• Journal of the Korean Solar Energy Society
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• v.21 no.1
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• pp.43-49
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• 2001

Informations of the solar radiation component are essential for modeling various solar energy systems. These Informations are particularly used for middle and high temperature applications, those need concentrating direct normal insolation. In order to estimate the performance of concentrating systems, it is necessary to know the intensity of the beam radiation, as only this component can be concentrated. The Korea Institute of Energy Research(KIER) has began collecting solar radiation component data since August, 1996. KIER's component data will be extensively used by concentrating system users or designers as well as by research institutes.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.124-129
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• 2011

Since the horizontal global radiation and cloud cover are a main factor for designing any solar energy system, it is necessary to evaluate its characteristics all over the country. The work presented here are the investigation of horizontal global radiation and cloud cover in Korea. The data utilized in the investigation consist of horizontal global radiation and cloud cover collected for 27 years(1982.12~2008.12) at measuring stations across the country. The analysis shows that the annual-average daily horizontal global radiation is $3.61kWh/m^2$ and the annual-average daily cloud cover is 5.1 in Korea. We also constructed the contour map of cloud cover in Korea by interpolating actually measured data across the country.

• Journal of the Korean Solar Energy Society
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• v.32 no.3
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• pp.68-76
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• 2012

Since the solar energy resource is the main input for sizing any solar energy utilization system, it is essential to utilize the solar radiation data as an application and development of solar energy system increase. It will be necessary to understand and evaluate the insolation data. The Korea Institute of Energy Research(KIER) has begun collecting horizontal global insolation data since May, 1982 at 16 different locations in Korea and for the more detailed analysis, images taken by geostationary satellite may be used to estimate solar irradiance fluxes at earth's surface. It is based on the empirical correlation between a satellite derived cloud index and the irradiance at the ground. From the results, the measured data has been collected at 16 different stations and estimated using satellite at 44 different stations over the Korean peninsula from 1982 to 2010. The Result of analysis shows that the annual-average daily global radiation on the horizontal surface is 3.66 $kWh/m^2/day$ and estimated solar radiation fluxes show reliable results for estimating the global radiation with average deviation of -7.2 to +3.7 % from the measured values.

• Journal of Conservation Science
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• v.37 no.2
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• pp.90-100
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• 2021

Outdoor cultural buildings and their accessories receive different amounts of solar radiation depending on their location's latitude, azimuth, and tilt. Shading is also affected by the surrounding terrain and objects, necessitating individual and quantitative shading analysis. In July 2019, this study conducted a shading analysis on the tops, midpoints, and bottoms of wooden pillars in the azimuth of Cheongpunggak, a traditional building in South Korea's National Research Institute of Cultural Heritage. The shading analysis found that the solar access/shade predicted by the solar trajectory meter was 30 minutes slower than measured in the field. The highest solar access and solar radiation levels came from the south, followed by the west, east, and north. The pillars' bases received the highest solar access and solar radiation, followed by their midpoints and tops. Solar access was high at tilt 90°, but solar radiation was high at tilt 0°, due to the light-collection efficiency and the irradiance. Shading on the pillars' tops was caused by the roof eaves, while shading on the midpoints and bases were affected by the surrounding pillars, topography, and other objects. Simultaneous solar access at the tops, midpoints, and bottoms was possible for 365 days for the northwest, west, and southwest pillars but only from October to March for the south and southeast pillars.

• Current Optics and Photonics
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• v.1 no.4
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• pp.263-270
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• 2017

Solar radiation data measured by pyranometers is of fundamental use in various fields. In the field of atmospheric optics, the measurement of solar energy must be precise, and the equipment needs to be maintained frequently. However, there seem to be many errors with the existing type of pyranometer, which is an element of the solar-energy observation apparatus. In particular, the error caused by the thermal dome effect occurs because of the thermal offset generated from a temperature difference between outer dome and inner casing. To resolve the thermal dome effect, intensive observation was conducted using the method and instrument designed by Ji and Tsay. The characteristics of the observed global solar radiation were analyzed by classifying the observation period into clear, cloudy, and rainy cases. For the clear-weather case, the temperature difference between the pyranometer's case and dome was highest, and the thermal dome effect was $0.88MJ\;m^{-2}\;day^{-1}$. Meanwhile, the thermal dome effect in the cloudy case was $0.69MJ\;m^{-2}\;day^{-1}$, because the reduced global solar radiation thus reduced the temperature difference between case and dome. In addition, the rainy case had the smallest temperature difference of $0.21MJ\;m^{-2}\;day^{-1}$. The quantification of this thermal dome effect with respect to the daily accumulated global solar radiation gives calculated errors in the cloudy, rainy, and clear cases of 6.53%, 6.38%, and 5.41% respectively.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2094-2099
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• 2008

