• Solar Energy
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• v.17 no.4
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• pp.35-43
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• 1997

An increase in the design of commercial buildings with daylighting is beginning to receive more attention, claimed by some as a second revolution in architecture. The benefits of daylighting may vary significantly because a characteristic of daylight is the way in which it varies. Indirect sunlight, however, received in the interior of a building after reflection, can serve a useful purpose as the main source of illumination. In a cloudy climate it can serve as an occasional welcome addition to the available skylight. Also, site constraints or surrounding urban context may necessitate using reflected light sources, or such sources may be an integral part of the overall design objectives and aesthetics of the proposed projects. When reflected sunlight is introduced into a space, its role in general illumination is what is of interest in this study. Results show that reflected sunlight may help the general illumination in almost same level of significance as daylight from diffuse sky. It is also summarized that the contribution of reflected sunlight to general illumination through the year round may be even and uniform regardless of the season. Consequently, introduction of reflected sunlight should be regarded as one of the successful means to enhance the visual environment in quantitative and qualitative way.

• Journal of the Korean Solar Energy Society
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• v.31 no.6
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• pp.132-138
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• 2011

Inducing the natural lighting into building has been commonly applied to the spaces where artistic objects are displayed to create better visual environment for the appreciation. The direct natural lighting, especially through top lighting system may, however, bring forth discoloing of highly light-sensitive materials such as paintings or demanding additional cooling load. In addition, it causes to create glare against appreciators or to yield in visual distraction due to the extreme contrast on the inner surfaces of the spaces. Shading device such as louver is capable of preventing such voidable cases with careful manipulation. This study aims to provide basic design guide-line when the flat-form louver has to be applied to top lighting system. Interaction between the daylight and louver was simulated by Reluxpro program with variation of the attachment location, the angle of the lover, surface reflectivity, to obtain the illumination of the floor surface. This study yields the louver just under the top lighting window with 90 degree angle gives the most desirable way of employment when the uniform illumination on the floor surface is required.

• Journal of the Korean Solar Energy Society
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• v.33 no.5
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• pp.76-81
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• 2013

In our former study, we proposed that the AC-Model might be applied to various conditions. And we also introduced the method for daylighting that it was possible to reduce discomfort glare and to improve visual impressions as the supplementary type and blind-control type on the compound lighting. The purpose of this study was to examine the relationship between physical elements and psychological evaluation of lighting space. The study was made using an full-size space, which were equipped with various luminaries. We investigated the relationship between subjective evaluation and characteristics of light distribution and showed the high correlation between the evaluation rating and luminance distribution over whole room.

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2200-2206
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• 2012

One-dimensional $TiO_2$ array grown on optically transparent electrode holds a promise as a photoelectrode for photoelectrochemical water splitting; however, its crystal structure is rutile, imposing constraints on the potent use of this nanostructure. To address this issue, a heterojunction with type-II band alignment was fabricated using atomic layer deposition (ALD) technique. One-dimensional core/shell structured $TiO_2$/ZnO heterojunction was superior to $TiO_2$ in the photoelectrochemical water splitting because of better charge separation and more favorable Fermi level. The heterojunction also possesses better light scattering property, which turned out to be beneficial even for improving the photoelectrochemical performance of semiconductor-sensitized solar cell.

• Journal of the Korean Solar Energy Society
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• v.37 no.5
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• pp.1-11
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• 2017

A study on Nacelle Lidar (Light detection and ranging) measurement error and the data reliability verification was carried out at Haengwon wind farm on Jeju Island. For measurement data error processing, the characteristics of Nacelle Lidar measurements were analyzed by dividing into three parts, which are weather conditions (temperature, humidity, atmosphere, amount of precipitation), mechanical movement (rotation of wind turbine blades, tilt variation of Nacelle Lidar) and Nacelle Lidar data availability. After processing the measurement error, the reliability of Nacelle Lidar data was assessed by comparing with wind data by an anemometer on a met mast, which is located at a distance of 200m from the wind turbine with Nacelle Lidar. As a result, various weather conditions and mechanical movement did not disturb reliable data measurement. Nacelle Lidar data with availability of 95% or more could be used for checking Nacelle Lidar wind data reliability. The reliability of Nacelle Lidar data was very high with regression coefficient of 98% and coefficient of determination of 97%.

