• Journal of Information Display
• /
• v.13 no.4
• /
• pp.159-166
• /
• 2012

In this paper, a display's emotional image quality can be primarily determined by designing the proper luminance level. Though displays with high luminance are preferred, too much light emission from a display may cause glare or visual fatigue to viewers. To find out the proper luminance level based on various video contents, this study was conducted with an OLED display with a real-black level and a wide color gamut, and with an LCD display with a high luminance level, to set the glare threshold under various conditions. The optimum luminance levels according to the display's loading ratio were found, and the maximum luminance that did not cause a glare in the test is proposed.

• Journal of Information Display
• /
• v.2 no.1
• /
• pp.14-19
• /
• 2001

Plasma display panel(PDP) have gained great attention due to their potential application to large-area display including HDTV. The luminance and luminous efficiency of PDP, however, should be improved to realize this goal. In this study, we examined experimentally the effects of phosphor thickness and discharge gap on the luminance and luminous efficiency of ac PDP. For the rib height of 110 ${\mu}m$, whereas the optimum phosphor thickness was about 30 ${\mu}m$. The optimum thickness of green phosphor was about 50 ${\mu}m$ for the rib height of $120{\sim}160\;{\mu}m$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.4
• /
• pp.18-29
• /
• 2015

The purposes of this research and development are as follows: first, to provide pleasant driving environments inside tunnels; second, to improve the current illumination environments lacking in diffusion luminance meters to meet tunnel lighting standards; and, third, to reduce the consumption of tunnel lighting energy accounting for approximately 65% of tunnel maintenance costs because of inadequate visual environments and tunnel operations. Further details are listed below. Firstly, an image luminance meter for tunnels that can implement the L20-method which is a tunnel luminance method that follows the international standards of CIE88, which was developed in order to improve and change the existing illumination-based tunnel lighting operation system to a luminance-based system. (The margin of error of below 5% according to the results of a test by an authorized agency and field test). Secondly, early illumination control is possible since the lighting control system that can be operated based on luminance enables interlocking control of the inside and outside of a tunnel using ethernet communication. Thirdly, guidelines for field application of the system are proposed. In addition, the luminance inducers of tunnels are found and the reflexibility of each facility that may reduce luminance of the boundaries is also proposed. Fourthly, as a result of a test bed, power consumption of luminance-based lighting operations decreased by 15.6% compared to illumination-based operations. Applying the feedback controls and maintenance factors of internal/external luminance meters, it reduced by 36.4%. Therefore, we became able to provide a luminance-based lighting operation system that complies with tunnel lighting design standards and provides a visual environment for drivers.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2000.11a
• /
• pp.135-143
• /
• 2000

This parer is the among educational environment, lighting's role is more important since it improves the visual tasks, capability of work, and it help to build both balanced mind and body. Also, since students need spend most of their time inside rather than outside, students need appropriate illuminance everyday. If optimum illuminance and distribution of luminance is properties controlled, people can decrease the fatigue of eyes, and also, people can maximize their efficiency of work. This present studying class chose of two school measured illuminance using the computer simulation improved ratio of luminance and luminance by distribution of lighting improve the economy and energy saving.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.10a
• /
• pp.613-616
• /
• 2001

The effect of codopants on the electroluminescent properties for SrS-Ce based thin films was studied. The active layer was deposited by electron beam with sulfur The wavelength of eletroluminecence shifted with codopants and their concentrations. The intensity ratio of blue to green were found In the CeP-doped device, but the highest total intensity of luminance showed about 850cd/$m^2$ in the CeCl$_3$+KCL-doped device, which indicates that codopants are playing an important role of luminance. At any device, the luminance was the strongest at 0.2 mol% concentration among the concentration studied, suggesting the existence of optimum concentration. By post-annealing Luminance of most devices was improved, but the shift of wavelength was not observed.

• International Journal of Highway Engineering
• /
• v.17 no.5
• /
• pp.67-73
• /
• 2015

PURPOSES : This study was conducted to derive the optimum mixing ratio of phosphorescent pigment for the development of phosphorescent line marking. METHODS: In this study, we utilized a literature review and case study methodology, to describe the domestic and foreign state of practice for the production and mixing of phosphorescent pigment for use in line marking. The optimal mixing ratio was derived by comparing the reduction in luminance over time for the various phosphorescent pigment mixing ratios identified in the literature. In addition, performance and construction characteristics were analyzed using field testing techniques. RESULTS : The results were as follows: 1) the results of the luminance performance standards tests showed that all of the phosphorescence test specimens satisfied the phosphorescent fire protection standard. As the phosphorescent pigment mixing ratio increased, the luminance value increased, 2) the luminance reduction rate was minimum at the mixing ratio of 50%. However, when compared to a mixing ratio 40%, a small difference was recorded, the luminance reduction rate from the mixing ratio of 40% is judged as being converged. Therefore, in view of the economic efficiency, it was determined that the optimal mixing ratio was 40%, 3) as a result of construction on the field, a mixing ratio of 40% was found to have a higher luminance value than the general line marking for up to three hours after sunset, 4) it was found that the phosphorescent line markings without glass beads spraying had a higher luminance value than the phosphorescent line markings with glass beads spraying. CONCLUSIONS : Through the results of the basic experiments of the line markings obtained by blending a phosphorescent pigment, the results could be applied to play an important role in the development of phosphorescent line marking paint technology and in establishing application planning for on-site construction characteristics.

