• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.4
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• pp.260-265
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• 2008

The arc-fault occurring in the customer system becomes the direct cause of electric fire. However, it is very difficult to identify the arc-fault using the existing fault detection mechanism because the magnitude of the fault current is very small. Accordingly, this paper analyzes the causes of arc fault and designs the basic detection mechanism of arc fault. And then, it proposes an signal processing-based arc-fault determination methodology which can enhance the of accuracy of the arc-fault determination by applying DFT/DWT to the voltage and current waveform. Finally, this paper showed the application methodology of the proposed signal processing based fault determination method by applying and analyzing DFT/DWT to an high voltage in-rush current waveform.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.187-188
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• 2015

본 논문은 시간영역에서 대칭좌표법을 사용한 전력품질 이벤트 검출에 관한 연구이다. sag, swell. interruption, harmonic, flicker, transients, notches, spike 등과 같은 전력품질 이벤트들이 이 방법으로 쉽게 검출된다. 본 방법은 웨이블릿, s-변환, 힐버트 변환 등의 방법이 가지고 있는 계산 부담이 없기 때문에 온라인 응용프로그램에 쉽게 사용될 수 있다. 단상 전력품질 이벤트 신호는 시간 영역에서 대칭요소를 계산하기 위하여 120도, 240도 위상차를 가지고 생성되는 다른 두 신호와 함께 이동되어 간다. 전력품질 이벤트 신호의 시작점(triggering point)은 역상분으로부터 쉽게 검출될 수 있고 이벤트는 정상분과 역상분의 합을 사용한 파형의 특징 분석으로 쉽게 분류될 수 있다. 시뮬레이션된 결과는 전력품질 이벤트의 검출과 분류를 위한 본 방법의 효과를 보여주기 위하여 다수의 전력품질 이벤트를 보여주고 있고 전력계통망 지락사고 시뮬레이션을 수행하여 유용성을 확인하였다.

• The Journal of the Korea Contents Association
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• v.11 no.4
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• pp.92-100
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• 2011

In this paper, we propose a novel blind digital watermarking method based on a cellular automata transform (CAT). CAT is based on dynamic systems known as cellular automata(CA) and uses transform bases which are differently defined by a rule number, the number of neighbors, the number of cells, and an initial state, etc. The proposed CAT based method is compared with a blind watermarking method based on DWT which is commonly used for a domain transform in signal processing. We analyse properties on changes of DWT coefficients and CAT coefficients under various attacks and determine optimal parameters for a watermarking method robust to attacks. The simulations show that the watermarked images with high PSNR and MSSIM look visually identical to originals and are robust against most of typical image processing attacks. Moreover, the proposed CAT based watermarking method is superior to the DWT based one in robustness to most of typical image processing attacks including JPEG compression, median and average filtering, scaling, cropping, and histogram equalization.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06c
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• pp.432-435
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• 2007

본 논문은 신원확인 수단으로 부각되어 관심이 높은 홍채인식에 대한 연구이다 홍채인식 시스템의 경우 홍채영역에 따라 각 영상들의 특징 값이 차지하는 비중이 서로 다르게 분포되어 있고 눈썹이나 조명에 의한 잡음으로 인하여 인식성능에 영향을 미친다. 이 경우 기존에 등록되어 인증된 사용자의 홍채영상일지라도 제대로 인식하지 못하거나 인증에 실패할 수 있으며, 실세계에서의 홍채영역 사용이 원활하지 못하게 된다. 그러므로 단일 생체인식 시스템에서 홍채인식을 할 경우, 중요한 특징을 그대로 유지하고 인식성능을 향상시키기 위해서 획득된 홍채 영상의 정규화와 전처리 과정을 거친 다음 홍채영역을 분할한 후 각 영역에서의 보정치 적용을 통한 특징추출 방법을 제안한다. 또한 웨이블릿 변환과 주성분 분석을 이용하여 인식 성능이 개선된 특징추출 방법임을 보인다.

