• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.321-344
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• 2017

Smart homes are the new generation of homes where pervasive computing is employed to make the lives of the residents more convenient. Human activity recognition (HAR) is a fundamental task in these environments. Since critical decisions will be made based on HAR results, accurate recognition of human activities with low uncertainty is of crucial importance. In this paper, a novel HAR method based on a difference of convex programming (DCP) problem is represented, which manages to handle uncertainty. For this purpose, given an input sensor data stream, a primary belief in each activity is calculated for the sensor events. Since the primary beliefs are calculated based on some abstractions, they naturally bear an amount of uncertainty. To mitigate the effect of the uncertainty, a DCP problem is defined and solved to yield secondary beliefs. In this procedure, the uncertainty stemming from a sensor event is alleviated by its neighboring sensor events in the input stream. The final activity inference is based on the secondary beliefs. The proposed method is evaluated using a well-known and publicly available dataset. It is compared to four HAR schemes, which are based on temporal probabilistic graphical models, and a convex optimization-based HAR procedure, as benchmarks. The proposed method outperforms the benchmarks, having an acceptable accuracy of 82.61%, and an average F-measure of 82.3%.

• The Journal of Korean Physical Therapy
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• v.23 no.2
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• pp.1-5
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• 2011

Purpose: This study examined the difference in the center of pressure (COP) displacement time in older adults according to the obstacle height during stance at each sub.phase when crossing obstacles. Methods: Fifteen older adults were enrolled in this study (${\geq}65$ years of age). The F-scan was used to measure the COP displacement time when crossing a 0, 10 and 40cm obstacle, and the stance phase was divided into 4 sub-phases according to the foot contact pattern. Results: During the stance phase, the COP displacement time increased with increasing obstacle height. During the mid-stance, terminal stance and pre-swing except for the loading response, there were significant differences in the COP displacement time according to the obstacle height. Conclusion: This study suggests that older adults show differences in the COP displacement time according to the stance sub-phase while crossing obstacles, and they use different mechanisms according the sub-phases to maintain balance during obstacle crossing.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.8
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• pp.568-574
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• 2015

The present study was conducted by using stereo pattern recognition method(SPR method) to measure the displacement and vibration of an airplane wing in flight condition. A SPR based measurement system was developed using two visible light stereo cameras. The visible light stereo images were processed to obtain marker points by adaptive threshold method and marker filtering technique. The marker points were used to reconstruct 3D point, displacement, and vibration data. The SPR system was installed on F-16 fighter. The wing displacement and vibration were measured in flight condition. Therefore, this paper presents a possibility that SPR based measurement system using visible light stereo camera can be very useful for measuring displacement and vibration of an airplane in flight condition.

• The Journal of Korea Robotics Society
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• v.13 no.1
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• pp.55-62
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• 2018

In this paper, a method for estimation of external force on an end-effector using joint torque sensor is proposed. The method is based on portion of measure torque caused by external force. Due to noise in the torque measurement data from the torque sensor, a recursive least-square estimation algorithm is used to ensure a smoother estimation of the external force data. However it is inevitable to create a delay for the sensor to detect the external force. In order to reduce the delay, modified recursive least-square is proposed. The performance of the proposed estimation method is evaluated in an experiment on a developed six-degree-of-freedom robot. By using NI DAQ device and Labview, the robot control, data acquisition and The experimental results output are processed in real time. By using proposed modified RLS, the delay to estimate the external force with the RLS is reduced by 54.9%. As an experimental result, the difference of the actual external force and the estimated external force is 4.11% with an included angle of $5.04^{\circ}$ while in dynamic state. This result shows that this method allows joint torque sensors to be used instead of commonly used external sensory system such as F/T sensors.

• Journal of the Korean Society of Clothing and Textiles
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• v.16 no.3 s.43
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• pp.251-256
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• 1992

As a basic expriment to find out the thermal insulation effect of bedding KES-F7 was used to measure. The warmth retaining ratio of the six kinds of filling materials as cotton, wool , silk, down, cotton/polyester was measured, and the infleunce on the warmth retaining ratio of the warmth retaining ratio and humidity by the material was investigated. The results obtained are as follows: 1. The warmth retaining ratio of each filling material was shown to range from $70\%$ to $77\%$ . The warmth retaining ratio of each material preyed to be high in order down> polyester> cotton/polyester>cotton>silk>wool fiber. 2. The warmth retaining ratio of each filling material decreased with the inclose of the humidity The effective reduction rate by filling fiber's was high in order wool>cotton>cotton/polyester>silk>down>polyester material. 3. The warmth retaining ratio of each filling material was shown to be in counter-correlation with the humidity, and the correlation coefficient (r=0.94-0.98) proved to be highly signi-ficant.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.8
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• pp.3725-3748
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• 2018

Text data distribution is often imbalanced. Imbalanced data is one of the challenges in text classification, as it leads to the loss of performance of classifiers. Many studies have been conducted so far in this regard. The proposed solutions are divided into several general categories, include sampling-based and algorithm-based methods. In recent studies, feature selection has also been considered as one of the solutions for the imbalance problem. In this paper, a novel one-sided feature selection known as probabilistic feature selection (PFS) was presented for imbalanced text classification. The PFS is a probabilistic method that is calculated using feature distribution. Compared to the similar methods, the PFS has more parameters. In order to evaluate the performance of the proposed method, the feature selection methods including Gini, MI, FAST and DFS were implemented. To assess the proposed method, the decision tree classifications such as C4.5 and Naive Bayes were used. The results of tests on Reuters-21875 and WebKB figures per F-measure suggested that the proposed feature selection has significantly improved the performance of the classifiers.

