• Journal of Biomedical Engineering Research
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• v.43 no.1
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• pp.52-60
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• 2022

Purpose: For now, cognitive load is assessed based on survey-based methods, which can be difficult to track the amount of cognitive load in real-time. In this study, we investigated the difference in electrophysiological activation due to different levels of cognitive load not only at sensor-level but also at source-level using electroencephalogram that might be potentially used for quantitative cognitive load evaluation. Materials and Methods: In this study, ten healthy subjects (mean age 24.3 ± 2.1, three female) participated the experiment. All participants performed 4 sessions of n-back task in different difficulties: 0-, 1-, 2-, and 3-back during electroencephalogram recording. For sensor-level analysis, we calculated the event-related potential and event-related spectral perturbation while low resolution brain electromagnetic tomography (LORETA) to estimate the source activation. Each result was compared between different workload conditions using statistical analysis. Results: Statistical results revealed that the accuracy of the task performance was significantly different between different cognitive loads (p = 0.018). The post-hoc analysis confirmed that the accuracy of the 3-back task was significantly decreased compared to 1-back condition (p = 0.018), but not with 2-back condition (p = 0.180). ERP results showed that P300 target amplitude between 1-back and 3-back had a marginal difference in Cz (p = 0.059) and Pz(p = 0.093). A significant inhibition in Cz high-beta activation (p = 0.017) and decrease in source activation of right parahippocampal gyrus was found in 3-back condition compared to 1-back condition (p < 0.05). Conclusion: In this study, we compared the sensor- and source-level differences in electroencephalogram between different levels of cognitive load, that were found to be in line with the previous reports related to cognitive load evaluation. We expect that the outcome of the current study can be used as a feature to establish a quantitative cognitive load assessment system.

• Spatial Information Research
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• v.14 no.4 s.39
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• pp.433-449
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• 2006

Two primary objectives of this study were to determine important personal factors in performing cognitive distance mapping, and to understand how human's cognitive distance mapping capabilities were influenced by reference and subjects' locations using Global Positioning System (GPS). Undergraduate and graduate students at the University of Kansas, USA were interviewed and surveyed throughout the campus area giving them a paper-and-pencil test. Study results showed that females had more accurate cognitive mapping capability than males regardless of ethnic background and academic levels. Generally, subjects with longer affiliation with the university, higher ages and academic levels had less variability in their mapping accuracy. Subjects tended to more accurately map the target locations closer to the reference points than those located farther away, and subjects who were closer to a reference point performed their distance mapping better than those farther away. A correlation analysis reported that male subjects used reference-to-target and subject-to-reference distances more sensitively than females to estimate the locations of the targets. This result indicates that males might have used the reference point-based map scale more strenuously than females.

• Journal of The Korean Society of Integrative Medicine
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• v.8 no.2
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• pp.89-95
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• 2020

Purpose : This study aims to evaluate the correlation of cognitive function, activities of daily living (ADL), and driving performance in stroke hemiplegic patients residing in Korea. Methods : Subjects of the study were 18 stroke hemiplegic patients admitted to hospitals situated in Seoul. A clock drawing test (CDT), a modified Barthel index (MBI), and a virtual reality driving simulator (Eca faros-driving simulator) were used to examine their cognitive function, their ADL ability, and their driving skills, respectively. Results : Driving skills of stroke hemiplegic patients were shown to be associated with the CDT evaluation tool (r=-.777) (p<.001), but they were found to have any correlation with MBI (r=-.022) (p>.05). Additionally, an individual's CDT showed that the driving simulator evaluation result (pass/fail) could be discriminated with a sensitivity of 100.0 %, a specificity of 40.0 %, and an accuracy of 66.7 %. The result confirmed that the CDT is a useful evaluation tool for screening driving ability in people with stroke. But the MBI did not show any significant results (sensitivity of 62.5 %, specificity of 40.0 %, and predicted the results of the simulator with 50.0 % of accuracy) (p>.05). Conclusion : This study shows that cognitive function influences the driving performance in people with stroke. Driving skills of stroke hemiplegic patients are seen to be highly related to CDT. In the field of driving rehabilitation, these findings could be useful for evaluating driving skills relating to CDT. Furthermore, the study results will set a guideline for domestic occupational therapists to use the evaluation tool for assessing driving abilities in people with stroke.

• Korean Journal of Cognitive Science
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• v.30 no.4
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• pp.175-197
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• 2019

Writing is an activity known to enhance higher level thinking. It allows the writer to utilize, apply, and actively expand the acquired knowledge. One way to increase writing activity in classroom setting is to use peer assessment. In this study, we sought to increase the accuracy of peer assessment by having students discuss about the scoring rubric or by referring to an expert's assessment. One hundred and fifty college students participated in the experiment. In the group that referred to the expert's assessment, the accuracy of peer assessment increased when the same piece of writing was evaluated; however, no such increase was observed when another piece of writing was assessed. On the other hand, in the group that discussed about the scoring rubric, the accuracy of peer assessment remained the same when the same piece of writing was evaluated, but increased when another piece of writing was assessed. Also, in the discussion group, the accuracy increased in proportion to the number of comments during the discussion. The results suggest that active and voluntary participation of students increase the accuracy of peer assessment.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.2
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• pp.104-109
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• 2016

In this paper, a localization method for multiple robots based on Bayesian inference is proposed when multiple robots adopting multi-RAT (Radio Access Technology) communications exist in cognitive radio networks. Multiple robots are separately defined by primary and secondary users as in conventional mobile communications system. In addition, the heterogeneous spectrum environment is considered in this paper. To improve the performance of localization for multiple robots, a realistic multiple primary user distribution is explained by using the probabilistic graphical model, and then we introduce the Gibbs sampler strategy based on Bayesian inference. In addition, the secondary user selection minimizing the value of GDOP (Geometric Dilution of Precision) is also proposed in order to overcome the limitations of localization accuracy with Gibbs sampling. Via the simulation results, we can show that the proposed localization method based on GDOP enhances the accuracy of localization for multiple robots. Furthermore, it can also be verified from the simulation results that localization performance is significantly improved with increasing number of observation samples when the GDOP is considered.

