The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Alireza Daneshmehr - One of the best experts on this subject based on the ideXlab platform.
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low velocity impact analysis of fiber metal laminates fmls in thermal environments with various boundary conditions
Composite Structures, 2016Co-Authors: Hamed Zarei, Mohadeseh Fallah, Giangiacomo Minak, H Bisadi, Alireza DaneshmehrAbstract:Abstract This paper presents the dynamic response of Glare5-3/2 subjected to low velocity impact. Governing equations are derived based on laminate theory and Hamilton’s principle. The Hertzian contact law is employed to capture contact force history and other impact characteristics. A Ritz based approach appropriate for in-plane loads and various boundary conditions is developed. The nonlinear system of equations is solved using the fourth order Runge–Kutta method. The validity of the present model is demonstrated by good agreement of comparisons between its predictions and results in the literature. The effect of various parameters such as impactor velocity, impactor radius, boundary conditions and thermal environment are investigated in detail. In order to consider thermal environment effect, the temperature dependent material properties are taken into account. Boundary conditions and thermal environment affect the low velocity impact response of Glare, hitherto not reported in the open literature.
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low velocity impact analysis of fiber metal laminates fmls in thermal environments with various boundary conditions
Composite Structures, 2016Co-Authors: Hamed Zarei, Mohadeseh Fallah, Giangiacomo Minak, H Bisadi, Alireza DaneshmehrAbstract:Abstract This paper presents the dynamic response of Glare5-3/2 subjected to low velocity impact. Governing equations are derived based on laminate theory and Hamilton’s principle. The Hertzian contact law is employed to capture contact force history and other impact characteristics. A Ritz based approach appropriate for in-plane loads and various boundary conditions is developed. The nonlinear system of equations is solved using the fourth order Runge–Kutta method. The validity of the present model is demonstrated by good agreement of comparisons between its predictions and results in the literature. The effect of various parameters such as impactor velocity, impactor radius, boundary conditions and thermal environment are investigated in detail. In order to consider thermal environment effect, the temperature dependent material properties are taken into account. Boundary conditions and thermal environment affect the low velocity impact response of Glare, hitherto not reported in the open literature.
Wonwoo Kim - One of the best experts on this subject based on the ideXlab platform.
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A prediction method to identify the Glare source in a window with non-uniform luminance distribution
Energy and Buildings, 2012Co-Authors: Wonwoo Kim, Jeong Tai KimAbstract:Abstract A proper Glare prediction method is needed to promote visual comfort. The purpose of this study is to suggest the methodology to identify the Glare source, which is necessary in order to control Glare coming from windows. Experiments with subjects were conducted in order to evaluate discomfort Glare from windows and the features that made the subjects recognize the Glare sources in the windows with non-uniform luminance distributions were explored. Discomfort Glare was evaluated in two categories: first across the whole window and then by unit area of the window. The results of the evaluations led to the realization that the discomfort Glare value of the whole window is larger than the mean value of the discomfort Glares from the window patches. In addition, it is revealed that the evaluated value of discomfort Glare is a function of the average luminance of the visual field. There is a linear relationship between the average luminance of the visual field and the average luminance of the Glare patches. Such linear relationship has been translated into a formula, whose high accuracy is proven in the study. Using the formula makes it possible to easily identify the window patches that would generate Glare.
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The Variation of the Glare Source Luminance According to the Average Luminance of Visual Field
Indoor and Built Environment, 2011Co-Authors: Wonwoo Kim, Jeong Tai KimAbstract:This study was conducted to propose a method of identifying Glare sources from windows. Discomfort Glare from windows of a classroom was evaluated in the experiments involving subjects, and the features that made the subjects recognize the Glare sources in the windows were explored. The results of the evaluation led to the realization that the subjects regarded the patches that were causing discomfort Glare as the Glare sources on windows. It means that the patches having low luminance were not the causes of discomfort Glare and were excluded from Glare sources for the discomfort Glare evaluation. There was a linear relationship between the average luminance of the visual field and the average luminance of the Glare patches. The linear relationship has been expressed by a formula. The proposed formula has made it easier to identify the Glare patches from windows. The approach as suggested in this study is distinctive to the others by the fact that the Glare source was determined based on the average lumin...
