• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.256-262
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• 2018

This study introduces a novel Soft Switching (SS) Pulse Width Modulated (PWM) AC-DC boost converter. In the proposed converter, the main switch is turned on with Zero Voltage Transition (ZVT) and turned off with Zero Current Transition (ZCT). The main diode is turned on with Zero Voltage Switching (ZVS) and turned off with Zero Current Switching (ZCS). The auxiliary switch is turned on and off with ZCS. All auxiliary semiconductor devices are turned on and off with SS. There is no extra current or voltage stress on the main semiconductor devices. The majority of switching energies are transferred to the output by auxiliary transformer. Thus, the current stress of auxiliary switch is significantly reduced. Besides, the proposed converter has simple structure and ease of control due to common ground. The theoretical analysis of the proposed converter is verified by a prototype with 100 kHz switching frequency and 500 W output power. Furthermore, the efficiency of the proposed converter is 98.9% at nominal output power.

• Journal of Power Electronics
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• v.2 no.2
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• pp.139-145
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• 2002

Because conventional switching converters have been usually using unbalanced circuit topologies, parasitice between the drain/collertor of an active switch and frame ground through its heat sink may generate the commom-mode conducted noise. We have proposed a balanced switching converter circuit, whitch is an effective way to reduce the commom-mode converter version of the balanced switching converter was presented and the mechanism of the commom-mode noise reduction was explained using equivalent circuits. This paper extends the concept of the balanced switch converter circuit and presents a buck-boost converter version of the blanced switching converter. The feature of common-mode niose reduction is confirmed by experimental resuits and the mechanisem of the commom-mode niose reduction is explained using equivalent circuits.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.82-85
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• 1987

Electromagnetic waves from the satellite may be utilized to direct the tracking antenna toward the satellite. We design and fabricate the feed appropriate to the monopulse tracking technique which derive angle-error information on the basis of a single pulse. The feed consists of five cavity-backed turnstile elements mounted on a common ground plane. The turnstile dipole are connected to a set of five quadrature hybrids which convert the dual linear polarization into dual circular polarization. The five feed outputs are then processed in the monopulse comparator which is constructed in microstrip for compactness.

• Nuclear Engineering and Technology
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• v.30 no.2
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• pp.83-90
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• 1998

To predict effects of seismic isolation, seismic isolation bearings were applied to the Wolsong reactor building and the analytical study was performed. For this study, the Wolsong reactor building was modeled using lumped masses and beam elements. Design Basis Earthquake with a ground acceleration of 0.2g was applied. And then, the behavior of the isolated structure was compared with that of the unisolated structure. The horizontal response acceleration at the top of the unisolated reactor building was 0.99g, while that of the isolated one was 0.14g(15% damping) and the acceleration response along the height of the structure was constant. The maximum displacement of the unisolated structure was 8.3mm, while that of the isolated structure was 66mm. The application of isolation bearings on the reactor building reduces seismic loads but increases the displacement of the structure on a large scale. Therefore, when using isolation bearings, the reactor building and BOP should be located on a common mat to cover the large displcement.

• Safety and Health at Work
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• v.13 no.3
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• pp.372-375
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• 2022

In the globalized field of safety, health, and well-being, the need to build multi-stakeholder alliances to find solutions to complex challenges is growing. This requires common ground for collaboration, as well as concepts and tools to grasp and manage the areas of interest. Over recent years, Vision Zero has awakened interest and it continues to evolve into many forms of approaches and initiatives, which provide a strategic direction and practical tools for supporting the development of safety, health, and well-being at work. Consequently, there is a need to build a shared understanding of 'zero'. This article reflects the potential of Vision Zero as a bridging concept and an approach for building multi-stakeholder collaboration. Thus, we present a multi-perspective framework of Vision Zero to support further dialoge and collaboration in joint undertakings.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.774-780
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• 2009

Simulation is becoming increasingly popular in construction for training, planning and for assessment of projects. There are, however, significant problems inherent in simulating construction which are not common to other simulations. This paper describes the development and use of computer-based game for teaching and learning of some aspects of construction project management. It is concerned with the development of a model used to simulate the construction of a rock- and clay-fill dam. It includes detailed physical modelling of the performance of individual pieces of equipment and their interaction with the ground, the geography of the project and the weather in which the equipment operates. The behaviour of all of the individual pieces of equipment when acting as fleets is also discussed. The paper also describes the modelling issues of non-technical aspects of earthmoving operations. These include environmental impact, safety, quality and risks. The problems of integrating these with the physics-based models of the equipment performance are discussed. The paper also draws on real experience of using the game in classes in three universities in different countries.

• Journal of the Daesoon Academy of Sciences
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• v.24_2
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• pp.57-82
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• 2015

Grievance resolution, gratitude and mutual beneficence are not only an essential dogma of Daesoonjinrihoe but also a major issue which Chinese Confucian scholars have been concerned about. In this context, this study compares the perspectives of grievance resolution, gratitude, mutual beneficence based on basic scriptures of Daesoonjinrihoe and ancient Chinese Confucianism. With nurture and benevolence as core thoughts, the ways of ruling the world in righteousness and proprieties have common characteristics of Daesoonjinrihoe and Confucianism. The Heavenly Way, which is rather an abstract conception, is perceived as a Confucianism ultimate ground. Because Confucianism does what is right for nurture, embracing rationality, the religious aspects are not clearly defined, it is the difference between Daesoonjinrihoe and Chinese Confucianism. In this regard, this study compares similarities and differences between the two cultures to promote mutual understanding.

• Progress in Superconductivity and Cryogenics
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• v.10 no.3
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• pp.32-35
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• 2008

A common problem in many fields of cryogenic power engineering is applying high voltage to cold parts of superconducting apparatus. In many cases, a bushing provides electrical insulation for the conductor which makes the transition from ambient temperature to the cold environment. The 60 kV class cryogenic high voltage bushing for neutral line of the 154 kV / 100MVA high temperature superconducting (HTS) transformer was described. The bushing is energized with the line-to-ground voltage between the coaxial center and outer surrounding conductors; in the axial direction, there was a temperature difference from ambient to about 77 K. For the insulation design of cryogenic bushing, electrical insulation characteristics of the GFRP were discussed in this paper.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.346-347
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• 2020

This paper presents the two combination methods for leakage current reduction in photovoltaic system PCS. The leakage current in the photovoltaic system generated from the parasitic capacitance existing between the photovoltaic system and ground relevance to common mode voltage caused by PWM switching. Firstly, Leakage current reduced by a PWM method using two carriers with 180-degree phase different. Secondly, the leakage current is more reduced by connecting LCL filter to the mid-point of DC link. This combining method is revealed in PSIM simulation with 1 uF parasitic capacitance.

• Electronics and Telecommunications Trends
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• v.39 no.4
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• pp.21-31
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• 2024

Major global powers are investing heavily in artificial intelligence (AI) and hyper-connected networks, demonstrating their crucial role in future warfare. To advance and utilize AI in national defense, it is essential to have policy support at the governmental or national level. This includes establishing a research and development infrastructure, creating a common development environment, and fostering AI expertise through education and training programs. To achieve advancements in hyper-connected networks, it is essential to establish a foundation for a robust and resilient infrastructure by comprehensively building integrated satellite, aerial, and ground networks, along with developing 5G & edge computing and low-orbit satellite communication technologies. This multi-faceted approach will ensure the successful integration of AI and hyper-connected networks, strengthening national defense and positioning nations at the forefront of technological advancements in warfare.