• Journal of Power Electronics
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• v.16 no.4
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• pp.1375-1386
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• 2016

To decouple the secondary saliencies in sensorless permanent magnet synchronous machine (PMSM) drives, a repetitive control (RC) in the angle domain is proposed. In this paper, the inductance model of a concentrated windings surface-mounted PMSM (cwSPMSM) with strong secondary saliencies is developed. Due to the secondary saliencies, the estimated position contains harmonic disturbances that are periodic relative to the angular position. Through a transformation from the time domain to the angle domain, these varying frequency disturbances can be treated as constant periodic disturbances. The proposed angle-domain RC is plugged into an existing phase-locked loop (PLL) and utilizes the error of the PLL to generate signals to suppress these periodic disturbances. A stability analysis and parameter design guidelines of the RC are addressed in detail. Finally, the proposed method is carried out on a cwSPMSM drive test-bench. The effectiveness and accuracy are verified by experimental results.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.4
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• pp.380-388
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• 2006

A noisy behavior of the time domain passivity controller during the period of low velocity is analyzed. Main reasons of the noisy behavior are investigated through a simulation with a one-DOF (Degree of Freedom) haptic interface model. It is shown that the PO/PC is ineffective in dissipating the produced energy when the sign of the velocity, which is numerically calculated from the measured position, is suddenly changed, and when this velocity is zero. These cases happen during the period of low velocity due to the limited resolution of the position sensor. New methods, ignoring the produced energy from the velocity sign change, and holding the control force while the velocity is zero, are proposed for removing the noisy behavior. The feasibility of the developed methods is proved with both a simulation and a real experiment.

• Proceedings of the KSPS conference
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• 2002.11a
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• pp.64-69
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• 2002

This study concerns the constraints of English Poetic Meter. In English poems, the metrical pattern doesn't always match the linguistic stress on the lines. These mismatches are found differently among the poets. For the lexical stress mismatched with the weak metrical position, $*W{\Rightarrow}{\;}Strength$ is established by the concept of the strong syllable. The peaks of monosyllabic words mismatched with the weak metrical position are divided according to which side of the boundary of a phonological domain they are adjacent to. Adjacency Constraint I is suggested for the mismatched peak which is adjacent to the left boundary of a phonological domain; *Peak] and Adjacency ConstraintII for the mismatched peak which are adjacent to the right boundary of a phonological domain. These constraints are various according to the poets(Pope, Milton and Shakespeare) : *[Peak [-stress], $W{\Rightarrow}{\;}*Strength$ and *Peak] in Pope; *[+stress][Peak [-stress] and *Peak] in Milton ; *[+stress][Peak [-stress], $W{\;}{\Rightarrow}{\;}*Strength$ and ACII in Shakespeare.

• The Journal of the Acoustical Society of Korea
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• v.27 no.1E
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• pp.11-16
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• 2008

In this paper, a pitch cycle waveform (PCW) is extracted, quantized, and interpolated in a time domain to synthesize high-quality speech at low bit rates. The pre-alignment technique is proposed for the accurate and efficient PCW extraction, which predicts the current PCW position from the previous PCW position assuming that pitch periods evolve slowly. Since the pitch periods are different frame by frame, the original PCW is converted into the fixed-dimension PCW using the dimension-conversion method, and subsequently quantized by code-excited linear predictive (CELP) coding. The excitation signal for the linear predictive coding (LPC) synthesis filter is generated using the time-domain interpolation and interlink of the quantized PCW's. The coder operates at 4.2 kbit/s and 3.2 kbit/s depending on the pitch period. Informal listening test demonstrates the effectiveness of the proposed coding scheme.

