• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1155-1166
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• 2016

In this paper, we propose a new embedded video compression scheme which uses three-dimensional rate-distortion optimization based block coder. After the proposed scheme removes temporal redundancy by applying the motion compensated temporal filtering(MCTF) on input video frames, two dimensional discrete wavelet transform is applied on video frames to remove spatial redundancy. The three-dimensional wavelet coefficients generated in this way are sorted according to their expected rate-distortion slope and encoded by using the three-dimensional block partition coding method. The proposed scheme also uses both the effective color video coding method which maintains embedded features, and the efficient bit-rate control method. Experimental results demonstrate that the proposed scheme not only produces embedded bit-streams, but also outperforms existing video compression schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.8
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• pp.1774-1781
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• 1997

In this paper, we propose a full digital frequency and phase locked loop for CATV and HDTV receivers adopting VSB modulation. The CATV and HDTV receivers proposed by the Grand-Alliance in USA are ultilizing analog signal processing technology for carrier recovery. By the way, it is not a good architecture for the development of single chip ASIC operating in digital domain. To solve this problem while improving the performance, we first down convert the received r.f. signal to a near baseband signal for a low-rate AD converter and then we use digital signal processing techniques. The proposed system has the frequency pull-in range of -200 KHz +2.50 KHz. Moreover, it has the ability of adaptive loop bandwidth control according to the amount of frequency offset to improve the acquisition time while reducing the phase noise.

• Archives of design research
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• v.19 no.2 s.64
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• pp.313-322
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• 2006

In this paper, we introduce 'Contents Based Image Retrieval' which helps a user find the images he or she needs more easily and reconfigures the images automatically. With this system, we try to realize the language of (motion) picture, that is, the Montage from the viewpoint of the user. The Real-time Montage System introduced in this paper uses 'Discrete Fourier Transform'. Through this, the user can find the feature of the image selected and compare the analogousness with the image in the database. This kind of system leads to the user's speedy and effective retrieving, Also, we can acquire the movement image of the user by Camera Tracking in Real-time. The movement image acquired is to be reconfigured automatically with the image of the user. In this way, we can get an easy and speedy image reconfiguration which sets to the user's intention. This system is a New Media Design tool(entertainment) which induces a user enjoy participating in it. In this system, Thus, the user is not just a passive consumer of one-way image channels but an active subject of image reproduction in this system. It is expected to be a foundation for a new style of user-centered movie (media based entertainment).

• Journal of Broadcast Engineering
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• v.8 no.4
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• pp.473-480
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• 2003

In this paper, we propose a new quadtree coding a1gorithm to improve the performance of the old one. The new algorithm can process any frame of size in standard and reduce encoding and decoding time by decreasing computational load. It also improves the image quality comparing with any old quantizer based on quadtree and zerotree structure. In order for the new algorithm to be applied for real video codec, we analyze the statistical characteristics of coefficients of differential image and add a function that makes It deal with an arbitrary size of image by using new technique while the old one process by block unit. We can also improve the image quality by scaling the coefficient's value from a differential image. By comparing the performance of the new algorithm with quadtree and SPIHT, it Is shown that PSNR is improved, that the computational load is not reduced in encoding and decoding.

• Journal of Broadcast Engineering
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• v.24 no.6
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• pp.1152-1162
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• 2019

With the rapid development of the VR industry, many VR contents are produced and circulated, and the need for copyright protection is increasing. In this paper, we propose a method of embedding and extracting watermarks in consideration of VR production process. In embedding, SIFT is performed by selecting the region where distortion is minimized in VR production, and transformed into frequency domain using DWT and embedded into the QIM method. In extracting process, in order to correct the distortion in the projection process, the top and bottom regions are changed to different projection methods and some middle regions are rotated using 3DoF to extract the watermark. After this processing, extracted watermark has higher accuracy than the conventional watermark method, and the validity of the proposed watermark is shown by showing that the accuracy is maintained even in various attacks.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.5
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• pp.595-610
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• 1999

