• Journal of Ceramic Processing Research
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• v.20 no.spc1
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• pp.86-91
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• 2019

A solid-state route was used to prepare sodium titanium oxide (NTO, Na2Ti3O7) as a solar heat protecting material with an impressive solar reflectance (TSR = 94.3%) using a high refractive index rutile TiO2. The solar reflectance of the synthesized NTO was measured using UV-Vis-NIR spectrophotometer. Solar reflectance property of the synthesized compound depends on the calcination temperature. The solar reflectance property of the synthesized NTO powder was compared with commercial rutile TiO2. The compound synthesized at 900 ℃ for 24 hrs had remarkable solar reflectance 94.3% than that calcined below 900 ℃. Crystalline nature, structural property, morphology and optical properties of NTO powders were characterized and analyzed using XRD, FE-SEM, EDS and UV-Vis-NIR spectrophotometer. From the results, we guessed that NTO would be a suitable "solar heat protecting candidate" for energy-saving applications in coating industries.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.251-252
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• 2018

Cool roof coating materials generally use white color which has the highest reflectance, but it is a tendency to apply various colors because it can cause glare and fatigue of a nearby building user due to the urban beauty and high reflection. This study when applying color diversity material cool roof coating was carried out as a basic research for the degree of solar radiation reflectance change. Experiment result. As a result of the measurement of the reflectance of each specimen, white showed the best reflectance in the near infrared region, and black had the lowest reflectance. Also, in case of brown, it was confirmed that the reflectance of solar radiation in the near extrinsic region is lower than that of gray.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.12
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• pp.565-571
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• 2014

Nowadays, to make buildings light weight and aesthetically pleasing, curtain wall structure are commonly used. Therefore, window to wall ratio is increasing, which has caused cooling and heating load in crease in buildings as well. This phenomenon has negative impact from energy point of view. This paper analyzes window and wall convective heat gain when the slat reflectance of external and internal blinds are changed for the better understanding of the fundamentals behind the phenomena. It was observed that, if slat reflectance is increased, window transmitted solar increases and convection heat rate is clearly affected. Among six surfaces including four walls, ceiling and floor, maximum convection heat rate occurs on the south wall in summer. On the other hand, ceiling and floor showed the lowest convection heat gain, since they are shared by adjacent floors.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.37-38
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• 2017

In Infrared rays, which are 50% of sunlight, act as heat rays to heat buildings. Solar heat paint is widely used to protect buildings from sunlight. Solar heat coatings are used to block buildings form sunlight. Solar heat paints are classified as heat-reflective paints and heat-insulating paints according to the differential thermal mechanism. In this study, we study the thermal differential mechanism by analyzing the temperature change of the coated steel plate and the solar reflection spectrum on the surface. In this experiment, exposed steel plate, heat-reflective coated steel plate, heat-insulating coated steel plate, and general paint coated steel plate were used. As a result, when the infrared rays of 780nm ~ 1400nm were irradiated, the heat reflective paint had a temperature lower by 10 degrees than other paints. Analysis of the reflection spectrum of the paint shows that the heat paint is lower in heat than other paints because it has higher reflectance of light and absorbs much of the infrared rays.

• Journal of the Korean Solar Energy Society
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• v.31 no.5
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• pp.33-40
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• 2011

In this study, it is quantitatively analyzed for thermal Characteristics of isolation-heat paint which has been supplied to a domestic market through experiments and simulations. In the case of experiment using the container box, it shows 8% decrease on cooling energy consumption in a summer season, but shows increase on heating energy consumption. As a result, the analysis has found increase of energy consumption. As a result of holding simulations with meteorological data of domestic major cities, it shows an increase of energy consumption in domestic condition, and it is hard to expect an energy saving from the isolation-heat paint unless greater air-conditioning load.

