• Journal of Broadcast Engineering
• /
• v.21 no.4
• /
• pp.538-551
• /
• 2016

At the on-site of broadcasting production, the light source of tungsten halogen has been used as a primary light source for representing video images. Although tungsten halogen light has drawn attention in terms of the color reproducibility which is more similar to the sun light than that of other light sources, meanwhile it had problems in energy efficiency. Recently, the LED light source with high efficiency and long lifetime of the energy source has started getting attention as a substitute light source at the broadcast field. Because of the unique light emission principles, compared with tungsten halogen, LED light source has different characteristics in the quality of the light projected from the light source and color reproduction of the video image through a camera. These characteristics cause the delayed introduction of the LED as the broadcast light source. In this study we measured the quality characteristics of the flatness of the color reproduction and light of the LED light source and will present the experimental data whether it is suitable as the broadcasting light source compared to a reference light source of tungsten halogen. In addition, we suggested the future challenges and standards which are needed to expand usage of LED as a broadcast light source.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.23 no.1
• /
• pp.18-26
• /
• 2009

Recently, from an environmental conservative point of view, the need of high-efficiency lighting system, using LED(Light Emitting Diode) light sources have been increased. However, applied LED light sources without regard to its color and pattern provide visual discomfort to occupant. The objective of this study is not only to evaluate the performance of task work under different correlated color temperature condition, but also furnish the preliminary data as concerning its purpose and user of inner space. For the purpose of this study, two types of LED light sources and a fluorescent light source were selected. Thirty undergraduate students served as the participants. Two different task work sheets were conducted to evaluate the accuracy and duration of time. Results from subjective performance, task work of error modification showed that LED light sources were 2.5[%] higher in accuracy with 17.1[%] lower duration than a fluorescent light source. In the case of reading task work, It is presented 20.6[%] decrease with the LED light sources comparison with a fluorescent light source.

• Korean Journal of Medicinal Crop Science
• /
• v.28 no.3
• /
• pp.200-208
• /
• 2020

Background: Salvia miltiorrhiza Bunge has been used in traditional medicine. The type of light source has an effect on the growth properties and composition of functional compounds in plants. In this study, we analyzed the effects of different artificial light sources on the growth characteristics as well as antioxidant and antimicrobial activities of S. miltiorrhiza. Methods and Results: Seedlings of S. miltiorrhiza were grown under various artificial light sources, including fluorescent light (FL), light emitting diode (LED), and microwave electrodeless light (MEL), for 8 weeks. Growth characteristics were the best in plants treated with MEL. DPPH scavenging activity of the shoot was more pronounced with the FL treatments, while the roots were more active in plants grown under single wavelength lights (i.e., blue and red LEDs). Among the different light source treatments, the blue LED resulted in a higher total phenolic content in the plants. Furthermore, growing plants growth under the red LED enhanced their total flavonoid content. Notably, the antimicrobial properties of plants varied significantly between light source treatments in this study. Except for E. coli, all the tested microorganisms were susceptible to the plant extracts. Conclusions: The type of light source may be an important parameter for the enhancement of plant growth and functional compounds in S. miltiorrhiza.

• Korean Journal of Agricultural Science
• /
• v.44 no.2
• /
• pp.261-271
• /
• 2017

The aim of this study was to investigate the amount of glucosinolates (GSLs) in kale sprouts (Brassica oleracea L. var. acephala) ('TBC') according to different concentrations of sulfur ions in sprout's nutrient solutions (0.0, 0.5, 1.0, and 2.0 mM) and to different light sources [Fluorescent lamp, Red, Blue, and Mix (R+B) LED]. Kale sprouts were cultivated in a growth chamber for 13 days in sulfur solutions. Kale sprouts were treated with fluorescent lamp and LED light sources for 5 days, from eight days after sowing to harvest. Amount of seven types of GSLs (progoitrin, sinigrin, 4-hydroxyglucobrassicin, glucobrassicin, 4-methoxyglucobrassicin, gluconasturtiin, and neoglucobrassicin) were measured in kale sprouts after harvest. The total GSL content was influenced by different sulfur solution concentration, and it was the highest at S 0.5 mM ($172.54{\mu}mol{\cdot}g^{-1}DW$) and the lowest at S 2.0 mM ($163.09{\mu}mol{\cdot}g^{-1}DW$). The GSL content was influenced by different light source, and it was the highest with Red LED ($159.23{\mu}mol{\cdot}g^{-1}DW$) and the lowest with Blue LED ($147.57{\mu}mol{\cdot}g^{-1}DW$). As the sulfur solution concentration increased under all light source, progoitrin and sinigrin contents tended to decrease while glucobrassicin content showed an upward tendency for all of the light sources. The content of glucobrassicin was higher than that of progitrin when treated with sulfur solutions for all LED light sources. Sinigrin, which has excellent anti-cancer effects, showed the highest rate (92.2%) among all the GSLs, under all of the light sources.

