• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1540-1546
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• 2014

In order to resolve coverage hole problems caused by indoor-BS (IBS) faults, we propose a new frame structure and practical algorithm based on optimization technique. Our main contributions can be described as follows: 1) a frame structure with healing channels for solving abnormal IBS faults; and 2) an efficient heuristic resource allocation algorithm with fixed IBS selection to reduce the complexity for the optimization problem. Through intensive simulations, we evaluate the performance excellency of our proposed algorithm with respect to average cell capacity and user fairness compared with conventional algorithms.

• Smart Structures and Systems
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• v.14 no.2
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• pp.191-207
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• 2014

In this research, an internal model based method is proposed to estimate the structural displacements and velocities under ambient excitation using only acceleration measurements. The structural response is assumed to be within the linear range. The excitation is assumed to be with zero mean and relatively broad bandwidth such that at least one of the fundamental modes of the structure is excited and dominates in the response. Using the structural modal parameters and partial knowledge of the bandwidth of the excitation, the internal models of the structure and the excitation can be respectively established, which can be used to form an autonomous state-space representation of the system. It is shown that structural displacements, velocities, and accelerations are the states of such a system, and it is fully observable when the measured output contains structural accelerations only. Reliable estimates of structural displacements and velocities are obtained using the standard Kalman filtering technique. The effectiveness and robustness of the proposed method has been demonstrated and evaluated via numerical simulations on an eight-story lumped mass model and experimental data of a three-story frame excited by the ground accelerations of actual earthquake records.

• Smart Structures and Systems
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• v.23 no.3
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• pp.279-293
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• 2019

To ensure high quality data being used for data mining or feature extraction in the bridge structural health monitoring (SHM) system, a practical sensor fault diagnosis methodology has been developed based on the similarity of symmetric structure responses. First, the similarity of symmetric response is discussed using field monitoring data from different sensor types. All the sensors are initially paired and sensor faults are then detected pair by pair to achieve the multi-fault diagnosis of sensor systems. To resolve the coupling response issue between structural damage and sensor fault, the similarity for the target zone (where the studied sensor pair is located) is assessed to determine whether the localized structural damage or sensor fault results in the dissimilarity of the studied sensor pair. If the suspected sensor pair is detected with at least one sensor being faulty, field test could be implemented to support the regression analysis based on the monitoring and field test data for sensor fault isolation and reconstruction. Finally, a case study is adopted to demonstrate the effectiveness of the proposed methodology. As a result, Dasarathy's information fusion model is adopted for multi-sensor information fusion. Euclidean distance is selected as the index to assess the similarity. In conclusion, the proposed method is practical for actual engineering which ensures the reliability of further analysis based on monitoring data.

• Smart Structures and Systems
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• v.30 no.3
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• pp.273-286
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• 2022

In recent years, vision-based monitoring has received great attention. However, structural identification using vision-based displacement measurements is far less established. Especially, simultaneous identification of structural systems and unknown excitation using vision-based displacement measurements is still a challenging task since the unknown excitations do not appear directly in the observation equations. Moreover, measurement accuracy deteriorates over a wider field of view by vision-based monitoring, so, only a portion of the structure is measured instead of targeting a whole structure when using monocular vision. In this paper, the identification of structural system and excitations using vision-based displacement measurements is investigated. It is based on substructure identification approach to treat of problem of limited field of view of vision-based monitoring. For the identification of a target substructure, substructure interaction forces are treated as unknown inputs. A smoothing extended Kalman filter with unknown inputs without direct feedthrough is proposed for the simultaneous identification of substructure and unknown inputs using vision-based displacement measurements. The smoothing makes the identification robust to measurement noises. The proposed algorithm is first validated by the identification of a three-span continuous beam bridge under an impact load. Then, it is investigated by the more difficult identification of a frame and unknown wind excitation. Both examples validate the good performances of the proposed method.

• Smart Structures and Systems
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• v.31 no.5
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• pp.455-467
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• 2023

Impact damper is a passive damping system that controls undesirable vibration with mass block impacting with stops fixed to the excited structure, introducing momentum exchange and energy dissipation. However, harmful momentum exchange may occur in the random excitation increasing structural response. Based on the mechanism of impact damping system, a semi-active impact damper (SAID) with controllable impact timing as well as a semi-active control strategy is proposed to enhance the seismic performance of engineering structures in this paper. Comparative experimental studies were conducted to investigate the damping performances of the passive impact damper and SAID. The extreme working conditions for SAID were also discussed and approaches to enhance the damping effect under high-intensity excitations were proposed. A numerical simulation model of SAID attached to a frame structure was established to further explore the damping mechanism. The experimental and numerical results show that the SAID has better control effect than the traditional passive impact damper and can effectively broaden the damping frequency band. The parametric studies illustrate the mass ratio and impact damping ratio of SAID can significantly influence the vibration control effect by affecting the impact force.

