• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1556-1557
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• 2007

LCD BLU에 광원의 수명을 측정하고, 고장모드를 분석하기 위해서는 광원을 구성하고 있는 각각의 성분 중에서 광원 자체를 구성하고 있는 R/G/B 광원에 대한 Burn-in test 및 고장모드를 분석하였다. LCD BLU에 있어서 R/G/B LED광원의 역할은 BLU 자체의 수명과 성능에 가장 큰 영향을 미친다. 서로 각각 사용조건하에서의 수명과 성능의 차이에 따라서 BLU 자체의 수명이 결정된다. 이를 평가가기 위해 LED device에 대한 가속수명테스트를 위한 Burn-in test를 실시하였으며, 발생한 고장모드를 분석하였다. 분석결과 누설전류 증가로 인한 불량이 주로 발생하였다. 누설전류 증가를 평가하기 위해 Photo emission microscope(PHEMOS-1000, MoDooTEK Inc.)을 이용하여 저전류에서의 LED chip의 누설전류에 의한 발광을 관찰함으로 인해, LED chip의 신뢰성 및 평가 기준이 됨을 알 수 있다.

• 산업기술연구
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• 제31권A호
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• pp.95-101
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• 2011

According to recent technological developments in high-power LEDs, the stage lighting is one of most important areas to apply power LED system. Moving light for color rendering of stage uses the RGBW(red, green, blue, white) color mixing method. LED moving light system needs to have a wide range of dimming control as enough to operate at very low power. Also LED dimming system should not be induced color-shift and flicker in camera. This paper is experimentally verified the LED Moving Light driving circuit of 200Watt level designed to satisfy the above characteristics which applied the DC current-controlled and PWM mixed dimming method.

• 산업기술연구
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• 제32권A호
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• pp.103-107
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• 2012

Due to improvement of the semiconductor technology, the LED replaces the conventional lighting source and LED drivers have been studied and developed. The LED is driven by the constant current control method according to its characteristics. For the constant current control method, the linear regulator and the switching regulator is used. The switching regulator is usually used to LED drivers because it has specific characteristics as the wide input dynamic range and the high efficiency. In this paper, we have described the principle and the implement of the switching regulator, using the drive IC and the low cost DSP chip. Also, both methods have been implemented and its electrical characteristics had almost same experimental results in the steady state and the transient state.

• 반도체디스플레이기술학회지
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• 제18권1호
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• pp.10-14
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• 2019

In this study, we synthesized two $Y_3Al_5O_{12}:Ce^{3+}$ phosphors ($7{\mu}m$-sized and $2{\mu}m$-sized YAG) with different sizes by controlling particles sizes of starting materials of the phosphors for white LED. In the smaller one ($2{\mu}m$-sized YAG), its photoluminescence intensity in the reflective mode was 63 % that of the bigger one ($7{\mu}m$-sized YAG); the quantum efficiencies were 93 % and 70 % for the smaller and the bigger ones. Two kinds of white LED packages with the same color coordinates were fabricated with a blue package (chip size $53{\times}30$) and two phosphors. The luminous flux of the white LED package with the smaller YAG phosphor was 92 % of that with the bigger one, indicating that the quantum efficiency of phosphor dispersed inside LED package was higher than that of the pure powder. It was consistently confirmed by the optical simulation (LightTools 6.3). It is notable according to the optical simulation that the white LED with the smaller phosphor showed 24 % higher luminous efficiency. If the smaller one had the same quantum efficiency as the bigger one (~93 %). Therefore, it can be suggested that the higher luminous efficiency of white LED can be possible by reducing the particle size of the phosphor along with maintaining its similar quantum efficiency.

• 한국생산제조학회지
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• 제21권3호
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• pp.487-492
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• 2012

In this study we researched a spotlight in LED lighting. Ordinary LED spotlight was manufactured with characterized property of traveling straightness of LED light source, but multiple use of shell type LED, a yellow band has formed caused by light source interference between the LED. Also, there was a high miscellaneous light efficiency with losing light source homogeneity and efficiency due to light source control uneasiness. The study uses aspheric reflector and aspheric lens, so we can control the light source of LED spotlight with effectively and we reached surface light source by using COB/COM for LED module. Furthermore it can change its use by a reduced scale of light system. It has been designed to make its various application from low power consumption of bicycle lamp, up to high power consumption of automobile lamps and lighthouse.

• International Journal of Internet, Broadcasting and Communication
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• 제9권1호
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• pp.42-49
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• 2017

Despite the government's various safety measures, the number of safety accidents continues to rise and the interior is more likely to occur indoors than outdoors. Safety accidents involving young children account for more than 70 % of the safety accidents in the safety accidents, and the ratio of safety accidents in the classroom or classroom is more than 50 %. In this thesis the author proposes the system managing the accidents notification service using LED lighting and access entry control. Utilizing IoT technology, remote control or access can be controlled remotely by controlling multiple lights and entrances from each room and by means of a number of lighting and entrances. By monitoring and analyzing real-time status via server PC and mobile interface, it can control the maximum control and incident prevention, automatic control, and automatic control.

