• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회A
• /
• pp.1343-1348
• /
• 2008

LEDs which have many merits are widely used in the field of light devices, and have rapidly replaced old light devices such as incandescent or fluorescent lamps. Long life, on the order of 50,000 to 100,000 hours, is one of the key features of light emitting diodes(LEDs) that has attracted the lighting community to this technology. High Power white LEDs have yet to demonstrate this capability. This paper planed accelerated life test that has two factor(temperature, current) and two levels. Finally, using ALTA programs, we estimated the common shape parameter of Weibull distribution, life-stress relationship, B10 life and accelerating factors.

• 패션비즈니스
• /
• 제25권1호
• /
• pp.133-149
• /
• 2021

This study presents a new fashion wearable product, a classical music stage costume design, using an Arduino LilyPad that can control light-emitting diodes(LEDs) and a sound sensor that can set an environmental range of LED light. As a theoretical background, LED fashion design research and stage costume design research status were reviewed, and Arduino LilyPads, sensors, LEDs, and batteries required for LED stage costume production were investigated. Based on prior research, the LED stage costume design for the soprano stage was presented in a three-step process of design planning, development, and production, and an actual prototype was produced. This process produced meaningful information and materials for making clothes with the added function of a wearable computer. In particular, fashion designers or fashion majors can easily access the Arduino LillyPad and use not only LEDs, but other light emitting materials. It is expected that it will be used as a basic material for the use of the Arduino LillyPad that can develop new creations that have been utilized.

• 한국광학회지
• /
• 제35권3호
• /
• pp.95-106
• /
• 2024

일반 백색 LED의 연색성을 보완하기 위해 적색 양자점을 선택적으로 활용함으로써 고연색성 조명을 구현하는 연구가 최근 활발하다. 본 논문에서는 최근 이루어지고 있는 원격 양자점 부품 연구 및 이를 활용한 고연색성 조명 개발의 현황에 대해 소개한다. 특히 양자점 부품이 배치되는 조명의 광구조 최적화에 있어서 중요하게 고려해야 할 다양한 요소를 집중적으로 논의함으로써 향후 고연색성 조명 연구의 방향 및 전망까지 다루고자 했다.

• 한국자원식물학회:학술대회논문집
• /
• 한국자원식물학회 2018년도 추계학술대회
• /
• pp.109-109
• /
• 2018

Bacillus subtilis B22, a chemotrophic and aerobic bacterial strain was isolated from homemade kimchi, identified by 16S rRNA gene sequencing. B22 was primarily screened by biochemical, carbon source utilization tests. B22 was used to produce pectinase and ${\beta}$-glucosidase by submerged fermentation under different light sources. B22 was incubated in pectin media and basal media (pH 7.0) under blue, green, red and white light-emitting diodes (LEDs), fluorescent white light, and in darkness at $37^{\circ}C$, orbital shaker 150 rpm for 24 hours. Fermentation under blue LEDs maximized pectinase production ($71.59{\pm}1.6U/mL$ at 24 h) and ${\beta}$-glucosidase production ($56.31{\pm}1.6U/mL$ at 24 h). Further, the production of enzyme increased to pectinase ($156{\pm}1.28U/mL$) and ${\beta}$-glucosidase ($172{\pm}1.28U/mL$) with 3% glucose as a carbon source. Activity and stability of the partially purified enzymes were higher at pH 6.0 to 8.0 and $25-55^{\circ}C$. The effect on the metal ions $Na^+$ and $K^+$ and (moderateactivity) $Mn^{2+}$ and $Ni^{2+}$ increased activity, while $Hg^{2+}$, $Cu^{2+}$, $Fe^{2+}$, and $Fe^{2+}$ inhibited activity. EDTA, phenylmethylsulfonyl fluoride and 5,5-dithiobis (2-nitrobenzoicacid) reduced activity, while tetrafluoroethylene and 1,10-phenanthroline inhibited activity. The amylase was highly tolerant of the surfactants TritonX-100, Tween-20, Tween-80 and compatible with organic solvents methanol, ethanol, isoamylalcohol, isopropanol, t-butylalcohol and the oxidizing agents hydrogen peroxide, sodium perborate and sodium hypochlorite, although potassium iodide and ammonium persulfate reduced activity. These properties suggest utility of pectinase and ${\beta}$-glucosidase produced by B. subtilis B22 under blue LED-mediated fermentation for industrial applications.

