• 한국작물학회:학술대회논문집
• /
• 한국작물학회 2022년도 추계학술대회
• /
• pp.184-184
• /
• 2022

This study was aimed to evaluate the antioxidant activity and bioactive property of extracts from a purple-colored wheat variety 'Arriheuk' (Triticum aestivum L.) wheatgrass, affected by light emitting diode irradiation (LED). The wheatgrass was cultivated for 10 days after sowing in a growth chamber under the following LED conditions: R1B1 (Red:Blue = 1:1), R7B3 (Red:Blue = 7:3), and R3B7 (Red:Blue = 3:7). We examined antioxidant activity of the hot water extracts of wheatgrass using DPPH and ABTS free radicals scavenging assays. At the concentration of 10,000 ㎍/ml, the extract from R1B1 showed the highest DPPH free radical scavenging activity(79.29%), but its ABTS free radical scavenging activity was the lowest(32.0%). To evaluate bioactive property of the wheatgrass, we examined the change of natural killer (NK) cell activity affected by the wheatgrass extracts in vitro. At the concentration of 500㎍/ml, NK cell activity was most highly enhanced by the extract from R1B1(181.6%), and the activity was 176.1% (R7B3) and 144.6%(R3B7), respectively. These results suggest that the functional property of 'Arriheuk' wheatgrass would be enhanced by LED irradiation condition.

• 대한화학회지
• /
• 제47권4호
• /
• pp.370-375
• /
• 2003

보라색 발광 다이오드에 의해 여기되어 청색, 녹색, 적색을 발광하는 형광체로 각각 $BaMg_2Al_16O_27:Eu,\SrGa_2S_4:Eu$, ZnCdS:Ag,Cl 형광체를 선택하였다. 보라색 발광 다이오드의 발광에서 형광체에 의해서 완전히 흡수되지 않고 나오는 보라색 발광과 $BaMg_2Al_16O_27:Eu,\SrGa_2S_4:Eu$, ZnCdS:Ag,Cl 형광체에서 나오는 청색, 녹색, 적색 발광을 조합하여 사파장 백색 발광 다이오드를 만들었다. 사파장 백색 발광 다이오드의 발광 특성을 확인하였다.

• 한국전기전자재료학회논문지
• /
• 제14권2호
• /
• pp.145-151
• /
• 2001

In this study, blue light emiting, soluble PPV copolymers were synthesized by Witting reaction and characterized. ITO/copolymer/Ca and ITO/copolymer/A1 structured light emitting diodes(LED) were fabricated and their I-V characteristics were examined. Copolymers showed $\pi$-$\pi$ transition in UV-Vis./NIR spectra. The PL and abosorption spectrum showed the symmetric vibration modes with mirror images which means that copolymers are highly aligned. By introducing aliphatic hydrocarbon group on polymer main chain, the solubility of copolymers was improved and no significant effects of substituent were observed. The band offset of copolymers are well suited as light emitting material for LED application than monomer or oligomer does. THe band offset of copolymers is ∼3eV in PL spectrum and the threshold voltages of ITO/copolymer/Ca and ITO/copolymer/Al structured LED 3V, 12V respectively. In the case of ITO/copolymer/Ca LED, it is believed that the amount of electrons and holes is well balanced and the recombination of opposite charges occurs easily because the work functions of Ca and Al electrodes are 2.9 and 4.3eV respectively and the difference in barrier height between polymer and electrode was small.

• 한국기계가공학회지
• /
• 제13권4호
• /
• pp.121-129
• /
• 2014

This study was carried out to develop an efficient plant growth system that can be controlled by altering the wavelength and illumination using a LED module. If it is possible to develop a system that can be controlled in this manner, utilizing different characteristics in the meaningful wavelength band depending on the growth time or type of plant, the plant growth conditions can be optimized. In order to this, red, green, blue and white LEDs are arrayed in a rectangle, consisting of LED modules which can be combined with each other. Consequently, the array can be used to select the optimal light conditions with monochromatic red, green, blue and white LEDs, or mixed LEDs, for plant growth. Experiments on the characteristics of the wavelengths to evaluate the efficiency of the plant growth system were performed. The usefulness of the system was demonstrated through a cultivation test involving several special plants.

• Bulletin of the Korean Chemical Society
• /
• 제33권8호
• /
• pp.2523-2528
• /
• 2012

Green phosphors $(Zn_{1-a-b}M_aM^{\prime}_b)_xGa_yS_{x+3y/2}:Eu^{2+}$ (M, M' = alkali earth ions) with x = 2 and y = 2-5 were prepared, starting from ZnO, MgO, $SrCO_3$, $Ga_2O_3$, $Eu_2O_3$, and S with a flux $NH_4F$ using a conventional solidstate reaction. A phosphor with the composition of $(Zn_{0.6}Sr_{0.3}Mg_{0.1})_2Ga_2S_5:Eu^{2+}$ produced the strongest luminescence at a 460-nm excitation. The observed XRD patterns indicated that the optimized phosphor consisted of two components: zinc thiogallate and zinc sulfide. The characteristic green luminescence of the $ZnS:Eu^{2+}$ component on excitation at 460 nm was attributed to the donor-acceptor ($D_{ZnGa_2S_4}-A_{ZnS}$) recombination in the hybrid boundary. The optimized green phosphor converted 17.9% of the absorbed blue light into luminescence. For the fabrication of light-emitting diode (LED), the optimized phosphor was coated with MgO using magnesium nitrate to overcome their weakness against moisture. The MgO-coated green phosphor was fabricated with a blue GaN LED, and the chromaticity index of the phosphor-cast LED (pc-LED) was investigated as a function of the wt % of the optimized phosphor. White LEDs were fabricated by pasting the optimized green (G) and the red (R) phosphors, and the commercial yellow (Y) phosphor on the blue chips. The three-band pc-WLED resulted in improved color rendering index (CRI) and corrected color temperature (CCT), compared with those of the two-band pc-WLED.

