• Journal of Power Electronics
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• v.17 no.2
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• pp.346-357
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• 2017

The Modular Multilevel Converter (MMC) is particularly attractive for medium and high power applications such as High-Voltage Direct Current (HVDC) systems. In order to reach a high voltage, the number of cascaded submodules (SMs) is generally very large. Thus, in the applications with hundreds or even thousands of SMs such as MMC-HVDCs, the sorting algorithm of the conventional voltage balancing strategy is extremely slow. This complicates the controller design and increases the hardware cost tremendously. This paper presents a Two-Way Merge Sort (TWMS) strategy based on the prediction of the capacitor voltages under ideal conditions. It also proposes an innovative Insertion Sort Correction for the TWMS (ISC-TWMS) to solve issues in practical engineering under non-ideal conditions. The proposed sorting methods are combined with the features of the MMC-HVDC control strategy, which significantly accelerates the sorting process and reduces the implementation efforts. In comparison with the commonly used quicksort algorithm, it saves at least two-thirds of the sorting execution time in one arm with 100 SMs, and saves more with a higher number of SMs. A 501-level MMC-HVDC simulation model in PSCAD/EMTDC has been built to verify the validity of the proposed strategies. The fast speed and high efficiency of the algorithms are demonstrated by experiments with a DSP controller (TMS320F28335).

• Transactions on Electrical and Electronic Materials
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• v.7 no.5
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• pp.240-246
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• 2006

The mathematical model of the power substation is proposed. The substation esteems as a set of the equipment elements which integrated common connections and electromagnetic field. Some capabilities of model represented by both electric networks and a discrete logical model demonstrated by non-directional graph. The model can be useful for solution of the problem of diagnostic of the high-voltage equipment.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.266-269
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• 2003

A sterilizer equipment by using electrical energy has merits that no process of chemical and no second environmental pollution. Also, the power conversion circuit for sterilizer equipment has merits that are reducing switching loss for soft switching topology by using zero current and zero voltage switching, and miniaturizing size of equipment. Thus, it is expected that the cost of sterilization process, when quality of the device is measured by power consumption, will be reduced. Therefore, the purpose of this research is to solve the sterilization problems of existing powder with plasma sterilization device, to find more economical and effective way, and to suggest more improved sterilizer.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.396-398
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• 2006

Predictive maintenance is not an unfamiliar concept because it has been used to predict the failures of electrical equipment such as transformers, motors and so on. By thoroughly monitoring the status of individual equipment and tracing how the various characteristics change over time, we can be aware of its exact condition and prevent the impending failure by taking appropriate actions. In this paper, I will extend the concept of predictive maintenance for individual electrical equipment to the power distribution system and show how to use the data obtained from power quality monitors to improve the power system.

• Carbon letters
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• v.25
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• pp.55-59
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• 2018

Carbon chain inserted carbon nanotubes (CNTs) have been experimentally proven having undergone pronounced property change in terms of electrical conductivity compared with pure CNTs. This paper simulates the geometry of carbon chain inserted CNTs and analyzes the mechanism for conductivity change after insertion of carbon chain. The geometric simulation of Pt doped CNT was also implemented for comparison with the inserted one. The results indicate that both modification by Pt atom on the surface of CNT and addition of carbon chain in the channel of the tube are effective methods for transforming the electrical properties of the CNT, leading to the redistribution of electron and thereby causing the conductivity change in obtained configurations. All the calculations were obtained based on density functional theory method.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.737-739
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• 1999

All equipment generally has a specified design service life. As an equipment nears the end of its design service life, replacement must be considered. In some cases, it is possible and more economical to continue the usage of the existing equipment for a longer period. So, replacement should be carefully decided considering the feasibility and economic benefits of the existing equipments' life extension. In this paper, assessment procedure for deciding between life extension and replacement of the electronic control system is presented with an application example. In particular estimation of the electronic control system's remaining life is focused on.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.213-215
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• 2006

A static frequency converter(SFC) in a pumped storage power plant is important equipment for converting electric motor kinetic energy into electric Bower. A SFC monitoring system consists of high voltage thyristor firing equipment, fault detection module, data gathering module, real time data processing equipment and man machine Interface system. This paper describes SFC system overview, developed SFC monitoring system configuration including system characteristics. and successful application result to San-Cheong pumped storage power plant.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.544-549
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• 1997

Injector of high voltage or linear ion accelerator is intended to generate, extract and form beam of certain species with required parameters at the entrance of accelerating structure or, for low energy case, directly in the processing chamber (end station). Injector is the main part defining the ion accelerator performance and reliability. Its power supply and control system (PSCS) features are conditioned by placing the injector equipment at high voltage potential and by complexity of the plasma-beam load. The injector's PSCS should provide: - Transmission of electric power onto high voltage (h/v) terminal; - Obtaining of required output characteristics for injector equipment operation; - Transmission of the operational data and start/stop signals from h/v terminal to control cabinet; - Rremote control of injector; - Withstanding the high voltage breakdowns and X-ray radiation; - Compatibility with other equipment. The paper is concerned with analysis of injectors' PSCS structure and description of the system developed for 50 keV, 20 mA heavy ion injector.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.270-273
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• 2004

The initial thermal analysis needs to be fast and efficient to reduce the feedback time for the optimal electronic equipment designing. In this study, a thermal model is developed by using power consumption measurement values of each functional breadboard, that is, semi-empirical power dissipation method. In modeling heat dissipated EEE parts, power dissipation is imposed evenly on the EEE part footprint area which is projected to the printed circuit board, and is called surface heat model. The application of these methods is performed in the development of a command and telemetry unit (CTU) for a geostationary satellite. Finally, the thermal cycling test is performed to verify the applied thermal analysis methods.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.357-359
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• 2003

This paper is for the transient analysis of instant short-circuit test equipment according to the test of tripping limits and characteristics under IEC 60947-2. The in-rush current is harmful to almost equipments and the exact testing is not made because of it. LGIS has a instant short-circuit test equipment, but it is not suitable for carrying out instant short-circuit test on ELB(Earth Leakage Circuit breaker) by reason of that. Now, I am going to show a solution for that problem. After applying this method, manufacturer is going to acquire the exact testing result according to the IEC standard. Moreover, Testing laboratory will be trusted by clients.