The Experts below are selected from a list of 4488 Experts worldwide ranked by ideXlab platform
Yoon Hyoung Cho - One of the best experts on this subject based on the ideXlab platform.
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A high‐Luminous‐Efficacy PDP having multi‐anodes for reduction of ionic effect (MARI)
Journal of The Society for Information Display, 2005Co-Authors: Joon Yeon Kim, Tae-woo Kim, Jeong-nam Kim, Hak-cheol Yang, Yoon Hyoung ChoAbstract:— We propose a PDP having a new structure and driving scheme. An auxiliary electrode was inserted between X and Y electrodes. Driving and discharge stability was determined using a test panel. A 42-in. SD (852 × 480) panel and a 42-in. HD (1366 × 768) panel were also made having this new structure, and we verified the increase in Luminous Efficacy and the reduction of ionic losses. We achieved a Luminous Efficacy of 2.35 lm/W in an SD panel and 1.97 lm/W in a HD panel. Finally, we investigated the characteristics and merits of the new structure.
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P-82: Expectation of Luminous Efficacy of Ultra Fine Discharge Cells Using 2D-Simulator
SID Symposium Digest of Technical Papers, 2005Co-Authors: Tae‐ho Lee, Minsun Yoo, Su‐bin Song, Jun Yong Park, Yoon Hyoung ChoAbstract:It has been suggested that a 50-inch full HD class is the most ideal display device for digital broadcasting. One of the problems accompanied by the decrease of cell size is the reduction of Luminous Efficacy. This paper discusses difficulty of designing fine discharge cells and the influence of cell size reduction on the Luminous Efficacy is investigated using 2-dimensional simulation. The calculated results are verified by the experimental data obtained from 6-inch test panels with various pitches. It is found that in ultra fine discharge cells the Luminous Efficacy can be enhanced adopting high xenon operation along with high frequency driving.
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26.2: A New Structure and Driving Scheme for High Luminous Efficacy in WXGA PDPs
SID Symposium Digest of Technical Papers, 2005Co-Authors: Joon Yeon Kim, Tae-woo Kim, Sung Chun Cho, Byoung Min Chun, Jeong-nam Kim, Hak-cheol Yang, Min Hur, Hyun Gu Heo, Yoon Hyoung ChoAbstract:We have proposed a new PDP cell structure called MARI (Multi Anode for Reduction of Ionic effect) together with a new driving scheme for it and achieved a high Luminous Efficacy. In the MARI PDP, a middle electrode is inserted between the X and Y sustain electrodes and the reset and scan waveforms are applied to it while the sustain pulses are applied to X and Y electrodes. Using a long gap discharge with a help of middle electrode, a high Luminous Efficacy of 1.97 lm/W has been attained in a 42-inch WXGA (1366×768) level.
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65 4 improvement in Luminous Efficacy of ultra fine discharge cells for 50 in full hd plasma tv
SID Symposium Digest of Technical Papers, 2005Co-Authors: Moonhyun Yoo, Euichul Hwang, Hyeaweon Shin, Duckhyung Lee, Yoon Hyoung ChoAbstract:In order to develop ultra-fine discharge cells with high Luminous Efficacy, several efforts have been made. We designed cell structures for the image element pitch of 0.58 mm. Both HEXA and MARI structures were considered. As for Luminous Efficacy, in constructing a 50-inch full HD PDP, we set a challenging goal to 2.0 lm/W. We believe high speed sustaining in high Xe content can help, because this is not restricted to small cell area. In addition, we developed ultra fine barrier fabrication method using sandblasting with 30 μm in width. This may contribute to improve Efficacy further by enlarging discharge space.
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A new structure and driving scheme of PDP for high Luminous Efficacy
Journal of information display, 2004Co-Authors: Joon Yeon Kim, Su Yong Chae, Tae-woo Kim, Sung Chun Cho, Byoung Min Chun, Jeong-nam Kim, Yoon Hyoung ChoAbstract:Abstract We have developed a new PDP cell structure called MARI(Multi Anode for Reduction of Ionic effect) and new driving scheme achieving a high Luminous Efficacy. The MARI PDP has middle electrode inserted between X and Y main electrodes. In the MARI PDP, reset and scan voltage is applied to middle electrode and sustain voltage is applied to X and Y electrode. Using a long gap sustain discharge we accomplished a high Luminous Efficacy. And we developed 42"full panel adopting MARI structure and new driving scheme and attained Luminous Efficacy of 2.35 lm/W.
