• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.545-549
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• 1993

an alignment system in the X-and Y-directions an X-Y-.theta. stage driven by piezoelectric actuators is presented. A pair of quadruple gratings and a quadruple photo-detector are used. The difference between the two 0-th order moire signals in reflection with a relative spatial phase of 180.deg. is used in each direction to control the alignment of the X-Y-.theta. stage. The stage is aligned at the position where the difference is zero. The quadruple gratings are 10 mm * 10 mm, and of a binary square-type with a 1/2 duty cycle. Their pitches are 16 .mu.m. Alignment accuracy of .+-.20nm was obtained in this system.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.347-349
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• 2017

This paper reviews the legacy of the SPCIA Coronagraph Instrument (SCI) of which the primary scientific objective is the characterization of Jovian exoplanets by coronagraphic spectroscopy in the infrared. Studies on binary shaped pupil mask coronagraphs are described. Cryogenic active optics is discussed as another key technology. Then approaches to observing habitable zones in exoplanetary systems with a passively-cooled space infrared telescope are discussed. The SCI was dropped in a drastic change of the SPICA mission. However, its legacy is useful for space-borne infrared telescopes dedicated for use in exoplanetary science in the future, especially for studies of biomarkers.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.919-920
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• 2008

In this paper, we present early processing techniques for visual inspection of metallic parts. Since metallic surfaces give rise to specular reflections, it is difficult to extract object boundaries using elementary segmentation techniques such as edge detection or binary thresholding. In this paper, we present two techniques for finding object boundaries on micro bit images. First, we explain a technique for detecting blade boundaries using a directional correlation mask. Second, a line and angle extraction technique based on Harris corner detector and Hough transform is described. These techniques have been effective for detecting blade boundaries, and a number of experimental results are presented using real images.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.258-258
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• 2009

• The Journal of the Korea Contents Association
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• v.2 no.3
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• pp.80-86
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• 2002

In this paper, we propose the new optical security technique using two phase holograms based on interferometer. The encoded random phase image does not have any information on the original image. Without Hewing the key mask, one cannot decode the encrypted image and regenerate the original image. And the use of two phase only images in the proposed security system leads to maximum optical efficiency (100% in theory). Also they cannot be detected by an intensity detector such as a CCD camera. Computer simulations and optical experiments show performance of the proposed methods.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.841-846
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• 2006

A real time system realization for binocular eyeball tracking cursor on the computer monitor screen is presented in the paper. The processing for searching iris and tracking the cursor are that a facial is acquired by the small CCD camera, convert it into binary image, search for the eye two using the five region mask method in the eye surroundings and the side four points diagonal positioning method is searched the each iris. The tracking cursor is matched by measuring the iris central moving position, The cursor controlling is achieved by comparing two related distances between the iris maximum moving and the cursor moving to calculate the moving stance from gazing position and screen. The experimental result are obtained by examining some adults person on the system.

• Communications for Statistical Applications and Methods
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• v.26 no.2
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• pp.79-89
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• 2019

Classification models pertaining to receiver operating characteristic (ROC) curve analysis have been extended from univariate to multivariate setup by linearly combining available multiple markers. One such classification model is the multivariate ROC curve analysis. However, not all markers contribute in a real scenario and may mask the contribution of other markers in classifying the individuals/objects. This paper addresses this issue by developing an algorithm that helps in identifying the important markers that are significant and true contributors. The proposed variable selection framework is supported by real datasets and a simulation study, it is shown to provide insight about the individual marker's significance in providing a classifier rule/linear combination with good extent of classification.

• Korean Journal of Optics and Photonics
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• v.17 no.3
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• pp.231-239
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• 2006

In recent years, a hierarchical security architecture has been widely studied because it can efficiently protect information by allowing an authorized user access to the level of information. However, the conventional hierarchical decryption methods require several decryption keys for the high level information. In this paper, we propose a hierarchical image encryption using random phase masks and Walsh code having orthogonal characteristics. To decrypt the hierarchical level images by only one decryption key, we combine Walsh code into the hierarchical level system. For encryption process, we first perform a Fourier transform for the multiplication results of the original image and the random phase mask, and then expand the transformed pattern to be the same size and shape of Walsh code. The expanded pattern is finally encrypted by multiplying with the Walsh code image and the binary phase mask. We generate several encryption images as the same encryption process. The reconstruction image is detected on a CCD plane by a despread process and Fourier transform for the multiplication result of encryption image and hierarchical decryption keys which are generated by Walsh code and binary random phase image. Computer simulations demonstrate that the proposed technique can decrypt hierarchical information by using only one level decryption key image and it has a good robustness to the data loss such as random cropping.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.353-364
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• 2002

In this paper, a new onto-digital stereo object-tracking system using hierarchical digital algorithms and optical BPEJTC is proposed. This proposed system can adaptively track a moving target by controlling the convergence of stereo camera. firstly, the target is detected through the background matching of the sequential input images by using optical BPEJTC and then the target area is segmented by using the target projection mask which is composed by hierarchical digital processing of image subtraction, logical operation and morphological filtering. Secondly, the location's coordinate of the moving target object for each of the sequential input frames can be extracted through carrying out optical BPEJTC between the reference image of the target region mask and the stereo input image. Finally, the convergence and pan/tilt of stereo camera can be sequentially controlled by using these target coordinate values and the target can be kept in tracking. Also, a possibility of real-time implementation of the adaptive stereo object tracking system is suggested through optically implementing the proposed target extraction and convergence control algorithms.

• Journal of Korea Multimedia Society
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• v.12 no.2
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• pp.191-199
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• 2009

In this paper, the improved edge extract methods is proposed in order to extract edge. For the correct and fast detect, the binary image using the threshold value is applied for a experiment. For the experimental analysis, we compare the existing edge methods with the improved methods. Hereby, the exist methods are the sobel, robert, and prewitt. and the improved methods use the existing methods which is applied mask variations. The merits of the improved mothods have a result of a little erosion, a apparent edge. Specially, we use the grey image of medical image for the experimental analysis and then apply threshold value for a result image. After that, we acquire a apparent edge. For a quantitative analysis of the each methods, the each images was applied a histogram. As a result, we prove the merit of the improved methods using a analytical graph of the medical images.