• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.517-522
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• 2014

In this paper we propose an axially distributed image-sensing method with a wide-angle lens to capture the wide-area scene of 3D objects. A lot of parallax information can be collected by translating the wide-angle camera along the optical axis. The recorded wide-area elemental images are calibrated using compensation of radial distortion. With these images we generate volumetric slice images using a computational reconstruction algorithm based on ray back-projection. To show the feasibility of the proposed method, we performed optical experiments for visualization of a partially occluded 3D object.

• Journal of the Optical Society of Korea
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• v.17 no.5
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• pp.405-409
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• 2013

In this paper, a unifying framework to evaluate the depth resolution of axially distributed image sensing (ADS) systems under fixed resource constraints is proposed. The proposed framework enables one to evaluate the system performance as a function of system parameters such as the number of cameras, the number of pixels, pixel size, and so on. The Monte Carlo simulations are carried out to evaluate ADS system performance as a function of system parameters. To the best of our knowledge, this is the first report on quantitative analysis of ADS systems under fixed resource constraints.

• Journal of the Optical Society of Korea
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• v.16 no.3
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• pp.270-276
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• 2012

An off-axis integral floating system using a concave mirror is analyzed to resolve the image distortion incurred by the off-axis optical arrangement. The concave mirror can be adopted as the floating device to improve the optical efficiency. The image distortion due to the tilting axis of the concave mirror needs to be analyzed precisely to generate the pre-distortion image. In this paper, we calculate the image deformation in the off-axis structure of the concave mirror using the geometrical optics. Using the calculation results, the compensated elemental image can be generated for the pre-distortion integrated image, which can be projected to the floating 3D image without image distortion. The basic experiments of the off-axis integral floating are presented to prove and verify the proposal.

• Korean Journal of Optics and Photonics
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• v.24 no.5
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• pp.237-244
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• 2013

Supermultiview and electro-holographic displays are promising displays for the future because they provide continuous parallaxes as their depth cue. But they are still in the early development stage due to the lack of supporting technologies. Achieving the continuous parallax in the supermultiview relies more on the number and size of pixels in the pixel cell/elemental image rather than the number of different view images. For the electro-holographic display, it also relies on the number and size of pixels in the panel. So these two methods share the same requirements for achieving the parallax. But the image displayed on the holographic display provides more impressive visual appeal than that on the supermultiview because the image can be floated on the front space of the display.

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.301-308
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• 2024

Ceramic materials are being explored as alternatives to toxic lead sheets for radiation shielding due to their favorable properties like durability, thermal stability, and aesthetic appeal. However, crafting effective ceramics for radiation shielding entails complex processes, raising production costs. To investigate local viability, this study evaluated Malaysian ceramic tiles for shielding in diagnostic X-ray rooms. Different ceramics in terms of density and thickness were selected from local manufacturers. Energy Dispersive X-ray Fluorescence (EDXRF) and X-ray Fluorescence (XRF) characterized ceramic compositions, while Monte Carlo Particle and Heavy Ion Transport code System (MC PHITS) simulations determined Linear Attenuation Coefficient (LAC), Half-value Layer (HVL), Mass Attenuation Coefficient (MAC), and Mean Free Path (MFP) within the 40-150 kV energy range. Comparative analysis between MC PHITS simulations and real setups was conducted. The C3-S9 ceramic sample, known for homogeneous full-color structure, showcased superior shielding attributes, attributed to its high density and iron content. Notably, energy levels considerably impacted radiation penetration. Overall, C3-S9 demonstrated strong shielding performance, underlining Malaysia's potential ceramic tile resources for X-ray room radiation shielding.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.2
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• pp.411-418
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• 2018

This paper presents a novel three-dimensional (3D) object encryption scheme by combining the use of the virtual optics and the chaotic sequence. A virtual 3D object is digitally produced using a two-dimensional (2D) elemental image array (EIA) created with a virtual pinhole array. Then, through a logistic mapping of chaotic sequence, a final encrypted video can be produced. Such method converts the value of a pixel which is the basic information of an image. Therefore, it gives an improved encryption result compared to other existing methods. Through computational experiments, we were able to verify our method's feasibility and effectiveness.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.712-717
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• 2013

