• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.3
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• pp.16-25
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• 2013

Now it's a trend to install a series of white fluorescent light and orange high pressure sodium lamps because tunnel lighting should be opaque to the safety of drivers from soot, dust, humidity, and fog. Also fluorescent lighting is replaced to LED due to the fact that it improves amenity and object recognition and LED lighting has gradually been improved its nature. In this paper, we have implemented the circuits of the yellow series of high-pressure sodium lamps and white series of LED lights at one board to improve the transparency and recognition of objects. It is possible for inductive high-pressure sodium lamps and the capacitive LED drivers to circuit without power factor compensation. Two circuit parts share only a small number of parts, so low cost LED drivers compared to conventional ones are possible. Therefore, the implementation of the hybrid lighting with high-pressure sodium lamps and LED lights that can be driven at the same time by one driving circuit is possible. The LED capacitive power factor was 0.91 while individually implemented the sodium lamp power factor was 0.98. It shows not only the 2% improvement of hybrid forms but also the efficiency and THD.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.1
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• pp.86-92
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• 2019

Although perylene bisimide derivatives have advantages such as excellent thermal stability and high luminance efficiency, they have poor solubility characteristics in organic solvents. In this research, in order to improve the solubility characteristics, we prepared perylene bisimide derivatives (1C) and (2C) with swallow-tail substituted imide, which is known to lead to excellent solubility. The structures and properties of swallow-tail perylene bisimide (1C) and (2C) were analyzed by $^1H-NMR$, FT-IR, UV/Vis spectroscopy, and thermogravimetric analysis (TGA). The maximum absorption wavelengths of (1C) and (2C) in the UV/Vis spectrum were 558 nm and 556 nm, respectively, and the maximum emission wavelengths were 602 nm and 600 nm, respectively. In the TGA, (1C) demonstrated good thermal stability with less than 5 wt% weight loss up to $242^{\circ}C$. In the solubility test, (1C) and (2C) exhibited solubilities of more than 5 wt% in chloroform, ethyl acetate, and dimethylformamide, but not in methanol. When the compounds (1C) and (2C) were mixed with PMMA (polymethyl methacrylate), thin films showed peaks at 679 nm and 677 nm, respectively, in the photoluminescence spectra. (1C) was found to be a possible candidate as red organic phosphor for hybrid LEDs.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.1
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• pp.91-101
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• 2017

In this study, we conducted the preliminary research for high speed laser cutting of LED module. In particular, the feasibility of ultra-high speed laser cutting of 100 mm/s which exceeds the cutting speed of conventional dicing saw was examined. For this, copper/ceramic and silicone/ceramic hybrid substrates, which are the components of the LED module, were fabricated, and the surface morphology, surface roughness and flexural strength of the laser-cut samples were investigate and compared with the dicing-cut samples. To investigate optimal laser cutting conditions for hybrid substrates, the effects of various laser cutting conditions on cutting surface characteristics were studied using single ceramic and copper substrate. Optimal laser cutting conditions of the hybrid substrates were the use of Ar assist gas, high laser power and high assist gas pressure. Comparing the cutting surface of the hybrid substrates, the surface characteristics of the laser-cut samples are slightly inferior to those of the dicing-cut samples. The average surface roughness of the laser-cut samples was about $9{\mu}m$, and that of the dicing-cut samples was about $4{\mu}m$. However, considering very low cutting speed (3 mm/s) of the dicing saw, the surface morphology of the laser-cut sample was relatively uniform, and the surface roughness was not much different from that of the dicing-cut sample. The flexural strength of the laser-cut samples was equivalent to or slightly inferior to the flexural strength of dicing-cut samples. However, if the laser processing conditions are sufficiently optimized, the ultra-high speed laser cutting of the LED module will be possible.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.11
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• pp.6-17
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• 2015

In this paper, colors of broadcast lightings composed of Red, Green, and Blue LED(Light Emitted Diode) can be linearly and quantitatively controlled in low illuminance. Because LED cannot emit uniform illuminance in low illuminance, the colors of RGB LED are unmixable. Furthermore, the illuminances are nonlinear with the dimming values of the RGB LED due to the nonlinearity of the output illuminance with the current through the LED. This nonlinearity generated errors of the target colors and illuminances. The proposed algorithm set up the target colors, which is expressed by the color coordinates in CIE 1931 color space, and the target illuminances. Then the illuminances of RGB LED were calculated using color mixing theory. The calculated illuminances determined the dimming values of the RGB LED for transmission via DMX512 communication. After the broadcasting lighting received the dimming values of the RGB LED via DMX512 communication,.RGB LED can emit target color and illuminance, and be controlled by calculating the PWM(Pulse Width Modulation) duty ratio of the hybrid LED driver which be considered the nonlinearity for the illuminances of the LED. As a result, the proposed algorithm can linearly and quantitatively control the colors and illuminances in full range of illuminance. Then we verify experimentally that the errors of the emitted color coordination x, y and illuminance are 2.27%, 3.6% and 1.5%, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.480-481
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• 2012

