• Journal of Advanced Navigation Technology
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• v.16 no.1
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• pp.70-75
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• 2012

LED-64 is a 64-bit block cipher proposed in CHES 2011 and suitable for the efficient implementation in constrained hardware environments such as WSN. In this paper, we propose a differential fault analysis on LED-64. In order to recover the secret key of LED-64, this attack requires only one random nibble fault and an exhaustive search of $2^8$. This work is the first known cryptanalytic result on LED-64.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.11a
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• pp.92-93
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• 2017

최근 IT 및 사이니지 기술을 포함한 여러 기술의 발전 형태가 융복합적 기술의 방향으로 전환됨으로서, 기술 간 장벽이 허물어지고, 상호 연관성을 갖게 됨에 따라 사이니지 및 IT기술이 접목된 새로운 융복합 기술에 대한 연구가 지속적으로 이루어지고 있다. 특히, LED 광원의 일종인 사이니지를 이용하여 광 데이터를 전송할 수 있는 기술에 대한 연구가 학계, 연구소 및 관련 산업체 등에서 지속적으로 진행되고 있는 상황이다. 이에 본 논문에서는 LED 전광판 사이니지를 이용하여 무선광통신이 용이한 LED 소재에 대한 연구를 진행하였다. LED 전광판 사이니지를 이용한 무선광통신 기술은 LED 광원이 지닌 특성을 토대로 RF방식 대비 높은 주파수 대역과 고속의 데이터 전송이 가능하기 때문에 높은 잠재력과 파급력을 통하여 무선통신 분야에서의 새로운 통신 척도로 활용될 수 있을 것으로 예상된다.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.1
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• pp.64-70
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• 2011

This paper presents a zero-transient current control method for PWM dimming of LED. Since the proposed LED current control method has no transient state, it features a high resolution, high linearity, and no current overshoot through LED along a wide dimming range. The operational principles of the proposed LED current control circuit are presented. To confirm the validity of the proposed method experimental results from a prototype circuit of the 46-inch LCD TV are given.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.2
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• pp.284-288
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• 2015

The color temperature flexibility-typed Lighting Emitting Diode(LED) lighting control system proposed in this thesis employs Pulse Width Modulation(PWM) technique to control the brightness of LED lighting. The LED lighting used as a light source has 20W downlight composed of two types of LED chips: one is Warm White and the other is Cool white. One multi-sensor module consisting an infrared sensor, an illumination sensor, and a temperature sensor was made, to which Bluetooth wireless communication technique was applied to enable a smartphone application to control lighting brightness and identify the information collected from the sensor. CS-1000, a spectroradiometer, was used to measure LED dimming control and the changing values of a color temperature in eight steps. According to a test, it was found that it was possible to change a color temperature from 3187K of Warm White LED to 5600K of Cool White LED.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.1
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• pp.64-68
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• 2015

In this paper, LED lighting system is realized by using Bluetooth wireless communications and smartphones. A bluetooth module with a lighting control function is manufactured by miniaturizing a development board of TI company and the volume of LED dimming system as a whole is reduced. And a trial product is materialized by designing a hardware composed of the manufactured bluetooth module, LED down light equipped with degree warm white and cool white, and 2-channel LED driver; and LED dimming software. The materialized trial product is controled in terms of the brightness and color temperature of LED light source using an application of a smartphone. The experiment showed that the users can easily control the intensity of illumination of LED light source by using the scroll bar of the applications of smartphones. In addition, the color temperatures of both warm white and cool white can be controlled, and when the color temperature of the trial product using the manufactured bluetooth module is compared with that of a trial product of TI company, they show the same color temperatures.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.1
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• pp.64-71
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• 2012