• The Journal of Korean Academy of Prosthodontics
• /
• v.16 no.1
• /
• pp.38-44
• /
• 1978

Color is an important factor in dental esthetics. Application of natural tooth color will not fail to produce pleasing results. But a standardized method of shade matching has not been adopted. If we are to overcome the color matching problem in dentistry, an understanding of the nature of color and light is essential. The purpose of this study was to compare the effects of different light sources and different background colors on the ability of observers to correctly match shades of artifical teeth. And observation was made to determine if the time spent in making a shade match was a factor in the correctness of the response. A test method was devised and 50 individuals made observations which were recorded and analyzed. $X^2$-test gave results indicating that the time factor had no effect on the response made. An analysis of variance showed the following effects significant at the five percent level; (1) light source (2) background color (3) subject. The following conclusions can be drawn from this study; (1) The time spent in making shade selection is not a factor in the correctness of the selections. (2) The light source used is an important factor in matching tooth shade; and there is no significant difference between the light sources in shade matching. (3) Under the conditions of this study, the greatest accuracy in shade matching was obtained on the brown background.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.1057-1060
• /
• 2004

In this study, the wear characteristics of five different dental composite resins cured by conventional halogen light and LED light sources were investigated. Five different dental composite resins of Surefil, Z100, Dyract AP, Fuji II LC and Compoglass were worn against a zirconia ceramic ball using a pin-on-disk type wear tester with 15 N contact force in a reciprocal sliding motion with sliding distance of 10 mm/cycle at 1Hz under the room temperature dry condition. The wear variations of dental composite resins were linearly increased as the number of cycles increased. It was observed that the wear resistances of these specimens were in the order of Dyract AP ＆gt; Surefil ＆gt; Compoglass ＆gt; Z100 ＆gt; Fuji II LC. On the morphological observations by SEM, the large crack formation on the sliding track of Fuji II LC specimen was the greatest among all resin composites. Dyract AP showed the least wear with few surface damage. There is no significant difference in wear performance between conventional halogen light curing and light emitting diodes curing sources. It indicates that a light emitting diodes (LED) source can replace a halogen light source as a curing unit for composite resin restorations.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.42 no.6
• /
• pp.711-720
• /
• 2009

Characteristics of spectral irradiance based on the distance from the light source, which combined metal halide lamp and high-luminance light-emitting diode (LED) light, were studied to investigate a suitable operating method for fishing lamps of the next generation. A 380-780 nm wavelength radiation was superior when using 1 W electrical power in the order of metal halide lamp, blue LED, white LED, and combined LED lights. The wavelengths at which the irradiance was at a maximum were fixed to 581 nm for the light source, which was combined for each ratio. If the irradiance characteristics at 300-1100 nm wavelengths were set as 100%, the irradiance rates at 400-599 nm were 100%, 72.7%, 88.9%, and 69.5% for the blue, white, combined LED lights, and metal halide lamp, respectively. This indicated that the color rendering of the LED lights was dependent on the metal halide lamp light source. When the horizontal profiles (450-550 nm wavelength) of irradiances were compared to a different type of light source in the ratio white LED: combined LED lights: blue LED: metal halide lamp, the irradiated area of more than $0.01\;{\mu}mol/s/m^2/nm$ was in the ratio 1.0 : 1.3 : 1.7 : 37.3, respectively. Based on the radiation characteristics and irradiance according to the distance from the light source, LED lights have an estimated economic efficiency if used before and after operation of a metal halide lamp.

