• KIEAE Journal
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• v.14 no.4
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• pp.35-45
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• 2014

The main objective of this study is to provide an effective algorithm of the transmitted solar radiation calculation through window glazing on a clear day. This algorithm would be used in developing a computer program for fenestration system analysis and shading device design. Various simulation methods have been evaluated to figure out the most accurate and effective procedure in estimation of transmitted solar radiation on a tilted surface on a clear day. Characteristics of simulated results of each step have been scrutinized by comparing them with measured results of the site as well as results from other simulation programs. Generally, the Duffie & Beckman's solar calculation method introducing the HDKR anisotropic model provided the most reliable simulation results. The DOE-2 program usually provided over-estimated simulation results. The estimation of extraterrestrial solar radiation and beam normal radiation were conducted pretty accurately. However, the solar radiation either on horizontal surface or on tilted surface involves complicated factors in estimation. Even though the estimation results were close to the real measured data during summer when solar intensity is getting higher, the estimation provided more error when solar intensities were getting weaker. The convex polygon clipping algorithm with homogeneous coordinates was fastest model in calculation of sunlight to shaded area ratio. It could not be applied because of its shape limitation.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.63-67
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• 2011

KnowledgThe Korea Institute of Energy Research(KIER) has begun collecting horizontal global insolation data since May, 1982 at different locations. Because of a poor reliability of existing data, KIER's new data will be extensively used by the solar system users as well as by research institutes. But the quality of solar insolation data is not always good. This reports on an attempt to identify systematic error in such data using clear-day analysis for data rehabilitation. Clear-day analysis is successful in uncovering solar insolation data of questionable quality. It is not proven that rehabilitation process can improve the quality of data for daily or monthly means, but it is suggested that the method can be used to improve the quality of data for monthly means of several years for use in many applications of solar energy plarming. Earlier studies finding a maximum ETR of about 0.80 are confirmed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.3
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• pp.256-267
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• 1987

Changes of light intensity under and above shading materials were measured at different relative light intensity(R.L.I. 5% of common straw shading, 15% of polyester shading and 20% of polyester shading at 12 o'clock on clear day) and lines(lst, 3rd and 5th lines) on clear and cloudy days in 5-year -old ginseng plant populations. Rates of photosynthesis and respiration, microclimate and root yield were also measured in field. Air temperature of R.L.I. 5% were lower 2$^{\circ}C$ compared with R.L.I. 15% and lower 3$^{\circ}C$ compared with R. L. I. 20% from 12 to 14 o'clock on clear day, but there were not difference among R. L. I. on cloudy day. Relative humidity of R. L. I. 5% were higher 5% compared compared with R.L.I. 20% from 10 to 14 o'clock on clear day, R. L. I. on cloudy day. Light intensity were below 5,000 lux at R.L.I. 5%, about 15,000 lux at R.L.I. 15% and about 20,000 lux at R.L.I. 20% from 10 to 15 o'clock on clear day. But light intensity were below 3, 000 lux at R. L. I. 5% about 10, 000 lux at R. L. I. 15% and about 15, 000 lux at R. L. I. 20% from 10 to 15 o'clock on cloudy. Photosynthetic rate of R.L.I. 15% and R.L.I. 20% were higher compared with R.L.I. 5% on clear and cloudy days. Tatal photosynthesis in a day were increased by R.L.I. 5%, 20%, 15% in turn on clear and cloudy days. R. L. I. 15% and 20% were not notable difference of photosynthetic rates among lines but R. L. I. with R. L. I. 15%, and higher 8% but there were not different among 5% was notable difference of one. Root fresh weight were increased by R.L.I. 5%, 20% and 15% in turn and R.L.I. 15% and 20% were not notable difference of root yield among lines but R. L. I. 5% was notable difference of one.

• Asian Journal of Atmospheric Environment
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• v.4 no.3
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• pp.141-149
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• 2010

Aerosol size and number concentration were observed in the atmospheric boundary layer over Beijing (from near the ground to 1,200 m) on March 15 (a clear day) and 16 (a dusty day), 2005. The results were further compared with lidar measurements in order to understand the dependency of extinction on the particle size distribution and their vertical changes. The boundary layer atmosphere was composed of several sub-layers, and a dry air layer appeared between 400 and 1,000 m under the influence of dust event. In this dry air layer, the concentration of the fine-mode particles (diameter smaller than $1.0\;{\mu}m$) was slightly lower than the value on the clear day, while the concentration of coarse-mode particles (diameter larger than $1.0\;{\mu}m$) was remarkably higher than that on the clear day. This situation was attributed to the inflow of an air mass containing large amounts of Asian dust particles and a smaller amount of fine-mode particles. The results strongly suggest that the fine-mode particles affect light extinction even in the dusty atmosphere. However, quantitatively the relation between extinction and particle concentration is not satisfied under the dusty atmospheric conditions since laser beam attenuates in the atmosphere with high concentration of particles. Laser beam attenuation effect becomes larger in the relation between extinction and coarse particle content comparing the relation between extinction and fine particle content. To clarify this problem technically, future in situ measurements such as balloon-borne lidar are suggested. Here extinction was measured at 532 nm wavelength. Measurements of extinction at other wavelengths are desired in the future.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.274-277
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• 2011

