• The Journal of the Acoustical Society of Korea
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• v.15 no.1
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• pp.54-60
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• 1996

In most pattern recognition and image understanding applications, images are degraded by noise and other distortions. Therefore, it is more relevant to decide how similar two objects are rather than to decide whether the two are exactly the same. In this paper, we propose a method for recognizing degraded symbols using a distance measure between two graphs representing the symbols. a symbol is represented as a graph consisting of nodes and edges based on the run graph concept. The graph is then transformed into a reference model graph with production rule containing the embedding transform. The symbols are recognized by using the distance measure which is estimated by using the number of production rules used and the structural homomorphism between a transformed graph and a model graph. the proposed approach is applies to the recognition of non-note musical symbols and the result are given.

• Korean Journal of Digital Imaging in Medicine
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• v.14 no.2
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• pp.57-61
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• 2012

To compare the accuracy of breath-hold magnetic resonance imaging sequences to establish the most effective superparamagnetic iron oxide-enhanced sequence for detection of hepatic metastases. A total of 100 patients(50men and 50women, mean age: 60years) with liver disease(including malignant and benign liver lesions) were investigated at 3.0T machine (GE, General Electric Medical System, Excite HD) with 8Ch body coil. Pulse sequence for MR imaging decided to the FS-T2-FSE-RT(TR/TE/Thick./Freq./Phase=12857ms/100ms/7mm/512/384), MGRE(TR/TE/Thick./Freq./Phase=100ms/9.7ms/7mm/384/288), in-out of phase echo(TR/$TE_1$, $TE_2$/Thick./Freq./Phase=140ms/2.4, 5.8ms/7mm/352/300), Images obtained before the injection of SPIO. Six sequences were optimized for lesion detection: FS-T2-FSE-RT, multigradient recalled echo data image(MGRE), T2-weighted MGRE with an 9.7msec echo time. Images were reviewed independently by five blinded observers. The accuracy of each sequence was measured by using picture archiving communication system analysis. All results were correlated with findings at multidectator computed tomography examination. Differences between the mean results of the six observers were measured by using paired student t-test analysis. Postcontrast T2-weighted MGRE sequences were the most accurate and were significantly superior to postcontrast FS-T2-FSE-RT, T2-weighted MGRE, in-out of phase MR sequences(p < .05). For all lesions that were malignant or smaller than 1 cm, respectively, contrast to noise ratio of pre and postcontrast sequences were -1and -0.3 for T2-weighted FSE, 0.53 and 4.5 in-out of phase, 7, 7.08, 5.08, 3.32, 1.7, 1.16, 0.79, 0.68 for GRE with 2.9, 7.5, 12.1, 16.6, 21.2, 25.8, 30.4, 35.0 TE values. Breath-hold various TE precontrast sequences offer improvement in sensitivity compared with fixed multigradient recalled echo sequences alone.

• The Journal of the Korea Contents Association
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• v.5 no.6
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• pp.343-350
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• 2005

During the design of a successful digital watermarking systems, Pseudo-Noise(PN) sequences are widely used to modulate information bits into watermark signals. In this method, the number of bits that can be hidden within a small image by means of frequency domain watermarking is limited. In this paper, we show the possibility of introducing chaotic sequences into digital watermarking systems as potential substitutes to commonly used PN-sequences. And we propose a method that transforms the text to chaotic sequence. In our current implementation, we show how the sample text is expressed by an implied unit data(watermark) and the implied unit data is regenerated into the original left. Because we use this implied data as watermark for information hiding, we can insert much more watermark compared with previous method.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.57-62
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• 2012

The purpose of this paper is to find dangerous factors of a water purifier when water leaks due to inappropriate use and analyze the patterns of damaged parts in order to provide data for the examination of the cause of the problem. If the water purifier is inspected and managed by a non-specialist, when the FLC(Float Level Controller) at the top is inclined, water leakage may occur to the water purifier. The leaked water flows onto the cables and hoses and enters the thermostat terminal, heater, PCB, power supply connection connector, etc., becoming a dangerous factor that may cause a system failure, fire, etc. Due to the water that entered the input terminal, low noise and white smoke were generated at first. However, the flame gradually propagated due to the continuous inflow of moisture. It was found that when moisture reached the PCB, a carbonized conductive path was formed at the varistor terminal, input terminal, semiconductor device terminal, etc., and the flame became larger, which might result in a fire. From the metal microscope analysis of a damaged condenser terminal, it was found that the amorphous structure unique to copper cable disappeared, and voids, boundary surface and disorderly fine particles occurred. Also, in the case of the connector into which moisture penetrated, fusion and deformation occurred at the cable connection clips. The result of analysis of the power supply cable connector using a thermal image camera showed that most of the heat was generated from the cable connection clips and the temperature at the connection center was normal.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.3
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• pp.237-246
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• 2001

A high speed context-free marker-controlled and minima imposition-free watershed transform is proposed for efficient multi-object detection and segmentation from a complex background. The context-free markers are extracted from a complex backgrounded multi-object image using a noise tolerant attention operator. These make marker-controlled watershed possible for the over-segmentation reduction without region merging. The proposed method presents a marker-constrained labeling that can speed up the segmentation of a marker-controlled watershed transform by eliminating the necessity of the minima imposition. Simulation results show that the proposed method can efficiently detects and segments multiple objects from a complex background while reducing over- segmentation and the computation time.

