• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.12
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• pp.2586-2594
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• 2009

A digital watermarking technique used as a protection and certifying mechanism of copyrighted creations including music, still images, and videos in terms of finding any loss in data, reproduction and pursuit. This study suggests using a selected geometric invariant point through the whole processing procedure of an image and inserting and extracting based on the invariant point so that it will be robust in a geometric transformation attack. The introduced algorithm here is based on a watershed splitting method in order to make medical images strong against RST(Rotation Scale, Translation) transformation and other processing. It also helps to maintain the watermark in images that are compressed and stored for a period of time. This algorithm also proved that is has robustness against not only JPEG compression attack, but also RST attack and filtering attack.

• Korean Journal of Applied Biomechanics
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• v.31 no.3
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• pp.155-161
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• 2021

Objective: There is a lack of studies using the 3D-2D image registration techniques on the mechanism of a shoulder injury for ice hockey players. This study aimed to analyze in vivo 3D glenohumeral joint arthrokinematics in collegiate ice hockey athletes and compare shoulder scaption with or without a hockey stick using the 3D-2D image registration technique. Method: We recruited 12 male elite ice hockey players (age, 19.88 ± 0.65 years). For arthrokinematic analysis of the common shoulder abduction movements of the injury pathogenesis of ice hockey players, participants abducted their dominant arm along the scapular plane and then grabbed a stick using the same motion under C-arm fluoroscopy with 16 frames per second. Computed tomography (CT) scans of the shoulder complex were obtained with a 0.6-mm slice pitch. Data from the humerus translation distances, scapula upward rotation, anterior-posterior tilt, internal to external rotation angles, and scapulohumeral rhythm (SHR) ratio on glenohumeral (GH) joint kinematics were outputted using a MATLAB customized code. Results: The humeral translation in the stick hand compared to the bare hand moved more anterior and more superior until the abduction angle reached 40°. When the GH joint in the stick hand was at the maximal abduction of the scapula, the scapula was externally rotated 2~5° relative to 0°. The SHR ratio relative to the abduction along the scapular plane at 40° indicated a statistically significant difference between the two groups (p < 0.05). Conclusion: With arm loading with the stick, the humeral and scapular kinematics showed a significant correlation in the initial section of the SHR. Although these correlations might be difficult in clinical settings, ice hockey athletes can lead to the movement difference of the scapulohumeral joints with inherent instability.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.3
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• pp.59-72
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• 2004

In this paper, we classify various attacks that may damage the embedded watermark signal into waveform attack and synchronization attack. And for the specialized defense against the two kinds of attacks we propose a new watermarking scheme named as two layer watermarking method. It consists of a synchronization layer to prepare for the geometrical attack such as rotation and shift and a marking layer 0 embed the watermark signal actually. Namely, the synchronization layer only determines the target region where the watermark signal will be embedded or extracted. And the marking layer spreads the watermark signal over the image as the conventional watermarking methods do. Using the layered structure, the proposed method overcomes the problem that the conventional watermarking methods that do not use the original image at the verification side are most vulnerable to geometrical attacks.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.575-578
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• 2005

Topographical images, in case of aerial or satellite images, are usually similar in colors and textures, and complex in shapes. Thus we have to use shape features of images for efficiently retrieving a query image from topographical image databases. In this paper, we propose a shape feature extraction method which is suitable for topographical images. This method, which improves the existing projection in the Cartesian coordinates, performs the projection operation in the polar coordinates. This method extracts three attributes, namely the number of region pixels, the boundary pixel length of the region from the centroid, the number of alternations between region and background, along each angular direction of the polar coordinates. It extracts the features of complex shape objects which may have holes and disconnected regions. An advantage of our method is that it is invariant to rotation/scale/translation of images. Finally we show the advantages of our method through experiments by comparing it with CSS which is one of the most successful methods in the area of shape feature extraction

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.10
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• pp.1395-1400
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• 2018

EO TGP(Electro-Optical Targeting Pod) is an optical tracking system which has various functions such as target tracking and image stabilization and LOS(Line of Sight) change. Especially, it is very important to move the LOS into a interest point for joystick command. When pilot move joystick in order to observe different scene, EO TGP gimbals should be operated properly. Generally, most EOTS just operate corresponding gimbal for joystick command. For example, if pilot input horizontal command in order to observe right hand screen, it just drive azimuth gimbal at any position. But in the screen, the image dosen't move in a horizontal direction because gimbal structure is Euler angle. And image rotation is occurred by elevation gimbal angle. So we need to move Pitch gimbal. So in the paper, we designed LOS moving algorithm which convert LOS command to gimbal velocity command to move LOS properly. We modeled a differential kinematic equation and then change the joystick command into velocity command of gimbals. This algorithm generate velocity command of each gimbal for same horizontal direction command. Finally, we verified performance through MATLAB/Simulink.

