• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.4
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• pp.309-317
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• 2000

This paper presents the switching angle and voltage to maximize torque/efficiency and minimize torque ripple in the 4-phase 6-poles Switched Reluctance Motor(SRM). SRM drive has high saturation and nonlinear characteristics of inductance. So we cannot hard to find optimal condition by using analytic method. Therefore it is hard to find the operating the switching angle and voltage through the approximated analysis and computer simulation by using SIMULINK according to the speed and torque required by load. From the results, we can say that the optimum average voltage is determined by the load only and the speed is determined by the optimum turn-on/off angle only. And the maximum efficiency and minimum torque ripple depend on switching angle, not on voltage. And then one-chip microcontroller controls the switching angle and voltage of an asymmetrical inverter in the SRM driver. This drive method, which is expect that the driving methods, which are maximizing torque/efficiency and minimizing torque ripple, will be suitable for the electric vehicle, the industrial application and household appliances.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.2
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• pp.42-48
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• 2005

A DC-DC converter is being widely used for various household appliances and for industry applications. The DC-CC converter is powered from single battery, and the voltage is varied according to the purpose. In the vehicle, various accessories whose electric power is different are being un4 Thus, plural number of DC-DC converter should be provided, so these situations bring complicated circuits, and accordingly, higher cost. Under such backgrounds, in this paper, we propose a novel buck-boost chopper circuit with simply configuration which can supply to two or more different output loads. The propose chewer circuit can control output voltages by controlling duty ratio by using typically two switching devices, which is composed by single boost-switch and single buck-switch. The output voltage can be controlled widely. A few modified circuits developed from the fundamental circuit are represented including the general multi-load circuit. And all this merits and appropriateness was proved by computer simulation and experience.

• Journal of Korean Elementary Science Education
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• v.24 no.5
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• pp.620-626
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• 2005

In this study, we conducted a comparative study to investigate the curriculums on electricity and magnetism between in Korean and in Ontario elementary schools in Canada with respect to connectivity and difference among course materials with grades. We compared textbooks that contain the contents about electricity and magnetism, and connectivity in curriculums that were relevant to the science content system in each country. We report the following differences in the curriculums on electricity and magnetism in each country. First, it turns out that science is taught from the first grade in Ontario, while it is taught from the third grade in Korea. Second, Ontario covers electricity and magnetism only in science curriculum, while Korea covers the same topics both in the science and practical arts curriculum. Third, while the curriculum in Korea introduces 'a magnet' in the third grade, 'electricity' in the fourth and the fifth grade, and 'an electromagnet' in the sixth grade, while the curriculum in Ontario covers the concept of energy from the first grade. As the grades go up, the contents of electricity and magnetism tend to be more deepen. It also emphasizes enhancing students' ability that they can communicate what they learn about technology with others, and that they can apply their knowledge to other fields as well. Based on this study of the Ontario curriculum, we suggest that it is necessary for us to n Science curriculum from the first grade, so that the students can learn science from the early grade, without a need to run another subject, like practical arts. We also found that the Korean curriculum has an interesting structure for the young students to learn to apply their knowledge to the real life immediately, based on an idea that the topic of 'Manipulating the electric appliances' in practical arts curriculum moves to the Science.

• Journal of Intelligence and Information Systems
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• v.16 no.2
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• pp.95-108
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• 2010

In this paper, we present a hybrid neural network model for dynamic hand gesture recognition. The model consists of two modules, feature extraction module and pattern classification module. We first propose a modified CNN(convolutional Neural Network) a pattern recognition model for the feature extraction module. Then we introduce a weighted fuzzy min-max(WFMM) neural network for the pattern classification module. The data representation proposed in this research is a spatiotemporal template which is based on the motion information of the target object. To minimize the influence caused by the spatial and temporal variation of the feature points, we extend the receptive field of the CNN model to a three-dimensional structure. We discuss the learning capability of the WFMM neural networks in which the weight concept is added to represent the frequency factor in training pattern set. The model can overcome the performance degradation which may be caused by the hyperbox contraction process of conventional FMM neural networks. From the experimental results of human action recognition and dynamic hand gesture recognition for remote-control electric home appliances, the validity of the proposed models is discussed.

• Archives of design research
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• v.19 no.2 s.64
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• pp.333-342
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• 2006

Consumers have paid attention to various functions of PC's nowadays from its efficiency in the past. This study set limits to adapted computers by consumer needs for their residence facilities and ubiquitous environment in our society. The purpose of this study is to suggest high potentialities of adapted computers and it's design for materializing house ubiquitous system. It has come out from analyzing PC market. The result is that Barebone PC, a kind of set PC, could be one of the most actual way for materializing house ubiquitous system. This study suggests many potentialities of Barebone PC which invites modular system. The existing Barebone PC is a kind of semimanufactures, however the new Barebone PC in this study is a expanded concept of modular system that connected to the area of the electric home appliances. This is inspected by analyzing the relation among potentialities and impotance of set PC design and module.

