• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1669-1670
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• 2006

LED have many problem as narrow light view angle, high price, drift phenomenon of color coordinate, high heating problem for lower power, lower weight and small size. But, with the development of blue LEDs and the improvement of LED brightness, color variation are becoming more and more popular as lighting and application devices in this page, 1 used the Light Tools which was a simulation program in order to recognize optical a few characteristic of LEDs arrangement along reflector matrial and designed LED Arranged 5 phi LED in 5mm interval In the square that was $10{\times}10$ And designs a reflection board on pcb, structural design of PCB changed as five type. - Aluminum, Gold. Chromium, Nickel, Copper.

• Restorative Dentistry and Endodontics
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• v.47 no.1
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• pp.7.1-7.14
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• 2022

Objectives: This study evaluated the bleaching efficacy of different in-office protocols associated with violet light emitting diode (V-LED), and measured the pulpal temperature rise caused by V-LED with or without gel application. Materials and Methods: Bovine incisors were distributed in 4 groups (n = 10): VL - V-LED; HP - 35% hydrogen peroxide (control); HYB - hybrid protocol, V-LED applied without gel for 10 irradiation cycles followed by V-LED applied with gel for another 10 irradiation cycles; and HPVL - gel and V-LED applied for 20 irradiation cycles. Three bleaching sessions were performed with 7-day intervals. Bleaching efficacy was evaluated with ΔE_ab^*, ΔE₀₀ and ΔWI_D. Data were recorded at baseline, 7, 14, 21 and 70 days. For pulpal temperature rise, thermocouples were placed inside the pulp chamber of human incisors. To determine intrapulpal temperature, the teeth were irradiated with V-LED with or without application of bleaching gel. Color difference data were analyzed by 2-way repeated measures ANOVA and Tukey's test. Pulpal temperature was analyzed by t-test (α = 5%). Results: VL exhibited lower color (ΔE_ab^* and ΔE₀₀) and whiteness changes (ΔWI_D) than the other groups. HPVL presented higher color change values than HYB. HYB and HPVL showed not different ΔWI_D values; and HP showed the highest whiteness changes at all times. There were significant differences comparing ΔT with gel (8.9℃) and without gel application (7.2℃). Conclusions: HPLV was more efficient than HYB. The 2 protocols with VL showed similar results to control. Gel application combined with VL promoted higher pulpal temperature than to the no gel group.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.769-772
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• 2008

For several years, many researchers have proposed LED backlight dimming technology for low power consumption and high contrast ratio. One of the major issues plaguing RGB LED with 2D dimming technology is color shift. This undesirable variation makes it difficult to use RGB LED as light sources in the backlight system. This paper describes the useful method of the optical feedback system for 2D dimming RGB LED backlight. The test results show that our proposed method is very suitable for the 2D dimming technology.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.5
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• pp.77-85
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• 2010

In this paper, A new integrated energy simulation results of LED lamp are presented to use it effectively in the office buildings. Generally LED lamp has many advantages in comparison with a general lamp such as long life and no pollution problem like the mercury. It also is excellent in color rendering and small consumption electric power. However LED lamp has some disadvantages to compare to general fluorescent lamp. It is small light flux about 50[%] and narrow light distribution than fluorescent lamp. Therefore, to apply LED lamp in an office building, the illuminance distribution with an environment analysis and cooling, heating and light energy has to be analyzed. The purpose of this study is to analyze light environment, light, cooling and heating energy simulation in office building.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.219-226
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• 2021

LED-to-LED VLC is a technology that uses LEDs as both a transmitter and a receiver unlike the typical VLCs. In this paper, we experimentally demonstrate a micro LED-to-LED VLC using Micro LED. We tested all the possible VLC cases using red, yellow, green, blue, and white color LED as both a transmitter and a receiver, and measured rise time and SNR. Then we calculated channel capacity depending on the LED color sets. Our experimental results show that the best channel capacity is 125 kbps when the transmitter micro LED was blue and the receiver LED was green. We also measured BERs of VLCs using OFDM signal, and we showed a successful micro LED-to-LED VLC upto 250 kbps.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.5
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• pp.494-499
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• 2023

In this paper, in order to apply the CF (color filter) type of the micro light emitting device (Micro LED) display method, a study on the manufacturing process of red and green phosphor inks for the inkjet process was conducted. The blue light-emitting KSF and LuAG phosphors were respectively used to control the phosphor particle size to about 1㎛, and a phosphor ink was prepared by synthesizing with a low-viscosity solution (IPA/Eg). A chemical dispersion method was applied to selectively control the dispersion characteristics in the manufacture of phosphor inks, and in particular, phosphor inks with a dispersant applied a dispersant secured stable dispersion characteristic compared to phosphor inks without a dispersion process. Therefore, it seems possible to manufacture CF for Micro LED through an inkjet process capable of controlling the dispersion characteristics of phosphor ink.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.2
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• pp.10-18
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• 2011

In order to develop highly-integrated RGBY(Red, Green, Blue, Yellow) LED light, a high thermal radiation ceramic package was manufactured, and the encapsulation process was applied with a vacuum printing encapsulation system(VPES). After the completion of vacuum printing, the shape of the encapsulation layer could be controlled by heat treatment during the curing process, and the optical power became highly increased as the encapsulation layer approached a dome shape. The optical characteristics involved in a Correlated Color Temperature(CCT), a Color Rendering Index (CRI), and the efficiency of RGBY LED light were able to be identified by the experimental designing method. Regarding the characteristics of the white light of RGBY LED light, which were measured on the basis of the aforementioned optical characteristics, CRI posted 88, CCT recorded 5,720[$^{\circ}K$], and efficiency exhibited 52[lm/W]. The chip temperature of RGBY LEDs was below 55[$^{\circ}C$] when the consumption power of LED chips was 0.1[W] for the red, 0.3[W] for the green, 0.08[W] for the blue, and 0.24[W] for the yellow. Also, the thermal resistance of the highly-integrated RGBY LED light measured by T3Ster was 2.3[K/W].

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.3-6
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• 2008

The purpose of this study is to investigate the luminous environment of fluorescent lamp and LED lamp in a office space for various color temperature by subject response test. For this, three different color temperatures were tested for the same illuminance level. Based on such test results for various color temperatures of fluorescent lamp and white LEDs, this study is to analyze the preferences of color temperature and light source, and perceptional brightness of each light source and color temperature. Then, this study is to derive the guidelines for the performance of color temperature which are suitable on the purpose and the mood of a office space.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.348-350
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• 2006

Currently the indication method of the traffic signal light which is established in our country displays each "red, yellow, green" using the brightness LED signal light. In this paper, one LED circular arrangement replaces the Current indication method of the traffic signal light using two color LED. Also the blinking signal function of present time uses the MCU of AVR series and it is embodied with magnification and abridgment of the circular arrangement for recognizing easily far away. The signal light indication method which is proposed will be able to substitute the signal light of 3 colors with 1 signal light with economic profit presented the reform measure of energy efficiency improvement together.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.466-471
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• 2009

Generally LED lamp has many advantages to compare with a general lamp, long life and no pollution matter like the mercury. Also it is excellence for color rendering and need to small consumption electric rower. However LED lamp has some disadvantages to compare to general fluorescent lamp and That is small light flux about 50% and narrow light distribution than fluorescent lamp. Therefore, to apply LED lamp in an office building, after analyze a illuminance distribution with an environment analysis and cooling, heating and light energy. The purpose of this study is to analyze light environment. light, cooling and heating energy simulation in Office building.