• Journal of the Korean Solar Energy Society
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• v.23 no.3
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• pp.23-28
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• 2003

The purpose of this study is to procure basic data to be used for solar power plant and concentrating collector designs. Site elevation is one of the major factors which influences the incoming insolation to the earth surface. Because the nonpermanent gases such as ozone, water vapor are unmixed components of the atmosphere and their concentrations are the function of height, the site elevation effects the relative proportion of the atmospheric constituents. We have measured solar radiation on Jiri Mt. (1,400m) and in Gurye area(115m) at the near same latitude. These values were then compared to obtain their characteristics and to investigate the potential for the solar utilization for both high and low elevated areas. From the experimental results, we concluded that 1) Daily mean horizontal global radiation and normal beam radiation on Mt. Jiri are 9.5%, and 35.3% higher than Gurye area respectively for a clear day. 2) A significant difference in atmospheric clearness index is observed between Mt. Jiri and Gurye areas.

• Journal of the Korean Solar Energy Society
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• v.35 no.3
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• pp.73-79
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• 2015

In this study, a thermal storage performance and characteristics of daily operation were investigated when the air and the liquid were heated simultaneously by a hybrid solar air-water heater that can make hot water as well as heated air. The hybrid solar air-water heater is kind of a flat plate solar collector that can make hot water and heated air by installing air channel beneath absorber plate of traditional flat plate solar collector for hot water. As a result of daily operation, maximum water temperature reached in a thermal storage was shown $44^{\circ}C$ on 73kg/h of air mass flow rate and about $40^{\circ}C$ on 176kg/h of air mass flow rate. Thus, the necessity of heating water in thermal storage by operating only liquid side was confirmed when the temperature of liquid in thermal storage is lower than we need. In case of efficiency investigated on daily operation, the thermal efficiency of the liquid side was decreased with increment of the inlet liquid temperature and decrement of the solar radiation, but efficiency of the air side was increased with increment of inlet liquid temperature difference as the traditional solar air heater. Total thermal efficiency of the collector was shown from 65.85% to 78.23% and it was decreased with increment of the inlet liquid temperature and decrement of solar radiation same as the traditional system.

• Korean Journal of Agricultural and Forest Meteorology
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• v.14 no.4
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• pp.260-264
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• 2012

Accuracy of daily solar radiation estimated from a Mountain Microclimate Simulation Model (MT-CLIM) was assessed for seven observation sites with complex topography in Uiseong County. The coefficient of determination ($R^2$) between the observed and the estimated daily solar radiation was 0.52 for 7 sites for the study period from 1 August to 30 September 2009. Overall, the MT-CLIM overestimated the solar radiation with root mean square error (RMSE) of $3.83MJ\;m^{-2}$ which is about 25% of the mean daily solar radiation ($15.27MJ\;m^{-2}$) for the study period. Considering that the pyranometer's tolerance is ${\pm}5%$ of standard sensor, the RMSE of MT-CLIM was too large to accept for a direct application for agricultural sector. The reliability of solar radiation estimated by MT-CLIM must be improved by considering additional ways such as using a topography correction coefficient.

• Journal of the Korean Solar Energy Society
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• v.26 no.3
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• pp.53-62
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• 2006

Since the direct normal radiation and clear day are a main factor for designing any solar thermal and photovoltaic concentrating system, it is necessary to evaluate its characteristics all over the country. The work presented here are the investigation of direct normal radiation and clear day in Korea. The data utilized in the investigation consist of direct normal radiation collected for 14 years('90. 12${\sim}$2004. 12) and clear-day collected for 23 years($1982{\sim}2004$) at measuring stations across the country. The analysis shows that the annual-average daily direct normal radiation is 5.4 kWh/m2 and the annual-average total clear-day is 92.7 days in Korea. We also constructed the contour map of direct normal radiation and clear-day in Korea by interpolating actually measured data across the country.

• Journal of the Korean Solar Energy Society
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• v.31 no.3
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• pp.48-56
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• 2011

Since the horizontal global radiation and hours of bright sunshine are a main factor for designing photovoltaic system, it is necessary to evaluate its characteristics all over the country. The work presented here are the investigation of horizontal global radiation and hours of bright sunshine in Korea. The data utilized in the investigation consist of horizontal global radiation and hours of bright sunshine collected for 28years(1982.12~2009.12) at measuring stations across the country. The analysis shows that the annual-average daily horizontal global radiation is3.61kWh/m2 and the annual-average daily hours of bright sunshineis 5.1 Hrs in Korea. We also constructed the contour map of hours of horizontal global radiation and hours of bright sunshine in Korea by interpolating actually measured data across the country.

