• Journal of Electrical Engineering and Technology
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• v.10 no.6
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• pp.2334-2342
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• 2015

This paper proposes an LED driving circuit with a digital controller, power factor correct (PFC) function, and low light flicker. The key topology of the proposed circuit is a conventional Flyback combined with a pre-stage. As a result, there will be less light flicker than with other one-stage PFC circuits. A digital controller, implemented using a low-cost microcontroller, dsPIC30F2020, will meet PFC and low light flicker. The experimental results validate the functionality of the proposed circuit.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.165-168
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• 2004

We have analyzed the cause of black "mura" and measured it in prism light-guide plate (LGP). Properties of components used in a back light. unit (BLU) have changed by Simulation Tool. We get major factor of black "mura" for improvement in prism LGP. For the improvement of black "mura", removal of brightness "mura" at input light part must precede preferentially because of reflection characteristics of the prism LGP. Removal of brightness "mura" is improved by changing of input light part in LGP and dispersion treatment.

• Journal of the Korean Institute of Telematics and Electronics
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• v.16 no.4
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• pp.22-26
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• 1979

Microlenses with an extremely small radius of curvature are efficiently use d to couple LED/laser diode light into optica1 fiber. We propose a Tapered lens for the highly efficient coupling of the optical fiber communication light souses into the fiber. Ray optical analysis shows that the maximum coupling efficiency is as high as 90 %, Tapered lens with optimum parameters are fabricated by using heating and pulling technique. Experiment shows that this new technique improves the coupling efficiency by two and four times for LED and laser diode, respectively, as compared with the simple flat - end coupling.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.155-161
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• 1997

This Expriment is performed to describe the properties of the freezing-thawing and to find the method to enhance the freezing-thawing resistance of the high strength light weight aggregates concrete. For this purpose, we made 8 kinds of specimen of concrete mold. The light weight coarse aggregate concrete which contained AE was appeared in good condition and its durability index was more than 90% by the buffer action which owing to entained air. The light weight aggregates concrete which admixture of silca fume, was appeared that the durability index was 46.74% in spite of its high strength. I might conclude that the most important factor for freezing-thawing resistance of high strength light weight aggregate concrete is the entrained air.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.340-340
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• 2016

We have prepared alumina (Al2O3) doped zinc oxide (AZO) films by DC magnetron sputtering (MS) technique and obtained higher self surface texturing at a high target angle (f). We have characterized the films and applied it as a front electrode of a single junction amorphous silicon solar cell. At a lower f the deposited films show higher values of optical gap (Eg), charge carriers mobility & concentration, crystallite grain size and wider wavelength range of transmission. At higher target angle the sheet resistance, surface roughness, haze factor etc for the films increase. For f=72.5o the haze factor for diffused transmission becomes 6.46% at 540 nm wavelength. At f=72.5o the material shows a reduction in crystallinity and evolution of a hemispherical-type sub-micron surface textures. A Monte Carlo method (MCM) of simulation of the AZO film deposition shows that such an enhanced self-surface texturing of the films at higher f is possible.

• Korean Institute of Interior Design Journal
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• no.11
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• pp.31-37
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• 1997

This study intens to provide available guideline of useful plants in interior and be used by designer. It focuses on evaluating the character of plants, the method of installation and the form of composition for suitable design of using plants. The study finds out that using plants in interior are necessary positively by 94% respondents. And results of factor analysis are that plants are needed for emothional stability(factor 1), visual charming(factor 2), and educational effection(factor 3). According to job, the group of students is visual charming (P=0.0037), the public servants and housewives is educational effection(p=0.0029). The most available space of plants as follows : Department(30.5%), Hotell(26.3%), House and Restuarant(12.7%). It has been identified that the public institution and commercial space are much indused plants. The most indused plants in house is ordered that the veranda, the living room, the entrance. This result is concerned about relation of natural light plants. The repondants reply that the favorite arrangement style is the corner form(63%), the center garden form(52.1%), the large planter(19.7%), the planter box(11.3%). They respond that they are more favorite light green color than dark, and mono color than mixture color. Finally, interior Designers should be understood the functional and aesthetic elements and the special interest about plants for developing desigv.

