• Journal of the Korean Solar Energy Society
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• v.34 no.1
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• pp.19-27
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• 2014

Exterior vertical illuminance is an important factor for lighting control. But, there are not many researches about the exterior illuminance on a vertical surface. In this study, we predicted the exterior illuminance on a vertical surface using vertical luminous efficacy. First, we calculated the vertical luminous efficacy according to the sky clearness category. And we performed the statistical analysis of the measured and the calculated illuminance with luminous efficacy. The MBE and RMSE of the predicted exterior illuminance were-1.2% and 15.5%, respectively. Second, the annual illuminance on a vertical surface calculated with the luminous efficacy and the short-term measured solar irradiance was suggested in this study.

• Journal of the Korean Solar Energy Society
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• v.28 no.6
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• pp.78-86
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• 2008

The aim of this paper is to show the daylight environment of a light pipe system according to sun movement. A light pipe system has been mounted on the roof of the windowless full scale model: the solar spot has diameter of 0.65m and is 1.3m long, giving an aspect ratio of 1:2. The full scale model was installed on the rooftop of the SHINAN apartment in Yongin city that has no obstructions against sunlight. The test room is equipped with sensors for the measurements of the internal illuminance and has an area of 6m(W)$\times$6m(D)$\times$4m(H). The system has been monitored with a data-logger to evaluate the cumulative distribution of illuminance on a floor-plane from 16th, April to 29th, May, 2008 over one month and selected clear sky condition. For the daylight performance of floor area, the totally 49 measuring points has been used to determine the internal illuminance and an HP datalogger(HP34970A) records the measurements for one consecutive month. The horizontal external illuminance has been measured with two outdoor sensors. This paper presents the results of monitoring light pipe system with internal/external illuminance ratio and cumulative frequency distribution of floor-plane illuminance are discussed The results show that lightpipe is proficient device for introducing daylight into the building. However It provided different daylight indoor environment with wide or narrow Interquatile range of illuminance, internal/external illuminance ratio and cumulative frequency distribution according to solar positions under suuny sky condition. For more achieving the improvement of lightpipes also include energy savings, user visual comfort with various indicators; seasonal solar height, room and lightpipes geometries.

• Journal of the Korean Solar Energy Society
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• v.31 no.6
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• pp.86-94
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• 2011

For accurate dayligh tsimulation, accurate exterior illuminance is necessary. But, Korea Meteorological Agency provides only the solar irradiance data. Thus, there is a need for the research on luminous efficacy. In this study, global horizontal irradiance, diffuse horizontal irradiance, global horizontal illuminance, and diffuse horizontal illuminance were measured to calculate the luminous efficacy in SEOUL. And, we evaluated the applicability of the Perez's model by comparing the measured data and calculated data. As a result, measured global luminous efficacy is 126(110~129)lm/W and diffuse luminous efficacy is 127(115~133)lm/W in Seoul. Perez's model was relatively accurate with 5% difference in the diffuse luminous efficacy. But, it can be predicted about 15% lower in the global luminous efficacy.

• Journal of the Korean Solar Energy Society
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• v.36 no.6
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• pp.37-46
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• 2016

In this study, long-term global illuminance data for 19 selected cities are calculated from modeled solar radiation data, AEER's TMY2. Perez model in Daysim daylight simulation tool is used for the solar radiation to illuminance conversion. And then, daylight availability in an unit office space is evaluated for the 19 cities. For this evaluation, various daylight performance indices are reviewed since static daylight performance index such as daylight factor (DF) and annual average global illuminance value is not suitable for actual performance evaluation in terms of visual comfort and light energy saving of a space. This study evaluated daylighting performance of prototypical office space module by introducing DA (daylight autonomy) and UDI (Useful Daylight Illuminance) index for major cities of Korea. Result shows that there is upto 18% of illuminance level difference with annual average global illuminance data, but if we consider useful daylight in a space the illuminance level difference among the cities are only within 5%. This means that for sustainable building design especially in daylight design, amount of annual global illuminance is not important factor even in cloudy cities. Daylight design and daylight harvesting system would return similar energy saving impact regardless of building location.

• Journal of the Korean Solar Energy Society
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• v.24 no.2
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• pp.17-23
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• 2004

Daylight illuminance levels in a small space were calculated using the Superlite program under limited conditions of the turbidity and thickness of condensible water of atmosphere. Three sky conditions(clear sky with direct sun, clear sky with no direct sun, overcast sky with no direct sun) were used. The atmospheric conditions significantly impacted the illuminance levels under especially a clear sky with direct sun. The overcast sky with no direct sun provided no difference for the illuminance levels in the space. As the calculation points moved away from a window, reflected illuminance levels gradually increased but direct illuminance levels significantly decreased.