• Journal of the Semiconductor & Display Technology
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• v.18 no.4
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• pp.12-17
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• 2019

In this study, the Ag nano-dots structure and silicon nitride film were applied to the textured wafer surface to improve the light trapping effect of mono-crystalline silicon solar cell. Ag nano-dots structure was formed by performing a heat treatment for 30 minutes at 650℃ after the deposition of 10nm Ag thin film. Ag thin film deposition was performed using a thermal evaporator. The silicon nitride film was deposited by a Hot-wire chemical vapor deposition. The effect of light trapping was compared and analyzed through light reflectance measurements. Experimental results showed that the reflectivity increased by 0.5 ~ 1% under all nitride thickness conditions when Ag nano-dots structure was formed before nitride film deposition. In addition, when the Ag nano-dots structure is formed after deposition of the silicon nitride film, the reflectance is increased in the nitride film condition of 70 nm or more. When the HF treatment was performed for 60 seconds to improve the Ag nano-dot structure, the overall reflectance was improved, and the reflectance was 0.15% lower than that of the silicon nitride film-only sample at 90 nm silicon nitride film condition.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.320.1-320.1
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• 2013

We have investigated the effect of surface passivation for crystalline silicon solar cell using ozone-based atomic layer deposited (ALD) $Al_2O_3$. We examined passivation properties such as uniformity, carrier lifetime, thickness, negative fixed charge density at AlOx/Si interface, and reflectance. The influences of process temperature and heat treatment were investigated using microwave photoconductance decay (PCD). Ozone-based ALD $Al_2O_3$ film shows the best carrier lifetime at lower deposition temperature than $H_2O$-based ALD.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.177-186
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• 2011

We can expect reduction of the sunlight absorption quantity to a structure and an earth surface, a decline of the surface temperature and a decline of the heat transport volume in what there is a method I give the sunlight reflectance in the aspect to the surface of the building by painting sunlight high reflectance paint, and to reduce the sunlight absorption quantity to a structure and an earth surface and does so, and, in addition, a method high water retentivity of tree planting and the road surface of the city space uses evaporation latent heat of the water by making it, and to restrain a rise in temperature is thought about. and It is thought that I reduce the sunlight absorption quantity to not only the structure but also other structures and attention gathers to the reflexive reflector reflecting in the direction again and it is wide as a marker of a board and the clothing of the traffic sign and is used the incidence energy from a source of light for this reflexive reflector now by there is it and devises surface structure again, and controlling reflection directivity for the sunlight for the purpose of raising night visibility.

• Journal of the Semiconductor & Display Technology
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• v.11 no.3
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• pp.27-31
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• 2012

This paper presents a study on the design of photovoltaic system with reversal tracking reflector. The reversal tracking reflector is conceptually designed by using TRIZ. The 20 to 30% of incident rays cannot produce the current and reflected back to the glass surface because of high refractive index of solar cell which are produced from Si, GaAs. The solution of this problem has been derived using 6SC(6 steps creativity)TRIZ. The reflector which has the actuator can be trackback the sun. Reversal tracking reflector which mounted on the top of the system prevents the shadowing loss and improve the efficiency of track back function. The anti-glare reflector prevents the heat due to the concentrated reflected light rays.

• Journal of the Korean Solar Energy Society
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• v.35 no.2
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• pp.73-83
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• 2015

When it comes to these buildings for business use, cooling load during summertime was reported to have great importance which, as a result, impressively increased interest in Solar Heat Gain Coefficient (SHGC). Such SHGC is considered to be lowered with the help of colors and functions of glass itself, internal shading devices, insulation films and others but basically, these external shading devices for initial blocking that would not allow solar heat to come in from outside the buildings are determined to be most effective. Of many different external shading devices, this thesis conducted an analysis on Exterior Venetian Blind. As for vertical shading devices, previous researches already calculated SHGC conveniently using concepts of sky-opening ratios. However in terms of the Venetian Blind, such correlation is not possibly applied. In light of that, in order to extract a valid correlation, this study first introduced a concept called shape factor, which would use the breadth and a space of a shade, before carrying out the analysis. As a consequence, the concept helped this study to find a very similar correlation. Results of the analysis are summarized as follows. (1) Regarding SHGC depending on the surface reflectance of a shade, an average of 2% error is observed and yet, the figure can always be ignored when it comes to a simple calculation. (2) As for SHGC of each bearing, this study noticed deviations of 4% or less and in the end, it is confirmed that extraction can be achieved with no more than one correlation formula. (3) When only the shape factor and nothing else is used for finding a correlation formula, the formula with a deviation of approximately 5% or less is what one would expect. (4) Since the study observed slight differences in bearings depending on ranges of the shape factors, it needed to extract a weighted value of each bearing, and learned that the smaller the shape factor, the wider the range of a weighted value. The study now suggests that a follow-up research to extract a simple calculation formula by dealing with all these various inclined angles of shade, solar radiation conditions of each region (the ratio of diffuse radiation to direct radiation and others) as well as seasonal features should be carried out.