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Watermark Algorithm Using Difference Matrix between Successive Blocks (연속 블록간의 화소차이 행렬을 이용한 워터마크 알고리즘)

  • Park, Ki-Hong;Kim, Yoon-Ho
    • Journal of Advanced Navigation Technology
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    • v.12 no.3
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    • pp.273-279
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    • 2008
  • In this paper, we proposed a watermarking algorithm by using difference matrix between successive blocks in the transform domain. In the preprocessing, original image is decomposed with 1-level sub-bands by DWT. Then, all sub-bands which are excepted the low-frequency bands are set to normalize and make a reference image after transforming inverse DWT. The statistic variance of successive blocks between the original image and the reference image are calculated and finally, watermark is embedded considering the local characteristic with respect to the high-frequence components. Experimental results showed that the proposed approach is robust and better invisible in such attacks as filtering, JPEG and noise addition.

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Efficient Object-based Image Retrieval Method using Color Features from Salient Regions

  • An, Jaehyun;Lee, Sang Hwa;Cho, Nam Ik
    • IEIE Transactions on Smart Processing and Computing
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    • v.6 no.4
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    • pp.229-236
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    • 2017
  • This paper presents an efficient object-based color image-retrieval algorithm that is suitable for the classification and retrieval of images from small to mid-scale datasets, such as images in PCs, tablets, phones, and cameras. The proposed method first finds salient regions by using regional feature vectors, and also finds several dominant colors in each region. Then, each salient region is partitioned into small sub-blocks, which are assigned 1 or 0 with respect to the number of pixels corresponding to a dominant color in the sub-block. This gives a binary map for the dominant color, and this process is repeated for the predefined number of dominant colors. Finally, we have several binary maps, each of which corresponds to a dominant color in a salient region. Hence, the binary maps represent the spatial distribution of the dominant colors in the salient region, and the union (OR operation) of the maps can describe the approximate shapes of salient objects. Also proposed in this paper is a matching method that uses these binary maps and which needs very few computations, because most operations are binary. Experiments on widely used color image databases show that the proposed method performs better than state-of-the-art and previous color-based methods.

Assessment of Gradient-based Digital Speckle Correlation Measurement Errors

  • Jian, Zhao;Dong, Zhao;Zhe, Zhang
    • Journal of the Optical Society of Korea
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    • v.16 no.4
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    • pp.372-380
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    • 2012
  • The optical method Digital Speckle Correlation Measurement (DSCM) has been extensively applied due its capability to measure the entire displacement field over a body surface. A formula of displacement measurement errors by the gradient-based DSCM method was derived. The errors were found to explicitly relate to the image grayscale errors consisting of sub-pixel interpolation algorithm errors, image noise, and subset deformation mismatch at each point of the subset. A power-law dependence of the standard deviation of displacement measurement errors on the subset size was established when the subset deformation was rigid body translation and random image noise was dominant and it was confirmed by both the numerical and experimental results. In a gradient-based algorithm the basic assumption is rigid body translation of the interrogated subsets, however, this is in contradiction to the real circumstances where strains exist. Numerical and experimental results also indicated that, subset shape function mismatch was dominant when the order of the assumed subset shape function was lower than that of the actual subset deformation field and the power-law dependence clearly broke down. The power-law relationship further leads to a simple criterion for choosing a suitable subset size, image quality, sub-pixel algorithm, and subset shape function for DSCM.

Matching Performance Analysis of Upsampled Satellite Image and GCP Chip for Establishing Automatic Precision Sensor Orientation for High-Resolution Satellite Images

  • Hyeon-Gyeong Choi;Sung-Joo Yoon;Sunghyeon Kim;Taejung Kim
    • Korean Journal of Remote Sensing
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    • v.40 no.1
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    • pp.103-114
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    • 2024
  • The escalating demands for high-resolution satellite imagery necessitate the dissemination of geospatial data with superior accuracy.Achieving precise positioning is imperative for mitigating geometric distortions inherent in high-resolution satellite imagery. However, maintaining sub-pixel level accuracy poses significant challenges within the current technological landscape. This research introduces an approach wherein upsampling is employed on both the satellite image and ground control points (GCPs) chip, facilitating the establishment of a high-resolution satellite image precision sensor orientation. The ensuing analysis entails a comprehensive comparison of matching performance. To evaluate the proposed methodology, the Compact Advanced Satellite 500-1 (CAS500-1), boasting a resolution of 0.5 m, serves as the high-resolution satellite image. Correspondingly, GCP chips with resolutions of 0.25 m and 0.5 m are utilized for the South Korean and North Korean regions, respectively. Results from the experiment reveal that concurrent upsampling of satellite imagery and GCP chips enhances matching performance by up to 50% in comparison to the original resolution. Furthermore, the position error only improved with 2x upsampling. However,with 3x upsampling, the position error tended to increase. This study affirms that meticulous upsampling of high-resolution satellite imagery and GCP chips can yield sub-pixel-level positioning accuracy, thereby advancing the state-of-the-art in the field.

