• 한국과학교육학회지
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• 제29권7호
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• pp.751-758
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• 2009

The purpose of this study was to investigate brain activation pattern and functional connectivity network during classification on the biological phenomena. Twenty six right-handed healthy science teachers volunteered to be in the present study. To investigate participants' brain activities during the tasks, 3.0T fMRI system with the block experimental-design was used to measure BOLD signals of their brain. According to the analyzed data, superior, middle and inferior frontal gyrus, superior and inferior parietal lobule, fusiform gyrus, lingual gyrus, and bilateral cerebellum were significantly activated during participants' carrying-out classification. The network model was consisting of six nodes (ROIs) and its fourteen connections. These results suggested the notion that the activation and connections of these regions mean that classification is consist of two sub-network systems (top-down and bottom-up related) and it functioning reciprocally. These results enable the examination of the scientific classification process from the cognitive neuroscience perspective, and may be used as basic materials for developing a teaching-learning program for scientific classification such as brain-based science education curriculum in the science classrooms.

• 생물정신의학
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• 제19권3호
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• pp.121-127
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• 2012

Objectives : The multimodal telepresence systems have been adopted in a variety of applications, such as telemedicine, space or underwater teleoperation and videoconference. Multimedia, one of the telepresence systems, has been used in various fields including entertainment, education and communication. The degree of subjective telepresence is defined as the probability that a person perceives to be physically in the remote place when he/she experiences a multisensory feedback from the multimedia. The current study aimed to explore the neural mechanism of telepresence related to multisensory feedback in patients with schizophrenia. Methods : Brain activity was measured using functional magnetic resonance imaging while fifteen healthy controls and fifteen patients with schizophrenia were experiencing filmed referential conversation at various distances (1 m, 5 m and 10 m). Correlations between the image contrast values and the telepresence scores were analyzed. Results : Subjective telepresence was not significantly different between the two groups. Some significant correlations of brain activities with the telepresence scores were found in the left postcentral gyrus, bilateral inferior frontal gyri, right fusiform gyrus, and left superior temporal sulcus. There were no main effects of group and distance. Conclusion : These results suggest that patients with schizophrenia experience telepresence as appropriately as healthy people do when exposed to multimedia. Therefore, patients with schizophrenia would have no difficulty in immersing themselves in multimedia which may be used in clinical training therapies.

• Investigative Magnetic Resonance Imaging
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• 제22권1호
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• pp.37-49
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• 2018

Purpose: The effect of global inhomogeneity on quantitative susceptibility mapping (QSM) was investigated. A technique referred to as Simultaneous Unwrapping Phase with Error Recovery from inhomogeneity (SUPER) is suggested as a preprocessing to QSM to remove global field inhomogeneity-induced phase by polynomial fitting. Materials and Methods: The effect of global inhomogeneity on QSM was investigated by numerical simulations. Three types of global inhomogeneity were added to the tissue susceptibility phase, and the root mean square error (RMSE) in the susceptibility map was evaluated. In-vivo QSM imaging with volunteers was carried out for 3.0T and 7.0T MRI systems to demonstrate the efficacy of the proposed method. Results: The SUPER technique removed harmonic and non-harmonic global phases. Previously only the harmonic phase was removed by the background phase removal method. The global phase contained a non-harmonic phase due to various experimental and physiological causes, which degraded a susceptibility map. The RMSE in the susceptibility map increased under the influence of global inhomogeneity; while the error was consistent, irrespective of the global inhomogeneity, if the inhomogeneity was corrected by the SUPER technique. In-vivo QSM imaging with volunteers at 3.0T and 7.0T MRI systems showed better definition in small vascular structures and reduced fluctuation and non-uniformity in the frontal lobes, where field inhomogeneity was more severe. Conclusion: Correcting global inhomogeneity using the SUPER technique is an effective way to obtain an accurate susceptibility map on QSM method. Since the susceptibility variations are small quantities in the brain tissue, correction of the inhomogeneity is an essential element for obtaining an accurate QSM.

• 인터넷정보학회논문지
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• 제4권6호
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• pp.57-67
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• 2003

최근 멀티미디어 처리 기술과 광학 기술의 발달과 더불어 얼굴 영상 정보를 이용한 응용 시스템에 대한 관심이 증대되고 있다. 기존의 얼굴 정보와 관련한 연구들은 대부분 정면 영상을 해석하여 사람을 식별하거나 영상의 표정을 분석하는데 초점을 두어왔으며 임의의 얼굴 영상의 방향성에 대한 연구는 부족한 실정이다. 특히, 한대의 카메라로 연속 촬영된 이미지들을 이용하는 기존의 방향성 검출 기법에서는 초기 영상이 정면 영상이어야 하는 제약점을 가진다. 본 논문에서는 얼굴의 특징 정보를 이용하여 임의의 얼굴 영상의 방항성을 검출하는 기법을 제안한다. 제안된 기법에서는 두 눈과 입술의 특징점을 기반으로 얼굴 사다리꼴을 정의하고, 얼굴 사다리꼴의 좌$.$우 면적을 비교한 통계 데이터를 이용하여 얼굴 영상의 좌.우 방향성을 계산하는 방향성 함수를 정의한다. 제안된 얼굴 영상의 검출 기법은 얼굴 영상의 방향성에 따라 얼굴 영상의 좌$.$우 여백을 안정적으로 설정하는 영상의 자동 배치 응용에 효과적으로 활용될 수 있다.

