• Journal of Digital Convergence
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• v.14 no.6
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• pp.535-546
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• 2016

This study examined the relation among orthographic knowledge, phonological awareness, and visual word decoding and encoding abilities. Children aged 5 to 8 years took letter knowledge test, phoneme-grapheme correspondence test, orthographic representation test(regular word and irregular word representation), phonological awareness test(word, syllable and phoneme awareness), word decoding test(regular word and irregular word reading) and word encoding test(regular word and irregular word dictation). The performances of all tasks were significantly different among groups, and there were positive correlations among the tasks. In the word decoding and encoding tests, the variables with the most predictive power were the letter knowledge ability and the orthographic representation ability. It was found that orthographic knowledge more influenced visual word decoding and encoding skills than phonological awareness at these ages.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.49-50
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• 2015

본 논문에서는 이미지를 시각적 단어로 표현하여 분석하는 기법인 bag-of-visual words (BoW) 모델을 기반으로 latent dirichlet allocation (LDA) 모델을 결합하여 시각적 단어의 구조를 파악하여 이미지를 분류할 수 있는 모델을 제안한다. 우선 이미지를 시각적 단어로 기존의 방법보다 정확하게 표현하기 위해서 희소 부호화(sparse coding) 기법을 적용한다. 기존의 BoW 모델은 하나의 이미지 패치를 하나의 단어로 표현하였지만, 희소 부호화 기법을 통해 하나의 이미지 패치를 여러 개의 단어로 표현할 수 있다. 제안하는 모델을 이용하여 이미지를 분류하기 위해서 분류 성능 측정에 많이 쓰이는 multi-class SVM 기법을 이용한다. UIUC 스포츠 데이터를 이용한 성능 측정을 통해 제안한 기법의 클래스 분류 성능을 검증하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.06a
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• pp.35-36
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• 2016

본 논문에서는 기존 Bag-of-Visual words (BoW) 접근법에서 반영하지 못한 이미지의 공간 정보를 활용하기 위해서 Spatial Pyramid Matching (SPM) 기법을 Latent Dirichlet Allocation (LDA) 모델에 결합하여 이미지를 분류하는 모델을 제안한다. BoW 접근법은 이미지 패치를 시각적 단어로 변환하여 시각적 단어의 분포로 이미지를 표현하는 기법이며, 기존의 방식이 이미지 패치의 위치정보를 활용하지 못하는 점을 극복하기 위하여 SPM 기법을 도입하는 연구가 진행되어 왔다. 또한 이미지 패치를 정확하게 표현하기 위해서 벡터 양자화 대신 희소 부호화 기법을 이용하여 이미지 패치를 시각적 단어로 변환하였다. 제안하는 모델은 BoW 접근법을 기반으로 위치정보를 활용하는 SPM 을 LDA 모델에 적용하여 시각적 단어의 토픽을 추론함과 동시에 multi-class SVM 분류기를 이용하여 이미지를 분류한다. UIUC 스포츠 데이터를 이용하여 제안하는 모델의 분류 성능을 검증하였다.

• Korean Journal of Cognitive Science
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• v.13 no.1
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• pp.23-40
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• 2002

This study is to examine brain regions that are involved in picture encoding in normal adults using fMRI methods. In Scan 1, the picture encoding was studied during a semantic categorization task in comparison with word. In Scan 2 task type effects were studied both during a picture naming task and during a semantic categorization task with pictures. Subjects were asked to make decision either by pressing a mouse button (Scan 1) or by responding subvocally (naming or saying yes/no) (Scan 2). Regardless of stimulus type, left prefrontal, bilateral occipital, and parietal activations were observed during semantic processing in comparison with fixation baseline. Processing of word stimulus relative to picture resulted in activations in prefrontal and parieto-temporal regions in the left side while that of picture stimulus relative to word resultd in activations in bilateral extrastriatal visual cortices and parahippocampal regions. In spite of the same task demands, stimulus-specific information processings were involved and mediated by different neural substrates; the word encoding was associated with more semantic/lexical processings than pictures and the picture processing associated with more perceptual and novelty related information processings than word. Activations of dorsal part of inferior prefrontal region, i.e., Broca's areas were found both during the picture naming and during the semantic tasks subvocally performed Especially, during the picture naming task, greater occipital activations were found bilaterally relative to the semantic categorization task. indicating a possibility that greater and higher visual processing was involved in retrieving the name referred by picture stimuli.