The Effects of CO2 Enrichment on the Radial Growth of Pinus densiflora

  • En-Bi CHOI;Hyemin LIM;Jeong-Wook SEO
    • Journal of the Korean Wood Science and Technology
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    • v.52 no.3
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    • pp.289-299
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    • 2024
  • The current study aimed to investigate the impact of CO2 enrichment on the width of annual tree rings, earlywood and latewood, and the area of annual growth of Pinus densiflora Siebold & Zucc. grown in open-top chamber (OTC). To this end, two CO2 enrichment cases were considered, namely 1.4 × increment (560 ppm in OTC-II) and 1.8 × (720 ppm in OTC-III) were compared with the current atmosphere (400 ppm in OTC-I). The CO2 enrichment conditions for a period of 12 years (2010-2021) were considered, and all measurements were done through image analysis. The study showed that the increment in CO2 concentrations positively affected the tree growth. The measurement data from the trees in OTC-III were considerably higher than those from OTC-I, whereas those from OTC-II were slightly higher than those from OTC-I. Decreasing patterns of the measured widths and area in 6-7 years after the beginning of CO2 enrichment was found for all the OTCs. These patterns were possibly due to changes in the physiological features, such as aging. The findings of the present study can have potential uses as fundamental data for forest management considering CO2 concentrations.

A Study of Waveform Inversion for Improvement of Sub-Salt Migration Image (암염돔 하부 구조의 구조보정 영상 개선을 위한 파형역산 기법 연구)

  • Ha, Wan-Soo;Pyun, Suk-Joon;Son, Woo-Hyun;Shin, Chang-Soo;Ko, Seung-Won;Seo, Young-Tak
    • Geophysics and Geophysical Exploration
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    • v.11 no.3
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    • pp.177-183
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    • 2008
  • The sub-salt imaging technique becomes more crucial to detect the hydro-carbonates in petroleum exploration as the target reservoirs get deeper. However, the weak reflections from the sub-salt structures prevent us from obtaining high fidelity sub-salt image. As an effort to overcome this difficulty, we applied the waveform inversion by implementing multi-grid technique to the sub-salt imaging. Through the comparison between the conventional waveform inversion using fixed grid and the multi-grid technique, we confirmed that the waveform inversion using multi-grid technique has advantages over the conventional fixed grid waveform inversion. We showed that the multi-grid technique can complement he velocity estimation result of the waveform inversion for imaging the sub-salt structures, of which velocity model cannot be obtained correctly by the conventional fixed grid waveform inversion.

Effectiveness of CO2 Fractional Laser on Linear Scars in Children

  • Ji, So young;Lee, Wu Seop;Yang, Wan Suk;Kim, Yong-Min;Baik, Bong Soo
    • Medical Lasers
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    • v.8 no.1
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    • pp.1-6
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    • 2019
  • Background and Objectives A facial laceration is a commonly occurring trauma of children. In addition, appropriate treatment and scar management are very important because the psychosocial impact of facial scars is much greater in children than in adults. Materials and Methods In the authors' hospital, primary closure was conducted targeting a total of 8,924 patients from January 2015 to December 2017. Of these, scar management was conducted on 808 people using a CO2 fractional laser and Q-Switch Nd:YAG laser. To prove the effectiveness of the laser treatment on the linear scar, the patients were divided retrospectively into children and adults and sub-divided into those who received the treatment and those who did not. The subjective satisfaction of patients was evaluated using the Numeric Rating System (NRS). The objective scar scoring was evaluated using the image panel assessment based on the Vancouver Scar Scale (VSS), and the scoring was made by averaging the evaluations of three plastic surgeons. Results Evaluated NRS showed 8.50 ± 1.83 for adults without a laser, 8.51 ± 1.47 for adults with a laser, 7.93 ± 2.10 for children without a laser, and 8.9 ± 1.24 for children with a laser. The image panel assessment revealed 7.06 ± 1.31 for adults without a laser, 6.40 ± 2.37 for adults with a laser, 6.86 ± 1.45 for children without a laser, and 5.93 ± 1.21 for children with a laser. Conclusion When the linear scar is managed using a CO2 Fractional laser, it can be managed in children better than adults, which is believed to be useful because it leads to better satisfaction and prognosis.

