• Proceedings of the Korean Society of Veterinary Clinics Conference
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• 2009.10a
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• pp.266-266
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• 2009

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.6
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• pp.413-417
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• 2010

To understand the function of edges in perception of moving objects, we defined four questions to answer. Is the focus point in visual motion detection of a moving object: (1) the body or the edge of the object, (2) the leading edge or trailing edge of the object, (3) different in scotopic, mesopic and photopic luminance levels, or (4) different for colored objects? We measured the Optomotor Response (OMR) and Edge Triggering Response (ETR) of goldfish. We used a square and sine wave patterns with black and red stripes and a square wave pattern with black and grey stripes to generate OMR's and ETR's in the goldfish. When we used black and red stripes, the black leading edges stimulated an ETR under scotopic conditions, red leading edges stimulated an ETR under photopic conditions, and both black and red leading edges stimulated an ETR under mesopic luminance levels. For black and gray stripes, only black leading edges stimulated an ETR in all three light illumination levels. We observed less OMR and ETR results using the sine wave pattern compared to using the square wave pattern. From these results, we deduced that the goldfish tend to prefer tracking the leading edge of the pattern. The goldfish can also detect the color of the moving pattern under photopic luminance conditions. We decided that ETR is an intriguing factor in OMR, and is suitable as a method of behavioral measurement in visual system research.

• Journal of Information Display
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• v.11 no.2
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• pp.57-62
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• 2010

A method of characterizing time-sequential stereoscopic 3D displays based on the measurement of the temporal behavior of the systems vs. the grey levels is proposed. An Nvidia 3D vision kit with a 3D-ready SAMSUNG 2233RZ LCD display is characterized in the paper. OPTISCOPE SA especially designed for the precise measurements of the luminance and temporal behavior of LCD displays was used. The transmittance and response time of the shutter glasses was first evaluated. Then the grey-to-grey response times of the display were measured. The 2D and 3D behaviors of the display were then compared. Finally, the temporal behavior of the complete system was modeled, and the grey-level variations on one view were deduced as a function of the synchronization and level of the other eye. The main sources of imperfection were identified and quantified, and a full computation of the system performances was done.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.205-211
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• 1998

The MTF(modulation transfer function) measuring system with a linear CCD(charge coupled-device) was constructed to cvaluate a color CRT(catode ray tube). The measured MTF values were corrected by considering the spectral response and the pixel sizes of CCD. The effects of a spot size, video bandwidth, pitch of shadow mask holes, display luminance, and ambient illumination on image quality were studied. The uniformity of resolution and the contrast Ioss by ambient light of the color CRT monitor were measured, and the results were analyzed by MTFA(modulation threshold area).

• Korean Journal of Digital Imaging in Medicine
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• v.10 no.1
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• pp.21-28
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• 2008

Diagnostic display monitor QA according to AAPM TG18 is usually performed by PACS administrator, product manager and reading doctor, and for acceptance testing and periodic quality control evaluation, a combination of visual and quantitative tests can be used, as outlined in sections 5 and 6 of 'assessment of display performance for medical imaging systems'. Although many display tests can be performed visually, a more objective and quantitative evaluation of display performance requires special test tools. The required instruments vary in their complexity and cost, depending on the context of the evaluation(research, acceptance testing, or quality control) and how thorough the evaluation needs to be. Objective and reliable assessment of many display characteristics can be performed with relatively inexpensive equipment, So, we made 'AAPM TG18 guiding instrument' to ues variable purpose of the evaluation of 'geometrical distortions(quantitative"', 'veiling glare(visual)' and 'sensor calibration'. The spatial measurements for the quantitative evaluation of geometric distortions, and the measurement of the veling-glare ring response function which provides information regarding the spatial extent of the luminance spread, can be performed using the TG18 guiding instrument can be used to sensor calibration to standardize the basic rate of 0% luminance when periodic calibration.

• Korean Journal of Remote Sensing
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• v.24 no.2
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• pp.99-106
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• 2008

A synthetic aperture radar (SAR) system is of great interest in many fields of civil and military applications because of all-weather and luminance free imaging capability. SAR image quality parameters such as spatial resolution, peak to sidelobe ratio (PSLR), and integrated sidelobe ratio (ISLR) can be normally estimated by modeling of impulse response function (IRF) which is obtained from various system design parameters such as altitude, operational frequency, PRF, etc. In modeling of IRF, however, background clutter environment surrounding the IRF is generally neglected. In this paper, analysis method for SAR mage quality is proposed in the real background clutter environment. First of all, SAR raw data of a point scatterer is generated based on various system parameters. Secondly, the generated raw data can be focused to ideal IRF by range Doppler algorithm (RDA). Finally, background clutter obtained from image of currently operating SAR system is applied to IRF. In addition, image quality is precisely analyzed by zooming and interpolation method for effective extraction of IRF, and then the effect of proposed methodology is presented with several simulation results under the assumption of estimation error of Doppler rate.

• Progress in Medical Physics
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• v.25 no.1
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• pp.31-36
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• 2014

We aimed to evaluate the dosimetric characteristics of reproducibility, linearity and dose dependence of optical stimulated luminance dosimeter (OSLD) in the Co-60 Gamma-rays and to analyze with a precedent study in field of the diagnostic radiography and radiotherapy. The reproducibility was 0.76% of the coefficient of variation, the homogeneity was within 1.5% of the coefficient of variation and OSLD had supra-linear response more than 3 Gy. So the correlation between dose and count was fitted by quadratic function. The count depletion by repeated reading was 0.04% per reading regardless of the irradiated dose. And the half time of decay curve according to the irradiated dose was 0.68 min. with 1 Gy, 1.04 min. with 5 Gy, and 1.10 min. with 10 Gy, respectively. In case of annealing for 30 min, the removal rate was 88% with 1 Gy, 90% with 5 Gy, and 92% with 10 Gy, respectively and 99% in case of annealing time for 4 hour. It is feasible to use OSLDs for dose evaluation in Co-60 Gamma-rays when considering the uncertainty on the procedure according to the irradiated dose.