• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.385-386
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• 1996

A wide-field CCD detector for solar eclipse observations is discussed. The CCD is supposed to be of a moderate size, and the image of the corona is obtained by scanning the field of view. Results of the 1995 solar eclipse observation are shown which have been made with a prototype of the scanning CCD detector.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.3
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• pp.34-40
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• 2002

In this paper, a new encryption method for a binary image using Phase modulation and Fourier transform is proposed. For decryption we use the characteristics of square law detector. In encryption process, a key image is obtained by phase modulation of 256 level random pattern and its Fourier transformation, and input image is encrypted by Fourier transforming the multiplication of the phase modulated random pattern and phase modulated input image. The encrypted image and key image have only phase information, so they can not be copied or counterfeited and the original image can not be decrypted without the key image. To reconstruct the original image, each phase mask of the key image and the encrypted image must be placed on each path of the Mach-Zehnder interferometry with Fourier transform lens and the output image is obtained in the form of intensity in the CCD(Charge Coupled Device) camera. The real-time decryption is possible in the proposed system by use of a LCD as a phase modulator and a CCD camera as an intensity detector. The proposed method shows a good performance in the computer simulation and optical experiment as an encryption scheme.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.4
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• pp.471-480
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• 1999

This paper presents design and performance improvement of a new digital tomosynthesis (DTS) system for object-detector synchronous rotation. Firstly, a new DTS system, called OSDR (Object-Detector Synchronous Rotation) is suggested and designed to acquire X-ray digital images. Secondly, the shape distortion of DTS images generated by an image intensifier is modeled. And a new synthesis algorithm, which overcomes the limitations of the existing synthesis algorithm, is suggested to improve the sharpness of the synthesized image. Also an artifact analysis of the DTS system is performed. Thirdly, some performance indices, which evaluate quantitatively performance improvement, are defined. And the experimental verification of the performance improvement is accomplished by the ODSR system newly designed. The advantages of the ODSR system are expressed quantitatively, compared with an existing system.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.1093-1096
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• 1999

In this paper, video image segmentation algorithm based on color histogram and change detector is proposed. Color histograms are calculated from both changed region which is detected in the previous and current frame and unchanged region. With each histogram, modes and valleys are detected. Then, color vectors are calculated by averaging pixels in modes. Markers are extracted by labeling color vectors that represent modes, the watershed algorithm is applied to determine uncertain region. In growing region, the root mean square(RMS) of the distance between average pixel in marker region and adjacent pixel is used as a measure. The proposed algorithm based on color histogram and change detector segments video image fastly and effectively. And simulation results show that the proposed method determines the exact boundary between background and foreground.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.9
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• pp.429-434
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• 2006

In this paper, detection based - adaptive windowed nonlinear filter(DB-AWNF) is proposed for removing salt-pepper noise in infrared image. This filter is composed of impulse detector and window-size-variable median filters. Impulse detector checks whether current pixel is impulse or not using range function and nonlinear location estimator. If impulse is detected, current pixel is filtered according to four kinds of local masks by use of median filter. If not, current pixel is delivered to output like identity filter. In Qualitative view, the proposed could have removed heavy corrupted noise up to 30% and reserved the details of image. In quantitative view, PSNR was measured. The proposed could have about 12-31[dB] more improved performance than those of median $(3{\times}3)$ filter and 13-29[dB] more improved performance than those of median $(5{\times}5)$ filter.

• The KIPS Transactions:PartB
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• v.10B no.1
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• pp.73-80
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• 2003

In this paper we propose an algorithm which matches the corresponding feature points between the reference image and the search image. We use Harris's corner detector to find the feature points in both image. For each feature point in the reference image, we can extract the candidate matching points as feature points in the starch image which the normalized correlation coefficient goes greater than a threshold. Finally we determine a corresponding feature points among candidate points by using dynamic programming. In experiments we show results that match feature points in synthetic image and real image.

• Journal of information and communication convergence engineering
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• v.8 no.3
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• pp.339-342
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• 2010

An iris image pattern positioning with preserved edge detector, ring zone and clock zone, frequency distribution and overlay matching is presented in this paper. Edge detector is required to be powerful and detail. That is proposed by overlaying Canny with LOG (CLOG). The two reference patterns are made from allocating each gray level on the clock zone and ring zone respectively. The normalized target image is overlaid with the clock zone reference pattern and the ring zone pattern to extract overlapped number, and make a matched frequency distribution to look through a symptom and position of human organ and tissue. The iterating experiments result in the ring and clock zone positioning evaluation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.12
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• pp.1742-1745
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• 2019

Hidden flame detection after allegedly extinguishing a fire cannot be emphasized enough. There are a few commercial hidden fire detection equipments which are imported, but the cost is relatively high. In this contribution, we propose a development of a low-cost, high-performance hidden flame detector using open-source hardware/software. We use Raspberry-pi based hardware board equipped with a TFT touch-screen LCD, a 3G modem, and an attachable battery device altogether integrated in a plastic case fabricated with a 3D printer. The proposed hidden flame detector shows the same performance of a commercial product FLIR E5 while consuming less than a half of the cost.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.741-748
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• 2021

In this study, we evaluated image quality by changing collimator length and detector thickness using the Geant4 Application for Tomographic Emission (GATE) simulation tool. The gamma camera based on the Cadimium Zinc Telluride (CZT) and NaI detectors is modeled. In addition the images were acquired by setting 1, 2, 3, 4, 5, and 6 cm collimator length and 1, 3, 5, and 7 mm detector thickness using point source and phantom, which is designed by each diameter (4.45, 3.80, 3.15, 2.55 mm) with 447, 382, 317, and 256 Bq. The sensitivity (cps/MBq) for point source, and signal to noise ratio (SNR) and profile for phantom at the 4.45 mm by drwan the region of interests were used for quantitative analysis. Based on the results, the sensitivity according to collimator length is 2.3 ~ 48.6 cps/MBq for CZT detector, and 1.8 ~ 43.9 cps/MBq for NaI detector. The SNR using phantom is 3.6~9.8 for CZT detector, and 2.9~9.5 for NaI detector. As the collimator length is increased, the image resolution is also improved according to profile results based on the CZT and NaI detector. In addition, the senistivity for detector thickness is 0.04 ~ 0.12 cps/MBq for CZT detector, and 0.03 ~ 0.11 cps/MBq. The SNR using phnatom is 7.3~9.8 count for CZT detector, and 5.9~9.5 for NaI detector. As the detector thickness is increased, the image resolution is decreased according to profile results based on the CZT and NaI detector due to scatter ray. In conclusion, we need to set the geometric material such as detector and collimator to acuquire suitable image quality in nuclear medicine.

• Journal of the Korean Society of Radiology
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• v.3 no.1
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• pp.5-9
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• 2009

The trend of Digital x-ray Detector research is to improve resolution of image and to embody large area imaging as well as dynamic moving imaging, etc. This research is divided with indirect conversion method and direct conversion method by radiation conversion process. Each conversion method has problems such as decrease of resolution from light scattering in indirect method case and not only low system stability but also difficult in dynamic moving imaging in direct method case. X-ray detector using liquid crystal has been researching to solve these problems, but it is difficulty in uniform injection of liquid crystal because of its structural properties. Therefore, this study suggests the structure which solves present problem. Also the possibility of suggested structure was investigated using simulation.