a point-to-point primary system (PRS) and a multiuser multi-antenna cellular cognitive radio system (CRS) containing a large number of cognitive users (CUs). The resource sharing optimization problem is formulated by jointly scheduling CUs and adjusting the transmit power at the cognitive base station (CBS). The effect of accessing CUs' spatial channel correlation on the possible transmit power of the CBS is investigated. Accordingly, we provide a low-complexity suboptimal approach termed the semi-correlated semi-orthogonal user selection (SC-SOUS) algorithm to enhance the spectrum efficiency. In the proposed algorithm, CUs that are highly correlated to the information decoding primary receiver (IPR) and mutually near orthogonal are selected for simultaneous transmission to reduce the interference to the IPR and increase the sum rate of the CRS. We further develop a spatial correlation-based resource sharing (SC-RS) strategy to improve energy sharing performance. CUs nearly orthogonal to the energy harvesting primary receiver (EPR) are chosen as candidates for user selection. Therefore, the EPR can harvest more energy from the CBS so that the energy utilization of the network can improve. Besides, zero-forcing precoding and power control are adopted to eliminate interference within the CRS and meet the transmit power constraints. Simulation results and analysis show that, compared with the existing CU selection methods, the proposed low-complex strategy can enhance both the achievable sum rate of the CRS and the energy sharing capability of the network.

• Korean Journal of Cognitive Science
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• v.27 no.2
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• pp.325-353
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• 2016

The visual span refers to the number of letters that can be accurately recognized without moving one's eyes. The size of the visual span is affected by sensory factors such as perimetric complexity, crowding, and mislocation of letters. Korean Hangul utilizes rather unique alphabetic-syllabary writing system, quite different from English and Chinese writing systems. Due to this combinatorial nature of the script, the visual span for Hangul characters can also be affected by the letter type (e.g., CV vs CVCC). The present study examined the effect of syllable complexity on the visual span for Hangul by comparing letter recognition accuracy across four letter type conditions (C only, CV, CVC, and CVCC). We also aimed to determine the meaningful letter type(s) that is associated with differences in reading abilities in Korean. Using a trigram presentation method, we found that overall recognition accuracy declined as syllable complexity increased. However, the visual span for CVC type was greater than that for CV type, suggesting that the effect is not necessarily linear, and that there might be other factors affecting the visual span for these types of letters. C and CV type showed fairly strong positive correlations with reading comprehension, suggesting that these might be the meaningful units for measuring visual span in relating to reading abilities.

• The Journal of the Korea Contents Association
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• v.12 no.3
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• pp.171-180
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• 2012

The purpose of this study is to analyze the relationship between the self-leadership and the cognitive flexibility of the university students who are majoring in dance to provide useful information in the field of dance instruction. Participants were the students majoring in dance who are enrolled in the dance department of the four-year universities nationwide and 282 data have been used for the final analysis. The analytical method for verification of hypothesis was multiple regression analysis to be performed at a significance level of ${\alpha}$=.05. As the result, the following conclusions have been gained. First, the constructive thinking pattern among the sub-factors of self-leadership had a positive influence on the flexibility of preferred varieties which is a sub-factor of cognitive flexibility. However, the behavior-oriented and natural reward self-leadership did not have influence on the diversity preferred flexibility. Second, the natural reward and constructive thinking pattern among the sub-factors of self-leadership have positive influence on the flexibility of preferred complexity which is a sub-factor of cognitive flexibility while the constructive thinking pattern flexibility was shown as exercising a very powerful influence. But the behavior-oriented self-leadership did not have influence on the flexibility of preferred complexity.

• Journal of the Ergonomics Society of Korea
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• v.26 no.4
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• pp.17-24
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• 2007

Analyses of eye tracking and think-aloud protocol data were performed to examine novice-expert differences in perceptual and cognitive aspects of air traffic controllers' situation awareness. In Experiment 1, three groups of field air traffic controllers (experts, intermediates, novices) were asked to perceive situations that were manipulated by situation complexity. In Experiment 2, protocol analysis for previous situation awareness tasks was performed to extract different task models and strategy models as a function of expertise. Then delayed-recall task and interviews about air control plans for the recalled situations were also executed. Results showed that expert controllers concentrate only on several critical features and have their own strategies to reduce mental workloads.

• Korean Journal of Child Studies
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• v.15 no.1
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• pp.23-35
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• 1994

This paper investigated children's learning process concerning age and gender, two of the most apparent social roles. The subjects of the study were 72 Korean preschool children between three to five years of age. The Study was designed to examine problems of developmental sequence and horizontal decalage in understanding of these social roles. Two five-step knowledge sequences of age growth and sex constancy were administered utilizing skill theory (Fischer, 1980). Each step in a sequence had different stories of age or sex role with increasing cognitive complexity, but the two sequences were equivalent in complexity. The children were tested under two different assessment conditions:high support condition of elicited imitation and low support condition of free play and the best story. The findings show that, the understanding of age and sex roles develops through the predicted five-step sequences. The understanding of age role seems to develop earlier than that of sex role although the developmental patterns of the two roles are similar. Variations in the children's performances under different conditions were dramatic, especially for the older children.

• Research in Mathematical Education
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• v.22 no.2
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• pp.123-134
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• 2019

In this paper, we articulate what is a lesson for all learners with different cognitive levels and what kind of teaching practices are required to implement this type of lesson. For all learners' own sense-making, open-ended tasks are the primary sources to bring their various mathematical ideas. These tasks can be meaningfully implemented by appropriate teaching practices: providing enough time (for thinking deeply and for preparing a reply), acting intentionally (alternative wrapping up activities and appointment of a struggling student), and cultivating collaborative classroom norms (respecting peer's thinking and learning from peers). This exploratory study has the potential to help practitioners and researchers understand the complexity of the work of teaching and clarify how to deal with such complexity.

• ETRI Journal
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• v.42 no.6
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• pp.846-858
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• 2020

The non-orthogonal multiple access (NOMA) technique offers throughput improvement to meet the demands of the future generation of wireless communication networks. The objective of this work is to further improve the throughput by including an underlay cognitive radio network with an existing multi-carrier NOMA network, using cooperative communication. The throughput is maximized by optimal resource allocation, namely, power allocation, subcarrier assignment, relay selection, user pairing, and subcarrier pairing. Optimal power allocation to the primary and secondary users is accomplished in a way that target rate constraints of the primary users are not affected. The throughput maximization is a combinatorial optimization problem, and the computational complexity increases as the number of users and/or subcarriers in the network increases. To this end, to reduce the computational complexity, a dynamic network resource allocation algorithm is proposed for combinatorial optimization. The simulation results show that the proposed network improves the throughput.

• Korean Journal of Cognitive Science
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• v.3 no.2
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• pp.271-289
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• 1992

In this paper,a cursive on-line Hangul recognition system which permits cursive writing between graphemes is presented.In general,the recognition of cursive Hangul writing has a difficulty of graheme segmentation and a complexity in matching procedure due to the increasing number of character candidates.To manage efficiently these problems,we propose a double segmentation method.Based on this segmentation,a recognition algorithm based on the line segment matching is proposed.Through the experimental result,it is show that the proposed recognition method is suitable for the cursive Hangul writings.