• 대한전자공학회논문지SP
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• 제41권6호
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• pp.155-164
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• 2004

최근 지능형 로봇에 대한 관심이 모아지고 있다. 지능형 로봇의 가장 큰 특징은 사용자를 추적, 인식하고 그 결과를 기반으로 상호활동적인 대응을 할 수 있다는 점이다. 얼굴인식이 다른 생채인식과의 비교에서 장점을 가질 수 있는 점은 비 강제성과 비 접촉성을 들 수 있다. 그러나 얼굴인식은 얼굴 취득단계부터 차원의 감소가 발생하고 인식하고자 하는 얼굴 및 주변 환경 변화가 매우 심하기 때문에 다른 생체인식에 비하여 인식률이 낮다. 얼굴인식의 성능을 저하시키는 요인들로는 조명변화, 포즈변화, 표정변화, 카메라와의 거리 등을 들 수 있다. 본 논문에서는 실제 환경에서 얼굴 인식 성능에 가장 많은 영향을 미치는 포즈변화에 대응하기 위하여 새로운 선형이동 능동형 카메라를 개발하여, 정면 얼굴에 근접한 영상을 취득하고 주성분 분석 및 Hidden Markov Model 알고리듬을 이용하여 인식률을 개선하고자 한다. 제한된 방법은 지능형 보안시스템 및 모바일 로봇에 적용하는 것을 목표로 개발 되었지만, 높은 정확도의 얼굴인식을 요구하는 응용분야에 널리 적용할 수가 있다.

• 제어로봇시스템학회논문지
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• 제21권1호
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• pp.59-64
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• 2015

In this paper, we found the usefulness of the deep belief network (DBN) in the fields of brain-computer interface (BCI), especially in relation to imagined speech. In recent years, the growth of interest in the BCI field has led to the development of a number of useful applications, such as robot control, game interfaces, exoskeleton limbs, and so on. However, while imagined speech, which could be used for communication or military purpose devices, is one of the most exciting BCI applications, there are some problems in implementing the system. In the previous paper, we already handled some of the issues of imagined speech when using the International Phonetic Alphabet (IPA), although it required complementation for multi class classification problems. In view of this point, this paper could provide a suitable solution for vowel classification for imagined speech. We used the DBN algorithm, which is known as a deep learning algorithm for multi-class vowel classification, and selected four vowel pronunciations:, /a/, /i/, /o/, /u/ from IPA. For the experiment, we obtained the required 32 channel raw electroencephalogram (EEG) data from three male subjects, and electrodes were placed on the scalp of the frontal lobe and both temporal lobes which are related to thinking and verbal function. Eigenvalues of the covariance matrix of the EEG data were used as the feature vector of each vowel. In the analysis, we provided the classification results of the back propagation artificial neural network (BP-ANN) for making a comparison with DBN. As a result, the classification results from the BP-ANN were 52.04%, and the DBN was 87.96%. This means the DBN showed 35.92% better classification results in multi class imagined speech classification. In addition, the DBN spent much less time in whole computation time. In conclusion, the DBN algorithm is efficient in BCI system implementation.

• 한국정보통신학회논문지
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• 제10권5호
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• pp.897-904
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• 2006

리오그랑디주에서 바이아주 남부까지 약 300 km에 이르는 길고 좁은 브라질 북동부 지역에서는 남동무역풍의 교란, 전선의 침투, 해륙풍 순환 그리고 지형과 수증기 플럭스에 기인하는 국지 대류와 같은 다양한 강수 시스템이 나타난다. 연간 총강수량은 내륙에서는 600 mm, 해안지역에서는 3000 mm의 분포를 보이고 있다. 지역 기후 평균에 5-12배의 강수량이 2004년 1월에 알라고아스주 여러 지역에서 기록되었다. 46,000명의 수재민이 발생했고, 10,000,000 US$의 재산 피해였다. 이 폭우는 $21^{\circ}W,\;12^{\circ}S$에서 형성된 UTCV가 1월 내내 브라질 북동부 지역에 머물면서 영향을 미쳤기 때문이라는 것을 GOES 적외선 영상 분석으로 알 수 있었다.

