• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.27-30
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• 2003

This paper describes two novel current fed high frequency resonant inverter can be used as the power supp]y for wax-sealing. This two topology can be obtained higher output frequency than switching frequency by composing modified unit inverter based on conventional half-bridge serial resonant inverter in parallel with input power source. also, By using time-sharing gate control method, this proposed inverter can not only realize the output control of dependence irrespective of the switching frequency using phase-shift but also reduce switching loss because it has ZVS function. Simulation results through the Pspice have demonstrated the feasibility of the proposed inverter. This proposed inverter will be able to be practically used as a power supply in various fields as induction heating applications, DC-DC converter etc.

• Journal of Digital Convergence
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• v.12 no.6
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• pp.145-154
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• 2014

ADHD is a neuro-developmental disorder that begins in childhood, yet may continue into adulthood. Although 3 to 4 percent of adults are affected by ADHD, but only a small proportion of adults ever receive a formal diagnosis and treatment. The core symptoms of ADHD frequently lead to significant academic difficulties that often result in the students' teacher being the first to suspect the disorder. In order for school teachers to effectively deal with ADHD students in school classrooms, they need to have positive attitude toward ADHD students. This study presents a list of ADHD-related web sites which provide educational contents and support for school teachers, and provides the discussions about the current status and the roles of those web sites.

• Journal of Power Electronics
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• v.9 no.2
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• pp.133-145
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• 2009

In this paper a modular high performance MV-to-LV rectifier based on a cascaded H-bridge rectifier is presented. The proposed rectifier can directly connect to the medium voltage levels and provide a low-voltage and highly-stable DC interface with the consumer applications. The input stage eliminates the necessity for heavy and bulky step-down transformers. It corrects the input power factor and maintains the voltage balance among the individual DC buses. The second stage includes the high frequency parallel-output DC/DC converters which prepares the galvanic isolation, regulates the output voltage, and attenuates the low frequency voltage ripple ($2f_{line}$) generated by the first stage. The parallel-output converters can work in interleaving mode and the active load-current sharing technique is utilized to balance the load power among them. The detailed analysis for modeling and control of the proposed structure is presented. The validity and performance of the proposed topology is verified by simulation and experimental results.

• Journal of Information Management
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• v.34 no.4
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• pp.19-42
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• 2003

Reference services have taken a central place in library and information services. But current digital libraries focus more on access to digital information, and hardly lay emphasis on the service aspects. This paper looks at the current state of research in reference services in digital libraries. It first analyses some representative definitions of digital reference services. It then provides a brief overview of the various online reference and information services currently available on the Web. The paper also reviews the types of the digital reference service in major 'Aska' service sites. Finally, the paper proposes new digital reference service model that specifically bases on the sharing of the human and information.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.478-488
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• 2014

Torque pulsation mechanism and highly nonlinear magnetic characterization of switched reluctance motors(SRM) lead to unfavorable torque ripple and limit the variety of applications in industry. In this paper, a modification method proposed for torque ripple minimization of SRM based on conventional torque sharing functions(TSF) to improve maximum speed of torque ripple-free operation considering converter limitations. Due to increasing phase inductance in outgoing phase during the commutation region, reference current tracking can be deteriorated especially when the speed increased. Moreover, phase torque production in incoming phase may not be reached to the reference value near the turn-on angle in which the incremental inductance would be dramatically decreased. Torque error for outgoing phase can cause increasing the resultant motor torque while it would be negative for incoming phase and yields reducing the motor torque. In this paper, a modification method is proposed in which phase torque tracking error for each phase under the commutation added to the other phase so that the resultant torque remained in constant level. This yields to extend constant torque region and reduce peak phase current when the speed increased. Simulation and experimental results for four phase 4 KW, 8/6 SRM validate the effectiveness of the proposed scheme.