• Journal of the Korean Solar Energy Society
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• v.40 no.1
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• pp.35-47
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• 2020

Due to the large window area, the lighting environment of the educational space between the window and deep part of the room is not uniformly illuminated, and the phenomenon of glare is severe. For this reason, the daylight performance of DSC-BIPV windows was analyzed in order to improve the natural lighting in the educational sector. The method derives the correlation with natural lighting by measurement and simulation. Dynamic simulation confirmed that the average illuminance of the target space was higher at later than the early afternoon. The performance of natural lighting at 40% and 30% transmission of DSC has the effect of significantly reducing the amount of excess light in existing windows. Nevertheless, the actual average illuminance in all seasons corresponds to the standard illuminance of the educational facility, 300 Lux. In addition, the uniformity is also seen through the skylight illuminance ratio.

• Solar Energy
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• v.19 no.1
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• pp.47-57
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• 1999

A building and the solar are related to the privilege of solar benefit. To make step, it is required to build up an object, chase the position of object and the solar, find the shadow occurrence. On the subject of direct illuminance, an intensive emission of irradiation is proposed to directly project to the benefit area. Simultaneously on the indirect illuminance, the integration of a finite element incident to the benefit area can be multiplied by the hemisphere luminance. A caution should be paid to eliminate the occupation area of the object around on the hemispherical sky, which can help run more accurate prediction.

• Journal of the Korean Solar Energy Society
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• v.26 no.3
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• pp.33-43
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• 2006

Daylight dimming control system was analyzed for an indirect lighting system in a small office space with a double skin envelope system. Computer simulations were performed for photosensors with three shielding conditions. The photosensors were placed on the center of ceiling, and backwall. Three sky conditions defined by CIE were considered. Overall, control performance was not very excellent for all conditions. Fully-shielded photosensor achieved good control performance for some cases, but partially-shielded and unshielded photosensors failed to achieve target illuminance. The variation in desktop illuminance due to daylight was examined for a variety of daylight conditions. Linear correlation between desktop illuminance and photosensor illuminance was analyzed using ANOVA.

• Journal of The Korean Astronomical Society
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• v.45 no.5
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• pp.111-116
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• 2012

We present a mathematical model that predicts the variation of illuminance during a solar eclipse, considering continuous effects of limb darkening. We assume that (1) the Sun and the Moon constitute perfect spheres, (2) the Moon crosses the Sun with a constant apparent velocity, and (3) sunspots, prominences, and coronae can be neglected. We compare predictions of this model with actual measurements made by M$\ddot{o}$llmann & Vollmer (2006) during a total solar eclipse in Turkey, and with predictions of existing models. The new model is shown to describe the actual phenomenon more accurately than existing models.

• KIEAE Journal
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• v.15 no.5
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• pp.107-112
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• 2015

Purpose: This study desires to investigate an effect of indoor temperature, humidity, and illuminance targeting a planting system of double-skin facade and cavity space adjacent to the outside within a certain period of winter. Through this, the study suggests a basic material about an energy conservation effect of double window system using planting to reduce heating load of a building in winter, so desires to contribute to indoor thermal comfort effect and illuminance correction study of double window and indoor plant. Method: Considering effects such as day and night climatic elements and air conditions in winter, illuminance measurement was conducted through a double-skin facade of space, a subject of the measurement, on the basis of practical residence time of a resident, and this study analyzed characteristics of indoor illuminance about this. The study measured and compared a change of insolation, dry-bulb temperature, and relative humidity at each indoor-outdoor measuring point, so measured and compared characteristics of an indoor temperature effect by elements of double-skin facade and indoor plant. Result: Through this study, the researcher could determine that indoor plant within double window in winter not only blocks solar radiation but also photosynthesizes, so is somewhat disadvantageous to winter thermal comfort reducing heating load. In addition, solar radiation going through interior plays a role to bring down somewhat high humidity to about 50% of reasonable humidity, so plays a direct role of maintenance of comfortable indoor space. Although there are effects such as blocking of solar radiation and temperature reduction, this has a positive influence on humidity control and proper illuminance distribution. The researcher could determine that illuminance, temperature, and humidity by solar radiation penetration for the whole measuring time play a role to supplement indoor environment mutually.