• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
• /
• pp.1529-1530
• /
• 2007

The manganese co-doped $Ca_8Mg_1(SiO_4)_4Cl_2:Eu^{2+}$,$Mn^{2+}$ phosphor was synthesized by solid-state reaction and its photoluminescence characteristics were investigated. The synthesized phosphor show two emission spetrums: green band of 512nm and yellow band of 550nm. White light-emitting diodes (LEDs) were fabricated through combination of a 405nm-emitting InGaN chip and a synthesis phosphor in a single package. Under 20mA current, its CIE chromaticity coordinates are x=0.40 and y=0.45 and a color temperature of 4053K.

• 대한화장품학회지
• /
• 제48권3호
• /
• pp.245-254
• /
• 2022

본 연구에서는 655 nm에서 저출력 레이저와 625 ± 5 nm와 850 ± 10 nm에서 파장을 방출하는 LED를 이용한 복합 광선 요법이 탈모 및 두피에 나타나는 효능을 조사하고자 하였다. 이번 연구에는 총 33 명의 시험대상자가 등록되었다. 각 시험대상자는 Low-level laser therapy (LLLT)와 light-emitting diode (LED) 기기를 매일 10 min 씩 12 주간 두피와 모발에 사용했다. LLLT와 LED 기기를 사용한 지 12 주 후, 두피의 붉은기, 탄력, 수분 함량에서 상당한 개선이 있었으며, 모발의 윤기와 인장 강도, 탈락 모발 수가 개선되었다. 시험대상자가 시험 기기를 사용하는 기간 동안 특별한 피부 이상반응에 대한 보고는 없었다. LLLT와 LED를 이용한 복합 광선 요법은 탈모와 두피 상태 개선에 효과적인 요법임이 입증되었다.

• 한국환경농학회지
• /
• 제30권4호
• /
• pp.382-389
• /
• 2011

BACKGROUND: Light-emitting diodes (LEDs) with lower electric cost and the specific wavelength have been considering as a novel light source for plant production in greenhouse conditions as well as in a closed culture system. Supplementary lighting for day-length extension was considered as light intensity, light quality, and/or photoperiod control on plant growth and development. Effects of supplementary blue or red LED radiation with lower light intensity on growth of Ageratum (Ageratum houstonianum Mill., cv. Blue Field), African marigold (Tagetes erecta L., cv. Orange Boy), and Salvia (Salvia splendens F. Sello ex Ruem & Schult., cv. Red Vista) were discussed during sunrise and sunset twilight in the experiment. METHODS AND RESULTS: Supplementary lighting by blue and red LEDs for 30 (Treatment B30; R30) or 60 (Treatment B60; R60) min. per day were established in greenhouse conditions. Photosynthetic photon flux for supplementary radiation was kept at $15{\mu}mol\;m^{-2}\;s^{-1}$ on the culture bed. Natural condition without supplementary light was considered as a control. The highest shoot and root dry weights were shown in African marigold exposed by red light for 60 min. per day. Supplementary blue and red lighting regardless of the radiation time significantly stimulated development of lateral branches in African marigold. Stem growth in Ageratum and Salvia seedlings was significantly promoted by red radiation as well as natural light. CONCLUSIONS: Extending of the radiation time at sunrise and sunset twilight using LEDs stimulated reproductive growth of flowering plant species. Different characteristics on growth under supplementary blue or red lighting conditions were also observed in the seedlings during supplementary radiation.

• 패션비즈니스
• /
• 제25권1호
• /
• pp.51-64
• /
• 2021

The purpose of this study was to develop smart bags that combining fashion-specific trends and smart information technologies such as light-emitting diodes(LED) and optic fibers by grafting marquage techniques that have recently become popular as part of eco-fashion. We applied e-textiles by designing leather tote bags that could show off LED luminescence. A total of two tote bags, a white-colored peacock design and a black-colored paisley design, divided the LED's light-emitting method into two types, incremental lighting and random light-emission to suit each design, and the locations of the optical fibers were also reversed depending upon the design. The production of circuits for the LEDs and optical fibers was based on the design, and a flexible conductive fabric was laser-cut instead of wire line and attached to the circuit-line location. A separate connector was underwent three-dimensional(3D)-modeling and was connected to high-luminosity LEDs and optic fiber bundles. The optical fiber logo part expressed a subtle image using a white-colored LED, which did not offset the LED's sharp luminous effects, suggesting that using LEDs with fiber optics allowed for the expression of each in harmony without being heterogeneous. Overall, the LEDs and fiber optic fabric were well-harmonized in the fashion bag using marquage techniques, and there was no sense of it being a mechanical device. Also, the circuit part was made of conductive fabric, which is an e-textile product that feels the same as a thin, flexible fabric. The study confirmed that the bag was developed as a smart wearable product that could be used in everyday life.

