• Solar Energy
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• v.9 no.3
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• pp.13-24
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• 1989

Direct and diffuse components of solar radiation were measured inside and outside a single-span plastic greenhouse. To analyze the direct solar radiation inside the plastic greenhouse, the cross-section of the greenhouse was assumed to be circular. Then the direct solar radiation transmitted into the greenhouse was calculated theoretically, and compared with the experimental measurements. The results are summarized as follows: (1) The transmissivities of total solar radiation were about 65% on cloudy days and 50% on clear days. For cloudy days, the transmissivity of the total solar radiation was regarded as the transmissivity of sky diffuse radiation. (2) The ratio of the inside effective scattered component of direct solar radiation to the diffuse radiation was 60-65%. (3) It appeared that the seasonal variation of the transmissivity of total solar radiation was adversely affected by the transmissivity of direct solar radiation and the effective scattered coefficient. But the effect of the transmissivity of direct solar radiation was dominant factor. (4) Computer simulation showed that the inside direct solar radiation was decreased as the floor of the plastic greenhouse was higher. (5) The predicted value of the inside direct solar radiation was 3.3% to 29.0% higher than the measured value.

• Journal of Biosystems Engineering
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• v.23 no.5
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• pp.439-444
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• 1998

Effects of the number of spans, orientation and latitude on the transmissivities of direct and diffuse solar radiation in multispan glasshouse were analyzed using a computer simulation model (Kim and Lee, 1997). The number of spans did not affect the transmissivity of diffuse solar radiation, ranging 60∼61%. The transmissivities of direct solar radiation were 55∼64% for E-W orientation and 47∼70% for N-S orientation in ten multispan glasshouse. There was no effect of the latitude on the transmissivity of direct solar radiation in domestic regions. Differences in the transmissivity of direct solar radiation between single-span and multispan glasshouse were significant for E-W orientation during winter season; however, those were relatively small for N-S orientation throughout the year. Transmissivity of direct solar radiation decreased with the increasing number of spans for E-W glasshouse, whereas those for N-S glasshouse was hardly affected by the number of spans.

• 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.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.2135-2140
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• 2004

This study represented experimental research on the flat plate solar collector. For the flat plate Solar system, it is sensitive of the Global radiation. In Actually, it suppose to be dependent on the direct radiation. Also, the existing method's factors are depend upon Global radiation in the flat plate collector system. therefore it needs which is depend upon direct radiation. In this experiment, the flat plate collector is used for obtaining the method's factors of the direct radiation. As a result, the correct $({\tau}{\alpha})_e$ is found out for practical value.

• Journal of Bio-Environment Control
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• v.6 no.3
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• pp.176-182
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• 1997

A simulation model for the analysis of the transmissivity of direct and diffuse solar radiation In glasshouse was developed. This model would be applicable to investigate the influences of time of year, orientation and slope of glasshouse, dimensions of the frames used, and latitude of the site on the transmissivity of direct and diffuse solar radiation in single-span or multispan glasshouse. The transmissivity of diffuse solar radiation was 60.4％ for the single-span glass-house. It was independent of both orientation and time of year, During the winter season, the transmissivity of direct solar radiation was 67~69％ for the E-W orientation single-span glasshouse, which was 14~16％ higher than that for the S-N orientation. Oppositely the transmissivity of direct solar radiation for the S-N orientation was higher than that for the E-W orientation. during the autumn season. There was no influence of the latitude In the country on the transmissivity of direct solar radiation.

• Journal of the Korea Safety Management & Science
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• v.6 no.3
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• pp.87-97
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• 2004

The National Health Insurance Act, the Industrial Health Act and the School Health Act require chest radiography at least once a year. In chest radiographic examination, most group examinations use indirect X-ray primarily aiming at diagnosing diseases and enhancing people's health. This study purposed to minimize radiation exposure dose by comparing it between direct and indirect chest X-ray studies. According to the result of comparing and analyzing radiation exposure dose, the average incident dose and penetrating dose were 0.929μGy and 0.179μGy respectively in direct chest X-ray and 6.807μGy and 1.337μGy in indirect chest X-ray In order to minimize radiation exposure dose at direct and indirect chest X-ray, indirect X-ray should be excluded from group examination if possible. Moreover, it is necessary to control the quality of equipment (Q/A & Q/C) systematically and to avoid using unqualified equipment in order to reduce radiation exposure dose.

