The Experts below are selected from a list of 2943 Experts worldwide ranked by ideXlab platform
Jong Kyu Kim - One of the best experts on this subject based on the ideXlab platform.
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efficiency droop in light emitting diodes challenges and countermeasures
Laser & Photonics Reviews, 2013Co-Authors: Jaehee Cho, Jong Kyu KimAbstract:Efficiency droop, i.e. the loss of efficiency at high operating current, afflicts nitride-based light-emitting diodes (LEDs). The droop phenomenon is currently the subject of intense research, as it retards the advancement of solid-state Lighting which is just starting to supplant fluorescent as well as Incandescent Lighting. Although the technical community does not yet have consented to a single cause of droop, this article provides a summary of the present state of droop research, reviews currently discussed droop mechanisms, and presents a recently developed theoretical model for the efficiency droop. In the theoretical model, carrier leakage out of the active region caused by the asymmetry of the pn junction, specifically the disparity between electron and hole concentrations and mobilities, is discussed in detail. The model is in agreement with the droop's key behaviors not only for GaInN LEDs but also for AlGaInP LEDs.
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Solid-state light sources getting smart
Science, 2005Co-Authors: E. Fred Schubert, Jong Kyu KimAbstract:More than a century after the introduction of Incandescent Lighting and half a century after the introduction of fluorescent Lighting, solid-state light sources are revolutionizing an increasing number of applications. Whereas the efficiency of conventional Incandescent and fluorescent lights is limited by fundamental factors that cannot be overcome, the efficiency of solid-state sources is limited only by human creativity and imagination. The high efficiency of solid-state sources already provides energy savings and environmental benefits in a number of applications. However, solid-state sources also offer controllability of their spectral power distribution, spatial distribution, color temperature, temporal modulation, and polarization properties. Such "smart" light sources can adjust to specific environments and requirements, a property that could result in tremendous benefits in Lighting, automobiles, transportation, communication, imaging, agriculture, and medicine.
Hasanah, Aas Wasri - One of the best experts on this subject based on the ideXlab platform.
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Implementasi Tenaga Matahari 60 Wp Untuk Fasilitas Umum Area Parkir Di Perum Villa Mutiara Serpong, Tangerang Selatan, Banten
'Sekolah Tinggi Teknik-PLN', 2021Co-Authors: Hasanah, Aas WasriAbstract:The existence of street Lighting and / or public facilities is very important for the convenience of residents, especially in the car park at night. However, not all of them have installed Lighting as in the land area, block B / C, stage 1, Villa Mutiara Serpong, Pondok Jagung, South Tangerang. This area is a land of public facilities whose area is still ground, and most of them have not installed lights to illuminate the entire area, because car parks also need Lighting that is important enough to monitor unwanted things, therefore it is necessary to install the Lighting of these public facilities and the road inside. this is in the form of solar powered lamps as an effective alternative for solutions in Lighting and reducing the cost of using electricity from PLN. Solar lights are installed at strategic points, namely in areas with little Lighting. The lamp used is a 60-90 watt power lamp for better Lighting. In addition to street Lighting and public facilities, an economic analysis is also carried out in this activity by comparing the total costs required between Incandescent Lighting and solar power. Where it is found that the nominal difference in rupiah is Rp.2,607,455, which is more efficient than Incandescent PJU, and solar lamps are not affected by TDL (basic electricity cost). Keywords: parking area, Public Facilities, Lights, Solar Energ
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Sun Power Implementation for Public Parking Area in Perum Villa Mutiara Serpong, Tangerang Selatan, Banten
'Universitas Negeri Jakarta', 2021Co-Authors: Nur Qosim Muchamad, Hasanah, Aas Wasri, Pujotomo Isworo, Hariyati RinnaAbstract:Keberadaan penerangan jalan dan atau fasilitas umum adalah salah satu hal yang sangat penting demi kenyamanan warga khususnya di area parkir mobil malam hari. Tetapi, tidak semuanya telah terpasang penerangan seperti halnya di area lapangan tanah, blok B/C tahap 1, Villa Mutiara Serpong, Pondok Jagung, Tangerang Selatan. Area ini merupakan lahan Fasum yang areanya masih tanah, dan sebagian besar belum terpasang lampu untuk penerangan seluruh areanya, karena parkir mobil juga membutuhkan pencahayaan yang cukup penting untuk memantau hal yang tidak diinginkan, oleh karena itu diperlukan pemasangan penerangan fasilitas umum tersebut dan jalan dalam hal ini berupa lampu tenaga surya sebagai alternatif efektif untuk solusi dalam penerangan dan pengurangan biaya pemakaian energi listrik dari PLN. Lampu tenaga surya di pasang di titik strategis yaitu di area yang sedikit pencahayaannya. Lampu yang digunakan adalah lampu daya 60-90 watt guna lebih terang lebih bagus. Selain untuk penerangan jalan dan fasilitas umum, analisis ekonomi juga dilakukan pada kegiatan ini dengan cara membandingkan total biaya yang diperlukan antara penerangan lampu pijar dengan tenaga surya. Dimana didapat selisih nominal dalam rupiah Rp 2.607.455 lebih efisien dari PJU lampu pijar, dan lampu tenaga surya tidak dipengaruhi oleh TDL (tarif dasar listrik).The existence of street Lighting and / or public facilities is very important for the convenience of residents, especially in the car park at night. However, not all of them have installed Lighting as in the land area, block B / C, stage 1, Villa Mutiara Serpong, Pondok Jagung, South Tangerang. This area is a land of public facilities whose area is still ground, and most of them have not installed lights to illuminate the entire area, because car parks also need Lighting that is important enough to monitor unwanted things, therefore it is necessary to install the Lighting of these public facilities and the road inside. this is in the form of solar powered lamps as an effective alternative for solutions in Lighting and reducing the cost of using electricity from PLN. Solar lights are installed at strategic points, namely in areas with little Lighting. The lamp used is a 60-90 watt power lamp for better Lighting. In addition to street Lighting and public facilities, an economic analysis is also carried out in this activity by comparing the total costs required between Incandescent Lighting and solar power. Where it is found that the nominal difference in rupiah is Rp.2,607,455, which is more efficient than Incandescent PJU, and solar lamps are not affected by TDL (basic electricity cost)
Jaehee Cho - One of the best experts on this subject based on the ideXlab platform.
