• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.207-214
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• 2000

In this paper, a study of the effenctiveness and convergency of five damage measures for structural damage detection of 2-dimensional truss structure using the extended Kalman filtering algorithm is presented. These damage measures are associated with the change in mode shape and displacement due to structural damage. Damage measures contain the change in natural frequency, mode shape, curvature of mode shape, displacement of static force and curvature of displacement of static force. The effectiveness and convergency of these damage measures by using extended Kalman filtering algorithm are demonstrated with the numerical examples.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.2
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• pp.344-354
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• 2009

Side scan sonar using acoustic wave plays a very important role in the underwater, sea floor, and shallow marine geologic survey. In this study, we have acquired side scan sonar data for the underwater man-made structures, artificial reefs and fishing grounds, installed and distributed in the survey area. We applied digital image processing techniques to side scan sonar data in order to improve and enhance an image quality. We carried out digital image processing with various kinds of filtering in spatial domain and frequency domain. We tested filtering parameters such as kernel size, differential operator, and statistical value. We could easily estimate the conditions, distribution and environment of artificial structures through the interpretation of side scan sonar.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.2
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• pp.89-96
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• 1998

Conventional block-based video coders induce annoying blocking artifacts in very low bitarte coding. We propose a delocking filter which is appropriate for real time operation in a conventional video decoder. The proposed algorithm uses on dimensional filtering across block boundaries horizontally and vertiaclly with two separate filtering modes. The mode decision is quite simple but is fully based on the characteristics of human visual system and video sequences. In flat regions, a strong smoothing filter is appliced; and in the other regions, a moew sophisticated smoothing filter, which is based on the frequency information around block boundaries, is used to reduce blocking artifacts without introuducing undesired blur. Eeven though the proposed deblocking filter is quite simple, simulation results show that it improves both subjective and objective image quality for various image features.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.4
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• pp.499-506
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• 2012

In this paper, a dynamic modeling for the velocity and position information of a single frequency stand-alone GPS(Global Positioning System) receiver is described. In static condition, the position error dynamic model is identified as a first/second order transfer function, and the velocity error model is identified as a band-limited Gaussian white noise via non-parametric method of a PSD(Power Spectrum Density) estimation in continuous time domain. A Kalman filter is proposed considering both correlated/white measurements noise based on identified GPS error model. The performance of the proposed Kalman filtering method is verified via numerical simulation.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.04a
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• pp.449-452
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• 2000

This paper proposes a new, adaptive Dead Reckoning model, called Dynamic Dead Reckoning , for Distributed Interactive Simulation and humanoid avatar systems. The proposed model can overcome the weak points of traditional Dead Reckoning caused by a fixed threshold and strong dependency on rotation event. This paper introduces new criteria for update message filtering , named as Update lifetime. The Dynamic Dead Reckoning keeps the balance between extrapolation fidelity and filtering performance by two component models, Variable Threshold Mechanism and Rotation Event model. The experimental results show that the proposed model can lower the increment rate of update traffic to the increase of rotation frequency without any significant loss of accuracy.

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.79-85
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• 1997

Fast spin echo imaging utilizes multiple spin echoes to encode multiple k-space lines instead of multiple $T_2-weighted$ images. As results, intensities in k-space data are varying according to T2 decay, which generates Gibb's artifact in the reconstructed image. The echo time for e encoding dc block determines contrast, as is specified by the effective echo time, however, all location of other echoes to different k-space frequency blocks in fast spin echo imaging is not f fully investigated. In this study, symmetric arrangement of multiple echoes in k-space is investigated to reduce Gibb's artifact. Design of filters based on the measurement of multiple e echo intensities is also proposed in two stage manner, i.e., equalization and filtering. From s simulation and experiment, it was observed that Gibb's phenomena were substantially reduced b by the proposed methods.

• International Journal of Ocean System Engineering
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• v.1 no.2
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• pp.89-94
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• 2011

Underwater localization is a crucial capability for reliable operation of various types of underwater vehicles including submarines and underwater robots. However, sea water is almost impermeable to high-frequency electromagnetic waves, and thus absolute position fixes from Global Positioning System (GPS) are not available in the water. The use of acoustic telemetry systems such as Long Baseline (LBL) is a practical option for underwater localization. However, this telemetry network system needs to be pre-deployed and its availability cannot always be assumed. This study focuses on demonstrating the validity of terrain-based localization techniques in a GPS-denied underwater environment. Since terrain-based localization leads to a nonlinear estimation problem, nonlinear filtering methods are required to be employed. The extended Kalman filter (EKF) which is a widely used nonlinear filtering algorithm often shows limited performance under large initial uncertainty. The feasibility of using a particle filter is investigated, which can improve the performance and reliability of the terrain-based localization.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.1
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• pp.72-80
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• 1988

In this paper, new adaptive interframe filtering methods have been proposed to separate the luminance and chrominance components in NTSC composite signals. In thess methods, the composite signals are adaptivelty processed in three dimensions according to the local change or movement of the picture. For interframe processing, two algorithms have been proposed which adapt three filters in the horizontal, vertical and temporal directions to the magnitude f detection signal dependent upon both the movement and local change of the picture. The three kind of filters have been used at the sampling rate of four times the subcarrier frequency. The various quantitative measures have been introduced to compare the objective performance of the conventional methods and that of proposed ones by computer simulation.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.487-490
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• 1999

In this paper we propose an efficient content-based image retrieval method using the color and wavelet based features. The color features are extracted from color histograms of the global image and the wavelet based features are extracted from the invariant moments of the high-pass band image through the spatial-frequency analysis of the wavelet transform. The proposed algorithm, called color and wavelet features based query(CWBQ), is composed of two-step query operations for efficient image retrieval: the coarse level filtering operation and the fine level matching operation. In the first filtering operation, the color histogram feature is used to filter out the dissimilar images quickly from a large image database. The second matching operation applies the wavelet based feature to the retained set of images to retrieve all relevant images successfully. The experimental results show that the proposed algorithm yields more improved retrieval accuracy with computationally efficiency than the previous methods.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.733-739
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• 2000

This paper is described the development of on-line partial discharge detector for high voltage apparatus. This detector consists of acoustic and high frequency current sensors, amplifier part, A/D converter part, data communication part and computer. The contents of paper are characteristics of units and digital signal processing for reducing noise in partial discharge detection. We seek methods to do good digital signal processing for detection of partial discharge. We apply digital filtering methods to the elect Tic signal and a cross con-elation to the acoustic signal. This paper shows the characteristics of these filtering method and cross con-elation in partial discharge detection.