• Journal of Information Processing Systems
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• v.14 no.3
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• pp.709-726
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• 2018

Database classification is an important preprocessing step for the multi-database mining (MDM). In fact, when a multi-branch company needs to explore its distributed data for decision making, it is imperative to classify these multiple databases into similar clusters before analyzing the data. To search for the best classification of a set of n databases, existing algorithms generate from 1 to ($n^2-n$)/2 candidate classifications. Although each candidate classification is included in the next one (i.e., clusters in the current classification are subsets of clusters in the next classification), existing algorithms generate each classification independently, that is, without taking into account the use of clusters from the previous classification. Consequently, existing algorithms are time consuming, especially when the number of candidate classifications increases. To overcome the latter problem, we propose in this paper an efficient approach that represents the problem of classifying the multiple databases as a problem of identifying the connected components of an undirected weighted graph. Theoretical analysis and experiments on public databases confirm the efficiency of our algorithm against existing works and that it overcomes the problem of increase in the execution time.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.1
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• pp.71-78
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• 1998

The eigenvalue problem is presented for the building with added viscoelastic dampers by using component mode method. The Lagrange multiplier formulation is used to derive the eigenvalue problem which is expressed with the natural frequencies of the building, the mode components at which the dampers are added, and the viscoelastic property of the damper. The derived eigenvalue problem has a nonstandard form for determining the eigenvalues. Therefore, the problem is examined by the graphical depiction to give new insight into the eigenvalues for the building with added viscoelastic dampers. Using the present approach the exact eigenvalues can be found and also upper and lower bounds of the eigenvalues can be obtained.

• PNF and Movement
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• v.17 no.2
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• pp.223-236
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• 2019

Purpose: This research was to develop a module for problem-based learning(PBL) and to enhance the problem-solving abilities of physical therapy students in a neurological physical therapy course and to evaluate the effects of the module using quantitative and qualitative data. Methods: The PBL module was applied to 55 third-year physical therapy students who participated in a neurological physical therapy course at S university in Seoul. Anonymous self-report questionnaires and reflection journals were collected, and the data were analyzed. Results: The results of the analysis showed that the academic achievements of the students who participated in the first PBL class improved compared to the academic achievements of the students who had participated in the same class in the previous semester. Second, the students who participated in the PBL class evaluated the PBL as a very effective learning method for developing clinical practical ability. Third, the students of the PBL class showed increased cooperation and communication abilities between team members. Conclusion: The results of this study indicated that, if PBL class case studies and various types of teaching and learning methods appropriate for theoretical and practical fields are continuously studied, then it is expected that teaching models will be developed that can develop flexibility and creativity among preliminary physical therapists in a rapidly changing medical environment.

• Journal of the Korean Society of Mechanical Technology
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• v.20 no.6
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• pp.924-928
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• 2018

The objective of this study is to solve a problem that is occurred during the spline machining of tubular shaft yoke in both side IMS module. In order to simulate the problem, the movement direction of upper die was set as standard case and error case. The material of tubular shaft yoke was set to S20C as refer to the analysis library. The movement directions of upper die were separated with standard case and error case. The error case was set to simulate the problem in the spline machining of tubular shaft yoke. In order to solve the problem, the outer radius of upper die were modelled from 9.40mm to 9.44mm. The simulation results were analyzed and compared in terms of effective stress, metal flow line and folding phenomena characteristics. In case of the outer radius of upper die was 9.42mm, it was observed a relatively uniform effective stress distribution and had a straight metal flow line.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.1 no.1
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• pp.47-65
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• 1991

An ID-based scheme provides a very efficient solution to the key distribution problem, since it can solve bothe the authentication problem and the communication complexity problem in a public key scheme. Especilly, and ID-Based ndninterative key distribution system plays an crucial roie in the one-way communication environment such as secure electronic mail, owing to its noninteractiveness. This paper aims at analyzing the previously proposed scheme s and providing possible improvements. It also demonstraes that the Maurey-Yacobi's scheme presented in Eurocry'91 is not secure, and provikdes an countemeasure to overcome the security problem.

