• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.2
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• pp.1-8
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• 2012

We propose a new frame length control scheme for cognitive radio systems. In the proposed algorithm, the property that the probability of a primary packet arrival continually increases as time elapses during the primary user's idle period is utilized. When reducing the secondary frame length in accordance with the increasing primary packet arrival probability, spectrum sensing is conducted more frequently as time elapses and the primary packet arrival is detected more quickly. We obtain the optimal frame lengths by maximizing the secondary throughput while satisfying the interference constraint. Numerical results show a significant throughput enhancement via the frame length control.

• Journal of Digital Convergence
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• v.13 no.11
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• pp.205-216
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• 2015

The purpose was to compare the ethical knowledge, values and class satisfaction by students' cognitive style to develop the convergent nursing ethic class considering cognitive style. Questionnaires were collected from 149 freshmen after 12 hours classes for four weeks from October 1st to 30th 2013. Group Embedded Figure Test was used as a cognitive style measurement tool. 62.4% of them were field-dependent. There was a significant difference in cognitive style and ethical knowledge according to high school division. The ethical value was different significantly according to the nursing science satisfaction. Class satisfaction was different significantly according to reason for applying to nursing and nursing science satisfaction. There were no significant differences in ethical knowledge and values by cognitive style. Class satisfaction was higher in field-dependent students. This conclusion will give baseline data to develop nursing education program based on cognitive style.

• Journal of Educational Research in Mathematics
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• v.24 no.2
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• pp.125-143
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• 2014

In this study, we analyzed a mathematical discussion in the Calculus II course of the Gifted Science Academy and individual interviews to determine the relationship between cognitive conflicts and commognitive conflicts. The mathematical discussion began with a question from a student who seemed to have a cognitive conflict about the osculating plane of a space curve. The results indicated that the commognitive conflicts were resolved by ritualizing and using the socially constructed knowledge, but cognitive conflicts were not resolved. Furthermore, we found that the cause of the cognitive conflict resulted from the student's imperfect analogical reasoning and the reflective discourse about it could be a learning opportunity for overcoming the conflict. These findings imply that cognitive conflicts can trigger the appearance of commognitive conflicts, but the elimination of commognitive conflicts does not imply that cognitive conflicts are resolved.

• Journal of Digital Convergence
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• v.17 no.2
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• pp.283-292
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• 2019

The loss of semantic knowledge and impairments in semantic associations by semantic category is gaining increasing attention, as indicators of early-stage cognitive decline. As such, we assigned semantic association task (SAT) to normal elderly (NE) and those with subjective memory impairment (SMI) or mild cognitive impairment (MCI) to examine their performance by semantic subcategories and the differences in error patterns. We found a significant difference in the number of correct response and reaction time under the SAT categories among the three groups, with the highest performance observed in 'function' and the lowest performance in 'superordinate' and 'part/whole'. Moreover, the error frequency was the lowest in NE, followed by those with SMI and MCI, with the latter two groups showing a significant increase in no-response. Our findings demonstrate the varying extent and process of impairments in the semantic network by category over different stages of cognitive decline. Thus, we proposed SAT performance as an indicator to detect and follow-up on cognitive decline in elderly with cognitive disorder.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1D
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• pp.65-72
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• 2011

When an expressway intersects another expressway, a unique connector needs to be designed between the two consecutive exit ramps. In such a case, it is important to design a connector such that there is enough distance for drivers to find their way safely. A current design manual in Korea prescribes the minimum length of the connector as 240 m. In this research, we have suggested a method for calculating the minimum length of a connector in order to check the feasibility of the currently prescribed length. For this purpose, we have attempted to determine the total perception-reaction time and lane-changing time required by a driver. For determining the driver's perception-reaction time, we have used the driver's decision time in addition to the conventional 2.5 s of perception-reaction time for stopping sight distances. We have considered both the design speed and the average travel speed for the calculation of the length. To evaluate the accuracy of the new method, we have chosen four sites on expressways for which relatively high accident rates were recorded. As a result, we could verify that the current limit (240 m) was sufficient for drivers to be able to change lanes in the given specific geometry. However, the prescribed limit should be revised in case the drivers' decision time is considered to be their perception-reaction time. All new approaches for calculating the ideal length of a connector have been carried out by taking into account the design speed as well as the average travel speed. Owing to the characteristics of the specific geometry for two consecutive exit ramps and the large difference between the design speed and the average travel speed in the objective areas, it is more realistic to use the proposed method by keeping the decision time equal to a driver's perception-reaction time, in order to determine the ideal distance that should be maintained between two consecutive exit ramps.

