• Journal of Power Electronics
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• v.16 no.2
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• pp.815-822
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• 2016

The efficiency of light-emitting diode (LED) devices is a significant factor that reflects the capability of these devices to convert electrical power into optical power. In this study, a method for estimating the efficiency of LED devices is proposed. An efficiency model and a heat power model are established as convenient tools for LED performance evaluation. Such models can aid in the design of LED drivers and in the reliability evaluation of LED devices. The proposed estimation method for the efficiency and heat power of LED devices is verified by experimentally testing two types of commercial LED devices.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.687-689
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• 2000

Molten Carbonate Fuel Cell (MCFC) with high electrical efficiency and low environmental effect has been developed for the commercial application of power generation fields. Recently we have built a 25 kW molten carbonate fuel cell power generation system and tested it. The MCFC system is composed of diverse peripheral units such as reformer, pre-heater, water purifier. electrical loader, gas supplier, and recycling systems. The stack itself was made of 40 cells of $6.000 cm^2$ area each. The stack showed an output of 28.6 kW power and a reliable performance at atmospheric operation. while in pressurized operation the stack showed an output 25.6 kW lower than the atmospheric operation. The reason of lower performance of pressurized operation was caused from a gas cross over shown in few cells in the stack.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.575-579
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• 2003

In this paper, we describe a Duplex Power Controller for Control Rod Control System(CRCS). A Duplex Power Controller has the various functions for the reliable operations of Control Rod Drive Mechanism(CRDM). Also we have implemented the diverse functions by utilizing the developed Duplex Power Controller. Due to the developed Duplex Power Controller, we are assured that the commercial operation by this system be made before long.

• Journal of the Korean Solar Energy Society
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• v.28 no.5
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• pp.72-77
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• 2008

The purpose of this paper is to explain the real characteristics of generation system of large scale power system of high voltage the grid connected PV power system for electricity industry. Main system is made up PCS in the class 150kVA. and we studied commercial operation in Korea-Western Power Company,(Tae-An headquarter) with the capacity of module is 122.5 $kW_p$. On the average, power plant utilities' utilization is 12.71 percent and consumption rate is 6.66 percent. We operated normally since 25th, August 2005 without any other problems.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.3
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• pp.245-252
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• 2010

For the purpose of evaluating to remove elemental mercury using SCR (Selective Catalytic Reduction) catalysts, the result of the concentration variation of elemental mercury in lab experiment and field measurement was compared. The effect of the elemental mercury oxidation on commercial catalysts was studied in simulated gas. Three species of SCR catalyst, $V_2O_5-TiO_2$ type, were selected. The elemental mercury reduced 30% without HCl gas in SCR operating condition. But the width of reduction increased 60% at 20 ppm HCl gas. According to the result of field measurement, reduction rate of elemental mercury at SCR outlet showed 60%. The total mercury concentration decreased about 20%. The results were similar to the lab test. The results of chemical analysis of test sample showed increase of mercury concentration but surface change was not observed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.5
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• pp.126-132
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• 2007

We propose a power factor correction scheme using a LC resonant circuit in commercial frequency without switching devices. In this method, It makes a sinusoidal wave by widening conduction period using the current resonance in commercial frequency, Hence, the harmonic characteristics can be significantly improved, where the lower order harmonics, such as the fifth and seventh orders are much reduced. The result are confirmed by the theoretical and experimental implementations

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.233-237
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• 2000

Propagation losses including bath transmission losses and bending losses of the flexible dielectric tube waveguide using commercial polymer substances for a short distance millimeter wave transmission are analytically predicted. The transmission loss and the bending loss are strongly dependent on the power flow distributions in each region. The obtained propagation tosses are compared with those of the commercial metal rigid and flexible waveguides.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.16-21
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• 2005

The performance of reciprocating internal combustion engine is a strong function of the air intake system configuration. In order to improve engine power, it is essential to optimize the air induction system. In this study, a numerical investigation has been carried out for the three-dimensional flow and pressure characteristics in air intake system of a large-sized commercial bus. CFD simulations using STAR-CD were also perform ed to evaluate effects of intake duct geometry and structure variation inside air cleaner on the negative pressure distribution of overall intake system. Studies for improving the back pressure distribution have been proposed and quantitatively examined based on intensive case studies.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1150-1152
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• 1998

Recently, our electric industry confronts a structural change and high competiveness environment in the course of deregulation. Rapid growth in electricity demand, financial need for new power plant construction, and envionmental problems have led to search for more efficient energy production and energy conservation techmologies. Especially, residential and commercial buildings consumes 40% of electricity demands and building energies are increasing more and more in Korea. The purpose of this paper is to analyze the electricity use of commercial buildings by end-use. Also, we will use it as a basic informations of DSM potential evaluation and evaluation process based on different approach by sector and type of potential.

• International Journal of Fluid Machinery and Systems
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• v.9 no.4
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• pp.332-337
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• 2016

Turbocompounding is a key technology to satisfy the future requirements of diesel engine's fuel economy and emission reduction. A turbocompound diesel engine was developed based on a conventional 11-Liter heavy-duty diesel engine. The turbocompound system includes a power turbine, which is installed downstream of a Variable Geometry Turbocharger (VGT) turbine. The impacts of the VGT rack position on the turbocompound engine performance were studied. An optimal VGT control strategy was determined. Experimental results show that the turbocompound engine using the optimal VGT control strategy achieves better performance than the original engine under all full load operation conditions. The averaged and maximum reductions of the brake specific fuel consumption (BSFC) are 3% and 8% respectively.