• Journal of electromagnetic engineering and science
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• v.2 no.1
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• pp.39-44
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• 2002

A high speed data link capability is one of the critical factors in determining the performance of the spaceborne SAR system with high resolution because of the strict requirement far the real-time data transmission of the massive SAR data in a limited time of mission. In this paper, based on the data lint model characterized by the spaceborne small SAR system, the high rate multi-channel data link module is designed including link storage, link processor, transmitter, and wide-angle antenna. The design results are presented with the performance analysis on the data link budget as well as the multi-mode data rate in association with the SAR imaging mode of operation from high resolution to the wide swath.

• Proceedings of the KIEE Conference
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• 1979.08a
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• pp.160-161
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• 1979

The degradation of image due to the finite size of sensing device has been one of the problems to all of the digital imaging systems. The improvement of the spatial resolution has been attempted by "differential method" with fixed sensor size and finer sampling. The computer simulations were carried out for the cases of PLF system (Parallel Linear Fan-beam) and SR(Stationary Ring) system and the results are presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.31-36
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• 2004

Optical coherence tomography system has been extensively studied because it has some advantages such as imaging of high resolution, low cost, and compact size configuration. In order to obtain high resolution of OCT system we configured OCT system using a femto-second laser. We measure the pulse width using autocorrelator function because a femto-second laser is ultra short pulse. And we measured the practical resolution using theoretical equation and the measurement of reference sample. It is confirmed that the proposed OCT system has 1.5 times higher resolution and un distinctive cross-sectional image than OCT system with SLD as a light source.

• Journal of Radiation Protection and Research
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• v.34 no.1
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• pp.25-30
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• 2009

Micro-columnar CsI(Tl) is the most popular scintillator material which is used for many indirect digital X-ray imaging detectors. The light scattering at the surface of micro-columnar CsI(Tl) scintillator was studied to find the correlation between the surface roughness and the resultant image resolution of indirect X-ray imaging detectors. Using a commercially available optical simulation program, Light Tools, MTF (Modulation Transfer Function) curves of the CsI(Tl) film thermally evaporated on glass substrate with different thickness were calculated and compared with the experimental estimation of MTF values by the edge X-ray image method and CCD camera. It was found that the standard deviation value of Gaussian scattering model which is determined by the surface roughness of micro-columns could certainly change the MTF value of image sensors. This model and calculation methodology will be beneficial to estimate the overall performance of indirect X-ray imaging system with CsI(Tl) scintillator film for optimum design depending on its application.

• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3844-3853
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• 2023

Although radiation and chemotherapy methods for cancer therapy have advanced significantly, surgical resection is still recommended for most cancers. Therefore, intraoperative imaging studies have emerged as a surgical tool for identifying tumor margins. Intraoperative imaging has been examined using conventional imaging devices, such as optical near-infrared probes, gamma probes, and ultrasound devices. However, each modality has its limitations, such as depth penetration and spatial resolution. To overcome these limitations, hybrid imaging modalities and tracer studies are being developed. In a previous study, a multi-modal laparoscope with silicon photo-multiplier (SiPM)-based gamma detection acquired a 1 s interval gamma image. However, improvements in the near-infrared fluorophore (NIRF) signal intensity and gamma image central defects are needed to further evaluate the usefulness of multi-modal systems. In this study, an attempt was made to change the NIRF image acquisition method and the SiPM-based gamma detector to improve the source detection ability and reduce the image acquisition time. The performance of the multi-modal system using a complementary metal oxide semiconductor and modified SiPM gamma detector was evaluated in a phantom test. In future studies, a multi-modal system will be further optimized for pilot preclinical studies.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.53-56
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• 2004

Recently the interferometric synthetic aperture radiometer with sub-Y-type antenna array was suggested to improve the spatial resolution than that of conventional Y-type with the same number of antenna elements. The sub-Y-type performance has been reported under a point source target. In this paper, the performance of sub-Y-type is evaluated under contiguous objects. The angular resolution of sub-Y-type with 52 antennas was compared with that of Y-type with the 40 antennas. The images of sub-Y -type and Y-type array were simulated under the contiguous objects. The sub-Y-type showed higher resolution than Y-type in the simulation and experiments. The sub-Y-type has high spatial resolution than Y-type in case of contiguous source as well as single point source.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.209-216
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• 2018

High-resolution satellite imagery is used in diverse fields such as meteorological observation, topography observation, remote sensing (RS), military facility monitoring and protection of cultural heritage. In satellite imagery, low-resolution imagery can take place depending on the conditions of hardware (e.g., optical system, satellite operation altitude, image sensor, etc.) even though the images were obtained from the same satellite imaging system. Once a satellite is launched, the adjustment of the imaging system cannot be done to improve the resolution of the degraded images. Therefore, there should be a way to improve resolution, using the satellite imagery. In this study, a super resolution (SR) algorithm was adopted to improve resolution, using such low-resolution satellite imagery. The SR algorithm is an algorithm which enhances image resolution by matching multiple low-resolution images. In satellite imagery, however, it is difficult to get several images on the same region. To take care of this problem, this study performed the SR algorithm by calibrating geometric changes on images after applying automatic extraction of feature points and projection transform. As a result, a clear edge was found just like the SR results in which feature points were manually obtained.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.3
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• pp.283-288
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• 2013

This paper describes development of a high speed Doppler OFDI system for non-invasive vascular imaging. Doppler OFDI (optical frequency domain imaging) is one of the phase-resolved second generation OCT (optical coherence tomography) techniques for high resolution imaging of moving elements in biological tissues. To achieve a phase-resolved imaging, two temporally separated measurements are required. In a conventional Doppler OCT, a pair of massively oversampled successive A-lines is used to minimize de-correlation noise at the expense of significant imaging speed reduction. To minimize a de-correlation noise between targeted two measurements without suffering from significant imaging speed reduction, several methods have been developed such as an optimized scanning pattern and polarization multiplexed dual beam scanning. This research represent novel imaging technique using frequency multiplexed dual beam illumination to measure exactly same position with aimed time interval. Developed system has been verified using a tissue phantom and mouse vessel imaging.

• Imaging Science in Dentistry
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• v.49 no.2
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• pp.97-102
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• 2019

Purpose: This study was conducted to evaluate the effect of different spatial resolutions of a photostimulable phosphor plate (PSP) radiography system on the detection of proximal caries lesions. Materials and Methods: Forty-five extracted human permanent teeth were radiographed using a PSP system (VistaScan Perio Plus) and scanned at the 4 resolutions (10 lp/mm, 20 lp/mm, 25 lp/mm, and 40 lp/mm) available in the system. Three independent examiners scored the images for the presence and absence of proximal caries lesions using a 5-point scale. The presence or absence of caries was confirmed by histological sections of the examined teeth (defined as the gold standard). Intra- and inter-observer reproducibility was calculated by the weighted kappa test. One-way analysis of variance with the post hoc Tukey test was used to compare the area under the receiver operating characteristic curve for the classifications made with each resolution. Results: For the detection of enamel lesions, the spatial resolution of 10 lp/mm was significantly superior to the other resolutions. However, the spatial resolution did not affect the detection of caries lesions in dentin (P>0.05). Conclusion: Spatial resolution may influence the accuracy of the detection of incipient caries lesions in radiographs with PSP plates. Images with low spatial resolution seem to be more appropriate for this purpose.

• Proceedings of the KSMRM Conference
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• 2004.09a
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• pp.44-44
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• 2004