• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.690-692
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• 2003

The single phase switched reluctance motor has been studied and developed actively in the various applications with several kinds and forms because of the developments of the design technique by using the computer and of the driving technique power electronic technology, which has the merits of a simple and robust structure, and first of all reducing the number of the switching devices in comparison with poly phase switched reluctance motor. And also, the studies are making progess to substitute the switched reluctance motor for single phase induction motor. In the previous studies, the single phase switched reluctance motor for the drive of blower is designed with the design theory of the conventional rotating electric machine and poly phase switched reluctance motor. In this paper, we intend to select the optimal pole arc and pole pitch ratio by the FEM analysis, because the pole arc and pole pitch are very important factor to determine the characteristics of switched reluctance motor.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.5
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• pp.39-51
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• 2014

This paper deals with design of a direct-coupled, small-scaled permanent magnet generator (PMG) for wind power application. First, this paper determines rated power and speed of the PMG from measured characteristics of wind turbines. Second, we derive analytical solutions for the open-circuit field in order to determine optimum magnet thickness and pole pitch/arc ratio. Third, on the basis of open circuit field solutions, stator magnetic circuit including slot opening, teeth width and yoke thickness is designed. And then, a diameter of stator coil which agree with a required current density is calculated, and its turns are determined from the area of slot considering winding packing factor. Finally, finite element (FE) method is employed in analyzing the details of the designed PMG and, test results such as back-emf measurements are given to confirm the design.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1177-1179
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• 2005

This paper presents the characteristic analysis of slotless tubular type Linear DC Motor with Permanent Magnet excitation as variation of magnetic pole-pitch ratio. The stator armature winding of this motor is designed to wind at inner stator around the mover mounted with permanent magnet. First the practical model of this motor is made and its parameter is measured, after this simulation is carried out. Comparing the simulation results as variation of pole-pitch ratio, it can be seen that the reaching ability makes it useful in applications requiring a small, direct-drive actuator, which is required to extend into a specially constrained environment.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1358-1360
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• 2002

This paper presents a modeling and simulation of a utility-connected wind energy conversion system with a link of a rectifier and an inverter. It discusses the maximum power control algorithm for the wind turbine and presents the relationship of wind turbine output, rotor speed, power coefficient, tip-speed ratio and wind speed when the wind turbine is operated under the maximum power control algorithm. The control objective is to extract maximum power from wind and transfer the power to the utility. This is achieved by controlling the pitch angle of the wind turbine blades. Pitch control method is mechanically complicated, but the control performance is better than that of the stall regulation method. The simulation results performed on MATLAB will show the variation of generator's rotor speed, pitch angle, and generator output.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.1
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• pp.49-56
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• 2003

The hydrodynamic interference between two circular cylinders in tandem and side by side arrangements was investigated by measuring of lift and drag on each cylinder. The time variations of interference lift and drag coefficients in each arrangement were observed at center-to-center pitch ratios of P/D=1.25 and 2.5 and Reynolds number of $Re=1.5\times10^4$. Average interference lift and drag coefficients were also observed at pitch ratios from P/D=1.25 to 2.5 and Reynolds number from $Re=1.5\times10^4$ to $1.5\times10^4$. The hydrodynamic interference between two circular cylinders differed with the shape of the arrangement and the pitch ratio, but the characteristics were revealed by measuring of lift and drag on each cylinder.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.607-610
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• 1998

The major objectives of speech coding include high compression ratio for transmission in the band limited channel, high synthesized speech quality in terms of the intelligibility and the naturalness and fast processing speed. In general, speech coding methods are classified into the following three categories: the wavelform coding, the source coding and the hybird coding. In this paper, we proposed a new waveform coding method using PSOLA(pitch-synchronous overlap add) technique. First, we fixed one basic waveform per pitch and measured the formant similarity between basic and neighbor waveform. Second, if the similairy satisfied threshold values, we compress the neighbor waveform per pitch and then store or transmit. When the comparession is about 45%, we obtained about 4 in MOS.

• Speech Sciences
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• v.14 no.4
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• pp.115-128
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• 2007

The purposes of this paper were to develop an automatic script to collect such acoustic parameters as duration, intensity, pitch and the first two formant values of English words produced by two native Canadian speakers either alone or in a two-word phrase at a normal speed and to compare those values by the position in the phrases. A Praat script was proposed to obtain the comparable parameters at evenly divided time point of the target word. Results showed that the total duration of the word in the phrase was shorter than that of the word produced alone. That was attributed to the pronunciation style of the native speakers generally placing the primary word stress in the first word position. Also, the reduction ratio of the male speaker depended on the word position in the phrase while the female speaker didn't. Moreover, there were different contours of intensity and pitch by the position of the target word in the phrase while almost the same formant patterns were observed. Further studies would be desirable to examine those parameters of the words in the authentic speech materials.

• MALSORI
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• no.27_28
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• pp.89-109
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• 1994

This thesis compares the duration aspect of the Daegu tongue with that of standard Korean. In the former study on the rhythm of standard Korean, one of the purposes of the study was to compare it with dialects. This thesis is the first attempt to do that. For this purpose, this thesis proceeds as follows. After Introduction, Chapter 2 surveys the former study. Chapter 3 deals with the materials, method and results of the experiment. Chapter 4 analyzes and interprets the results of the experiment, In Conclusion, the most Prominent fact is that the results of the experiment fall short of Daegu tongue speakers' expectations. The Daegu tongue is generally considered as a 'tone language.' And as Daegu tongue speakers sensitively recognize pitch, they think that they quickly say the syllables between the Pitch stressed syllables, whereas standard Korean speakers say those syllables relatively slowly, But in this experiment, which deals with only duration ignoring Pitch, their assumption is proved to be false.

• Proceedings of the KSPS conference
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• 2007.05a
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• pp.281-284
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• 2007

This experimental study aims to find out the correlation between semantic predictability and pitch-accent realization. For the experiment, we classified the predictability into three degrees: unpredictable, implicitly predictable, and explicitly predictable. And then each degree divided into to two subcatergories: one is adverbs/adverbial phrases of time or place and the other one is not time or place adverbs/adverbial phrases. The materials used in the experiment were 9 sentences for the each subcategory. One male and one female English native speakers participated in this experiment. Their reading speeches were recorded on Digital Audio Tape. Their speech data were analyzed by using Pitchworks program. The results of this experiment show pitch accented ratio is somewhat in inverse proportion to the degree of predictability.

• Carbon letters
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• v.8 no.4
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• pp.335-339
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• 2007

Carbon/silicon composites were synthesized by mixing silicon powders with petroleum pitch and subsequent heat-treatment. The resultant composites were composed of carbon and nano-size crystalline silicon identified by XRD and EDX. FIB images and SEM images were taken respectively to detect the existence of silicon impregnated in carbon and the distribution of silicon on the carbon surface. The obtained carbon/silicon materials were assembled as half cell anodes for lithium ion secondary battery and their electrochemical properties were tested. The pitch/silicon composite (3 : 1 wt. ratio) heat treated at $1000^{\circ}C$ and mixed with 55.5 wt.% of graphite showed relatively good electrochemical properties such as the initial efficiency of 78%, the initial discharge capacity of 605 mAh/g, and the discharge capacity of 500 mAh/g after 20 cycles.