• Proceedings of the KIEE Conference
• /
• 1998.07e
• /
• pp.1770-1772
• /
• 1998

This study is concluded under by investigation about the lighting environment on a blackboard in elementary, middle, high school of inchon metropolitan. 1. The illumination was approximated to standard value in the side of quantity by the result of the Mimistry of Education's command. However, the uniformity of illuminescence was relatively increased. 2. In order to raise the blackboard lighting, we installed local lighting fixture for blackboard but most of schools are directly adopted to the way of sticking to the blackboard and the lower part of the blackboard is not effective. So that it is desirable of teacher and students to put the local lighting in front of the higher part of the blackboard or install in setting the perfect diffusion light from the ceiling. 3. Deviation of luminance is also more groat when local lighting exist for blackboard. And, regardless of local lighting, luminance of blackboard in side of window, from direction of floor is high because of regular reflected light. Therefore a curtain or blind must be installed pertinently.

• Proceedings of the KIEE Conference
• /
• 2006.07c
• /
• pp.1673-1674
• /
• 2006

The most ideal light source known to the mankind is sunlight. Therefore, whenever an artificial light source is needed in a dark place such as in a shadowed houses, the utmost goal is to find an artificial light characteristics of which approaches that of sunlight. On this ground, we have investigated a Neodymium lamp as a possible substitute for sunlight. Especially, the local and the color rendering, a life expectancy, and the overall efficiency are carefully studied.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2008.04a
• /
• pp.84-89
• /
• 2008

Glass fiber reinforced composite decks have high-strength, light-weight and high durability. The composite decks having vertical snap-fit connections are designed for pedestrian bridges and their structural behavior are studied. Especially in this paper, local behavior of the developed composite deck for pedestrian bridge is verified by both analysis and experiment.

• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.1
• /
• pp.40.3-40.3
• /
• 2019

There is growing evidence for the dependence of Type Ia supernova (SN Ia) luminosities on the environments. The origin of this correlation, however, is under debate. In order to explore the physical origin of the trend in detail, we analyze SN Ia light-curves by combining a sample of 1231 SNe Ia over a wide redshift range (0.01 < z < 1.37) in various SN surveys and employing two independent light-curve fitters of SALT2 and MLCS2k2. Although SALT2 is the most widely used fitter in the SN community, MLCS2k2 has a novelty in the context of an investigation of the luminosity evolution of SNe Ia. For this reason we use both fitters and analyze them separately. We also determine a stellar mass and a star formation rate (SFR) for a sample of ~600 host galaxies. In addition, because recent low-redshift studies suggest that this dependence manifests itself most strongly when using the local SFR at the SN location, we introduce a new method to infer the local environments by restricting the SN Ia sample in globally star-forming host galaxies to a low-mass host galaxy subset (${\leq}10^{10}M_{\odot}$). We find that SNe Ia in low-mass and star-forming host galaxies are fainter than those in high-mass and passive hosts, after light-curve corrections. Especially, for the first time in host studies, we show that SNe Ia in locally star-forming environments are $0.081{\pm}0.018$ mag fainter ($4.5{\sigma}$) than those in locally passive environments from the sample including SNe at the high-redshift range. Considering the significant difference in the mean stellar population age between these environments, the result would suggest that the origin of the environmental dependence is the luminosity evolution of SNe Ia.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.28 no.12
• /
• pp.1-5
• /
• 2014

Since the "Light Pollution Prevention Act" was executed, the installation of the light cutoff panel to the security lightings which caused light trespass has been increased in the local government. The light cutoff panel is effective in reducing the light trespass in term of the cost-benefit. Because the installation of the light cutoff panel is inexpensive than the change of the security lighting. But the reflected light from the surface of the light cutoff panel has been regarded as another light pollution problem to solve. Therefore, we try to improve light cutoff panel by changing the light reflectivity characteristic of the surface of the light cutoff panel. First, we laminated the surface of light cutoff panel by black powder to reduce the light reflectivity of the light cutoff panel. After the black powder lamination, the light reflectivity on the light cutoff panel improved from 85% to 5%. And we compared reflected light caused by black powder laminated light cutoff panel with the one of no surface treatment cutoff panel. The vertical illuminance was measured at 3, 6, 9m in front of the security lighting and 3, 6, 9, 12, 15, 18m in back of the security lighting to evaluate the reflected light. And the measurement height was determined of 1.5m considering the height of the 1th floor of an apartment house. In this study, we found that the reflected light from the light cutoff panel can be reduced about 90% by the black powder lamination method. The results derived from this study will be helpful to develope the various kind of light cutoff panel which minimize the adverse effect like reflected light of light cutoff panel.

• KIEAE Journal
• /
• v.8 no.6
• /
• pp.21-26
• /
• 2008

According to the tendency of energy efficiency and environment-friendly chracteristics, demend of High-efficiency lighting using LED(Light Emitting Diode)are being increased actively and applied in various fields. However, In order to adequate application of LED light sources, it is necessary to lighting environment and luminous characteristics of LED light sources. This Study aims to characterize the work-plane lighting environment by LED light sources comparing with fluorescent light sources which are widely used. For the sake of this study, a fluorescent light source and 5 LED light sources were introduced and luminance and correlated color temperature were measured to evaluate luminance contrast. The experimental model is Mock-up which is $4.9m{\times}7.2m$ with a height of 2.9m. The test room was set up partition and desks. Luminance and correlated color temperature were measured work-plane on the desk which was set up local lighting by the Radiant Imaging ProMetric 1400. The optical characteristics data of LED can give a lot of advantages to design LED lighting appliances. Hereafter, the object of research will be conducted to evaluate effects of LED light sources on working performance, survey of visual performance, preference and physiology of subjects.