We measured a solar irradiation of vertical and horizontal surface per azimuth in southern area of Korea using pyrheliometer. In comparison with the provided data from ASHRAE and CIBSE, the average amount of solar irradiation has much variation of 10 to 150% in reference with north direction. In the clear day, the measured value has much difference with the value of ASHRAE and there is similar trend in case of CIBSE. The reason why amount of irradiation of clear day is differ from the average value, is able to be assumed that the value of ASHRAE and CIRSE is made of assumption based on clear days. The result of analysis of ASHRAE and CIBSE values according to the amount irradiation value for vertical and horizontal surface per azimuth using the MBE, RSME, and t-Statistic show that the CIBSE value has more reliability for the MBE, RMSE, and t-Statistic values than ASHRAE value.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.8
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• pp.553-561
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• 2010

This study examines the influence of light variation on visual responses in a small office space where a daylight dimming control system is applied. Field measurements and survey were performed in a full-scale mocked-up small office space under clear sky day conditions. Maximum fluctuation range for desktop was 133.5 lx and it just happened once for entire monitoring period. For the majority of time, the fluctuation range did not exceed 50 lx, which did not cause visual discomfort to subjects. The daylight dimming control system successfully kept required illuminance levels for an office environment when desktop illuminance by daylight ranged up to 300 lx. The most serious contributor to the sensation of glare was direct daylight through window. The dimming of electric light was not a significant contributor to visual discomfort for the subjects under clear sky day conditions. Visual comfort was significantly influenced by the sensation of glare, feeling for visual stimulation and distraction, and required illuminance level.

• Solar Energy
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• v.11 no.1
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• pp.3-15
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• 1991

In this study global radiation and global illumination are directly measured and diffuse radiation and diffuse illumination measured utilizing semi-circular shadow ring. By analyzing measured radiation data, clear and overcast sky are classified according to the sky classification method used in Mantes, France. Measured illumination data are analyzed and 1) Clear sky illumination on a horizontal surface as a function of solar altitude. 2) Overcast sky illumination on a horizontal surface as a function of solar altitude, 3) Monthly variation of illumination. 4) Cumulative percentage of illumination, 5) Daylight intensity as a function of hours in a typical day, 6) Average number hours per day of illumination above 10 and 20klx are presented as a climatic data for daylighting design for Seoul, Korea.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.10
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• pp.38-46
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• 2011

Recently, interests in renewable energy have gradually increased. Of various renewable energy, Photovoltaic system has the properties affected by weather. This paper discusses the economic evaluation based on insolation data analysis. Real insolation data were obtained by radiation measurement device installed in projected photovoltaic system site during 20 months. Obtained real insolation data were standardized using clear day analysis. Standardized data are greater than obtained real insolation data and were used as parameters of RETScreen for the economic evaluation. In results, capacity(30[kW]) of soon cheon is shown the most B/C(1.20). Applied methods have effectively done to develop photovoltaic system.

• Journal of the Korean Solar Energy Society
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• v.21 no.2
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• pp.19-25
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• 2001

Atmospheric clearness index is one of the main factors in the evaluation of the atmospheric condition. The work presented here is the evaluation and comparison of atmospheric conditions using clearness factor for 15 cities in Korea. Clearness factor was computed with the assumed clear day, where clear day model was obtained using average global insolation, cloud amount and duration of sunshine measured for 18 years (1982-1999). The dearness index proposed in this work could be used by the atmospheric circumstance analysts, solar designers and users.

• Solar Energy
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• v.8 no.1
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• pp.107-121
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• 1988

The Korea Institute of Energy and Resources (KIER) has begun collecting horizental insolation data since May, 1982 at different locations. Because of a poor reliability of existing data, KIER's new data will be extensively used by the solar system users as well as by research institutes. But, the quality of the solar radiation data is not always good. This reports on an attempt to identify systematic error in such data using clear-day analysis for data rehabilitation. Clear-day analysis is successful in uncovering solar radiation data of questionable quality. It is not proven that rehabilitation process can improve the quality of data for daily or monthly means but it is suggested that the method can be used to improve the quality of data for monthly means of several years for use in many applications of solar energy planning. Earlier studies finding a maximum ETR of about 0.80 are confirmed.