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Effect of Background Luminance on Discomfort Glare in Relation to the Glare Source Size
Indoor and Built Environment, 2010Co-Authors: Wonwoo Kim, Jeong Tai KimAbstract:Discomfort Glare from bright luminaires or windows is not a simple matter but consists of a complex relationship between a number of factors. The objective of this study was to investigate the effect of the background luminance on discomfort Glare in relation to the size of the Glare source. An experiment was conducted with observers. In the experiment, the change in the discomfort Glare, depending on the change in the background luminance, was measured using different sizes of Glare sources. Seven sizes of steradian of the Glare source were selected and five levels of background luminance were chosen for the experiment. The results showed that the higher the background luminance, the smaller the observer’s degree of discomfort Glare. The exponent of background luminance changed clearly into different patterns in relation to the sizes of the Glare source. A new mathematical formula has been developed by this study to determine the exponent of the background luminance for use in the range from 0.0003 to 5 ...
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An Experiment of Discomfort Glare from Non-uniform Glare Source
Journal of the Korean Institute of Illuminating and Electrical Installation Engineers, 2009Co-Authors: Ju-young Shin, Jeong Tai Kim, Wonwoo KimAbstract:Impact of daylighting on the visual environment can improve occupant`s well-being by providing visual comfort. Also, daylighting can save energy. However, Glare from window can be a direct hazard to vision and can cause serious discomfort. Selecting Glare source on a window plane is very important for evaluating discomfort Glare from windows. But former Glare indices can not identify the range of the Glare source properly. In this study, difference in Glare sensation with uniform and non-uniform Glare sources are evaluated to identify the range of the Glare source. The Glare source was assumed as window model. The window was divided into three parts with different luminance values. The experiment was conducted under 1[m], 1.5[m], 3[m] distance from the Glare source. Two results were obtained from the experiments. First, the degree of discomfort Glare increased as average window luminance increased. Second, the middle and lower part of the window plane can affect evaluation of discomfort Glare as well as the upper part of the window plan. These results can be used for selecting the Glare source in a window with non-uniform luminance.
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A method for evaluating discomfort Glare from windows: Part 1. A formula for evaluating discomfort Glare from large Glare sources with uniform luminance
JOURNAL OF THE ILLUMINATING ENGINEERING INSTITUTE OF JAPAN, 2007Co-Authors: Wonwoo Kim, Yasuko Koga, Masayasu HaraAbstract:A new formula is proposed for evaluating discomfort Glare from large Glare sources with uniform luminance. The formula has four parameters: luminance of the Glare source, size of the Glare source, background luminance and position index. An experiment was conducted to investigate the effect of each parameter on the evaluation of discomfort Glare. Twenty subjects evaluated discomfort Glare from the model window. The new formula shows the relation between the degree of discomfort Glare and the parameters. The formula is distinct from other formulas in that it has a simple form and the background luminance has little effect on the degree of discomfort Glare. It is expected that discomfort Glare from large Glare sources with uniform luminance can be appraised using the formula.
Hamed Zarei - One of the best experts on this subject based on the ideXlab platform.
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low velocity impact analysis of fiber metal laminates fmls in thermal environments with various boundary conditions
Composite Structures, 2016Co-Authors: Hamed Zarei, Mohadeseh Fallah, Giangiacomo Minak, H Bisadi, Alireza DaneshmehrAbstract:Abstract This paper presents the dynamic response of Glare5-3/2 subjected to low velocity impact. Governing equations are derived based on laminate theory and Hamilton’s principle. The Hertzian contact law is employed to capture contact force history and other impact characteristics. A Ritz based approach appropriate for in-plane loads and various boundary conditions is developed. The nonlinear system of equations is solved using the fourth order Runge–Kutta method. The validity of the present model is demonstrated by good agreement of comparisons between its predictions and results in the literature. The effect of various parameters such as impactor velocity, impactor radius, boundary conditions and thermal environment are investigated in detail. In order to consider thermal environment effect, the temperature dependent material properties are taken into account. Boundary conditions and thermal environment affect the low velocity impact response of Glare, hitherto not reported in the open literature.
