• Journal of applied mathematics & informatics
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• v.42 no.4
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• pp.945-968
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• 2024

This study focuses on SIR model for SARS-CoV-2. The SIR model classifies a population into three compartments: susceptible S(t), infected I(t), and recovered R(t) individuals. The SARS-CoV-2 model considers various factors, such as immigration, birth rate, death rate, contact rate, recovery rate, and interactions between infected and healthy individuals to explore their impact on population dynamics during the pandemic. To analyze this model, we employed two powerful semi-analytical methods: the Laplace Adomian decomposition method (LADM) and the differential transform method (DTM). Both techniques demonstrated their efficacy by providing highly accurate approximate solutions with minimal iterations. Furthermore, to gain a comprehensive understanding of the system behavior, we conducted a comparison with the numerical simulations. This comparative analysis enabled us to validate the results and to gain valuable understanding of the responses of SARS-CoV-2 model across different scenarios.

• Journal of Industrial Technology
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• v.13
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• pp.25-31
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• 1993

This paper presents an analysis of microwave device component. An H-Plane waveguide component with arbitrary shape is analyzed using finite element method(FEM) cooperated with boundary element method(BEM). The finite element method(FEM) is applied to the junction region and the boundary element method(BEM) to the waveguide region. For the application of BEM in the waveguide structure, a ray representation of the waveguide Green's function is used. The proposed technique was applied to the analysis of the waveguide inductive junction to compare the numerical result with the result of the mode matching technique. The comparison showed good agreements between the two results. Transmitted powers were also computed in T-junction waveguides for the various shape of the junction area.

• Journal of Korean Society for Quality Management
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• v.39 no.2
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• pp.234-243
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• 2011

Multivariate control charts are widely used to monitor the performance of a multivariate process over time to maintain control of the process. Although existing multivariate control charts provide control limits to monitor the process and detect any extraordinary events, it is a challenge to identify the causes of an out-of-control alarm when the number of process variables is large. Several fault identification methods have been developed to address this issue. However, these methods require a normality assumption of the process data. In the present study, we propose a bootstrapped-based $T^2$ decomposition technique that does not require any distributional assumption. A simulation study was conducted to examine the properties of the proposed fault identification method under various scenarios and compare it with the existing parametric $T^2$ decomposition method. The simulation results showed that the proposed method produced better results than the existing one, especially in nonnormal situations.

• Journal of Practical Engineering Education
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• v.5 no.2
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• pp.177-183
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• 2013

In this paper we investigate the history of the education based on STEM which is one of the topics of teaching method of Mathematics and Science oriented to the student, Hand-on education be applying partly to college education and the case of the education of the subject "Mathematics and Science for Engineering" of Japan's college. The educational method based on STEM make the student to recognize by themselves the necessity of the mathematics in the study of the technological and engineering problem, and furthermore draw a conclusion which is the proper method to change from passive to positive the study attitude for the mathematics. But it is more or less unreasonable to apply directly to college education with not physical fusion but chemical fusion of S (science), T (technology), E (engineering) and M (mathematics). Therefore we make themselves to find T and E considered at graduation works. We propose Pseudo-STEM teaching method linking this recognition obtained through self-activity to the mathematics subject.

• Journal of Korean Clinical Nursing Research
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• v.15 no.1
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• pp.67-77
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• 2009

Purpose: This study was aimed to investigate the effects of Lebed method exercise (LME) on nurses' depression, anxiety and stress. The LME is a therapeutic exercise and movement program developed by Sherry Lebed Davis and expected to lessen the stress level of nurses and enhance the nursing job's satisfaction and efficiency. This study was utilized a non equivalent control group pre-post test design. Method: The subjects were 36 nurses in total; 18 in experimental group and 18 in control group. The data were collected from March to August, 2008. For the experimental group, 8 hour-long lectures on stress management and LME were given for 12 weeks. For the control group, only lectures on stress management was given. Depression, anxiety, perceived stress, and heart rate variability were measured on the subjects in both groups as pre- and post tests. The data were analyzed by Kolmogrov-Smirov test and P-P plot, t-test and $x^2-test$ using the SPSS program. Results: As proposed in the hypothesis, the subjects in the experimental group experienced less depression (t=2.286, p=.029), less anxiety (t=3.319, p=.002) and less perceived stress(t=2.862, p=.007) than those in the control group. Conclusion: The LME is considered an effective exercise to improve depression, anxiety, and to lessen stress for the nurses. The LME program has potential to be one of the effective stress management interventions for nurses in the future.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.167-170
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• 1989

• Architectural research
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• v.7 no.1
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• pp.11-18
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• 2005

In today's building industry the emphasis has been geared more towards construction, thus building maintenance and life cycle have been neglected until now. A direct result of this neglect is the rapid aging of building, which leads to more cost-effective decision making methods for the prolongation of building life span. The following study is conducted in the area of Daegu and Seoul in order to develop the estimation analysis method of the annual operation cost of the Korean high-rise condominiums for the cost-effective decision making support through mathematical and statistical analyses including the present value and standardized measurement corrections. Based on the assumption that the life expectancy of the high rise condominium is 50 years, initial cost is ￦421,212/$m^2$, and a total sum of yearly operation cost during life expectancy is ￦2,154,499//$m^2$), yearly accumulated operation cost is shown as below: $AOC=0.7097t^4-38.803t^3+806.95t^2+11045t-496.52$ ($R^2=0.98$) (Here, AOC = Accumulated Operation Cost, t = given years)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.715-716
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• 2013

• Journal of IKEEE
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• v.23 no.4
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• pp.1343-1352
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• 2019

To manage the Internet of Things(IoT) Network, which consists of a large number of various devices, a secure and automatic method of strengthening the IoT network is being proposed. Blockchain has a 'smart contract' element of autonomous execution method, which is emerging as a way to not only exchange data quickly without mediators but also securely and automatically manage processes between IoT devices. In this paper, we implement a prototype of the entire IoT device management system based on the EOSIO with DPoS(Distributed Proof of Stake)-based blockchain structure, proposed as a prior study, including the user application DApp(Decentralized Application) and the actual IoT devices (Raspberry Pi-based device, and smart lamp) that interact with the blockchain platform. We analyze the benefits of the system and measure the time overhead to show the feasibility of the system.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.4
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• pp.349-354
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• 2015

This paper presents the stability conditions of the Takagi-Sugeno (T-S) fuzzy sampled-data filter. The error system between the T-S fuzzy system and fuzzy filter is presented. In the sense of the Lyapunov stability analysis, the stability conditions are given, which can be represented in terms of linear matrix inequalities (LMIs). The proposed stability conditions utilize the different approach from the conventional methods, and have better performance than that of the conventional ones. The simulation example is given to show the effectiveness of the proposed method.