• Journal of the Korean Solar Energy Society
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• v.34 no.1
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• pp.105-116
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• 2014

The objective of this study was to compare and analyze of radiation environment between downtown and suburban area by observation of short, diffuse and long-wave radiation during summer season. The followings are main results from this study. 1) The trends of long-wave radiation is increasing from May to August and the variation of daily range is decreased. It is confirmed that the temperature was closely relevant to long wave radiation. 2) During observation period, suburban area is higher than downtown the value of direct solar radiation. 3) There are much direct solar radiation in suburban area than downtown. But, it was measured much more horizontal solar radiation at the downtown area. From the this result, we can conclude that diffuse radiation play a important role at horizontal solar radiation.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2198-2204
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• 2003

In order to make a match of the insufficient direct solar radiation, in this study, the target output is lowered to 9 kW smaller than 25 kW in former studies. It is also necessary to match the collector/receiver with engine/generator systems to accomplish the power level of a system. The simulation analyses of a dish solar power system with stirling engine are totally carried out to predict the system performance with the designed values. In addition, an influence of direct solar radiation on system performance and operation control is discussed in simulation. It is found that the diameter of concentrator could be made small to 8 m regardless of slope errors with 2.5 and 5.0 mrad radiation, and the operation range of mean pressure control. is wide even if the direct solar radiation is a quit low.

• The Journal of Korean Society for Radiation Therapy
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• v.23 no.1
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• pp.59-66
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• 2011

Purpose: Investigation of the clinical use of tangential fields technique using TOMO direct in comparison to conventional LINAC based radiation therapy after breast partial mastectomy. Materials and Methods: Treatment plans were created for 3 left-sided breast cancer patients who had radiation therapy after breast partial mastectomy by using wedged tangential fields technique, field in field technique (FIF), TOMO Direct, TOMO Direct intensity modulated radiation therapy (IMRT) under the normalized prescription condition ($D_{90%}$: 50.4 Gy/28 fx within CTV). Dose volume histogram (DVH) and isodose curve were used to evaluate the dose to the clinical target volume (CTV), organ at risk (OAR). We compared and analyzed dosimetric parameters of CTV and OAR. Dosimetric parameters of CTV are $D_{99}$, $D_{95}$, Dose homogeneity index (DHI: $D_{10}/D_{90}$) and $V_{105}$, $V_{110}$. And dosimetric parameters of OAR are $V_{10}$, $V_{20}$, $V_{30}$, $V_{40}$ of the heart and $V_{10}$, $V_{20}$, $V_{30}$ of left lung. Results: Dosimetric results of CTV, the average value of $D_{99}$, $D_{95}$ were $47.7{\pm}1.1Gy$, $49.4{\pm}0.1Gy$ from wedged tangential fields technique (W) and FIF (F) were $47.1{\pm}0.6Gy$, $49.2{\pm}0.4Gy$. And it was $49.2{\pm}0.4$ vs. $48.6{\pm}0.8Gy$, $49.9{\pm}0.4$ vs. $49.5{\pm}0.3Gy$ Gy for the TOMO Direct (D) and TOMO Direct IMRT (I). The average value of dose homogeneity index was W: $1.1{\pm}0.02$, F: $1.07{\pm}0.02$, D: $1.03{\pm}0.001$, I: $1.05{\pm}0.02$. When we compared the average value of $V_{105}$, $V_{110}$ using each technique, it was the highest as $34.6{\pm}9.3%$, $7.5{\pm}7.9%$ for wedged tangential fields technique and the value dropped for FIF as $16.5{\pm}14.8%$, $2.1{\pm}3.5%$, TOMO direct IMRT as $7.5{\pm}8.3%$, $0.1{\pm}0.1%$ and the TOMO direct showed the lowest values for both as 0%. Dosimetric results of OAR was no significant difference among each technique. Conclusion: TOMO direct provides improved target dose homogeneity over wedged tangential field technique. It is no increase the amount of normal tissue volumes receiving low doses, as oppose to IMRT or Helical TOMO IMRT. Also, it simply performs treatment plan procedure than FIF. TOMO Direct is a clinical useful technique for breast cancer patients after partial mastectomy.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.4
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• pp.542-550
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• 1998

A direct contact heat exchanger using particle-suspended gas as a heat transfer medium is analyzed with an extended emphasis on the radiation, i. e., considering the radiation by both gas and particles. While the Runge-Kutta method is used for a numerical analysis of the momentum and energy equations, the finite volume method is utilized to solve the radiative transfer equation. Present study shows a notable effect by the gas radiation in addition to the particle radiation, especially when changing the chamber length as well as the gas and particle mass flow rate. When the gas and particle mass flow rate is raised, the gas temperature in the particle heater still increases as the gas absorption coefficient increases, which is different from the results for the small scale heat exchanger.