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Efficiency droop in light-emitting diodes: Challenges and countermeasures
'Wiley', 2018Co-Authors: Jaehee Cho, Fred E. Schubert, Jk KimAbstract:Efficiency droop, i.e. the loss of efficiency at high operating current, afflicts nitride-based light-emitting diodes (LEDs). The droop phenomenon is currently the subject of intense research, as it retards the advancement of solid-state Lighting which is just starting to supplant fluorescent as well as Incandescent Lighting. Although the technical community does not yet have consented to a single cause of droop, this article provides a summary of the present state of droop research, reviews currently discussed droop mechanisms, and presents a recently developed theoretical model for the efficiency droop. In the theoretical model, carrier leakage out of the active region caused by the asymmetry of the pn junction, specifically the disparity between electron and hole concentrations and mobilities, is discussed in detail. The model is in agreement with the droop's key behaviors not only for GaInN LEDs but also for AlGaInP LEDs.X11180166sciescopu
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efficiency droop in light emitting diodes challenges and countermeasures
Laser & Photonics Reviews, 2013Co-Authors: Jaehee Cho, Jong Kyu KimAbstract:Efficiency droop, i.e. the loss of efficiency at high operating current, afflicts nitride-based light-emitting diodes (LEDs). The droop phenomenon is currently the subject of intense research, as it retards the advancement of solid-state Lighting which is just starting to supplant fluorescent as well as Incandescent Lighting. Although the technical community does not yet have consented to a single cause of droop, this article provides a summary of the present state of droop research, reviews currently discussed droop mechanisms, and presents a recently developed theoretical model for the efficiency droop. In the theoretical model, carrier leakage out of the active region caused by the asymmetry of the pn junction, specifically the disparity between electron and hole concentrations and mobilities, is discussed in detail. The model is in agreement with the droop's key behaviors not only for GaInN LEDs but also for AlGaInP LEDs.
Richard A Stone - One of the best experts on this subject based on the ideXlab platform.
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Anatomy and Pathology/Oncology Development of Experimental Myopia in Chicks in a Natural Environment
2020Co-Authors: Yuval Cohen, Alice M Mcglinn, Susan Casavant, James Shaffer, Tejvir S Khurana, Machelle T Pardue, Sherrill Davison, Michael P Iuvone, Richard A StoneAbstract:PURPOSE. The hypothesis that outdoor exposure might protect against myopia has generated much interest, although available data find only modest clinical efficacy. We tested the effect of outdoor rearing on form-deprivation myopia in chicks, a myopia model markedly inhibited by high-intensity indoor laboratory Lighting. METHODS. Unilaterally goggled cohorts of White Leghorn chicks were maintained in a speciesappropriate, outdoor rural setting during daylight hours to the extent permitted by weather. Control chicks were reared indoors with Incandescent Lighting. Besides ocular refraction and ultrasound, we determined dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) content in retina and vitreous and measured mRNA expression levels of selected clock and circadian rhythm-related genes in the retina/RPE. RESULTS. Myopia developed in the goggled eyes of all cohorts. Whereas outdoor rearing lessened myopia by 44% at 4 days, a protective effect was no longer evident at 11 days. Outdoor rearing had no consistent effect on retinal or vitreous content of dopamine or DOPAC. Conforming to prior data on form-deprivation myopia, retina and vitreous levels of DOPAC were reduced in goggled eyes. Compared with contralateral eyes, the retinal expression of clock and circadian rhythm-related genes was modestly altered in myopic eyes of chicks reared indoors or outdoors. CONCLUSIONS. Outdoor rearing of chicks induces only a partial decrease of goggle-induced myopia that is not maintained, without evidence that retinal dopamine metabolism accounts for the partial myopia inhibition under these outdoor conditions. Although modest, alterations in retinal gene expression suggest that studying circadian signals might be informative for understanding refractive mechanisms
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development of experimental myopia in chicks in a natural environment
