• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.323-324
• /
• 2006

This study proposes an effective algorithm that can simulate a lighting environment, especially an LED backlight unit, using the photon mapping method. For higher reliable simulation, we modeled spectral and optical characteristics of LEDs, light sources, and optical sheets. From rendered images, we confirmed that the proposed algorithm can effectively simulate the lighting distribution of LED backlight unit.

• The Journal of Advanced Prosthodontics
• /
• v.10 no.4
• /
• pp.291-299
• /
• 2018

PURPOSE. To assess the degree of conversion (DC) and light irradiance delivered to light-cured and dual-cured cements by application of different light sources through various types of monolithic computer-aided design and computer-aided manufacturing (CAD/CAM) materials. MATERIALS AND METHODS. RelyX Ultimate Clicker light-cured and dual-cured resin cement specimens with 1.5-mm thicknesses (n=300, 10/group), were placed under four types of crystalline core structure (Vita Enamic, Vita Suprinity, GC Ceresmart, Degudent Prettau Anterior). The specimens were irradiated for 40 seconds with an LED Soft-Start or pulse-delay unit or 20 seconds with a QTH unit. DC ratios were determined by using Fourier transform infrared spectroscopy (FTIR) after curing the specimen at 1 day and 1 month. The data were analyzed using the Mann-Whitney U test (for paired comparison) and the Kruskal-Wallis H test (for multiple comparison), with a significance level of P<.05. RESULTS. DC values were the highest for RelyX Ultimate Clicker light-cure specimens polymerized with the LED Soft-Start unit. The combination of the Vita Suprinity disc and RelyX Ultimate Clicker dual-cure resin cement yielded significantly higher values at both timepoints with all light units (all, P<.05). CONCLUSION. Within the limitations of this study, we conclude that the DC of RelyX Ultimate Clicker dual-cure resin cement was improved significantly by the use of Vita Suprinity and the LED Soft-Start light unit. We strongly recommend the combined use of an LED light unit and dual-cure luting cement for monolithic ceramic restorations.

• Electronics and Telecommunications Trends
• /
• v.24 no.6
• /
• pp.61-76
• /
• 2009

LED는 2000년대에 들어서면서 생활 전반에 사용되기 시작하여 최근에는 자동차용 부품과 TV의 back light unit에 이르기까지 모든 분야에서 다양한 용도로 사용되고 있다. 본 기고에서는 이러한 LED의 기판을 포함한 에피, 칩, 그리고 패키지 기술의 중요한 이슈와 기술의 동향에 대하여 간략히 정리하였다. 상용화되어 사용되는 사파이어나 SiC 기판 이외에 연구개발이 진행중인 GaN 기판 기술 등을 소개하고, 에피 기술에서는 활성층과 클래딩층 성장 기술의 이슈들을 제시하며, 칩의 종류와 특성을 중심으로 droop 현상과 광추출 기술 등을 살펴보고, 다양한 패키지의 종류 및 특징 등을 포함하는 LED 분야의 기술 동향에 대하여 설명한다.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.1015_1016
• /
• 2009

최근 대체조명으로 Power LED가 각광받고 있다. 그러나 반도체 소자인 Power LED의 특성에 의해 기존의 정전압 제어방식으로는 적절한 제어에 어려움이 있다. 이러한 문제의 해결책으로 본 연구에서는 Power LED를 MCU(Micro Controller Unit)를 이용한 디지털 정전류 제어방법에 대하여 서술하였다.

• Electronics and Telecommunications Trends
• /
• v.28 no.6
• /
• pp.192-205
• /
• 2013

세계 각국은 자국의 안정적인 에너지 공급과 저탄소 녹색성장을 위해 장 단기적인 정책을 다양하게 펼치고 있다. 그 중 고효율, 친환경 광원인 LED는 국가의 에너지 정책 추진의 중요한 부분을 차지하고 있다. LED 조명은 기존 백열등 형광등 할로겐을 대체 할뿐만 아니라 휴대전화, 자동차, BLU(Back Light Unit) 등 다양한 분야에 적용할 수 있기 때문에 시장잠재력이 크다. 본고에서는 미국, 유럽, 중국, 일본의 LED 조명산업 관련 정책을 살펴 보고 정책적 시사점을 도출하고자 한다.

• Proceedings of the Optical Society of Korea Conference
• /
• 2007.07a
• /
• pp.325-326
• /
• 2007

• The Journal of the Korea Contents Association
• /
• v.21 no.6
• /
• pp.44-50
• /
• 2021

In this paper, we analyze the efficiency of light sources of CCFL and LED monitors. Cold Cathode Fluorescent Lamp (CCFL), which is widely used as a light source for LCD display, supplies a high voltage of 1,200[V] or more when it is initially driven. In addition, a constant normal voltage of 400 ~ 800[V] after lighting, and 3 ~ 6[ mA] is needed for a power circuit that can stabilize the current. Applying a high voltage causes a lot of stress on the inverter and generates a lot of heat in the cold cathode lamp, causing significant damage to the BLU (Back Light Unit), resulting in a burning phenomenon, which causes the screen to output normal colors when outputting the screen. We can not see the yellow output and the screen darkened. Therefore, in order to prevent such a symptom in advance, efficiency can be increased by using a Light Emitting Diode (LED) as the light source of the LCD display instead of a cold cathode fluorescent lamp (CCFL). As a result, it is shown that the LED method outperforms the CCFL method.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.12
• /
• pp.702-708
• /
• 2020

Recently, as LED display systems have become larger, research on effective power control methods for the systems has been in progress. This paper proposes a power control method to minimize power loss due to the difference in LED characteristics for each channel of a backlight unit (BLU) system. The proposed LED driver IC has a power optimization function and detects the minimum headroom voltage for constant current operation of all channels and linearly controls the DC-DC converter output. Thus, it minimizes power consumption due to unnecessary additional voltage. In addition, it does not require a voltage sensing comparator or a voltage generation circuit for each channel. This has a great advantage in reducing the chip size and for stabilization when implementing an integrated circuit. In order to verify the proposed function, an IC was designed using Cadence and Synopsys' design tools, and it was fabricated with a Magnachip 0.35um 5V/40V CMOS process. The experiments confirmed that the proposed power control method controls the minimum required voltage of the BLU system.

• Electronics and Telecommunications Trends
• /
• v.30 no.6
• /
• pp.42-49
• /
• 2015

질화물 반도체 기반 가시광 청색 Light Emitting Diode(LED) 기술은 디스플레이의 Back Light Unit(BLU)뿐 아니라 일반 조명에 활용되며 우리 실생활에서 매우 밀접하게 사용하고 있다. 가시광보다 짧은 파장을 가지는 자외선 LED의 경우 경화기 및 위폐감지기에 기존의 유해 가스를 사용하는 자외선 램프를 대체하고 있다. 자외선 광원의 또 다른 거대 시장으로 살균 및 정화, 의료 및 바이오 응용 시장에서 자외선 램프를 대체할 수 있는 자외선 LED 기술이 활발히 발전하고 있다. 본고에서는 이들 자외선광원 시장동향과 국내외 자외선 LED의 기술동향을 파악하므로 앞으로 연구개발의 방향을 모색하고자 한다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2009.05a
• /
• pp.157-159
• /
• 2009

LED BLU(Back Light Unit), based on MCPCB(Metal Core Printed Circuit Board) with anodizing oxide dielectric layer and improved thermal dissipation property, are presented. Reflecting cups were also formed on the surface of the MCPCB such that optical coupling between neighboring chips were minimized for improving the photon extraction efficiency. LED chips were directly attached on the MCPCB by using the COB (Chip On Board) scheme.