• Korean Journal of Cognitive Science
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• v.19 no.2
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• pp.125-142
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• 2008

This study investigated the effects of space- and object-based attention on spatial and visual working memory, by measuring recognition of working memory on the spatial Stroop task including two modalities of attention resource. The similarity condition of stimulus arrangement between working memory task and spatial stroop task was manipulated in order to examine the effects of space-based attention on spatial rehearsal during working memory task, while Stroop rendition was manipulated in order to examine the effects of object-based attention on object rehearsal during working memory task. The results showed that in a condition that stimulus arrangement was highly similar for the spatial working memory task and the spatial Stroop task, recognition accuracy of the spatial working memory was high, but it was not significantly different with the Stroop conditions. In contrast, the recognition accuracy of visual working memory in the incongruent Stroop condition was lower than that in the congruent Stroop condition, but it was not significantly different with the similarity conditions (25% vs. 75%). The results indicated that selective attention has effects on working memory only when resource modality of working memory is the same as that of selective attention.

• Science of Emotion and Sensibility
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• v.14 no.3
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• pp.371-384
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• 2011

Three experiments were carried out to examine how LED lighting hues influence to the rating and recognition of affective stimuli. In Experiment 1 and 2, IAPS affective pictures were used and an affective rating(valence and arousal) task and a recognition memory task were conducted under red, green, blue, and white hue LED lightings in Experiment 1 and cyan, magenta, yellow, and white ones in Experiment 2, respectively. In Experiment 3, affective words were used and the same two tasks were conducted under red, green, blue, and white hue LED lightings. According to the results of affective rating tasks, when primary hues(RGB) were used, red LED lighting elicited an excitement at the arousal dimension and green LED lighting evoked pleasantness at the valence one. When secondary hues(CMY) were used, magenta and cyan showed the similar but weaker patterns of responses comparing to red and green. The results of recognition memory task showed that the responses to the picture stimuli presented at green and cyan hue lightings tended to be a bit faster comparing to the stimuli presented at the other conditions but the difference was insignificant. In Experiment 3, however, recognition memory responses to the affective words presented at green hue lighting were faster significantly. These results indicate that warm colors like red and magenta elicit unpleasantness or excitement while cool colors like green and cyan evoke pleasantness or relaxation, and the primary hues provoke more positive or negative affectivity than secondary ones do. Particularly, the result of recognition memory task in Experiment 3 suggests that green hue LED lighting might be advantageous at the memory performance of language stimuli rather than visual ones.

• Korean Journal of Cognitive Science
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• v.21 no.2
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• pp.359-386
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• 2010

In order to evaluate the domain-specific model and process-specific model of spatial and nonspatial working memory (WM), this study manipulated the memory load of the delayed response task and examined how the neural correlates of memory load effect was influenced by the stimulus domain (face and location) at the maintenance stage of WM using an event-related fMRI experiment. One or three face stimuli were presented as target stimuli and participants were asked to maintain the face itself (face WM) or the location of face stimuli (spatial WM). The results of recognition judgment accuracy showed no difference between face WM and spatial WM, and showed equivalent memory load effects of both WM. As a result of brian image analysis, memory load effect at maintenance stage showed that inferior, middle, and superior PFC were recruited by both face WM and spatial WM, and showed that VLPFC was the commonly activated area by both WM, supporting functional specialization of PFC by process components of WM. This study provides evidence for process-specific model in which maintenance of WM is associated with VLPFC.

• Korean Journal of Cognitive Science
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• v.16 no.1
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• pp.1-15
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• 2005

Since human visual system has limited capacity for visual information processing, it should select goal-relevant information for further processing. There have been several studies that emphasized the possible involvement of memory in spatial shift of selective attention (Chun & Jiang, 1998, 1999; Klein, 1988; Klein & MacInnes, 1999). However, other studies suggested the inferiority of human visual memory in change detection(Rensink, O'Regan, & Clark, 1997; Simons & Levin, 1997) and in visual search(Hotowitz & Wolfe, 1998). The present study examined the involvement of memory in visual search; whether memory for the previously searched items guides selective attentional shift or not. We investigated how search works by comparing visual search performances in three different conditions; full exposure condition, partial exposure condition, and partial-to-full exposure condition. Revisiting searched items was allowed only in full exposure condition and not in either partial or partial-to-full exposure condition. The results showed that the efficiencies of attentional shift were nearly identical for all conditions. This finding implies that even in full exposure condition the participants scarcely re-examined the previously searched items. The results suggest that instant memory can be formed and used in visual search process. These results disagree with the earlier studies claiming thar visual search has no memory. We discussed the problems of the previous research paradigms and suggested some alternative accounts.

• Composites Research
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• v.31 no.6
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• pp.347-354
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• 2018

Shape memory polymer composites have been studied for deployable antennas in space because they have advantages of lightweight, large deformability, good processability, and low cost. In this research, shape memory polymer composites (SMPCs) were manufactured using carbon nanotubes (CNTs) as reinforcements and were used to fabricate SMPC antenna. The SMPCs were prepared by dispersing CNTs in the polymer matrix. Various dispersion methods were investigated to determine the most suitable one, focusing on the mechanical properties of SMPCs including their fracture behavior. The shape memory properties of SMPCs were measured and finally, the deployment behavior of the SMPC antenna was analyzed.

