• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.145-146
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• 2011

A micro-grid (MG) is usually interconnected to the main grid through the dedicated line. Immediately after the removal of the grid supply, the MG should be disconnected and remain disconnected until the main grid is re-energized. It should detect islanding condition as soon as it happens to adjust the setting of the protection relays in the MG. This paper proposes an islanding detection algorithm for the MG based on the active and reactive power delivered to the dedicated line in the time domain. The performance of the proposed algorithm is verified under islanding conditions and fault conditions using the PSCAD/EMTDC simulator. The results indicate that the proposed algorithm can discriminate the islanding conditions from the various fault conditions.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.91-92
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• 2011

Beat is a phenomenon, where the magnitudes and frequencies of the voltage and the current fluctuate. This paper describes a quantitative analysis of the beat phenomenon of a wind farm using the envelope of a current during intertie/grid fault conditions. In this paper, the ratio of the crest to the trough of the envelope curve and the time interval between adjacent troughs are defined and used to evaluate the beat phenomenon quantitatively. Beat phenomena under various fault and wind conditions are analyzed. The proposed quantitative analysis seems simple but effective in the more understanding of beat phenomenon of a wind farm, and thus can be used as a basis for operation and/or protection of an intertie.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.93-94
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• 2011

This paper analyzes the shaft torsion of a doubly-fed induction generator (DFIG) for a wind farm collector system fault. When a fault occurs, the active power of the DFIG cannot be transmitted to the grid and thus accelerates the rotation of both the blade and the rotor. Due to the different inertia of these, the angle of deviation fluctuates and the shaft torsion is occurred. This becomes much severe when the rotational speed of the blade exceeds a threshold, which activating the pitch control to reduce the mechanical power. The torque, which can be sixty times larger than that in the steady state, may destroy the shaft. The shaft torsion phenomena are simulated using the EMTP-RV simulator. The results indicate that when a wind farm collector system fault occurs, a severe shaft torsion is occurred due to the activation of the pitch control.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1632-1635
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• 2007

We developed a novel growth method of CNTs on metal substrate for device applications, deposited by a triode direct current plasma enhanced chemical vapor deposition (dc-PECVD). With resist-assisted patterning (RAP) method, we had grown CNTs on metal substrate, which were strongly bonded with metal substrate.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.793-798
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• 2014

To generate finite-power Airy beams, a novel holographic method is proposed. We record the interference pattern between an Airy beam (signal beam) and plane wave (reference beam) on a photopolymer, then decode the hologram by illuminating with the reference beam. The reconstructed beams still present the non-diffraction, acceleration, and self-healing features of optical Airy beams. In addition, angular multiplexing of two Airy beams with opposite acceleration directions is presented.

• 대한생식의학회:학술대회논문집
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• 2004.11a
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• pp.71-71
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• 2004

• The Korea Genome Conference
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• 2002.08a
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• pp.38.2-38.2
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• 2002

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.150-155
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• 2006

Carbon nanotubes backlight unit (CNT-BLU) that lightened by field emission was developed into practicability. According to our novel structure, AC mode circuit design and simple printing process, CNT-BLU could achieve 85% of uniformity, 8000 nits of brightness and low material and fabrication cost. Based on these performances, this new planar backlight technology has chances to proceed to mass production and has the potential to replace traditional backlight technology because of its good properties, like the simple processes, easy to large scale, low surface temperature, low power consumption, optical film-free and Hg-free, etc.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.806-809
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• 2003

Ion-induced secondary electron emission coefficient $({\gamma})$. of the patterned MgO thin film with geometrical structures has been measured by ${\gamma}$ - FIB(focused ion beam) system. The patterned MgO thin film with geometrical structures has been formed by the mask (mesh of ${\sim}$ $10{\mu}m^{2})$ under electron beam evaporation method. It is found that the higher ${\gamma}$. has been achieved by the patterned MgO thin film than the normal ones without patterning.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2005.11a
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• pp.136-136
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• 2005