Investigative Ophthalmology & Visual Science, 2016Co-Authors: Richard A Stone, Yuval Cohen, Alice M Mcglinn, Sherill Davison, Susan Casavant, James Shaffer, Tejvir S Khurana, Machelle T Pardue, P M IuvoneAbstract:PURPOSE The hypothesis that outdoor exposure might protect against myopia has generated much interest, although available data find only modest clinical efficacy. We tested the effect of outdoor rearing on form-deprivation myopia in chicks, a myopia model markedly inhibited by high-intensity indoor laboratory Lighting. METHODS Unilaterally goggled cohorts of White Leghorn chicks were maintained in a species-appropriate, outdoor rural setting during daylight hours to the extent permitted by weather. Control chicks were reared indoors with Incandescent Lighting. Besides ocular refraction and ultrasound, we determined dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) content in retina and vitreous and measured mRNA expression levels of selected clock and circadian rhythm-related genes in the retina/RPE. RESULTS Myopia developed in the goggled eyes of all cohorts. Whereas outdoor rearing lessened myopia by 44% at 4 days, a protective effect was no longer evident at 11 days. Outdoor rearing had no consistent effect on retinal or vitreous content of dopamine or DOPAC. Conforming to prior data on form-deprivation myopia, retina and vitreous levels of DOPAC were reduced in goggled eyes. Compared with contralateral eyes, the retinal expression of clock and circadian rhythm-related genes was modestly altered in myopic eyes of chicks reared indoors or outdoors. CONCLUSIONS Outdoor rearing of chicks induces only a partial decrease of goggle-induced myopia that is not maintained, without evidence that retinal dopamine metabolism accounts for the partial myopia inhibition under these outdoor conditions. Although modest, alterations in retinal gene expression suggest that studying circadian signals might be informative for understanding refractive mechanisms.
Hariyati Rinna - One of the best experts on this subject based on the ideXlab platform.
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Sun Power Implementation for Public Parking Area in Perum Villa Mutiara Serpong, Tangerang Selatan, Banten
'Universitas Negeri Jakarta', 2021Co-Authors: Nur Qosim Muchamad, Hasanah, Aas Wasri, Pujotomo Isworo, Hariyati RinnaAbstract:Keberadaan penerangan jalan dan atau fasilitas umum adalah salah satu hal yang sangat penting demi kenyamanan warga khususnya di area parkir mobil malam hari. Tetapi, tidak semuanya telah terpasang penerangan seperti halnya di area lapangan tanah, blok B/C tahap 1, Villa Mutiara Serpong, Pondok Jagung, Tangerang Selatan. Area ini merupakan lahan Fasum yang areanya masih tanah, dan sebagian besar belum terpasang lampu untuk penerangan seluruh areanya, karena parkir mobil juga membutuhkan pencahayaan yang cukup penting untuk memantau hal yang tidak diinginkan, oleh karena itu diperlukan pemasangan penerangan fasilitas umum tersebut dan jalan dalam hal ini berupa lampu tenaga surya sebagai alternatif efektif untuk solusi dalam penerangan dan pengurangan biaya pemakaian energi listrik dari PLN. Lampu tenaga surya di pasang di titik strategis yaitu di area yang sedikit pencahayaannya. Lampu yang digunakan adalah lampu daya 60-90 watt guna lebih terang lebih bagus. Selain untuk penerangan jalan dan fasilitas umum, analisis ekonomi juga dilakukan pada kegiatan ini dengan cara membandingkan total biaya yang diperlukan antara penerangan lampu pijar dengan tenaga surya. Dimana didapat selisih nominal dalam rupiah Rp 2.607.455 lebih efisien dari PJU lampu pijar, dan lampu tenaga surya tidak dipengaruhi oleh TDL (tarif dasar listrik).The existence of street Lighting and / or public facilities is very important for the convenience of residents, especially in the car park at night. However, not all of them have installed Lighting as in the land area, block B / C, stage 1, Villa Mutiara Serpong, Pondok Jagung, South Tangerang. This area is a land of public facilities whose area is still ground, and most of them have not installed lights to illuminate the entire area, because car parks also need Lighting that is important enough to monitor unwanted things, therefore it is necessary to install the Lighting of these public facilities and the road inside. this is in the form of solar powered lamps as an effective alternative for solutions in Lighting and reducing the cost of using electricity from PLN. Solar lights are installed at strategic points, namely in areas with little Lighting. The lamp used is a 60-90 watt power lamp for better Lighting. In addition to street Lighting and public facilities, an economic analysis is also carried out in this activity by comparing the total costs required between Incandescent Lighting and solar power. Where it is found that the nominal difference in rupiah is Rp.2,607,455, which is more efficient than Incandescent PJU, and solar lamps are not affected by TDL (basic electricity cost)