• Science of Emotion and Sensibility
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• v.11 no.3
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• pp.397-418
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• 2008

This research investigated differences of perception ratio and processes of memory reconstruction. To examine the differences in perception for positive or negative events related to individual subjective well-level, 199 participants were asked to report the perceived ratio of positive versus negative events for the provided event list. Also, recall differences of positive versus negative events were examined in relation to individual differences in happiness. Results partially supported the hypothesis that happy people perceive more positive stimulus in a given situation than less happy people. Happy people also showed more positive percentage in recalled events than actual ratio while unhappy people reported less positive recall percentage than actual ratio. These findings indicate existence of cognitive process that enhances positive or negative memory related to subjective well-being. Significant correlation between perceived ratio and recalled ratio further supports this proposition. Finally, theoretical implications of the present research and suggestions for future research were discussed.

• Sleep Medicine and Psychophysiology
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• v.4 no.1
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• pp.29-38
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• 1997

Dementia is defined as a syndrome which is characterized by various impairments in cognitive functions, especially memory function. Most of the diagnostic criteria for dementia include memory impairment as on essential feature. Memory decline can be present as a consequence of the aging process. But it does not cause significant distress or impairment in social and occupational functionings while dementiadoes. Depression may also be associated with memory impairment. However, unlike dementia, depression dose not cause decrease in delayed verbal learning and recognition memory. In dementia, different features of memory impairment may be present depending on the involved area. Memory impairment in cortical dementia is affected by the disturbance of encoding of information and memory consolidation, while memory imparnene in subcortical denentiy is affected by the disturbance of retrieval in subcortical dementia.

• Proceedings of the Korean Society for Cognitive Science Conference
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• 2000.05a
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• pp.55-60
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• 2000

연속재인과제에서 자극을 즉각적으로 반복 제시하거나 지연 반복 제시할 경우 사건관련전위에 차이가 나타나는지, 만약 차이가 관찰되면 자극 제시 후 어느 시점에서 차이가 두드러지게 나타나는지를 조사하였다. 실험 결과 즉각적 재인이 지연 재인에 비해 더 높은 반응정확율과 더 빠른 반응시간을 보였고 사건관련전위에서는 P300의 진폭이 더 컸고 잠재시간도 더 빨랐다. 그리고 지연재인에서 관찰되는 N400이 즉각적 재인에서는 나타나지 않았다. 지연재인에 비해 즉각적 재인에서 P300의 진폭이 더 크고 잠재시간이 더 빠르게 나타난 것은 P300이 template matching을 통한 정보처리 과정을 반영해 준다는 주장을 지지해 준다. 즉 즉각적 재인에서는 지연 재인에 비해 template matching이 훨씬 더 정확하고 빨리 일어나며 이 결과 P300의 진폭이 커지고 잠재시간이 더 빨라진 것으로 이해된다. 즉각적 재인에서는 방금 제시된 자극(시간 간격은 2초)을 재인하기 때문에 기억의 탐색 과정이 요구되지 않는 반면 5개의 간섭 단어 후에 반복 제시되는 단어를 재인하는 지연 재인에서는 단어에 대한 탐색 과정이 필요하며, 이에 따라 N400이 초래된 것으로 여겨진다. 이 결과는 N400이 기억 탐색 과정을 반영한다는 주장을 지지해 준다. 사건관련 전위에서 즉각적 재인과 지연 재인의 차이는 자극 제시 300ms에서 450ms사이에 가장 두드러지게 나타났다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.4
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• pp.44-52
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• 2003

Shape memory alloys (SMA) are often used in smart structures as active components. Their ability to provide large recovery forces and displacements has been useful in many applications, including devices for artificial muscles, active structural acoustic control, and shape control. Based on the 3-dimensional SMA constitutive equation in this paper, the radial displacement control of externally pressurized circular and semicircular composite cylinders under external pressure with a thin SMA layer bonded on its inner surface or inserted between composite layers in investigated using 3-dimensional finite element analysis. Upon actuation through resistive heating, SMAs start to transform from martensitic into austenitic state, simultaneously recover the prestrain, and thus cause the composite cylinders to go back to their original shapes of the cylinder cross-sections.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.453-456
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• 2009

Impact resistance of shape memory alloy hybrid composite(SMAHC) plates were experimentally investigated. Shape memory alloy(SMA) have large failure strain and failure stress and can absorb large strain energies through phase transformation. SMA wires were embedded in composite plates to improve their weak impact resistance. Tensile tests of SMA wires were performed at various temperature to investigate their thermo-mechanical properties. Low-Velocity impact tests of several types of composite plates with SMA/Al/Fe were performed. Embedding SMA wires was most effective to improve impact resistance of composite plates. The effects of SMA position on impact resistance were also investigated.