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Wen, Minzhen (author), Ibrahim, Mesfin Seid (author), Meda, Abdulmelik Husen (author), Zhang, Kouchi (author), Fan, J. (author)High-power white light-emitting diodes (LEDs) have demonstrated superior efficiency and reliability compared to traditional white light sources. However, ensuring maximum performance for a prolonged lifetime use presents a significant challenge for manufacturers and end users, especially in safety–critical applications. Thus, identifying...journal article 2024
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Liu, Minne (author), Ibrahim, Mesfin S. (author), Wen, Minzhen (author), Li, Sheng (author), Wang, An (author), Zhang, Kouchi (author), Fan, J. (author)Spectral power distribution (SPD) is the radiation power intensity at different wavelengths, containing the most basic photometric and colorimetric performance of the illuminant, which is able to predict the lifetime of LEDs. This paper proposes an SPD model assisted by machine learning algorithms to detect the early failure of white LEDs. The...conference paper 2023
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Chen, Wei (author), Chen, Ye (author), Cao, Yixing (author), Cui, Z. (author), Fan, Xuejun (author), Zhang, Kouchi (author), Fan, J. (author)In a light-emitting diode (LED) package, silicone encapsulant serves as a chip protector and enables the light to transmit, since it exhibits the advantages of high light transmittance, high refractive index, and high thermal stability. However, its reliability is still challenged under harsh operation conditions. In this study, the optical...journal article 2022
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Ji, Liangzheng (author), Zhang, Kouchi (author), Zhang, Jing (author), Liu, Pan (author)Micro LED display technology has been spotlighted as the most promising technology compared to LCD and OLED. Its excellent advantages include higher brightness, self-illumination, higher resolution, lower power consumption, faster response, higher integration, higher stability, thinner thickness, longer life, etc. In terms of the unique benefits...conference paper 2022
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Feng, Shuo (author), Jiang, Tao (author), Chen, Wei (author), Fan, Xuejun (author), Zhang, Kouchi (author), Fan, Jiajie (author)As a core packaging material of light color conversion, phosphor/silicone composite plays an indispensable role in light emitting diode (LED) packaging. At present, commercial LED packages mainly use blue LED chips to stimulate Yttrium Aluminum Garnet (YAG) yellow phosphor to reach a white color. However, (Ca,Sr)AlSiN 3 :Eu 2+ (CSASN) red...conference paper 2022
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Lu, Zhiwei (author), Li, Xiaoling (author), Wei, Jinxiu (author), Cai, Miao (author), Yang, Daoguo (author), Zhang, Kouchi (author)UVC-LED is known as a deep ultraviolet LED. The application development and disinfection efficiency of UVC-LED modules are important problems encountered when UVC-LED products are rushed into commercialization. In this article, a specific disinfection experiment with a UVC-LED module was combined to analyze the disinfection efficiency. UVC-LEDs...conference paper 2022
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Cao, Yixing (author), Chen, Shanghuan (author), Li, Yutong (author), Du, Yunjia (author), Chen, Wei (author), Fan, J. (author), Zhang, Kouchi (author)The emission spectra of high color rendering phosphors, mixed with the yttrium aluminium garnet, silicon based oxynitride and nitride based phosphors, were predicted by the Lambert-Beer theory and back propagation neural network (BP NN). Firstly, the modified Lambert-Beer model was used to calculate the proportional coefficient of the...journal article 2021
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Fan, J. (author), Jing, Zhou (author), Cao, Yixing (author), Ibrahim, Mesfin Seid (author), Li, Min (author), Fan, Xuejun (author), Zhang, Kouchi (author)With their advantages of high efficiency, long lifetime, compact size and being free of mercury, ultraviolet light-emitting diodes (UV LEDs) are widely applied in disinfection and purification, photolithography, curing and biomedical devices. However, it is challenging to assess the reliability of UV LEDs based on the traditional life test or...journal article 2021
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Ibrahim, Mesfin Seid (author), Fan, J. (author), Yung, Winco K.C. (author), Jing, Zhou (author), Fan, Xuejun (author), van Driel, W.D. (author), Zhang, Kouchi (author)The increased system complexity in electronic products brings challenges in a system level reliability assessment and lifetime estimation. Traditionally, the graph model-based reliability block diagrams (RBD) and fault tree analysis (FTA) have been used to assess the reliability of products and systems. However, these methods are based on...journal article 2021
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Fan, J. (author), Li, Yutong (author), Fryc, Irena (author), Qian, C. (author), Fan, X. (author), Zhang, Kouchi (author)The full-spectrum white light-emitting diode (LED) emits light with a broad wavelength range by mixing all lights from multiple LED chips and phosphors. Thus, it has great potentials to be used in healthy lighting, high resolution displays, plant lighting with higher color rendering index close to sunlight and higher color fidelity index. The...journal article 2020