• KIEAE Journal
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• v.13 no.3
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• pp.97-104
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• 2013

This proposed simulation-based design study is based on the design of residential high-rise buildings in South-Korea. the purpose of this study is to evaluate the amount of daylighting performance passing through building glazing according to sky conditions, orientation of windows and each space of Apartment buildings. The clear sky includes sunshine and is intense and brighter at the horizon than at the zenith, except in the area around the sun. Daylight received within a building is directly dependent upon the sun's position and the atmospheric conditions. Orientation of the building generally used to refer to solar orientation which is the siting of building with respect to solar access. Although any building will have different orientations for its different sides, the orientation can refer to a particular room, or to the most important facade of the building. north-facing windows receive twice the winter sun than east and west facing windows, allowing light and warmth into the home. They can be easily shaded from the high summer sun to help keep the house cool. Ideally, the glazing area should be between 10-25% of the floor area of the room. This paper was calculated by a Desktop Radiance program. The space dimensions were based on a unit module of real constructed apartment having divided into five sections such as living room, room1, room2, room3 and kitchen.

• Journal of Sensor Science and Technology
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• v.22 no.6
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• pp.433-438
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• 2013

In this paper, we found surface shapes are affected by several parameters of RIE, such as RF power, pressure, temp, and process times. The reflectance of pyramid and half sphere structures show differences among shapes, size, height, and depth of those structures. We made about $1{\mu}m$ pyramid and half sphere shapes of silicon surface with RIE. For comparing the reflectance, pyramid and half sphere structures are fabricated with same height. Pyramid structure cell shows higher cell efficiency of 12.5% by 1.1% than one of half sphere structure of 11.4%. The light absorption is more increased through the pyramid structure than half sphere structure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.146-149
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• 2004

Porous silicon(PS) as an excellent light diffuser can be used as an antireflection layer without other antireflection coating(ARC) materials. PS layers were obtained by electrochemical etching(ECE) anodization of silicon wafers in hydrofluoric acid/ethanol/de-ionized(DI) water solution($HF/EtOH/H_2O$). This technique is based on the selective removal of Si atoms from the sample surface forming a layer of PS with adjustable optical, electrical, and mechanical properties. A PS layer with optimal ARC characteristics was obtained in charge density (Q) of 5.2 $C/cm^2$. The weighted reflectance is reduced from 33 % to 4 % in the wavelength between 400 and 1000 nm. The weighted reflectance with optimized PS layers is much less than that obtained with a commercial SiNx ARC on a potassium hydroxide(KOH) pre-textured multi-crystalline silicon(mc-Si) surface.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.319-319
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• 2010

Dye-sensitized solar cells (DSSCs) based on plastic substrates have attracted much attention mainly due to extensive applications such as ubiquitous powers, as well as the practical reasons such as light weight, flexibility and roll-to-roll process. However, conventional high temperature fabrication technology for glass based DSSCs, cannot be applied to flexible devices because polymer substrates cannot withstand the heat more than $150^{\circ}C$. Therefore, low temperature fabrication process, without using a polymer binder or thermal sintering, was required to fabricate necked $TiO_2$. In this presentation, we proposed polymer-inorganic composite photoelectrode, which can be fabricated at low temperature. The concept of composite electrode takes an advantage of utilizing elastic properties of polymers, such as good impact strength. As an elastic material, poly(methyl methacrylate) (PMMA) is selected because of its optical transparency and good adhesive properties. In this work, a polymer-inorganic composite electrode was constructed on FTO/glass substrate under low temperature sintering condition, from the mixture of PMMA and $TiO_2$ colloidal solution. The effect of PMMA composition on the photovoltaic property was investigated. Then, the enhanced mechanical stability of this composite electrode on ITO/PEN substrate was also demonstrated from bending test.

• Bulletin of the Korean Chemical Society
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• v.7 no.2
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• pp.120-124
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• 1986

In order to investigate effective solar energy conversion system, the light-induced electron transfer reactions have been examined across single-lamellar liposomes incorporated organic photosensitizers such as anthracene and naphthalene derivatives. We have observed photosensitized reduction of methyl viologen (1,1'-dimethyl-4,4'-$bipyridinium^{2+}$) dissolved in the exterior aqueous phase of the pigmented phospholipid liposomes when EDTA, as electron donor, is dissolved in the enclosed aqueous phase of the liposomes. The anthroyl stearic acid incorporated in the hydrophobic bilayer of liposomes leads to much less quantum yield for the photosensitized reduction of $MV^{2+}$ than the anthracene carboxylate incorporated in the outer hydrophilic layer. However, ${\beta}$-carotene with anthroyl stearic acid incorporated into the bilayer enhances the quantum yield significantly (${\Phi}{\simeq}0.2-0.3$), preventing the reverse reaction of electron transfer ($MV^+_\ {\rightarrow}MV^{2+}$) so that it might be useful for solar energy conversion into chemical energy. A naphthalene derivative, octadecyl naphthylamine sulfonic acid incorporated into the outer layer of liposomes results in less efficiency of $MV^{2+}$ reduction than anthroyl stearic acid. These results have been also tested with respect to lipid components of liposomes.