• 한국산학기술학회논문지
• /
• 제15권5호
• /
• pp.3007-3013
• /
• 2014

본 연구의 목적은 블루 LED 기반의 치과용 스캐너를 이용하여 제작된 3차원 디지털 모형의 정확도를 평가하는 것이다. 본 연구를 위하여 20개의 동일한 석고 모형 제작 후 블루 LED기반의 치과용 스캐너를 이용하여 석고 모형과 동일한 20개의 3차원 디지털 모형을 제작하였다. 정확도를 평가하기 위해 두 집단의 모형을 대상으로 6개의 계측 거리를 지정한 후 측정하였다. 통계분석은 비모수 검정법인 윌콕슨 순위 합 검정법을 이용하여 비교 분석하였다(제1종 오류수준=0.05). 비록 모든 부위에서 디지털 모형이 석고 모형보다 작은 것으로 분석되었으나(p<0.05), 임상적 허용 수치를 벗어나지 않았다.

• Journal of Plant Biotechnology
• /
• 제42권2호
• /
• pp.104-110
• /
• 2015

본 연구는 다양한 LED광 처리가 상추의 생장상, 플라보노이드 생합성 관련 유전자들의 발현양상 및 플라보노이드 함량에 미치는 영향을 분석하였다. 상추의 생장상 분석에서 혼합광 처리가 단일 처리구보다 잎생장이 월등히 우수하였으며, 단일광내에서 청색광이 적색광보다 생체중이 높게 나타났다. LED광질에 따른 플라보노이드 생합성 관련 8개 유전자들의 발현을 분석한 결과 LsF3H와 LsDFR 유전자에서 혼합광 처리한 적상추에서 청상추보다 높게 나타났다. 또한 혼합광 처리가 단일광 처리보다 Gallic acid, Chlorogenic acidn, Quercetin 및 안토시아닌의 함량이 가장 높게 나타났다. 이상의 결과로부터 LED 광질에 따라 상추 생장과 발육차이를 보이며, 유전자의 발현 및 기능성 물질의 축적에 중요한 요인으로 작용하며, 기능성 물질의 축적을 유도하기 위해서는 적색과 청색의 혼합처리가 유용하리라 생각된다.

• 한국산학기술학회논문지
• /
• 제21권10호
• /
• pp.64-71
• /
• 2020

본 연구에서는 미세조류 Haematococcus pluvialis의 성장에 미치는 배양 배지와 광원의 영향을 평가하기 위해 제한 성분 배지인 Modified Bold's Basal Medium (MBBM) 와 상업용 액체 비료 배지인 Neo, 그리고 파장이 서로 다른 7개의 광원을 사용하여 H. pluvialis를 39일 동안 배양하고 성장률을 비교하였다. 그 결과 제한 성분 배지인 MBBM에서 H. pluvialis의 성장은 fluorescent light 광원에서 세포 성장이 가장 높게 나타난 반면, blue+red LED에서 세포 성장이 가장 낮게 나타났다. 상업용 배지인 Neo에서 H. pluvialis의 성장은 fluorescent light 광원에서 세포성장이 가장 높게 나타났으며, blue LED에서는 세포 성장이 가장 낮음이 확인되었다. 본 연구를 통해 MBBM 배지가 Neo 배지보다 우수한 결과를 나타내었으며 또한, MBBM 배지를 이용하여 fluorescent light에서 성장한 미세조류는 본 연구에서 가장 우수한 세포 성장 결과를 보였다. 이러한 결과는 이차대사산물 생산을 위한 H. pluvialis 배양에서 배지, 광원과 광량을 최적화한 것으로 미세조류 대량 배양에 기초 자료로써 유용하게 활용될 것이다.

• 보존과학회지
• /
• 제36권4호
• /
• pp.236-243
• /
• 2020

In this study, an accelerated aging experiment for fabric and paper was conducted using two light emitting diode(LED) sources with different wavelength characteristics, and the discoloration under each lighting type was examined. Hanji(Korean traditional paper) and related textiles showed more discoloration under blue LEDs, while the blue wool standard showed more discoloration under white LEDs. This, indicated that the deterioration varied depending on the sample color. The the effect of the light source on artifact deterioration was primarily related to the total radiation flux(expressed in mill watts), rather than the total luminous flux(expressed in lumens). In addition, the discoloration of the investigated artifacts was dependent on the color rendering of the lighting.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1996년도 추계학술대회 논문집
• /
• pp.274-277
• /
• 1996

This paper describes the realization of the full-color to the degree of nearest white light by compounding high brightness Red, Green and Blue LEDs with appropriate proportional index. Once these three colors; red, green and blue are mixed, they are genearlly additive mixing and produce white light color contrasted to negative mixing. The luminous efficiency is defined as the product of the efficiency(lm/w), which indicates the degree of perceptual response by the human eye to unit energy(W) of light emitted by an active display devises and as the conversion efficiency of the device from electric power consumed to optical energy produced. We will deduce the each number of LEDs theoretically and design several shapes of LED displays for the full-color. Finally theoretical predictions will be compared with the measured data with different type of display designs.