• Journal of Radiation Protection and Research
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• v.32 no.4
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• pp.178-183
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• 2007

Neutrons are high LET (linear energy transfer) radiation and cause more damage to the target cells than x-rays or gamma rays. The damage from neutrons is generally considered fatal to a cell and neutrons have a greater tendency to cause cell death through direct interaction on DNA. We performed experiments to measure growth delay ratio and oxygen enhancement ratio (OER) in mouse model system. We inoculated EMT-6 cells to the right hind leg of BALB-c mouse and X-rays and neutron beams were given when the average volume of tumors reached $200-300mm^3$. We irradiated 0, 11, 15.4 Gy of X-ray and 0, 5, 7 Gy of fast neutron beam at normoxic and hypoxic condition. The volume of tumors was measured 3 times per week. In x-ray experiment, growth delay ratio was 1.34 with 11 Gy and 1.33 with 15.4 Gy in normoxic condition compared to in hypoxic condition, respectively. In neutron experiment, growth delay ratio was 0.94 with 5 Gy and 0.98 with 7 Gy, respectively. The OER of neutron beam was 0.97. The neutron beam was more effective than X-ray in the control of hypoxic tumors.

• Journal of Bio-Environment Control
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• v.11 no.2
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• pp.56-60
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• 2002

Since the transmittance of solar radiation directly affected by the structural frames of greenhouse can be changed according to the ratio of diffuse to direct radiations, it is necessary to investigate the transmittance of greenhouse at the different weather conditions. We can easily get the data of total solar radiation from the Meteorological Administration, but we have to personally measure the photosynthetic photon flux (PPF). If the relationship between total solar radiation and PPF is established, the PPF can be simply acquired from the relationship. Sol it is required to develop the equation to calculate PPF depending on weather condition. This study was conducted to determine the transmittance of PPF at canopy level in glasshouse and the correlation between total solar radiation and PPF at clear and cloudy days. The variation phase of greenhouse transmittance at clear day was very different from that at cloudy day. It was concluded that the proper transmittance, depending on the weather condition, should be adopted to calculate the accurate total solar radiation and PPF in greenhouse. The transmittance of solar radiation was the same as that of PPF in greenhouse. It was confirmed that the ratio of PPF to total radiation increased as the amount of cloud increased. The correlation between the hourly total solar radiation and PPF was derived.

• Food Science and Preservation
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• v.13 no.5
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• pp.531-537
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• 2006

This study was conducted to evaluate the combined effect of heating and gamma irradiation on the shelf-stability and quality of kimchi during storage at $35^{\circ}C$. The optimum condition for heat treatment of kimchi was considered at $60^{\circ}C$ for 30 min. Irradiation after kent treatment was effective to inhibit the growth of microorganisms and prevent the quality change of kimchi during storage. In particular, microorganisms of kimchi co-treated with heat and 20 kGy-irradiation were not detected and sensory scores of that were the highest after storage at $35^{\circ}C$ for 14 days. Therefore, combination treatment of heat and irradiation was considered as the effective method to improve the shelf-stability of kimchi in the accelerated condition.

• Journal of Radiation Protection and Research
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• v.26 no.3
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• pp.249-253
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• 2001

Neutron dose assessment in criticality accidents using Whole Body Counter (WBC) was proved to be an effective method as rapid neutron dose estimation at the JCO criticality accident in Tokai-mura. The 1.36MeV gamma-ray of $^{24}Na$ in a body can be detected easily by a germanium detector. The Minimum Detectable Activity (MDA) of $^{24}Na$ is approximately 50Bq for 10miniute measurement by the germanium-type whole body counter at JNC Tokai Works. Neutron energy spectra at the typical shielding conditions in criticality accidents were calculated and the conversion factor, whole body activity-to-organ mass weighted neutron absorbed dose, corresponding to each condition were determined. The conversion factor for uncollied fission spectrum is 7.7 $[(Bq^{24}Na/g^{23}Na)/mGy]$.

• Radiation Oncology Journal
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• v.9 no.2
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• pp.361-367
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• 1991

This paper on the status of radiotherapy machine and related facilities, clinical activities and radiation safety management is based on the statistical data which collected through the questionaire sent to a total number of 37 hospitals holding the Department of Therapeutic Radiology in Korea. It is true that the quality of instruments installed in the hospitals equal to that of the instrument in the industrialized conuntries' hospitals. But the clinical specialists and physicists who can utilize such instruments fall short of the required number, which might be a main factor in hindering the development of therapeutic radiology of Korea. According to the nation-wide cancer statistics, we can estimate the number of annual cancer patients as 45,000 to 50,000. As a result, probably around 25,000 should receive radiation therapy. It is expected that in the future the number of cancer patients to whom radiation therapy should be applied will become twice as much as that of the cancer patients in 1990. Given such a condition, the problem facing the Korean Society of Therapeutic Radiology now is to increase the number of medical doctors and physicists.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.4
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• pp.281-289
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• 2015

