• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.150-151
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• 2017

This paper deals with the suppression of subharmonic current oscillation of V/F controlled high speed induction motor drive in turbo blower applications. High speed induction motor has a relatively low stator impedance for high speed operation and therefore the dc link voltage ripple may result in subharmonic current oscillation at the steady state in high speed operation. This paper shows that the subharmonic oscillation is caused by the dc link voltage ripple and also proposes the suppression method, which generates the compensation voltage through the proportional current controller to reduce the subharmonic current oscillation. The simulation and experimental results show that the proposed suppression method reduces the subharmonic current oscillation to the acceptable low level in turbo blower applications.

• Journal of Energy Engineering
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• v.22 no.2
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• pp.205-210
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• 2013

Cycle-to-cycle variation has long been recognized as limiting the range of operating conditions of spark ignition engines, in particular, under lean and highly diluted operation conditions. At a part load, some of the cycles tend to knock, while others may have incomplete combustion by the time the exhaust valve opens. An experimental study has been performed in order to evaluate the relative contribution of several relevant parameters on the cyclic variability in spark ignition engines. In general, the stability of engine operation is improved with fuel injector according to the optimal injection timing, but the stability of engine operation at idle is not improved compared with a practical gasoline engine. In this study, we investigated the relationship of the effect of operating conditions for the stability at low speed and load.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.370-376
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• 1993

In this paper, we present the voltage source algorithm for high speed and low torque ripple operation of a switched reluctance motor (SRM). The SRM has simpler structure than the traditional dc or ac motor. It has a high starting torque and can be operated in the wide range of speed. So it can be applied to various areas. But the SRM has some difficulties in driving circuit and controller due to the large inductance variations. In this study, in order to produce the low torque ripple and the high speed operation, a voltage source algorithm is proposed. We showed the good performance of the proposed controller through simulation and experiment.

• Journal of Navigation and Port Research
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• v.33 no.1
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• pp.1-7
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• 2009

Navigation speed control is an important factor to improve the traffic safety, it is only researched about maximum speed control until now. Recently, there are lots of the low speed vessels including towing boats, carry heavy shipbuilding blocks in the Korean waters, so the danger degree of navigating vessels was increasing more and more. This paper analysed the effectiveness of minimum speed control with the operation burden's decrease, and it proposed the proper the minimum navigation speed of each traffic volume. Main results of this research are as follows. (1) in the case of 5 ships/hour, minimum speed control is effective if the lowest speed is fixed more than 5kts. (2) in the case of more than 10 ships/hour, speed control is some effective if the lowest speed is established 7kts. (3) But, when there are many ships in the waters, minimum speed control is not effective because distances between ships become near and ships navigate for a long time by a lot of ship having a few difference of relative speed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.32-36
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• 2002

High-speed movement and high-precision machining are the two most important requirements of present machine tool structures to reduce machining time and to increase the precision of products in various industrial fields such as semiconductor, automobile, and mold fabrication. The high speed operation of machine tools tue usually restricted not only by the low stiffness but also by the low damping of machine tool structures, which induces vibration during high speed machining. If the damping of machine tool structures is low, self induced or regenerative vibrations are bound to occur at high speed operation because the natural frequencies of machine tool structures can not be increased indefinitely. Therefore, the high damping capacity of a machine tool structure is an important factor for high speed machine tool structures. Polymer concrete has high potential for machine tool bed due to its good damping characteristics. In this study, a polymer concrete bed combined with welded steel structure i.e., a hybrid structure was desisted and manufactured for a high-speed gantry-type milling machine through static and dynamic analyses using finite element method. Then the dynamic characteristics were tested experimentally.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1685-1690
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• 2010

