• Journal of Radiation Industry
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• v.5 no.3
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• pp.249-252
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• 2011

Lignin is one of the natural macromolecules. Every year large amount of lignin arises from the cellulose production as a by-product worldwide. The use of lignin as a precursor to carbonaceous materials has gained interest due to its low cost and high availability. Therefore, we improved the properties of alkali-lignin by exposing to gamma ray in this study. The alkali-lignin is irradiated by Gamma ray irradiation with varying doses. The char yields of alkali-lignin were investigated by increasing up to 50 kGy. The cross-linking and bond scission of alkali-lignin occur simultaneously during gamma ray irradiation. The crosslinking was predominantly accelerated by gamma ray irradiation up to 50 kGy. Bond scission predominantly occurs between 50 and 500 kGy. ESCA analysis indicated that the alcoholic carbon increase up to 50 kGy. Solution viscosity was increased as absorbed dose increased up to 20 kGy. In addition, the aromatic ring was not influenced by irradiation at doses ranging from 20 to 500 kGy as shown in FT-IR results.

• Journal of Sensor Science and Technology
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• v.9 no.4
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• pp.274-280
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• 2000

This paper deals with an experimental study to apply commercial semiconductors to measure radiation dose rate for gamma ray. Since the low cost, small size, high efficiency and ruggedness of silicon photodiodes make them attractive photodetectors, they coulde be effectively used in measuring any radiation such as gamma ray. Most PN photodiodes show that the reverse current increases when the light is increased. Therefore the depletion region of them have influence on the reverse current, so we choose silicon PIN photodiodes with large depletion region. In order to detect radiation dose rate and then, to apply in developing any gamma ray dosimeter, some examinations and experiments were performed to PIN photodiodes in this work. Two kinds of PIN photodiodes, such as NEC's PH302 and SIEMENS's BPW34, were tested in a Co-60 gamma irradiation facility with a semiconductor parameter analyzer. As a result, we found that such PIN photodiodes present good linearity in diode current characteristics with dose rate. Therefore silicon PIN photodiodes could be suitably used in designing gamma ray dosimeters.

• The Journal of Korean Society for Radiation Therapy
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• v.19 no.2
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• pp.91-97
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• 2007

Purpose: To evaluate the feasibility of a commercial ion chamber array for intensity modulated radiation therapy (IMRT) quality assurance (QA) was performed IMRT patient-specific QA Materials and Methods: A use of IMRT patient-specific QA was examined for nasopharyngeal patient by using 6MV photon beams. The MatriXX (Wellhofer Dosimetrie, Germany) was used for IMRT QA. The case of nasopharyngeal cancer was performed inverse treatment planning. A hybrid dose distribution made on the CT data of MatriXX and solid phantom all of the same gantry angle (0$^\circ$). The measurement was acquired with geometrical condition that equal to hybrid treatment planning. The $\gamma$-index (dose difference 3%, DTA 3 mm) histogram was used for quantitative analysis of dose discrepancies. An absolute dose was compared at the high dose low gradient region. Results: The dose distribution was shown a good agreement by gamma evaluation. A proportion of acceptance criteria was 95.8%, 97.52%, 96.28%, 98.20%, 97.78%, 96.64% and 92.70% for gantry angles were 0$^\circ$, 55$^\circ$, 110$^\circ$, 140$^\circ$, 220$^\circ$, 250$^\circ$ and 305$^\circ$, respectively. The absolute dose in high dose low gradient region was shown reasonable agreement with the RTP calculation within $\pm$3%. Conclusion: The MatriXX offers the dosimetric characteristics required for performing both relative and absolute measurements. If MatriXX use in the clinic, it could be simplified and reduced the IMRT patient-specific QA workload. Therefore, the MatriXX is evaluated as a reliable and convenient dosimeter for IMRT patient-specific QA.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.5
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• pp.1256-1260
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• 2005

The purpose of this study was to investigate the effects of Angelica gigas on jejunal survival, endogenous spleen colony formation and jejunal crypt cells of mice irradiated with Gamma-ray irradiation. The subject of this study includes 42 mice which were divided into each 7 groups. Angelica gigas experiment groups were Angelica gigas + Gamma-ray(10Gy), Angelica gigas + Gamma-ray(3Gy), Angelica gigas. Gamma-ray(1 Gy), Gamma-ray control (10Gy), Gamma-ray control(3Gy), Gamma-ray control(1Gy), Normal groups. In the present study to evaluate the effect of Angelica gigas on jejunal crypt survival, endogenous spleen colony formation, and apoptosis in jejunal crypt cells of mice Gamma-ray with each dose of Gamma-ray irradiation. The results of this study were as follows: In low-dose(1Gy) Gamma-ray radiation were treatment of Angelica gigas showed significantly increased(p<0.05) on the cell death apoptosis in crypt, intestine crypts survival of intestine after gamma-ray irradiation. High-dose(10Gy) Gamma-ray, treatment of Angelica gigas showed significantly increased(p<0.05) on the leukocyte. The above results suggest that Angelica gigas were immunostimulating effectively reduced Gamma-ray irradiation.

