• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.8
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• pp.1-6
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• 1999

The only transmission characteristics in frequency domain is considered when using the tapered transmission line for wide-band impedance matching in MCM and MIC designs. In this paper, the distortion of an electrical pulse with rise/fall time resulting from dispersion and reflection as it propagates along a tapered microstrip line is investigated, and the delay time and distortion rate with respect to input and load impedances are analyzed on triangular and exponential tapered lines. A dispersion model of the phase constant proposed by Kirschning-Jansen is used to meet the frequency, accuracy and microstrip parametric requirements. The triangular tapered line shows both shorter delay time and higher distortion rate than those of the exponential tapered line. Furthermore, the amplitude of signal reflected from load point is calculated in time domain.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.11
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• pp.1645-1650
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• 2015

This paper presents the 3-dimensional electromagnetic field analysis method and correction of sensor distortion that is used by a motor speed sensor. The magnetic sensors are being expanded due to lower price than the other speed sensors such as resolver and encoder. Magnetic sensor generates sine and cosine waves when the motor rotates. However, the sine and cosine signals are distorted due to magnetic noise, which makes the angle error of the sensor, generated near by the Hall element. This paper defines an optimal design variables by using the Taguchi method to minimize output distortion of the magnetic sensor and permanent magnet. To enhance reliability of the magnetic position sensor from sensitivity error, assembly amplitude mismatch and the electrical angle, 3-Dimensional electromagnetic finite element method and correction algorithm errors were performed in due of the magnetic sensor in order to improve the quality of the initial production model.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.245-248
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• 2000

In this paper, we present the performance of a multi-code parallel combinatory CDMA system using bi-orthogonal modulation under multipath fading channel. In general, the dynamic range of the amplitude of the transmit signal is very large in conventional multi-code CDMA systems, resulting in severe nonlinear distortion due to high power amplifier and thus significant BER performance degradation. Since the number of simultaneously multiplexed code channels in the proposed system is reduced, the proposed system exhibits reduction of peak-to-average power ratio (PAPR) of the transmit signal amplitude with significant BER improvement. We verify the performance of the proposed system by computer simulations under the Vehicular B multipath fading channel model by ARIB.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.1
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• pp.28-34
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• 2003

In this paper, a predistortion linearizer using series diode is proposed for linearizing the power amplifier in microwave radio systems. The power amplifier should be operated near saturation region to achieve high efficiency. But at this region, amplitude and phase distortions of the amplifier remarkably increase with the increase of input power and cause a significant adjacent channel interference. The linearizer is composed of a series diode with a parallel capacitor, which provides positive amplitude and negative phase deviations with the increasing input power. This type of linearizer using the nonlinearity of diode has improved the C/I(Carrier to Intermodulation Distortion) ratio well. By applying this linearizer to two-tone 880MHz power amplifier, adjacent channel leakage power is improved up to 5dBm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.11
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• pp.1677-1688
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• 1993

Two dimensional amplitude scrambling algorithm using the hopping filter, which improve the drawback of conventional speech encryption scheme, is powerful encryption scheme in analog sppech signal. In this paper, we proposed the variable delay weight algorithm using hopping filter in order to solve the synchronization problem of two dimensional amplitude scrambling. Futhermore, analyzing the distortion of received signal which is transmitted in the gaussian noise channel, we determined the optimal encryption algorithm and optimal SNR using the simulation.

• Speech Sciences
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• v.11 no.4
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• pp.163-171
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• 2004

The primary goal of the present study was to explore more detailed evidence for the influence of aging and gender effects on the capability of Korean healthy, ears to generate DPOAEs. DPOAEs were examined in series of human subjects, with clinically nonnal hearing, ranging in age from 10 to 65 years. All 60 Koreans were divided into 6 age groups. Each age group included 10 participants, 5 females and 5 males. The gender effects on the difference between the absolute amplitude and noise floor value in DPOAEs did not exist. The difference increased as the frequency increased. The aging effects on the difference between the absolute amplitude and noise floor value in DPOAEs did exist. The difference increased as the frequency increased but orderly age effects could not be found. The principle finding was that, when compared between emissions in young and old ears, DPOAEs accurately tracked the systematic deterioration of high-frequency hearing in aging individuals. Such results support the need to reestablish the criterion for interpretation of DPOAEs in the elderly.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1210-1216
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• 2014

This paper deals with an application of Teager Energy Operator (TEO) and Energy Separation Algorithm(ESA) to detect and determine various voltage waveform distortions like harmonics, inter-harmonics and frequency variation. Because the TEO and DESA algorithm was initially proposed for speech or communication analysis, its applications are limited to some types of waveform in the power quality analysis area. For example, an undistorted voltage signal is similar with a pure sinusoid. A voltage fluctuation is very similar with an amplitude-modulated signal, from the viewpoint of signal theory. And a continuous frequency variation is similar with a frequency-modulated signal, which is also known as a chirp signal. This paper is written to show that the TEO and DESA algorithm can be used for detecting occurrences of the representative waveform distortions and determining their instantaneous information of amplitude and frequency.

• KIPS Transactions on Software and Data Engineering
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• v.4 no.9
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• pp.377-384
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• 2015

In this paper we propose a visualization tool for distortion-free time-series matching. Supporting distortion-free is a very important factor in time-series matching to get more accurate matching results. In this paper, we visualize the result of time-series matching, which removes various time-series distortions such as noise, offset translation, amplitude scaling, and linear trend by using moving average, normalization, linear detrending transformations, respectively. The proposed visualization tool works as a client-server model. The client sends a user-selected time-series, of which distortions are removed, to the server and visualizes the matching results. The server efficiently performs the distortion-free time-series matching on the multi-dimensional R*-tree index. By visualizing the matching result as five different charts, we can more easily and more intuitively understand the matching result.

• The Journal of the Acoustical Society of Korea
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• v.9 no.4
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• pp.66-76
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• 1990

In this work, the effect of noise and distortion of a telephone channel on the speech recognition is studied, and methods to improve the recognition rate are proposed. Computer simulation is done using the 100-word test data whichwere made by pronouncing ten times 100-phonetically balanced Korean isolated words in a speaker dependent mode. First, a spectral subtraction method is suggested to improve the noisy speech recognition. Then, the effect of bandwidth limiting and channel distortion is studied. It has been found that bandwidth limiting and amplitude distortion lower the recognition rate significantly, but phase distortion affects little. To reduce the channel effect, we modify the reference pattern according to some training data. When both channel noise and distortion exist, the recognition rate without the proposed method is merely 7.7~26.4%, but the recognition rate with the proposed method is drastically increased to 76.2~92.3%.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.4189-4202
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• 2014

In this paper, we propose a priority-based unequal error protection scheme of data partitioned H.264/AVC video with hierarchical quadrature amplitude modulation. In order to map data with higher priority onto the most significant bits of QAM constellation points, a priority sorting method categorizes different data partitions according to the unequal importance factor of encoded video data in one group of pictures by evaluated the average distortion. Then we propose a hierarchical quadrature amplitude modulation arrangement with adaptive constellation distances, which takes into account the unequal importance of encoded video data and the channel status. Simulation results show that the proposed scheme improves the received video quality by about 2 dB in PSNR comparing with the state-of-the-art unequal error protection scheme, and outperforms EEP scheme by up to 5 dB when the average channel SNR is low.