• Journal of Environmental Science International
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• v.20 no.12
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• pp.1599-1605
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• 2011

To evaluate heat environment surrounding plants diurnal change of leaf temperature in the broad-leaved deciduous and evergreen trees was measured with microclimatic environmental factors including global solar radiation, and upward and downward long wave radiation. Maximum daily solar radiation was 961.2 and 976.3 w/$m^2$ in August 9 and 23, respectively. Upward long wave radiation was slightly higher than downward long wave radiation, showing 404.2 w/$m^2$ in August 9 and 394.5 w/$m^2$ in August 23. In addition, daily maximum vapor pressure deficit was 5.42 and 6.84 kPa in August 9 and 23, respectively, indicating high evaporative demand. Quercus glauca and Acer mono was differently responded to changing light regimes. On August 9, leaf temperature at the top-positioned leaves of Acer plants was higher than air temperature as well as those of Quercus plants in the morning. This indicates that stomata in Acer plants were closed by heat stress or water stress in the morning, while Quercus plant maintained active transpiration by opening stomata. These results indicated that improved light regimes such as gap opening in the closed forest may not always affect positively in the physiology of understory plants.

• Journal of the Korean Solar Energy Society
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• v.31 no.4
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• pp.72-79
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• 2011

Solar radiation data are the best source of information for estimating average incident radiation. Lacking this or data from nearby locations of similar climate, it is possible to use empirical relationships to estimate radiation from days of hours of bright sunshine. It is necessary to estimate the regression coefficients in order to predict the daily global radiation on a horizontal surface. Therefore many different equations have proposed to evaluate them for certain areas. In this work a new correlation has been made to predict the solar radiation for 16 different areas over Korea by estimating the regression coefficients taking into account hours of bright sunshine. Particularly, the proposed straight line regression model shows reliable results for estimating the global radiation on a horizontal surface with monthly average deviation of -0.2 to +0.5% and each station annual average deviation of -1.6 to +1.7% from measured values.

• Journal of the Korean Solar Energy Society
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• v.27 no.3
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• pp.95-105
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• 2007

Since the solar radiation is the main input for sizing any solar photovoltaic system, it will be necessary to understand and evaluate the solar radiation data. The works presented here is the analysis of solar radiation data for East-North Asia areas. The data utilized in the analysis consist of the global radiation on horizontal surface, measured at 2 different stations during 3 years for the period from 2002 to 2004 and estimated using satellite at 27 different stations over the China and Mongolia. Also the measured data has been collected at 16 different stations all of the South Korea and estimated using satellite at 12 different stations over the North Korea from 1982 to 2005. The Result of analysis shows that the annual-average daily global radiation on the horizontal surface is $3.57\;MJ/m^2$. We conclude, based on the analysis, that East-North Asia areas have sufficient solar energy resources for the photovoltaic power generation system.

• Journal of the Korean Solar Energy Society
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• v.30 no.2
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• pp.72-80
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• 2010

The main thrust of this paper is to investigate a practical way of generating the monthly averaged daily horizontal solar radiation in Korea. For estimating the horizontal solar radiation, the clearness index($K_T$) and the clearness number($C_N$) which are required for the use of Liu and Jordan's model and ASHRAE Clear Sky model were derived based on the measured weather data. Third-order polynomials returning $K_T$ and��$C_N$ for a given location were derived as a function of cloud amount, month, date, latitude and longitude. The predicted monthly averaged daily horizontal solar radiation values were compared with those acquired from the established design weather data. The MBE(Mean Bias Error) and RMSE (Root Mean Squares for Error) between the predicted values and the measured data were near zero. It means that the suggested third-order polynomials for $K_T$ and $C_N$ have good applicability to Liu and Jordan's model and ASHRAE Clear Sky model.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.5 no.3
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• pp.178-197
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• 1976

Based on the measurement data on Radiation on a Horizontal Surface at 84 different areas in South Korea which were collected and recorded by the Central Meteorological Office, the average values in the period of 5 years from 1971 thru 1975 at 12 particular areas of Gangreung, Gyeongju, Gwangju, Gimhae, Mogpo, Seoul, Iri, Jeju, Jinju, Cheongju and Chungju are indicated in this report. For above 12 areas the following data have been obtained and are indicated in each tables. Annual totalization of Radiation on a Horizontal Surface and its yearly averaged daily totalization$cdots$Table 1. Monthly totalization of Radiation on a Horizontal Surface and its monthly averaged daily totalization$cdots$Table 2 Maximum and minimum values of daily totalization of Radiation on a Horizontal Surface$cdots$Table 3 Daily variation of monthly averaged Radiation on a Horizontal Surface$cdots$Table 4 thru 15 Decade averaged Radiation on a Horizontal Surface$cdots$Table 16 thru 27