• 한국지능시스템학회논문지
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• 제14권5호
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• pp.583-586
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• 2004

고밀도의 저장기록장치 채널의 주요 신호검출 오류의 원인은 천이 지터잡음이다. 이러한 채널환경에서 최적의 신호검출기 구현을 위해서는 고도의 복잡도가 요구되는데 이는 지터잡음이 신호와 상관관계가 있고 잡음간에도 상관관계가 존재하기 때문이다. 본 논문에서는 계산량과 하드웨어 복잡도 관점에서 효율적인 두 가지 종류의 신호검출기에 대해서 설명한다. 이는 전통적인 비터비 복호기의 가지값을 변화시킨 형태이며 같은 이진데이터 값의 반복을 제한하는 부호와 함께 결합하여 일반적인 PR 채널에 적용된다 기존의 비터비 알고리즘의 복잡도와 비교하면 비터비 트렐리스에서 각각의 가지값을 계산할 때 추가적으로 하나의 곱셈기 혹은 덧셈기의 증가가 요구된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.29-31
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• 2005

Detection methods for atrial tachycardia and fibrillation on the time axis have the advantages of light operational load and are easy to apply to various applications. Despite these advantages, arrhythmia detection algorithm on the time axis cannot stand much noise such as motion artifacts, moreover the peak detection algorithm has high complexity. In this paper, we use a spectrum analysis method for the detection of atrial tachycardia and fibrillation. By applying spectrum analysis and digital filtering on obtained electrogram signals, we can diagnose heart arrhythmia without using peak detection algorithm.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권3호
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• pp.142-145
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• 2006

Detection methods for atrial tachycardia and atrial fibrillation on the time axis have the advantages of light operational load and are easy to apply to various applications. Despite these advantages, arrhythmia detection algorithm on the time axis cannot stand much noise such as motion artifacts, moreover the peak detection algorithm has high complexity. In this paper, we use a spectrum analysis method for the detection of atrial tachycardia and atrial fibrillation. By applying spectrum analysis and digital filtering on obtained electrogram signals, we can diagnose heart arrhythmia without using peak detection algorithm.

• Smart Structures and Systems
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• 제28권6호
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• pp.779-789
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• 2021

Cracks in railway sleeper are an inevitable condition and has a significant influence on the safety of railway system. Although the technology of railway sleeper condition monitoring using machine learning (ML) models has been widely applied, the crack recognition accuracy is still in need of improvement. In this paper, a two-stage method using edge detection and convolutional neural network (CNN) is proposed to reduce the burden of computing for detecting cracks in railway sleepers with high accuracy. In the first stage, the edge detection is carried out by using the 3×3 neighborhood range algorithm to find out the possible crack areas, and a series of mathematical morphology operations are further used to eliminate the influence of noise targets to the edge detection results. In the second stage, a CNN model is employed to classify the results of edge detection. Through the analysis of abundant images of sleepers with cracks, it is proved that the cracks detected by the neighborhood range algorithm are superior to those detected by Sobel and Canny algorithms, which can be classified by proposed CNN model with high accuracy.

• 한국음향학회지
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• 제26권6호
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• pp.301-305
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• 2007

본 연구에서 관심을 갖는 수중환경에서의 천이소음도 가청주파수 대역임에 착안하여 이동통신 시스템의 표준 음성부호화기인 EVRC의 전처리단을 이용하여 배경잡음 구간을 판별하고 이를 바탕으로 수중 천이신호를 탐지하는 알고리즘을 제안하였다. EVRC 전처리 모듈에 프레임 단위의 입력신호가 들어가면 모듈로부터 잡음 구간을 결정하는 플래그, 각 채널의 에너지, 잡음이 제거된 신호, 입력신호의 에너지, 배경잡음의 에너지, 잡음이 제거된 신호의 에너지에 해당하는 파라미터 값을 얻게 된다. 잡음이 제거된 신호의 에너지를 배경잡음의 에너지로 정규화하고 이를 문턱값과 비교함으로써 천이신호를 검출할 수 있다. 또한 문턱 값은 잡음 구간에서 구한 이전 값을 이용해서 갱신된다. 실험결과를 통해 제안한 알고리즘이 백색 또는 유색잡음 하에서도 4% 미만의 오차를 보여주는 것을 검증한다.

