• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권11호
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• pp.4502-4518
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• 2015

Fisher linear discriminant analysis (LDA) is one of the most popular projection techniques for feature extraction and has been widely applied in face recognition. However, it cannot be used when encountering the single sample per person problem (SSPP) because the intra-class variations cannot be evaluated. In this paper, we propose a novel method called local similarity based linear discriminant analysis (LS_LDA) to solve this problem. Motivated by the "divide-conquer" strategy, we first divide the face into local blocks, and classify each local block, and then integrate all the classification results to make final decision. To make LDA feasible for SSPP problem, we further divide each block into overlapped patches and assume that these patches are from the same class. To improve the robustness of LS_LDA to outliers, we further propose local similarity based median discriminant analysis (LS_MDA), which uses class median vector to estimate the class population mean in LDA modeling. Experimental results on three popular databases show that our methods not only generalize well SSPP problem but also have strong robustness to expression, illumination, occlusion and time variation.

• 디지털융복합연구
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• 제20권2호
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• pp.289-297
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• 2022

이 연구는 2020학년도 전 학기 비대면 교육 이후 온라인수업을 경험한 치과대학생의 전반적인 인식을 조사하는데 목적이 있다. 연구방법은 A대학교 치과대학생 161명을 대상으로 온라인 설문조사를 실시하였으며, 설문문항은 비대면 수업 만족도, 학습시스템, 교수요인, 평가방법과 온라인수업 요구조사이다. 분석방법은 빈도분석, 상관관계분석, 다중회귀분석을 사용하였다. 설문 분석 결과 치과대학생이 경험한 비대면 교육만족도는 4.2이상이며, 세부항목별로 보면, 출결처리 방식의 적절성, 녹화영상 강의에 대한 만족, 수업성적 평가 방식에 만족 순으로 나타났다. 비대면 교육만족도에 영향을 미치는 요인으로는 학습시스템과 평가방법이 통계적으로 유의하였다. 이 연구는 A대학의 비대면 교육 운영 상황만을 연구한 것으로 모든 대학에 일반화 할 수 없지만, 대면 및 비대면 수업의 양립을 위한 교육과정 설계 및 지원 방안을 마련하기 위한 기초자료로 활용할 수 있을 것이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권6호
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• pp.2098-2114
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• 2021

Light intensity variation is one of the key factors which affect the accuracy of vehicle face re-identification, so in order to improve the robustness of vehicle face features to light intensity variation, a Nonnegative Matrix Factorization model with the constraint of image acquisition time difference is proposed. First, the original features vectors of all pairs of positive samples which are used for training are placed in two original feature matrices respectively, where the same columns of the two matrices represent the same vehicle; Then, the new features obtained after decomposition are divided into stable and variable features proportionally, where the constraints of intra-class similarity and inter-class difference are imposed on the stable feature, and the constraint of image acquisition time difference is imposed on the variable feature; At last, vehicle face matching is achieved through calculating the cosine distance of stable features. Experimental results show that the average False Reject Rate and the average False Accept Rate of the proposed algorithm can be reduced to 0.14 and 0.11 respectively on five different datasets, and even sometimes under the large difference of light intensities, the vehicle face image can be still recognized accurately, which verifies that the extracted features have good robustness to light variation.

• International Journal of Contents
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• 제10권2호
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• pp.18-27
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• 2014

This study examines underlying factors that influence undergraduate students' willingness to enhance communication with their instructor by comparing the frequency of e-mail and face-to-face interaction between students and instructors. Data was collected through a survey of 322 undergraduate journalism students at a large Midwestern university. The findings showed that the more passive students were in expressing their opinion during the class, the less likely they were to send e-mails to their instructor (Coef. = -0.180, p < .01) or to communicate with their instructor face-to-face (Coef. = -0.262, p < .01). The findings also showed that the more students described their personality as "shy," the less likely they were to e-mail their instructor (Coef. = -0.157, p < .05) or communicate with their instructor face-to-face (Coef. = -0.210, p < .01). It is noteworthy that the degrees of both passivity and shyness had a more negative effect on the probability of face-to-face interaction than they did on email interaction. In summary, email usage follows similar broader patterns of social interaction, rather than introducing a different trend in communication. This finding implies that the importance of e-mail should not be exaggerated as a communication tool for reticent students.

• 대한임베디드공학회논문지
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• 제8권3호
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• pp.137-143
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• 2013

This paper describes an implementation of face detection technology for a real-time application on the Android platform. Java class of Face-Detection for detection of human face is provided by the Android API. However, this function is not suitable to apply for the real-time applications due to inadequate detection speed and accuracy. In this paper, the AdaBoost based classification method which utilizes Local Binary Pattern (LBP) histogram is employed for face detection. The face detection module has been developed by C/C++ language for high-speed image processing, and this module is included to the Android platform using the Java Native Interface (JNI). The experiments were carried out in the Java-based environment and JNI-based environment. The experimental results have shown that the performance of JNI-based is faster than Java-based method and our system is well enough to apply for real-time applications.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권7호
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• pp.2667-2682
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• 2015