Alfonso Soler - One of the best experts on this subject based on the ideXlab platform.
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Modelling the Luminous Efficacy of Solar Radiation
World Renewable Energy Congress VI, 2007Co-Authors: Enrique Ruiz, Alfonso Soler, L. M. RobledoAbstract:Publisher Summary Knowledge of the Luminous flux incident on a external surface is necessary for different purposes such as to estimate daylight levels indoors, to obtain cumulative illuminance distributions to quantify energy savings with the adequate use of photoelectric controls, and to evaluate daylighting systems. The ratio between illuminance and irradiance is known as the Luminous Efficacy of solar radiation. The global and diffuse Luminous Efficacy models proposed in Muneer and Kinghorn are tested with experimental data obtained at Madrid. When the models with local coefficients are statistically assessed with local data, global illuminance Lg is estimated with an acceptable accuracy but diffuse illuminance Ld is overestimated for Ld higher than about 25 klux.
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A simple clear skies model for the Luminous Efficacy of diffuse solar radiation on inclined surfaces
Renewable Energy, 2002Co-Authors: L. M. Robledo, Alfonso SolerAbstract:In the present work we study the Luminous Efficacy of diffuse solar radiation incident on vertical surfaces for a clear sky and mean hourly values of diffuse irradiance and diffuse illuminance. We develop a model easy to use, similar to a model previously obtained for horizontal surfaces. To develop the present model for vertical surfaces we assume that the slope of the surface influences diffuse illuminance and diffuse irradiance in the same way. As a consequence of this hypothesis, the Luminous Efficacy of diffuse solar radiation is assumed to be the same for both horizontal and inclined surfaces.
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Modeling the Luminous Efficacy of diffuse solar radiation on inclined surfaces for all sky conditions
Energy Conversion and Management, 2002Co-Authors: L. M. Robledo, Alfonso SolerAbstract:Abstract In the present work, we have undertaken a study of the Luminous Efficacy of diffuse solar radiation incident on vertical surfaces facing north, east, south and west for all sky conditions and mean hourly values of diffuse irradiance and diffuse illuminance. We have developed Luminous Efficacy models, of the type previously obtained for a horizontal surface, assuming that the surface slope will qualitatively influence illuminance and irradiance in the same way. Taking into account that the models obtained show that there is little variation of the Luminous Efficacy with the independent variables, an approximation to these models has been proposed that considers a constant value for the Luminous Efficacy of diffuse solar radiation. Statistical assessment shows that this approximation offers reasonable results for north, east and west vertical surfaces. When statistical assessment of the models is performed, it is observed that the values of the statistical indicators largely depend on the possibility for the surface to “see” the solar disk, as determined from geometrical considerations. For both types of models, better values of the statistical indicators are obtained when the surface sees the solar disk than when it does not.
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assessment of muneer s Luminous Efficacy models in madrid and a proposal for new models based on his approach
Journal of Solar Energy Engineering-transactions of The Asme, 2001Co-Authors: Enrique Ruiz, Alfonso Soler, L. M. RobledoAbstract:From Luminous Efficacy models, illuminance can be estimated if irradiance is known or can be estimated. In the present paper, Muneer's models for the Luminous Efficacy of global and diffuse radiation, useful for illumination engineers, are statistically assessed using data obtained at Madrid during a seven-year period. Several other models inspired on the simple approach proposed by Muneer are developed and statistically assessed. Some of those model the Luminous Efficacy of global or diffuse solar radiation, while others directly model the global or the diffuse illuminance. It is shown that for diffuse illuminance estimation the ratio of diffuse to extraterrestrial irradiance is to be preferred as independent variable to the ratio of global to extraterrestrial irradiance proposed by Muneer. Some models that estimate global illuminance from global irradiance and solar elevation, or diffuse illuminance from diffuse irradiance and solar elevation, perform practically on a par with the corresponding Luminous Efficacy models. It is also concluded that the striking difference between global Luminous Efficacy between the United Kingdom and Japan observed by Muneer is not due to a latitude effect.
