• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2020.11a
• /
• pp.41-42
• /
• 2020

본 논문에서는 JPEG Pleno에서 표준 데이터세트로 제공되고 있는 디지털 홀로그램의 압축 방법을 제시한다. 디지털 홀로그램의 재현에서 시각화를 위한 랜덤 위상의 추가는 간섭현상으로 인한 스페클노이즈와 더블어 홀로그램의 압축 효율을 떨어트린다. 먼저, 다양한 웨이블릿 필터를 이용하여 홀로그램 데이터에 대한 주파수 특성 분석을 진행한다. 다음으로, 홀로그램 압축에 용이한 필터를 제안한다. 마지막으로 JPEG2000의 웨이블릿 필터인 Bi-Orthogonal (4, 4)와 제안하는 웨이블릿 필터를 이용하여 SPIHT(Set partitioning in hierarchical trees)를 이용하여 압축하고 복원하고 압축률 대비 정량적 화질평가를 통해 그 효율을 분석한다.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.1
• /
• pp.48-55
• /
• 2018

The purpose of the present study is to compare the reduction rate of natural frequency and the increase rate of damping parameter with structural damage in system. For this purpose, experiment and numerical simulation analysis are performed for the 2-span H-Beam with lower natural frequency and higher damping parameter from free vibration in structure. The response signal by impact load before and after damage is analyzed at 14 locations. The response signals for all locations are performed fast fourier transform to estimate the natural frequency reduction rate and wavelet transform to estimate the damping parameter increase rate. The time domain function corresponding to each scale(frequency) is separated from the response signal by wavelet parameter. The estimation of damping parameter increase rate using wavelet transform is more sensitive than the estimation of natural frequency reduction rate in structure.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.11C
• /
• pp.905-916
• /
• 2008

In this paper, we propose a new method which estimates and encrypts significant component of digital hologram using discrete wavelet packet transform (DWPT). After analyzing the characteristics of digital hologram in spatial and frequency domain, the required information for ciphering digital hologram was extracted. Based on this information an ciphering method was proposed with wavelet transform and packetization of subbands. The proposed algorithm can encrypt digital hologram in various robust from selecting transform-level and energy threshold. From analyzing the encryption effect numerically and visually, the optimized parameter for encryption is presented. Without additional analyzing process, one can encrypt efficiently digital hologram using the proposed parameter. Although only 0.032% among total data is encrypted, the reconstructed object dose not identified. The paketization information of subbands and the cipher key can be used for the entire secret key.

• Journal of the Korea Society for Simulation
• /
• v.16 no.4
• /
• pp.13-22
• /
• 2007

Fault detection of cycle-based signals is typically performed using statistical approaches. Univariate SPC using few representative statistics and multivariate analysis methods such as PCA and PLS are the most popular methods for analyzing cycle-based signals. However, such approaches are limited when dealing with information-rich cycle-based signals. In this paper, process fault defection method based on wavelet analysis is proposed. Using Haar wavelet, coefficients that well reflect the process condition are selected. Next, Hotelling's $T^2$ chart using selected coefficients is constructed for assessment of process condition. To enhance the overall efficiency of fault detection, the following two steps are suggested, i.e. denoising method based on wavelet transform and coefficient selection methods using variance difference. For performance evaluation, various types of abnormal process conditions are simulated and the proposed algorithm is compared with other methodologies.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.26 no.5
• /
• pp.513-518
• /
• 2008

The research of global-scale mass redistribution and it changed by Earth gravity filed variation observations, including Earth's oblateness $J_2$(also called low degree spherical harmonic coefficient $C_{20}$), is in continuous progress. Recently, the comparative analysis of geodetic observation SLR can be made by the development of GRACE and other time-variable gravity measurements. In this study, $C_{20}$ time series changes in the value of comparative analysis was got by GRACE monthly Gravity filed model (CSR RL04) for the period April 2002 to May 2008. And comparative analysis the harmonic coefficients of $C_{20}$ was obtained from SLR observations. Signal analysis for two time-series data was made by wavelet transform, CWT(continuous wavelet transform), XWT(cross wavelet transform) and WTC(wavelet coherence) methods. The results indicate that GRACE and SLR values for $C_{20}$ had both decreasing trend, as well as SLR data represent the annual frequencies, and GRACE was semiannual variations. In addition, the results of GRACE and SLR had a strong correlation with the XWT and WTC in an annual cycle.

