• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.22 no.2
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• pp.117-128
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• 2024

The 300 concrete silo systems installed and operated at the site of Wolsong nuclear power plant (NPP) have been storing CANDU spent nuclear fuel (SNF) under dry conditions since 1992. The dry storage system must be operated safely until SNF is delivered to an interim storage facility or final repository located outside the NPP in accordance with the SNF management policy of the country. The silo dry storage system consists of a concrete structure, liner steel plate in the inner cavity, and fuel basket. Because the components of the silo system are exposed to high energy radiation owing to the high radioactivity of SNF inside, the effects of irradiation during long-term storage must be analyzed. To this end, material specimens of each component were manufactured and subjected to irradiation and strength tests, and mechanical characteristics before and after irradiation were examined. Notably, the mechanical characteristics of the main components of the silo system were affected by irradiation during the storage of spent fuel. The test results will be used to evaluate the long-term behavior of silo systems in the future.

• Journal of Power Electronics
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• v.5 no.2
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• pp.83-98
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• 2005

As wind turbine technology and control has advanced over the last decade, this has led to a high penetration of wind turbines into the power system. Whether it be for a large wind turbine or an offshore wind farm with hundreds of MW power capacity, the electrical system has become more and more important in controlling the interaction between the mechanical system of the wind turbine and the main power system. The presence of power electronics in wind turbines improves their controllability with respect not only to its mechanical loads but also to its power quality. This paper presents an overview of a developed simulation platform for the modeling, design and optimization of wind turbines. The ability to simulate the dynamic behavior of wind turbines and the wind turbine grid interaction using four simulation tools (Matlab, Saber, DIgSILENT and HAWC) is investigated, improved and extended.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3365-3370
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• 2007

We developed micro power generation system using piezoelectric materials. In our system, the ambient vibrating energy is converting to electric energy by deflection of piezoelectric beams. The system consists of energy generating parts, converting enhancement parts, electric regulation and charging parts, and interface with small-energy-consuming mobile devices. The geometry of piezoelectric beams, the source of vibrating energy, and the electric load of target application determine the characteristics of generating electric power, such as impedance, voltage, current and power density. Therefore, we made a model for analysis of generating power with given information such as piezoelectric materials, geometry, vibration type, and mass. With this model, we can calculate capacitance of piezoelectric beams, generating voltage, current, and power. To obtain maximum energy transfer efficiency, we approached this study in the view of material, electrical, and mechanical engineering

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.4
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• pp.278-287
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• 2009

Plug-in hybrid electric vehicle (PHEV) with capability of being recharged from the power-grid will reduce oil consumption. Also, the PHEV will affect the utility operations by adding additional electricity demand for charging. In this research, the power-grid impact by demand of PHEV charging is presented and the optimal charging control strategy for utility operators is proposed with simulated data. The penetration of PHEV is assumed to be 50% in the circumstances of Korean passenger car market and Korean power-grid market limitedly. To obtain smooth load shape and utilize the surplus electricity in power-grid at midnight and dawn, the peak of charging demand should be controlled to be located before 4:00 a.m., and the time slot which can supply the electricity power to PHEV should be allowed between 1:00 a.m.$\sim$7:00 a.m.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.2
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• pp.580-590
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• 1995

To design and develop a turbocharged engine, ti needs that many study must be preceded about the characteristics of engine performance. Especially, a basic data about deciding target power is urgently needed for which is practically useful for engine design. The power output of turbo-charged engine is dominated by engine speed, displacement, compression ratio, air fuel ratio and charge pressure ratio. Therefore, the independent effect of these factors on power output was clarified from experiment, and the experimental equation to predict the power was founded from there results. The predicted power output from the experimental equation was well coincided with power measured through experiment.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.5
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• pp.57-65
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• 2016

The power flow of an 8-speed automatic transmission was analyzed using a lever analogy for the manufacturing of planetary gears. From the analysis, we found that the engine power was split between the first and second double-pinion planetary gears (DPPG1 and DPPG2), and was then passed to the DPPG3 for the fourth speed. For the fifth speed, the engine power was split between the DPPG1 and DPPG3. For the speeds 6-8, the engine power was passed only to SPPG2, while the seventh speed contained the power circulation.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.1-11
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• 2003

The service reliability of power plants strongly depends on the excellent performance and integrity of hydrodynamic bearings. Consequently, the bearings must be properly designed so as to control vibration amplitudes of rotor due to mass unbalance in passing critical speeds and also suppress self-excited vibrations of rotor even over maximum rated speeds. Furthermore, the bearings must be designed so as to maintain required tribological performance even under severe operating conditions. However, various tribological troubles have been experienced in power plants in Japan. The actual troubles are analysed, focusing on not only direct mechanical causes but also specific bearing designs that surfaced the troubles. Furthermore human factors that decided such designs are also studied. The powerful database of troubles and analyses will contribute greatly to designing advanced power plants with enhanced service reliability in the future. To this end, trouble information should be disclosed, shared and transferred limitlessly. Cooperation of users of power plants is essential to making more advanced design specifications, because no one has easier access to operating and trouble information of power plants than users.

• Journal of Surface Science and Engineering
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• v.46 no.2
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• pp.55-60
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• 2013

Superhard TiN coatings were fabricated by DC and ICP (inductively coupled plasma) assisted magnetron sputtering techniques. The effect of ICP power, ranging from 0 to 300 W, on coating microstructure, preferred orientation mechanical properties were systematically investigated with HR-XRD, SEM, AFM and nanoindentation. The results show that ICP power has a significant influence on coating microstructure and mechanical properties of TiN coatings. With the increasing of ICP power, coating microstructure evolves from the columnar structure of DC process to a highly dense one. Grain sizes of TiN coatings were decreased from 12.6 nm to 8.7 nm with increase of ICP power. The maximum nanohardness of 67.6 GPa was obtained for the coatings deposited at ICP power of 300 W. Preferred orientation in TiN coatings also vary with ICP power, exerting an effective influence on film nanohardness.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.213-217
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• 2002

Power devices for high power drivers that need high switching speed (IGCT, HVIGBT) have been continuously developed. However, serial and parallel connections using several much cheaper, lower power capacity of devices than an expensive high power device are very useful methods in the aspect of cost down and high power application. Even the current and voltage unbalance problem is occurred at each devices. This unbalance characteristics are mainly caused by the differences of physical characteristics of each devices and the line inductance (stray inductance) of bus bars that consist of current path. This paper deals simulation analysis of serial connection of IGCTs and parallel connection of IGCTs using physical model of devices. And also, introduces the method to reduce the voltage and current unbalance problem.

• KEPCO Journal on Electric Power and Energy
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• v.8 no.1
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• pp.1-4
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• 2022

In this study, a tensile test, one of the mechanical tests, was performed with the collected natural aging ACSR. In order to be used as basic data for predicting the replacement cycle of ACSR, the tensile strength with the normal cables was compared for cables which was caused white rust due to exposure of the hard-drawn aluminum wire surface. Among the ACSR wires collected from various regions, white rust was found on the surface of the small wire, and by checking the tensile strength of them, we would like to suggest the criteria for the ACSR replacement cycle, focusing on changes in mechanical properties.