An efficient cooling system is an essential part of the electronic packaging such as a high-luminance LED lighting. A special technology, Pulsating Heat Pipe (PHP), can be applied to improve cooling of a sealed, explosion-proof LED light fixture. In this paper, the characteristics of the pulsating heat pipes in the imposed thermal boundary conditions of LED lightings were experimentally investigated and a PHP device that works free of alignment angle was investigated for cooling of explosion-proof LED lights. Five working fluids of ethanol, FC-72, R-123, water, and acetone were chosen for comparison. The experimental pulsating heat pipe was made of copper tubes of internal diameter of 2.1 mm, 26 turns. A variable heat source of electric heater and an array of cooling fins were attached to the pulsating heat pipe. For the alignment of the heating part at bottom, an optimum charging ratio (liquid fluid volume to total volume) was about 50% for most of the fluids and water showed the highest heat transfer performance. For the alignment of the heating part on top, however, only R-123 worked in an un-looped construction. This unique advantage of R-123 is attributed to its high vapor pressure gradient. Applying these findings, a cooling device for an explosion-proof type of LED light rated 30 W was constructed and tested successfully.

• KIEAE Journal
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• v.10 no.6
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• pp.33-39
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• 2010

Visual Environment and productivity are correlated. So we need to create a comfortable visual environment and maintain proper workplane illumination level. We can obtain lighting energy savings and comfortable visual environment using daylight and LED lights. In this study, we characterized the indoor illuminance level according to the sky condition and proposed dimming control strategy of LED lights. Energy savings in On/Off control mode are 40% at clear sky and 28% at intermediate sky. In dimming control mode, energy savings are 77.2% at clear sky and 64.1% at intermediate sky. Then we obtain the appropriate dimming control strategy of LED lights based on data. Dimming rates are 0-14.2-80(min-avg-max, %) for LED 1, 0-19.9-60% for LED 2 and 30-61.4-90% for LED 3. Lighting energy savings are 68.2% for LED dimming system applied this control method.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.64-66
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• 2020

친환경적이고 수명이 길며 높은 효율을 가지고 있는 LED(Light Emitting Diode) 조명은 각광 받고 있다. LED는 응용 분야별로 필요한 용량에 따라 다양하게 정하지 않고 용량을 한가지로 표준화하여 직, 병렬로 연결하여 모듈 형태로 사용하고 큰 용량이 필요한 경우, 여러 개의 모듈로 이용하는 특징을 갖는다. 따라서 LED 구동하기 위한 컨버터는 LED 모듈을 최소 하나에서 여러 대를 구동할 수 있는 PFC 및 DC/DC 컨버터를 요구한다. 기존 단일 출력 컨버터로 LED 모듈을 구성하면 LED 시스템의 높은 효율, 높은 전력 밀도, 대용량화 및 활용도가 떨어지며 효과적으로 유지 보수가 어렵다는 문제점이 있다. 또한, 다중 출력 LED 컨버터는 각 출력이 정전류 특성을 유지하고 LED 보호 기능을 가지려면 독립적인 컨버터가 채널마다 필요하게 된다. 이에 본 논문은 다중 출력으로 복수의 LED 모듈을 문제없이 구동할 수 있는 LLC 공진 컨버터에 관한 연구이며 이를 시뮬레이션을 통해 확인하였다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.64-69
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• 2007

실내조명의 조도 기준을 만족하는 LED Bulb를 개발하기 위하여 LED 개수를 선정하고, 실내 전반 조명에 적합한 배광을 실현하기 위한 렌즈설계를 하였다. 그리고 LED로부터 발산되는 열을 최적화하기 위한 방열설계를 행하여 주위온도 $50^{circ}C$ 이내에서 동작 가능하도록 하였다. 또한 시제품의 외함에 내장되어 질 수 있는 소형의 20[W]급 전원회로를 설계하고, 시제품을 직접 제작하였다. 시제품의 전기적, 광학적 성능은 CFL의 성능과 거의 동일하다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1761-1767
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• 2015

This paper deals with the solar tracking performance using a small heliostat, the light reduction rate of the sun light, and the performance of uniform irradiation of LED light for a plant factory. A high precision encoder is attached to the heliostat to improve tracking accuracy. As a result, our heliostat-based solar tracking systems track efficiently the movement of the sun light in experimental tests. The reduction rate of the sun light in the plant factory is then measured by using an illumination sensor. The average reduction rate is 4.29%, which represents lower light reduction rates. In uniform irradiation tests of LED light, sixteen points are measured, and overall deviations of irradiation were within eight percents.