• 한국항공운항학회지
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• 제22권4호
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• pp.42-55
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• 2014

The purpose of this research was to identify expertise in ait traffic control by using cognitive skill analysis for novices and experts in routine and non-routine situations. The result of study was to understand expertise in air traffic control tasks in terms of what cognitive processes are responsible for the expert's high performance levels. The problem solving task was difficult for novices, but performed relatively automatically by experts in a routine situation. The difficulty could indicate the presence of controlled processing. Rather than rules and strategies, novices focused more on environmental factors, which merely increase cognitive load. In a non-routine situation, novices showed that they did not categorize the information consistently and alternative resources were not available for them. Experts, however, performed automatically a task by arranging and organizing information related to problem solving components in contexts without regard to a routine and non-routine situation. Especially experts developed a stable representation and directed alternative resources for air traffic flow and efficiency. Based on the results, cognitive processes of experts could be useful to understand expert performance and analyze the learning process, which imply the necessity of developing expertise systematically.

• 농촌의학ㆍ지역보건
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• 제32권1호
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• pp.1-12
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• 2007

Objectives: This study was performed to provide the fundamental data available in the field of the elderly health of the low-income bracket by researching and comparing related factors for the assessment of the degree of depression and cognitive function between elderly welfare recipients and non-elderly welfare recipients. Methods: The study subjects, 402 elderly person over 65-year-old in Daejeon were interviewed, during the two-month from May to June 2006, about their general characteristics, depression and cognitive function. Results: elderly welfare recipients was higher than non-elderly welfare recipients in degree of depression on the other hand, in cognitive function is lower. Also, the depression and cognitive function were related with not only socio-demographic characteristics like the age, the degree of education, the presence of spouse or not and the health status but also health behavior characteristics like the sleeping time, the drinking and the exercise. Conclusions: The project of health promotion and programs that can improve the related factors to the depression and cognitive function for elderly welfare recipients should be developed and practiced.

• 한국통신학회논문지
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• 제34권2B호
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• pp.178-187
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• 2009

인지 라디오 (Cognitive Radio: CR)란 할당된 주파수 대역 중에 우선 사용자가 사용하지 않는 유휴 주파수를 사용하여 주파수의 효율을 극대화 시킬 수 있는 기술이다. 그러나 CR 환경에서는 우선 사용자에 대한 간섭이 없는 상태에서만 자원을 공유하는 매우 엄격한 제한을 가지고 있다. 더욱이 유휴 주파수 자원은 시간, 주파수 별로 변화하기 때문에 이를 효율적으로 사용하기 위한 스케줄링 알고리즘이 필수적이다. 그러나 기존의 우선 사용자들만 존재하는 무선 통신 환경에서 적용되던 스케줄링 알고리즘은 CR 환경에 대한 제약 조건이 반영되지 않아 유휴 주파수 자원 사용의 효율성 문제가 발생한다. 이에 본 논문에서는 무선 채널 상태와 우선 사용자 출현 확률을 고려하는 하향링크 스케줄링 알고리즘을 제안한다. 제안 스케줄링 알고리즘의 성능 평가를 위해 모의실험을 수행하였으며, 그 결과 제안 알고리즘이 우선 사용자 출현 확률을 고려하지 않는 하향링크 스케줄링 알고리즘에 비해 우수한 성능이 제공됨을 확인하였다.

• Journal of Communications and Networks
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• 제17권4호
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• pp.440-448
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• 2015

In this paper, we study the problem of selfish behavior of secondary users (SUs) based on cognitive radio (CR) with the presence of primary users (PUs). SUs are assumed to contend on a channel using the carrier sense multiple access with collision avoidance (CSMA/CA) and PUs do not consider transmission of SUs, where CSMA/CA protocols rely on the random deference of packets. SUs are vulnerable to selfish attacks by which selfish users could pick short random deference to obtain a larger share of the available bandwidth at the expense of other SUs. In this paper, game theory is used to study the systematic cheating of SUs in the presence of PUs in multichannel CR networks. We study two cases: A single cheater and multiple cheaters acting without any restraint. We identify the Pareto-optimal point of operation of a network with multiple cheaters and also derive the Nash equilibrium of the network. We use cooperative game theory to drive the Pareto optimality of selfish SUs without interfering with the activity of PUs. We show the influence of the activity of PUs in the equilibrium of the whole network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권2호
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• pp.355-370
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• 2014

Cooperative spectrum sensing has been considered as a promising approach to improve the sensing performance in distributed cognitive radio networks. However, there may exist some selfish secondary users (SUs) who are unwilling to cooperate. The presence of selfish SUs could cause catastrophic damage to the performance of cooperative spectrum sensing. Following the social perspective, we propose a Social Tie-based Incentive Scheme (STIS) to deal with the selfish problem for cooperative spectrum sensing in distributed cognitive radio networks. This scheme inspires SUs to contribute sensing information for the SUs who have social tie but not others, and such willingness varies with the strength of social tie value. The evaluation of each SU's social tie derives from its contribution for others. Finally, simulation results validate the effectiveness of the proposed scheme.

