• The Journal of Korean Society for Radiation Therapy
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• v.27 no.1
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• pp.87-95
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• 2015

Purpose : This study presents the usefulness assessment of secondary shield for the lens exposure dose reduction during radiation treatment of peripheral orbit. Materials and Methods : We accomplished IMRT treatment plan similar with a real one through the computed treatment planning system after CT simulation using human phantom. For the secondary shield, we used Pb plate (thickness 3mm, diameter 25mm) and 3 mm tungsten eye-shield block. And we compared lens dose using OSLD between on TPS and on simulation. Also, we irradiated 200 MU(6 MV, SPD(Source to Phantom Distance)=100 cm, $F{\cdot}S\;5{\times}5cm$) on a 5cm acrylic phantom using the secondary shielding material of same condition, 3mm Pb and tungsten eye-shield block. And we carried out the same experiment using 8cm Pb block to limit effect of leakage & transmitted radiation out of irradiation field. We attached OSLD with a 1cm away from the field at the side of phantom and applied a 3mm bolus equivalent to the thickness of eyelid. Results : Using human phantom, the Lens dose on IMRT treatment plan is 315.9cGy and the real measurement value is 216.7cGy. And after secondary shield using 3mm Pb plate and tungsten eye-shield block, each lens dose is 234.3, 224.1 cGy. The result of a experiment using acrylic phantom, each value is 5.24, 5.42 and 5.39 cGy in case of no block, 3mm Pb plate and tungsten eye-shield block. Applying O.S.B out of the field, each value is 1.79, 2.00 and 2.02 cGy in case of no block, 3mm Pb plate and tungsten eye-shield block. Conclusion : When secondary shielding material is used to protect critical organ while irradiating photon, high atomic number material (like metal) that is near by critical organ can be cause of dose increase according to treatment region and beam direction because head leakage and collimator & MLC transmitted radiation are exist even if it's out of the field. The attempt of secondary shield for the decrease of exposure dose was meaningful, but untested attempt can have a reverse effect. So, a preliminary inspection through Q.A must be necessary.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.2
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• pp.315-333
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• 1990

This study was performed to measure the skin absorbed doses from full mouth standard intraoral radiography (l4 exposures) in bisecting angle and paralleling techniques. Thermoluminescent dosimeters were used in a phantom. Circular tube collimator(60㎜ in diameter, 20㎝ in length) and rectangular collimator(35㎜ × 44㎜, 40㎝ in length) were set for bisecting angle and paralleling techniques respectively. All measurement sites were classified into 8 groups according to distance from each point of central rays. The results were as follows: 1. The skin absorbed doses from the paralleling technique were significantly decreased than those from the bisecting technique in both points at central ray and points away from central ray. The percentage rates of decrease were greater at points away from central ray than those at central ray. 2. The skin absorbed doses at the lens of eye, parotid gland, submandibular gland and thyroid region were significantly decreased in paralleling techniuqe, but those of the midline of palate remained similar in both techniques. 3. The highest doses were measured at the site 20mm above the point of central ray for the mandibular premolars in bisecting angle technique and at the point of central ray for the mandibular premolars in paralleling techniques. The lowest doses were measured at the thyroid region in both techniques.

• Korean Journal of Optics and Photonics
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• v.24 no.1
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• pp.23-28
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• 2013

In this paper, an optical system was designed for 3D imaging laser radar with optical scanner. In order to make it easy to scan, the system was designed to inscribe the transmitting objective lens in the receiving lens. In transmitting optics, the beam expander was designed to have a zoom mechanism so that the transmitted beam size would be 4.8 m or 6.8 m at 1 km distance, when the laser source's numerical aperture value is between 0.13 and 0.22. The beam diameter at the target 1 km away was confirmed by design program. The receiving optics for the returning beam from the target was designed for the $16{\times}16$ array detector with $100{\mu}m$ pixel width. The spot diameter in every pixel was designed and verified to be less than $55{\mu}m$. The receiving optics' obscuration ratio by transmitting optics was 11%.

• Journal of Korean Ophthalmic Optics Society
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• v.1 no.1
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• pp.73-84
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• 1996

Satisfactory for children's spectacles fitting can only be achieved with the resonable selection and assortment of frames of different pad shapes, size, materials, the general property of sample frame are flexibility for the temple. Loughness for bridge and variety for the length of temple, a selection of the lens is chosen usually by the characteristic of the power, safty, size and so on, it will be comport fit of frame controlled the hight and width of pad and angle of pad between the nose side, frontal angle of pad will be determinded that whether a frame may be capable of providing a comport fit. An important part of the fitting of spectacles is the final adjustment before the wearer takes them away, and also their continued adjustment to maintain the optimum comport and lens efficiency. It is suggested that spectacle adjustment is essentially a practical art that can only be acquired by continual practice.

• Acta Via Serica
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• v.3 no.2
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• pp.73-90
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• 2018

The Silk Road tied the globe together for the first time by producing an early globalization phenomenon. Some consider that the ancient Silk Road disintegrated around the $18^{th}$ century CE due to the fall of the Muslim empires and the kingdoms between Asia and Europe. However, the maritime trade among East Asia and the Spanish dominion on the American continent reactivated the ancient Silk Road on some levels, and maintained trade dynamics until the $19^{th}$ century. This was possible because of Mexican silver and trade spots. Notwithstanding its historical background, Mexico seems so far away from the new Silk Road, or the Belt and Road Initiative in the $21^{st}$ century. Thus, this paper analyzes Mexico's historic and current role concerning the Silk Road. First, I conceptualize and compare the ancient Silk Road and Belt and Road Initiative through the lens of complex interdependence theory. I propose that, unlike the ancient Silk Road, the Belt and Road Initiative is a case of an induced complex interdependence. Second, I study the Manila Galleons' dynamics in order to trace the ancient ties with the Silk Road. I emphasize Mexican silver's contribution to East Asian economies and the importance of Mexico's role in the East Asia-Spanish trade. Consequently, I analyze Mexico's position in the Belt and Road Initiative. Finally, I present some concluding remarks about Mexico's role in the Silk Road.

