• Transactions on Electrical and Electronic Materials
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• v.17 no.4
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• pp.183-188
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• 2016

This paper presents the design and characterization of wide band ohmic microswitch with an actuation voltage as low as 20~25 V, and a restoring force of 14.1 μN. The design of the proposed switch is primarily composed of an electrostatic actuator, bridge membrane, cantilever (beam) and coplanar waveguide, suspended over the substrate. The analysis shows an insertion loss of −0.002 dB at 1GHz and remains as low as −0.35 dB, even at 100 GHz. The isolation loss of the switch is sustained at −21.09 dB at 100GHz, with a peak value of −99.58 dB at 1 GHz and up-state capacitance of 4 fF. To our knowledge, this is the first demonstration of a series contact switch, which works over a wide bandwidth (DC-100 GHz) and with such a high and sustained isolation, even at high frequencies and with an excellent figure of merit (f_c=1/2.pi.Ron.Cu= 39.7 THz).

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.10
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• pp.645-653
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• 2008

Spiral-jacketed thermal storage tanks can greatly simplify solar heating systems while maintaining the thermal performance at a similar level as conventional systems with an external heat exchanger. Proper design of the spiral-jacket flow path is essential to make the most of solar energy, and thus to maximize the thermal performance. In the present work, computational fluid dynamics (CFD) analysis was carried out for a spiral-jacketed storage tank installed in a solar heating demonstration system. The results of the CFD analysis showed a good agreement with experimentally determined thermal performance indices such as the acquired heat, collector efficiency, and mixed temperature in the storage tank. This verified CFD modelling approach can be a useful design tool in optimizing the shape of spiral-jacket flow path and the flow rate of circulating fluid for better performance.

• Nuclear Engineering and Technology
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• v.41 no.9
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• pp.1171-1180
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• 2009

The internal core baffle structure of a French Pressurized Water Reactor (PWR) consists of a collection of baffles and formers that are attached to the barrel. The connections are done thanks to a large number of bolts (about 1500). After inspection, some of the bolts have been found cracked. This has been attributed to the Irradiation Assisted Stress Corrosion Cracking (IASCC). The $Electricit\acute{e}$ De France (EDF) has set up a research program to gain better knowledge of the temperature distribution, which may affect the bolts and the whole structure. The temperature distribution in the structure was calculated thanks to the thermal code SYRTHES that used a finite element approach. The heat transfer between the by-pass flow inside the cavities of the core baffle and the structure was accounted for thanks to a strong thermal coupling between the thermal code SYRTHES and the CFD code named Code_Saturne. The results for the CP0 plant design show that both the high temperature and strong temperature gradients could potentially induce mechanical stresses. The CPY design, where each bolt is individually cooled, had led to a reduction of temperatures inside the structures. A new parallel version of SYRTHES, for calculations on very large meshes and based on MPI, has been developed. A demonstration test on the complete structure that has led to about 1.1 billion linear tetraedra has been calculated on 2048 processors of the EDF Blue Gene computer.

• Journal of Korean Academy of Nursing
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• v.49 no.5
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• pp.586-600
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• 2019

Purpose: This study aimed to develop a web-based cost management program for visiting nursing centers (CMP-VNC), using time-driven activity-based costing (TD-ABC), and to analyze effects of the program. Methods: The CMP-VNC was developed using the combined prototyping approach and system developing life cycle method following four stages: need analysis with comprehensive literature reviews and focus group interviews, design and development of program algorithm, evaluation of the developed program validity using experts and users group, and application and effects analysis. The non-equivalent control group pretest-posttest design was used to analyze the effects of the program. The program demonstration was conducted for four weeks with 60 visiting nurses in 35 visiting centers. Results: The web-based program was developed. It has five interfaces with basic and special functions using TD-ABC, namely, input, visiting nursing activity, visiting nursing activity cost, cost efficiency, and cost calculation report. The experimental group showed significantly higher cost perception and cost confidence than control group. Conclusion: We found that the CMP-VNC can be an effective tool to increase visiting nurses' competency of costing and enhance efficiencies of visiting nursing centers.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.48-59
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• 2020

A traditional propeller can easily become entangled with floating objects while operating. In this paper, we present a newly developed Electromagnetic-valve-control-based Water-jet Propulsion System (ECWPS) for an unmanned surface cleaning vessel that can be flexibly controlled via a Micro Control Unit (MCU). The double-structure was adapted to the unmanned surface cleaning vessel for floating-collection missions. Computational Fluid Dynamics (CFD) software for operating effect simulation was also used to reveal the working principle of the ECWPS under different conditions. Neglecting the assembly technique, the design level, controlling strategy, and maneuvering performance of the ECWPS reached unprecedented levels. The ECWPS mainly consists of an Electromagnetic-valve Array (EA), pipeline network, control system, and water-jet source. Both CFD analyses and experimental results show that the hydraulic characteristic of the ECWPS was predicted reasonably, which has enormous practical value and development prospects.

• The Journal of Information Systems
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• v.30 no.2
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• pp.243-259
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• 2021

Purpose The beginning of innovation and creation, Haenggung-dong, Paldal-gu, Suwon-si: Suwon Hwaseong Fortress, which began in 1794 by King Jeongjo in accordance with the spirit of Beopgochangsin, mobilized the abilities of traditional techniques, new science and technology, and artists New starting point for urban innovation in Suwon: Based on 5G technology possessed by leading companies in the global ICT industry in Hwaseong (Haenggung-dong), a product of cutting-edge evidence, solve various urban problems through public, private, industrial and academic governance, and a new business model It aims to reorganize into the space where this is created. Design/methodology/approach The New 1794 Project is a 2019 demonstration project requested by the Ministry of Land, Infrastructure and Transport for "Suwon Smart City Challenge Project: Haenggung-dong, Paldal-gu, Suwon-si," developed by the Dankook University SW Design Convergence Center, and the main project from 2020 to 2022. The smart city project strategy should be implemented based on partnerships with multiple stakeholders, and the bottom-up approach and the traditional top-down must be able to coexist. Therefore, the smart city solution applied a horizontal governance method. Findings In this study, the definition of the New 1794 Project, which is the key to defining smart cities in relation to all analyzed aspects, was developed.

