• The Journal of the Korea Contents Association
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• v.13 no.8
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• pp.275-283
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• 2013

The patient radiation dose is different depending on selection of Ion chamber when taking Chest PA which using AEC. In this paper, we studied acquiring the best diagnostic images according to selection of Ion chamber on AEC mode as well as minimizing patient radiation dose. Experimental methods were selection of Ion chamber and change of sensitivity under the same conditions as Chest PA projection. At AEC mode, two upper ion chambers sensors and one lower ion chamber sensor were divided into 7 cases according to selection of on/off. after measuring five times respectively, we obtained average value and calculated exposure dose. Image assessment was done with measured Modulation Transfer Function, Peak Signal to Noise Ratio, Root Mean Square, Signal to Noise Ratio, Contrast to Noise Ratio, Mean to Standard deviation Ratio respectively. In exposure assessment results, selection of two upper chambers was the lowest. In resolution assessment results, image of two upper chambers had the second high spatial frequency at sensitivity at 625(High) was 1.343 lp/mm. RMS value of image selecting two upper chambers was low secondly. SNR, CNR, MSR were the high value secondly. As the sensitivity was increased, radiation dose was decreased but better image could be obtained on image quality. In order to obtain the best medical images while minimizing the dose, usage of two upper ion chambers is considered to be clinically useful at sensitivity 625(High).

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.3
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• pp.364-371
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• 2009

The effect of gamma irradiation ($0.5{\sim}2$ kGy) on the microbiological, physicochemical and sensory properties of peaches was investigated during 6 day storage at $20{\pm}3^{\circ}C$. Total aerobic bacteria, yeasts and molds significantly decreased with increasing dose level. In Hunter's color values, L-values decreased and a- and b-values increased with increment of irradiation dose level. Hardness significantly decreased with increment of irradiation dose level whereas pH, soluble solid, and total polyphenol contents increased with increment of irradiation dose level. DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging activity of irradiated peach was higher than that of control and its activity increased with increment of irradiation dose level. Vitamin C content was not affected by irradiation. In sensory test, overall acceptabilities of irradiated samples were higher than those of control. These results suggest that gamma irradiation on peach was effective for microbiological safety while improving the antioxidant activity, but not good on color and texture of peach.

• Progress in Medical Physics
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• v.21 no.2
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• pp.218-222
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• 2010

As radiation is irradiated from various directions in intensity modulated radiation therapy (IMRT), longer treatment time than conventional treatment method is taken. In case of the patients who have problem to keep same posture for long time because of pain and injury, reducing treatment time through increased dose rate is a way for effective treatment. This study measured and found out the variation of dose and dose distribution in accordance with dose rate variation. IMRT treatment plan was set up to investigate from 5 directions - $0^{\circ}$, $72^{\circ}$, $144^{\circ}$, $216^{\circ}$, $288^{\circ}$ - using ECLIPSE system (Varian, SomaVision 6.5, USA). To confirm dose and dose rate in accordance with dose rate variation, dose rate was set up as 100, 300, 500 MU/min, and dose and dose distribution were measured using ionization chamber (PTW, TN31014) and film dosimeter (EDR2, Kodak). At this time, film dosimeter was inserted into acrylic phantom, then installed to run parallel with beam's irradiating direction, 21EX-S (Varian, USA) was utilized as linear accelerator for irradiation. The measured film dosimeter was analyzed using VXR-16 (Vidar System Corporation) to confirm dose distribution.

• FLOWER RESEARCH JOURNAL
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• v.19 no.2
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• pp.119-125
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• 2011

Acorus calamus is an indigenous hydrophyte used as phytoremediation and water purification as well as medicinal herb. Irradiation of gamma ray was performed to investigate the effect on radioresistance of A. calamus on in vitro. Various doses (20-500 Gy) of gamma rays were irradiated to in vitro plantlets. The effect of irradiation was studied on survival rate, shoot formation and growth rate. The survival and multiplication rate was remarkably decreased with the increase of radiation dose. The growth of plantlets was significantly increased in comparison to the control at low doses. The hermetic effect of radiation was appeared in A. calamus. It was significantly decreased or interrupted above 250 Gy. The mean 50% lethal dose ($LD_{50}$) was extremely high as 240 Gy. We conclude that A. calamus had remarkably high radioresistance compared with other plant species.

• Journal of Korea Water Resources Association
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• v.40 no.9
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• pp.697-707
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• 2007

In this study, we estimated the PMP(Probable Maximum Precipitation) and its transition in case of the typhoon Rusa which happened the biggest damage of all typhoons in the Korea. Specially, we analysed the moisture maximizing rate under the consideration of meteorological condition based on the orographic property when it hits in Gangneung region. The PMP is calculated by the rate of the maximum persisting 12 hours 1000 hPa dew points and representative persisting 12 hours 1000 hPa dew point. The former is influenced by the moisture inflow regions. These regions are determined by the surface wind direction, 850 hPa moisture flux and streamline, which are the critically different aspects compared to that of previous study. The latter is calculated using statistics program (FARD2002) provided by NIDP(National Institute for Disaster Prevention). In this program, the dew point is calculated by reappearance period 50-year frequency analysis from 5% of the level of significant when probability distribution type is applied extreme type I (Gumbel distribution) and parameter estimation method is used the Moment method. So this study indicated for small basin$(3.76km^2)$ the difference the PMP through new method and through existing result of established storm transposition and DAD(Depth-Area-Duration). Consequently, the moisture maximizing rate is calculated in the moisture inflow regions determined by meteorological fields is higher $0.20{\sim}0.40$ range than that of previous study. And the precipitation is increased $16{\sim}31%$ when this rate is applied for calculation.