• Archives of Plastic Surgery
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• v.50 no.4
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• pp.443-444
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• 2023

Point-of-care photography and photo sharing optimize patient outcomes and facilitate remote consultation imperative for resident surgeons. This literature review and external pilot survey study highlight the risks associated with current practices concerning patient privacy and biometric security. In a survey of 30 plastic surgeon residents and attendings, we found that the majority took photos of patients with their iPhones and shared them with colleagues via Apple iMessage. These findings corroborate previous reports and highlight a lack of physician user acceptance of secure photo-sharing platforms. Finally, we frame a successful example from the literature in the context of a postulated framework for institutional change. Prioritizing the privacy and safety of patients requires a strategic approach that preserves the ease and frequency of use of current practices.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.516-524
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• 2022

The construction industry is considered the most hazardous industry globally. Therefore, safety education is crucial for raising the safety awareness of construction workers working at construction sites and creating a safe working environment. However, the current safety education method and tools cannot provide trainees with realistic and practical experiences that might help better safety awareness in practice. A metaverse, a real-time network of 3D virtual worlds focused on social connection, was created for more interactive communication, collaboration, and coordination between users. Several previous studies have noted that the metaverse has excellent potential for improved safety education performance, but its required functions and practical applications have not been thoroughly researched. In order to fill the research gap, this paper reviewed the potential benefits of a metaverse based on the current research and suggested its application for safety education purposes. This paper scrutinized the metaverse's key functions, particularly its information and knowledge sharing function and reality capture function. Then, the authors created a metaverse prototype based on the two key functions described above. The main contribution of this paper is reviewing the potential benefits of a metaverse for safety education. A realistic and feasible metaverse platform should be developed in future studies, and its impact on safety education should be quantitatively verified.

• Aerospace Engineering and Technology
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• v.3 no.2
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• pp.11-19
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• 2004

A software-controlled unregulated bus system in which the main bus is directly connected to a battery and the duty-ratio for PWM switch is controlled by the on-board satellite software, is usually used for LEO satellites. This paper proposes a new power-stage circuit that can be available for modularization of a power regulator which is used at the software-controlled unregulated bus system satellite. And we analyze the proposed power-stage operation according to its operating modes and verify it by performing software simulation and hardware experiment using prototype. We construct a parallel-module converter which is composed of the proposed power-stage and perform experiment to verify modular characteristics of the proposed power-stage. Finally, we verify the usefulness of the proposed power-stage by comparing above results with those of a parallel-module converter made of conventional power-stage.

• Journal of Korea Society of Digital Industry and Information Management
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• v.14 no.3
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• pp.103-113
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• 2018

The purpose of this study supports the establishment of national e-learning policy by analyzing e-learning status and current status of higher education. Enhance the competitiveness of higher education through sharing information between universities. And to improve e-learning quality management. We surveyed the current status of e-learning in 341 universities and questionnaires about e-learning content, e-learning application form, e-learning platform status was surveyed through each school's learning management system. As a result, the infrastructure of e-learning, the rate of platforms secured, and the contents are increasing gradually each year; however, still, not all students can receive the services equally. Dedicated servers and learning management systems were secured by more than 70% of general universities. In the current development status of e-learning content, multimedia, animation, and text forms are gradually decreasing, but video contents are increasing every year. Most of the online contents were used in the e-learning contents by application type, and blended learning, flipped learning, and mooc is not yet actively used since they are still in the beginning stage. Learning analysis techniques should be supported in order to easily use online learning contents such as flipped learning and mooc. We suggest that the effectiveness of e-learning should be measured and the current state of learning analysis for customized learning should be done. This study aims to contribute to the improvement of competitiveness of higher education by sharing information about e-learning among universities as a basis for improvement of e-learning policy. Future tasks are to improve the customized learning environment by adding whether the system environment for learning analysis is provided at the time of the survey.

• Journal of Korea Society of Industrial Information Systems
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• v.8 no.2
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• pp.84-91
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• 2003

KOMPSAT series use software-controlled unregulated bus system in which the main bus is directly connected to a battery and the duty-ratio for PWM switch is controlled by the on-board satellite software. This paper proposes a new power-stage circuit that can be available for modularization of the power regulator which is used at the software-controlled unregulated bus system satellite. And we analyze the proposed power-stage operation according to its operating modes and verify it by performing software simulation and hardware experiment using prototype. We construct a parallel-module converter which is composed of proposed power-stages and perform experiment to verify modular characteristics of the proposed power-stage. Finally, we verify the usefulness of the proposed power-stage by comparing above results with those of a parallel-module converter made of conventional power-stages.