• Journal of the Korean Professional Engineers Association
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• v.44 no.1
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• pp.48-52
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• 2011

The KEPCO Research Institute has developed Molten Carbonate Fuel Cell(MCFC) since 1993. Recently, an 125-kW MCFC system was operated at Boryeong thermal power plant, Korea from December, 2009 to March, 2010, This system is composed of an 125-kW stack, mechanical balance of plant (MBOP), and Power Conditioning System. The stack has 200 unit cells of which effective area is 10,000 cm2. Especially, MBOP is mainly made up of ejector and catalytic combustor which help this system to be supplied with cathode inlet gas using anode tail gas and fresh air. After the pretreatment of this system was performed for about 20 days, initial load operation was performed at January. 2010. Moreover, this system had been operated for 3,270 hours.

• Journal of the Korean Society for Railway
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• v.9 no.1 s.32
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• pp.18-22
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• 2006

The dynamic characteristics of the current collection system are investigated by conducting a test run in which signals from accelerometers and load cells attached to the various parts of the pantograph are analyzed in both the time and frequency domains. The dynamic characteristics of the current collection system are found to be strongly influenced by the train speed; the fluctuation in the pantograph motion increases in direct proportion to the train speed. There exist two major fequency components in the pantograph motion related to the current collection, a speed-dependent component arising from the train traversing a span of the catenary, and a speed-independent component related to the pantograph resonant frequency. The train acceleration is also found to exert strong influence on the current collection system characteristics. The effect of the train motion is found to be stronger on the speed-dependent frequency component than on the speed-independent one.

• Journal of Industrial Technology
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• v.32 no.A
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• pp.29-33
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• 2012

We demonstrated the viability of fully microfabricating SWCNT(single-wall carbon nanotube) film strain sensors for force and weight sensing. Our spray-deposited SWCNT film strain sensors showed good linearity over a range from 0 to 400 microstrain, and much higher sensitivity compared to commercial metal foil-type gauges. The number of grids and the thickness of the SWCNT film were found to have a significant effect on the strain sensing properties of the SWCNT film gauges. A strain sensing methode for the CNT-based strain gauges was also investigated using a binocular type beam load cells. Preliminary results indicate that the microfabrication method shown here is promising for developing a commercial strain gauge using a spray-coated SWCNT thin film. In the near future, various studies will be performed to further enhance the properties of the spray-coated SWCNT film strain sensors.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3081-3083
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• 2000

Fuel cell/battery hybrid power systems were studied to develop high efficient zero-emission fuel cell electric vehicles, Fuel cells were used as an auxiliary energy source and batteries were used as a transient power source. The fuel cell system is used to supply the average power demand. Dynamic response of the hybrid systems was simulated using PSPICE program and also tested experimentally, The results can be used to design the interface module and to determine the power requirement between the fuel cell unit and the battery pack.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.584-589
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• 2008

It is known that slab thermal storage which uses concrete slab as thermal material is effective in the load leveling and using the nighttime electric power. The temperature distribution is not constant in plenum in thermal storage time by beams, ducts such as several factor. It is considered that this fact will effect on efficiency of thermal storage and indoor thermal environment. The purpose of this paper is to examine the thermal environment inside plenum. A macro model was made for the analysis of indoor thermal environment as the first step. The flow rate distribution and temperature distribution of object room model was examined by use of basic equations such as airflow by the pressure difference between unit cells, heat flow by air and heat transfer.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.04a
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• pp.106-113
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• 1997

Until now, the evaluation of prestressing force during the survice state has received limited attention. Only initial prestressing force is estimated by reading the pressure values of a hydraulic jack or by observing the initial elongation of tendons. In this study, the initial losses and time dependent losses of prestressing force have been monitored by installing 12 vibrating wire-type load cells at the part of P.C. box bridge of Gangbyun Riverside Highway. Also comparative study was made for measured prestressing losses and estimated values. 2-dimensional analysis was performed to see the trend of prestressing losses, and the results was compared with measured ones.

• International Journal of Safety
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• v.5 no.2
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• pp.1-5
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• 2006

A data acquisition and processing system for measuring the current collection signals of the Korean High-speed Railway is developed. The current collection system is composed of a pantograph and the overhead catenary that supplies electrical power to the train through the pantograph. The system simultaneously measures the signals generated at the interface between the catenary and the pantograph through the accelerometers, load cells and strain gauges placed at various locations. The on-track test data are processed to evaluate the current collection reliability. The fiequency analysis of the signals reveals the presence of several structural vibration modes in the pantograph, as well as the components arising from the periodicity in the structure of the catenary and pantograph at the interface. The feasibility of predicting the contact performance from the measured signals is also demonstrated.

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.2
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• pp.1-8
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• 2006

In this paper, we propose a distance-based location registration scheme and evaluate it's performance in a mobility model. We compare performance of the distance-based registration scheme to that of zone-based registration scheme at the mobility model. Numerical results show that the registration load of the distance-based registration with call arrival is similar to that of the zone-based registration, and is equally distributed to all cells in a location area. So the proposed scheme can be effectively used in the limited radio resources.

• Structural Engineering and Mechanics
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• v.59 no.5
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• pp.901-920
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• 2016

MeshFree methods have become popular owing to the ease with which high stress gradients can be identified and node density distribution can be reformulated to accomplish faster convergence. This paper presents a strategy for nodal density refinement with strain energy as basis in Element-Free Galerkin MeshFree technique. Two popular flat plate problems are considered for the demonstration of the proposed strategies. Issue of integration errors introduced during nodal density refinement have been addressed by suggesting integration cell refinement. High stress effects around two symmetrical semi-circular notches under in-plane axial load have been addressed in the first problem. The second considers crack propagation under mode I and mode II fracture loading by the way of introducing high stress intensity through line crack. The computational efficacy of the adaptive refinement strategies proposed has been highlighted.

• International Journal of Computer Science & Network Security
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• v.24 no.6
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• pp.171-179
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• 2024

Decentralized energy production without greenhouse gas emissions from renewable energy sources despite their advantage and environmental impact suffers from the problem of intermittent and fluctuating supply depending on weather conditions. To overcome this problem, energy storage is essential to enable reliable and continuous supply of the load. Hydrogen is one of the most promising energy storage solutions because it is easily transportable and can be used as fuel or as a raw material for the production of other chemicals.In this article, we will focus on hydrogen energy storage techniques using photovoltaic systems. We will review the different types of hydrogen storage structuresfor several applications, including residential and commercial buildings, as well as industry and transportation (electric vehicles using PEFMC fuel cells).