• Smart Structures and Systems
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• v.7 no.1
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• pp.15-25
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• 2011

The mechanical properties obtained from mechanical tests, such as tensile, buckling, impact and fatigue tests, are largely applied to several materials and are used today for preliminary studies for the investigation of a desired element in a structure and prediction of its behavior in use. This contribution focus on two widely used different tests: tensile and fatigue tests. Small PZT (Lead Titanate Zirconate) patches are bonded on the surface of test samples for impedance-based health monitoring purposes. Together with these two tests, the electromechanical impedance technique was performed by using aluminum test samples similar to those used in the aeronautical industry. The results obtained both from tensile and fatigue tests were compared with the impedance signatures. Finally, statistical meta-models were built to investigate the possibility of determining the state of the structure from the impedance signatures.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.984-987
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• 2018

In an Internet of Thing (IoT) environment, entities with different attributes and capacities are going to be connected in a highly connected fashion. Specifically, not only the mechanical and electronic devices but also other entities such as people, locations and applications are connected to each other. Understanding and managing these connections play an important role for businesses, which identify opportunities for new IoT services. Traditional approach for storing and querying IoT data is used of a relational database management system (RDMS) such as MySQL or MSSQL. However, using RDMS is not flexible and sufficient for handling heterogeneous IoT data because these data have deeply complex relationships which require nested queries and complex joins on multiple tables. In this paper, we propose a graph model for constructing a graph database of heterogeneous IoT data. Graph databases are purposely-built to store highly connected data with nodes representing entities and edges representing the relationships between these entities. Our model fuses social graph, spatial graph, and things graph, and incorporates the relationships among them. We then present a case study which applies our model for representing data from a Smart Campus using Neo4J platform. Through the results of querying to answer real questions in Smart Campus management, we show the viability of our model.

• Advances in aircraft and spacecraft science
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• v.9 no.6
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• pp.553-569
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• 2022

In this article, we propose a criterion for ensuring the asymptotic stability of large multiple delays, based on the direct Lyapunov method. Based on this criterion and distributed control scheme, the controllers are synthesized by the PDC to stabilize these large-scale systems with multiple delays. And we focus on the results which shows the high effective by the proposed theory utilized for damage propagation for aircraft structural analysis of composite materials. Finally, the numerical simulations confirmed the effectiveness of the method.

• Architectural research
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• v.19 no.2
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• pp.27-33
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• 2017

Advances in information and mobile technologies have changed the traditional firm ways of working very flexible, collaborative and innovative, resulting in the changes in work place structures and layouts. Despite the growing body of literature examining the novel ways of working, which is called smart work, there is little academic attentions paid to the spatial aspects of new work places, namely smart offices and smart work centers. This research explores the spatial changes of work places that improve business efficiency and collaboration among workers suitable for the novel ways of working. Conducting in-depth field surveys on selected cases, we analyzed the changes in spatial structure and operation policies of smart offices and smart work centers. From this survey, we observed that the new work places under study take various novel spatial forms and they have flexible operating policies such as flexible seating and flexible work hours. We also found that it would be difficult to change existing business practices and typical ways of performing tasks, without changing the bureaucratic spatial designs and layouts. Future studies are suggested to examine how spatial structures and layouts of offices have impacts on space utilization, collaboration, creativity, and job satisfaction.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.846-851
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• 2017

Piezoelectricity is the capability of a piezoelectric material to change mechanical energy into electrical energy. The determination of electrical and mechanical properties plays a significant role in characterizing the piezoelectric material. The energy losses characteristics of piezoelectric material can be described by mechanical quality factor. In this paper, the output voltage and mechanical quality factor of Lead Zirconate Titanate (PZT-4A) piezoelectric material is determined under various resistance and loading conditions by using the test setup. The commercial FEM software ABAQUS is used to analyze the performance of piezoelectric material under static loading conditions. It is observed that these properties affect the performance of a material particularly in the designing of smart structures. The experimental results are partially compared to the simulation values.