• The KIPS Transactions:PartB
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• v.15B no.2
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• pp.81-86
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• 2008

This paper discusses the problem of partial object recognition in image databases. We propose the method to reconstruct and estimate partially occluded shapes and regions of objects in images from overlapping and cutting. We present the robust method for recognizing partially occluded objects based on symmetry properties, which is based on an ellipse of objects. Our method provides simple techniques to reconstruct occluded regions via a region copy using the symmetry axis within an object. Since our method relies on reconstruction of the object based on the symmetry rather than statistical estimates, it has proven to be remarkably robust in recognizing partially occluded objects in the presence of scale changes, rotation, and viewpoint changes.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.9-12
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• 2015

In this paper, we propose a new feature matching algorithm by modifying and combining the FAST(Features from Accelerated Segment Test) feature detector and SURF feature descriptor which is robust to the distortion of the given image. Scale space is generated to consider the variation of the scale and determine the candidate of features in the image robust to the noise. The original FAST algorithm results in many feature points along edges. To solve this problem, we apply the principal curvatures for refining it. We also use SURF descriptor to make it robust against the variations in the image by rotation. Through the experiments, it is shown that the proposed algorithm has better performance than the conventional feature matching algorithms even though it has much less computational load. Especially, it shows a strength for noisy images.

• Korean Journal of Cognitive Science
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• v.21 no.1
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• pp.145-156
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• 2010

This paper presents a new contents-based digital still image protection method which includes a copyright message. Since the existing method using gradient values used a pixel based $3{\times}3$ Sobel operator, it was sensitive to attacks and could not extract exact copyright message. Therefore, in this paper, we present a algorithm which uses block based OCL(Orientation Certainty Level) instead of pixel. The experimental results show that the proposed scheme not only has good image quality, but also is robust to JPEG lossy compression, filtering, sharpening, blurring and noise. Moreover, the proposed algorithm has good performance more than 10% in rotation attacks than the existing method.

• Journal of the Korean Institute of Landscape Architecture
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• v.29 no.5
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• pp.20-27
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• 2001

The purpose of this study is to investigate and compare the validity and the reliability of the visual simulation method using the internet. For this. the evaluation of the artificial and natural landscape through the medium of color slides are compared with the internet survey. Data is analysed through the comparison of t-test between the two media by landscape type, and spatial image is analysed by factor analysis algorithm. Principle component analysis using Varimax Method is applied for extraction and factor rotation respectively. The results of this study can be summarized as follows; There are no statistical differences between the two methods with artificial and natural landscape in the total data that included second tests. Factors covering the spatial image are found to be \`aesthetic\`, \`spatial shape\`, and \`familiarity\`. Total variance is obtained as 66.4%. There are no statistical differences between the two methods in 2/3 of the cases. In the case of far view of artificial landscape, the results of the t-test show that the two methods are exactly the same. Especially in the case of the artificial far landscape shows no difference of all factors between two methods. There are no differences between first and second tests of the same media and the same landscape type. And it shows the reliability of this method. These results suggest that the probability that the internet can be used as a medium of landscape evaluation and gathering information on anyone\`s landscape image. Simulation techniques with the internet survey method should be further developed for practical application.

• The Journal of Korea Robotics Society
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• v.3 no.2
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• pp.91-98
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• 2008

This paper describes the recognition method of moving objects in mobile robot with an omnidirectional camera. The moving object is detected using the specific pattern of an optical flow in omnidirectional image. This paper consists of two parts. In the first part, the pattern of an optical flow is investigated in omnidirectional image. The optical flow in omnidirectional image is influenced on the geometry characteristic of an omnidirectional camera. The pattern of an optical flow is theoretically and experimentally investigated. In the second part, the detection of moving objects is presented from the estimated optical flow. The moving object is extracted through the relative evaluation of optical flows which is derived from the pattern of optical flow. In particular, Focus-Of-Expansion (FOE) and Focus-Of-Contraction (FOC) vectors are defined from the estimated optical flow. They are used as reference vectors for the relative evaluation of optical flows. The proposed algorithm is performed in four motions of a mobile robot such as straight forward, left turn, right turn and rotation. Experimental results using real movie show the effectiveness of the proposed method.