• Nuclear Engineering and Technology
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• v.49 no.4
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• pp.776-780
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• 2017

To avoid imaging artifacts and interpretation mistakes, an improvement of the uniformity in gamma camera systems is a very important point. We can expect excellent uniformity using cadmium zinc telluride (CZT) photon counting detector (PCD) because of the direct conversion of the gamma rays energy into electrons. In addition, the uniformity performance such as integral uniformity (IU), differential uniformity (DU), scatter fraction (SF), and contrast-to-noise ratio (CNR) varies according to the energy window setting. In this study, we compared a PCD and conventional scintillation detector with respect to the energy windows (5%, 10%, 15%, and 20%) using a $^{99m}Tc$ gamma source with a Geant4 Application for Tomography Emission simulation tool. The gamma camera systems used in this work are a CZT PCD and NaI(Tl) conventional scintillation detector with a 1-mm thickness. According to the results, although the IU and DU results were improved with the energy window, the SF and CNR results deteriorated with the energy window. In particular, the uniformity for the PCD was higher than that of the conventional scintillation detector in all cases. In conclusion, our results demonstrated that the uniformity of the CZT PCD was higher than that of the conventional scintillation detector.

• Journal of the Korea Society of Computer and Information
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• v.10 no.3 s.35
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• pp.173-182
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• 2005

In this paper, we propose a landmark recognition method which is irrelevant to the camera viewpoint on the navigation for localization. Features in previous research is variable to camera viewpoint, therefore due to the wealth of information, extraction of visual landmarks for positioning is not an easy task. The proposed method in this paper, has the three following stages; first, extraction of features, second, learning and recognition, third, matching. In the feature extraction stage, we set the interest areas of the image. where we extract the corner points. And then, we extract features more accurate and resistant to noise through statistical analysis of a small eigenvalue. In learning and recognition stage, we form robust feature models by testing whether the feature model consisted of five corner points is an invariant feature irrelevant to viewpoint. In the matching stage, we reduce time complexity and find correspondence accurately by matching method using similarity evaluation function and Graham search method. In the experiments, we compare and analyse the proposed method with existing methods by using various indoor images to demonstrate the superiority of the proposed methods.

• Journal of the Korea Society of Computer and Information
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• v.12 no.1 s.45
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• pp.57-65
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• 2007

In the fast block matching algorithm. search patterns of different shapes or sizes and the distribution of motion vectors have a large impact on both the searching speed and the image qualify. In this paper, we propose a new fast block matching algorithm using the flat-hexagon search pattern that ate solved disadvantages of the diamond pattern search algorithm(DS) and the hexagon-based search algorithm(HEXBS). Our proposed algorithm finds mainly the motion vectors that not close to the center of search window using the flat-hexagon search pattern. Through experiments, compared with the DS and HEXBS, the proposed f)at-hexagon search algorithm(FHS) improves about $0.4{\sim}21.3%$ in terms of average number of search point per motion vector estimation and improves about $0.009{\sim}0.531dB$ in terms of PSNR(Peak Signal to Noise Ratio).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4C
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• pp.217-225
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• 2011

In this paper, we propose an adaptive de-interlacing algorithm that is based on the degree of local complexity. The conventional intra field de-interlacing algorithms show the different performance according to the ways which find the edge direction. Furthermore, FDD (Fine Directional De-interlacing) algorithm has the better performance than other algorithms but the computational complexity of FDD algorithm is too high. In order to alleviate these problems, the proposed algorithm selects the most efficient de-interacing algorithm among LA (Line Average), MELA (Modified Edge-based Line Average), and LCID (Low-Complexity Interpolation Method for De-interlacing) algorithms which have low complexity and good performance. The proposed algorithm is trained by the DoLC (Degree of Local Complexity) for selection of the algorithms mentioned above. Simulation results show that the proposed algorithm not only has the low complexity but also performs better objective and subjective image quality performances compared with the conventional intra-field methods.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.3
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• pp.278-284
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• 2010

In this paper, a millimeter-wave detector using zero-bias schottky diode is designed and fabricated at W-band. It consists of LNA(Low Noise Amplifier) and detector module to improve sensitivity. LNA case with a highly stop-band characteristic is designed to prevent the oscillation by LNA MMIC chip. Diode detector of planar structure is fabricated for the easy connection with LNA module and zero bias Schottky diode is utilized. In practice, the fabricated diode detector have shown the detection voltage of 20~500 mV to the RF input power of -45~-20 dBm. The proposed W-band detector can be applicable to the passive millimeter image system.