• Journal of Internet Computing and Services
• /
• v.12 no.3
• /
• pp.77-88
• /
• 2011

In distributed cognitive radio networks, cognitive radio devices which perform the channel sensing individually, are seriously affected by radio channel environments such as noise, shadowing and fading such that they can not property satisfy the maximum allowable interference level to the primary user. In the paper, we propose a Q-learning based channel access scheme for cognitive radios so as to satisfy the maximum allowable interference level to the primary user as well as to improve the throughput of cognitive radio by opportunistically accessing on the idle channels. In the proposed scheme, the pattern of channel usage of the primary user will be learned through Q-learning during the pre-play learning step, and then the learned channel usage pattern will be utilized for improving the sensing performance during the Q-learning normal operation step. Through the simulation, it is shown that the proposed scheme can provide bettor performance than the conventional energy detector in terms of the interference level to primary user and the throughput of cognitive radio under both AWGN and Rayleigh fading channels.

• Physical Therapy Korea
• /
• v.21 no.3
• /
• pp.80-88
• /
• 2014

Previous studies have reported that decreased cognitive ability has been consistently associated with significant declines in performance of one or both tasks under a dual-task walking condition. This study examined the relationship between specific cognitive abilities and the dual-task costs (DTCs) of spatio-temporal gait parameters in stroke patients. The spatio-temporal gait parameters were measured among 30 stroke patients while walking with and without a cognitive task (Stroop Word-Color Task) at the study participant's preferred walking speed. Cognitive abilities were measured using Computerized Neuropsychological Testing. Pearson's correlation coefficients (r) were calculated to quantify the associations between the neuropsychological measures and the DTCs in the spatio-temporal gait parameters. Moderate to strong correlations were found between the Auditory Continuous Performance test (ACPT) and the DTCs of the Single Support Time of Non-paretic (r=.37), the Trail Making A (TMA) test and the DTCs of Velocity (r=.71), TMA test and the DTCs of the Step Length of Paretic (r=.37), TMA test and the DTCs of the Step Length Non-paretic (r=.36), the Trail Making B (TMB) test and the DTCs of Velocity (r=.70), the Stroop Word-Color test and the DTCs of Velocity (r=-.40), Visual-span Backward (V-span B) test and the DTCs of Velocity (r=-.41), V-span B test and the DTCs of the Double Support Time of Non-paretic (r=.38), Digit-span Forward test and the DTCs of the Step Time of Non-paretic (r=-.39), and Digit-span Backward test and the DTCs of the Single Support Time of Paretic (r=.36). Especially TMA test and TMB test were found to be more strongly correlated to the DTCs of gait velocity than the other correlations. Understanding these cognitive features will provide guidance for identifying dual- task walking ability.

• Journal of Korean Institute of Industrial Engineers
• /
• v.26 no.1
• /
• pp.9-16
• /
• 2000

In these days, the interior interface design for vehicle drivers was recognized as important affairs. Thereby, many studies are being performed for this. These studies emphasize the physical factors and usability of human, but those for the cognitive factors are not enough. Cognitive factors are very important elements to determine the drivers' performance. In this study, it was studied about the method to extract a driver's cognitive map on IP(Instrument Panel) in dynamic situation, and BPM(Blind-Pointing Method) was proposed for this. The BPM is the method to extract a cognitive map by subject's pointing action under the blinded condition. The experiment was conducted to validate compatibility of BPM as the method to extract a cognitive map. In the experiment, subjects were divided in two groups, the first group of subjects has their own vehicle and driver license, and the second group of subjects doesn't have own vehicle but has driver license. The result shows that the IP form of cognitive map is not different between two groups, and BPM is the compatible method to extract a cognitive map.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.6 no.3
• /
• pp.111-121
• /
• 2007

In this paper, we propose a TH-Multiband-UWB system through pulse shaping to fit in domestic UWB spectrum regulation. We propose the transmission pulse of Multi-Carrier type for pulse shaping and use Cognitive Radio to detect interfering frequency. We use Genetic Algorithm in Cognitive Radio's calculation propose and propose solution of interference problem between TH-UWB using Cognitive Radio and typical MB-OFDM UWB system or other communication systems. In this paper, we explain how Cognitive Engine detects the interfering frequency. The technique of TH-Multiband-UWB system using Cognitive Radio shows a good performance in interference condition.