A Study on the Estimation of Lane position using difference of Intensity (Intensity차를 이용한 차선의 위치 검출에 관한 연구)

  • 손경희;송현승;노도환
    • 제어로봇시스템학회:학술대회논문집
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    • 2000.10a
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    • pp.403-403
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    • 2000
  • Generally estimation of driving direction uses the way which uses lane detection and vanishing point in autonomous-driving system. Especially we use Sub-window for decreasing Process time when we detect lane, but fixed sub-window can not detect lane because of some factors in road image. So we suggest algorithm using one-dimension line scan method to detect an exact position of lane.

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A Study on the Diagnostic Reference Level of Skull Radiography in Digital Radiography (디지털 방사선 환경에서 두부 방사선검사 시 진단참고수준 검사조건에 대한 고찰)

  • Yeon-Jin, Jeong;Young-Cheol, Joo;Dong-Hee, Hong;Sang-Hyeon, Kim
    • Journal of the Korean Society of Radiology
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    • v.16 no.7
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    • pp.897-904
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    • 2022
  • The purpose of this study is to compare the difference in dose and image quality when applying the diagnostic reference level (DRL) test conditions for head radiography in a digital radiation environment and the test conditions currently applied in clinical practice. I would like to review the conditions of radiographic examination. In this study, the head model phantom was targeted, and the investigation conditions were divided into clinical conditions (Clinic), DRL value (DRL75), and DRL average value (DRLmean). For dose, Enterance surface dose (ESD) was measured, and for image quality, signal-to-noise ratio and contrast-to-noise ratio were measured and analyzed for comparison. The average values of skull anterior posterior(AP) ESD according to the changes in test conditions were Clinic 1214.03±4.21 µGy, DRL75 3017.83±8.14 µGy, DRLmean 2283.50±7.09 µGy, and skull lateral (Lat). The average value of ESD was statistically significant with Clinic 762.79±3.54 µGy, DRL75 2168.57±10.83 µGy, and DRLmean 1654.43±6.48 µGy (p<0.01). The average values of SNR and CNR measured in the orbital, maxillary sinus, frontal sinus, and sella turcica were statistically significant (p<0.01). As a result of this study, compared to DRL, the conditions used in clinical practice showed lower dose levels of about 58% for AP and about 70% for Lat., and there was no qualitative difference in terms of image quality. Through this study, it is necessary to consider a new diagnostic reference level suitable for the digital radiation environment, and it is considered that the dose should be reduced accordingly.

Effect of Calcination Temperatures on the Structure and Electrochemical Characterization of Li(Ni0.5Mn0.3Co0.2)O2 as Cathode Material by Supercritical Hydrothermal Synthesis Method (초임계 수열법으로 합성한 Li(Ni0.5Mn0.3Co0.2)O2 양극 활물질의 소성 온도영향에 따른 구조 및 전기화학적 특성)

  • Choo, Soyeon;Beom, YunGyeong;Kim, Sungsu;Han, Kyooseung
    • Journal of the Korean Electrochemical Society
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    • v.16 no.3
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    • pp.151-156
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    • 2013
  • As the cathode material for li-ion battery, $LiNi_{0.5}Mn_{0.3}Co_{0.2}O_2$ were synthesized by supercritical hydrothermal method and calcined $850^{\circ}C$ and $900^{\circ}C$ for 10hrs in air. The effect of temperature in the heat treatment on the powder and its performance were studied of xray diffraction pattern, SEM-image, physical properties and electrochemical behaviors. As a result, calcined at $900^{\circ}C$ material particle size more increase than calcined at $850^{\circ}C$ material, especially shows excellent electrochemical performance with initial reversible specific capacity of 163.84 mAh/g (0.1C/2.0-4.3V), 186.87 mAh/g (0.1C/2.0-4.5V) and good capacity retention of 91.49% (0.2C/2.0-4.3V) and 90.36% (0.2C/2.0-4.5V) after 50th charge/discharge cycle.