• Journal of Applied Reliability
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• v.10 no.2
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• pp.137-148
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• 2010

This study deals with the accelerated life test of high power phosphor converted white Light Emitting Diodes (High power LEDs). Samples were aged at $110^{\circ}C$/85% RH and $130^{\circ}C$/85% RH up to 900 hours under non-biased condition. The stress induced a luminous flux decay on LEDs in all the conditions. Aged devices exhibited modification of package silicon color from white to yellowish brown. The instability of the package contributes to the overall degradation of optical lens and structural degradations such as generating bubbles. The degradation mechanisms of lumen decay and reduction of spectrum intensity were ascribed to hygro-mechanical stress which results in package instabilities.

• Korean Journal of Optics and Photonics
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• v.12 no.6
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• pp.512-518
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• 2001

In this paper, the geometrical properties of the optical system for Head Mounted Display (HMD) were investigated. Also, this work deals with the concept for an optical system design bated on Diffractive Optical Elements (DOE). In designing the optical system for HMD, it is considered that the optical system should have compact, high performance, and comfortable properties while user sees the picture. In order to satisfy these requirements, we applied DOE and aspheric surfaces to the lens so that correction of color and monochromatic aberrations could be obtained. Also, the design and evaluation for the optical system were carried out using the generalized model of the human eye. Finally, it was expected to fulfill all the requirements of an HMD system.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.106-110
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• 2002

4S-Van is being developed in order to provide the spatial data rapidly and accurately. 4S-Van technique is a system for spatial data construction that is heart of 4S technique. Architecture of 4S-Van system consists of hardware integration part and post-processing part. Hardware part has GPS, INS, color CCD, camera, B/W CCD camera, infrared rays camera, and laser. Software part has GPS/INS integration algorithm, coordinate conversion, lens correction, camera orientation correction, and three dimension position production. In this paper, we suggest that adequate 4S-Van design is needed according to application environment from various test results.

• Journal of the Optical Society of Korea
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• v.5 no.2
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• pp.43-48
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• 2001

A three-dimensional (3D) display system based on computer-generated integral photography (CGIP) is proposed and its feasibility is discussed. Instead of the pickup process in conventional If, the elemental images of imaginary objects are computer-generated. Using these images, we observed autostereoscopic 3D images in full color and full parallax. The lateral and depth resolutions of the integrated images are limited by some factors such as the image position, object thickness, the lens width, and the pixel size of display panel.

• Journal of the Optical Society of Korea
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• v.5 no.3
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• pp.117-122
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• 2001

A three-dimensional (3D) display system based on computer-generated integral photography (CGIP) is proposed and its feasibility is discussed. Instead of the pickup process in conventional IP, the elemental images of imaginary objects are computer-generated. Using these images, we observed autostereoscopic 3D images in full color and full parallax. The lateral and depth resolutions of the integrated images are limited by some factors such as the image position, object thickness, the lens width, and the pixel size of display panel.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.12
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• pp.1816-1822
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• 2016

This study investigated the quality characteristics and antioxidant activities of madeleine added with lentil powder (LP). Madeleine was prepared with flour levels of lentil powder (0, 20, 40, and 60%). The pH, moisture, and specific gravity of madeleine decreased with increasing amounts of LP, whereas loss rate increased. Hunter L and b values of crust decreased with increasing amounts of LP, whereas a value of crust increased (P<0.05). Hunter L and b values of crumb increased with increasing amounts of LP, whereas a value of crumb decreased (P<0.05). For texture of madeleine with increasing amounts of LP, hardness and adhesiveness increased, whereas springiness, cohesiveness, and chewiness were reduced. DPPH radical scavenging activity of LP madeleine significantly increased with increasing amounts of LP (P<0.05). In the sensory evaluation of appearance, color, flavor, texture, taste, and overall preference, madeleine with LP 20% showed the highest value. It is suggested that LP 20% madeleine could be substituted for wheat flour to improve madeleine quality.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.2
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• pp.81-89
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• 2006

