• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.3
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• pp.143-151
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• 2004

High-speed permanent magnet machines are likely to be a key technology for electric drives and motion control systems for many applications, since they are conductive to high efficiency, high power density, small size and low weight. In high-speed machines, the permanent magnets are often contained within a retaining sleeve. However, the sleeve and the magnets are exposed to high order flux harmonics, which cause parasitic eddy current losses. Rotor losses of high-speed machines are of great importance especially in high-speed applications, because losses heat the rotor, which is often very compact construction and thereby difficult to cool. This causes a danger of demagnetization of the NdFeB permanent magnets. Therefore, special attention should be paid to the prediction of the rotor losses. This paper is concerned with the rotor losses in permanent magnet high-speed machines that are caused by permeance variation due to stator slotting. First, the flux harmonics are determined by double Fourier analysis of the normal flux density data over the rotor surface. And then, the rectilinear model was used to calculate rotor losses in permanent magnet machines. Finally, Poynting vector have been used to investigate the rotor eddy current losses of high-speed Permanent magnet machine.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.820-826
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• 2014

It is well known that energy generated by a wind generator (WG) depends on the wind resources at the installation site. In other words, a WG installed in a high wind speed area can produce more energy than that in a low wind speed area. However, a WG installed at a low wind site can produce a similar amount of energy to that produced by a WG installed at a high wind site if the WG is designed with a rated wind speed corresponding to the mean wind speed of the site. In this paper, we investigated the power curve of a WG suitable for Korea's southwestern coast with a low mean wind speed to achieve a high capacity factor (CF). We collected the power curves of the 11 WGs of the 6 WG manufacturers. The probability density function of the wind speed on Korea's southwestern coast was modeled using the Weibull distribution. The annual energy production by the WG was calculated and then the CFs of all of the WGs were estimated and compared. The results indicated that the WG installed on the Korea's southwestern coast could obtain a CF higher than 40 % if it was designed with the lower rated speed corresponding to the mean wind speed at the installation site.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.83-85
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• 2003

This paper presents a speed control of permanent magnet synchronous motors (PMSM) using an adaptive integral binary observer without speed and position sensors. In view of composition with a main loop regulator and an auxiliary loop regulator, the binary observer has a property of the chattering alleviation in the constant boundary layer. In order to improve the steady state performance of the binary observer, the proposed adaptive integral binary observer is formed by adding extra integral dynamics to the switching hyperplane equation. The effectiveness of the proposed system is conformed by the experimental results.

• Journal of Welding and Joining
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• v.17 no.1
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• pp.71-76
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• 1999

The real-time holographic interferometer with digital high-speed camera is applied to the experimental study of laser induced plasma/plume in pulsed Nd:YAG laser welding. A pulsed Nd:YAG laser with 1.2 kW average power is applied to generate laser induced plume. The recording speed of the high-speed camera is 3,000 f/s. The high speed photographs of weld plume without another visualization method, are compared with the visualization photographs with holographic interferometer. The radiation intensity from the laser induced plume is recorded by the high speed photographs, which fluctuated during laser radiation and disappeared after laser end. The density distribution of the plume is recorded by the holographic visualization method. The experimental results show the process of generation of the laser induced plasma/plume, and give the feasibility of quantitative measurement of laser induced plume in laser welding.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.12
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• pp.2633-2640
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• 2009

We design a small-area, low-power, and high-speed EEPROM for touch screen controller IC. As a small-area EEPROM design, a SSTC (side-wall selective transistor) cell is proposed, and high-voltage switching circuits repeated in the EEPROM core circuit are optimized. A digital data-bus sensing amplifier circuit is proposed as a low-power technology. For high speed, the distributed data-bus scheme is applied, and the driving voltage for both the EEPROM cell and the high-voltage switching circuits uses VDDP (=3.3V) which is higher than the logic voltage, VDD (=1.8V), using a dual power supply. The layout size of the designed 128-KBit EEPROMIP is $662.31{\mu}m{\times}1314.89{\mu}m$.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.353-358
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• 2001

Turbo-charging or Super-charging has been used to boost engine power for Gasoline Engine and Diesel Engine came to the world at the beginning of $20^{th}$ century. So far Turbo-Charger has enjoyed a high reputation in the charging filed for its technical advantages such as no demand of operation power from engine and an excellent charging effect in the event of a static operation at mid- and high engine speed. A mechanically driven Super-Charger, however, is now emerging in order to meet demands of the age of speed such as high engine power for a quick change of the driving mode - high engine torque even at low engine speed. Since Super-Charger needs driving power from engine, it cannot improve its relatively higher fuel consumption against that of Turbo-Charger. This negative point is still an obstacle to the wide use of Super-Charger. Super-Charger using Screw-type compressor which has already had a considerable base in air compressor market will fulfill this purpose of improving fuel consumption by minimizing operation power owing to no charging at idling or partially loading driving. This study aims to develop power control concept to achieve this minimization of operation power.

• Proceedings of the KIEE Conference
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• summer
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• pp.1382-1384
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• 2004

It is essential to evaluate harmonic characteristics of high speed train using power electronics equipment such as converter-driven motor drives, battery chargers and auxiliary power supplies. The purpose of this study is to measure and analyze harmonics characteristics of korea high speed train prototype. This paper presents result of harmonics measurement and analysis of harmonics characteristics in terms of loading, speed and operation mode.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.4
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• pp.38-49
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• 1998

A fossil power plant can be modeled by a lot of algebraic equations and differential equations. When we simulate a large, complicated fossil power plant by a computer such as workstation or PC, it takes much time until overall equations are completely calculated. Therefore, new processing systems which have high computing speed is ultimately needed for real-time or high-speed(faster than real-time) simulators. This paper presents an enhanced strategy in which high computing power can be provided by parallel processing of DSP processors with communication links. DSP system is designed for general purpose. Parallel DSP system can be easily expanded by just connecting new DSP modules to the system. General urpose DSP modules and a VME interface module was developed. New model and techniques for the task allocation are also presented which take into account the special characteristics of parallel I/O and computation. As a realistic cost function of task allocation, we suggested 'simulation period' which represents the period of simulation output intervals. Based on the development of parallel DSP system and realistic task allocation techniques, we cound achieve good efficiency of parallel processing and faster simulation speed than real-time.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.737-741
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• 2003

The wind power system is spotlighted as one of the no-pollution power generation systems. The system uses winds as power source that are rotated the blade and the rotating power from blade generate the electricity power. Gearbox needs to transfer the wind powers that have the high-torque-low-speed characteristics to generator that have the low-torque-high-speed characteristics. Because the wind power system generally locates the remote place like seaside or mountainside and the gearbox installs on the limited and high placed space, the gearbox of the wind power system is required the optimal space design and high reliability. In this paper, the structure of the gearbox is proposed to achieve the optimal space and efficiency by compounding the planetary gear train that has the high power density and parallel type gear train that has the long service life. The design parameters that are affected the service life are studied. The gear ratio and face width are investigated as an affected parameter for design sensitivity of service life.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.227-230
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• 2009

In this paper, the results of field testing of high-speed power line in-home networking in Korea are reported. When multiple networks share a common channel, they can interfere destructively and reduce system capacity. This is major problem in-home power line communications, especially in MDU deployments. The effects of neighboring network interference in power line communications are reported.