• Journal of Institute of Control, Robotics and Systems
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• v.13 no.11
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• pp.1040-1047
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• 2007

This paper presents ripple-free method that can occur in multirate controller design. The conventional multirate input controller has the problem that the ripple occurs in track-following because of chattering phenomenon in control input signal. In order to resolve the problem of rippling, it was proposed to eliminate the ripple phenomenon using feedforward compensator. This paper makes explains problems in conventional ripple-tree multirate controller and introduces a multirate controller design method applying lifting technique based on current estimators in condition space. Using the ripple-tree multirate controller, we show that chattering does not occur in the control input signal through applying the final value theorem from the viewpoint of discrete-time transformation. Also, this study proves that the ripple of the proposed controller decreases with the increase of this sampling frequency and, when sampling frequency is fixed, it decreases with the increase of the control input period.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.3
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• pp.199-206
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• 2016

This paper describes a simple routing control system. We propose achieving high-speed data transmission without modifying the data frame configuration. To add a routing control signal, called the "labeling signal" in this paper, to the data frame, we use a frequency modulation technique on the transmitted frame. This means you need not change the data frame when you transmit additional signals. Using a prototype system comprising a field-programmable gate array and discrete elements, we investigate the system performance and devise a method to achieve high resolution. A three-channel routing control for a 10 Gb/s data frame was achieved, which confirms the advantages of the proposed system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.2
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• pp.495-513
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• 2020

The correlation identification of the subsurface is a novel electrical prospecting method which could suppress stochastic noise. This method is increasingly being utilized by geophysicists. It achieves the frequency response of the underground media through division of the cross spectrum of the input & output signal and the auto spectrum of the input signal. This is subject to the spectral leakage when the cross spectrum and the auto spectrum are computed from cross correlation and autocorrelation function by Discrete Fourier Transformation (DFT, "To obtain an accurate frequency response of the earth system, we propose an improved correlation identification method which uses all phase Fast Fourier Transform (APFFT) to acquire the cross spectrum and the auto spectrum. Simulation and engineering application results show that compared to existing correlation identification algorithm the new approach demonstrates more precise frequency response, especially the phase response of the system under identification.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.265-267
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• 2004

A blind separation problem in a multiple-input-multiple-output (MIMO) linear time-invariant (LTI) system with finite-alphabet inputs is considered. A discrete-time matrix equation model is used to describe the input-output relation of the system in order to make full use of the advantages of modern digital signal processing techniques. At first, ambiguity problem is investigated. Then, based on the results of the investigation, a new identifiability condition is proposed for the case of an input-data set which is widely used in digital communication. A probability bound such that an arbitrary input matrix satisfies the identifiability condition is derived. Finally, Monte-Carlo simulation is performed to demonstrate the validity of our suggestions.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.105-106
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• 2011

전력계통에서 비선형부하와 시변부하 사용의 증가 및 분산전원의 보급 증가로 전력품질(power quality)에 대한 관심이 증대되고 있다. 전력계통에서 전력품질은 전력신호를 통해 모니터링이 가능하다. 하지만 전력신호 상시 관측을 통한 전력품 모니터링은 많은 신호 데이터양이 필요하여 전력 신호 압축이 요구된다. 이에 따라 본 연구에서는 신호 압축 성능이 우수한 DCT(discrete cosine transform)기법을 이용하여 전력신호를 압축, 복원하는 방법을 제안한다. 그리고 DSP (digital signal processor) 보드를 통해서 압축 저장 된 신호를 오차 범위 5% 이내로 복원한다. 따라서 정전과 같은 이벤트(event)가 발생하였을 때 특정시간, 장소에서의 전압과 전류 파형을 볼 수 있게 한다. IEC 61000-4-30, IEEE std 1159에 근거하여 Matlab 프로그램 상에서의 성능을 평가하고 DSP보드를 이용하여 DCT를 이용한 데이터압축 시스템을 구현하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.431-434
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• 2003

As a wavelet transform which is presented as a new technique of signal processing field has time and frequency localization capabilities, it's possible for multiresolution analysis as well as easy to analyze various signal. So it is being applied in many fields recently. And when two wavelet base were designed to form Hilbert transform pair, wavelet pair show superior performance than the existing DWT(discrete wavelet transform) in data detection of pulse type. Therefore in this paper, we detected position of impulse noise by using two dyadic wavelet base which is designed by truncated coefficient vector.

• Journal of Information Processing Systems
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• v.13 no.2
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• pp.340-347
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• 2017

A watermark is a signal added to the original signal in order to preserve the copyright of the owner of the digital content. The basic challenge for designing a watermarking system is a dilemma between transparency and robustness. If we want a higher rate of transparency, there has to be a compromise in terms of its robustness and vice versa. Also, until now, watermarking is generalized, resulting in the need for a specialized algorithm to work for a specialized image processing application domain. Our proposed technique takes into consideration the image characteristics for watermark insertion and it optimizes transparency and robustness. It achieved a 99.98% retrieval efficiency for an image blurring attack and counterfeits other attacks. Our proposed technique counterfeits almost all of the image processing attacks.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.3
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• pp.362-368
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• 2009

Electrical fires have been occurred continuously in spite of installing ELB. Therefore the concern with the electrical arc-fault that cause the fire has growing. This paper measured series arc fault currents by the method of arc generator test in UL standard 1699. The used analysis methods in this paper are three different ways using DWT(discrete wavelet transform) those are frequently used for the arc fault current signal analysis. The arc fault detection probability is 100 % by method using noise-energy/shoulder-duration ratio of approximation coefficient. As these results, the variation of noise-energy and shoulder-duration ratio of approximation coefficient are founded important factors for the analysis of arc fault.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.10
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• pp.3591-3606
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• 2014

In this paper, a robust watermarking scheme is proposed that uses the scale-invariant feature transform (SIFT) algorithm in the discrete wavelet transform (DWT) domain. First, the SIFT feature areas are extracted from the original image. Then, one level DWT is applied on the selected SIFT feature areas. The watermark is embedded by modifying the fractional portion of the horizontal or vertical, high-frequency DWT coefficients. In the watermark extracting phase, the embedded watermark can be directly extracted from the watermarked image without requiring the original cover image. The experimental results showed that the proposed scheme obtains the robustness to both signal processing and geometric attacks. Also, the proposed scheme is superior to some previous schemes in terms of watermark robustness and the visual quality of the watermarked image.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.7
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• pp.302-307
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• 2002

Digital watermarking is the technique, which embeds an invisible signal including signal including owner identification and copy control information into multimedia data such as audio, video, and images for copyright protection. A new MPEG watermark embedding algorithm using complex block effect based on the Human Visual System(HVS) is introduced in this paper. In this algorithm, $8{\times}8$ dark blocks are selected, and the watermark is embedded in the DC component of the discrete cosine transform(DCT) by using quantization and modulus calculation. This algorithm uses a blind watermark retrieval technique, which detects the embedded watermark without using the original image. The experimental results show that the proposed watermark technique is robust against MPEG coding, bitrate changes, and various GOP(Group of Picture) changes.