• Proceedings of the KIEE Conference
• /
• 1999.11d
• /
• pp.997-999
• /
• 1999

We fabricated white light-emitting organic electroluminescent device which have a mixed single emitting layer containing poly(N-vinylcarbazole)[PVK], tris(8-hydroxyquinoline)aluminum[Alq3] and poly(3-hexylthiophene)[P3HT] and investigated the emission properties of it. We expect to obtain a blue light from PVK, green light from Alq3 and red light from P3HT The fabricated device emits white light over 18V with slight orange light. We think that the energy transfer in a mixed layer occurred from PVK to $Alq_3$ and P3HT resulted in decreasing the blue light intensity from PVK. With mixing of N, N'-diphenyl-N, N'-(3-methylphenyl)-[1,1'-biphenyl]-4, 4'-diamine[TPD], hole transport material, to the emitting layer, the luminance intensity of device was increased 50 times than that of the device which not contain TPD. We find that the efficiency of the white light electroluminescent device can be improved by injecting electron more effectively and blue light need to improve the color purity of white light.

• KSBB Journal
• /
• v.19 no.4
• /
• pp.257-262
• /
• 2004

Recently, there is a growing interest in microalgae and the use of microalgae focused on the production of various high value metabolite used in food, pharmaceuticals and cosmetics. The key limiting factor in high density algal cultivation is the light and algal growth is defined by light intensity and light penetration depth into the culture medium. The effect of light with various light paths, S/V ratios, light intensities, and 50% duty cycle on the growth of microalgae was examined to enhance microalgal biomass productivity and photosynthetic efficiency. We confirmed that the utilization of efficient light energy was obtained from 4 cm of diameter, 57.6% of S/V ratio, 62 ${\mu}$mol/㎡/s of light intensity.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.6
• /
• pp.19-25
• /
• 2007

We studied prism design method for actual light source that have bulk in order to accomplish particular intensity distribution. When we know incidence angle and try to send ray to given direction, numerical formula that yields prism vertical angle, and then vertical angles were calculated sequentially. After analyzing problem that supposing to point light source, supplemented this and derived applicable prism design method on bulk light source. The intensity distribution and efficiency that came out by each design results were compared and analyzed, we got improved results through supplemented design method.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.10 no.1
• /
• pp.16-22
• /
• 2007

This study was carried out to investigate the effects of shading conditions for appropriate light level for several floricultural plants native to Korea. The results under the different shading levels of 0, 30, 50, 60% and full sun light are as follows; Growth of Miscanthus sinensis and Pennisetum alopecuroides, which are heliophyte plants, were better under 30% shading condition than full sunlight. Higher shading levels was poor than control. Growth of Sedum spectable was decreased when light intensity was decreased. As shading level increased, growth reduction rate in Sedum spectable were higher than that of other species. Growth and ornamental value of Arisaema amurense, which is sciophyte plants, were increased under 50% shading.

• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.235-236
• /
• 2015

Microlensing can be seen as a version of strong gravitation lensing where the separation angle of the image formed by light deflection by a massive object is too small to be seen by a ground based optical telescope. As a result, what can be observed is the change in light intensity as function of time; the light curve. Conventionally, the intensity of the source is expressed in magnitudes, which uses a logarithmic function of the apparent flux, known as the Pogson formulae. In this work, we compare the magnitudes from the Pogson formulae with magnitudes from the Asinh formulae (Lupton et al. 1999). We found for small fluxes, Asinh magnitudes give smaller deviations, about 0.01 magnitudes smalller than Pogson magnitudes. This result is expected to give significant improvement in detection level of microlensing light curves.