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On the Luminous Efficacy of diffuse solar radiation
Energy Conversion and Management, 2001Co-Authors: L. M. Robledo, Alfonso SolerAbstract:Abstract Models for diffuse illuminance and irradiance and for the Luminous Efficacy of diffuse solar radiation are developed, specifically for clear skies, and also for all sky types. All Luminous Efficacy models reported in the present work have the distinctive feature of being obtained from empirical models developed for diffuse illuminance and irradiance, looking in this way, apparently for the first time, for a mathematical coherence between the Luminous Efficacy and the two magnitudes that define it. Statistical assessment of all the models shows that those for all sky types developed from two independent variables, solar elevation and brightness index, predict the illuminance for clear skies better than the specific clear skies models developed with solar elevation as the only independent variable.
L. M. Robledo - One of the best experts on this subject based on the ideXlab platform.
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Modelling the Luminous Efficacy of Solar Radiation
World Renewable Energy Congress VI, 2007Co-Authors: Enrique Ruiz, Alfonso Soler, L. M. RobledoAbstract:Publisher Summary Knowledge of the Luminous flux incident on a external surface is necessary for different purposes such as to estimate daylight levels indoors, to obtain cumulative illuminance distributions to quantify energy savings with the adequate use of photoelectric controls, and to evaluate daylighting systems. The ratio between illuminance and irradiance is known as the Luminous Efficacy of solar radiation. The global and diffuse Luminous Efficacy models proposed in Muneer and Kinghorn are tested with experimental data obtained at Madrid. When the models with local coefficients are statistically assessed with local data, global illuminance Lg is estimated with an acceptable accuracy but diffuse illuminance Ld is overestimated for Ld higher than about 25 klux.
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Testing diffuse Luminous Efficacy models for Florianópolis, Brazil
Building and Environment, 2004Co-Authors: Roberta Vieira Gonçalves De Souza, L. M. RobledoAbstract:Abstract This work comprises two parts. The first part presents an evaluation of diverse Luminous Efficacy models of the solar diffuse radiation available in the international scientific literature. These models were used for the estimation of the Luminous diffuse illuminance in Florianopolis, Brazil. This evaluation has taken into consideration not only the precision of the models but also the justification of the physical behavior of the Luminous Efficacy. The second part of this study presents the evaluation of the three specific diffuse Luminous Efficacy models developed for clear sky conditions, also available in the international literature. It also presents a new model that is reported for the first time in the present work. These models have not shown clear statistical balance differences among each other when estimating the diffuse illuminance, and except for one, all the studied models can perfectly explain the behavior of the diffuse Luminous Efficacy against the solar altitude. Furthermore, the evaluation has shown that the models specifically developed for clear skies show no better results than the general all sky models, analyzed in the first part of this work, when estimating the clear sky diffuse illuminance with them. These latter specific models do not show better results in the estimation of the diffuse illuminance for the clear sky conditions, than the ones obtained with some of the general models, analyzed in the first part of this work.
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A simple clear skies model for the Luminous Efficacy of diffuse solar radiation on inclined surfaces
Renewable Energy, 2002Co-Authors: L. M. Robledo, Alfonso SolerAbstract:In the present work we study the Luminous Efficacy of diffuse solar radiation incident on vertical surfaces for a clear sky and mean hourly values of diffuse irradiance and diffuse illuminance. We develop a model easy to use, similar to a model previously obtained for horizontal surfaces. To develop the present model for vertical surfaces we assume that the slope of the surface influences diffuse illuminance and diffuse irradiance in the same way. As a consequence of this hypothesis, the Luminous Efficacy of diffuse solar radiation is assumed to be the same for both horizontal and inclined surfaces.