• The Korean Fashion and Textile Research Journal
• /
• v.8 no.6
• /
• pp.721-726
• /
• 2006

In this article I visually assessed the relation between luminous source and color, and analyzed subjective recognition of color by light source and image of color, aiming at giving guidelines in selecting source of light suitable for each purpose, thereby contributing to enhanced quality of life. For this purpose, I subjectized, by applying a quantitative method, the objective measurement that employs sensory evaluation method for 14 categories of color, light and feelings in visual perception of textile colors (blue, green and yellow) by color of light source (color temperature of 2800K, 4200K and 6500K), Followings are the conclusions derived form this study. Colors of textile were differently perceived according to the color of light source. When examining common recognition of textiles in blue, green and yellow, 2800K was said to give dirty, soft and blurred image, as for 4200K clear, wide and fine feelings were said, and pure, vivid, refined and bright image were marked for 6500K. As for 2800K, it got the most low appraisals compared with others. In conclusion, image and feeling of the same colors can differ according to light source, which indicates the importance of appropriate selection of light source for purpose of use. As for yellow, the number of assessment result that shows significant difference was the smallest among the three colors. So, it can be concluded that when we consider the recognition of color in mixing different colors, mixing with yellow can result in difficulty in visually perceiving difference of colors. Therefore, it is regarded that more considerable attention is required when dealing with yellow color.

• Restorative Dentistry and Endodontics
• /
• v.27 no.6
• /
• pp.561-568
• /
• 2002

Purpose of this research is estimating polymerization depth of different source of light. XL 3000 for halo-gen light, Apollo 95E for plasma arc light and Easy cure for LED light source were used in this study. Different shade (B1 & A3) resin composites (Esthet-X, Dentsply, U.S.A.) were used to measure depth of cure. 1, 2, and 3 mm thick samples were light cured for three seconds, six seconds or 10 seconds with Apollo 95E and they were light cured with XL-3000 and Easy cure for 10 seconds, 20 seconds, or 40 seconds. Vicker's hardness test carried out after store samples for 24 hours in distilled water. Results were as following. 1. Curing time increases from al1 source of lights, oui$.$ing depth increased(p<0.05). 2. Depth (that except 1mm group and 2mm group which lighten to halogen source of light) deepens in all groups, Vickers hardness decreased(p<0.05). 3. Vicker's hardness of A3 shade composite was lower in all depths more than B1 shade composites in group that do polymerization for 10 seconds and 20 seconds using halogen source of light(p<0.05), but group that do polymerization lot 40 seconds did not show difference(p>0.05). 4. Groups that do polymerization using Plasma arc and LED source of light did not show Vicker's hardness difference according to color at surface and 1mm depth(p>0.05), but showed difference according to color at 2mm and 3mm depth(p<0.05). The results showed that Apollo 95E need more polymerization times than manufacturer's recommendation (3 seconds), and Easy cure need polymerization time of XL-3000 at least.

• Journal of Sensor Science and Technology
• /
• v.27 no.5
• /
• pp.335-339
• /
• 2018

The optical characteristics of a terahertz (THz) antenna-coupled bolometer (ACB) detector were evaluated using a pulsed quantum cascade laser (QCL) and radiation blackbody sources. We investigated a method for measuring the responsivity and noise-equivalent power (NEP) of the THz detector using two different types of light sources. When using a QCL source with a frequency of 3 THz, the average responsivity of 24 devices was $1.44{\times}10^3V/W$ and the average NEP of those devices was $3.33{\times}10^{-9}W/{\surd}Hz$. The average responsivity and NEP as measured by blackbody source were $1.79{\times}10^5V/W$ and $6.51{\times}10^{-11}W/{\surd}Hz$, respectively, with the measured values varying depending on the light source. This was because the output power of each light source was different, with the laser source being driven by a pulse type wave and the blackbody source being driven by a continuous wave. The power input to the THz sensor was also different. Futhermore, the responsivity and NEP values measured using band pass filter (BPF) were similar to those measured when using only THz windows. It was found that ACB sensor responds normally in the THz region to both the laser and the blackbody source, and the method was confirmed to effectively evaluate the characteristics of the THz sensor.