Information on sunshine duration and solar radiation are indispensable to the understanding of crop growth and development. Yet, relevant variables are not available in the Korea Meteorological Administration's (KMA) digital forecast. We proposed the methods of estimating sunshine duration and solar radiation based on the 'sky condition' of digital forecast products and validated using the observed data. The sky condition values (1 for clear, 2 for partly cloudy, 3 for cloudy, and 4 for overcast) were collected from 22 weather stations at 3-hourly intervals from August 2013 to July 2015. According to the observed relationship, these data were converted to the corresponding amount of clouds on the 0 to 10 scale (0 for clear, 4 for partly cloudy, 7 for cloudy, and 10 for overcast). An equation for the cloud amount-sunshine duration conversion was derived from the 3-year observation data at three weather stations with the highest clear day sunshine ratio (i.e., Daegwallyeong, Bukgangneung, and Busan). Then, the estimated sunshine hour data were used to run the Angstrom-Prescott model which was parameterized with the long-term KMA observations, resulting in daily solar radiation for the three weather stations. Comparison of the estimated sunshine duration and solar radiation with the observed at those three stations showed that the root mean square error ranged from 1.5 to 1.7 hours for sunshine duration and from 2.5 to $3.0MJ\;m^{-2}\;day^{-1}$ for solar radiation, respectively.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.3 no.1
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• pp.38-43
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• 2017

Tc-99m labeled sestamibi ($^{99m}Tc$-MIBI) is one of most widely used radiopharmaceuticals for myocardial SPECT imaging. Radiolabeling of $^{99m}Tc$-MIBI is recommended by heating in $100^{\circ}C$ water bath for 15 min. However, the water bath might be a source of contamination. Thus, if radiolabeling of $^{99m}Tc$-sestamibi can be performed at room temperature, then it would be more convenient to use in clinical application. In this study, we performed the radiolabeling of $^{99m}Tc$-MIBI in different temperature conditions or using different instruments to find out the efficient labeling condition. We studied the $^{99m}Tc$-MIBI labeling at room temperature or $100^{\circ}C$ heating block, and checked the labelling yields every 1 min for 10 min using radio-TLC with 2 different eluents-saline and acetone. From the experiment, we confirmed that the $^{99m}Tc$-MIBI can be labeled over 90% yield but not completed at room temperature. However, the $^{99m}Tc$-MIBI labeling was completed when it was performed in the $100^{\circ}C$ heating block. Finally, we proved that heating is essential for complete $^{99m}Tc$-MIBI labelling, furthermore using heating block is also possible instead of water bath.

• Progress in Medical Physics
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• v.9 no.4
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• pp.201-206
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• 1998

IMRT optimization method on multiple slice has been developed by using gradient based algorithm. On about 10-30 CT slices including treatment region of a patient, dose optimization has been performed slice by slice to meet the condition that each organ should be exposed below maximum tolerable doses and that the tumor dose within the range of 100$\pm$5 %. Field size was limited to 8$\times$8 cm$^2$ and in this condition, beam divergence was not taken into account to calculate dose distribution. Total dose distribution was calculated by superposing each beamlet whose dose distribution had been precalculated. In order to investigate beam number dependency, dose optimization was performed for one, three, five, seven, and nine coplanar beams and then each optimization index was evaluated. It is found that optimization time was proportional to number of slices to be optimized, and the most efficient plan was obtained from the case of three-to-seven incident beams with respect to calculation time and optimization index. In conclusion, dose optimization of multiple slice was able to be obtained by repeating dose optimization of single slice under condition that the beam size is not too large to ignore beam divergence. And it turns out that result of dose optimization was so sensitive to the position of isocenter that some method to optimize isocenter position is needed to improve it.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.105-110
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• 2011

The objective of this study is to analyze the characteristic of radiation environment in the urban and rural through the field observation in the summer. The radiation balance was compared through the measurement of the shortwave radiation and long-wave radiation in the urban, sub-urban, and rural. The following conclusion could be obtained from this research. (1) In the results of observation including the rain-day, it was found that the short wave radiance in the urban is lower about 10% than the rural. (2) The upper part of atmosphere layers in the urban area absorb much short wave radiation energies compared with the rural relatively. It can increase the temperature of the upper part of atmosphere layers and the emittance of long wave radiation. (3) The ratio of the downward short wave radiation to the downward long wave radiation was 1.24 for the urban, 1.28 for sub-urban and1.35 for rural. It can be estimated that the atmosphere condition of the rural is better than that of other areas.

• Journal of the Korean Solar Energy Society
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• v.22 no.4
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• pp.35-43
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• 2002

This research makes that quantitative radiation property of an actual town ward is obtained in quest of the parameter with regard to a radiation heat transfer property and set up several town ward models that reproduced a solid form of a city along the attribute of the city. A regular trend possibility that is able to evaluate a radiation characteristics of a town ward quantitatively from a town ward guideline and confirmation that is produced about each parameter as a result of a numerical value simulation it obtained. This research shot a coefficient of Gebhart's emission absorption. sky radiation absorption rate direct solar radiation absorption rate the parameter with regard to a radiation heat transfer characteristics of a town ward in each town ward model and a volume rate of a town ward advances case study under regular such condition and shot the absorption rate, direct and others days and calculated an absorption rate and checked about the relation between a town ward and each radiation heat transfer property of a city.