• The Journal of Information Systems
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• v.31 no.4
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• pp.101-121
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• 2022

Purpose This study aims to introduce a Smart-Platform for solving numerous problems in urban cities and improving citizens' convenience. This Smart-Platform is achieved by studying the City Data Hub technology to build and spread a Smart City Data Hub . Design/methodology/approach In this study, we analyzed the functions in detail and interlocking flows specific to the published City Data Hub module and designed a Smart-Platform with additional UI-based functions to improve users' convenience based on our previous experience. Findings The City Data Hub will provide a modular data hub platform functionality for application by different stakeholders. However, further research on detailed functionality and experience in interworking legacy systems will be required to apply the platform realistically. Therefore, we judged that this Smart-Platform, which supplements the City Data Hub with additional functions, would be useful for utilizing the City Data Hub in the future. Through the demonstration of the platform designed, it is also necessary to explore the direction of continuous development for the future.

• Transactions on Electrical and Electronic Materials
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• v.17 no.2
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• pp.92-97
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• 2016

This paper presents design and simulation of wide band RF microswitch that uses electrostatic actuation for its operation. RF MEMS devices exhibit superior high frequency performance in comparison to conventional devices. Similar techniques that are used in Very Large Scale Integration (VLSI) can be employed to design and fabricate MEMS devices and traditional batch-processing methods can be used for its manufacturing. The proposed switch presents a novel design approach to handle reliability concerns in MEMS switches like dielectric charging effect, micro welding and stiction. The shape has been optimized at actuation voltage of 14-16 V. The switch has an improved restoring force of 20.8 μN. The design of the proposed switch is very elemental and primarily composed of electrostatic actuator, a bridge membrane and coplanar waveguide which are suspended over the substrate. The simple design of the switch makes it easy for fabrication. Typical insertion and isolation of the switch at 1 GHz is -0.03 dB and -71 dB and at 85 GHz it is -0.24 dB and -29.8 dB respectively. The isolation remains more than - 20 db even after 120 GHz. To our knowledge this is the first demonstration of a metal contact switch that shows such a high and sustained isolation and performance at W-band frequencies with an excellent figure-of merit (fc=1/2.pi.Ron.Cu =1,900 GHz). This figure of merit is significantly greater than electronic switching devices. The switch would find extensive application in wideband operations and areas where reliability is a major concern.

• Nuclear Engineering and Technology
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• v.41 no.4
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• pp.427-446
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• 2009

In order to meet the increasing demand for electricity, Korea has to rely on nuclear energy due to its poor natural resources. In order for nuclear energy to be expanded in its utilization, issues with uranium supply and waste management issues have to be addressed. Fast reactor system is one of the most promising options for electricity generation with its efficient utilization of uranium resources and reduction of radioactive waste, thus contributing to sustainable development. The Korea Atomic Energy Research Institute (KAERI) has been performing R&Ds on Sodium-cooled Fast Reactors (SFRs) under the national nuclear R&D program. Based on the experiences gained from the development of KALIMER conceptual designs of a pool-type U-TRU-10%Zr metal fuel loaded reactor, KAERI is currently developing Advanced SFR design concepts that can better meet the Generation IV technology goals. This also includes developing, Advanced SFR technologies necessary for its commercialization and basic key technologies, aiming at the conceptual design of an Advanced SFR by 2011. KAERI is making R&D efforts to develop advanced design concepts including a passive decay heat removal system and a supercritical $CO_2$ Brayton cycle energy conversion system, as well as developing design methodologies, computational tools, and sodium technology. The long-term Advanced SFR development plan will be carried out toward the construction of an Advanced SFR demonstration plant by 2028.

• Journal of Radiation Protection and Research
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• v.47 no.1
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• pp.50-57
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• 2022

Background: There are several proton therapy facilities in operation or planned in Taiwan, and these facilities are anticipated to not only treat cancer but also provide beam services to the industry or academia. The simplified approach based on the Monte Carlo-based data sets (source terms and attenuation lengths) with the point-source line-of-sight approximation is friendly in the design stage of the proton therapy facilities because it is intuitive and easy to use. The purpose of this study is to expand the Monte Carlo-based data sets to allow the simplified approach to cover the application of proton beams more widely. Materials and Methods: In this work, the MCNP6 Monte Carlo code was used in three simulations to achieve the purpose, including the neutron yield calculation, Monte Carlo-based data sets generation, and dose assessment in simple cases to demonstrate the effectiveness of the generated data sets. Results and Discussion: The consistent comparison of the simplified approach and Monte Carlo simulation results show the effectiveness and advantage of applying the data set to a quick shielding design and conservative dose assessment for proton therapy facilities. Conclusion: This study has expanded the existing Monte Carlo-based data set to allow the simplified approach method to be used for dose assessment or shielding design for beam services in proton therapy facilities. It should be noted that the default model of the MCNP6 is no longer the Bertini model but the CEM (cascade-exciton model), therefore, the results of the simplified approach will be more conservative when it was used to do the double confirmation of the final shielding design.