• Journal of the Korea Convergence Society
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• v.9 no.5
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• pp.21-26
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• 2018

In this study, HRD-NET (http://hrd.go.kr), a vocational and training integrated computer network operated by the Ministry of Employment and Labor, is used to confirm whether job training information required by job seekers is being provided smoothly The question bulletin board was extracted using 'R' program which is optimized for big data technique. Therefore, the effectiveness, appropriateness, visualization, frequency analysis and association analysis of the vocational training system were conducted through this, The results of the study are as follows. First, the issue of vocational training card, video viewing, certificate issue, registration error, Second, management and processing procedures of learning cards for tomorrow 's learning cards are complicated and difficult. In addition, it was analyzed that the training cost system and the refund structure differentiated according to the training occupation, the process, and the training institution in the course of the training. Based on this paper, we will study not only the training system of the Ministry of Employment and Labor but also the improvement of the various training computer system of the government department through the analysis of big data.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.5
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• pp.162-172
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• 2008

In this paper, we propose a multimodal speaker verification method using teeth image and voice as biometric trait for personal verification in mobile terminal equipment. The proposed method obtains the biometric traits using image and sound input devices of smart-phone that is one of mobile terminal equipments, and performs verification with biometric traits. In addition, the proposed method consists the multimodal-fashion of combining two biometric authentication scores for totally performance enhancement, the fusion method is accompanied a weighted-summation method which has comparative simple structure and superior performance for considering limited resources of system. The performance evaluation of proposed multimodal speaker authentication system conducts using a database acquired in smart-phone for 40 subjects. The experimental result shows 8.59% of EER in case of teeth verification 11.73% in case of voice verification and the multimodal speaker authentication result presented the 4.05% of EER. In the experimental result, we obtain the enhanced performance more than each using teeth and voice by using the simple weight-summation method in the multimodal speaker verification system.

• Smart Media Journal
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• v.11 no.8
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• pp.21-28
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• 2022

Currently, as we enter the 21st century, the level and interest of society, culture, economy, and science are rapidly developing, but science education is still struggling. In order to increase the efficiency of science education, it is most important to focus on elementary education based on basic science. Therefore, this study aims to analyze the main causes of Korea's science museum's regression as a museum focusing on experience, interest, and fun such as simple science experience centers and science theme parks. To this end, the influencing factors were identified by applying the algorithm of the actor-based model based on the data on the exhibition space and the exhibition movement of the science museum completed and operated in Korea over the past 5 years, and the problem of the visitor movement in the exhibition space was analyzed through the space system. In this study, it was confirmed that the exhibition environment was the best when the linear plot movement system and the picalesque plot were applied simultaneously in the museum's exhibition narrative theory, and the arrangement of major exhibition spaces, width of exhibition spaces, and separation of spaces for exhibition purposes were derived.

• Journal of Convergence for Information Technology
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• v.10 no.9
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• pp.1-7
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• 2020

In order to implement a smart factory for manufacturing innovation, more digital twins will be developed and applied gradually. In particular, simulation and optimization of digital twins makes it possible to support critical decision-making like a predictive maintenance of the equipment for manufacturing. In terms of a user perspective, this study suggests the conceptual framework of Digital Twin Management System (DTMS) for supporting the analytical and managerial activities for Digital Twins. We integrate the methods and structure of the area like Manufacturing Engineering, Decision Support Systems, and Optimization for developing the DTMS. The framework suggested in this study shows a typical DSS which consists of dialog management system, model management system and data management system. It also includes Analytical Digital Twins and simulations & optimization module. The framework is being applied in one of the most competitive and complex industrial sector. Also this study is meaningful to suggest a new direction of research.

• Journal of the Ergonomics Society of Korea
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• v.31 no.1
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• pp.93-100
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• 2012

Objective: This study is to review the current state of services offered to pharmacy users, and develop a service design converging a prescription service and a smart phone application service in order to enhance patients' experience at pharmacies and home. Background: Under the new medical system; separation of prescribing and dispensing drugs, a doctor writes a prescription to their patients and patients have their prescription filled at the pharmacy. As the number of flue, allergy and atopy patients has increased, waiting lines have been longer at pharmacies. Besides, the current medical service system lacks of providing proper information on prescribed pills to patients. There are already services offered during waiting times such as offering free drinks, magazines or suggesting general drugs which you can buy without prescription, however they neither cover the current medical service's shorts nor shorten the waiting time. Method: I researched objective and perceived waiting times reduction methods, the current service status at pharmacies, and the government's policy direction in a medical service. Also, I observed a patient's journey from the hospital to pharmacy and then home. I examined the circumstance at pharmacies, patients' behaviors and their thoughts during their journey, and extracted three main goals to design a service in order to help patients have positive perception during the waiting time; (1) to reduce the perceived time by the way of visualizing time and offering readings about what patients consider necessary, (2) to educate patients what they are into and how to get through, (3) to establish trust among patients, doctors and pharmacists. Based on three goals, I designed a structure and a wireframe for a new service application of smart phones. Results: With a new service design for pharmacy users, users can track their medical record and visit the information about their current medical treatments anytime. Also the service helps patients build reliable relationships with doctors and pharmacists. Conclusion: Experience is not just an activity but series of multiple activities. The serving range of a medical service should not be determined by stakeholders but user's holistic experience. By approaching a service design with a holistic vision, it can enrich not only a temporary experience but also a whole life well being. Application: Since there are already many service applications advising patients about their illness and finding right doctors, this service design is focused on the experience from getting a prescription till feeling better. The next move is to combine those two parts medical services and design an integrated service application. As a prescription is going to be coded in numbers, we might consider to design an un-attended pharmacy which can shorten huge amount of time for filling prescriptions.