• Korean Journal of English Language and Linguistics
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• v.2 no.4
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• pp.555-574
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• 2002

This study concerns the constraints of English Poetic Meter. In English poems, the metrical pattern doesn't always match the linguistic stress on the lines. These mismatches are found differently among the poets. For the lexical stress mismatched with the weak metrical position, W⇒ Strength is established by the concept of the strong syllable. The peaks of monosyllabic words mismatched with the weak metrical position are divided according to which side of the boundary of a phonological domain they are adjacent to. Adjacency Constraint I is suggested for the mismatched peak which is adjacent to the left boundary of a phonological domain; /sup */Peak] and Adjacency ConstraintⅡ for the mismatched peak which is adjacent to the right boundary of a phonological domain. These constraints are various according to the poets (Pope, Milton and Shakespeare) : /sup */[Peak [-stress], /sup */W⇒ Strength and /sup */Peak] in Pope; /sup */[+stress][Peak[-stress] and /sup */Peak] in Milton; /sup */[ +stress][Peak[-stress], /sup */W⇒Strength and Adjacency ConstraintⅡ in Shakespeare.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.597-599
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• 2019

When frequency domain high amplitude impulse is inserted before IFFT in OFDM transmitter, the PAPR of OFDM signal in tme domain can be effectively reduced. In this paper, the degree of PAPR improvement of OFDM communication system with CQAM subcarrier modulation is analysed by adopting impulse insertion technique before IFFT of transmitter. Furthermore, it is verified that additional PAPR performance improvement can be obtained by finding optimum position of impulse insertion for maximizing PAPR reduction.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.9
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• pp.1029-1039
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• 1992

This paper presents the filtering method which is processed on the frequency domain among Hangul character recognition methods. It is processed the Hangul character parrern with spatial positioning modulation and mapped the Hangul character element which have spatial position variant feature onto frequency domain, at this time, normalized spatial position and so normalized the character size in frequency domain. And it is grouped the Hangul character element according to the generating position and set the standard pattern, and used each standard character element pattern with character element filter and filtering the character pattern of Hangul character, it is derived the normalized cross correlation function and the coherence function led to the filtering results, and calculated classification threshold.

• Journal of Advanced Navigation Technology
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• v.28 no.1
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• pp.155-158
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• 2024

Multipath, a major error source in urban GNSS positioning (global navigation satellite system), pose a challenge due to its site-dependent nature, varying with the user's signal reception environment. In our previous study, we introduced a technique generating GNSS multipath map in urban canyon. However, due to uncertainty in initial GNSS positions, applying multipath maps required generating multiple candidate positions. In this study, we present an efficient method for applying multipath maps by projecting the multipath correction in position domain. This approach effectively applies multipath maps, addressing the challenges posed by urban user position uncertainties.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.620-628
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• 2005

Spatial control of sound is essential to deliver better sound to the listener's position in space. As it can be experienced in many listening environments, the quality of sound can not be manifested over every position in a hall. This motivates us to control sound in a region we select. The primary focus of the developed method has to do with the brightness and contrast of acoustic image in space. In particular, the acoustic brightness control seeks a way to increase loudness of sound over a chosen area, and the contrast control aims to enhance loudness difference between two neighboring regions. This enables us to make two different kinds of zone - the zone of quiet and the zone of loud sound - at the same time. The other perspective of this study is on the direction of sound. It is shown that we can control the direction of perceived sound source by focusing acoustic energy in wavenumber domain. To begin with, the proposed approaches are formulated for pure-tone case. Then the control methods are extended to a more general case, where the excitation signal has broadband spectrum. In order to control the broadband signal in time domain, an inverse filter design problem is defined and solved in frequency domain. Numerical and experimental results obtained in various conditions certainly validate that the acoustic brightness, acoustic contrast, direction of wave front can be manipulated for some finite region in space and time.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.85-88
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• 2002

In this paper, the proposed watermark algorithm is based on energy distribution of the subband coefficients in the frequency domain and edge of the original image in the spacial domain. Out of these information, the KeyMap which decides the embedded position of watermark is produced. And then the binary watermark is embedded into the wavelet coefficient of LL3 subband using KeyMap and LFSR(Linear Feedback Shift Register).