• Korean Journal of Cognitive Science
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• v.18 no.3
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• pp.285-303
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• 2007

Transient attention impairs observers' temporal resolution in a cued location. This detrimental effect of attention was ascribed to inhibitory connections from parvocellular to magnocellular neurons [1]. Alternatively, the difficulty might arise because attention facilitates the temporal summation of two successive stimuli. The current study examined this hypothesis by manipulating the luminance polarity of the stimuli against a background. Attention should not modulate temporal summation of two anti-polar stimuli because these are processed in separate channels. Indeed, observers judged the temporal order of two successive stimuli better in the cued location than in the uncued location when the stimuli were opposite in polarity, but temporal resolution was worse in the cued location when the stimuli had the same polarity. Thus, attentional effects on temporal resolution may be attributed to temporal summation rather than parvocellular inhibition of magnocellular activity.

• Korean Journal of Optics and Photonics
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• v.27 no.6
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• pp.212-217
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• 2016

In connection-oriented data-transport services, data loss can occur when the service experiences a problem on its end-to-end path. To promptly resolve this problem, the data-switching systems providing the service should quickly modify their internal configurations distributed among different places in each system. This is performed through a sequence of problem (event) recognition, sharing, and handling procedures among multiple control processors in the system. This paper proposes a method for event sharing and messaging between control processors, to improve the time determinacy of event processing. This method simplifies runtime event sharing and minimizes the time variability caused by the event data, resulting in a decrease in the latency time in processing global events. The proposed method lessens the latency time of global event processing by about 40%, compared to general methods, for 738 internal path changes.

• The Journal of the Korea Contents Association
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• v.17 no.1
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• pp.402-411
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• 2017

To develop a more efficient computer-based empathy program that enables medical students to increase their empathy levels, and to test its applicability to medical students. We developed PACP (the Pain Assessment Computer Program) for measurement of medical students' levels of recognition of another's pain. An empathy questionnaire was administered to 145 medical students before and after the PACP. In the high empathy group, the scores for cognitive empathy increased significantly after completion of the PACP, while affective empathy scores showed no significant change. In contrast, in the low empathy group, both cognitive and affective empathy scores increased significantly after the PACP. The PACP effectively increased cognitive empathy for the high empathy group, and increased both cognitive and affective empathy, particularly for the low empathy group. Given the fact that existing empathy education programs are time-consuming and costly, and the demand for more efficient empathy education is high, the PACP as a useful tool can be applicable to medical students, particularly those with low empathy in order to enhance their empathic abilities within a short period of time.

• Journal of Nutrition and Health
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• v.41 no.8
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• pp.718-732
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• 2008

The purpose of this study was to investigate nutrients or food factors related to cognitive function of elderly having Alzheimer's disease. In this study 38 subjects who were over 65 years old have participated in dementia clinic at A medical center. After they were diagnosed to Alzheimer's Disease (AD) through blood analysis, neuropsychological test, brain image and interview by medical specialist, we examined for their general information, anthropometry, blood pressure and dietary intakes. Dietary intakes were investigated using the 24-hour recall record. Energy intake was adequate and the energy composition of carbohydrate, protein and fat was 60.8 : 16.2 : 23.0, but dietary intakes of calcium, vitamin A and folate were less than 75% of the recommended intake levels for Koreans. The multiple regression analysis adjusted with age, sex and educational level showed that cognitive function was positively related to intakes of zinc, fishes and shellfishes, beans & nuts, sugars and fats, and negatively related to intakes of plant calcium and eggs. These results indicate that intakes of specific nutrients or food groups are associated with the specific domains of cognitive function in elderly with AD.

• The Journal of the Acoustical Society of Korea
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• v.32 no.3
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• pp.262-268
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• 2013

The performances of speech compression schemes appeared to be dependent on the response profiles to compressed stimuli and the features of individual languages to some extent. Although these response profiles were critical in comparing various compression outcomes, the related data were limited in number for Korean monosyllabic words. From the previous study, data from PNT (Preserving No Trait) compression was selected as a base set for comparison. In this study, the outcomes from PPT (Preserving Pitch Trait) and PTT (Preserving Time Trait) were analyzed under the same condition. Then, the properties of these three widely used representative compression schemes were quantitatively compared in normal hearing adults (N=20) for controlled Korean quintet digit sets (0 through 9). Results showed that PPT compression scheme exhibited the best perceptual performances for the Korean quintet digit sets in the final outcomes (PPT>PTT>PNT). The compression ratios of 50% performances were estimated as about 20%, 42%, and 44% for PPT, PTT, and PNT, respectively. The data indicated the influences of the salient psychoacoustic features of the three representative compressions on perceiving Korean monosyllabic digit words. This controlled procedure with monosyllabic quintet sets can evaluate efficiency and effectiveness of other compression schemes and may also contribute to diagnosing auditory processing disorders and fitting special hearing aids with compression issues.