• 생물정신의학
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• 제23권3호
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• pp.80-88
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• 2016

Vascular dementia is a very frequent form of dementia. Debates over classification and diagnostic criteria, and controversy over identifiable treatment targets will continue until distinct pathophysiological mechanism of vascular dementia is found. Clinical diagnostic criteria are sufficiently strong to be useful for clinical trials, but need further refinement. Cognitive changes in vascular dementia are more variable than other disorders, and are dependent on the vascular pathology. Accurate diagnosis of vascular dementia is known to need the presence of reliable cerebrovascular disease on brain imaging. Although it seems obvious that cerebrovascular disease causes pathological damage and impaired cognition, it is very difficult to find the accurate contribution of cerebrovascular pathology to cognitive decline. Most studies have shown a small but significant benefit of cholinesterase inhibitors on cognition, the significance of this effect has been slight and benefits on global functioning, activities of daily living, and behaviour have not been consistently reported. Management of vascular dementia should focus on identifying and managing vascular risk factors.

• 기독교교육논총
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• 제70권
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• pp.303-337
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• 2022

본 연구의 목적은 학습자간 대면 접촉이 없는 환경에서 교수-학생간 실재감 인식을 높일 수 있는 상호작용적 요소를 강화한 Ontact PBL을 구현하여 이제 갓 대학을 입학한 대학생들이 1학년 1학기 교양 교과목에서 비대면 수업 환경에서 학습자가 중심의 협력학습을 수행해야 하는 PBL 수업을 통해 교수실재감 및 학습실재감이 향상되었는지 살펴보며, 실재감이 향상된 수업 사례를 제시하고자 하는 연구이다. 이 수업은 2021년 1학기 Ontact PBL을 설계 및 개발하여 운영하였으며, 해당 수업을 수강한 학생들을 대상으로 교수실재감 및 학습실재감을 진단하여 실제로 수업을 통해 교수실재감은 평균 0.95점 유의미하게 향상되어, 학습실재감보다 많이 향상되었고, 이는 학생들의 수업에 대한 성찰 저널에서도 관련 의견이 많아 교수실재감 향상에 효과적임을 알 수 있었다. 더불어 학습실재감도 효과가 있었는데, 학습실재감의 하위요소인 감성적 실재감은 0.7점, 사회적 실재감은 0.5점, 인지적 실재감은 0.6점 가량 유의미하게 향상됨을 확인하였다. 학습실재감 또한 학생들의 수업에 대한 성찰을 확인하여, Ontact PBL이 실재감 향상에 효과가 있다고 판단할 수 있었다. 향후 Ontact PBL의 실재감 향상 요인 연구, Ontact PBL을 통한 학생 역량 향상 연구 등을 후속 연구로 제안한다.

• Journal of Communications and Networks
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• 제16권5호
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• pp.485-492
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• 2014

Spectrum sensing for cognitive-radio applications may use a matched-filter detector (in the presence of full knowledge of the signal that may be transmitted by the primary user) or an energy detector (when that knowledge is missing). An intermediate situation occurs when the primary signal is imperfectly known, in which case we advocate the use of a linear-quadratic detector. We show how this detector can be designed by maximizing its deflection, and, using moment-bound theory, we examine its robustness to the variations of the actual probability distribution of the inaccurately known primary signal.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권2호
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• pp.371-388
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• 2014

Cognitive Radio (CR) has been recently proposed as a promising technology to remedy the problems of spectrum scarcity and spectrum underutilization by enabling unlicensed users to opportunistically utilize temporally unused licensed spectrums in a cautious manner. In Cognitive Radio Ad Hoc Networks (CRAHNs), data routing is one of the most challenging tasks since the channel availability and node mobility are unpredictable. Moreover, the network performance is severely degraded due to large numbers of path failures. In this paper, we propose the Fault-Tolerant Cognitive Ad-hoc Routing Protocol (FTCARP) to provide fast and efficient route recovery in presence of path failures during data delivery in CRAHNs. The protocol exploits the joint path and spectrum diversity to offer reliable communication and efficient spectrum usage over the networks. In the proposed protocol, a backup path is utilized in case a failure occurs over a primary transmission route. Different cause of a path failure will be handled by different route recovery mechanism. The protocol performance is compared with that of the Dual Diversity Cognitive Ad-hoc Routing Protocol (D2CARP). The simulation results obviously prove that FTCARP outperforms D2CARP in terms of throughput, packet loss, end-to-end delay and jitter in the high path-failure rate CRAHNs.

• 한국치위생학회지
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• 제15권2호
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• pp.217-223
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• 2015

Objectives: The purpose of this study is to investigate cognitive function, performance of activities of daily living, and recognition on oral health with the cognitive function testto dementia or dementia-suspected patients in the outpatients. Methods: The subjects were 94 dementia or dementia-suspected patients visiting C University hospital for the dementia test. Study instruments included Korea Mini-Mental State Examination KMMS, The Bayer-Activities of Daily Living Scale; B-ADL, Seoul-Instrumental Activities of Daily Living; S-IADL, Global Deterioration Scale; GDS, Korean Dementia Screening Questionnaire; KDSQ, and underlying diseases. Results: Dementia or dementia-suspected patients were 42 by KMMSE test, 25 patients had impaired functioning of daily living by B-ADL test, 27 patients showed the presence of depression by GDS test, and 45 patients showed impaired functioning of daily living. There was a statistically significant difference in the subjective recognition on oral health conditions. There was a statistically significant difference in the subjective recognition on oral health conditions by ADL. There was a positive correlation between the cognitive function and ADL performance. Higher cognitive function is proportional to ADL performance. Conclusions: The cognitive function was closely associated with ADL and subjective oral health conditions.