This paper describes the calculation and application of the speed profile for the train speed control when the train is operated by ATO(Automatic Train Operation). We propose a speed profile calculation method considering the speed limitation and the jerk limitation, in order to maintain the quality of the train automatic operation. In previous works, ATO calculates a desired speed profile along the time, and controls the train to follow the profile. In this case, it may be hard to follow the restrictive speed along the location or to stop the train with a low location error, because of the difference between the desired location at each time and the real location of the train due to the control error. In the proposed method in this paper, we calculate a desired speed profile along the time considering the speed and jerk limitation first, and derive a speed profile along the location using it. If the restrictive speed profile is changed or the train speed strayed from the speed profile, ATO system calculates new speed profile and applies it immediately. Because ATO system controls the train speed based on the train location, the accuracy of the train location control can be improved. A simulation system for the test of the automatic train operation using this method is designed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.338-343
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• 2010

Low cost motor drives are being sought for high volume energy efficient home appliances. Key to the realization of such low cost motor drives is to reduce the power electronic converter in terms of its components, particularly the active devices, finding the motor with least complexity for manufacturing and a controller that could extract the desired performance from the machine and converter combination. These and other factors such as self-starting, speed control over a wide range and most of all the crowning aspect of a four quadrant operation with bare minimum number of controllable switch (or switches) remain as formidable challenges for low cost motor drive realization. In this paper, a four quadrant switched reluctance motor (SRM) drive with only one controllable switch is realized by using a two-phase machine. The theory and operation of the proposed four-quadrant SRM drive with the proposed control algorithm for its realization are described. The motor drive is modeled, simulated and analyzed to verify its feasibility for self-starting, speed control and for four quadrant operation and the simulation results are presented. Experimental results confirm the validity of the proposed control algorithm for four quadrant control of the SRM drive. The focus of the paper is mainly directed toward the control algorithm for realizing the four-quadrant operation of the two-phase SRM drive with a single controllable switch converter.

• International Journal of Precision Engineering and Manufacturing
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• v.2 no.1
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• pp.33-42
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• 2001

In switched reluctance motor(SRM) deives, the turn-on and turn-off angles of each phase switch should be accurately controlled for accuracy and efficiency. The accuracy of the switching angles is mainly dependent upon the resolution of the encoder and the sampling period of the microprocessor, that are used to provide the information of the rotor position and to implement a control algorithm of the SRM, respectively. Thus, the higher the speed of the SRM is increased, the larger the amount of the switching angle deviations are from preset turn-on and turn-off angles. Consequently, the motor can not be driven stably high speed region. There fore, a simples and low cost encoder suitable for the practical and stable SRM drive is proposed and the control algorithm to provide the switching signals using a simple digital logic circuit is also presented for a wide speed range operation.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.05b
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• pp.14-18
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• 2003

This paper presents the pipeline architecture for the low and column address generator of 2D DCT/IDCT(Discrete Cosine Transform/Inverse Discrete Cosine Transform). For the real time process of image data, it is required that high speed operation and small size hardware In the proposed architecture, the area of hardware is reduced by using the DA(distributed arithmetic) method and applying the concepts of pipeline on the parallel architecture. As a results, the designed pipeline of the low and column address generator for 2D DCT/IDCT architecture is implemented with an efficiency and high speed compared as the non-pipeline architecture. And the operation speed is improved about 50％ up. The design for the proposed pipeline architecture of DCT/IDCT is coded using VHDL.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.2
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• pp.159-165
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• 2016

Recently, active efforts are being made for future Si CMOS technology by various researches on emerging devices and materials. Capability of low power consumption becomes increasingly important criterion for advanced logic devices in extending the Si CMOS. In this work, a junctionless field-effect transistor (JLFET) with ultra-thin poly-Si (UTP) channel is designed aiming the sub-10-nm technology for low-power (LP) applications. A comparative study by device simulations has been performed for the devices with crystalline and polycrystalline Si channels, respectively, in order to demonstrate that the difference in their performances becomes smaller and eventually disappears as the 10-nm regime is reached. The UTP JLFET would be one of the strongest candidates for advanced logic technology, with various virtues of high-speed operation, low power consumption, and low-thermal-budget process integration.