• Journal of the Korean Society for Precision Engineering
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• v.25 no.2
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• pp.43-48
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• 2008

This paper proposes a new method for measuring the power of spherical and cylindrical lens with 6 points light source, which is composed of a LED and six holes, and magnification ellipse fitting algorithm. Each measured diagonal length of 6 points light source is determined by the target lens power. After finding the center position of each light point with threshold method, 3 axis-diagonal lengths were calculated. The long axis and short axis power of cylindrical lens can be calculated by using magnification ellipse fitting algorithm with the magnification relationships between the initial diagonal lengths and the measured diagonal lengths changed by lens power.

• Journal of radiological science and technology
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• v.45 no.4
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• pp.313-320
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• 2022

Both angiography and interventional procedures accompanied by angiography provide many diagnostic and therapeutic benefits to patients and are rapidly increasing. However, unlike general radiography or computed tomography using the same X-ray, the amount of radiation is quite high, but the dose range can vary considerably for each patient and operator. The high sensitivity of the lens to radiation during cerebral angiography and neurointervention is already well known, and although there are many related studies, it is insufficient to easily reduce radiation in diagnosis and treatment. In this situation, in particular, by adding three-dimensional rotational angiography (3D-RA) to the existing two-dimensional (2D) angiography, it is now possible to make an accurate diagnosis. However, since this 3D-RA acquires images through projection of more radiation than before, the exposure dose of the lens may be higher. Therefore, we tried to analyze whether the radiation dose of the lens can be reduced by moving the lens out of the field range by adjusting the table height and magnification ratio during the examination using 3D-RA. The surface dose was measured using a rando phantom and a radiophotoluminescent glass dosimeter (PLD) and the radiation dose was compared by adjusting the table height and magnification ratio based on the central point. As a result, it was found that the radiation dose of the lens decreased as the table height increased from the central point, that is, as the lens was out of the field of view. In conclusion, in 3D-RA, moving the table position of about 2 cm in height will make a significant contribution to the dose reduction of the lens, and it was confirmed that adjusting the magnification ratio can also reduce the surface dose of the lens.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.1
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• pp.199-203
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• 2000

Magnification shall large to test a surface of a contact lens also chromatic aberration and distortion to be removed. Be used of this study a contact lens analyzer is "CONTACT LENS ANALYZER CA-20", it is a good analyzer to suitable with surface test 16 times of big magnification and distortion.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.655-658
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• 2009

Fractal dimension has been used for texture analysis as it is highly correlated with human perception of surface roughness and applied to quantifying the structures of wide range of objects in biology and medicine. On the other hand, the evaluation of the human skin state is based solely on the subjective assessment of clinicians; this assessment may vary from moment to moment and from rater to rater. Therefore we attempt to analysis of skin texture image using fractal dimension and discuss its application to evaluating human skin state. It can be helpful for extracting human features and also can be useful for detection of many human skin diseases. This paper presents a method to calculate fractal dimension of skin with use of camera lens magnification. We take multiple pictures frequently from skin with different camera lens magnification as a magnification factor of fractal set, and counting the number of objects (cells) in each picture as a number of self similar pieces of fractal set.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.5
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• pp.60-65
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• 1997

This paper proposes a profilometry system for precise surface contouring of 3D objects using a direc- tionally magnified image of a laser light stripe. The resolution of this system can be improved several times comparad with that of conventional systems without loss of spatial resolution and depth of measurement. A pair of cylindrical lens(a convex lens and a concave lens) are used for a directionally magnified image of a laser light stripe maintaining the same focal plane. Also, image processing procedures for image reconstruc- tions are described.

• Korean Journal of Optics and Photonics
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• v.34 no.2
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• pp.66-71
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• 2023

Zoom lenses are now starting to be applied to mobile-phone cameras as well. A zoom lens applied to a mobile-phone camera is mainly used to capture images in the telephoto range. Such an optical system has a long focal length, similar to that of a high-magnification zoom optical system, so the position of the imaging device also shifts significantly, due to manufacturing errors of the lenses and mechanical parts. In the past, the positional shift of the imaging device was corrected by moving the first lens group and the total optical system, but this paper confirms that the position of the imaging device can be corrected by selecting any two moving lens groups. However, it is found that more distance must be secured in the front and rear of a moving lens group for this purpose.

• Journal of the Optical Society of Korea
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• v.17 no.2
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• pp.136-141
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• 2013

A method to determine the transverse magnification (TM) of an imaging system is discussed. This method is different in that TM can be determined accurately by using distortion analysis. We demonstrate the validity of the method via numerical simulation with accompanying experimental data for a thick bi-convex lens.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.629-634
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• 2000

This System is developed for the estimation of the Camera Lens Resolution. Signal data proportional to light intensity is obtained and sampled from the 2D CCD. Based on the measured signal. the MTF charateristcs of a camera lens are measured. We could measure the sagittal and tangential MTF in the on and off-axis at the same time. The automatic measurig methods for optimal image plane, magnification, and best marginal direction of test lens are presented.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.3
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• pp.29-35
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• 2009

Purpose: To develop a relay lens type scope with 70 mm eye relief. Methods: By using Sigma 2000 design program, we designed and manufactured a relay lens type scope with 70 mm eye relief, which is integrated after designing an objective part with relay lenses and an eyepiece part, respectively. Results: The characteristics of the relay lens type scope with 70 mm eye relief whch is designed and manufactured by methods, which integrate after respectively designing an object part with relay lenses and an eyepiece part, have the magnification of $+4{\times}$,the length from 1st lens to last lens of about 105 mm, the barrel diameter of 18mm, and the effective diameter of 13 mm. Also we know that the resolution line width is 275 cycles/rad at the 30% MTF value criterion. Conclusions: We could design and manufacture the relay type scope with 70 mm eye relief, the characteristics of which have the magnification of $+4.0{\times}$the MTF above 30% at 275 cycles/rad, and the length from 1st lens to last lens of about 105 mm.

• Applied Microscopy
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• v.35 no.4
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• pp.98-104
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• 2005

A FOV (field-of-view) of the HV-MSC (high voltage multi-scan CCD, $1024{\times}1024$ pixels) camera mounted in the post-column HV-GIF (high voltage gatan image filter) has been drastically enlarged by the projection lens current adjustment. An imaging area of the HV-MSC camera obtained at the lowest magnification (2,000x) is $112{\mu}m^2$ which corresponds to the recording area of the film at the magnification of 8,800x, while the achievable recording area is only $0.43{\mu}m^2$ at the same magnification without this technique. Ignoring the image distortion of less than 5%, we have designed an on-site reference graph to estimate projection lens currents for microscope magnifications above 8,800x, where the recording area on the HVMSC is same as that on the film.