• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.3
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• pp.243-250
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• 2009

This paper provides an novel two-stage LED driver circuit for LED lighting equipment. The proposed driver circuit reduces voltage stress in LED driver circuit by using multi-level output voltage of PFC flyback converter. The proposed circuit satisfies IEC61000-3-2 class C regulation that is applied to lighting equipment over 25W and uses PWM to control brightness of wide extent. In this paper, the principle of proposed driver circuit is presented. A prototype has been built and tested. The experimental results are presented to show the validity of the proposed circuit.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.766-767
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• 2010

By using LED which is a light source which has been in the spotlight recently, the ring light for medical purposes was developed for shadowless shooting of local site in the affected area. The developed ring light was designed to be able to control the various quantity of light by using PWM (pulse width modulation) method, and by controlling each LED (light emitting diode) independently the regulation of color temperature and color rendering are possible. Also, the persistent light for continuous shooting of affected area and flash mode action for snap shooting are possible. In this study the response speed of momentary flash function was checked using interface circuit configured for momentary shadowless shooting of affected area.

• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.211-212
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• 2008

정보가전기기들의 대형화 제품개발 및 생산에 따른 전력소모가 극대화 되어있는 현실에 에너지소비를 줄이기위한 많은 연구들이 진행되고 있다. 그 중 LCD TV 분야는 전체 전력소비의 약 70% 이상이 Back-light에 의해 소비되므로 효율석인 Back-light 설계에 관한 관심이 증가하고 있다. 근래에 전통적인 CCFL 방식의 flack-light 구조에서 LED Back-light으로 점차 대체되어가고 있으며, 이러한 변화는 앞으로도 지속적으로 증가하기라 예상된다. 따라서, LED Hack-light의 효율적인 선력관기는 산업적 측면에서도 매우 주요한 부분이라 할 수 있다. 본 논문은 대형 TV의 에너지효율을 높이기위한 LED Rack-light 구성에 관한 요소들을 관계를 기술하고, 특히 Back-light 밝기제거를 통한 효율적인 전력관리를 실현위한 다채널 구동제어신호 생성에 관해 설명한다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2269.1_2270.1
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• 2009

본 논문에서는 원칩 마이크로컨트롤러와 ZigBee IC가 내장된 소형 모듈을 사용한 파워 LED의 디지털 조도제어 시스템의 설계 및 구현에 대해 중점적으로 기술한다. 파워 LED의 조광제어 및 특정 조도에서의 정전류 구동을 위해 전류피드백을 통한 디지털 PI 전류제어 및 PWM 구동방식을 행하였고, 시각적인 깜박거림 없는 충분한 주파수의 스위칭을 통해 부스트 컨버터를 연속도통모드로 동작시켰다. 2.4GHz의 주파수 대역을 이용하는 PAN (Personal Area Network) 형태의 ZigBee 무선모듈과 마이크로컨트롤러와의 UART 통신을 통해 조도제어를 위한 PWM 제어를 행하였다. 본 논문에서 제시한 파워 LED의 디지털 조도제어 시스템은 최근의 에너지 및 환경규제에 적합한 조명관련 응용분야에서 다양하게 적용될 것으로 판단된다.

• Journal of Advanced Navigation Technology
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• v.20 no.4
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• pp.265-274
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• 2016

In this study, the system was composed of the booster chopper and the power converter, which is a pulse width modulation (PWM) voltage inverter using a hybrid power generation system solar cell energy and wind force, Furthermore, in order to compensate the PWM voltage type inverter was linked with the general commercial power source, and through a normal operation of energy storage system (ESS), the system operated the LED Taxi Light by Wavelength according to Meteorological Changes at the airport in an efficient manner. The performance of the system was compared with the solar cell characteristics specification. In addition, for phase synchronization with the PWM voltage type inverter, the grid voltage was detected so as to operate the grid voltage and inverter output in the same phase and to connect the surplus electric power with the system. Finally, by developing a control circuit at the same time from which an excellent dynamic characteristics can be obtained through applying to the airport runway taxi light, it was concluded that a variety of taxi light can be pursued.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.91-93
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• 1993

This paper introduced an advanced PWM method to drive a variable speed AC motor. With this technique, a switching pattern is determined to minimize the error between a reference signal and feedback signal. In addition to its simplicity of implementation, the proposed technique has the advantage of control led constant voltage per frequency operation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.12
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• pp.1149-1153
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• 2006

We developed the equipment palpating cell proliferation using a high brightness LED. This equipment was fabricated using a micro-controller and a high brightness LED, and designed to enable us to control light irradiation time, intensity, frequency and so on. Especially, to control the light irradiation frequency, FPGA was used, and to control the change of output value, TLC5941 was used. Control stage is divided into 30 levels by program. Consequently, the current value could be controlled by the change of level in Continue Wave(CW) and Pulse Width Modulation(PWM), and the output of a high brightness LED could be controlled stage by stage.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.8
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• pp.390-396
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• 2002

This paper Presents to choose number of RGB LED through optical special quality analysis of RGB LED samples and to produce ratio of RGB LED for a stable color variation and white light. Also, it is to design of a simple switching circuit using some resistances and switching transistors that is able to operate each 16 RGB LED stably, and switching control circuit base on a microcontroller that would be suitable for colors variation patterns control more than about 64 patterns and colors variation more than about 100,000 colors using ON/OFF and Duty control.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.248-249
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• 2008

본 논문에서는 원칩 마이크로컨트롤러를 사용한 파워 LED 구동제어 시스템의 설계 및 구현에 대해 중점적으로 기술한다. 파워 LED의 조광제어 및 특정 조도에서의 정전류 구동을 위해 전류피드백을 통한 디지털 PI 전류제어 및 PWM 구동방식을 행하였고, 시각적인 깜박거림 없는 충분한 주파수의 스위칭을 통해 부스트 컨버터를 연속도통모드로 동작시켰다. 본 논문에서 제시한 파워 LED 구동을 위한 디지털 제어시스템은 최근의 에너지 및 환경규제에 적합한 조명관련 응용분야에서 다양하게 적용될 것으로 판단된다.

• 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.