• Transactions on Electrical and Electronic Materials
• /
• v.13 no.2
• /
• pp.60-63
• /
• 2012

Enhancement of efficiency and luminance of organic light-emitting diodes was investigated by the introduction of a lithium carbonate ($Li_2CO_3$) electron-injection layer. Electron-injection layer is used in organic light-emitting diodes to inject electrons efficiently between a cathode and an organic layer. A device structure of ITO/TPD (40 nm)/$Alq_3$ (60 nm)/$Li_2CO_3$ (x nm)/Al (100 nm) was manufactured by thermal evaporation, where the thickness of $Li_2CO_3$ layer was varied from 0 to 3.3 nm. Current density-luminance-voltage characteristics of the device were measured and analyzed. When the thickness of $Li_2CO_3$ layer is 0.7 nm, the current efficiency and luminance of the device at 8.0 V are improved by a factor of about 18 and 3,000 compared to the ones without the $Li_2CO_3$ layer, respectively. The enhancement of efficiency and luminance of the device with an insertion of $Li_2CO_3$ electron-injection layer is thought to be due to the lowering of an electron barrier height at the interface region between the cathode and the emissive layer. This is judged from an analysis of current density-voltage characteristics with a Fowler-Nordheim tunneling conduction mechanism model. In a study of lifetime of the device that depends on the thickness of $Li_2CO_3$ layer, the optimum thickness of $Li_2CO_3$ layer was obtained to be 1.1 nm. It is thought that an improvement in the lifetime is due to the prevention of moisture and oxygen by $Li_2CO_3$ layer. Thus, from the efficiency and lifetime of the device, we have obtained the optimum thickness of $Li_2CO_3$ layer to be about 1.0 nm.

• Journal of Surface Science and Engineering
• /
• v.40 no.2
• /
• pp.103-106
• /
• 2007

We have investigated the optical and electrical properties of surface mounted white light emitting diode (LED) chips prepared by using yellow phosphors on the blue LED chip. The yellow phosphor mixed with transparent epoxy was coated on the prepared LED chip. The optimum mixing conditions with epoxy and yellow phosphor is obtained at the mixing ratio of epoxy:yellow phosphor = 97:3 wt%. The maximum luminance and light emitting efficiency are above $80,000cd/m^2$ and 23.2 lm/W, respectively, at the bias voltage of 2.9 V. There was no distinct change in the luminance strength with changing of the yellow phosphor ratios. The current of the white LED chip is about 30 mA at 2.9 V.

• Journal of the Korean Institute of Rural Architecture
• /
• v.10 no.3
• /
• pp.27-34
• /
• 2008

Recently, the outdoor lighting of architectural Facade has increased for the improvement of night-scape in urban and coastal resort. The purpose of this research is to analyze lighting characteristics; Luminance, Illuminance, Color Temperature, Chromaticity in Gyengpo Park of Eastern famous coastal resort. The result of this paper is as follows: 1) The Luminance ratio was measured that compare to the 1:10 criterion(IESNA) was in excess to the most building except "K". Because of these condition, Luminance environments was injurious to visual health the overuse of the outdoor lighting or glare to the eyes. 2) The level of vertical Illuminance value was insufficient 33.3% among the cases of survey with 4Lux standard of CIE. 3) The kinds of outdoor lighting of BLDG were increased lighting emitting diode(LED), metal halide(MH) instead of reduction trend of neon, fluorescent light, halogen. As the crisis of Energy resources we will be investigate adapt method of outdoor lighting, which design is based on economical efficiency by the use of optimum lighting.

• Journal of the Optical Society of Korea
• /
• v.18 no.1
• /
• pp.89-94
• /
• 2014

It is established that the perceived image contrast is affected by surround luminance. In order to get the same perceived image contrast, the optimum surround compensation ratios for those surround conditions is needed. Much research has been performed for dark, dim, and average surrounds. In this study, a wide range of surround luminance from dark up to $2087cd/m^2$ was considered. Using magnitude estimation method, the change in perceived brightness of six test stimuli was measured under seven surround conditions; dark, dim, 2 levels of average, bright, and 2 levels of over-bright surrounds. To drive the perceived image contrast from the perceived brightness, two different definitions of contrast were tested. Their calculated results were compared with the visual data of our previous work. And to conclude, the perceived contrast compensation ratios were 1:1.11:1.2 for average, dim and dark surrounds. These were close to CIECAM02 model (1:1.17:1.31). Besides, for average, bright, over-bright1 and over-bright2 surrounds the ratios 1:1.17:1.42:1.69 were determined. For intermediate or more extreme surround conditions, the compensation ratio was obtained from the linear interpolation or extrapolation.