• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.490-491
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• 2006

Based on the real field test of 22.9kV HTS cable, which is installed in Gochang Power Testing Center located in Chonbuk Province, the standard for the performance test and the quality evaluation have been established. This work will be applied to the development of HTS cable and the purchase process as a practical material. In particular, new items for the cable evaluation such as the measurement of critical current and the heat loss, which was not dealt with in conventional cable, are specified in detail.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2362-2367
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• 2005

This paper reports a technique for discriminating double talk and echo path change using the stochastic characteristics of power change for an adaptive noise canceller. The causes of rapid error increasing are double talk and echo path change. When the echo path is changed, the system corrects the impulse response in order to reduce the error. However, in the case of double talk, the system has to suspend the updating impulse response in order to maintain the quality of the voice signal. In the conventional system, it was difficult to discriminate between the two situations. In this research, the stochastic characteristics of the voice power change in the double talk period were experimentally verified to be different from the power change during echo path changing. Based on the results, a new double talk detection method is proposed.

• Journal of Industrial Technology
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• v.31 no.B
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• pp.17-21
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• 2011

Since the railway passenger services have been recognized as important factor for success in railway, electrical energy consumption in railway station for high quality service has greatly increased. Furthermore, the number of the private railway station has gradually increased. Therefore, the operation conditions for railway power distribution system is dramatically changed in comparison with the past. So, this paper proposes the optimal construction method for railway power distribution system considering economical efficiency and the reliability of power supply to establish the railway power distribution system standard for the future railway industry.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.176-179
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• 2006

Large tubesheet forgings of the steam generator for the 1,400MW nuclear power plant has been developed. Steam Generator is one of the most important structural part for nuclear power plant. It is manufactured by various steel forgings such as shell, head, torus and tubesheet. These steel forgings have been made by open die forging process. After steel melting and ingot making, open die forging has been carried out to get a good quality which means high soundness and homogeniety of the steel forgings by using high capacity hydraulic press. This paper introduced the forging process development and manufacturing experience of large tubesheet forgings which will be used for the steam generator of 1,400MW nuclear power plant.

• Proceedings of the KIEE Conference
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• summer
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• pp.236-238
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• 2004

In recent years wind turbine technology has undergone the rapid development in response to the demands for increased use of renewable sources of energy. Using wind turbines for production of electrical energy requires reliable operation. The increased share of wind power in electrical system makes it necessary to have grid-friendly interfaces between the wind turbines and the grid in order to maintain power quality. Increasingly wind turbines are being connected into electricity distribution system. The grid-connected wind power stations have many impacts on power systems such as voltage variations, harmonics. The paper investigates the influences of grid-connected wind power generation system on substation bus voltage.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.259-261
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• 2002

Recently, according to the spread of semiconductor applied technology like motor speed control contrivance, power conversion installation and so on, harmonic ingredients occurred in switching operation flow into a distribution system and increase voltage distortion of distribution system and bring on obstacles like damage, lowering of capability, false operation and so on of various electrical installation. So, in order to consider a countermeasure to limit occurrence quantity of harmonic source, harmonic interception and others, precision measurement and analysis on voltage, current, power, power factor, the each ingredient of harmonic order, the percentage of total harmonic distortion and so forth are needed. In this paper monitoring system to measure and analyze power quality connected with power harmonics was developed and it's performance is verified by measuring and analyzing three-phase voltage and current of R, S, T in the three-phase and four-wire system using the developed measurement system.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1308-1311
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• 2002

We present a low-power MPEG-4 video codec chip capable of delivering high-quality video data in wireless multimedia applications. The discussion will focus on the architectural design techniques for implementing a high-performance video compression/decompression chip at low power architectures. The proposed MPEG-4 video codec can perform 30 frames/s of QCIF or 7.5 frame/s of CIF at 27MHz for 128k∼144kbps. By introducing the efficiently optimized Frame Memory Interface architecture, low power motion estimation and embedded ARM microprocessor and AMBA interface, the proposed MPEG-4 video codec has low power consumption for wireless multimedia applications such as IMT-2000.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.971-982
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• 2015

In order to improve the quality of the billet continuous casting, a two-phase orthogonal power supply (TPOPS) for electromagnetic stirrer is researched, which is composed of three-phase PWM rectifier and three-leg inverter. According to the power analysis of system, the ripple of dc-link voltage is analyzed and its analytical expression is derived. In order to improve the performance of electromagnetic stirring, an integrated control method with feedforward control is proposed for PWM rectifier to suppress the fluctuations of dc-link voltage and provide a stable dc source for inverter. According to the simplified equivalent model, a composite current control method is proposed for inverter. This proposed method can combine the merits of feedforward control with feedback control to effectively improve the dynamic output performance of TPOPS. Finally, a 300kVA prototype of TPOPS is developed, and the results have verified the analysis and control method.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.431-435
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• 1998

This paper deals with the output characteristics of resonant PWM inverter type X-ray generators connected to different DC power units i.e. a single phase full bridge rectifier, a three phase full bridge rectifier and a power storage unit(PSU). The quality of X-ray beam depend on the pulsation waveforms of DC voltage supplied to the X-ray tulbe. In a X-ray generator, the waveforme of DC output voltage can be affected from hramonic distortion of DC input power. When a tube voltage waveform is distorded, the property of X-ray beam such as reproducibility, direcibility and doesage can be reduced. Therefore, we compared DC output waveforms and doesages with three thpe of DC power units and show the experimental results in this paper

• Journal of Power Electronics
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• v.16 no.2
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• pp.532-541
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• 2016

A single-phase asymmetrical cascaded multilevel inverter is introduced with the goal of increasing power quality with the reduction of power in insulated-gate bipolar transistor (IGBT) switches. In the present work, the proposed inverter topology is analyzed and generalized with respect to different proposed algorithms for choosing different voltage source values. To prove the advantages of the proposed inverter, a case study involving a 17-level inverter is conducted. The simulation and experimental results with reduced THD are also presented and compared with the MATLAB/SIMULINK simulation results. Finally, the proposed topology is compared with different multilevel inverter topologies available in the literature in terms of the number of IGBT switches required with respect to the number of levels generated in the output of inverter topologies.