• Phonetics and Speech Sciences
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• v.5 no.1
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• pp.27-38
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• 2013

Healthcare providers in Korea are using conservative pharmacological treatment for Alzheimer's disease (AD) to delay the progress of the disease or to mitigate its behavioral and neurological symptoms. However, there is a growing need for interventions using practical non-pharmacologic treatment, as the effects of pharmacological treatments has faced limitations. This research provided a cognitive rehabilitation program to 3 AD patients and used a multiple baseline design across subjects to examine the effects. Performing reality orientation therapy (ROT) for 1 cycle (4 weeks) resulted in a slight increase in accuracy and responsiveness on an orientation task, mainly with patients with mild cases of AD. Also, in the sub-domain of the Korean-Mini Mental Status Examination performed to examine changes in cognitive ability, there were minimal changes in place orientation. In functional communication, however, there were no significant differences before and after the intervention. In conclusion, we found that ROT was an effective intervention for improving accuracy and responsiveness in the orientation of patients with mild cases of AD. In future studies, the effect of non-pharmacological interventions can be evaluated more reliably by examining the interaction effects of sample size, length of the intervention, outcome measurements, and pharmacological intervention.

• ETRI Journal
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• v.37 no.3
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• pp.491-501
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• 2015

Spectrum sensing is an elementary function in cognitive radio designed to monitor the existence of a primary user (PU). To achieve a high rate of detection, most techniques rely on knowledge of prior spectrum patterns, with a trade-off between high computational complexity and long sensing time. On the other hand, blind techniques ignore pattern matching processes to reduce processing time, but their accuracy degrades greatly at low signal-to-noise ratios. To achieve both a high rate of detection and short sensing time, we propose fast spectrum sensing with coordinate system (FSC) - a novel technique that decomposes a spectrum with high complexity into a new coordinate system of salient features and that uses these features in its PU detection process. Not only is the space of a buffer that is used to store information about a PU reduced, but also the sensing process is fast. The performance of FSC is evaluated according to its accuracy and sensing time against six other well-known conventional techniques through a wireless microphone signal based on the IEEE 802.22 standard. FSC gives the best performance overall.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.1
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• pp.58-73
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• 2014

As is well known, cooperative sensing can significantly improve the sensing accuracy as compared to local sensing in cognitive radio networks (CRNs). However, a large number of cooperative secondary users (SUs) reporting their local detection results to the fusion center (FC) would cause much overhead, such as sensing delay and energy consumption. In this paper, we propose a fast cooperative sensing scheme, called double threshold fusion (DTF), to reduce the sensing overhead while satisfying a given sensing accuracy requirement. In DTF, FC respectively compares the number of successfully received local decisions and that of failed receptions with two different thresholds to make a final decision in each reporting sub-slot during a sensing process, where cooperative SUs sequentially report their local decisions in a selective fashion to reduce the reporting overhead. By jointly considering sequential detection and selective reporting techniques in DTF, the overhead of cooperative sensing can be significantly reduced. Besides, we study the performance optimization problems with different objectives for DTF and develop three optimum fusion rules accordingly. Simulation results reveal that DTF shows evident performance gains over an existing scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.12
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• pp.3266-3285
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• 2023

With the popularity of online learning, intelligent tutoring systems are starting to become mainstream for assisting online question practice. Surrounded by abundant learning resources, some students struggle to select the proper questions. Personalized question recommendation is crucial for supporting students in choosing the proper questions to improve their learning performance. However, traditional question recommendation methods (i.e., collaborative filtering (CF) and cognitive diagnosis model (CDM)) cannot meet students' needs well. The CDM-based question recommendation ignores students' requirements and similarities, resulting in inaccuracies in the recommendation. Even CF examines student similarities, it disregards their knowledge proficiency and struggles when generating questions of appropriate difficulty. To solve these issues, we first design an enhanced cognitive diagnosis process that integrates students' affection into traditional CDM by employing the non-compensatory bidimensional item response model (NCB-IRM) to enhance the representation of individual personality. Subsequently, we propose an affection-enhanced personalized question recommendation (AE-PQR) method for online learning. It introduces NCB-IRM to CF, considering both individual and common characteristics of students' responses to maintain rationality and accuracy for personalized question recommendation. Experimental results show that our proposed method improves the accuracy of diagnosed student cognition and the appropriateness of recommended questions.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.30 no.4
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• pp.157-173
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• 2019

Due to the fact that cognitive authority influences an individual's thoughts so that a given information is perceived as appropriate, people evaluate information based on their cognitive authority. The purpose of the present study is to examine the perception of the cognitive authority of online information sources used by college students to carry out their academic tasks, and to determine whether such perceptions affect the quality assessment of information sources, such as webpages, e-journals, and Wikipedia,. Specifically, we measured how cognitive authority, which were formed by the author, the surface, and the content of an information source influenced its accuracy, usefulness, completeness, and expertise. For this purpose, online surveys were conducted with college students, and 172 valid responses were obtained. Findings indicated that all the characteristics that formed the cognitive authority of an information source had significant impacts on its accuracy, usefulness, completeness, and expertise. The study suggests academic implications that confirm the associations between cognitive authority and credibility of information in the context of online information sources. Furthermore, the study provides practical implications that system developers or operators of information sources need to consider diverse factors that affect their cognitive authority to promote users' trust on the information that they deliver.