• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.4
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• pp.351-359
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• 2011

In a structure, damage can occur at several scales from micro-cracking to corrosion or loose bolts. This makes the identification of damage difficult with one mode of sensing. Hence, a multi-mode actuated sensing system is proposed based on a self-sensing circuit using a piezoelectric sensor. In the self sensing-based multi-mode actuated sensing, one mode provides a wide frequency-band structural response from the self-sensed impedance measurement and the other mode provides a specific frequency-induced structural wavelet response from the self-sensed guided wave measurement. In this study, an experimental study on the pipeline system is carried out to verify the effectiveness and the robustness of the proposed structural health monitoring approach. Different types of structural damage are artificially inflicted on the pipeline system. To classify the multiple types of structural damage, a supervised learning-based statistical pattern recognition is implemented by composing a two-dimensional space using the damage indices extracted from the impedance and guided wave features. For more systematic damage classification, several control parameters to determine an optimal decision boundary for the supervised learning-based pattern recognition are optimized. Finally, further research issues will be discussed for real-world implementation of the proposed approach.

• Journal of Korean Dental Hygiene Science
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• v.2 no.2
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• pp.31-39
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• 2019

Background: The purpose of this study was to investigate the effect of self-perception of halitosis on oral health behaviors of college students according to whether they worked in a non-service or service-related job. Methods: A self-reporting questionnaire of 150 university students working in service jobs and 150 university students working in non-service jobs in the metropolitan area was conducted from 26th April to 5th May 2018. The survey tool consisted of 3 general topic areas. There were 5 questions on oral health awareness behavior, 3 questions related to their self-perception of halitosis, and 8 questions on their oral health care practice. All were measured on the Likert 5-point scale. The frequency of their oral health behaviors and their self-perception of halitosis were analyzed according to the subjects' occupation. Pearson's correlation analysis and a linear regression analysis were conducted to confirm the influence of the two. The significance level for the statistical significance test was set to α = 0.05 (two-tailed). Results: In both the service and non-service groups, a coated tongue and food debris were found to influence halitosis(x²=10.95, p=0.027). According to the t-test, taking into account the self-perception of halitosis and oral health behaviors, both were higher in those that had a service job. Self-perception of halitosis and oral health behaviors were found to have a negative correlation(γ=-0.11, p<0.05). As the self-perception of halitosis increased, oral health care practices also increased(Beta=-0.185, p=0.020). Conclusions: Systematic interventions such as oral health programs and health promotion are needed to improve the oral health of service workers.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.1
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• pp.86-90
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• 2008

Ubiquitous Smart pace connects many kinds of smart object to satisfy user's demands. Thus, not only excessive loads but also resource collisions occur among service objects while configurating services to fulfill the user's request. After all, as malfunction occurs between service objects, it offers wrong service to user or does not respond to service request. To solve these problems, Ubiquitous Smart Space is observed by monitoring system of function, performance, and status of objects. Therefore, optimized function, performance and duality of service of smart space service for user should be improved by recording log and analyzing recorded the log. In this paper, we suggest a novel monitoring system to optimize performance according to pattern of diverse services and execute self-recovery on system down and malfunction.

• Science of Emotion and Sensibility
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• v.11 no.2
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• pp.181-192
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• 2008

The purpose of this study was to examine the outdoorwear satisfaction of silver consumers and their purchase behavior according to age. The survey participants in this study were 100 elders who were climbing the Bukhan mountain; 68 among them were new silver group in range of 55-64 years old. As the subjects were old people who had a relatively low level of cognitive ability, self-administration method and interview were employed together. The collected data were analyzed with t-Test and x2 -test. The results follow: the new silver group had purchased more and spent more money on outdoorwear. The brand recognition, purchase place, purchase criteria, and dissatisfaction factors of silver groups were different from those from new silver groups. The quality and design/color were thought to be needed for improvement for a new silver group, while quality and comfort/wearability were for silver group.