• Science of Emotion and Sensibility
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• v.5 no.3
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• pp.53-59
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• 2002

The surface fibers on the fabric is one of decisive factors which affects human sensory evaluation as well as heat and moisture transfer characteristics. In this study the length and distribution of surface fibers that are extruded from the fabric surface of the wool/wool blend fabrics (14 wool fabrics and 10 wool blend fabrics) and its contribution to subjective sensory evaluation were investigated. In order to quantify the length and distribution of surface fibers, image analysis and wavelet transform technique were introduced. Instant warm-cool feeling of touch, Q$\_$max/, and contact area were also measured and related to the quantified surface fibers. To figure out the effect of surface characteristics on sensory evaluation, human sensory responses to three adjectives which represent surface characteristics and warm-cool feeling of touch were obtained and analyzed. The relationship between the quantified surface fibers assessed by wavelet energy and both warm-cool reeling of touch, Qmax, and human sensory response were discussed.

• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.5
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• pp.277-284
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• 2012

To meet the usage of discrete wavelet transform (DWT) on potable devices, this paper implements 2-level DWT using a reference many-core processor architecture and determine the optimal many-core processor. To explore the optimal many-core processor, we evaluate the impacts of a data-per-processing element ratio that is defined as the amount of data mapped directly to each processing element (PE) on system performance, energy efficiency, and area efficiency, respectively. This paper utilized five PE configurations (PEs=16, 64, 256, 1,024, and 4,096) that were implemented in 130nm CMOS technology with a 720MHz clock frequency. Experimental results indicated that maximum energy and area efficiencies were achieved at PEs=1,024. However, the system area must be limited 140mm2 and the power should not exceed 3 watts in order to implement 2-level DWT on portable devices. When we consider these restrictions, the most reasonable energy and area efficiencies were achieved at PEs=256.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.151-154
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• 2002

The objective of this study is to find the change of signal characteristics of matrix cracks due to the different specimen shapes. As the concept of the smart structure, monitoring of acoustic emission (AE) can be applied to inspect the fracture of the structures in operating condition using built-in sensors. To understand the characteristics of matrix crack signals, we performed tensile tests by changing the thickness and width of the specimens. This paper describes the implementation of time-frequency analysis such as wavelet transform (WT) fur the quantitative evaluation of fracture signals. The experimental result shows the distinctive signal features in frequency domain due to the different specimen shapes.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.391-398
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• 2001

This paper presents the application method of a wavelet theory for identification of the structural dynamic properties of a bridge, which is based on the ambient vibration signal caused by the traffic loadings. The method utilizes the time-scale decomposition of the ambient vibration signal , i . e. the continuous wavelet transform using the Morlet wavelet is used to decompose the ambient vibration signal into the time-scale domain. The applicability of the proposed approach is verified through the reduced scale bridge and automobile system in the laboratory. The results of verification shows that the use of the Morlet wavelet to identify the structural dynamic properties is reasonable and practicable.

• Journal of Broadcast Engineering
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• v.24 no.1
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• pp.164-181
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• 2019

This paper introduces the analysis and development of digital holographic data codec technology to effectively compress hologram data. First, the generation method and data characteristics of the hologram standard data set provided by JPEG Pleno are introduced. We analyze energy compaction according to hologram generation method using discrete wavelet transform and discrete cosine transform. The quantization efficiency according to the hologram generation method is analyzed by applying uniform quantization and non-uniform quantization. We propose a transformation method quantization method suitable for hologram generation method through transform and quantization experiments. Finally, holograms are compressed using standard compression codecs such as JPEG, JPEG2000, AVC/H.264 and HEVC/H.265 and the results are analyzed.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.8
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• pp.87-96
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• 2014

In this paper, we propose a directionally adaptive aliasing and noise removal using dictionary learning based on space-frequency analysis. The proposed aliasing and noise removal algorithm consists of two modules; i) aliasing and noise detection using dictionary learning and analysis of frequency characteristics from the combined wavelet-Fourier transform and ii) aliasing removal with suppressing noise based on the directional shrinkage in the detected regions. The proposed method can preserve the high-frequency details because aliasing and noise region is detected. Experimental results show that the proposed algorithm can efficiently reduce aliasing and noise while minimizing losses of high-frequency details and generation of artifacts comparing with the conventional methods. The proposed algorithm is suitable for various applications such as image resampling, super-resolution image, and robot vision.