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low velocity impact analysis of fiber metal laminates fmls in thermal environments with various boundary conditions
Composite Structures, 2016Co-Authors: Hamed Zarei, Mohadeseh Fallah, Giangiacomo Minak, H Bisadi, Alireza DaneshmehrAbstract:Abstract This paper presents the dynamic response of Glare5-3/2 subjected to low velocity impact. Governing equations are derived based on laminate theory and Hamilton’s principle. The Hertzian contact law is employed to capture contact force history and other impact characteristics. A Ritz based approach appropriate for in-plane loads and various boundary conditions is developed. The nonlinear system of equations is solved using the fourth order Runge–Kutta method. The validity of the present model is demonstrated by good agreement of comparisons between its predictions and results in the literature. The effect of various parameters such as impactor velocity, impactor radius, boundary conditions and thermal environment are investigated in detail. In order to consider thermal environment effect, the temperature dependent material properties are taken into account. Boundary conditions and thermal environment affect the low velocity impact response of Glare, hitherto not reported in the open literature.
Jeong Tai Kim - One of the best experts on this subject based on the ideXlab platform.
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A prediction method to identify the Glare source in a window with non-uniform luminance distribution
Energy and Buildings, 2012Co-Authors: Wonwoo Kim, Jeong Tai KimAbstract:Abstract A proper Glare prediction method is needed to promote visual comfort. The purpose of this study is to suggest the methodology to identify the Glare source, which is necessary in order to control Glare coming from windows. Experiments with subjects were conducted in order to evaluate discomfort Glare from windows and the features that made the subjects recognize the Glare sources in the windows with non-uniform luminance distributions were explored. Discomfort Glare was evaluated in two categories: first across the whole window and then by unit area of the window. The results of the evaluations led to the realization that the discomfort Glare value of the whole window is larger than the mean value of the discomfort Glares from the window patches. In addition, it is revealed that the evaluated value of discomfort Glare is a function of the average luminance of the visual field. There is a linear relationship between the average luminance of the visual field and the average luminance of the Glare patches. Such linear relationship has been translated into a formula, whose high accuracy is proven in the study. Using the formula makes it possible to easily identify the window patches that would generate Glare.
-
The Variation of the Glare Source Luminance According to the Average Luminance of Visual Field
Indoor and Built Environment, 2011Co-Authors: Wonwoo Kim, Jeong Tai KimAbstract:This study was conducted to propose a method of identifying Glare sources from windows. Discomfort Glare from windows of a classroom was evaluated in the experiments involving subjects, and the features that made the subjects recognize the Glare sources in the windows were explored. The results of the evaluation led to the realization that the subjects regarded the patches that were causing discomfort Glare as the Glare sources on windows. It means that the patches having low luminance were not the causes of discomfort Glare and were excluded from Glare sources for the discomfort Glare evaluation. There was a linear relationship between the average luminance of the visual field and the average luminance of the Glare patches. The linear relationship has been expressed by a formula. The proposed formula has made it easier to identify the Glare patches from windows. The approach as suggested in this study is distinctive to the others by the fact that the Glare source was determined based on the average lumin...