• 한국지능시스템학회논문지
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• 제19권1호
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• pp.122-127
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• 2009

본 논문에서는 피험자가 A, B, C, D 글자를 말하는 상상을 할 때 사고중추에서와 Broca's area 에서 EEG 신호를 측정하였으며 이 신호를 Event-Related Spectral Perturbation (ERSP), Inter-Trial Coherence (ITC) 그리고 Event Related Potential (ERP) 방법을 통해 분석하여 보았다. 그 결과 F7, FT7 영역의 뇌파에서 각 문자를 보여주는 자극 제시 후 0$\sim$300ms 동안의 1$\sim$13Hz에서 높은 coherence를 보였으며, P300 이 뚜렷하게 나타나는 것을 확인할 수 있었다. 하지만 ERP를 통해 분석해본 결과 각 글자에 대한 차이를 구분하고자 하였던 처음 연구의 동기와 달리 각 글자를 말할 때 ERP가 약간의 차이를 보이기는 하였으나 각 문자에 대한 차이라거나 이 차이를 통해 문자를 구별할 수 있다고 하기는 어려웠다. 하지만 본 논문에서는 이 실험결과를 통해 기존에 운동관련 뇌 영역에 국한되어 있던 BCI 연구의 한계를 극복하고 보다 다양한 서비스를 제공할 수 있는 응용 시스템을 제안하였다.

• 수면정신생리
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• 제5권2호
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• pp.119-133
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• 1998

Attentional processes facilitate cognitive and behavioral performance in several ways. Attention serves to reduce the amount of information to receive. Attention enables humans to direct themselves to appropriate aspects of external environmental events and internal operations. Attention facilitates the selection of salient information and the allocation of cognitive processing appropriate to that information. Attention is not a unitary process that can be localized to a single neuroanatomical region. Before the cortical registration of sensory information, activation of important subcortical structures occurs, which is called as an orienting response. Once sensory information reaches the sensory cortex, a large number of perceptual processes occur, which provide various levels of perceptual resolution of the critical features of the stimuli. After this preattentional processing, information is integrated within higher cortical(heteromodal) systems in inferior parietal and temporal lobes. At this stage, the processing characteristics can be modified, and the biases of the system have a direct impact on attentional selection. Information flow has been traced through sensory analysis to a processing stage that enables the new information to be focused and modified in relation to preexisting biases. The limbic and paralimbic system play significant roles in modulating attentional response. It is labeled with affective salience and is integrated according to ongoing pressures from the motivational drive system of the hypothalamus. The salience of information greatly influences the allocation of attention. The frontal lobe operate response selection system with a reciprocal interaction with both the attention system of the parietal lobe and the limbic system. In this attentional process, the search with the spatial field is organized and a sequence of attentional responses is generated. Affective, motivational and appectitive impulses from limbic system and hypothalamus trigger response intention, preparation, planning, initiation and control of frontal lobe on this process. The reticular system, which produces ascending activation, catalyzes the overall system and increases attentional capacity. Also additional energetic pressures are created by the hypothalamus. As psychophysiological measurement, skin conductance, pupil diameter, muscle tension, heart rate, alpha wave of EEG can be used. Event related potentials also provide physiological evidence of attention during information process. NI component appears to be an electrophysiological index of selective attention. P3 response is developed during the attention related to stimulus discrimination, evaluation and response.

• 한국임상수의학회지
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• 제36권1호
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• pp.53-61
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• 2019

Total hip arthroplasty (THA) is a successful surgical treatment for both patients with chronical lameness and dogs who are nonresponsive to medical treatments, providing excellent joint function for returning dogs to the normal gait in 80% to 98% of hip dysplasia (HD) patients. The THA surgical implant system manufactured by BioMedtrix and Kyon are today widely accepted. When comparing the BioMedtrix biological fixation (BFX) system to the BioMedtrix cemented fixation (CFX) system, the many advantages of BFX, which include longer potential implant life, decreased risk of postoperative or later infection, and better implant stability, become evident. However, BFX implies a greater risk of femoral fracture during reaming and requires a more precise surgical technique to achieve good implant fit, given the press-fit nature of cementless THA. The purposes of this study are to both describe the mistakes and complications during stem implantation for beginner surgeons with both the BFX and the CFX systems and to document the initial result of 12 implantations in canine cadavers. Given the detailed evaluations of 3 specialists, who are Diplomate American College of Veterinary Surgeons (DACVS), only 3 of 11 stems were appropriately sized. Specifically, 6 stems were anteverted rather than being retroverted; further, although 7 stems were coaxial with the femoral long axis in the frontal plane, the other stems were in the varus at the frontal plane, with the proximal medial stem adjacent to the medial femoral cortex. Moderate angulation from the cranial to the caudal directions was found in 4 cases in the sagittal plane. Additionally, 1 case of femoral fissure and 1 case of perforated femoral cortex were reported. It is not easy for surgeons performing cementless THA for the first time to achieve a good result, even though they completed an educational course about it and given that catastrophic complications often occurred during early surgical clinical cases. Therefore, ex-vivo studies are sincerely required to get an expertise by rehearsing the preparation of the femoral envelop in isolated bones. Further studies should be conducted to achieve both highly accurate implant size and correct orientation during the preoperative planning. Additionally, surgeons' learning curve should be examined in future investigations.