• Journal of The Korean Society of Integrative Medicine
• /
• v.9 no.4
• /
• pp.49-58
• /
• 2021

Purpose : This study investigates the effects of the application of traditional occupational therapy and the korean computerized cognition training system on the cognitive function and performance of daily activities of stroke patients with cognitive impairment. Methods : From inpatients referred for rehabilitation treatment at L Rehabilitation Hospital located in Busan, 20 patients diagnosed with stroke from April 05. 2021 to May 02. 2021 (study period) were selected, They were divided into two, an experimental group consisting of 10 subjects who underwent a computerized cognitive rehabilitation program and traditional occupational therapy in combination and a control group of 10 subjects who underwent traditional occupational therapy alone. In order to measure the cognitive function of the subjects before the intervention, two assessment tests were conducted: a Neurobehavioral Cognitive Status Examination (NCSE), which evaluates stroke-related cognitive ability, and a Functional Independence Measure (FIM) test, which evaluates life activities. Then, both groups received a total of 20 training sessions at 30 minutes per session, five times a week for four weeks. Results : A statistically significant difference was found in cognitive function between before and after the cognitive training for both the experimental group and the control group. For the FIM scores, statistically significant differences were observed after intervention in the categories of handling personal matters and social cognition, and in the total score. The average scores of the remaining items also improved. Conclusion : The results of this study showed that both the computerized cognition rehabilitation program and the traditional occupational therapy had a positive effect on the improvement of cognitive function in stroke patients.

• Industry Promotion Research
• /
• v.9 no.3
• /
• pp.41-55
• /
• 2024

This study analyzes the impact of digital strategy on firm performance through relational behavior, cognitive dimensions, and continuous digital transformation based on social capital theory. The research model was tested using data collected from a survey of 300 domestic corporate employees who have worked for over a year, conducted from February 20 to 23, 2024, using Smart PLS 4.0. The key findings of the study are as follows: First, it was confirmed that digital strategy plays a crucial role in promoting cooperation and interaction within the organization, enhancing members' understanding and perception of digital technology, and strengthening the firm's competitiveness through continuous change and innovation. Second, continuous digital transformation and cognitive dimensions positively impact firm performance, while the influence of relational behavior dimensions was found to be insignificant. These findings suggest that digital strategy can significantly affect firm performance by fostering interaction and perception changes within the organization, beyond mere technology adoption, and provide strategic implications for Korean firms to effectively pursue digital transformation.

• The Journal of Korean society of community based occupational therapy
• /
• v.5 no.2
• /
• pp.11-21
• /
• 2015

Objective : We tried to know the effect on the ability of work performance, cognitive, balance, depression, ability of daily living, the quality of life, and time usage after applying the group cognitive therapy that based on lifestyle redesign to dementia elderly. Methods : We performanced the group cognitive therapy that based on lifestyle redesign to 15 dementia elderly for 12weeks by total 5 steps. We evaluated the ability of work performance(COPM), cognitive(MMSE-DS), balance(BBS), depression(GDS-K), ability of daily living(MBI), the quality of life(GQOL-D), and time usage(OQ) of before and after the programme. Results : There was a significant difference of the ability of work performance, balance, the quality of life, and locomotive area of time usage after applying the group cognitive therapy that based on lifestyle redesign to dementia elderly. Conclusion : The group cognitive therapy that based on lifestyle redesign programme is effective for satisfaction of work performance and improvement of the quality of life and balance ability. The programme is also effective for locomotive area of time usage. We found out the effect of the programme in variety of the life of dementia elderly.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.16 no.27
• /
• pp.105-111
• /
• 1993

Human works shift its roll from physical condition to the system supervisory control task In this paper safety-presentation configuration is discussed instead of well-known fault-warning configuration. Of paticular interest was the personal factor which include the cognitive process. Through a performance between each person information processing(d') and decision process($\beta$) was pointed out to explain the sensitivity of personal cognitive process. Impact of uncertainty effect the supervisor having doubt situations. These facts are released by the use of flat fuzzy number of $\beta$ and its learning rate R.

• International Journal of Advanced Culture Technology
• /
• v.1 no.2
• /
• pp.18-23
• /
• 2013

In this paper, we consider the problem of designing optimal sensing time and the minimization of energy consumption in the Cognitive radio Network. Trade-off between throughput and the sensing time are observed, and the equations are derived for the optimal choice of design variables. In this paper, we also look at the optimization problem involving all the design parameters together. The advantages of the proposed scheme for the spectrum sensing and access process are shown through simulation.

• Journal of Communications and Networks
• /
• v.16 no.3
• /
• pp.301-304
• /
• 2014

This paper proposes accurate interference probability and bit error rate formulas for cognitive relay networks with underlay spectrum sharing and channel estimation error (CEE). Numerous results reveal that the CEE not only degrades the performance of secondary systems (SSs) but also increases interference power caused by SSs to primary systems (PSs), eventually unfavorable to both systems. A solution to further protect PSs from this effect through reducing the power of secondary transmitters is investigated and analyzed.