• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.135-140
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• 2013

This paper deals with noise reduction on a light source driving board in a projector. We analyze causes of noise/vibration in the circuit with the present increasing use of LD and LED driving boards. The main source of noise is the MLCC in the driving board. Our aim is to investigate how the mechanical arrangement of the circuit elements affects noise reduction. The result of our experiment shows that noise can be reduced by symmetrical arrangement and slots in PCB. This result is expected to facilitate a variety of applications for manufactures without a need to change circuit elements.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.1
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• pp.205-210
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• 2020

Thanks to the shift in awareness of environmentally friendly energy and government initiatives, practical light-emitting diode(LED) lighting fixtures have emerged and are being distributed, resulting in very large energy savings. However, in actual use of LED lighting, it is possible to use it as an individual, but when using a large street light or a whole home lighting, the whole lighting system is realized due to various problems such as efficiency, stability, and reliability. Doing so has several problems. Although AC-LED has been developed recently to solve safety problems such as heat generation phenomenon of the conventional DC-LED, it also has various problems such as quality safety and reliability, which are difficult to use as outdoor lighting using existing AC Power. This happens. Accordingly, the appropriate power for AC-LED should be developed and applied, and the emergence of such LED lighting will play a role as a tool that can overcome the limitations of existing LED lighting and implement sustainable energy saving.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.510-511
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• 2017

In this paper, we have studied to minimize the lifetime and fault occurrence of LED fixtures, which have a short lifetime and frequent faults. In the current LED chip, the lifetime is semi-permanent, but compared to the lifetime of the LED chip, Drivers do not last long. In recent years, low-priced LED illuminators such as those from China have entered the market, and many consumers are perceiving LED illuminators. In order to solve these problems, we designed an LED illuminator of 25W class by using AC Direct IC, which has a longer lifetime than the conventional driver, by removing the electrolytic capacitor in the LED driving driver which is the cause of the failure.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.1
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• pp.28-34
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• 2010

The pulse width modulation(PWM) method has been generally used as conventional method controlling luminance of LED(light emitting diode). PWM method as analog method with a relation that duty ratio of LED be proportional to luminance has weak point that it is not compatible with digital method of communication etc. In this paper, a experiment is conducted which the luminance of RGB LED be controlled by digital method. For this, the LED digital control system is developed which consist of LED driving circuits and digital logic circuits. By controlling the number of pluses on RGB LED versus digital input, various lighting colors is implemented and digital codes are optimized in order that measured x, y chromaticity coordinates of lighting colors are comprised in the CIE chromaticity coordinates area of targeted lighting colors. The result of this study can be utilized usefully in research on implementing full color by using remote control of LED lamp with digital communication.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.9 no.1
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• pp.17-21
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• 2015

There have been sustained developments of advanced technologies using traffic safety facilities recently and techniques for identifying failure modes and devices which could result in fatal outcomes. The purpose of this research is aimed at improving the driving conditions in advance through analyzing the IT convergence, driving education, researches for vehicles, field of construction and robotics. The researchers evaluate on usability tests of the driving with 26 candidates through focusing on safety, convenience, efficiency, effectiveness. Using specialized LED panel to enhance driving performances of disabled people are for cautious road conditions like foggy weather or heavy rain. As a result, there were improvements in the driving conditions, and candidates reported this system was helpful. It allows them for maintaining proper driving all times and was especially informative for people with low vision or visually impaired. This system plays a pivotal role as a prevention mechanism not only for regular drivers but also for further delict of traffic violations or accident offenders who already have former record on tort.

• Journal of the Korean Vacuum Society
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• v.20 no.4
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• pp.280-287
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• 2011

The heat temperature of a light emitting diode (LED) is investigated with the thermoelectric device (TED). The Peltier effect of the thermoelectric device is used to control the heat radiation and the junction temperature of high-power LEDs. For the typical specific current (350 mA) of high-power (1 W) LEDs, the LED temperature and the p-n junction temperature become $64.5^{\circ}C$ and $79.1^{\circ}C$, respectively. For 0.1~0.2 W driving power of TED, the LED temperature and the junction temperature are reduced to be $54.2^{\circ}C$ and $68.9^{\circ}C$, respectively. As the driving power of the TED increases over 0.2 W, the temperature of LED itself and the junction temperature are increased due to the heat reversed from the heat-sink to LED. As the difference of temperature between LED and the heat-sink is increased, the quantity of reversed heat becomes larger and it results to degrade the cooling capability of TED.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.7-8
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• 2013

본 논문에서는 영전압 스위칭 탭인덕터 부스트 컨버터를 제안한다. 기존 컨버터는 DCM구간에 MOSFET의 Coss과 RC 스너버 및 탭인덕터의 공진에의해 MOSFET 양단에 전압 오실레이션이 발생하면서 턴온 시점에 따라 MOSFET 발열이 결정된다. 그래서 부하 변동과 부품편차와 무관하게 항상 최저전압조건에서 턴온하여 MOSFET의 발열을 저감하는 회로를 제안한다. 본 논문에서는 제안된 부스트 컨버터의 동작원리를 이론적으로 해석하고, 시제품 제작 및 실험을 통해 타당성을 검증한다.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1487-1490
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• 2008

mSilica developed a scalable integrated circuit solution for driving multiple arrays of LEDs to backlight TFT-LCD panels. The drivers incorporate adaptive power control of the DC-DC power supply powering the LEDs to improve the efficiency while synchronizing PWM dimming with video timing signals VSYNC and HSYNC to reduce motion blur.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.402-403
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• 2009

A variety of power reduction technologies is introduced and the benefits of the technologies are discussed. PenTile$^{(R)}$ DBLC (Dynamic Brightness LED Control) combined with SABC (Sensor-Based Adaptive Brightness Control) enables to achieve the average LED power consumption to one third. The panel power reduction of 25% can be achieved with low power driving technology, ALS (Active Level Shifter). MIP (Memory In Pixel) is expected to be useful in transflective display because the whole display area can be utilized in reflective mode with power consumption of 1mW.

• Journal of the Semiconductor & Display Technology
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• v.21 no.1
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• pp.50-55
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• 2022

Due to the wavelength shift problem of micro LED caused by the change of current density, the active matrix driving pixel circuit that is used in OLED cannot be applied to micro LED displays. Therefore, we need a gray scale method based on modulation of duration time of light emission. In this study, we propose the PWM-controlled micro LED pixel circuit based on CMOS thin film transistors (TFTs). By adopting CMOS inverter structure, we can reduce the number of storage capacitors from the circuit and make the operating speed of the circuit faster. Most of all, our circuit is designed to make operating speed of PWM circuit faster by adopting feedback effect through double gate TFT structure. As a result, it takes about 4.7ns to turn on the LED and about 5.6ns to turn it off. This operating time is short enough to avoid the color distortion and help the precise control of the gray scale.