• Journal of Korean Society of Forest Science
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• v.8 no.1
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• pp.140-148
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• 1968

Ginkgo biloba L., which was distributed in Korea, was x-rayed with 100, 250, 500, 1000, 2000, 6000R. The results of responses about germination, morphological variations in seedling and early stage growth may be summarized as follows : 1. The germination percent was decreased with X-ray increasing dose from 500R except the slight stimulation of 100R. 2. The germination $LD_{50}$ seemed to be 765R. 3. The seedling height was depressed significantly but only slightly in 100R. 4. The loaf index was increased proportionally to high dose but T/R ratio was reduced apparently. 5. The dry or fresh weight decreased from 250R. It was highly significant except 100R. 6. Many morphological variations were indicated in plants.

• The Journal of the Korea Contents Association
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• v.16 no.1
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• pp.75-81
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• 2016

The recent radiation therapy field can provide treatment which guarantees a high degree of accuracy, due to patient set-up using various image guided radiation therapy(IGRT) instruments. But the additional absorbed dose to patient's normal tissues is increasing. Therefore, this study measured the absorbed dose to surrounding normal tissues which is caused by patient set-up using OBI, CBCT, ExacTrac, among various IGRT instruments. The absorbed dose to the head, the chest, the abdomen, and the pelvis from CBCT was 12.57 mGy, 20.82 mGy, 82.93 mGy, and 52.70 mGy, respectively. Also, the absorbed dose from OBI and ExacTrac ranged from 0.76 to 8.58 mGy and from 0.14 to 0.63 mGy, respectively. As a result, CBCT's absorbed dose was far higher than other instruments. CBCT's surface dose was far higher than others, too, but OBI's entrance skin dose was almost the same as CBCT's.

• Korean Journal of Environmental Biology
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• v.18 no.1
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• pp.47-51
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• 2000

Phytophthora blight of pepper, which is caused by Phytophthora capsici Leonian, is not only the most destructive disease worldwide, but also difficult to control effectively. It has been needed to have new trials for effective control to the disease. We employed radiation hormesis of gamma ray as the new trial in the control strategy. Two cultivars, Kwangbok and Dabok, were used to analyse whether gamma ray radiation can induce disease resistance. The germination rate of pepper seeds was significantly enhanced by the radiation at all dose levels. Stimulatory effect for resistance induction was found to differ between cultivars. It was confirmed that the remarkable effect was induced in Dabok and depended on radiation dosage. Disease resistance at 4 Gy was much higher than that of control. On the other hand, no detectable induction effect for resistance was observed in Kwangbok which was moderate resistant cultivar to gamma ray radiation. [Hormesis, Gamma ray, Pepper, Phytophthora blight, Resistance induction].

• Korean Journal of Environmental Biology
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• v.19 no.4
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• pp.270-277
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• 2001

To observe the stimulating effect of low dose ${\gamma}$ radiation on the dormancy breaking and growth, microtubers induced in vitro of two potato (Solanum tuberosum L. cv. Dejima and cv. Superior) cultivars with different storage duration were irradiated with ${\gamma}$ radiation at the dose of $0.5{\sim}30$ Gy. Sprouting rate, growth and tuber yield of ‘Dejima’ microtuber were increased by ${\gamma}$ radiation in the range of $2{\sim}16$ Gy. In the microtuber of ‘Superior’, the sprouting rate was promoted by 2 Gy and 4 Gy irradiation, and the growth and tuber yield by 0.5 Gy and 4 Gy irradiation. There were not that much difference in chlorophyll content of potato plantlet by the low dose ${\gamma}$ irradiation. These results suggested that low dose ${\gamma}$ radiation stimulated the dormancy breaking and potato growth.

• Journal of the Korean Society of Radiology
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• v.9 no.7
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• pp.473-478
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• 2015

Abdominal obesity is one of the most influential index to predict of insulin resistance syndrome/metabolic syndrome in social demographic characteristics. It is matter of fact that radiation dose are increasing with development of medical treatment and device. In this study, we estimated distortion between reference image and entrance surface dose when take a chest radiography forward chest phantom assumed abdominal obesity. When angle of chest phantom incline $5^{\circ}$ forward, thoracic transverse and longitudinal diameter increase 1.22% and 0.44% each. Also cardiac transverse diameter increase 1.01% and cardio-throracic ratio (CTR) decrease 0.27% in the same situation of incline to $5^{\circ}$ forward. Thoracic transverse diameter shows the largest increase, and CTR was decreased. But entrance surface dose to phantom increase significantly 6.12% when angle of chest phantom incline $5^{\circ}$ forward. In conclusion, we have to pay attention to accurate positioning, to prevent a distortion of image through incline, and make patients not to expose to additional radiation.