• Journal of the Korea Society of Computer and Information
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• v.11 no.3
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• pp.203-211
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• 2006

Today, Internet covers a world wide range and most appliances of our life are linked to network from enterprise server to household electric appliance. Therefore, the importances of administrable framework that can grasp network state by real-time is increasing day by day. Our objective in this paper is to describe a network weather report framework that monitors network traffic and performance state to report a network situation including traffic status in real-time. We also describe a mobile agent architecture that collects state information in each network segment. The framework could inform a network manager of the network situation. Through the framework. network manager accumulates network data and increases network operating efficiency.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1183-1194
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• 2021

Traditionally, electric power systems have been known as the centralized structures, which is organized into placing customers at the end of the supply chain. However, recent decades have witnessed the emergence of distributed energy resources(:DERs) such as rooftop solar, farming PV system, small wind turbines, battery energy storage systems and smart home appliances. With the emergence of distributed energy resources, the role of distributed system operators(:DSOs) will expand. The increasing penetration of DERs could lead to a less predictable and reverse flow of power in the system, which can affect the traditional planning and operation of distribution and transmission networks. This raises the need for a change in the role of the DSOs that have conventionally planned, maintained and managed networks and supply outages. The objective of this research is to designed the future distribution operation system with multi-DERs and the proposed distribution system model is implemented by hardware-in-the-loop simulation(HILS). The test results show the normal operation domain and reduction of distribution line loss.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1223-1230
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• 2021

Recently, energy resource management is a major concern around the world. Energy management activities minimize environmental impacts of the energy production. This paper presents design and prototyping of a home electric energy monitoring system that provides residential consumers with real time information about their electricity use. The developed system is composed of an in-house sensing system and a server system. The in-home sensing system is a set of wireless smart plug which have an AC power socket, a relay to switch the socket ON/OFF, a CT sensor to sense current of load appliance and a Kmote. The Kmote is a wireless communication interface based on TinyOS. Each sensing node sends its detection signal to a home gateway via wireless link. The home gateway stores the received signals into a remote database. The server system is composed of a database server and a web server, which provides web-based monitoring system to residential consumers. We analyzed and presented energy consumption data from electrical appliances for 3 months in home. The experimental results show the promising possibilities to estimate the energy consumption patterns and the current status.

• Advances in concrete construction
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• v.14 no.2
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• pp.103-113
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• 2022

On the basis of fabrication, the utilization of nano material in numerous industrial and technological system, obtained the utmost significance in current decade. Therefore, the current investigation presents a theoretical disposition regarding the flow of electric conducting Williamson nanoliquid over a stretchable surface in the presence of the motile microorganism. The impact of thermal radiation and magnetic parameter are incorporated in the energy equation. The concentration field is modified by adding the influence of chemical reaction. Moreover, the splendid features of nanofluid are displayed by utilizing the thermophoresis and Brownian motion aspects. Compatible similarity transformation is imposed on the equations governing the problem to derive the dimensionless ordinary differential equations. The Homotopy analysis method has been implemented to find the analytic solution of the obtained differential equations. The implications of specific parameters on profiles of velocity, temperature, concentration and motile microorganism density are investigated graphically. Moreover, coefficient of skin friction, Nusselt number, Sherwood number and density of motile number are clarified in tabular forms. It is revealed that thermal radiation, thermophoresis and Brownian motion parameters are very effective for improvement of heat transfer. The reported investigation can be used in improving the heat transfer appliances and systems of solar energy.

• Biomedical Science Letters
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• v.30 no.2
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• pp.81-85
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• 2024

Among all subjects who participated in the survey in the 9th 1st year (2022), 2,448 men (44.0%) and 3,166 women (56.0%) aged 12 or older were identified to determine oral care behavior according to orthodontic treatment experience. The purpose was to provide basic data on the oral care of patients wearing orthodontic appliances. 1. When it comes to brushing teeth, brushing before going to bed was the highest. Regarding the use of oral care products, 3,965 people (69.1%) said they 'do not use dental floss', 4,064 people (73.2%) said they 'do not use interdental brushes', and 4,064 people (73.2%) said they used oral rinse. 'I don't do it' was the highest at 4,417 (77.7%), and electric toothbrushes were the highest at 'I don't do it' at 5,241 (93.6%). 2. In terms of the effect of orthodontic treatment experience on toothbrushing time, with orthodontic treatment experience, toothbrushing after breakfast was 0.598 times more likely (P<0.001), and toothbrushing after lunch was 1.482 times more likely (P<0.001). Toothbrushing after dinner was 0.805 times higher (P=0.049), and toothbrushing before going to bed was 1.794 times higher (P<0.001), which was statistically significant. 3. When having orthodontic treatment experience, dental floss was found to be used 1.434 times more often (P=0.002), interdental brushes were used 1.464 times more times (P<0.001), and oral rinses were found to be used 1.457 times more times (P=0.002), which was statistically significant.