• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.56-59
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• 2009

In the nineties the invention of the InGaN blue LED has innovated illumination technology. Currently LCD backlighting and more and more general lighting applications are based on white LEDs comprising of inorganic phosphors and blue emitting InGaN chip. Well established phosphor materials are ortho silicates and garnets like yellow emitting YAG:Ce. In our paper we demonstrate that garnet materials also allow for green light emission for both, general lighting and backlighting LED applications.

• Current Optics and Photonics
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• v.4 no.3
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• pp.247-252
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• 2020

Important determinants for selecting outdoor lighting are the color-rendering index (CRI) and scotopic-to-photopic (S/P) ratio of the lighting units. The higher the S/P ratio, the better energy savings and visual performance. In this study, CCT-tunable LED lighting units were optimized and fabricated by spectral combination of red, green, blue, and yellow LEDs. The measured results for RGB LEDs provided S/P ratios of 1.55~2.58 and those of RGBY LEDs gave 1.46~2.46 to the correlated color temperatures (CCTs) ranging from 2700 K to 6500 K, with CRI values of over 80 at the same time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2522-2527
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• 2011

Technology policy has a substantial impact on the diffusion of a new technology. This paper uses technology policy as a variable in the general epidemic model to quantify the effects of the policy on technology diffusion. The results obtained in this study, using data on solid-state technology diffusion in the U.S. indicate that technology policy plays a positive role in technology diffusion and provide a firm basis for understanding the relationship between technology policy and technology diffusion through the use of quantitative data.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.23-23
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• 2003

GaN-related semiconductors are of great technological importance for the fabrication of optoelectronic devices, such as blue and ultra violet light emitting diodes (LEDs), laser diodes, and photo-detectors. One of the most important applications of GaN-based LEDs is solid-state lighting, which could replace incandescent bulbs and ultimately fluorescent lamps. For solid-state lighting applications, the achievement of high extraction efficiency in LED structures is essential. For flip-chip LEDs (FCLEDS), the formation of low resistance and high reflective p-GaN contact is crucial. So far, a wide variety of different methods have been employed to improve the ohmic properties of p-type contacts to GaN. For example, surface treatments using different chemical solutions have been successfully used to produce high-quality ohmic contacts, Metallization schemes, such as Ta/Ti contacts to p-GaN, were also investigated. For these contacts, the removal of hydrogen atoms from the Mg atoms doped n the GaN was argued to be responsible for low contact resistances.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1350-1352
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• 2008

Research on down conversion phosphor materials is the key for the development of solid state lighting (SSL). Especially finding alternative red phosphor for white LEDs based on blue or NUV LEDs are important research task. Under this view, we have synthesized a series of $Eu^{3+}$ substituted $La_2W_{2-x}Mo_xO_9$ (x = 0 ~ 2, insteps of 0.1) red phosphor and characterized by X-ray diffraction (XRD) and photoluminescence. XRD results reveal a phase transition from triclinic to cubic structure for $x\;{\geq}\;0$. All the compositions show broad charge transfer band due to charge transfer from oxygen to tungsten/molybdenum and red emission due to $Eu^{3+}$ ions. Select compositions show high red emission intensity compared to the commercial red phosphor under NUV/blue ray excitation. Hence, this candidate can be possible red emitting phosphors for white LEDs.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.3
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• pp.1-6
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• 2004

Recently the examples of a designing a building-lighting to which LED, a solid state Lighting, is applied are increasing in number, but the development of lighting apparatus and the techniques applied to a designing lighting apparatus frequently don't fit to a new source of light. This essay refers to the matters relevant to the techniques for designing a lighting, which are controlled with a digital technology, and the effectiveness of a "Interactive-lighting technique" which has a ductility by a sensor with developing a digital source of light module and applying it to a real designing a building-lighting . In the negative aspect that a digital technology can standardize a space for a lighting, a "Interactive-lighting Technique", which detects an analogic change of nature through a sensor and produces it, can become a new alternative one.

• Journal of the Optical Society of Korea
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• v.16 no.3
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• pp.203-209
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• 2012

Visible light communications (VLC) use modern solid-state light-emitting diodes (LEDs) to broadcast information. Emerging white-light LEDs allow the combination of lighting and optical wireless communication in one optical source. In this paper, a new LED lighting design using one-chip-type white LEDs is proposed for efficient illumination and optical wireless communications under the existence of several obstacles. Lighting and communication performance are analyzed to show the effectiveness of the proposed LED lighting. Specifically, the signal-to-noise ratio considering intersymbol interference and the bit-error rate of variable pulse position modulation (VPPM) with dimming control are considered.

• Korean Journal of Materials Research
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• v.29 no.2
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• pp.116-120
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• 2019

We prepared $Y_3Al_5O_{12};Ce^{3+},Pr3^{+}$ transparent ceramic phosphor using a solid state reaction method. By XRD pattern analysis and SEM measurement, our phosphors reveal an Ia-3d(230) space group of cubic structure, and the transparent ceramic phosphor has a polycrystal state with some internal cracks and pores. In the Raman scattering measurement with an increasing temperature, lattice vibrations of the transparent ceramic phosphor decrease due to its more perfect crystal structure and symmetry. Thus, low phonon generation is possible at high temperature. Optical properties of the transparent ceramic phosphor have broader excitation spectra due to a large internal reflection. There is a wide emission band from the green to yellow region, and the red color emission between 610 nm and 640 nm is also observed. The red-yellow phosphor optical characteristics enable a high Color Rendering Index (CRI) in combination with blue emitting LED or LD. Due to its good thermal properties of low phonon generation at high temperature and a wide emission range for high CRI characteristics, the transparent ceramic phosphor is shown to be a good candidate for high power solid state white lighting.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.211-214
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• 2009

In this paper we will outline the opportunities for flexible OLED devices, both for display and solid-state lighting applications. We will present our recent data, and discuss future challenges, for low power consumption phosphorescent OLED technology fabricated on flexible substrates to enable a new generation of energy efficient electronic devices.

• Transactions of the KSME C: Technology and Education
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• v.5 no.1
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• pp.53-61
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• 2017

In this review paper, the trend for optical technology is described as the development of mechanical industries in the $21^{st}$ century. Optical technology has been essential in various industries such as mechanical, electronic industries as the convergence technology. Based on the roadmap of optical science and technology, 12 working groups are categorized as the technical point of view and most of them are closely related to mechanical industries. Especially, solid-state lighting, optical metrology and industrial laser processing are important technologies in precision engineering and manufacturing. This paper introduces these optical technologies and their technological issues to look into the development trends and expectation.