• 한국유기농업학회지
• /
• 제21권4호
• /
• pp.659-668
• /
• 2013

The objective of this study was carried out to elucidate the effect of LEDs (light emitting diodes) irradiation in relation to early growth and inorganic elements in leaf lettuce (Lactuca sativa L. 'Chung Chi Ma'). In morphological changes of leaves, shoot elongation and hypocotyl length showed poor growth in red light irradiation, while the red+blue light irradiation induced shorter plant height and much greater leaf numbers resulting in increased fresh weight. In change of the Hunter's color and SPAD values, lettuce seedlings grown under in red+blue and fluorescent light irradiation had a higher $a^*$ value, otherwise SPAD values were not changed in these light irradiations. Interestingly, relative chlorophyll contents showed 1.8 times increased redness in the treatment of red+blue light irradiation. Inorganic element (N, Ca, Mg, Mn, and Fe) and ascorbic acid contents were increased in lettuce plants grown under LEDs light irradiation compared to those of lettuce grown under the fluorescent light which showed higher P and Mn contents. In conclusion, it is considered that red+blue light irradiation which stimulates growth and higher nutrient uptake in leaf lettuce could be employed in containers equipped with LEDs.

• Current Optics and Photonics
• /
• 제3권6호
• /
• pp.485-495
• /
• 2019

Photobiomodulation (PBM) using organic light emitting diodes (OLEDs) surface light sources have recently been claimed to be the next generation of PBM light sources. However, the differences between light emitting diodes (LEDs) and OLED mechanisms in vitro and in vivo have not been well studied. In vivo mouse models were used to investigate the effects of OLED irradiation on cellular function and cutaneous wound healing compared to LED irradiation. Mice in the LED- and OLED-irradiated groups were subjected to irradiation with 6 J/㎠ LED and OLED (630 nm), respectively, for 14 days after wounding, and some mice were sacrificed for the experiments on days 3, 7, 10, and 14. To evaluate wound healing, we performed hematoxylin-eosin and Masson's trichrome staining and quantified collagen density by computerized image analysis. The results showed that the size of the wound, collagen density, neo-epidermis thickness, number of new blood vessels, and number of fibroblasts and neutrophils was significantly influenced by LED and OLED irradiation. The tissue levels of interleukin (IL)-β, IL-6 and tumor necrosis factor (TNF)-α were investigated by immunohistochemical staining. LED and OLED irradiation resulted in a significant increase in the tissue IL-β and IL-6 levels at the early stage of wound healing (P < 0.01), and a decrease in the tissue TNF-α level at all stages of wound healing (P < 0.05), compared to the no-treatment group. The expression levels of the genes encoding vascular endothelial growth factor and transforming growth factor-beta 1 were significantly increased in LED and OLED-irradiated wound tissue at the early stage of wound healing (P < 0.01) compared to the no-treatment group. Thus, OLED as well as LED irradiation accelerated wound healing by modulating the synthesis of anti-inflammatory cytokines and the expression levels of genes encoding growth factors, promoting collagen regeneration and reducing scarring. In conclusion, this suggests the possibility of OLED as a new light source to overcome the limitations of existing PBMs.