Due to the wide application of face recognition (FR) in information security, surveillance, access control and others, it has received significantly increased attention from both the academic and industrial communities during the past several decades. However, partial face occlusion is one of the most challenging problems in face recognition issue. In this paper, a novel method based on linear regression-based classification (LRC) algorithm is proposed to address this problem. After all images are downsampled and divided into several blocks, we exploit the evaluator of each block to determine the clear blocks of the test face image by using linear regression technique. Then, the remained uncontaminated blocks are utilized to partial occluded face recognition issue. Furthermore, an improved Distance-based Evidence Fusion approach is proposed to decide in favor of the class with average value of corresponding minimum distance. Since this occlusion removing process uses a simple linear regression approach, the completely computational cost approximately equals to LRC and much lower than sparse representation-based classification (SRC) and extended-SRC (eSRC). Based on the experimental results on both AR face database and extended Yale B face database, it demonstrates the effectiveness of the proposed method on issue of partial occluded face recognition and the performance is satisfactory. Through the comparison with the conventional methods (eigenface+NN, fisherfaces+NN) and the state-of-the-art methods (LRC, SRC and eSRC), the proposed method shows better performance and robustness.

• Restorative Dentistry and Endodontics
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• 제42권1호
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• pp.48-53
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• 2017

Objectives: The aim of this study was to investigate the ability of the fluorescence-aided caries excavation (FACE) device to detect residual caries by comparing conventional methods in vivo. Materials and Methods: A total of 301 females and 202 males with carious teeth participated in this study. The cavity preparations were done by grade 4 (Group 1, 154 teeth), grade 5 (Group 2, 176 teeth), and postgraduate (Group 3, 173 teeth) students. After caries excavation using a handpiece and hand instruments, the presence of residual caries was evaluated by 2 investigators who were previously calibrated for visual-tactile assessment with and without magnifying glasses and trained in the use of a FACE device. The tooth number, cavity type, and presence or absence of residual caries were recorded. The data were analyzed using the Chi-square test, the Fisher's Exact test, or the McNemar test as appropriate. Kappa statistics was used for calibration. In all tests, the level of significance was set at p = 0.05. Results: Almost half of the cavities prepared were Class II (Class I, 20.9%; Class II, 48.9%; Class III, 20.1%; Class IV, 3.4%; Class V, 6.8%). Higher numbers of cavities left with caries were observed in Groups 1 and 2 than in Group 3 for all examination methods. Significant differences were found between visual inspection with or without magnifying glasses and inspection with a FACE device for all groups (p < 0.001). More residual caries were detected through inspection with a FACE device (46.5%) than through either visual inspection (31.8%) or inspection with a magnifying glass (37.6%). Conclusions: Within the limitations of this study, the FACE device may be an effective method for the detection of residual caries.

• 산업기술연구
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• 제28권B호
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• pp.143-148
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• 2008

A real-time face detection is to find human faces robustly under the cluttered background free from the effect of occlusion by other objects or various lightening conditions. We propose a face detection system for real-time applications using wavelet decomposition method based on Gabor features. Firstly, skin candidate regions are extracted from the given image by skin color filtering and projection method. Then Gabor-feature based template matching is performed to choose face cadidate from the skin candidate regions. The chosen face candidate region is transformed into 2-level wavelet decomposition images, from which feature vectors are extracted for classification. Based on the extracted feature vectors, the face candidate region is finally classified into either face or nonface class by the Levenberg-Marguardt back-propagation neural network.

• 한국치위생학회지
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• 제21권6호
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• pp.805-812
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• 2021

Objectives: To investigate the perceived quality of classes, academic emotions, and learning achievement levels associated with the non-face-to-face classes of health science students, and to analyze the factors related to class satisfaction. Methods: Using a questionnaire, 238 health science students were surveyed regarding the quality of classes, academic emotions, and learning achievement levels. Factors related to calss satisfaction were analyzed using stepwise multiple regression. Results: Lecture types that the students were most satisfied with were 'video lectures using PPT' and 'recorded lectures provided by LMS', while 'real-time video lectures' were scored the lowest (p=0.005). Factors affecting non-face-to-face class satisfaction were perceived achievement (β=0.425, p<0.001), learning content (β=0.265, p<0.001), learning emotion (β=0.171, p<0.001), and learning environment (β=0.137, p=0.012). The adjusted explanatory power for this model was 63.9%. Conclusions: To increase the satisfaction of health science students with non-face-to-face classes, it is necessary to prepare an institutional foundation and to develop an educational program that can increase perceived achievement.

• 대한소아치과학회지
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• 제28권4호
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• pp.643-648
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• 2001

III급 부정교합은 전치가 수평적으로 반대로 물리는 양상 때문에 치과의사뿐만 아니라 일반인에 의해서도 쉽게 발견되므로 비교적 조기에 치과를 찾는 빈도가 높다. 이러한 III급 부정교합 치료 시에 치과의사들이 사용할 수 있는 방법은 여러 가지가 있을 수 있으며 그 중 정형적 Face mask는 III급 부정교합에 기여하는 모든 요소 즉, 상악골 후퇴, 하악전돌, 낮은 전방하안면고경에 전반적으로 영향을 미치기 때문에 가장 폭넓게 적용가능하고 가장 짧은 기간에 극적인 결과를 나타내기 때문에 대부분의 발육중인 III급 증례에 적용될 수 있다. 이에 본원에 내원한 III급 부정교합 환아에서 Face mask를 적응함으로써 다음과 같은 결과를 얻었다. 1. 전치부 반대 교합이 상악골의 전방이동 하악골의 후하방 회전에 의해 해소되었다. 2. 경조직, 연조직에서 안모의 개선이 나타났다.