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Modeling the Luminous Efficacy of diffuse solar radiation on inclined surfaces for all sky conditions
Energy Conversion and Management, 2002Co-Authors: L. M. Robledo, Alfonso SolerAbstract:Abstract In the present work, we have undertaken a study of the Luminous Efficacy of diffuse solar radiation incident on vertical surfaces facing north, east, south and west for all sky conditions and mean hourly values of diffuse irradiance and diffuse illuminance. We have developed Luminous Efficacy models, of the type previously obtained for a horizontal surface, assuming that the surface slope will qualitatively influence illuminance and irradiance in the same way. Taking into account that the models obtained show that there is little variation of the Luminous Efficacy with the independent variables, an approximation to these models has been proposed that considers a constant value for the Luminous Efficacy of diffuse solar radiation. Statistical assessment shows that this approximation offers reasonable results for north, east and west vertical surfaces. When statistical assessment of the models is performed, it is observed that the values of the statistical indicators largely depend on the possibility for the surface to “see” the solar disk, as determined from geometrical considerations. For both types of models, better values of the statistical indicators are obtained when the surface sees the solar disk than when it does not.
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assessment of muneer s Luminous Efficacy models in madrid and a proposal for new models based on his approach
Journal of Solar Energy Engineering-transactions of The Asme, 2001Co-Authors: Enrique Ruiz, Alfonso Soler, L. M. RobledoAbstract:From Luminous Efficacy models, illuminance can be estimated if irradiance is known or can be estimated. In the present paper, Muneer's models for the Luminous Efficacy of global and diffuse radiation, useful for illumination engineers, are statistically assessed using data obtained at Madrid during a seven-year period. Several other models inspired on the simple approach proposed by Muneer are developed and statistically assessed. Some of those model the Luminous Efficacy of global or diffuse solar radiation, while others directly model the global or the diffuse illuminance. It is shown that for diffuse illuminance estimation the ratio of diffuse to extraterrestrial irradiance is to be preferred as independent variable to the ratio of global to extraterrestrial irradiance proposed by Muneer. Some models that estimate global illuminance from global irradiance and solar elevation, or diffuse illuminance from diffuse irradiance and solar elevation, perform practically on a par with the corresponding Luminous Efficacy models. It is also concluded that the striking difference between global Luminous Efficacy between the United Kingdom and Japan observed by Muneer is not due to a latitude effect.
Kyung Cheol Choi - One of the best experts on this subject based on the ideXlab platform.
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Study on Pulse Waveforms for Improving Voltage Margin and Luminous Efficacy in an AC Plasma Display Panel Having Auxiliary Electrodes
IEEE Transactions on Electron Devices, 2010Co-Authors: Chung Sock Choi, Cheol Jang, Kyung Cheol ChoiAbstract:New pulse waveforms applied to an alternating-current plasma display panel (ac PDP) with an auxiliary electrode are investigated for the purpose of improving the panel's operating voltage margin and Luminous Efficacy. In the proposed pulse waveforms with reciprocal sustain pulses, a pair of positive and negative sustain pulses is applied to the sustain electrodes simultaneously and alternately. A positive auxiliary pulse is applied to the auxiliary electrode immediately after reciprocal sustain pulses. The voltage margin becomes wider, and the Luminous Efficacy is improved because of the suppression of the discharge toward the address electrode. In the another proposed pulse waveforms with reciprocal sustain and auxiliary pulses, a negative pulse, which is the same as the negative pulse of reciprocal sustain pulses, is additionally applied to the auxiliary electrode when reciprocal sustain pulses are applied. This negative auxiliary pulse can maintain a high level of Luminous Efficacy because it supports the effect of the auxiliary pulses. The measurement results show that the operating voltage margin is about twice wider than that of the typical pulse waveforms for an ac PDP with an auxiliary electrode; furthermore, the maximum Luminous Efficacy is able to reach 3.14 lm/W in terms of the measurement of the discharge in a 50-in XGA resolution (0.27 mm × 0.81 mm) panel with a white cell and a gas mixture of Ne+20%Xe.