In this paper, we propose a performance-enhanced object recognition by using nonlinear 3D correlator based on pixel restoration. In the proposed method, elemental images of the 3D target that are partially occluded by a foreground object are picked up and transformed into sub-images. By using the block-matching algorithm, the occluded target regions of each sub-image are estimated and removed. After that, the missing pixels in each sub-image are reestablished by using the pixel-restoration method. Finally, through the nonlinear cross-correlations between the reconstructed reference and the target plane images, the improved object recognition can be performed. To show the feasibility of the proposed method, some preliminary experiments are carried out and results are presented by comparing the conventional method.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.6
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• pp.1-9
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• 2010

In this paper, we propose an efficient compression method of the integral images. The integral imaging is a well-known technique to represent and record three-dimensional images. The proposed method is based on three dimensional discrete cosine transform (3D-DCT). The 3D-DCT techniques for the integral images have been reported as an efficient coding method for the integral images which reduces the redundancies between adjacent elemental images. The proposed method is a compression method efficient to integral images using adaptive block mode(ABM), based on the 3D-DCT technique. In the ABM, 3D-DCT blocks adaptive to the characteristics of integral images are constructed, which produces variable block size 3D-DCT blocks, and then 3D-DCTs for the 3D blocks are performed. Experimental results show that the proposed method gives significant improvement in coding efficiency. Especially, at the high bit-rates, the proposed method is more excellent since the overhead incurred by the proposed method take less part of the total bits.

• Environmental Engineering Research
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• v.25 no.4
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• pp.579-587
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• 2020

Novel silane grafted bentonite was obtained using the natural bentonite as precursor material. The material which is termed as nanocomposite was characterized by the Fourier Transform Infra-red (FT-IR) and X-ray diffraction (XRD) methods. The surface imaging and elemental mapping was performed using Scanning Electron Microscopic (SEM/EDX) technique. The electroanalytical studies were performed using the nanocomposite electrode. The electroactive surface area of nanocomposite electrode was significantly increased than the pristine bentonite or bare carbon paste based working electrode. The impedance spectroscopic studies were conducted to simulate the equivalent circuit and Nyquist plots were drawn for the carbon paste electrode and nanocomposite electrodes. A single step oxidation/reduction process occurred for As(III) having ΔE value 0.36 V at pH 2.0. The anodic stripping voltammetry was performed for concentration dependence studies of As(III) (0.5 to 20.0 ㎍/L) and reasonably a good linear relationship was obtained. The detection limit of the As(III) detection was calculated as 0.00360±0.00002 ㎍/L having with observed relative standard deviations (RSD) less than 4%. The presence of several cations and anions has not affected the detection of As(III) however, the presence of Cu(II) and Mn(II) affected the detection of As(III). The selectivity of As(III) was achieved using the Tlawng river water sample spiked with As(III).

• The Korean Journal of Nuclear Medicine
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• v.30 no.1
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• pp.1-14
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• 1996

Since the publication of the first bone scintiscans in 1962 three decades have elapsed. The bone scan has made great strides during this period, becoming one of the most commonly used nuclear imaging tests. In spite of the progress, however, the specificity of bone scan has remained relatively low. As the result it is a common practice to seek additional information from radiograph, CT scan and MR image, which is euphemistically termed as "image fusion or co-location." The basic reason is the inapplicability of the classical piecemeal analysis to interpreting planar and SPECT bone scans. Such analysis has its base on the observation of elemental features of morphology, which include the size, shape, contour, location, topography and internal architecture. The physiochemical profile may well also be included. Understandably, however, the miniatured images of the planar bone scan cannot provide these features in acceptable detail and the same holds true even with SPECT Images which are but sliced views of the reconstructed planar scans. Fortunately pinhole scanning has the capacity to portray both the morphological and chemical profiles of bone and joint diseases in greater detail through true magnification. The magnitude of pinhole scan resolution is practically comparable to that of radiography as far as gross anatomy is concerned. Thus, we feel strongly that pinhole scanning is a potential breakthrough of the long-lamented low specificity of bone scan. This presentation will discuss the fun-damentals, advantages and disadvantages and the most recent advances of pinhole scanning. It high-lights the actual clinical applications of pinhole scanning in relation to the diagnosis of infective and inflammatory diseases of bone and joint.