• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.52-58
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• 2005

The concept of the Micro-Grid comprising Micro-Sources supplying both heat and power ranging from several [KW] to 1[MW] to local customers is proposed by CERTS(Consortium for Electric Reliability Technology Solutions). Micro-Sources adopt environmentally friendly and reliable power sources such as Fuel-Cell and Micro-Turbines. Micro-Sources adopt voltage source inverter with AC grid system in order to provide independent real and reactive power control for premium power quality. Thus Micro-Source needs series inductance for interfacing with AC grid system. With this reason, we propose a technique that can decide the optimal size of the inductor for effective transfer of the power into the grid.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.35-41
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• 2009

This paper proposes a stand alone type single-phase fuel cells micro-source with a voltage sag compensator for compensating the ac output voltage variations (sag or swell) of micro-source. The proposed micro-source is consist of a PEM(polymer electrolyte membrane) fuel cells simulator, a full bridge de converter, a 60Hz PWM(pulse width modulation) VSI(voltage source inverter), and a voltage sag compensator. Voltage sag compensator is similar to the configuration of hybrid series active power filter, and it is directly connected to micro-source through the injection transformer. Compensation algorithm of a voltage sag compensator adopts a single phase p-q theory. Effectiveness of the proposed the system is verified by the PSIM(power electronics simulation tool) simulation in the steady state and transient state which the proposed system is able to simultaneously compensate the harmonic current and source voltage sag or swell.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.280-282
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• 2005

Micro-source units having power ratings in thousands of watts can provide even higher reliability and fuel efficiency than the conventional large scale units. These units are also clustered with loads creating micro-grid services to customer sites such as office buildings, industrial parks and homes. Micro-sources adopt voltage source inverter to ensure the power quality of sensitive loads. This paper deals with the connection of micro-sources into the system grid. Modeling and simulation of the grid connected micro-sources at the power frequency range are investigated. Simulation results show that the micro-grid system with two micro-sources has good dynamic characteristics.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.7
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• pp.46-53
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• 2007

Micro-grid consists of micro-sources which adopt environmentally friendly and reliable power sources such as Fuel-Cell and Micro-Turbines with independent real and reactive power control capability for providing premium power quality. This paper deals with the basic aspect of dynamic modeling and the stability analysis of the micro-grid system. The fundamental frequency model of the micro-source inverters are considered to form a dynamic model of the micro-grid system Stability analysis is performed based on the linearized dynamic model of the micro-grid system Case study results show the parameters affecting the stability of the micro-grid.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.5
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• pp.841-847
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• 2007

This paper deals with the micro-grid consisting of micro-sources which adopt voltage sourced inverters with independent real and reactive power control capability for providing premium power quality. This paper presents dynamic modeling and the stable operating range of the micro-grid system varying the parameters of the micro-sources. The fundamental frequency model of the micro-source inverters are considered to form a dynamic model of the micro-grid system. Stability analysis is performed based on the linearized dynamic model of the micro-grid system. Case study results show the parameters affecting the stability of the micro-grid and the stable operating range of the micro-sources.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.8
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• pp.419-422
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• 2001

This paper presents the principle and fabrication of a novel micro mass spectrometer and emission test of hot electron for ionization. A micro mass spectrometer consists of a micro ion source and a micro ion separator. The micro ion source consists of a hot filament and grid electrodes. Electrons emitted from a hot filament are to ionize some sample molecules. The ions are accelerated to an ion detector by an electric field. Mass can be analyzed by using the time of fight depending on the mass-to-charge ratio. The current of hot electron emission from the hot filament is measured for various input voltages.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.3
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• pp.12-19
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• 2006

Micro-source units having power ratings in thousands of watts can provide power quality with higher reliability and efficiency than the conventional large scale units. This paper develops switching level model of micro-source and studies the characteristics of the micro-grid consisting of multiple micro-sources and interfaced with electric power system. The developed model adopts the space vector PWM to fully utilize the capacity of inverter. The interaction of the grid connected micro-sources and the characteristics of the control system parameters are investigated. Micro-sources and micro-grid are implemented using PSCAD/EMTDC. Simulation results show that the proposed model is efficient for studying micro-grid system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.457-464
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• 2007

Micro-Grid comprising Micro-Sources supplying several $kW{\sim}MW$ power to local customers is environmentally friendly and reliable. This paper deals with the development of simulation models of Micro-Grid on the PSCAD/EMTDC platform for analyzing various aspects of the interaction of the Micro-Grid. The developed switching level model adopts the space vector PWM. Both switching level and power frequency Micro-Source models are developed, which shows that power frequency modeling is sufficient for analyzing the phenomena of interest. Control characteristics of the Micro-Sources with the parameter and load power variation are analyzed for power quality enhancement. The simulation results show that the developed models are effective for studying Micro-Grid.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.42-48
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• 2009

Microgrid supplies loads with power interconnected grid. And it is defined a independent power system compounded micro sources over two devices which have enough capacity to operate independently, storage devices and loads. The energy sources of micro source have different dynamic characteristics corresponding to classes and application skills. However their transient responses are various from a few seconds to minutes. Therefore it is limitation for understanding operation characteristics of microsource modeling constant voltage source or constant current source. This paper shows that we designed EMTP/RV model of micro source which is microturbine based energy source. And we performed dynamic analysis of micro source corresponding to operation mode of microgrid.

• Journal of the Semiconductor & Display Technology
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• v.9 no.1
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• pp.17-21
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• 2010

Currently miniaturized electron-optical columns find their way into electron beam lithography systems. For better lithography process, it is required to make smaller spot size and longer working distance. But, the micro-columns of the multi-beam lithography system suffer from chromatic and spherical aberration, even when the electron beam is exactly on the symmetric axis of the micro-column. The off-axis error of the electron emitting source is expected to become worse with increasing off-axis distance of the focusing spot. Especially the electron beams far from the system optical axis have a non-negligible asymmetric intensity distribution in the micro-column. In this paper, the effect of the off-axis e-beam source is analyzed. To analyze this effect is to introduce a micro-column model of which the e-beam emitting source is aligned with the center of the electron beam by shifting them perpendicular to the system optical axis. The presented solution can be used to analysis the performance of the multi-electron-beam system. The performance parameters, such as the working distances and the focusing position are obtained by the computational simulations as a function of the off-axis distance of the emitting source.