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AC Microplasma Device With a Cylindrical Hollow Electrode for Improving Luminous Efficacy
IEEE Transactions on Electron Devices, 2009Co-Authors: Jeong Hun Mun, Seung Hun Kim, Kyung Cheol ChoiAbstract:In this paper, a device utilizing the hollow cathode discharge is demonstrated to diagnose the possibility of improving Luminous Efficacy of a microplasma device. A series of experiments is conducted by measuring Luminous Efficacy, which is an important factor in display devices, in accordance with specifications of the cylindrical hollow and gas pressure. The proposed structure has two electrodes, and one of them contained a cylindrical hole and is called a hollow electrode. The hollow electrode works as either a cathode or an anode alternately due to the ac operating conditions. When the hollow electrode operated as a cathode, the Luminous Efficacy is higher than that of the anode case, and this tendency is observed consistently throughout all experiments. Moreover, from the measurement results on the tendency of Luminous Efficacy in terms of hole specifications, different aspects of Luminous Efficacy are obtained, depending on whether the variation is in the diameter or in the depth. In case of the diameter, the Luminous Efficacy is improved when p middotD (i.e., the product of the gas pressure and the diameter of the cylindrical hole) is less than one Torr ldr cm. In the case of the depth, the maximum value of Luminous Efficacy exists at the certain p middotd (i.e., the product of the gas pressure and the depth of the cylindrical hole).
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P‐129: The Effect of Front Dielectric Thickness on Luminous Efficacy in AC PDP with Auxiliary Electrode
SID Symposium Digest of Technical Papers, 2008Co-Authors: Kwan Hyun Cho, Chung Sock Choi, Sung-min Lee, Kyung Cheol ChoiAbstract:The dependence of front dielectric thickness on input power density, luminance, and Luminous Efficacy according to the voltage of the auxiliary pulse in an AC PDP with an auxiliary electrode was investigated. It was found that two important factors influencing the Luminous Efficacy due to variation of the front dielectric thickness. One is the range of the voltage of the auxiliary pulse within which the power density decreases, but the luminance slightly increases, which improve the Luminous Efficacy. The other is the transmittance reducing the luminance as front dielectric thickness increased, leading to a decrease in the Luminous Efficacy. In this work, considering these two factors, the Luminous Efficacy is maximized at a front dielectric layer thickness of 40μm.
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P‐134: Dependency of Auxiliary Pulse Width on Luminous Efficacy in AC Plasma Display Panel
SID Symposium Digest of Technical Papers, 2008Co-Authors: Sung-min Lee, Chung Sock Choi, Kyung Cheol Choi, Kwan Hyun Cho, Woo-tae Kim, Jong Rae Lim, Young Jae Cho, Sung-tae KimAbstract:The width of the pulse applied to an auxiliary electrode was varied to investigate the characteristics of Luminous Efficacy of an AC plasma display with an auxiliary electrode in accordance with the frequency and duty factor of the sustain pulse. The auxiliary voltage margin increased with an increase in the sustain pulse width and a decrease in the auxiliary pulse width. In addition, the Luminous Efficacy increased with a decrease in the sustain pulse width and an increase in the auxiliary pulse width, except when the time interval between the auxiliary pulse and the subsequent sustain pulse is zero.
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A New AC Plasma Display Panel With Auxiliary Electrode for High Luminous Efficacy
IEEE Transactions on Electron Devices, 2007Co-Authors: Kyung Cheol Choi, Nam Hoon Shin, Sang Cheol Song, Sang Dae ParkAbstract:A new ac plasma display panel (PDP) for high Luminous Efficacy is proposed, and its characteristics are investigated. The new ac PDP has a coplanar gap of 200 mum and an auxiliary electrode located between the scan and common electrodes. The periodic pulses are applied to the auxiliary electrode during the sustain period, which plays the roles of enhancing the infrared emission and reducing the discharge current. The sustain voltage decreases with the increase of the auxiliary pulse voltage until 80 V. When the voltage of the pulse applied to the auxiliary electrode is 50 V, the Luminous Efficacy reaches its peak value and is approximately 8.7 lm/W obtained from the measurement of Ne + 20% Xe gas-mixture discharges in the green cells. The Luminous Efficacy of the new proposed test ac PDP with Ne + 13% Xe and Ne + 20% Xe gas mixtures is improved by 190% and 320%, respectively, compared to that of the conventional ac PDP with a Ne + 13% Xe gas mixture
Ki Woong Whang - One of the best experts on this subject based on the ideXlab platform.
