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실시간 표면 정합 기반 전극배치 유도 시스템
No full textElectroencephalography (EEG) has been frequently used to measure the neural activity in brain researches. In EEG based longitudinal study, repeatability of electrode positioning is important for the consistent EEG assessment over a long period of time. Conventional methods including the international 10-20 or its expanded systems have been adopted to provide a standardized electrode positioning. The methods use four principal anatomical landmarks including nasion, inion, left and right pre-auricular points as fiducial locations for electrode placement. However, the landmarks are manually identified via visual inspection or palpation, involving variations in locations of affixed electrodes and in turn alterations in measured EEG signals. In this study, we proposed an electrode guidance navigation based on markerless augmented reality visualization, which aims to enable the precise electrode placement in a cost-effective way. The presented system uses a RGB-D camera for scanning and registration of facial surface or electrodes and thereby visualizes reference and current electrode position in real time. The experimental results from the phantom study confirmed that the positioning precision of the proposed system was improved in comparison with that of the conventional 10-20 positioning system. We believe that the presented system would be a possible alternative to the conventional systems for precise electrode placement in longitudinal EEG studies. ⓒ 2017 DGISTⅠ. INTRODUCTION 1 --
1.1 Introduction of augmented reality-based surgical navigation 1 --
1.2 Electroencephalography and electrode positioning system 2 --
1.3 Conventional methods 3 --
1.4 Proposed method 6 --
Ⅱ. METHODS 8 --
2.1 Configuration of the system 8 --
2.1.1 System overview 8 --
2.1.2 Development environment 9 --
2.2 Procedure for electrode guidance 10 --
2.2.1 Preparation step 10 --
2.2.2 Navigation step 11 --
2.3 Real-time surface registration 13 --
2.3.1 Iterative closest point algorithm 13 --
2.3.2 Image-to-patient registration 16 --
2.3.3 Adaptive initial alignment 18 --
2.3.4 Parallel process for real-time visualization 18 --
2.4 Experiment methods 19 --
Ⅲ. RESULTS 23 --
3.1 Evaluation of electrode positioning accuracy 23 --
3.2 Evaluation of real-time surface registration performance 26 --
Ⅳ. DISCUSSION AND CONCLUSION 28 --
Ⅴ. REFERENCE 30 --뇌전도(Electroencephalography, EEG)는 대표적인 비침습적 뇌 활동 측정 방법으로, 전기적 신호를 바탕으로 뇌 활동을 측정한다. EEG를 사용하는 중•장기적 연구에서는 반복 측정의 신뢰성(Test-retest reliability)을 보장하기 위해서 재현성 있는 전극 배치가 중요하다. 10-20 시스템은 재현성 있는 전극 배치를 위해 개발된 대표적인 전극 배치 시스템이다. 기존의 10-20 시스템은 비근점, 뒤통수점, 좌-우 이개전방점과 같은 인체의 해부학적 특징점을 바탕으로 전극을 배치하게 된다. 하지만 해부학적 특징점은 환자에 따라 변동이 크고 불분명하며, 시각과 촉각에 의존하여 특징점을 인식하고 위치를 측정해야 하므로 오차의 발생 가능성이 크다. 상기 문제점을 해결하기 위해서 본 연구에서는 마커리스 증강현실 기술을 활용하여 보다 정확한 전극배치가 가능한 시스템을 제안하였다. 제안하는 시스템은 RGB-D 카메라만으로 구성되어 비용 효율이 높고, 증강현실의 영상 정보를 바탕으로 간편하고 정확한 전극의 배치를 돕는다. EEG 전극배치를 위한 영상정보를 제공하기 위해서, RGB-D 카메라의 실시간 스캔 정보와 저장된 기준 정보간의 실시간 표면을 진행한다. 실시간 표면 정합 결과, 얼굴 표면 정보를 기준으로 저장된 기준 전극위치와 실시간 전극위치가 함께 시각화 되고, 영상 정보를 바탕으로 실시간 전극 위치를 기준 전극 위치에 중첩하여 위치시킴으로써 재현성 있는 전극 배치가 가능하다. 제안하는 시스템은 전극배치 과정에서 별도의 해부학적 특징점 인식이 필요하지 않으므로 간편하고 정확한 전극배치를 보장할 수 있다. 제안하는 시스템의 평가를 위하여, 기존의 10-20 시스템과 전극 배치오차 비교 실험을 진행하였다. 해부학적 특징점이 표현된 두상모형을 사용하여 실험을 진행하였으며, 제안하는 시스템과 기존의 10-20 시스템을 사용하여 각각 20회 전극 배치오차를 측정하였다. 실험결과, 제안하는 시스템의 평균 배치오차가 기존의 시스템에 비해 크게 감소함을 확인하였다. 따라서, 제안하는 시스템은 EEG를 사용하는 중•장기적 연구에서 간편하고 재현성 있는 전극배치를 제공할 것으로 기대한다. ⓒ 2017 DGISTMasterdCollectio
Augmented reality-based electrode guidance system for reliable electroencephalography
Get PDFAbstract Background In longitudinal electroencephalography (EEG) studies, repeatable electrode positioning is essential for reliable EEG assessment. Conventional methods use anatomical landmarks as fiducial locations for the electrode placement. Since the landmarks are manually identified, the EEG assessment is inevitably unreliable because of individual variations among the subjects and the examiners. To overcome this unreliability, an augmented reality (AR) visualization-based electrode guidance system was proposed. Methods The proposed electrode guidance system is based on AR visualization to replace the manual electrode positioning. After scanning and registration of the facial surface of a subject by an RGB-D camera, the AR of the initial electrode positions as reference positions is overlapped with the current electrode positions in real time. Thus, it can guide the position of the subsequently placed electrodes with high repeatability. Results The experimental results with the phantom show that the repeatability of the electrode positioning was improved compared to that of the conventional 10–20 positioning system. Conclusion The proposed AR guidance system improves the electrode positioning performance with a cost-effective system, which uses only RGB-D camera. This system can be used as an alternative to the international 10–20 system
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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