• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.543-550
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• 2016

The Active Superconducting Current Controller (ASCC) is a new type of Superconducting Fault Current Limiters (SFCL) which can limit the fault current in different modes. It also has the particular abilities of compensating active and reactive powers for electrical networks. In this paper, it is confirmed that the performance of ASCC in different operating modes introduces a limiting impedance in series with the network which can even degrade the transient stability and the operation of the Over-Current Relays (OCR) employed in a power system. In addition, the model of a three-phase ASCC is simulated, and the effect of descriptive modes on the current limiting level is investigated. For the transient stability analysis, a single machine-infinite bus system is tested, and the effect of operation modes is studied based on an equal area criterion obtaining the critical time and the critical angle. Modifying the setting parameters of OCR such as time dial and pick-up current, the protective coordination is also studied in different operating modes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.5
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• pp.317-322
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• 2014

Data security and integrity is a critical issue in data transmission over wired/wireless links. A large amount of data is encrypted before transmission, by block cipher using mode of operation. RBF mode is a block cipher mode of operation which uses random characteristics. In this paper, we analyze the safety against known plaintext attack and chosen plaintext attack of RBF mode compared to the traditional modes. According to the analysis, RBF mode is known to be secure while the traditional modes are not secure against them.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.1
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• pp.40-48
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• 2019

Hybrid electric propulsion systems (H-EPSs) are an intermediate step for integrated full electric propulsion warships. H-EPSs are a dynamic combination of mechanical and electrical propulsion systems to achieve the required mission performances. The system modes could adapt to meet the requirement of the various operation conditions of a warship. This paper presents a configuration and operating modes of H-EPSs considering the operation conditions of a destroyer class warship. The system has three propulsion modes, namely, motoring mode, generating mode [power take off (PTO) mode], and mechanical mode. The PTO mode requires a careful fuel efficiency analysis because the fuel consumption rate of propulsion engines may be low compared with the generator's engines depending on the loading power. Therefore, the calculation of fuel consumption according to the operating modes is performed in this study. Although the economics of the PTO mode depends on system cases, it has an advantage in that it ensures the reliability of electric power in case of blackout or minimum generator operation.

• Korean Chemical Engineering Research
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• v.46 no.2
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• pp.383-388
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• 2008

The safe and efficient operation of the chemical processes has become one of the primary concerns of chemical companies, and a variety of fault diagnosis methods have been developed to diagnose faults when abnormal situations arise. Recently, many research efforts have focused on fault diagnosis methods based on quantitative history data-based methods such as statistical models. However, when the history data-based models trained with the data obtained on an operation mode are applied to another operating condition, the models can make continuous wrong diagnosis, and have limits to be applied to real chemical processes with various operation modes. In order to classify operation modes of chemical processes, this study considers three multivariate models of Euclidean distance, FDA (Fisher's Discriminant Analysis), and PCA (principal component analysis), and integrates them with process dynamics to lead dynamic Euclidean distance, dynamic FDA, and dynamic PCA. A case study of the TE (Tennessee Eastman) process having six operation modes illustrates the conclusion that dynamic PCA model shows the best classification performance.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.2297-2302
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• 2010

The status and effectiveness of Bi-modal Tram is analyzed through the comparison of the transport effectiveness and operation cost between the public transportation systems (bus, light rail transit) considering the vehicle and operation characteristic of new transit system Bi-modal Tram. The standard operation schedule is established in consideration of the vehicle specification and operation characteristic of main public transportation modes, and then the annual average operation cost is estimated depending on the volume, speed, analysis length for respective public transportation mode. Through analyzing the operation cost and distribution characteristic of public transportation modes depending on the transport volume and travel speed, the operational efficiency suitable for the city is derived. It is concluded that the operational efficiency of Bi-modal Tram is superior to that of the bus and light rail transit on the aspect of travel volume and operation speed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.199-202
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• 2009

Scan design is currently the most widely used structured Design For Testability approach. In scan design, all storage elements are replaced with scan cells, which are then configured as one or more shift registers(also called scan chains) during the shift operation. As a result, all inputs to the combinational logic, including those driven by scan cells, can be controlled and all outputs from the combinational logic, including those driving scan cells, can be observed. The scan inserted design, called scan design, is operated in three modes: normal mode, shift mode, and capture mode. Circuit operations with associated clock cycles conducted in these three modes are referred to as normal operation, shift operation, and capture operation, respectively. In spite of these, scan design methodology has defects. They are power dissipation problem and test time during test application. We propose a new methodology about scan shift clock operation and present low power scan design and short test time.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.6
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• pp.864-871
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• 2015

Recently, one of the main research on the power distribution system is the microgrid. The microgrid is a combination of power sources and loads, which is controllable and has separable connection. The main objective of microgrid is the deployment of the renewable clean energy and the enhancement of load-side reliability. The modern power sources and loads have DC I/O interfaces, which is the major advantage of DC microgrid compared to the conventional AC grid. The components in the microgrid have diverse features, so there is need of proper coordination control. For achieving economic feature, the active power of renewable energy resources is regarded as major control parameter and the whole operation modes of DC microgrid are defined, and the proper operations of each component are described. From the inherent characteristics of DC, there are two control variables: voltage and active power. Through analysis of operation modes, it is possible to determine exact control objectives and optimized voltage & power control strategy in each mode. Because of consideration of whole operation modes, regardless of the number and capacity of components, this coordination control method can be used without modification. This paper defines operation mode of DC microgrid with several DC sources and suggests economic and efficient coordinated control methods. Simulation with PSCAD proves effectiveness.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1692-1699
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• 2015

This paper presents an analysis of the mechanism of failure modes in bi-directional phase-shift full-bridge converters, composed of MOSFET, based on the circuit operation and parasitic parameters of MOSFET. In addition, the relation between circuit operation and parameters is suggested through an experimental comparison. From this relation, the suitable ranges of parameters for stable performance are analyzed. The design criteria of the bi-directional phase-shift full-bridge converter are presented and evaluated from the experimental verification.

• Journal of Power Electronics
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• v.15 no.3
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• pp.849-859
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• 2015

This paper proposes a novel compound-type hybrid energy storage system (HESS) that inherits the unique advantages of both battery/supercapacitor (SC) and the SC/battery HESSs for electric vehicles (EVs). Eight operation modes are designed to match this system. A mode control strategy is developed for this HESS on the basis of these modes, and five classes of operation modes are established to simplify this strategy. The mode control strategy focuses on high operating efficiency and high power output. Furthermore, the compound-type HESS is designed such that the SC is the main priority in braking energy absorption. Thus, this HESS can operate efficiently and extend battery life. Simulation results also show that the compound-type HESS can not only supply adequate power to the motor inverter but can also determine suitable operation modes in corresponding conditions. Experimental results demonstrate that this HESS can extend battery life as well. The overall efficiency of the compound-type HESS is higher than those of the battery/SC and the SC/battery HESSs.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.746-755
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• 2009

This study will analyze the data of Kyongbu & Honam Line whether how much the weather change has an effect on the change of transportation modes and check the pattern of customer's behavior and investigate the influence on the changing transportation modes. Especially, this study will confine to the rainfall and snowfall out of various weather causes, and the questionnaire investigation is used to know the sensitivity of customer's patterns selecting transportation modes in accordance with weather change, and the research result will be used to make a marketing strategy & efficient train operation.