-
Effect of Background Luminance on Discomfort Glare in Relation to the Glare Source Size
Indoor and Built Environment, 2010Co-Authors: Wonwoo Kim, Jeong Tai KimAbstract:Discomfort Glare from bright luminaires or windows is not a simple matter but consists of a complex relationship between a number of factors. The objective of this study was to investigate the effect of the background luminance on discomfort Glare in relation to the size of the Glare source. An experiment was conducted with observers. In the experiment, the change in the discomfort Glare, depending on the change in the background luminance, was measured using different sizes of Glare sources. Seven sizes of steradian of the Glare source were selected and five levels of background luminance were chosen for the experiment. The results showed that the higher the background luminance, the smaller the observer’s degree of discomfort Glare. The exponent of background luminance changed clearly into different patterns in relation to the sizes of the Glare source. A new mathematical formula has been developed by this study to determine the exponent of the background luminance for use in the range from 0.0003 to 5 ...
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An Experiment of Discomfort Glare from Non-uniform Glare Source
Journal of the Korean Institute of Illuminating and Electrical Installation Engineers, 2009Co-Authors: Ju-young Shin, Jeong Tai Kim, Wonwoo KimAbstract:Impact of daylighting on the visual environment can improve occupant`s well-being by providing visual comfort. Also, daylighting can save energy. However, Glare from window can be a direct hazard to vision and can cause serious discomfort. Selecting Glare source on a window plane is very important for evaluating discomfort Glare from windows. But former Glare indices can not identify the range of the Glare source properly. In this study, difference in Glare sensation with uniform and non-uniform Glare sources are evaluated to identify the range of the Glare source. The Glare source was assumed as window model. The window was divided into three parts with different luminance values. The experiment was conducted under 1[m], 1.5[m], 3[m] distance from the Glare source. Two results were obtained from the experiments. First, the degree of discomfort Glare increased as average window luminance increased. Second, the middle and lower part of the window plane can affect evaluation of discomfort Glare as well as the upper part of the window plan. These results can be used for selecting the Glare source in a window with non-uniform luminance.
Mohadeseh Fallah - One of the best experts on this subject based on the ideXlab platform.
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low velocity impact analysis of fiber metal laminates fmls in thermal environments with various boundary conditions
Composite Structures, 2016Co-Authors: Hamed Zarei, Mohadeseh Fallah, Giangiacomo Minak, H Bisadi, Alireza DaneshmehrAbstract:Abstract This paper presents the dynamic response of Glare5-3/2 subjected to low velocity impact. Governing equations are derived based on laminate theory and Hamilton’s principle. The Hertzian contact law is employed to capture contact force history and other impact characteristics. A Ritz based approach appropriate for in-plane loads and various boundary conditions is developed. The nonlinear system of equations is solved using the fourth order Runge–Kutta method. The validity of the present model is demonstrated by good agreement of comparisons between its predictions and results in the literature. The effect of various parameters such as impactor velocity, impactor radius, boundary conditions and thermal environment are investigated in detail. In order to consider thermal environment effect, the temperature dependent material properties are taken into account. Boundary conditions and thermal environment affect the low velocity impact response of Glare, hitherto not reported in the open literature.
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low velocity impact analysis of fiber metal laminates fmls in thermal environments with various boundary conditions
Composite Structures, 2016Co-Authors: Hamed Zarei, Mohadeseh Fallah, Giangiacomo Minak, H Bisadi, Alireza DaneshmehrAbstract:Abstract This paper presents the dynamic response of Glare5-3/2 subjected to low velocity impact. Governing equations are derived based on laminate theory and Hamilton’s principle. The Hertzian contact law is employed to capture contact force history and other impact characteristics. A Ritz based approach appropriate for in-plane loads and various boundary conditions is developed. The nonlinear system of equations is solved using the fourth order Runge–Kutta method. The validity of the present model is demonstrated by good agreement of comparisons between its predictions and results in the literature. The effect of various parameters such as impactor velocity, impactor radius, boundary conditions and thermal environment are investigated in detail. In order to consider thermal environment effect, the temperature dependent material properties are taken into account. Boundary conditions and thermal environment affect the low velocity impact response of Glare, hitherto not reported in the open literature.