• 한국해양공학회지
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• 제22권1호
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• pp.30-36
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• 2008

Underwater ambient noise originating from geophysical, biological, and man-made acoustic sources contains information on the source and the ocean environment. Such noise affectsthe performance of sonar equipment. In this paper, three steps are used to identify the ambient noise source, detection, feature extraction, and similarity measurement. First, we use the zero-crossing rate to detect the ambient noisesource from background noise. Then, a set of feature vectors is proposed forthe ambient noise source using the Hilbert-Huang transform and the Karhunen-Loeve transform. Finally, the Euclidean distance is used to measure the similarity between the standard feature vector and the feature vector of the unknown ambient noise source. The developed algorithm is applied to the observed ocean data, and the results are presented and discussed.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1627-1633
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• 2017

This paper proposes a voice enhancing ear-protection system which is based on feedback active noise control(FBANC). The proposed system selectively suppresses the background noise and preserves the talking voice by controlling the adaptive algorithm with the voice activity period detection module. The noise reduction performance of the proposed noise canceling algorithm is analytically derived for the two key performance affecting parameters, i.e., electro-acoustic coupling distance and noise bandwidth. The proposed system is also implemented with a floating-point DSP system and its performance is experimentally tested to compare with the analytically derived results. The achieved levels of noise reduction for the three different noise bandwidths cases, i.e., 10Hz, 50Hz, and 90Hz, are high to show 17.05dB, 10.54dB and 8.99dB, respectively. The feasibility of the proposed system is also shown by the peak noise reduction achieved more than 25dB while preserving the voice component in the frequency range between 200-800Hz.

• 한국정보통신학회논문지
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• 제21권7호
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• pp.1429-1434
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• 2017

기존의 안경 렌즈 흠집 검출 방법은 영상내의 미세 잡음이 제거되지 않아 렌즈 영역이 정확히 추출되지 않는 경우가 발생하여 흠집 영역을 검출할 수 없다는 문제점이 발생한다. 따라서 본 논문에서는 이러한 문제점을 개선하기 위해 적응적 이진화 기법과 Bresenham algorithm을 적용하여 흠집 영역을 검출한다. 제안된 방법은 안경 렌즈 영상에서 명암 대비를 적용하여 렌즈의 명암을 강조한다. 명암이 강조된 영상에서 렌즈 밖의 배경 영역은 흠집 검출에 불필요하므로 이진화 기법을 적용한 후에 Bresenham algorithm을 적용하여 렌즈의 윤곽선을 검출하고 렌즈 이외의 배경을 제거한다. 렌즈 이외의 배경이 제거된 렌즈 영상에서 렌즈 내부의 배경과 흠집의 명암 대비를 높인다. 명암이 강조된 렌즈 내부 영역에서 적응적 이진화 기법을 적용하여 흠집과 잡음을 검출한다. 잡음은 중간값 필터를 적용하여 제거한 후에 흠집 영역을 추출한다. 추출된 흠집 영역에서 렌즈의 중심으로부터의 거리와 흠집의 크기를 퍼지 추론 규칙에 적용하여 눈에 미치는 영향 정도를 분석한다. 제안된 방법의 성능을 분석하기 위해 CHEMI, MID, HL, HM과 같은 시력 보정용 렌즈 영상을 대상으로 실험한 결과, 12개의 시력 보정용 렌즈 영상 중에서 10개에서 결함을 성공적으로 추출하였다.

• KIEE International Transactions on Power Engineering
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• 제3A권4호
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• pp.214-221
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• 2003

In view of the fact that gas insulated switchgear (GIS) is an important piece of equipment in a substation, it is highly desirable to continuously monitor the state of equipment by measuring the partial discharge (PD) activity in a GIS, as PD is a symptom of an insulation weakness/breakdown. However, since the PD signal is relatively weak and the external noise makes detection of the PD signal difficult, it therefore requires careful attention in its detection. In this paper, the algorithm for detection of PD in the GIS using the wavelet transform (WT) is proposed. The WT provides a direct quantitative measure of the spectral content and dynamic spectrum in the time-frequency domain. The most appropriate mother wavelet for this application is the Daubechies 4 (db4) wavelet. 'db4', the most commonly applied mother wavelet in the power quality analysis, is very well suited to detecting high frequency signals of very short duration, such as those associated with the PD phenomenon. The proposed algorithm is based on utilizing the absolute sum value of coefficients, which are a combination of D1 (Detail 1) and D2 (Detail 2) in multiresolution signal decomposition (MSD) based on WT after noise elimination and normalization.

• 한국통신학회논문지
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• 제23권9A호
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• pp.2197-2210
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• 1998

In the grand alliance (GA) HDTV receiver, a coherent detection is empolyed for coherent demodulation of vestigial side-band (VSB) signal by using frequency and phaselocked loop(FPLL) operating on the pilot carrier. Additional phase tracking loop (PTL) employed to track out phase noise that has not been removed by the FPLL in theGA system. In this paper, we propose an algorithm for phase detection which utilizes a weighting function. The simplest implementation of the proposed algorithm using te sign of the Q channel component can be tractable by imposing a phase detection gain to the loop gain. It is obserbed that the propsoed algorithm has a robust characteristic against the performance of the digital filters used for Q channel estimation. A second goal of this paper is to introduce a gain control algorithm for the PTL in order to provide an effective implementation of the proposed phase detection algorithm. And we design the PTL through the realization of the simplified digital filter for H/W reduction. The proposed algorithms and the designed PTL are evaluated by computer simulation. In spite of using the simplified H/W structure, simulation results show that the proposed algorithms outperform the coventional PTL algorithms in the phase detection and tracking performance.