• Journal of the Korea Concrete Institute
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• v.28 no.4
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• pp.395-405
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• 2016

The thermal and mechanical properties of fiber-reinforced mortars for thermal energy storage were investigated in this paper. The effect of the combination of different cementitious composite on the thermal and mechanical characteristics of fiber-reinforced mortars was investigated. Experiments were performed to measure mechanical properties including compressive strength before and after thermal cycling and split tensile strength, and to measure thermal properties including thermal conductivity and specific heat. The results showed that the residual compressive strength of mixtures with OPC and graphite was greatest among the mixtures. Thermal conductivity of mixtures with alumina cement was greater than that of mixtures with OPC, indicating favor of alumina cement for charging and discharging in thermal energy storage system. The addition of zirconium into alumina cement increased specific heat of mixtures. Test results of this study could be used to provide information of material properties for thermal energy storage concrete.

• The KSFM Journal of Fluid Machinery
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• v.17 no.6
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• pp.104-108
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• 2014

The recent Fukushima nuclear power plant accidents shows that the core make up at high RCS pressure condition is very important to prevent core melting. The core make up flow at high pressure condition should be driven by gravity force or passive forces because the AC-powered safety features are not available during a Station Black Out (SBO) accident. The reactor Coolant System (RCS) mass inventory is continuously decreased by releasing steam through the pressurizer safety valves after reactor trip during a SBO accident. The core will be melted down within 2~3 hours without core make up action by active or passive mode. In the new design concept of a Hybrid Safety Injection Tank (Hybrid SIT) both for low and high RCS pressure conditions, the low pressure nitrogen gas serves as a charging pressure for a LBLOCA injection mode, while the PZR high pressure steam provides an equalizing pressure for a high pressure injection mode such as a SBO accident. After the pressure equalizing process by battery driven initiation valve at a high pressure SBO condition, the Hybrid SIT injection water will be passively injected into the reactor downcomer by gravity head. The SBO simulation by MARS code show that the core makeup injection flow through the Hybrid SIT continued up to the SIT empty condition, and the core heatup is delayed as much.

• Journal of Hydrogen and New Energy
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• v.26 no.4
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• pp.324-330
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• 2015

The electrolyte flow rates of vanadium redox flow battery play very important role in terms of ion transfer to electrolyte, kinetics and pump efficiency in system. In this paper a vanadium redox flow battery single cell was tested to suggest the optimization criteria of electrolyte flow rates on the efficiencies. The compared electrolyte circulation flow rates in this experimental work were 15, 30 and 45 mL/min. The charge/discharge characteristics of the flow rate of 30 mL/min was the best out of all flow rates in terms of charging and discharging time. The current efficiencies, voltage efficiencies and energy efficiencies at the flow rate of 30 mL/min were the best. The IR losses obtained at thd current density of $40mA/cm^2$, at the flow rates of 15, 30 and 45 mL/min were 0.085 V, 0.042 V and 0.115 V, respectively. The charge efficiencies at the current density of $40mA/cm^2$ were 96.42%, 96.45% and 96.29% for the electrolyte flow rates of 15, 30 and 45 mL/min, respectively. The voltge efficiencies at the current density of $40mA/cm^2$ were 77.34%, 80.62% and 76.10% for the electrolyte flow rates of 15, 30 and 45 mL/min, respectively. Finally, the energy efficiencies at the current density of $40mA/cm^2$ were 74.57%, 77.76% and 73.27% for the electrolyte flow rates of 15, 30 and 45 mL/min, respectively. The optimum flow rates of electrolytes were 20 mL/min in most of operating variables of vanadium redox flow battery.

• Journal of Korean Library and Information Science Society
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• v.29
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• pp.171-212
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• 1998

In this study, the concept, developments and the present situations of an electronic document delivery services, projects and systems are examined. Also the implications of an electronic document delivery services in the library and the future of the services are studied. Some conclusions and a few suggestions derived from the study are as follows : (1) An electronic document delivery services, one of the most innovative methods for delivering the needed materials to a researcher is now being incorporated into an important part of today's information industries. (2) The technological developments have made it possible to deliver nearly all the document formats electronically, and can make the shortest turnaround time to be 30minutes. The technology has also made it possible to develop user-friendly document delivery services by providing the various methods of requesting of, delivering of and charging for the materials. (3) Different types of institutions have made researches, tests, developments and implementation of an electronic document delivery techniques with different features. (4) The issues of copyrights and standards involved in an electronic document delivery still remain as the problems to be solved. (5) The increase and development of patron-initiated document delivery services have and will have some impacts on the library services with the possibility to pass by the librarians intermediation, but to deliver the materials directly to the end-users. (6) The library could take the outside electronic document delivery services as an opportunity. Accordingly, in order to incorporate this services in the interlibrary loan, collection development and other library services, the library should establish appropriate policies, guidelines and management strategies related to the operations. (7) In order to maximize the use of the electronic document delivery services, the library should provide an appropriate education for the librarian and users to have knowledge and skills on the changing techniques of the electronic document delivery and on the various features as well as changing mechanisms by each system and service.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.262.1-262.1
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• 2014

