• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1144_1145
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• 2009

Tidal power station is using the difference of the ebb and flow and the single action tidal power is dependent on tide amplitude and basin volume. Therefore the inflow of basin in rainy season has also effect on the daily power. Also if operating units are changed then starting head too changed. Therefore the number of units are very important for the optimization model. According to our study the primary point when we make a determination of optimization is starting head and governorl control mode. On this study optimization model for tidal power station is considered all of this conditions.

• Journal of Electrical Engineering and Technology
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• v.6 no.3
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• pp.369-374
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• 2011

An induction motor operated with high voltage source generally generates high current in starting mode and has a long transient time after being started. This large and sustaining starting current causes the end windings of the stator to have excessive electromagnetic force. This force is the source of vibration and has a negative and serious influence on the insulation of end windings. Therefore, designing the end winding part with an appropriate support system is needed. To design the support ring enclosing the end windings, we analyze the distribution of electromagnetic force on the end windings by applying the Biot-Savart's law and the 3D finite element method (FEM), and comparing two simulation methods. Finally, we verify the safety of the support structure of the end winding part using stress analysis, which is analyzed with the electromagnetic forces from the 3D FEM simulation.

• International Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.62-66
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• 2015

The starting processes of the Ludwieg tube hypersonic quiet tunnel plays very important role in the achievement of the quiet flow in the test section, which could affect the confidence coefficient of the data in the hypersonic transition experimental investigations. Thus, numerical analysis on that processes could help to understanding the running mode of the Ludwieg tube quiet tunnel and the propagation principle of the expansion wave series. To verify our computational method, the same parameter of the BAM6QT (the Boeing/AFOSR Mach-6 quiet tunnel at Purdue University) is used to compute, and it is agrees with our computational results.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.6
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• pp.588-599
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• 1992

This paper describes the variable speed drive of an induction motor by the line commutated inverter, which is operated in the forced commutation mode from start-up to operating point of load commutation. A novel forced-commutation circuit is proposed in this paper. The selection range of leading condenser to decide load commutation starting point is simulated by the sampling data of a general purpose IM and a high speed IM. The experiment to drive IM by a line commutated inverter with the proposed forced commutated circuits is performed. There was no problem in driving IM from standstill to starting point of load commutation by a line commutated inverter with forced commutation.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.215-217
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• 2008

This paper suggests a overvoltage protection scheme for HID lamp. HID lamp has complex characteristics and long duration in process from starting to steady state condition. So it is necessary to protect both starting and normal lighting mode. The protection method is composed of two circuit: one is for ignition state and the other is for steady state.

• Journal of the Optical Society of Korea
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• v.17 no.2
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• pp.177-181
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• 2013

We present an all-fiberized power-scalable, sub-nanosecond mode-locked laser based on a frequency-shifted-feedback ring cavity comprised of an erbium-doped fiber, a downshifting acousto-optic modulator (AOM), and a bandpass filter (BPF). With the aid of the frequency-shifted feedback mechanism provided by the AOM and the narrow filter bandwidth of 0.45 nm, we generate self-starting, mode-locked optical pulses with a spectral bandwidth of ~0.098 nm and a pulsewidth of 432 to 536 ps. In particular, the output power is readily scalable with pump power while keeping the temporal shape and spectral bandwidth. This is obtained via the consolidation of bound pulse modes circulating at the fundamental repetition rate of the cavity. In fact, the consolidated pulses form a single-entity envelope of asymmetric Gaussian shape where no discrete internal pulses are perceived. This result highlights that the inclusion of the narrow BPF into the cavity is crucial to achieving the consolidated pulses.

• Land and Housing Review
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• v.3 no.2
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• pp.169-175
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• 2012

In recent, there are many studies associated with energy piles to save initial construction cost for ground source heat pump system. In this study, to evaluate geothermal exchange rates two types (a connection type and a slinky type) of cast-in-place energy piles (PRD, 4.5m in depth, 1,200 mm in diameter) were constructed for the tests and their efficiencies were compared with numerical analysis results. As a result, starting with operation, geothermal exchange rate gradually decreases due to exchange of lower ground temperature. In the case of connection type, temperature difference is $0.37^{\circ}C$ in heating mode and $0.34^{\circ}C$, in cooling mode, respectively. In addition, in case of a connection type, geothermal exchange rate in heating mode is 2,314W/m and in cooling mode, 252.2W/m whose value is 9% higher than in heating mode. In the case of slinky type, the average geothermal exchange rate in heating mode is 168.0W/m, which is about 27% lower than that of connection type.

• Journal of the Optical Society of Korea
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• v.1 no.1
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• pp.41-43
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• 1997

We report the operation of a self-adaptive vector phase conjugate laser (VPCL) oscillator which compensates intracavity polarization distortion and wavefront aberration simultaneously. The VPCL in Nd:YAG gain media produce an output with energy of 125mJ in a 20ns single-longitudinal-mode pulse at 10Hz, which is unaffected by intracavity polarization distortion.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.245-246
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• 2008

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.503-508
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• 2003

This paper proposes modified subspace iteration method for efficient frequency analysis of structures. Proposed method uses accelerated Lanczos vectors as starting vectors in order to reduce the number of iterations in the subspace iteration method. Proposed method has better computing efficiency than the conventional method when the number of desired frequencies is relatively small. The efficiency of proposed method is verified through numerical examples.