• Journal of Plant Biology
• /
• v.37 no.3
• /
• pp.285-292
• /
• 1994

Ultrastructural changes in Panax ginseng C. A. Meyer mesophyll chloroplasts and variation of thylakoid membrane protein in responce to the light intensity were studied in leaves of two-y-old plants exposed to two different light intensities under field coditions. The leaves were allowed to function for three months after emergence under two contrasting light conditions. The ginseng chloroplasts of 5% light were filled with highly stacked grana of condensely arrayed thylakoids, so that the stroma space was hardly observed. In contrast, chloroplasts from leaves at 100% sunlight had fewer thylakoid membranes and smaller grana stacks. The number of osmiophilic globules increased. Total Chl content and Chl b content were lower at 100% sunlight than 5% sunlight. The thylakoid membrane proteins in the leaves grown at 100% sunlight showed lower CPIa, LHCII and CP29 than those with 5% sunlight. This effect was most obvious for LHCII. Polypeptides showed major bands at 90, 64, 29-30, 22 and 14 kD, and minor bands at 59, 58, 54, 52, 49, 46, 44, 35, 23, 21 and 18-19 kD. All these bands were lower in intensity in the leaves exposed to 100% sunlight. Moreover, the bands at 58-59, 46-47 and 23 kD disappeared.

• ETRI Journal
• /
• v.27 no.4
• /
• pp.377-384
• /
• 2005

We investigate near-infrared light (NIR) propagation in a model of an adult head using an extensive Monte Carlo (MC) simulation. The adult head model is a four-layered slab which consists of a surface layer, a cerebrospinal fluid layer, a gray-matter layer, and a white-matter layer. We study the effects of a refractive index mismatch on the model, calculating the intensity of detected light, mean flight time, and partial mean flight time of each layer for various refractive indices of the cerebrospinal fluid layer as functions of source-detector spacing. The Monte Carlo simulation shows that the refractive index mismatch presents very rich results including rapidly decaying intensity of detected light and a peak and cross-over in the partial mean flight time with source-detector spacing. We also investigate spatial sensitivity profiles at various source-detector spacings, discussing the index mismatch effect on the model.

• Journal of Life Science
• /
• v.6 no.3
• /
• pp.193-197
• /
• 1996

The action spectrum for mycelial growth and fruitbody primordium formation in Pleurotus ostreatus has been studied by irradiation at various wavelengths. Effective wavelengths. Effective wavelengths were distributed from near ultraviolet to blue region of spectrum. The most effect of light was observed in the region between 340 to 500 nanometers. The light intensity required to obtain of the maximum effect at the most effective wavelengths(430-500nm), was over 6.8 mW/Cm$^{2}$. Up to 6.8 mW/Cm$^{2}$, the primordium formed about 25 hr after the start of illumination. The higher the light intensity, the earlier the formation of the primordium formation : Up to about 6.8 mW/Cm$^{2}$.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.1746-1749
• /
• 1997

A distributed optical fiber temperature sensor can continually monitor the measurand at every point along of its fiber length. It is based on OTDR technics which used extreamlly weak backward scattered light called Raman scattering. When the Pulsed high intensity laser light injected into the optical fiber there are several kind of backscattered light such as Rayleigh, Stokes, and anti-Stokes, etc. caused by impurities molecular vibrations. The temperature distribution is derived form the intensity ratio Raman scatted light-Stokes versus anti-Stokes-and the time function between light injection and signal detection. It is shown that the priniciple of distributed sensing, the system desing, and the result of experiments.

• Journal of Ginseng Research
• /
• v.20 no.3
• /
• pp.318-324
• /
• 1996

The effects of light on the growth and ginsenosides production were examined in the hairy roots of Panax ginsen C.A. Meyer induced by Agrobacterium rhizogines A4. The 9rowth of ginseng hairy roots in 1/2MS liquid medium was significantly decreased with an increment of light intensity (1,000~7,000 lux). The growth of hairy roots under 7,000 lux condition was decreased at 17% compared to the dark condition. The production of 7 ginsenosides in hairy root was very high in 3,500 lux condition. The production of ginsenoside-Rg, and Rf increased 3.3 and, 2.4 times respectively as compared to dark condition. The growth of hairy roots was inhibited by blue light, while ginsenosides production was increased. The sucrose demands of hairy roots was examined in light condition(3,500 lux). The growth of hairy roots in 1/2MS liquid medium with various sucrose concentrations(1~4%) was high in IVp sucrose, while ginsenosides production was high in 3% sucrose condition. The growth and ginsenosides production were high when hairy roots were cultured in dark condition for 1 week and then transferred to light condition(3,500 lux) for 4 weeks. It is suggested that ginsenosides production could be accelerated by light intensity of specific wavelength in cultures of ginseng hairy roots.