Lipid peroxidation induces functional deterioration of cell membrane and induces cell death in extreme cases. These phenomena are known to be related generally to the change of physical properties of lipid membrane such as decreased lipid order or increased water penetration. Even though the electric property of lipid membrane is important, there has been no report about the change of electric properties after lipid peroxidation. Herein, we demonstrate the molecular energy band change in red blood cell membrane through peroxidation by air-based atmospheric pressure DBD plasma treatment. Ion-induced secondary electron emission coefficient (${\gamma}$ value) was measured by using home-made gamma-focused ion beam (${\gamma}$-FIB) system and electron energy band was calculated based on the quantum mechanical Auger neutralization theory. The oxidized lipids showed higher gamma values and lower electron work functions, which implies the change of surface charging or electrical conductance. This result suggests that modified electrical properties should play a role in cell signaling under oxidative stress.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.2
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• pp.89-96
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• 2014

The repository for the disposal of LILW which is generated from nuclear power plants and industries is expected to be completed in 2014. For the disposal of LILW, it is important to secure a disposal facility itself, but it is also very important to establish a reasonable charging system which all shareholders are satisfied with. Korea's disposal fee for LILW is higher than other countries' fee, which is a burden to waste generators as well as the waste management organization. The partial reason for the high disposal fee is put on the high social and construction cost when compared with other countries. However the major reason is put on the excessive borrowing cost that is used for the construction of the LILW disposal facility. In this study, we proposed the way to reduce the excessive borrowing cost for sustainable project managements of LILW disposal by analyzing a cost structure.

• Solar Energy
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• v.19 no.3
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• pp.23-28
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• 1999

The thermal performance of storage brick, containing microencapsulated PCM(phase change material), was investigated for utilization as a floor heating system. Sodium acetate trihydrate($CH_3COONa{\cdot}3H_2O$) was selected for the PCM and was encapsulated. The thermal storage brick was manufactured with mixing cement mortar having 10%, 20% PCM contents, respectively. Four different flow rates and three different cooling temperatures was used in this work for analyzing the heat charging and discharging characteristics of the thermal storage brick. The result showed that cycle time was shortened as the PCM content was increased and as the mass flow rate was increased. The same effect was obtained when the cooling temperature was decreased. For each thermal storage brick the overall heat transfer coefficient(U-value) was constant for a 0% brick, but was increased with time for the bricks containing microencapsulated PCM.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.6
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• pp.1043-1048
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• 2017

Since year 2016, in Korea, the police department started to use drones to patrol violated vehicles on the highway area. They monitor vehicle drivers who use side ways on the highway during traffic congested hours of the season, drunken drivers, or violent drivers. They use the 'Spot Mobility' method which floats the drones for 30 minute period. However, this method is inefficient since it requires manually charging batteries, gathering data, and operate drones with many numbers of policeman. Therefore, in this paper, for the efficient patrol in this purpose, I have suggested an effectively manageable network system consists of many drones as the wireless network nodes and with small numbers of policeman in a wide highway area. To accomplish this, the two topologies of effective drone patrol network systems are designed and simulated in OPNET simulator for performance evaluation.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.2
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• pp.357-362
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• 2020

The TMFT, a sub-system of TINC, provides voice calls, data transmission and reception, and multimedia services to individual users. At the time of development in 2011, the power circuit of the TMFT was designed to electrical power supply to each device via a charger IC. However, the newly improved power supply circuit allows power to be supplied to each device through the PMIC without configuring the charger IC separately. In this paper, the power circuit design structure of TMFT applied in the development stage and the improved power circuit design structure were compared. And we verified through experiments whether the improved power circuit can be applied to TMFT. The experimental method was verified by directly comparing the current consumption test, charge time comparison test, and rising temperature test during charging each of before and after improvement terminals.

• Journal of Internet of Things and Convergence
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• v.6 no.2
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• pp.51-56
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• 2020

In this paper, we developed a mobile new media solution that enables e-commerce shopping mall operators, band operators, and YouTube creators to create synergies in online and offline promotion by posting related video contents on the media in addition to their own videos. By providing videos in the field of the platform without directly searching for them, it is possible to provide users with a new type of marketing means that can promote their platform while providing interest and information. Prospective creators at home and abroad who produce video can upload their own video in addition to YouTube and afreeca TV, such as the open market for video, and use independent and free charging systems to manage independent customer relationship management(CRM), self-branding, and content management. It will be possible to utilize mobile-based new media equipped with a system.