• Korean Journal of Radiology
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• 제23권9호
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• pp.847-852
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• 2022

• Journal of Biomedical Engineering Research
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• 제25권2호
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• pp.97-102
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• 2004

We developed an x-ray cone-beam micro computed tomography (micro-CT) system for small-animal imaging. The micro-CT system consists of a 2-D flat-panel x-ray detector with a field-of-view (FOV) of 120${\times}$120 mm2, a micro-focus x-ray source, a scan controller and a parallel image reconstruction system. Imaging performances of the micro-CT system have been evaluated in terms of contrast and spatial resolution. The minimum resolvable contrast has been found to be less than 36 CT numbers at the dose of 95 mGy and the spatial resolution about 14 lp/mm. As small animal imaging results, we present high resolution 3-D images of rat organs including a femur, a heart and vessels. We expected that the developed micro-CT system can be greatly used in biomedical studies using small animals.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.17-18
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• 2008

• Journal of information and communication convergence engineering
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• 제5권2호
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• pp.136-139
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• 2007

In this paper we will discuss a general idea about an information system which provides information a user really needs in user's authentication. We will discuss how RFID could be applied for this kind of system especially from the standpoint of using RFID as a way to collect information of personal belongings. Also we will discuss security issues of using RFID as a component of the proposed system because while RFID could provide usefulness, it could also be very dangerous for revealing private information without user's awareness.

• Journal of Biomedical Engineering Research
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• 제9권1호
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• pp.125-130
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• 1988

In the conventional infrared imaging system, complex infrared lens systems are usually used for directing collimated narrow infrared beams into the high speed 2-dimensional optic scanner. In this paper, a simple reflective infrared optic system with a 2-dimensional optic scanner is proposed for the realization of medical infrared thermography system. It has been experimentally proven that the intfrared thermography system composed of the proposed optic system has the temperature resolution of $0.1^{\circ}C$ under the spatial resolution of lmrad, the image matrix size of $256 {\times} 240, $ and tile imaging time of 4 seconds.

• Journal of information and communication convergence engineering
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• 제12권4호
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• pp.208-214
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• 2014

In this paper, in order to solve the problems of a narrow viewing angle and the flip effect in a three-dimensional (3D) integral imaging display, we propose an improved system by using an eye tracking method based on the Kinect sensor. In the proposed method, we introduce two types of calibration processes. First process is to perform the calibration between two cameras within Kinect sensor to collect specific 3D information. Second process is to use a space calibration for the coordinate conversion between the Kinect sensor and the coordinate system of the display panel. Our calibration processes can provide the improved performance of estimation for 3D position of the observer's eyes and generate elemental images in real-time speed based on the estimated position. To show the usefulness of the proposed method, we implement an integral imaging display system using the eye tracking process based on our calibration processes and carry out the preliminary experiments by measuring the viewing angle and flipping effect for the reconstructed 3D images. The experimental results reveal that the proposed method extended the viewing angles and removed the flipping images compared with the conventional system.

• The Journal of Korea Robotics Society
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• 제10권3호
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• pp.146-153
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• 2015

In order to contain as much information as possible in a single image, a wide FOV(Field-Of-View) imaging system is required. The catadioptric imaging system with hyperbolic cylinder mirror can acquire over 180 degree horizontal FOV realtime panorama image by using a conventional camera. Because the hyperbolic cylinder mirror has a curved surface in horizontal axis, the original image acquired from the imaging system has the geometrical distortion, which requires the image processing algorithm for reconstruction. In this paper, the image reconstruction algorithms for two cases are studied: (1) to obtain an image with uniform angular resolution and (2) to obtain horizontally rectilinear image. The image acquisition model of the hyperbolic cylinder mirror imaging system is analyzed by the geometrical optics and the image reconstruction algorithms are proposed based on the image acquisition model. To show the validity of the proposed algorithms, experiments are carried out and presented in this paper. The experimental results show that the reconstructed images have a uniform angular resolution and a rectilinear form in horizontal axis, which are natural to human.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.817-820
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• 2002

Amorphous selenium based flat panel detectors convert incident x-ray to electric signal directly. Flat panel detectors gain more interest real time medical x-ray imaging. TFT array and electric readout circuits are used in this paper offered by LG.Philips.LCD. Detector is based on a $1536{\times}1280$ array of a-Si TFT pixels. X-ray conversion layer(a-Se) is deposited upper TFT array with a $400{\mu}m$ by thermal deposition technology. Thickness uniformity of this layer is made of thickness control system technology$({\leq}5%)$. Each $139{\mu}m{\times}139{\mu}m$ pixel is made of thin film transistor technology, a storage capacitor and collecting electrode having geometrical fill factor of 86%. This system show dynamic performance. Imaging performance is suited for digital radiography imaging substitute by conventional radiography film system.

• Journal of the Optical Society of Korea
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• 제20권3호
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• pp.381-388
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• 2016

The performance of a staring infrared imaging system can be characterized based on estimating the modulation transfer function (MTF). The slant edge method is a widely used MTF estimation method, which can effectively solve the aliasing problem caused by the discrete undersampling of the infrared focal plane array. However, the traditional slant edge method has some limitations such as the low precision of the edge angle extraction and using the approximate function to fit the edge spread function (ESF), which affects the accuracy of the MTF estimation. In this paper, we propose a modified slant edge method, including an edge angle extraction method that can improve the precision of the edge angle extraction and an ESF fitting algorithm which is based on the transfer function model of the imaging system, to enhance the accuracy of the MTF estimation. This modified slant edge method presents higher estimation accuracy and better immunity to noise and edge angle than other traditional methods, which is demonstrated by the simulation and application experiments operated in our study.

• Current Optics and Photonics
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• 제5권6호
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• pp.686-698
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• 2021

A camouflaged encryption scheme based on Hadamard matrix and ghost imaging is proposed. In the process of the encryption, an orthogonal matrix is used as the projection pattern of ghost imaging to improve the definition of the reconstructed images. The ciphertext of the secret image is constrained to the camouflaged image. The key of the camouflaged image is obtained by the method of sparse decomposition by principal component orthogonal basis and the constrained ciphertext. The information of the secret image is hidden into the information of the camouflaged image which can improve the security of the system. In the decryption process, the authorized user needs to extract the key of the secret image according to the obtained random sequences. The real encrypted information can be obtained. Otherwise, the obtained image is the camouflaged image. In order to verify the feasibility, security and robustness of the encryption system, binary images and gray-scale images are selected for simulation and experiment. The results show that the proposed encryption system simplifies the calculation process, and also improves the definition of the reconstructed images and the security of the encryption system.