• Smart Structures and Systems
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• v.3 no.1
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• pp.23-49
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• 2007

Wavelet transforms are the emerging signal-processing tools for damage identification and time-frequency localization. A small perturbation in a static or dynamic displacement profile could be captured using multi-resolution technique of wavelet analysis. The paper presents the wavelet analysis of damaged linear structural elements using DB4 or BIOR6.8 family of wavelets. Starting with a localized reduction of EI at the mid-span of a simply supported beam, damage modeling is done for a typical steel and reinforced concrete beam element. Rotation and curvature mode shapes are found to be the improved indicators of damage and when these are coupled with wavelet analysis, a clear picture of damage singularity emerges. In the steel beam, the damage is modeled as a rotational spring and for an RC section, moment curvature relationship is used to compute the effective EI. Wavelet analysis is performed for these damage models for displacement, rotation and curvature mode shapes as well as static deformation profiles. It is shown that all the damage indicators like displacement, slope and curvature are magnified under higher modes. A localization scheme with arbitrary location of curvature nodes within a pseudo span is developed for steady state dynamic loads, such that curvature response and damages are maximized and the scheme is numerically tested and proved.

• Journal of Convergence Society for SMB
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• v.6 no.3
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• pp.79-83
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• 2016

The purpose of this study is to provide customized information to student which study and live in a university campus. In this study, we collect internal data of campus and external data on the Internet such as the blog or SNS and, then store and process them. After that, we propose a system for providing individual students one-to-one marketing by analyzing these data in detail. This system analyzes purchase history information and the attendance of the building, and then transmits the coupon and information individually according to the pattern to the student's mobile phone.

• Journal of Internet Computing and Services
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• v.20 no.5
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• pp.79-86
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• 2019

This paper is an overview of key elements of Korea National Open University's smart mobile learning system, and an attempt to evaluate its main services relative to the FRAME model and the Mobile Learning Development Model for distance learning in higher education. KNOU improved its system architecture to one based on xMOOC e-learning content delivery while also upgrading its PC-based online/mobile learning services to facilitate an easier and more convenient access to lectures and for better interactivity. From the users' viewpoint, the upgraded 'U-KNOU Campus' allows for a more integrated search capability coupled with better course recommendations and a customized notification service. Using the new system, the students can access not only the school- and peer-issued messages via online bulletin boards but also share information and pose questions to others including to the school faculty/officials and system administrators. Additionally, a new mobile payment method has been incorporated into the system so that the students can select and pay for additional courses from anywhere. In spite of these advances, the issue of device usability and content development remain; specifically U-KNOU Campus needs to improve its instructor-learner and learner-to-learner interactivity and mobile evaluation interface.

• Journal of Digital Convergence
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• v.10 no.5
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• pp.27-35
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• 2012

The importance of smart learning (SL) has been emphasized in schools. Additionally, the significance of smart work (SW) in improving business performance has gained much attention among industries. From theoretical, technological, and environmental perspectives, SL and SW are somewhat similar. Therefore, a case study was performed to find a way to link SL and SW, and a linking model was proposed for this purpose. Because laptops are considered a pivotal element in the technological aspect of SL, graduate students' use of personal laptops in classes (Bring Your Own Laptop, BYOL) was investigated. The results showed that the students reacted positively to the idea of using personal laptops in class and that they expected to learn IT skills more effectively this way. They listed being able to study even after class and the easy accessibility of relevant data as the strengths of BYOL. However, they cited the heaviness of the laptops and occasional loss of focus during classes as the weaknesses of BYOL. Thus, this study showed the possibility of that students who experience SL can perform better in an SW situation. Therefore, if a policy is enacted that allows students to efficiently use laptops, a greater number of educational achievements will be attained on smart campuses and, subsequently, a greater number of smart workers will be produced.

• Journal of Digital Convergence
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• v.12 no.4
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• pp.21-32
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• 2014

Recently, the number of Koreans who use smartphones has increased drastically; many use smartphones to learn English. In this study, one hundred Korean adult ELT (English language teaching) learners were surveyed to investigate their use of smartphones and factors influencing such use. For comparison, sixty-two students of a Korean cyber university were surveyed; these students were able to study using their smartphones in a smart campus environment. The research results showed that both groups positively used smartphones frequently, and that many intended to continue using them. With regard to ELT, both groups intended to learn English using their smartphones. Furthermore, they preferred certain types of ELT content: thirty-minute or less learning sessions, receptive English skills that focused on listening and reading, and short units of framed language items such as pronunciation and vocabulary. However, few of the respondents in both groups installed ELT apps on their smartphones, and few of the ELT apps satisfied them. The cyber university students responded similarly about smartphone use, although their responses regarding smartphone use for ELT purposes were less positive. These results indicate that the goal of cyber universities in achieving optimum learning outcomes through smart learning and the smart campus has not yet been realized.