This paper presents a visual simulation tool for verification and validation(V&V) of design implications of the Object Behavior Chart developed in accordance with the existing real-time object's behavior design method. This tool can simulates the dynamic interactions using the executable simulation machine, that is EFSM(Extended Finite State Machine) and can detect various logical and temporal errors in the visual object behavior charts before a concrete implementation is made. For this, a LOTOS prototype specification is automatically generated from the visual Object Behavior Chart, and is translated into an EFSM. This system is implemented in Visual C++ version 4.2 and currently runs on PC Windows 95 environment. For simulation purpose, LOTOS was chosen because of it's excellence in specifying communication protocols. Our research contributes to the support tools for seamlessly integrating methodology-based graphical models and formal-based simulation techniques, and also contributes to the automated V&V of the Visual Models.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.70-77
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• 2004

In many industrial applications, an unexpected fault of induction motor drive systems can cause serious troubles such as downtime of the overall system heavy loss, and etc. As one of methods to solve such problems, this paper investigates the fault diagnosis for open-switch damages in a voltage-fed PWM inverter for induction motor drive. For the feature extraction of a fault we transform the current signals to the d-q axis and calculate mean current vectors. And then, for diagnosis of different fault patterns, we propose a clustering based diagnosis algorithm The proposed diagnostic technique is a modified ANFIS(Adaptive Neuro-Fuzzy Inference System) which uses a clustering method on the premise of general ANFIS's. Therefore, it has a small calculation and good performance. Finally, we implement the method for the diagnosis module of the inverter with MATLAB and show its usefulness.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.6
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• pp.55-62
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• 2006

For the fault diagnosis of three-phase induction motors, we construct a experimental unit and then develop a diagnosis algorithm based on pattern recognition. The experimental unit consists of machinery module for induction motor drive and data acquisition module to obtain the fault signal. As the first step for diagnosis procedure, preprocessing is performed to make the acquired current simplified and normalized. To simplify the data, three-phase current is transformed into the magnitude of Concordia vector. As the next step, feature extraction is performed by kernel principal component analysis(KPCA) and linear discriminant analysis(LDA). Finally, we used the classifier based on radial basis function(RBF) network. To show the effectiveness, the proposed diagnostic system has been intensively tested with the various data acquired under different electrical and mechanical faults with varying load.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.239-244
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• 2004

In this paper, we have developed a frequency mixer which can be used as a microwave phase conjugator in the LS band retrodirective antenna system. The mixer as a phase conjugator must have an If signal of which frequency is nearly as high as that of an RF signal, so this fact brings difficulty in the combination of input signals and the design of impedance matching circuit. The circuit configuration is chosen to be of the gate mixer using a pseudomorphic HEMT device. The operating frequencies are 4.00 ㎓, 2.01 ㎓, and 1.99 ㎓ for LO, RF, and IF, respectively. Conversion gain is measured to be 12.5 ㏈ and 1 ㏈ compression point -34 ㏈m at the LO power of -7 ㏈m. The mixer fabricated in this research is the single-ended type, where RF leakage signal appears inevitably at the If port because RF and If frequencies are almost the same. The circuit topology suggested here can be applied directly to the design of balanced-type mixers and phase conjugators.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.486-492
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• 2015

Radiation source imaging system is essential for protecting of radiation leakage accidents and minimizing damages from the radioactive materials, and is expected to play an important role in the nuclear plant decommissioning area. In this study, the stereoscopic camera principle was applied to develop a new radiation imaging device technology that can extract the radiation three-dimensional position information. This radiation three-dimensional imaging device (K3-RIS) was designed as a compact structure consisting of a radiation sensor, a CCD camera, and a pan-tilt only. It features the acquisition of stereoscopic radiation images by position change control, high-resolution detection by continuous scan mode control, and stereoscopic image signal processing. The performance analysis test of K3-RIS was conducted for a gamma-ray source(Cs-137) in radiation calibration facility. The test result showed that a performance error with less than 3% regardless of distances of the objects.