• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.595-598
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• 2005

The thermal performance of glass evacuated tube solar collectors are numerically and experimentally investigated. Four different shapes of solar collectors are considered and the performances of these solar collectors are compared. Dealing with a single collector tube, the effects of not only the shapes of the absorber tube but also the incidence angle of solar irradiation (beam radiation) on thermal performance of the collector are studied. However the solar irradiation consists of the beam radiation as well as the diffuse radiation. Also, the interference of solar irradiation and heat transfer interaction between the tubes exist in an actual solar collector. These effects are considered in this study experimentally and numerically the accuracy of the numerical model is verified by the experimental results. The result shows that the thermal performance of the absorber used a plate fin and U-tube is the best.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1294-1299
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• 2004

Transient radiative heat transfer is analyzed in a one-dimensional slab using finite volume method (FVM). In this study, the step, $2^{nd}$ order upwind, and QUICK schemes are used for incident diffuse radiation and collimated beam, respectively. The results for diffuse radiation show that all schemes applied in this study give good agreements with available published results. In case of collimated beam, however, the results show deviations from the analytical solutions. To successfully describe the propagations of collimated beam, shock capturing schemes such as TVD scheme are need to be developed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.3 s.246
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• pp.201-207
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• 2006

Transient radiative heat transfer is analyzed in a one-dimensional slab using finite volume method (FVM). In this study, the step, $2^{nd}$ order upwind, and QUICK schemes are used for incident diffuse radiation and collimated beam, respectively. The results fer diffuse radiation show that all schemes applied in this study give good agreements with available published results. In case of collimated beam however, the results show deviations from the analytical solutions. To successfully describe the propagations of collimated beam shock capturing schemes such as TVD scheme are need to be developed.

• Journal of the Korean Solar Energy Society
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• v.29 no.3
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• pp.12-18
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• 2009

The Knowledge of the solar radiation components are essential for modeling many solar energy systems. This is particularly the case for applications that concentrate the incident energy to attain high thermodynamic efficiency achievable only at the higher temperatures. In order to estimate the performance of concentrating thermal 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 January, 2002. KIER's component data will be extensively used by concentrating system users or designers as well as by research institutes. The theoretical analysis of solar radiation as a component has compared with the experimental data obtained by the KIER station. The Result of simulation analysis shows that the annual-average daily diffuse radiation on the horizontal surface is $1,457cal/m^2$ and daily direct radiation on the horizontal surface is $1,632cal/m^2$ for all over the 16 areas in Korea.

• Radiation Oncology Journal
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• v.25 no.4
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• pp.278-282
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• 2007

Purpose: Diffuse pigmented villonodular synovitis (PVNS) is an uncommon aggressive synovial proliferative disorder of unknown etiology affecting the joint linings. Though a histologically benign inflammatory process, because of its aggressive growth with bone destruction or recurrence, it is frequently suggested to occur as a low malignant neoplasm. Optimal treatment is surgery, but the local recurrence rate after radical synovectomy for diffuse PVNS is relatively high due to the infiltrative growth pattern. External beam radiotherapy with moderate doses or intra-articular instillation of radioactive isotopes may improve the likelihood of local control and long-term function in patients with incompletely resected or recurrent diffuse PVNS. I report one case of diffuse PVNS of the right knee joint treated with arthroscopic synovectomy and external beam radiotherapy is presented.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.8-12
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• 2009

The Knowledge of the solar radiation components are essential for modeling many solar energy systems. This is particularly the case for applications that concentrate the incident energy to attain high thermodynamic efficiency achievable only at the higher temperatures. In order to estimate the performance of concentrating thermal 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, 2002. KIER's component data will be extensively used by concentrating system users or designers as well as by research institutes. The Result of analysis shows that the annual-average daily diffuse radiation on the horizontal surface is $1,458cal/m^2$ and daily direct radiation on the horizontal surface is $1,632cal/m^2$ for all over the 16 areas in Korea.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.7
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• pp.659-668
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• 2005

The thermal performances of glass evacuated tube solar collectors are numerically investigated. Four different shapes of solar collectors are considered and the performances of these solar collectors are numerically investigated. Dealing with only collecting tube, the effects of not only the shape of the absorber tube but also the incidence angle of solar irradiation on the thermal performance of the collector are studied because the energy obtained by the absorber can be varied according to the incidence angle of solar radiation. However, the solar irradiation consists of the beam radiation as well as the diffuse radiation. Also, in actual system, the interference of solar irradiation and heat transfer interaction between the tubes should be considered. Therefore, this study considered these effects is carried out experimentally and numerically. The accuracy of the numerical model is verified by experiments. The result shows that the thermal performance of the absorber used a plate fin and U-tube is about $25\%$ better than those of the other models.

• Journal of Biosystems Engineering
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• v.13 no.2
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• pp.46-50
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• 1988

The estimation of beam radiation intensity on a tilted surface is very important to the design of a solar energy system. In order to get the beam radiation intensity, it is required to calculate the ratio of the diffuse solar radiation to the global radiation ($k_d$). The data measured at Chung-Buk National University. Cheong-ju, (from May 16, 1985 to Nov, 10, 1987) were analysed to define the relationship between hourly clearness index ($k_t$) and diffuse ratio ($t_d$). The results are is follow: 1. The percent of clearness index($k_t$) of less than 0.3 and of more than 0.8 were 2.7% and 3.1% respectively, and between 0.5 and 0.8 was 76.5%. 2. The regression equation between $k_t$ and $k_d$ was an exponential function as: $$k_d=\[{1\hspace{120}:\hspace{10}(k_t<0.1)\\1.28{\times}0.074^{k_t}\hspace{30}:\hspace{10}(0.1{\leq}=k_t<0.9)\\0.12\hspace{98}:\hspace{10}(0.9{\leq}=k_t)$$ There was a little difference between the result. of this study based on the data of 30 months and the results of previous study (ITRA 2(1):42-47, 1986.) based on the data of 8 months. 3. The hourly exponential regression equation between $k_t$ and $k_d$ was $k_d=A{\times}8^{k_t}$ and the values of constant A and coefficient B of the: equations are as the following table; 4. The percent of $k_d$ of less than 0.4 was 72.9% and of more than 0.7 was 6.6%. 5. Total mean value of $k_t$ and $k_d$ wert 0.56 and 0.32, respectively. From 10:00 to 15:00 o'clock the total mean value of $k_t$ was smaller that the hourly man value of $k_t$ and the one or $k_d$ larger.

• 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.24 no.3
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• pp.19-25
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• 2004

The measured solar radiation incident on tilted surfaces by all directions has been widely used as important solar radiation data in installing photovoltaic modules. To maximize the incident beam radiation, the slope, which is the angle between the plane of the surface in question and the horizontal, an4 the solar azimuth angles are needed for these solar photovoltaic systems. This is because the performance of the solar photovoltaic systems is much affected by angle and direction of incident rays. Recognizing those factors mentioned above are of importance, actual experiment has been performed in this research to obtain the an91e of inclination with which the maximum incident rays can be absorbed. The results obtained in this research could be used in installing optimal photovoltaic modules.