• KIEAE Journal
• /
• v.10 no.1
• /
• pp.65-72
• /
• 2010

The use of natural light has the potential for improving both the energy efficiency and indoor environmental quality in buildings. A light-pipe system can introduce daylight to spaces that would otherwise not be able to benefit from the advantages of daylight penetration. For the light-pipe system to be widely used in Korea, it is important to quantify its daylighting performance with due consideration regarding the effects imposed by the local climate conditions. This paper presents the evaluation results of existing semi-empirical models to predict daylighting performance of a light-pipe system. The evaluation of the existing models was based on the monitoring data obtained from a underground parking lot in which the light-pipe system was installed. Comparisons were made between the predicted and the monitored data obtained from the study. The results indicated that semi-empirical models which was developed using the experimental data obtained under the Korean climatic conditions had a good prediction performance. We also quantified the effects caused by sky conditions, solar altitudes, room dimensions, and the aspect ratio of a light-pipe system on both the daylighting performance of the light-pipe system and the indoor illuminance distributions of the space using the semi-empirical model. Finally, this paper provides the design guideline of the light-pipe system for its application to an underground parking lot space.

• Journal of Institute of Control, Robotics and Systems
• /
• v.14 no.8
• /
• pp.767-773
• /
• 2008

This paper presents a localization system based on the use of electric compass and tracking IR light source. Digital RGB(Red, Green, Blue)signal of digital CMOS Camera is sent to CPLD which converts the color image to binary image at 30 frames per second. CMOS camera has IR filter and UV filter in front of CMOS cell. The filters cut off above 720nm light source. Binary output data of CPLD is sent to DSP that rapidly tracks the IR light source by moving Camera tilt DC motor. At a robot toward north, electric compass signals and IR light source angles which are used for calculating the data of the location system. Because geomagnetic field is linear in local position, this location system is possible. Finally, it is shown that position error is within ${\pm}1.3cm$ in this system.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.1409-1415
• /
• 2010

A linear induction motor have advantages for reducing mechanical frictions and noises because it has thrust force by induced torque instead of friction force between rail and wheels. An it has additional advantage for reducing volume of bogie frame for light rail transit. The small volume causes the cost of construction down. Recently, researches of linear induction motor for thrust force of the light rail transit have been actively studied. For the rail transit, vehicle is running as follow accelerating and constant speed, finally decelerating speed passing local stops between stations. The light rail transit have only these three patterns of operating. Thus, design of that has different design specifications from others. In this paper, the linear induction motor for the light rail transit was designed considering the goal speed, accelerating time, and accelerating distance for approaching the goal speed. The designed motor was proved that it could meet the requirement of accelerating performance by2-dimensional finite element method and mechanical dynamics equation.

• Journal of Dental Anesthesia and Pain Medicine
• /
• v.23 no.4
• /
• pp.229-236
• /
• 2023

Background: Local anesthesia has been reliably used to control pain during dental procedures and is important in pediatric dentistry. However, children occasionally complain of prolonged numbness after dental treatment, leading to several problems. Studies conducted to reverse the effect of local anesthesia using phentolamine mesylate and photobiomodulation therapy (PBM) are encouraging but limited. PBM is a type of light therapy that utilizes visible and near-infrared non-ionizing electromagnetic spectral light sources. Hence, this study used this modality to compare the reversal of local anesthesia at two different wavelengths. This study compared the effect of PBM at 660 and 810 nm wavelengths on the reversal of soft tissue local anesthesia using a diode LASER in pediatric dentistry. Method: Informed consent and assent were obtained, and the participants were then divided randomly into three groups of 20 children each: control group-without LASER irradiation, LASER irradiation at 660 nm, and LASER irradiation at 810 nm. Sixty children aged 4-8 years with deciduous mandibular molars indicated for pulp therapy were administered an inferior alveolar nerve block. After 45 min of injection, a duration that was similar to the approximate duration of treatment, they were exposed to 660- and 810-nm LASER irradiation according to their groups until reversal of local anesthesia was achieved. The control group did not undergo LASER irradiation. The reversal of the soft tissue local anesthetic effect was evaluated using palpation and pin prick tests every 15 min, and the LASER irradiation cycle continued until reversal of the soft tissue local anesthesia was achieved. Results: A significant reduction of 55.5 min (27.6%) in the mean soft tissue local anesthesia reversal time was observed after the application of 810 nm wavelength PBM and 69 min (34.7%) after 660 nm wavelength LASER irradiation. Conclusion: PBM with a 660 nm wavelength was more effective in reducing the mean soft tissue local anesthesia reversal duration, and thus can be used as a reversal agent for soft tissue local anesthesia in pediatric dentistry.