• Korean Journal of Cognitive Science
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• v.26 no.1
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• pp.1-26
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• 2015

The purpose of this study was to examine whether the phonological information or the orthographic information plays a major role in visual word recognition. To do so, we used a non-word lexical decision task(LDT) in Experiment 1 and masked priming tasks in Experiement 2 and 3. The results of Experiment 1 showed that reaction times and the error rates were affected by the orthographic characteristics of the non-word stimuli such that orthographically similar non-words condition showed prolonged reaction times and higher error rates than control condition. In Experiment 2 and Experiment 3, the participants performed masked priming lexical decision tasks in two SOA conditions(60ms, 150ms). The results of the both experiments showed that the orthographically identical first syllable priming facilitated lexical decision of the target words while both of the pseudo-homophone priming and the phonologically identical first syllable priming did not. The dual route hypothesis(Coltheart et al, 2001), assuming that orthographic information rather than phonological information is the major source for the visual word recognition processes, fits well with the results of the current study.

• Korean Journal of Cognitive Science
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• v.11 no.3_4
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• pp.13-22
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• 2000

The present study examined the role of spatial attention in implicit memory for words when the word identity processing was not required. Spatial attention to the identity-irrelevant perceptual features of the words was manipulated by using a visual search task (Experiment 1) or a focused attention task (Experiment 2). In two e experiments. a significant priming effect was not found for the target words as well as for the distractor words. Implicit memory for words was not affected by spatial attention on the perceptual properties of the words. indicating that the word identity processing is required to produce priming.

• Korean Journal of Cognitive Science
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• v.25 no.1
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• pp.1-24
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• 2014

Growing boy of studies focus on the letter transposition effect since it gives the information on how letters are coded and what variables are involved in the processes of word recognition. This review investigated various models on letter transposition effect. While most proposed models rely mainly on the bottom-up processes, evidences from various studies suggested the necessity of the top-down variables based on the cognitive processing mechanism. Especially, empirical evidences suggested that Hangul model should include a position specific processing mechanism based on onset, vowel, and coda of the Korean character.

• The Korean Journal of Nuclear Medicine
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• v.34 no.1
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• pp.10-21
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• 2000

Purpose: Episodic memory is described as an 'autobiographical' memory responsible for storing a record of the events in our lives. We performed functional brain activation study using ${H_2}^{15}O$ PET to reveal the neural basis of the encoding and the retrieval of episodic memory in human normal volunteers. Materials and Methods: Four repeated ${H_2}^{15}O$ PET scans with two reference and two activation tasks were performed on 6 normal volunteers to activate brain areas engaged in encoding and retrieval with verbal materials. Images from the same subject were spatially registered and normalized using linear and nonlinear transformation. Using the means and variances for every condition which were adjusted with analysis of covariance, t-statistic analysis were performed voxel-wise. Results: Encoding of episodic memory activated the opercular and triangular parts of left inferior frontal gyrus, right prefrontal cortex, medial frontal area, cingulate gyrus, posterior middle and inferior temporal gyri, and cerebellum, and both primary visual and visual association areas. Retrieval of episodic memory activated the triangular part of left inferior frontal gyrus and inferior temporal gyrus, right prefrontal cortex and medial temporal area, and both cerebellum and primary visual and visual association areas. The activations in the opercular part of left inferior frontal gyrus and the right prefrontal cortex meant the essential role of these areas in the encoding and retrieval of episodic memory. Conclusion: We could localize the neural basis of the encoding and retrieval of episodic memory using ${H_2}^{15}O$ PET, which was partly consistent with the hypothesis of hemispheric encoding/retrieval asymmetry.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.8 no.1
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• pp.101-112
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• 1997

The purpose of this study was to examine usefulness of KEDI-Individual Basic Learning Skills Test as a diagnostic tool of learning disorders(LD). Learning disorder group consisted of two subgroups, verbal learning disorder group(VLD, n＝34) and nonverbal learning disorder group(NVLD, n＝14). Comparison group consisted of Dysthymia Disorder subgroup(n＝11) and Normal subgroup(n＝20). Performance of intelligence test and achievement test was examined in all 4 subgroups. In KEDI-WISC, VLD subgroup revealed primary problems in vocabulary, information and verbal-auditory attention test. NVLD group revealed primary problems in almost all performance tests such as visual acuity, psycho-motor coordination speed and visual-spatial organizations ability subtest. In KEDI-Individual Basic Learning Test, VLD group revealed primary problems in phonological coding process, word recognition and mathematics. For successful classification of LD children, the importance of achievement test and intelligence test was discussed by discriminant analysis and factor analysis. The results indicate that KEDI-Individual Basic Learning Skills is of considerable usefulness in diagnosing LD, but must be used in subtests, and additional tests must be conducted for thorough exploration of LD.