LED (Light Emitting Diode)는 친환경적이며 고수명 등의 여러 장점을 가지고 있어서 액정디스플레이의 광원으로 널리 사용되고 있다. 그러나 LED 제품을 제조하기 위해서는 칩, 패키지, 모듈, 시스템으로 구성된 4단계의 복잡한 제조공정을 거쳐야 하므로 가격이 높은 단점이 있다. 이를 개선하기 위해서 패키지, 모듈, 시스템의 3단계의 공정을 하나로 통합한 hybrid LED package(HLP) 개념이 제시되었다. HLP는 LED chip을 PCB에 직접 실장한 뒤 초정밀 가공 및 성형 기술을 활용하여 일체형 광학패턴을 인가함으로써 공정을 단순화하면서도 광효율을 향상시킬 수 있다. 이에 본 연구에서는 다구찌 실험계획법을 사용하여 디스플레이에서 중요시되는 휘도를 높일 수 있는 일체형광학패턴 형상 최적화를 실시하였으며, 최적화된 일체형 광학패턴을 제조하기 위한 초정밀 가공 및 성형기술을 개발하였다. 최적화 결과 높이 25um, 꼭지각 90도의 음각형태의 사각피라미드 패턴이 최적형상으로 결정되었으며, 패턴이 없을 때와 비교하여 휘도가 약 32.3% 높아지는 것으로 나타났다. 이러한 일체형 광학패턴을 제품으로 구현하기 위하여 초정밀 절삭기술을 활용하여 마스터 금형을 제작하였다. 최종적으로 사출성형을 통해 일체형 광학패턴을 제작하게 되는데 이때 사출기 내부 공기흐름 및 진공도를 최적화함으로써 패턴 내부에 불필요한 기포가 발생하지 않도록 하는데 성공하였다. 이를 통해 생산성이 높은 사출성형으로 HLP 제품을 양산할 수 있는 가능성을 확인하였고, 추후에는 실제 제품을 제작하는 연구를 수행할 예정이다.

• ETRI Journal
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• v.33 no.6
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• pp.864-870
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• 2011

As an isotropic conductive adhesive, that is, a hybrid Cu paste composed of Cu powder, solder powder, and a fluxing resin system, has been quantitatively characterized. The mechanism of an electrical connection based on a novel concept of electrical conduction is experimentally characterized using an analysis of a differential scanning calorimeter and scanning electron microscope energy-dispersive X-ray spectroscopy. The oxide on the metal surface is sufficiently removed with an increase in temperature, and intermetallic compounds between the Cu and melted solder are simultaneously generated, leading to an electrical connection. The reliability of the hybrid Cu paste is experimentally identified and compared with existing Ag paste. As an example of a practical application, the hybrid Cu paste is used for LED packaging, and its electrical and thermal performances are compared with the commercialized Ag paste. In the present research, it is proved that, except the optical function, the electrical and thermal performances are similar to pre-existing Ag paste. The hybrid Cu paste could be used as an isotropic conductive adhesive due to its low production cost.

• Macromolecular Research
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• v.10 no.3
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• pp.174-177
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• 2002

Proton-conducting hybrid materials composed of silica and Nafion polymer were prepared from the sol-gel synthesis of silica in aqueous Nafion solution. The compositions of hybrid proton conductors were adjusted with the changing ratios of tetraethyl orthosilicate to Nafion. The thermal analysis, FTIR, SEM, and X-ray diffraction studies have proved the formation of Nafion/silica hybrid materials and no remarkable phase separation was observed, which led to an assumption that the macromolecular chain of silica and Nafion was homogeneously interlaned.

• Korean Journal of Optics and Photonics
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• v.30 no.4
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• pp.142-145
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• 2019

Normally, a corner cube retroreflector (CCRR) sheet is used as a retroreflective mirror array (RRMA) in a volumetric display. Each CCRR unit reflects light in the retroreflective direction, which is parallel to the incident light, and it makes a blurred image, as it shifts the position of light within its dimensions. Adopting a "curved planar wall" and "parabolic focusing" (x-axis), a hybrid-t(transverse direction)-RRMA is proposed, to improve the image quality and brightness. The improvement of image contrast is achieved by tuning a "linear v-shaped groove" structure to a "parabolic v-shaped groove". Also, the system has been simplified and the brightness enhanced 4 times by removing the half mirror.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.9
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• pp.577-582
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• 2017

The white light of a hybrid LED is obtained by using red and green organic fluorescent layers made of polymethylmethacrylate (PMMA) films, which function as color down-conversion layers of blue light-emitting diodes. In this research, we studied the fluorescence properties of a red organic fluorophore, employing perylene bisimide derivatives applicable to hybrid LEDs. The solubility, thermal stability, and luminous efficiency are important characteristics of organic fluorophores for use in hybrid LEDs. The perylene fluorescent compounds (1A and 1B) were prepared by the reaction of 4-bromophenol and 4-iodophenol with N,N'-bis(4-bromo-2,6-diisopropylphenyl)-1, 6,7,12-tetrachloroperylene-3,4,9,10-tetracarboxyl diimide (1) in the presence of dimethyl formaldehyde (DMF) at $70^{\circ}C$. The synthesized derivatives were characterized by using $^1H-NMR$, FT-IR, UV/Vis absorption and PL spectra, and TGA analysis. Compounds 1A and 1B showed absorption and emission at 570 nm and 604 nm in the UV/Vis spectrum. We also documented favorable solubility and thermal stability characteristics of the perylene fluorophores in our work. Perylene fluorophore 1, with the 4-bromophenol substituent 1A, exhibited particularly good thermal stability and solubility in organic solvents.

• Korean Journal of Optics and Photonics
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• v.27 no.2
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• pp.73-80
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• 2016

In this paper, we report the results of a study on the design and fabrication of a light-guiding plate (LGP) using a hybrid light-emitting diode (LED) and sunlight source that can be applied to a photobioreactor. LGP patterns for the LED source were designed and engraved on an LGP, together with previously reported patterns for a sunlight source. A control system for the hybrid LGP was designed to maintain the output photon flux density (PFD) from the LGP at a constant value. When the target value of the output PFD was set to $70{\mu}E/(m^2{\cdot}s)$, the error range of the output PFD was found to be within ${\pm}2%$.