• Journal of Plant Biotechnology
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• v.32 no.4
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• pp.307-311
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• 2005

The anthocyanin biosynthesis in callus culture of purple sweet potato (Ipomoea batatas L. cv. Borami) was investigated under growth in different light intensity and light emitting diodes (LED) treatment. Pigmented calli were induced from leaf explants cultured on MS agar medium supplemented with $0.5\;{\mu}M$ 2,4-D under light condition. The color value of these calli extracted after $2{\sim}4$ weeks of cultures was $0.4{\sim}0.5\;mg/mL$. Irradiation intensity is an important factor for anthocyanin biosynthesis. The optimal anthocyanin accumulation occurred on light intensity of 3000 lux. Light irradiation of 3000 lux and blue light treatment for 2 h resulted in a significant enhancement of anthocyanin accumulation. This value was 1.4 fold that the control.

• Korean Institute of Interior Design Journal
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• no.13
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• pp.130-138
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• 1997

This study is to present the visual phenomenon of natural light in the interior space. The continuously changing natural light define the visual phenomenon of the architectural space. First, the objective of this study was finding the importance of the visual phenomena which were generated from correlating natural right with the interior space. And the second was to categorize the factors of the visual phenomenon which can be useful factors for modern interior design practice. As a result of this study, two visual phenomena were classified. First; territorial phenomenon: dividing, partitioning, and sectioning by natural light, Second; phenomena by the inflow methods of natural light; a) by direct inflow; transparency, expansion, and floating, b) by filtering fixtures; the architectural structure, color, and the transluscent material, c) by dramatic spacial present of natural light, d) by the sense of direction of naturel light; continuity, and transformatiov. Found and classified each factor is not presented by itself, rather compounded forms. Because of the limited analysis of modern buildings, these found visual factors can not represent all phenomena. But if we practice these finding factors to design present interior space, it is sure of being very valuable factors to re-introduce the overlooked natural light into interior space.

• Journal of Ecology and Environment
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• v.45 no.4
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• pp.218-227
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• 2021

Background: Artificial light at night has recently been identified as a major factor adversely affecting global insect diversity. Here, we compared the insect diversity in Gwangneung Forest Biosphere Reserve, specifically in the Korea National Arboretum (with no artificial light at night), with that of three nearby urban sites with a gradient of artificial light at night (five locations at each site). We analyzed the effects of the artificial night lighting index, mean annual temperature, and field light intensity (lux) at night on the insect community structure. Results: The urban sites generally exhibited higher species richness and abundance as well as clear indicator species compared with the control site. The size distribution of the collected insects markedly differed between the control and the three urban sites. The abundance of herbivorous and omnivorous insects increased and decreased, respectively, with the increase in light intensity. Species richness of herbivorous and omnivorous insects was likely correlated with the field light intensity at night and artificial night lighting index, respectively. Conclusions: This study demonstrates the association between nighttime environment and marked changes in insect community structure and revealed consequent transition of ecosystem services by changes in trophic group composition.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1760-1768
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• 2022

When gamma-camera sensor modules, which are key components of radiation imagers, are derived from the coupling between scintillators and photosensors, the light collection efficiency is an important factor in determining the effectiveness with which the instrument can identify nuclides via their derived gamma-ray spectra. If the pixel area of the scintillator is larger than the pixel area of the photosensor, light loss and cross-talk between pixels of the photosensor can result in information loss, thereby degrading the precision of the energy estimate and the accuracy of the position-of-interaction determination derived from each active pixel in a coded-aperture based gamma camera. Here we present two methods to overcome the information loss associated with the loss of photons created by scintillation pixels that are coupled to an associated silicon photomultiplier pixel. Specifically, we detail the use of either: (1) light guides, or (2) scintillation pixel areas that match the area of the SiPM pixel. Compared with scintillator/SiPM couplings that have slightly mismatched intercept areas, the experimental results show that both methods substantially improve both the energy and spatial resolution by increasing light collection efficiency, but in terms of the image sensitivity and image quality, only slight improvements are accrued.