• Journal of Information Science Theory and Practice
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• v.2 no.3
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• pp.29-39
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• 2014

In recent years, several studies have proposed making use of the Twitter micro-blogging service to track various trends in online media and discussion. In this study, we specifically examine the use of Twitter to track discussions of food safety in the Korean language. Given the irregularity of keyword use in most tweets, we focus on optimistic machine-learning and feature set selection to classify collected tweets. We build the classifier model using Naive Bayes & Naive Bayes Multinomial, Support Vector Machine, and Decision Tree Algorithms, all of which show good performance. To select an optimum feature set, we construct a basic feature set as a standard for performance comparison, so that further test feature sets can be evaluated. Experiments show that precision and F-measure performance are best when using a Naive Bayes Multinomial classifier model with a test feature set defined by extracting Substantive, Predicate, Modifier, and Interjection parts of speech.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.45-51
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• 1982

An endodontically treated tooth is likely to be brittle than a vital tooth. Internal structure of the tooth has been weakened due to a significant removal of dentin by coronal access, canal preparation. There are many controversies concerning with various methods of reinforcing an intact anterior tooth that has endodontic treatment. In this experiment, 128 extracted maxillary anterior teeth were endodontically treated, and prepared with 4 methods of restorations; Composite resin filling with zinc phosphate cement, composite resin filling without zinc phosphate cement, composite resin filling with post, and metal crown with post. An Instron testing machine was used to measure the fracture loads of the specimens. The means of the failure loads for the 4 groups were compared by F-test statistically and the failure modes were observed. The results were as follows; 1. There were no statistically significant difference between the failure loads of the four methods of restoration. 2. Teeth without post were fractured in a horizontal or oblique plane through upper or middle third of the root. 3. In the posted teeth, fractures were occurred around the post. 4. In the metal crowned teeth with post, the fracture were occurred around the post or coronal area.

• Journal of the Korean Home Economics Association
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• v.28 no.4
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• pp.155-176
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• 1990

The purpose of this study is to investigate the influential factors to home management ability of mothers and their unmarried daughters through researching the relationship of their home management ability. It would provide the basic data for the direction of Home Economics Education. The subjects were 653, from 20 to 30 years of unmarried women and their mothers in Chonbuk province. The questionaire was used to measure their Home Management ability. The measured areas were planing, creativity, consumption management, housework, evaluation, and human relation. The question items were respectively 6 and totally 36. Spss was used for the statistic. Frequency, Percentage, Means, Standard Deviation were used for general understanding. For data analysis, F-test, Pearson Product-moment Correlation, Duncan's Multiple Range Test, Stepwise Multi-regression Analysis were used. Lastly, the research pattern was examined by Path Analysis. The results were as follows. 1. The importnat influential factors to mother's home management ability were their schooling level and their perceived socio-economic status among the general factors(age, shooling level, perceived socio-economic status) and the family atmosphere factors(monthly income, family type). 2. The important influential factors of unmarried daughter's home management ability were the monthly income of their family and the socio-economic status perceived by them, among their mother's general factors, family atmohphere factors, their own general factors(age, schooling level, perceived socio-economics status, occupation, growing place). 3. The influence of mother's home management ability on unmarried daughter's home management ability was much more remarkable than mother's general factors, family atmosphere factors and unmarried daughter's general factors.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.19-26
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• 2011

Previous laboratory studies have shown that prosodic structures are encoded in the modulations of phonetic patterns of speech including suprasegmental as well as segmental features. Drawing on a prosodically annotated large-scale speech data from the Buckeye corpus of conversational speech of American English, the current study first evaluated the reliability of prosody annotation by a large number of ordinary listeners and later examined whether and how prosodic prominence influences the phonetic realization of multiple acoustic parameters in everyday conversational speech. The results showed that all the measures of acoustic parameters including pitch, loudness, duration, and spectral balance are increased when heard as prominent. These findings suggest that prosodic prominence enhances the phonetic characteristics of the acoustic parameters. The results also showed that the degree of phonetic enhancement vary depending on the types of the acoustic parameters. With respect to the formant structure, the findings from the present study more consistently support Sonority Expansion Hypothesis than Hyperarticulation Hypothesis, showing that the lexically stressed vowels are hyperarticulated only when hyperarticulation does not interfere with sonority expansion. Taken all into account, the present study showed that prosodic prominence modulates the phonetic realization of the acoustic parameters to the direction of the phonetic strengthening in everyday conversational speech and ordinary listeners are attentive to such phonetic variation associated with prosody in speech perception. However, the present study also showed that in everyday conversational speech there is no single dominant acoustic measure signaling prosodic prominence and listeners must attend to such small acoustic variation or integrate acoustic information from multiple acoustic parameters in prosody perception.