• KSBB Journal
• /
• 제28권3호
• /
• pp.170-176
• /
• 2013

The purpose of this study was to determine optimum condition of Pavlova lutheri and Phaeodactylum tricornutum. Detailed studies were carried out on the effects of various wavelengths of light-emitting diodes (LEDs), light intensities and air flow rations. For the Pa. lutheri, cell growth rates and maximum cell concentrations were similar regardless of wavelengths and air flow rates. Among the different light intensities, cell concentration increased when light intensity of red LED increased. For Ph. tricornutum, red LED was found to be the most effective light source, and light intensity of 3,100 Lux resulted in the most effective for the cultivation of Ph. tricornutum. Different air flow rates were tested to overcome shading effects due to denser cell concentration in the solution. Aeration of 0.8 vvm was determined to be the optimum aeration rate for the cultivation of Ph. tricornutum. Especially, five and two times greater cell concentrations of Pa. lutheri and Ph. tricornutum, respectively, were observed when air was applied.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제5권2호
• /
• pp.131-135
• /
• 2005

The effect of different surface passivation films on blue or green (465-505 nm) InGaN/GaN multi-quantum well light-emitting diodes (LEDs) die were examined. $SiO_2$ or $SiN_x$ deposited by plasma enhanced chemical vapor deposition, or $Sc_2O_3$ or MgO deposited by rf plasma enhanced molecular beam epitaxy all show excellent passivation qualities. The forward current-voltage (I-V) characteristics were all independent of the passivation film used, even though the MBE-deposited films have lower interface state densities ($3-5{\times}10^{12}\;eV^{-1}\;cm^{-2}$) compared to the PECVD films (${\sim}10^{12}\;eV^{-1}\;cm^{-2}$), The reverse I-V characteristics showed more variation, hut there was no systematic difference for any of the passivation films, The results suggest that simple PECVD processes are effective for providing robust surface protection for InGaN/GaN LEDs.

• Journal of Periodontal and Implant Science
• /
• 제50권4호
• /
• pp.251-259
• /
• 2020

Purpose: This randomized controlled study aimed to evaluate the effects of an electric toothbrush with 3 colors of light-emitting diodes (LEDs) on antiplaque and bleeding control. Methods: This randomized, placebo-controlled, double-blinded, parallel-group clinical trial included 50 healthy adults with gingivitis, who were randomly assigned to 2 groups. The experimental group used electric toothbrushes with 3 colors of LEDs and the control group used the same electric toothbrush as the experimental group, but with LED sources with one-hundredth of the strength. The subjects used the electric toothbrush 3 times a day for 4 minutes each time. As clinical indices, bleeding on marginal probing (BOMP), the Löe-Silness gingival index (GI), and the Turesky-Quigley-Hein plaque index (QHI) were assessed at baseline, at 3 weeks, and at 6 weeks. Results: There were significant decreases in all clinical indices (BOMP, GI, QHI) in both the experimental and control groups compared to baseline at 3 weeks and at 6 weeks. In a comparison between the experimental and control groups, no statistically significant differences were observed for any clinical indices at 3 weeks (P>0.05). However, at 6 weeks, statistically significant differences were observed between the experimental and control groups in BOMP and GI, which are indicators of gingival inflammation (P<0.05). Conclusions: This study demonstrated that an electric toothbrush combined with 3-color LEDs reduced gingival bleeding and inflammation after 6 weeks.

• 한국광학회지
• /
• 제32권4호
• /
• pp.163-171
• /
• 2021

조명에 사용되는 일반적인 백색 발광 다이오드는 청색 발광 다이오드 위에 황색 형광체를 입힌 구조가 보편적이나 발광 스펙트럼상 짙은 적색 성분이 부족해서 조명의 연색성이 떨어지는 문제가 있다. 본 연구에서는 백색 발광 다이오드의 연색 특성을 개선하기 위해 적색 양자점 조명을 백색 조명의 확산판에 적용한 후 광학 시뮬레이션을 이용해 광구조를 최적화하고자 하였다. 양자점의 평균 자유 행정 및 확산판 내 TiO₂ 입자의 농도를 조절해 연색지수, 휘도 등 광특성을 조사했다. 대부분의 조건에서 연색지수는 90을 넘었고 이는 적색 양자점 필름의 적용이 일반적인 백색 발광 다이오드의 연색 특성을 개선하는 데 효과적인 방법임을 보여준다. 색좌표의 각도 의존성은 확산판과 조명 하단의 반사판 사이에 형성되는 광학적 공동 구조를 활용함으로써 제거할 수 있었는데 이는 공동 내 위치한 양자점 필름을 통한 빛의 다중 투과가 시야각에 따른 광경로의 차이를 줄였기 때문으로 해석된다.