• Structural Engineering and Mechanics
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• v.82 no.3
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• pp.401-416
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• 2022

The aim of this study is to examine the frictionless double receding contact problem for two functionally graded (FG) layers pressed with a uniformly distributed load and resting on a homogeneous half plane (HP) using analytical and numerical methods. The FG layers are made of a non-homogeneous material with an isotropic stress-strain law with exponentially varying properties. It is assumed that the contact at the FG layers and FG layer-HP interface is frictionless. The body force of the FG layers and homogeneous HP are ignored in the study. Firstly, an analytical solution for the contact problem has been realized using the theory of elasticity and the Fourier integral transform techniques. Then, the problem modeled and two-dimensional analysis was carried out by using the ANSYS package program based on FEM. Numerical results for contact lengths and contact pressures between FG layers and FG layer-HP were provided for various dimensionless quantities including material inhomogeneity, distributed load width, the shear module ratio, and the heights of the FG layers for both methods. The results obtained using FEM were compared with the results found using the analytical formulation. It was found that the results obtained from analytical formulation were in perfect agreement with the FEM study.

• Structural Engineering and Mechanics
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• v.85 no.5
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• pp.621-633
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• 2023

The major objective of this paper is to study the receding contact problem between two functional graded layers under a flat indenter. The gravity is assumed negligible, and the shear moduli of both layers are assumed to vary exponentially along the thickness direction. In the absence of body forces, the problem is reduced to a system of Fredholm singular integral equations with the contact pressure and contact size as unknowns via Fourier integral transform, which is transformed into an algebraic one by the Gauss-Chebyshev quadratures and polynomials of both the first and second kinds. Then, an iterative speediest descending algorithm is proposed to numerically solve the system of algebraic equations. Both semi-analytical and finite element method, FEM solutions for the presented problem validate each other. To improve the accuracy of the numerical result of FEM, a graded FEM solution is performed to simulate the FGM mechanical characteristics. The results reveal the potential links between the contact stress/size and the indenter size, the thickness, as well as some other material properties of FGM.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.5
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• pp.1503-1515
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• 2023

This paper considers the jointly active and passive beamforming design in the IRS-aided MISO downlink vehicle communication system where both V2I and V2V communication paradigms coexist. We formulate the problem as an optimization problem aiming to minimize the total transmit power of the base station subject to SINR requirements of both V2I and V2V users, total transmit power of base station and IRS's phase shift constraints. To deal with this non-convex problem, we propose a method which can alternately optimize the active beamforming at the base station and the passive beamforming at the IRS. By using first-order Taylor expansion, matrix analysis theory and penalized convex-concave process method, the non-convex optimization problem with coupled variables is converted into two decoupled convex sub-problems. The simulation results show that the proposed alternate optimization algorithm can significantly decrease the total transmit power of the vehicle base station.

• Journal of the Health Care and Life Science
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• v.10 no.2
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• pp.237-242
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• 2022

The purpose of this study is to explore an effective learning process by applying PBL to the subject of welfare theory for the disabled. To this end, 'Welfare Measures for the Severely Disabled in the Situation of COVID-19' was conducted as a class on the welfare of the disabled. A total of 20 students participated in the PBL class, and data were collected and analyzed through individual learning activities, group learning activities, evaluation papers, and reflection journals. The analysis results showed the effectiveness of the PBL class in the learners' problem-solving ability, self-directed learning ability, critical thinking ability, and cooperative learning ability. Based on the results of this study, a method for applying problem-focused learning (PBL) to social welfare subjects was suggested.

• Human Ecology Research
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• v.62 no.3
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• pp.427-439
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• 2024

The purpose of this study was to analyze the financial portfolios of single-person households. For the analysis, The purpose of this study is to verify the mediation effect of stress-coping strategies in the relationship between ego-resiliency and burn-out among childcare center teachers. The subjects were 255 childcare center teachers in Gyeongbuk Province. The measurement tools used for this study include ego-resiliency, burn-out, and stresscoping strategy questionnaires. The collected data points were analyzed via Structural Equation Modeling(SEM), Bootstrapping, Pearson Correlation, using SPSS 21.0 and AMOS 20.0 The results of the study analyzing the Structural Equation Model are as follows. First, teachers' ego-resiliency had a negative influence on burn-out. Second, teachers' problem-focused coping strategies had a negative influence on burn-out, while emotionfocused coping strategies had a positive influence on burn-out. Third, teachers' ego-resiliency had a positive influence on both problem-focused and emotion-focused coping strategies. Fourth, teachers' ego-resiliency had an indirect effect on burn-out by improving both problem-focused and emotion-focused coping strategies. This study suggests that education on the use of problem-focused coping strategies in stressful situations is necessary to successfully manage childcare teachers' burn-out in childcare settings in which mandatory evaluation systems are newly implemented.