• Korean Journal of Environmental Biology
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• v.22 no.4
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• pp.537-542
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• 2004

To reveal the relationship between the changes in the growth and photo- synthesis induced by low dose radiation, red pepper (Capsicum annuum L.) plants were serially irradiated three times with gamma rays of 0.5, 1, 2, 3, and 4 Gy. The plant growth was monitored by the fresh weight, the stem length, and the leaf length & width. All the irradiation groups (0.5-4 Gy) were stimulated in growth at 1 day after the $1^{st}$ irradiation (DA1I), but rather inhibited at 3 days after the $3^{rd}$ irradiation (DA3I). The maximum photochemical efficiency (Fv/Fm), the photochemical quenching (qP), the non-:photochemical quenching (NPQ) and the apparent rate of the photosynthetic electron transport (ETR) were used to represent the changes in the photosynthesis by the serial irradiation. The irradiation groups except 0.5 Gy had higher Fv/Fm values at 3 DA3I than the control one. After the 3$^{rd}$ irradiation, the qP values appeared to be a little lower in the 1-4 Gy groups than in the control and 0.5 Gy ones. In contrast, the NPQ values were rather higher in the irradiation groups except 0.5 Gy. During the whole experimental period, the ETRs decreased in the control group but remained relatively constant in the 4-Gy one. In conclusion, the results obtained indicate that the stimulatory effect of ionizing radiation on the plant growth was determined by the incident dose of the single irradiation rather than by the cumulative one of the serial irradiation. They also demonstrate that the growth stimulation induced by a low dose radiation could not be positively correlated with an alteration in the photosynthesis. Additionally, we discuss in text that an ionizing radiation may partly protect the leaf senescence by delaying the development of the plants.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.324.1-324
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.1123-1124
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• 2004

• Progress in Medical Physics
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• v.28 no.1
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• pp.16-21
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• 2017

This study assessed the feasibility of a dual-channel (DC) compound method for film dosimetry. The red channel (RC) is usually used to ensure dosimetric quality using a conventional fraction dose because the RC is more accurate at low doses within 3 Gy than is the green channel (GC). However, the RC is prone to rapid degradation of sensitivity at high doses, while degradation of the GC is slow. In this study, the DC compound method combining the RC and GC was explored as a means of providing accurate film dosimetry for high doses. The DC compound method was evaluated at various dose distributions using EBT3 film inserted in a solid-water phantom. Measurements with $10{\times}20cm^2$ radiation field and $60^{\circ}$ dynamic-wedge were done. Dose distributions acquired using the RC and GC were analyzed with root-mean-squares-error (RMSE) and gamma analyses. The DC compound method was used based on the RC after correcting the GC for high doses in the gamma analysis. The RC and GC produced comparatively more accurate RMSE values for low and high doses, respectively. Gamma passing rates with an acceptance criterion of 3%/3 mm revealed that the RC provided rapid reduction in the high dose region, while the GC displayed a gradual decrease. In the whole dose range, the DC compound method had the highest agreement (93%) compared with single channel method using either the RC (80%) or GC (85%). The findings indicate that the use of DC compound method is more appropriate in dosimetric quality assurance for radiotherapy using high doses.

• KSBB Journal
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• v.26 no.6
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• pp.565-568
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• 2011

In this study, it was investigated the antioxidant activity of laminarin degraded by gamma irradiation. Because the activities of antioxidants have been attributed to various mechanisms, different assay methods have been conducted and compared. 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity, ferric reducing antioxidant power, and lipid peroxidation inhibitory activity of degraded laminarin were measured and compared with non-degraded. All of these results showed that the antioxidant activity of laminarin degraded by irradiation was increased depending on the absorbed dose. Therefore, gamma irradiation could be an alternative method for the preparation of degraded laminarin with higher antioxidant activity.

• 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].