• Journal of the Korean earth science society
• /
• v.30 no.6
• /
• pp.692-698
• /
• 2009

Wavelet transform has been widely used in terms that it may overcome the shortcoming of conventional Fourier transform. Fourier transform has its difficulty to explain how the transformed domain, frequency, is related with time. Traditional semblance technique in Fourier transform was devised to compare two time series on the basis of their phase as a function of frequency. But this method is known not to work well for the non-stationary signal. In this study, we present two applications of the wavelet-based semblance method to geophysical data. Firstly, we show filtered geomagnetic signal remained with components of high correlation to each observatory. Secondly, highly correlated residual signal of gravity and magnetic survey data, which are also filtered by this semblance method, is present.

• Proceedings of the Korean Information Science Society Conference
• /
• 2001.04b
• /
• pp.577-579
• /
• 2001

본 논문에서는 웨이블릿 변환 기법으로 키프레임을 분석하여 객체 영역을 추출함과 동시에 가상의 객체 영상을 현실감있게 합성하는 기술에 대하여 연구하였다. 가상의 객체 영상이나 실물체 영상을 비디오 영상내에 삽입하여 좀 더 현실감있는 새로운 동영상 비디오 데이터를 제작하는 데 초점을 맞추어 연구를 진행하였다. 웨이블릿 변환이 새로운 영상을 재구성하는데 커다란 기여를 하였으며 본 논문에서 제시한 AR 영상 합성 기법은 동영상 데이터를 합성하는데 사용자가 원하는 지점에 정확하게 영상의 특성정보를 충분히 잘 살린 새로운 방법의 시도였다. 또한, 영상의 캘리브 레이션 방법을 거치지 않고 비디오 영상의 회전행렬과 위치성분을 계산하여 매핑된 가상의 객체 영상을 영상 보간법을 적용하여 직접 가사의 객체 영상을 비디오 객체 영상을 비디오 영상열에 삽입한다. 제시한 영상 합성 기법은 가상의 객체 영상이 디지털 동영상내에 삽입되었을 때 가장 큰 문제점인 떨림 현상과 부조화 현상이 제거되었다.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.10 no.4
• /
• pp.521-526
• /
• 2015

Research on how to use the biological characteristics of human to confirm the identity of the individual is being actively conducted. Electrocardiogram(: ECG) based biometric system is difficult to counterfeit and does not cause skin irritation on the subject. It can be easily combined with conventional biometrics such as fingerprint and face recognition to give multimodal biometric systems. In this thesis, biometric identification method analysing ECG waveform characteristics from Discrete Wavelet Transform(DWT) coefficients is suggested. Feature selection is performed on the 9 coefficients of DWT using the correlation analysis. The verification is achieved by using the error back propagation neural networks. Using the proposed approach on 24 subjects of MIT-BIH QT Database, 98.88% verification rate has been obtained.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.05a
• /
• pp.422-423
• /
• 2018

In this paper, we implement Frenelet transform for decomposition of the fringe pattern and analyze its characteristics. The implemented wavelet-like basis functions are well suited for reconstruction and processing of optically generated Fresnel holograms. After analyzing the characteristics of the B-spline function, we will discuss the wavelet-like multi-resolution analysis method. Through this process, we implemented a transform tool that can decompose fringe patterns effectively. We have implemented a B-spline function with various decomposition properties and showed the results of decomposing the fringe pattern.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.1
• /
• pp.489-492
• /
• 2005

In this paper, we present a system for robust face detection based on wavelet transform using the standard models of image distortion. In the previous works, it was known to be difficult to treat a distorting of image information such as noises and light of the images obtained by a still camera and a movie camera. we analyze the high frequence information by using wavelet transform. This information is used for testing the image distortion and constructing the standard models of image distortion. The experimental results show that our extracting method based on standard models of image distortion is very effective.