• 감성과학
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• 제18권2호
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• pp.45-54
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• 2015

본 연구에서는 LED 광원에 대하여 재실자의 업무 효율성과 에너지 저감 효과를 알아보기 위한 실험을 실시하였다. 이를 위해 LED 광원의 특성인 펄 스 폭변조(PWM, pulse width modulation)와 조도(lux)를 제어하여 총 9가지의 다양한 조명환경을 구성하였다. LED 조명의 펄스변조 비율은 각각 R:G:B=1:1:1, R:G:B=4:1:5, R:G:B=8:7:7으로 하였으며, 조도는 각각 400 lx, 700 lx, 1000 lx 으로 설정하였다. 또한, 실내환경은 온도 $20{\sim}24^{\circ}C$, 습도 50~60%, 착의량 1 clo 로 설정하였다. 각각의 주어진 9개의 조명환경에서 업무 효율성과 에너지 소비에 대해 분석하였다. 업무 효율성 분석을 위해 오류검색수정 작업을 실시하였으며, 에너지 소비 분석을 위해 각 조명환경에서 누적 소비전력을 측정하였다. 제안한 조명환경을 통해 실험한 결과, 업무 효율성은 400 lx 보다 700 lx 이상에서 정확도 및 소요시간의 효율이 좋았으며, 소요시간의 경우 제안한 펄스변조 R:G:B=8:7:7 에서 가장 좋은 효율을 나타냈다. 또한, 각각의 조도에 대한 소비전력은 펄스변조 R:G:B=8:7:7 > RGB=1:1:1 > R:G:B=4:1:5의 순으로 낮게 나타났다. 따라서, 본 논문에서 제안한 펄스 폭 변조 효과가 업무효율성 및 에너지 저감에 영향을 미치는 것을 확인할 수 있었다.

• 한국생산제조학회지
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• 제26권3호
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• pp.328-336
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• 2017

The exit surface of a lens is designed using a three-dimensional free-form expression in order to easily modify a curved surface. This enables the design of numerical values and mathematical things using three-dimensional free-form expression, and enhances precision because it can be fine-tuned via numerical control. The standard of "Classification of Luminaire Light Distribution" for outdoor lighting fixtures by IESNA is adopted in order to examine the correlation between three-dimensional free-form surface expression and lighting performance. The variation of light distribution type and range is analyzed using the values of maximum light intensity and 50% light intensity. The actual tolerance occurs owing to parameters such as the thickness of the lens, the distance between LEDs, and the movement of the center of the incident surface; the effects of changes in these parameters on the performance are compared and analyzed.

• International Journal of Advanced Culture Technology
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• 제8권1호
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• pp.207-212
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• 2020

The human centric lighting (HCL) control is a major focus point of the smart lighting system design to provide energy efficient and people mood rhythmic motivation lighting in smart buildings. This paper proposes the HCL control using indoor surveillance camera to improve the human motivation and well-beings in the indoor environments like residential and industrial buildings. In this proposed approach, the indoor surveillance camera video streams are used to predict the day lights and occupancy, occupancy specific emotional features predictions using the advanced computer vision techniques, and this human centric features are transmitted to the smart building light management system. The smart building light management system connected with internet of things (IoT) featured lighting devices and controls the light illumination of the objective human specific lighting devices. The proposed concept experimental model implemented using RGB LED lighting devices connected with IoT features open-source controller in the network along with networked video surveillance solution. The experiment results are verified with custom made automatic lighting control demon application integrated with OpenCV framework based computer vision methods to predict the human centric features and based on the estimated features the lighting illumination level and colors are controlled automatically. The experiment results received from the demon system are analyzed and used for the real-time development of a lighting system control strategy.

• KIEAE Journal
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• 제15권4호
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• pp.77-84
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• 2015

Purpose: In 2008, As the green growth policy was presented, Green Building is made any effort to propagation. In this paper, the respective technologies that are able to considerably reduce the energy demands for heating, cooling, hot-water, lighting and ventilation among the variety of technologies were selected. Method: Design factors such as (1) External insulation, (2) Triple glazing window, (3) LED lighting, (4) External venetian blind, (5) Geothermal and (6) Heat recovery ventilator were derived. In addition, energy saving effects in terms of energy demand, energy consumption and energy cost were investigated using EnergyPlus, building energy analysis tool. Result : The results were as follows. (1) It can be seen that high insulated triple glazing window, heat recovery ventilator and external insulation technology is excellent for energy demand. (2) Unlike energy demand, saving effect of energy consumption and energy cost was shown in order of Geothermal > Triple Window > Heat recovery Ventilation> Insulation> LED Lighting > EVB Blind.