• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.11
• /
• pp.7256-7261
• /
• 2015

This paper devised a plant growing system As LED light source, three monochromatic lights (red, blue, white) and three mixed lights (red1+blue1, red2+blue1, red1+blue2) were made. According to the optical properties of those LED light sources and change in the amount of light, this author analyzed the characteristics of luminance and PPFD and also plant growth. According to the light efficiency of those LED light sources, it was high in white light as 125 lm/W and was low in red1+blue2 light as 9.9 lm/W. This result shows that monochromatic light has higher light efficiency than mixed light. The PPFD ($25{\mu}mol$, $50{\mu}mol$, $100{\mu}mol$) luminance in different wavelengths of LEDs was high in white LEDs and was low in blue LEDs. therefore, it is possible to devise an efficient LED lighting system appropriate for growing plants by variety monochromatic lights and mixed light wave length combination of LED light source.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.20 no.1
• /
• pp.49-61
• /
• 2008

This study investigates the characteristics of stem waves along a vertical wall generated by obliquely incident random waves through laboratory experiments conducted in a wave basin and numerical simulations using REF/DIF S model developed by Kirby and $\ddot{O}zkan$(1994). The investigation is focused on the effect of random waves on the propagation characteristics of stem waves and the difference or similarity between monochromatic and random waves. The results of REF/DIF S model are compared with laboratory measurements and good agreements are obtained. The relative significant wave height along a wall is almost same with monochromatic condition, but the wave pattern along normal to the wall shows a significant difference.

• Animal Bioscience
• /
• v.34 no.5
• /
• pp.931-940
• /
• 2021

Objective: Light is a significant component of housing environment in commercial poultry industry. This study was conducted to investigate whether Pekin ducks perform better under monochromatic lights than under white light with respect to their growth performance, carcass quality, eyeball development, oxidation resistance, and cecal bacterial communities. Methods: A total of 320 one-day-old male Pekin ducklings were randomly distributed into five rooms with different light treatments, white, red, yellow, green, and blue light. Each room consisted of 4 replicated pens with 16 ducklings per pen. Results: Blue light significantly decreased fat deposition by decreasing abdominal fat. Long wavelength light, such as red, green, and yellow light, considerably increased the back-to-front eyeball diameter and the red light potentially enlarged the side-to-side eyeball diameter. Besides, the blue light had adverse effects on the oxidation resistance status in terms of increasing the product malonaldehyde of lipid oxidation and decreasing the plasma concentration of total superoxide dismutase. The phyla of Firmicutes had the greatest abundance in the green and blue treatments, while Bacteroidetes in blue treatment was the least. The genus of Faecalibacterium was significantly lower under the red light. Conclusion: The high risk of cecal health status and decreased anti-oxidation activity were observed under blue light. Red, yellow, and green light might increase the risk of oversized eyeball and cecal illness. Therefore, monochromatic lights compared to white light did not show advantages on the performance of housing ducks, it turns out that the white light is the best light condition for grow-out ducks.

• Journal of the Korean Ceramic Society
• /
• v.56 no.1
• /
• pp.71-76
• /
• 2019

Monochromatic amber phosphor in glasses (PiGs) for automotive LED applications were fabricated with $YAG:Ce^{3+}$, $CaAlSiN_3:Eu^{2+}$ phosphors and Pb-free silicate glass. After synthesis and thickness-thinning process, PiGs were mounted on high-power blue LED to make monochromatic amber LEDs. PiGs were simple mixtures of 566 nm yellow YAG, 615 nm red $CaAlSiN_3:Eu^{2+}$ phosphor and transparent glass frit. The powders were uniaxially pressed and treated again through CIP (cold isostatic pressing) at 200 MPa for 20 min to increase packing density. After conventional thermal treatment at $550^{\circ}C$ for 30 min, PiGs were applied by using GPS (gas pressure sintering) to obtain a fully dense PiG plate. As the phosphor content increased, the density of the sintered body decreased and PiGs containing 30 wt% phosphor had full sintered density. Changes in photoluminescence spectra and color coordination were investigated by varying the ratio of $YAG/CaAlSiN_3$ and the thickness of the plates. Considering the optical spectrum and color coordinates, PiG plates with $240{\mu}m$ thickness showed a color purity of 98% and a wavelength of about 605 nm. Plates exhibit suitable optical characteristics as amber light-converting material for automotive LED applications.