• Education of Primary School Mathematics
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• v.20 no.2
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• pp.153-162
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• 2017

This study examined elementary pre-service teachers' (PSTs') perceived preparedness of high-leverage practices (HLPs) in mathematics teaching. Eighty-one elementary PSTs who enrolled in four sections of an elementary mathematics methods course at a Midwestern University in the United States participated in a survey that inquired their self-reported confidence and competence levels on HLPs. This study specifically investigated the comparison between PSTs' perceptions of HLPs and the mathematics teacher educators' expectations. Findings show several glaring differences between the PSTs' perceptions and experts' perceptions in regards to the complexity of some HLPs. This study suggests that initial teacher training programs should include more specific investment in PSTs' insights into details of each teaching practice in mathematics by deliberate decompositions.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.217-228
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• 2011

In centralize CDN systems, the content server selection is performed by service node for every user request, and the selected node is notified to the user. In this paper, we present distributed CDN architecture and algorithm in which the request from a user is delivered to the content source by a P2P algorithm utilizing DHT(distributed hash table) through the overlay network and the user selects one of the source nodes based on real-time user-centric criteria. For this purpose, we propose a modified Pastry algorithm for contents registration, search and selection, in addition to the distributed architecture. The proposed architecture has the advantages of load balancing, traffic balancing, scalability, fault-tolerance due to the self-configuration, self-healing attributes of distributed architecture. Various simulation shows the feasibility of the proposed architecture and algorithm, and the performance is compared and discussed for the variations of the proposed scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.4B
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• pp.200-207
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• 2007

Many P2P systems which are designed to implement large-scale data sharing have been introduced in internet recently. They exhibit interesting features like sell-configuration, sell-healing and complete decentralization, which make them appealing for deployment in ad hoc environments as well. This paper proposes an Gnutella-based P2P system that can operate efficiently in ad hoc networks. The objectives of this paper are to extend the overall system lifetime, to reduce overheads, and to provide enhanced performance. The proposed system uses an ultrapeer election scheme based on metric values and proactive distribution of ultrapeer information. According to the simulation results, the proposed system can provide better performance than Gnutella in terms of query success rate, query response time, overhead and residual battery power by utilizing network resources efficiently.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.4
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• pp.303-309
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• 2010

We proposes a new approach for testing the self visual-acuity by using the KS standard optotype. The proposed system provides their hand-gesture recognition method for the convenient response of subjects in the visual acuity measurement. Also, this system can measure a visual-acuity that excludes the examiner's subjective judgement or the subject's memorized guess, because of presenting a random optotype automatically by computer without a examiner. Especially, Our system guarantees the reliability by using the KS standard optotype and its presentation(KS P ISO 8596), which is defined by the Korea Standards Association in 2006. And the database management function of our system can provide the visual-acuity data to the EMR client easily. As a result, Our system shows the 98% consistency in the limit of the ${\pm}1$ visual-acuity level error by comparing the visual-acuity chart test.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.6
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• pp.301-308
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• 2018

This paper presents an optimal design method of a hybrid structural control system considering multi-hazard. Unlike a typical structural control system in which one system is designed for one specific type of hazard, a simultaneous optimal design method for both active and passive control systems is proposed for the mitigation of seismic and wind induced vibration responses of structures. As a numerical example, an optimal design problem is illustrated for a hybrid mass damper(HMD) and 30 viscous dampers which are installed on a 30 story building structure. In order to solve the optimization problem, a self-adaptive Harmony Search(HS) algorithm is adopted. Harmony Search algorithm is one of the meta-heuristic evolutionary methods for the global optimization, which mimics the human player's tuning process of musical instruments. A self-adaptive, dynamic parameter adjustment algorithm is also utilized for the purpose of broad search and fast convergence. The optimization results shows that the performance and effectiveness of the proposed system is superior with respect to a reference hybrid system in which the active and passive systems are independently optimized.

• Journal of Digital Convergence
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• v.18 no.12
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• pp.459-468
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• 2020

This study was examined to identify effects of compliance with preventive behavior on COVID-19 of nursing college students. From April 24 to May 6, 2020, 195 nursing students in grades 1-4 responded to an online self-report questionnaire. Collected data were analyzed by descriptive statistics, t-test, ANOVA, Pearson's correlation coefficients, and multiple regression using SPSS/WIN 23.0 program. The result showed that compliance with preventive behavior was positively correlated with knowledge and anxiety. The multiple regression revealed knowledge(β=.418, p<.001), anxiety(β=.280, p<.001), and experience of self quarantine(β=-.107, p<.05) to be significant compliance with preventive behavior. These variables accounted for 40.4% of compliance with preventive behavior. Conclusion Accurate and positive knowledge formation of COVID-19 of nursing students is necessary and the development and application of educational programs that can practice the performance of preventive actions in everyday life is necessary.