• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.11
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• pp.2043-2047
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• 2010

This study is to solve problems of depletion of RF bandwidth frequency, confusion possibility, security that current wireless communications system have and is to confirm possibility of applying next generation network. To solve problems of current wireless communications system, visible light communications system for power line communications using ATmega16 Microcontroller is was realized and receiver property was analyzed. PLC exclusive chip APLC-485MA, Microcontroller ATmega16, 5pi bulb type LED and high flux LED, visible light receiving sensor LLS08-A1 were used for transmitter and receiver. Performance was analyzed by designed program and an oscilloscope. It was showed average 20% improved receiver rate rather than bulb type LED in the case of high flux LED through voltage change rate on communication distance and LED type of distance between 10 to 50 cm. The blue LED showed the best performance among measured LED types with above 10% of voltage decreasing rate. But As it gradually becomes more distant, the precise date was difficult to obtain due to weak light. To overcome these sort of problems, specific values such as changing conditions and efficiency value relevant to light emitting parts and visible light receiving sensor should be calculated and continuous study and improvements should also be accomplished for the better communications condition.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.9
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• pp.8-13
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• 2011

In this paper, a mathematical model of the power LED system including the drive circuit will be presented to control the power LEDs current. Using this mathematical model, the constant current adaptive controller will be designed. A constant current drive circuit for power LEDs will be configured using Buck-type converter. Precise constant current controller design is enabled by presenting the mathematical model of power LEDs including the current driving circuits. Using the mathematical model of power LEDs and its drive circuits, the constant current adaptive controller will be designed to obtain the robustness for the parameter uncertainties. In order to verify the validity of the proposed controller, computer simulations are performed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.10
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• pp.1-8
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• 2014

Heat dissipation of the high power LED is a critical issue. To estimate the junction temperature of the LED chip is most important in characterizing the heat dissipation, but it is impossible to directly measure it. In this study, surface temperatures of the 12.8W LED bulb was measured for 5 points using a data logger and compared with the simulated results using a thermal simulator based on FVM (finite volume method) to secure a reliability of the simulation. Effects of some factors such as lens, emissivity and air inlet were investigated using simulation works and then the results were analysed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.1
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• pp.73-78
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• 2008

A resistor network model for the horizontal AlInGaN LED was investigated, The parameters of the proposed model are extracted from the test dies and $350{\mu}m$ LED, The center of the P-area is the optimal position of a P-electrode by the simulation using the model. Also the optimal chip size of the LED for the new target current was investigated, Comparing the simulation and fabrication result, the errors for the forward voltage and the light power are average 0,02 V, 8 % respectively, So the proposed resistor network model with the linear forward voltage approximation and the exponential light power model are useful in the simulation for the horizontal AlInGaN LED.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.598-599
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• 2012

본 논문은 전압제한 고효율 AC입력 LED 드라이버에 연구에 관한 것이다. 최근 이산화탄소 배출 저감과 고효율 LED 조명이 일반화 되면서 고효율, 장수명, 소형화에 대한 요구가 커지고 있다. LED를 구동하기 위해 SMPS (Switching Mode Power Supply)를 사용하는 경우 역률을 높이기 위해서 별도의 역률 개선부를 포함하고 있어야 하며 전해커패시터 역시 사용되어야 한다. 이 방식은 가격의 상승과 전해커패시터 사용에 의해 수명 저하라는 단점이 있다. 본 연구에서는 이러한 단점을 보완하여 수명 저하를 일으키는 전해커패시터와 별도의 역률 개선부 없이 LED에 정전류를 공급하고 역률을 향상시킬 수 있는 LED 드라이버 회로를 제안하고 이를 실험으로 검증한다.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.363-364
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• 2010

Most LED drivers uses current control method to adjust LED current. Using AC power grid such as off-line converter, Buck topology is popular because input voltage of LED driver is much higher than LED output voltage. Normally DCM current control is more popular than CCM current mode control in the range of below 50W, But DCM characteristics are dependent on the input voltage variation. This paper deals with what should be considered in DCM for LED driver with valley fill circuit.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.8
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• pp.700-705
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• 2013

If LED lighting is to be used in home networking, a home gateway and power line communication are needed in delivering data. In addition, an appropriate multiple access scheme reflecting LED's property is required. In this paper, a home networking system that can serve wide in-building area by integrating PLC and VLC, is proposed and implemented, then its performance is measured. A binary CDMA is used in the multiple access since this scheme is good for nonlinear device like LED, while infrared is used in the upstream transmission.

• 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 Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.4
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• pp.275-283
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• 2021

In this study, a driver IC for an AC-powered LED that can be manufactured with a low voltage semiconductor process is designed and the performances of the driver IC were simulated. In order to manufacture a driver IC that operates directly at AC 220V, a semiconductor manufacturing process that satisfies a breakdown voltage of 500V or higher is required. A semiconductor manufacturing process for a high-voltage device requires a much higher manufacturing cost than a general semiconductor process for a low-voltage device. Therefore, the LED driver IC is designed in series so that it can be manufactured with semiconductor process technology that implements a low-voltage device. This makes it possible to divide and apply the voltage to each LED block even if the input voltage is high. The LED lighting circuit shows a power factor of 96% at 220V. In the pnp transistor circuit, a very high power factor of 99.7% can be obtained, and it shows a very stable operation regardless of the fluctuation of the input voltage.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1349-1354
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• 2021

An All-in-one LED lantern is a light device to determine the fairway of ships in operation. The current all-in-one LED lantern powered by solar energy is challenged by insufficient power capacity due to limited sun hours. This article presents an all-in-one 9-Nautical mile LED lantern driven by solar and wind power that is abundant maritime renewable energy. Furthermore, the remote smart monitoring system is developed. A smart control system capable of remote control of the lantern was implemented by using the LED lantern device and monitoring system as IoT. This technology that realtime condition monitoring and remote control are developed for safe ship navigation. We expect that maintaining the accuracy and consistency of LED lanterns prevents marine accidents and reduces social costs.