• Journal of English Language & Literature
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• v.64 no.1
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• pp.61-76
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• 2018

This essay examines Toni Morrison's African-American characters' struggle in The Bluest Eye (1970) and Home (2012) through the lens of heteronormativity, arguing that they suffer double victimization due to both their race and gender. The Bluest Eye portrays a family tragedy caused by an African-American husband and wife's failure to live up to images of gender as represented in white, middle-class media. Written forty-two years later, Home describes an African-American man and woman who establish their own lives away from gendered standards after striving to meet social expectations and becoming traumatized in the process. Their adversities stem not only from the deeply rooted racial discrimination in American society but also from subtle gendered norms implanted by heteronormativity. Morrison's characters in her earlier narrative face a tragic denouement, ultimately destroying their children's lives. By contrast, Morrison's later characters explore more utopian ways of life unfettered by heteronormativity, overcoming hardships imposed by white-centered heteronormal society. By portraying socially victimized characters, Toni Morrison problematizes the power behind the discriminatory nature of heteronormativity and suggests a more gender-neutral, egalitarian way of organizing society, free from the constraints of heterosexuality and from violence created by normalized gender rules.

• Korean Journal of Optics and Photonics
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• v.32 no.1
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• pp.22-28
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• 2021

We try to extract three-dimensional information, such as the distance from a camera and the actual width and height of an object, from still photographs by a multilens smartphone camera, by means of parallax error. To obtain this information, we develop several formulas and design a method for experimental instrumentation. If the results from this paper were included in algorithms of multilens smartphone cameras, there would be various kinds of applications, such as in the workplace of architectural and civil engineering to obtain an actual dimension, or on a golf course to measure how far away a pin flag is. We expect many more applications of this study, because the multilens smartphone camera is already an important necessity of life.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.2 s.308
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• pp.19-29
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• 2006

As the security of personal information is becoming more important in mobile phones, we are starting to apply iris recognition technology to these devices. In conventional iris recognition, magnified iris images are required. For that, it has been necessary to use large magnified zoom & focus lens camera to capture images, but due to the requirement about low size and cost of mobile phones, the zoom & focus lens are difficult to be used. However, with rapid developments and multimedia convergence trends in mobile phones, more and more companies have built mega-pixel cameras into their mobile phones. These devices make it possible to capture a magnified iris image without zoom & focus lens. Although facial images are captured far away from the user using a mega-pixel camera, the captured iris region possesses sufficient pixel information for iris recognition. However, in this case, the eye region should be detected for accurate iris recognition in facial images. So, we propose a new fast iris detection method, which is appropriate for mobile phones based on corneal specular reflection. To detect specular reflection robustly, we propose the theoretical background of estimating the size and brightness of specular reflection based on eye, camera and illuminator models. In addition, we use the successive On/Off scheme of the illuminator to detect the optical/motion blurring and sunlight effect on input image. Experimental results show that total processing time(detecting iris region) is on average 65ms on a Samsung SCH-S2300 (with 150MHz ARM 9 CPU) mobile phone. The rate of correct iris detection is 99% (about indoor images) and 98.5% (about outdoor images).

• Korean Journal of Environment and Ecology
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• v.32 no.3
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• pp.256-260
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• 2018

Cannibalism is a widely observed phenomenon in the animal kingdom. However, it is rarely found among birds outside nests in the wild because it occurs irregularly and it is almost impossible to monitor animal behavior constantly. On 17 January 2017, this behavior was directly observed from a group of vultures feeding on a conspecific in a paddy field near Lake Geumho in Haenam-gun ($34^{\circ}35^{\prime}58.25^{{\prime}{\prime}}N$, $126^{\circ}26^{\prime}57.64^{{\prime}{\prime}}E$). It was observed and recorded with the binoculars and a camera with a telephoto lens in a car approximately 20 m (or 60 m) away from the site. The observer approached the feeding site after the last vulture had finished feeding and flown away and found remains of a vulture, including body feathers, skull, sterna keel, and both legs. It was the first report of cannibalism in Cinereous vulture Aegypius monachus in its overwintering grounds. The remaining skeleton was very fleshy, and the surrounding grass was wet with the blood of vulture. No other traces of a mammal or bird that could have been the vultures' prey were found. This report provides a detailed account of the events related to this rare observation and the causes that might have led to it.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.4 s.316
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• pp.67-73
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• 2007

An optical pick up generally has coupled dynamics between focusing and tracking servos. The coupled dynamics reduces tracking performance of optical disk drives. A conventional control method is holding the previous tracking control command in the presence of surface defect. The method has a long settling time. If the defective area is getting larger, objective lens will get away from the following track. In order to overcome this problem, this paper proposed a new control method for optical disk drives based on a prediction of tracking error and focusing error. We present how to compensate the coupled dynamics so that reduced setting time is achieved. It is verified by experiments that the proposed method brings an improved performance in the presence of surface defect as well as in the normal operating condition.