• Journal of the Optical Society of Korea
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• v.20 no.4
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• pp.476-480
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• 2016

For the application of multiusers, the arrangement and distribution of the keys is a much concerning problem in a cryptosystem. In this paper, we propose an optical encryption scheme with multiple users based on computational ghost imaging (CGI) and orthogonal modulation. The CGI encrypts the secret image into an intensity vector rather than a complex-valued matrix. This will bring convenience for post-processing and transmission of the ciphertext. The orthogonal vectors are taken as the address codes to distinguish users and avoid cross-talk. Only the decryption key and the address code owned by an authorized user are matched, the secret image belonging to him/her could be extracted from the ciphertext. Therefore, there are two security levels in the encryption scheme. The feasibility and property are verified by numerical simulations.

• Journal of Biomedical Engineering Research
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• v.32 no.2
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• pp.85-92
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• 2011

Bioluminescence imaging (BLI) is the most sensitive animal imaging technique for molecular imaging research. Generally, highly sensitive CCD is used to detect an optical probe introduced in a living mouse. However, in many cases, the light signal emitted from a probe is too small to detect because it is scattered and attenuated by the tissue prior to being detected. The problem is that scattering and attenuation not only inhibit accurate measurement but also make image quality down. Thus we introduced a new method to reduce noise by using property of CCD and method to improve image quality of bioluminescence image by using two steps Gaussian blurring.

• Korean Journal of Digital Imaging in Medicine
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• v.12 no.1
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• pp.19-25
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• 2010

This study is mainly for the reduction of exposure dose by using a heavy elements filter(Gd) in the digital radiology. They contained heavy elements filter of Gd and X-ray beam hardening filters such as Al and Cu. According to the results of experimental evaluation, X-ray property was not changed with variety of kVp in the case of the Gd filter. The surface dose and absorption dose were increased in order of Cu and Al. The contrast of image showed the higher value in order of Cu, Al and Gd. While the use of Gd has increased the numerical value of the CR image, and grayscale has decreased noise value of the DR image.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.187-190
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• 2001

A new ultrasound imaging technique based on simultaneous multiple transmit focusing using orthogonal modified Golay codes is presented. modified Golay codes are used to increase signal-to-noise-ratio(SNR) and maximize the transmit power efficiency(TPE). Conventional Golay codes consist of a pair of complementary codes with same length and can be compressed into a delta-like signal due to their complementary property. In the present work, two modified Golay codes focused at different depths are transmitted at the same time, which are mutually orthogonal. On receive, these orthogonal modified Golay codes are separately compressed into two short pulses and individually focused. These two focused beam are combined to form a frame of image with improved lateral resolution. Computer simulations are performed to verity the proposed method improves the lateral resolution of image compared with the conventional echo system.

• KSTLE International Journal
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• v.7 no.1
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• pp.10-13
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• 2006

In this work, imaging and study of elastic property of the living cell was performed. The motivation of this work was to seek the possibility of exploiting Young's modulus as a disease indicator using Atomic Force Microscope (AFM) and also to gain fundamental understanding of cell mechanics for applications in medical nanorobots of the future. L-929 fibroblast adherent cell was used as the sample. Imaging condition in cell culturing media environment was done in very low speed ($20{\mu}m/ s$) compared to that in the ambient environment. For measuring the Young's modulus of the living cell, AFM indentation method was used. From the force-distance curve obtained from the indentation experiment the Young's modulus could be derived using the Hertz model. The Young's modulus of living L-929 fibroblast cell was $1.29{\pm}0.2$ kPa.

• Korean Journal of Optics and Photonics
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• v.18 no.2
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• pp.111-116
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• 2007

A high power LED which is being used in many illumination applications as a new light source was simulated for its physical structure and then its optical properties were analyzed. To obtain accurate results from the designed LED model, properties of the die chip and reflector cup were varied. As a result, a high power LED model which has a radiation pattern of a Lambertian with its viewing angle of approximately $140^{\circ}$ and total included angle of $160^{\circ}$ was designed.

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.4
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• pp.185-189
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• 2011

To assess the prevalence of various radiological reduction methods for childhood intussusception in training hospitals by means of a nationwide phone survey, and to demonstrate recent trends in this area by comparing the findings with those obtained in a survey conducted. $BaTiO_3$ system was prepared by using fabrication of classical conditioning ceramics. Polycrystalline and surface structure characteristics of the specimens were measured by X-ray diffraction, SEM(Scanning Electron Microscopy) and EDAX (Energy Dispersive Spectrometer), respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.04a
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• pp.85-88
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• 2006

The transport properties of amorphous selenium typical of the material used in direct conversion x-ray imaging devices are reported. The effects of As addition on the carrier mobility and recombination lifetime in amorphous selenium (a-Se) films have been studied using the moving photocarrier grating (MPG) technique. We have found an increase in hole drift mobility and recombination lifetime, especially when 0.3% As is added into a-Se film, whereas electron mobility decreases with As addition due to the defect density. The transport properties for As doped a-Se films obtained by using MPG technique have been compared with the drift mobilities of holes and electrons obtained by time of flight (TOF) measurement.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.3
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• pp.257-260
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• 2010

Advancements in the imaging and computing technology have opened the path to digital holography for non-destructive investigations of technical samples, material property measurement, vibration analysis, flow visualization and stress analysis in aerospace industry which has widened the application of digital holography in the above fields. In this paper, we demonstrate the non-destructive investigation and micro-structure measurement application of digital holography to the small particles and a biological sample. This paper gives a brief description of the digital holograms recorded with this system and illustratively demonstrated.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.2
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• pp.143-146
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• 2004

A surface plasmon resonance (SPR) imaging system was constructed and used to detect the hexahistidine-ubiquitin-tagged human parathyroid hormone fragment (His$\sub$6/-Ub-hPTHF(1-34)) expressed in Escherichia coli. The hexahistidine-specific antibody was immobilized on a thin gold film coated with ProLinker$\^$TM/ B, a novel calixcrown derivative with a bifunctional coupling property that permits efficient immobilizaton of capture proteins on solid matrices. The soluble and insoluble fractions of an E. coli cell lysate were spotted onto the antibody-coated gold chip, which was then washed with buffer (pH 7.4) solution and dried. SPR imaging measurements were carried out to detect the expressed His$\sub$6/-Ub-hPTHF(1-34). There was no discernible protein image in the uninduced cell lysate, indicating that non-specific binding of contaminant proteins did not occur on the gold chip surface. It is expected that the approach used here to detect affinity-tagged recombinant proteins using an SPR imaging technique could be used as a powerful tool for the analyses of a number of proteins in a high-throughput mode.