• Journal of the Korean Society of Radiology
• /
• v.16 no.5
• /
• pp.553-558
• /
• 2022

The purpose of this work was a simulation study to evaluate the virtual monochromatic (VM) image quality of blood vessels compared to the monochromatic image. Dual-energy images were obtained based on the linear attenuation coefficients of five materials at 50 keV and 80 keV at low- and high-energies, respectively. A weighting factor is required to synthesize the VM image, and the liver and bone were used as basis materials to obtain the weighting factor. VM images were synthesized at energies ranging from 30 keV to 100 keV. Image quality was evaluated by Contrast to noise ratio (CNR) and noise by setting calcium and contrast medium as signals and blood as background. According to the results, the energies with the maximum CNR were 50 keV and 60 keV for calcium and contrast medium, respectively. The energies showing the minimum noise were 70 keV, 70 keV, and 60 keV in calcium, iodine contrast medium, and blood, respectively. The VM image can contribute to the improvement of diagnostic performance in CT examination because it can implement an image at the optimal energy that minimize noise and maximize CNR.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2012.05a
• /
• pp.845-846
• /
• 2012

• Journal of Korean Society of Forest Science
• /
• v.99 no.5
• /
• pp.750-754
• /
• 2010

Among the environmental conditions employed in micropropagation, light quality plays an important role in growth, specially morphogenesis and photosynthesis. The effect of radiation quality (350-740 nm) on the development and growth of zygotic embryos and in vitro plantlets of open-pollinated chestnut (Castanea crenata S. et Z.) were studied. Two types of explants were exposed for 4 weeks to cool white (W, as control), monochromatic red (R, peak emission 650 nm), monochromatic blue (B, peak emission 440 nm), red+blue (R+B, 1:1), or red+far-red (R+Fr, 1:1, far-red peak emission 720 nm) radiation from a light-emitting-diode (LED) system. While the zygotic embryos showed positive photoblastic behavior, their germination was inhibited by blue radiation. Hypocotyl elongation and root development were promoted by red radiation. The emergence of primary leaf and its expansion were faster under blue than under red radiation. In the plantlets, red and red+far-red radiation significantly increased the formation and growth of the root, whereas blue light reduced rooting. Therefore, radiation quality appears to influence some steps in the development of zygotic embryos and plantlets in the chestnut.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.13 no.3
• /
• pp.189-194
• /
• 2001

The present study describes the Bragg reflection of monochromatic water waves propagating over a train of doubly-sinusoidally varying topographies. A numerical model based on the boundary element method is firstly verified by calculating reflection and transmission coefficients of waves over a trench. Calculated solutions are compared with those of the eigenfunction expansion method. The model is then used to simulated reflection of monochromatic water waves propagating over doubly-sinusoidally varying bottom topographies. Obtained reflection coefficients are compared with those of available laboratory measurements, those of the eigenfunction expansion method and the extended mild-slope equation. A reasonable agreement is shown.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.19 no.6
• /
• pp.586-595
• /
• 2007

The analytic solution of wave scattering of monochromatic waves on a pile breakwater by an eigenfunction expansion method is extended to the case of directional irregular waves. The scattering wave spectrum and the force spectrum can be expressed from the reflection coefficient, transmission coefficient and the wave forces obtained from changing frequencies and incident angles in monochromatic waves. By numerical integration of 2-dimensional spectrum which is function of frequencies and incident angles, the representative values for the scattered waves and wave forces are obtained and the dependence of the transmission coefficients and wave forces on the directional distribution function, the principal wave direction, the submergence depth, and porosity is analyzed.

• Korean Journal of Optics and Photonics
• /
• v.20 no.6
• /
• pp.375-380
• /
• 2009

The scattering of a normally incident monochromatic light by optically active concentric double cylinders is studied by using a numerical method. A numerical code is developed on the basis of the analytical solutions, and the angular distributions of the intensity and the polarization of the scattered light are computed for some specific cases. The numerical code can be used to non-invasively determine the size, structure, and composition of a double cylinder with high accuracy by measuring the angular distribution of the scattered light by an experiment.