The purpose of this study was to evaluate the applicability of small RC(radio controlled) helicopter and single lens reflect camera as SFAP(Small Format Aerial Photography) aquisition system to monitor the vegetation coverage of wetland. The system used to take pictures of small artificial wetland were a common optical camera(Nikon F80 with manual lens whose focal length was 28mm) attached to the bottom of a RC helicopter with a 50 cubic inch size glow engine. Three hundreds pictures were taken at the altitude of 50m above the ground, from 23rd June to 7th September 2005. Four from the images were selected and scanned to digital images whose dimension were 2048${\times}$1357 pixels. Those images were processed and rectified with GCP(Ground Control Poins) and digital map, and then classified by the supervised- classification module of image processing program PG-steamer Version 2.2. The major findings were as follows ; 1. The final images processed had very high spatial resolution so that the objects bigger than 30mm like lotus(Nelumbo nucifera), rock and deck were easily identified. 2. The dominant plants of the monitoring site were Monochoria ragianlis, Typha latifolia, Beckmannia syzigachne etc. Because those species have narrow and long leaves and form irregular biomass, the individuals were hardly identifiable, but the distribution of population were easily identifiable depending on the color difference. 3. The area covered by vegetation was rapidly increased during the first month of monitoring. At the beginning of the monitoring 23th June 2005, The rate of area covered by vegetation were only 34%, but after 27 and 60 days it increased to 74%, and the 86% respectively.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.1
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• pp.19-27
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• 2004

The purpose of this study is to survey spectacle wearers's way of thinking through the questionaire and to investigate their wearing conditions through fitting conditions, the pantascopic angle, vertex distance, the coincidence of vertical and horizontal distance between optical center of the lens and pupillary distance of the eye in random selected 150 ametropic corrective wearers in the age of 17 to 19. The results are as follows : 1. The most popular causes of physical complaints in the ex-wearing spectacle are frame pressure(34.0%), slipping forward(30.0%) and most popular visual complaints are blur vision(30.0%) and asthenopia(20.0%). 2. The most common physical or visual complaints in the present wearing spectacle are slipping forward(30.0%), pressure (50.0%), color(10.0%). 3. Myopic glasses wearers accounted for 56.7% of the subjects, the others were compound myopic astigmatism. In 60% of the subjects' binocular diopter did not coincide. 4. In the pantascopic angle of the both eyes coincide in 66.7% of the subjects. The average of pantascopic angle is $10.07^{\circ}$. 5. In the vertex distance of the both eyes coincided in 65.3% of the subjects. the he average of vertex distance is 13.6 mm. 6. Among 150 eyes with monocular, the vertical distance between optical center of the lens and pupillary distance of the eye is within the RAL-RG 915 that is tolerance of ophthalmic dispensing in German Standards in 82 eyes (54.6%). 7. Among 150 eyes with monocular, the horizontal distance between optical center of the lens and pupillary distance of the eye is within the RAL-RG915 that is tolerance of ophthalmic dispensing in German Standards in 86 eyes(57.3 %).

• Journal of Broadcast Engineering
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• v.23 no.1
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• pp.146-153
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• 2018

This paper presents a superresolution demosaicing technique that can restore high-resolution color image from differently blurred low resolution images in Bayer domain. The proposed superresolution demosaicing algorithm uses an aperture mask wheel to get differently blurred low resolution images, so we just need to estimate point spread function at each frame. In addition, it does not require image registration because there is no translational motion between low resolution images. By using a rotatable aperture mask wheel, consecutive captured images provide sufficiently exclusive information for superresolution. Therefore, the proposed method can reduce the registration error between the low-resolution image as well as the calculation amount for superresolution restoration. The existing lens system of the camera can be extended to obtain a superresolution image by only adding an rotatable aperture mask wheels. Finally, in order to verify the performance of the proposed system, experimental results are performed. The proposed method showed the significant improvements in the sense of spatial and color resolution.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3427-3433
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• 2009

This paper attempted to suggest the standards of light transmittance based on the analysis of the changes in contrast sensitivity of photopic condition according to the light transmittance of tinted lenses. The subjects of the experiment were 24 male and 13 female adults with normal ocular functions. They were asked to wear four tinted lenses (gray, brown, red, and green) in turn. The light transmittance of the lenses were 80~90%, 60~80%, 43~60%, and 30~43%, respectively. Contrast sensitivities were measured by using F.A.C.T. chart. The results showed that contrast sensitivities were decreased in proportion to the decrease of the light transmittance, and visual sensitivity of brown lenses were the highest and that of red lenses were the lowest. The results of the experiments suggested that the light transmittance should be over 38% for brown, gray and green lenses, and over 52% for red lenses. Accordingly the appropriate light transmittance should be considered when tinted lenses are selected for the purpose of eye protection in everyday life.