A numerical and experimental studies are carried out to investigate the transient heat transfer characteristics of 5kWth dish-type solar air receiver. Measured solar radiation and temperatures at several different locations are used as boundary conditions for numerical simulation. Many parameters' effects (reflectivity of the reflector, the thermal conductivity of the receiver body, transmissivity of the quartz window, etc.) on the thermal performance are investigated. Discrete Transfer Method is used to calculate the radiation heat exchange in the receiver. A transient heat transfer model is developed and the rate of radiation, convection and conduction heat transfer are calculated. Comparing the experimental and numerical results, good agreement is obtained. Using the numerical model, the transient heat transfer characteristics of volumetric air receiver for dish-type solar thermal systems are known and the transient thermal performance of the receiver can be estimated.

• New & Renewable Energy
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• v.16 no.1
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• pp.41-46
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• 2020

The share of agrophotovoltaics in the "renewable energy 3020", which is the Korean government policy for revitalizing new and renewable energy, is increasing gradually. In this study, the distribution of solar radiation received by crops growing on virtual farmland under a range of conditions, such as module height, module angle, shading ratio, and module type, was quantified and analyzed using an Ecotect program, which allows insolation analysis during the period from spring to fall. As the module angle increases, transmissive modules increase the amount of solar radiation delivered to the lower farmland. In addition, the difference between 3x12 Cell Type and 4x9 Cells Type, which are types of photovoltaic modules used in practice, was found to be small. The analysis results can be used as a design standard for the future establishment of agrophotovoltaic systems.

• Solar Energy
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• v.20 no.1
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• pp.31-43
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• 2000

The Korea Institute of Energy Research(KIER) has been collecting horizontal global radiation data since May, 1982 for 16 different locations. KIER's new data is expected to be extensively used by designer and researchers of solar systems in lieu of unreliable old ones. Unfortunately, the quality of the data has not always been properly mentioned. Some of them were taken at temporary field stations where the primary goal of the measurement was quick estimation of local solar radiation. The purpose of this study is to systematically identify errors in such data set using clear-day analysis in an effort to rehabilitate error-ridden old data. Clear-day analysis successfully uncovered solar radiation data that had questionable quality. Even through the rehabilitation process not necessarily improves the quality of data for daily or monthly mean, it can be used to improve the quality of data for monthly means of several years and the processed data can be used in various applications of solar energy with more confidence. A average ETR value of 0.63 obtained in this study is in good agreement with previous results obtained by other researchers.

• Smart Structures and Systems
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• v.25 no.1
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• pp.23-35
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• 2020

It is important to take into account the thermal behavior in assessing the structural condition of bridges. An effective method of studying the temperature effect of long-span bridges is numerical simulation based on the solar radiation models. This study aims to develop a time-varying solar radiation model which can consider the real-time weather changes, such as a cloud cover. A statistical analysis of the long-term monitoring data is first performed, especially on the temperature data between the south and north anchors of the bridge, to confirm that temperature difference can be used to describe real-time weather changes. Second, a defect in the traditional solar radiation model is detected in the temperature field simulation, whereby the value of the turbidity coefficient t_u is subjective and cannot be used to describe the weather changes in real-time. Therefore, a new solar radiation model with modified turbidity coefficient γ is first established on the temperature difference between the south and north anchors. Third, the temperature data of several days are selected for model validation, with the results showing that the simulated temperature distribution is in good agreement with the measured temperature, while the calculated results by the traditional model had minor errors because the turbidity coefficient t_u is uncertainty. In addition, the vertical and transverse temperature gradient of a typical cross-section and the temperature distribution of the tower are also studied.

• Journal of the Korean Solar Energy Society
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• v.36 no.4
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• pp.49-56
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• 2016

The objective of this work is to analyze the variation in energy performance for each flat plate collector connected in series. In this study, it was assumed that solar water heating system with annual solar fraction of 60% was installed in an office building in Seoul, South Korea. The transient energy performance corresponding to four cases, which are selected using different solar radiation and outdoor air temperature, is studied by analyzing the variation in outlet temperature, solar useful heat gain, and thermal efficiency of each collector. It is observed that the useful heat gain and the collector efficiency decrease continuously, and outlet temperature increases when increasing the number of collector connected in series. The long-term performance is assessed by evaluating the thermal efficiency of each collector for two solar radiation conditions ranging from 780 to $820W/m^2$ and from 380 to $420W/m^2$. It is found that the differences between the intercept and slope of the efficiency curves for first and eighth collectors are 3.68% and 6.74% for solar radiation of $800{\pm}20W/m^2$ and 8.57% and 12.90% for solar radiation of $400{\pm}20W/m^2$, respectively. In addition, it is interesting to note that annual useful heat gain and collector efficiency are reduced with similar rate of about 6.13% when increasing the collector area by connecting the collectors in series.