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Yazdan Mehr, M. (author), Bahrami, A. (author), van Driel, W.D. (author), Fan, X.J. (author), Davis, J.L. (author), Zhang, Kouchi (author)In this paper, degradation mechanisms of optical materials, used in the light emitting diode (LED)-based products, are reviewed. The LED lighting is one of the fastest technology shifts in human history. Lighting accounts for almost 20% of the global electrical energy use, inferring that replacement of traditional lighting sources with LEDs...journal article 2020
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Ibrahim, Mesfin Seid (author), Fan, Jiajie (author), Yung, Winco K.C. (author), Prisacaru, Alexandru (author), van Driel, W.D. (author), Fan, X. (author), Zhang, Kouchi (author)Light-emitting diodes (LEDs) are among the key innovations that have revolutionized the lighting industry, due to their versatility in applications, higher reliability, longer lifetime, and higher efficiency compared with other light sources. The demand for increased lifetime and higher reliability has attracted a significant number of...review 2020
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Sun, B. (author), Fan, J. (author), Fan, Xuejun (author), Zhang, Kouchi (author), Zhang, Guohao (author)In this paper, a physics of failure-based prediction method is combined with statistical models to consider the impact of current crowding and current droop effects on the reliability of LED arrays. Electronic-thermal models of LEDs are utilized to obtain the operation conditions under the influences of current crowding and current droop. A...journal article 2019
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Yazdan Mehr, M. (author), van Driel, W.D. (author), De Buyl, Francois (author), Zhang, Kouchi (author)Degradation mechanisms of silicone plates under harsh environment conditions are studied in this investigation. Environmental degradation of silicone free form, used as secondary optics in Light Emitting Diode LED lighting lamps and luminaires or any other applications requiring high quality optics being used, has negative implications for the...journal article 2018
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Yazdan Mehr, M. (author), Toroghinejad, M.R. (author), Karimzadeh, F. (author), van Driel, W.D. (author), Zhang, Kouchi (author)Reduction of intensity of light output is one of the most common degradation modes in light-emitting diode (LED) systems. It starts from the failure of the various components in the system, including the chip, the driver, and optical components (i.e. phosphorous layer). The kinetics of degradation in real life applications is relatively slow...journal article 2018
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Sun, Bo (author), Fan, Xuejun (author), van Driel, W.D. (author), Cui, Chengqiang (author), Zhang, Kouchi (author)In this study, we present a general methodology that combines the reliability theory with physics of failure for reliability prediction of an LED driver. More specifically, an integrated LED lamp, which includes an LED light source with statistical distribution of luminous flux, and a driver with a few critical components, is considered. The...journal article 2018
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Sun, B. (author), Fan, J. (author), Fan, Xuejun (author), Zhang, Kouchi (author)This work studies the effect of randomness of LED's lumen depreciation on reliability of the entire LED lamp. An integrated LED light bulb is selected as carrier of the proposed method. A PoF based lumen depreciation model and electronic-thermal simulations are introduced for reliability prediction. The normal distribution is used to describe...conference paper 2018
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Santagata, F. (author), Sun, J. (author), Iervolino, E. (author), Yu, H. (author), Wang, F. (author), Zhang, Kouchi (author), Sarro, Pasqualina M (author), Zhang, Guoyi (author)Purpose: The purpose of this paper is to demonstrate a novel 3D system-in-package (SiP) approach. This new packaging approach is based on stacked silicon submount technology. As demonstrators, a smart lighting module and a sensor systems were successfully developed by using the fabrication and assembly process described in this paper. Design...journal article 2018
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Sun, B (author), Fan, Xuejun (author), Zhang, Kouchi (author)This chapter investigates the reliability of the integrated LED lamps with electrolytic capacitor-less LED drivers. Firstly, the impact of the interaction between the degradations of the LED light source and the driver on the lumen depreciation is studied. The electronic-thermal simulation was carried out to obtain the history of temperatures of...book chapter 2018
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Tang, H. (author), Ye, Huai-Yu (author), Chen, Xian-Ping (author), Qian, Cheng (author), Fan, Xue-Jun (author), Zhang, Kouchi (author)In this paper, the heat transfer performance of the multi-chip (MC) LED module is investigated numerically by using a general analytical solution. The configuration of the module is optimized with genetic algorithm (GA) combined with a response surface methodology. The space between chips, the thickness of the metal core printed circuit board...journal article 2017
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