• Journal of the Semiconductor & Display Technology
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• v.18 no.4
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• pp.51-56
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• 2019

LuAG:Ce(Lu₃Al₅O₁₂:Ce³⁺) nano phosphor were synthesized by applying the coprecipitation method. It is used to increase the color rendering of phosphor ceramic plate for high power LEDs and laser lighting. Internal quantum efficiency and absorption of LuAG:Ce nano phosphor are 51.5 % and 64.4 %, respectively, which is higher than the previously studied nano phosphors. The maximum absorption wavelength of this phosphor is 450 nm blue light, and the emission wavelength is 510 nm. The emission wavelength shifted to longer wavelength when the concentration of Ce increased in the heat treatment of the reducing atmosphere. Thermal quenching of LuAG nano phosphor was 70 % at 200 ℃, it was explained by their significant quenching of all raman scattering modes, implying the restriction of electron-phonon couplings caused by their defects.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1268-1276
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• 2016

A triode for alternating current (TRIAC) dimming light emitting diode (LED) driver, which adopts a variable switched capacitor for LED dimming and LED power regulation, is proposed in this paper. The proposed LED driver is power efficient, reliable, and long lasting because of the TRIAC switch that serves as its main switch. Similar to previous TRIAC dimmers for lamps, turn-on timing of a TRIAC switch can be controlled by a volume resistor, which modulates the equivalent capacitance of the proposed variable switched capacitor. Thus, LED power regulation against source voltage variation and LED dimming control can be achieved by the proposed LED driver while meeting the global standards for power factor (PF) and total harmonic distortion (THD). The long life and high power efficiency of the proposed LED driver make it appropriate for industrial lighting applications, such as those for streets, factories, parking garages, and emergency stairs. The detailed analysis of the proposed LED driver and its design procedure are presented in this paper. A prototype of 80 W was fabricated and verified by experiments, which showed that the efficiency, PF, and THD at V_s = 220 V are 93.8%, 0.95, and 22.5%, respectively; 65 W of LED dimming control was achieved with the volume resistor, and the LED power variation was well mitigated below 3.75% for 190 V < V_s < 250 V.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.4
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• pp.388-393
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• 2018

In this paper, We developed a high efficiency reflector integrated type 50W AC direct connection type engine to realize miniaturization and weight reduction of product without using SMPS and to design a multistage varistor circuit Reduced costs by reducing the number of parts High reliability is achieved by using a circuit structure that does not use an electrolytic capacitor, thus increasing the lifetime of the LED. In addition, it is possible to manufacture an AC direct-coupled type driving device by using an IC semiconductor and apply an AC direct-coupled type driving device integrated with a reflector so that the lifetime of the device can be fully utilized for the lifetime of the LED, A light source having a plurality of light emitting diode channels including a plurality of light emitting diode channels arranged in series is driven with a rectified voltage.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.2
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• pp.137-141
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• 2015

The purpose of this study is examining thermal dissipation materials for the lighting and radiate efficiency improvement of 8W LED and confirming the properness of the thermal dissipation materials for LED heat sink. Solid Works flow simulation on 8W class COB was done based on the material characteristics of thermal conductive polymer materials. According to the result of simulation, Al had better thermal dissipation performance than PET. Highest temperature was $7.6^{\circ}C$ higher while lowest temperature was $7.8^{\circ}C$ lower. The test on the heat sinks made by the materials, highest temperature was $4.1^{\circ}C$ higher and lowest temperature was $3.9^{\circ}C$ lower. It is possible to confirm that Al heat sink has better thermal dissipation efficiency because it has better dispersion of heat generated at junction temperature and less heat cohesion. The weight of PET heat sink was reduced than Al heat sink by 46.9% by the density difference between Al and PET. In conclusion, thermal dissipation performance of thermal conductive polymer is lower than Al material however, it is possible to lighting heat sink because thermal conductive polymer has better formability, has lower specific weight and enables various design options.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.4
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• pp.929-934
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• 2010