• Transactions on Electrical and Electronic Materials
• /
• 제11권5호
• /
• pp.238-241
• /
• 2010

The purpose of this study is to solve the problems of radio frequency bandwidth frequency depletion, confusion possibilities, and security that are in current wireless communications systems, and to confirm the possibility of applying those solutions for the next generation network. To solve the problems of the current wireless communications system, a visible light communications system for power line communication (PLC) via 8-bit microcontroller is created and the capacity is analyzed. The exclusive PLC chip APLC-485MA, an 8-bit ATmega16 microcontroller, high brightness 5pi light emitting diodes (LEDs), and the LLS08-A1 visible light-receiving sensor were used for the transmitter and receiver. The performance was analyzed using a designed program and an oscilloscope. The voltage change was measured as a function of distance from 10-50 cm. Blue LEDs showed the best performance among the measured LED types, with 0.47 V of voltage loss, but for a distance over 50 cm, precise data was not easy to obtain due to the weak light. To overcome these types of problems, specific values such as the changing conditions and efficiency value relevant to the light emitting parts and the visible light-receiving sensor should be calculated, and continuous study and improvements should also be realized for better communication conditions.

• Bulletin of the Korean Chemical Society
• /
• 제26권5호
• /
• pp.855-858
• /
• 2005

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2011년도 춘계학술발표대회
• /
• pp.23.2-23.2
• /
• 2011

This presentation will include an overview of III-Nitride LED technology, applications, key areas for future improvements, challenges such as efficiency droop. GaN-based high-power light-emitting diodes (LEDs) suffer from high-current loss mechanisms that lead to a significant decrease in internal quantum efficiency at high drive currents, a well-known phenomenon commonly referred to as efficiency droop. Although many attempts have been made to uncover this LED's darkest secret, there is still a lack of consensus on the dominant mechanism responsible for this detrimental phenomenon. In this presentation, proposed origins and corresponding solutions to the droop-causing mechanisms will be reviewed and discussed.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
• /
• pp.52-54
• /
• 2008

The authors investigated the InGaN/GaN multi-quantum well blue light emitting diodes with the implements of the photonic crystals fabricated at the top surface of p-GaN layer or the bottom interface of n-GaN layer. The top photonic crystals result in the lattice-dependent photoluminescence spectra for the blue light emitting diodes, which have a wavelength of 450nm. However, the bottom photonic crystal shows a big shift of the photoluminescence peak from 444 nm to 504 nm and played as a role of quality enhancement for the crystal growth of GaN thin film. The micro-Raman spectroscopy shows the improved epitaxial quality of GaN thin film.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2012년도 추계총회 및 학술대회 논문집
• /
• pp.171-171
• /
• 2012

In this study, we fabricated the high-brightness AlGaInP-based red light emitting diodes (LED)s using by direct printing technique and inductive coupled plasma (ICP) reactive ion etching (RIE). In general, surface roughening was fabricated by wet etching process to improve the light extraction efficiency of AlGaInP-based red LED. However, a structure of the surface roughening, which was fabricated by wet etching, was tiled cone-shape after wet etching process due to crystal structure of AlGaInP materials, which was used as top-layer of red LED. This tilted cone-shape of surface roughening can improve the light extraction of LED, but it caused a loss of the light extraction efficiency of LED. So, in this study, we fabricated perfectly cone shaped pattern using direct printing and dry etching process to maximize the light extraction efficiency of LED. Both submicron pattern and micron pattern was formed on the surface of red LED to compare the enhancement effect of light extraction efficiency of LEDs according to the diameter of sapphire patterns.After patterning process using direct printing and ICP-RIE proceeded on the red LED, light output was enhanced up to 10 % than that of red LED with wet etched structure. This enhancement of light extraction of red LED was maintained after packaging process. And as a result of analyze of current-voltage characteristic, there is no electrical degradation of LED.

• ALGAE
• /
• 제24권2호
• /
• pp.121-127
• /
• 2009

The unicellular green alga, Haematococcus pluvialis, accumulates the highest level of astaxanthin among knownastaxanthi.n-producing organisms. Light is the most important factor to induce astaxanthin by H. pluvialis. BIue andred LEDs, whose ${\lambda}_{max}$'s are 470 and 665 nm, respectively, were used for internally illuminated light sources.Fluorescent lamps were also used for both internal and external illumination sources. The astaxanthin levels in thesevarious lighting systems were analyzed and compared each other. The cultures under internally illuminated LEDsaccumulaled 20% more astaxanthin than those under fluorescent lamp. Furthermore, LEDs generated much lessheat than the fluorescent lamps, which gives one more reason for the LEDs being a suitable internal Light source forastaxanthin induction. The results reported here would lead novel designs of photobioreactors with improvementsof illumination methods for high level of astaxanthm production. The maximum astaxanthin concentrations as wellas the astaxanthin yield per supplied photon were increased by at least 20% when blue or red LEDs were supplied.