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Application of MgCaO Cathode Layer to Plasma Display Panel for High Luminous Efficacy
IEEE Transactions on Electron Devices, 2013Co-Authors: Taeho Lee, Hee-woon Cheong, Ohyung Kwon, Ki Woong WhangAbstract:We have studied the characteristics of the application of a high-gamma cathode material to a plasma display panel (PDP) for the improvement of the secondary electron emission property and consequent Luminous Efficacy. It had been found that the PDP with the MgCaO cathode layer and the SiO2 diffusion barrier, which can block the impurity diffusion from the underlying dielectric layer, is stable during the normal fabrication process and showed improved Luminous Efficacy at a lower sustain voltage compared with those of the conventional PDP with MgO.
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49 1 invited paper high Luminous Efficacy and low driving voltage discharges in pdp with sro mgo double protecting layer
SID Symposium Digest of Technical Papers, 2010Co-Authors: Ki Woong Whang, Taeho Lee, Hee-woon CheongAbstract:A double protecting layer composed of MgO layer deposited on top of the SrO prevents SrO from the contamination by air and as a result, low driving voltage and high Luminous Efficacy PDP can be realized albeit a much prolong aging time is required. We adopted a special process to reduce the long aging time for the PDP with SrO-MgO double protective layer and confirmed that it can be comparable to that of the single MgO layer. The panel showed much improved Luminous Efficacy at reduced voltages.
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A New PDP Cell Structure for High Luminous Efficacy With Low-Voltage Driving
IEEE Transactions on Plasma Science, 2010Co-Authors: Hae-yoon Jung, Ki Woong WhangAbstract:We propose a new plasma display panel cell structure, called the dual ignition discharge electrodes (DIDE) structure, with a long electrode gap to realize high Luminous Efficacy. The proposed DIDE structure has a long electrode gap (200 ¿m ~ 400 ¿m) but can nevertheless be driven at relatively low voltage because of auxiliary electrodes that are formed on the front panel. The discharge characteristic of the DIDE structure is much different from the characteristic of the conventional structure, and it was analyzed through infrared emission images that are taken by an intensified charge-coupled device camera and discharge current waveforms. These studies explain the unique discharge characteristics of the DIDE structure, which originate in the ignition discharge that is generated by its own electrode structure and driving waveform. The proposed long electrode gap and low voltage effect of the DIDE structure resulted in a very high Luminous Efficacy of 7.5 lm/W in a monochrome green test with Ne-Xe (12%) mixture at 400 torr.
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Improvement of Luminance and Luminous Efficacy of Mercury-Free, Flat Fluorescent Lamp by Optimizing Phosphor Profile
IEEE Transactions on Plasma Science, 2010Co-Authors: Jae-chul Jung, Byung Joo Oh, Ki Woong WhangAbstract:A highly efficient mercury-free fluorescent lamp (MFFL) was developed for an alternative to fluorescent lamps containing mercury. The lamp has a simple structure with two main electrodes running parallel to each other and an auxiliary electrode. In order to improve the luminance and Luminous Efficacy of MFFLs further, we optimized the thickness of rear and front phosphors on the inner surfaces of the lamp, and then adopted an uneven distribution profile for the rear phosphor to increase the surface area of the phosphor. The MFFL with the optimized phosphor profile showed a wide luminance range from 3315 to 17133 cd/m2 with the corresponding Luminous Efficacy from 75.2 to 42.5 lm/W with the color coordinate around (0.32, 0.32) for daylight.
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The effect of self-erase discharge on the Luminous Efficacy of alternating current plasma display panels
Journal of Applied Physics, 2009Co-Authors: Tae Jun Kim, Hae-yoon Jung, Joong Kyun Kim, Jae-chul Jung, Ki Woong WhangAbstract:In this work, we studied the effect of self-erase discharge on the Luminous Efficacy of alternating current plasma display panels. Through discharge current analysis, we observed that self-erase discharge occurred mainly between the sustain cathode and the address electrode, which has an influence on the Luminous Efficacy. We varied the amount and timing of the self-erase discharge in order to observe the effects on the Luminous Efficacy. We found that the Luminous Efficacy could be improved by a self-erase discharge when adjusted to occur right before the main discharge in the small gap structure. In the long gap structure, on the contrary, we could increase the Luminous Efficacy when we suppressed the self-erase discharge. In addition, we suggest various waveforms to control self-erase discharge as a result of our panel experiments.