Improvements in characteristics of a single junction AlGaAs/GaAs solar cell are observed by capping a PMMA lens on it. In order to show the effect of the lens, characteristics of a single junction AlGaAs/GaAs solar cell before and after the lens formation are compared under the one-sun illumination condition ($100mW/cm^2$). Characteristics of the solar cell under very weak illumination condition (about 1200 lux) is also measured with the lighting of a fluorescent desk lamp. About 5% of cell efficiency is improved after the capping of PMMA lens on the single junction AlGaAs solar cell and $83\;{\mu}m/cm^2$ of electrical power was generated with the lighting of a desk lamp.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3
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• pp.480-487
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• 2013

In this study, we researched the LED source MR16,which maintains the strong points of an ordinary MR16 while compensating for its weak points. The optical system composition of the LED MR16 includes four aspherical lens per sheet and a patterned reflector. The aspherical optical system and reflector were designed using optical software, and the performance was estimated using a lighting simulation program. Finally, a prototype was manufactured after analyzing the simulation data, and the reliability of the simulation results was estimated using a comparative analysis of the designed data and measured data.

• Transactions on Electrical and Electronic Materials
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• v.15 no.4
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• pp.201-206
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• 2014

LED lighting,considered to be a new growth industry, has attracted a great deal of attention due to its higher illumination and longer life time than existing light sources. In this study, high-efficiency and long-life LED fog lamps for automobiles were developed, which can substitute the existing 27 W halogen fog lamps for a used car market. For this purpose, the number of LED modules, the body, heat sink, and the output of the fog lamp were first optimized through a numerical analysis. Then, a 10 W-class LED fog lamp was prototyped based on the optimized numerical model, and the performance of the fog lamp was successfully verified through the experiments.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.12
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• pp.1078-1083
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• 2009

Generally Lighting system consists of lamp and luminaire. When a fluorescent lamp is installed in luminaire, power and light output is changed by ambient temperature. Particularly electrodeless lamp depends on the changes that are mercury pressure with amalgam temperature and magnetic properties with ferrite temperature. It has finally influence on optical efficiency. In this study, the temperature change of ferrite and cold spot, vessel are measured at transitional state and then same characteristics are measured with increase of ambient temperature. At transitional state, luminous flux is related to temperature change of cold spot that compare with behavior of mercury pressure and light output. At increase of ambient temperature, we analyzed change that efficiency and electrical, optical characteristics of elecrodeless lamp are related to ferrite core and cold spot temperature.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.504-505
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• 2011

Decreasing actual greenhouse gas will be difficult if it is not solved addressed in architectural fields. Zero emission building or zero energy building, maximize the efficiency of energy, which means the building can operate by their own renewable energy facility without any other supplying. To be a zero emission building, a building needs realization of high efficiency low energy consumption, construction of building its own energy production facilities and lastly a power grid connection. According to increasing of DC load about TV, LED lighting, computer, IT in building for living and business, it is expected the save of energy when the system of AC power distribution change into the system of DC power distribution. Renewable energy exists a big different rate produced by outside environment. When electrical power overproduce, it can supply for system. Otherwise, if electrical power produce less, it can receive supply from system. Send and receive power can lead to zero to annual standard. This paper shows the simulation about efficient control of power conversion which is related to DC power distribution of architecture and DC output of renewable energy by using L-type converter.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.4
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• pp.303-308
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• 2016

A light-emitting diode (LED) has been increasingly applied to various industrial fields and general lightings because of its high efficiency, low power consumption, environment-friendly characteristic and long lifetime. To drive this LED lighting, various types of power converters have been applied. Also, power factor correction (PFC) techniques play an important role in the power supply technology. In this paper, design and control of a DCM interleaved boost PFC converter is discussed. The proposed converter can reduce current ripples at input and output side by cancelling an each phase of inductor currents. Since the IC does not require the auxiliary winding of inductor for current detection, simple PFC circuit is achieved. Therefore, it contributes to increase efficiency and downsize the whole system volume, cost. Also, the performance of the proposed system is demonstrated through experiments.