• 펄프종이기술
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• 제42권3호
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• pp.43-49
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• 2010

Recently, the use of fumigants for pest control of paper cultural heritages are limited because of the high toxicity of fumigants and the production of environment-harmfully compounds. Therefore, many non-chemical methods have been discussed and experimented. And it is recently focused on gamma radiation, which is one of non-chemical methods, for pest control of paper cultural heritage in Korea. In this paper, we carried out a gamma ray irradiation of papers including Hanji, copy paper, filter paper and then analyzed a physical properties and optical properties of paper sample to estimate the effect of gamma ray irradiation on paper properties. In result, gamma radiation have adverse effect on a physical properties and optical properties of paper, especially Hanji. Therefore, we have to carefully consider about using of gamma ray for pest control of paper cultural heritages.

• 대한방사선치료학회지
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• 제9권1호
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• pp.50-55
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• 1997

The optimal management of uveal melanoma is still a matter of controversy. To determine the effect of Gamma Knife surgery for patients with uveal malanoma. the authors reviewed the results of 5 patients underwent Gamma Knife sugery between Sep. 1993 and Dec. 1996. The mean age was 60.7 years ranging from 42.5 to 76.5 years. Median follow-up was 13.29 months and the patient with follow up period more than 6 months was 4. The mean tumor volume was $3442 mm^3$(mean diameter 15.3 mm) and all patients were irradiated with a mean maximum dose of 74Gy(range $60\~80\;Gy$), using the $50\%$ isodose. After Gamma Knife surgery. one pateint showed complete disapperance in tumor size with follow-up 32 months, one enucleation due to progression, and 2 no interval change. In regard to vision, one patient blind. one enucleation, and 2 patients had no interval change. According to our experiences, Gamma Knife surgery for uveal melanoma be able to achieve local tumor control, spare the eyeball, and have possibility of save vision.

• Archives of Pharmacal Research
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• 제28권3호
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• pp.343-350
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• 2005

Gamma radiation causes suppression of the immune function, and immune properties are related to cytokine production. In the present study, the polysaccharide, Ginsan, purified from an ethanol-insoluble fraction of Ginseng (Panax ginseng C.A. Meyer, Araliaceae) water extract was studied to assess its effects on the immunosuppressive activities of gamma radiation. Gin­san was found to stimulate murine normal splenocytes by inducing the mRNA expressions of Th1 and Th2 type cytokines, and also restore the mRNA expression of IFN-$/gamma$, Th1 cytokine, after its inhibition by whole-body gamma irradiation. Therefore, Ginsan was found to restore the T lymphocytes function that had been suppressed by gamma irradiation in allogenic MLR (mixed lymphocyte reactions). However, Ginsan exhibited no excessive stimulatory effects on the control group. The above results indicated that Ginsan may constitute a new noble agent for the improvement of gamma radiation-induced immunosuppression.

• 한국의학물리학회지:의학물리
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• 제32권1호
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• pp.18-24
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• 2021

Purpose: Kilovoltage computed tomography (kV-CT) is essential for radiation treatment planning. However, kV-CT images are significantly distorted by artifacts when a metallic prosthesis is present in the patient's body. Thus, the accuracies of target delineation and treatment dose calculation are inevitably lowered. We evaluated the accuracy of the calculated doses using an image restoration method with hybrid CT, which was introduced in our previous study. Methods: A cylindrical phantom containing four metals, namely, silver, copper, tin, and tungsten, was scanned using kV-CT and megavoltage CT to produce hybrid CT images. We created six verification plans for three head and neck patients on kV-CT and hybrid CT images of the phantom and calculated their doses. The actual doses were measured with film patches during beam delivery using tomotherapy. We used the gamma evaluation method to compare dose distribution between kV-CT and hybrid CT with three gamma criteria, namely, 3%/3 mm, 2%/2 mm, and 1%/1 mm. Results: The gamma pass rates decreased as the gamma criteria were strengthened, and the pass rate of hybrid CT was higher than that of kV-CT in all cases. When the 1%/1 mm criterion was used, the difference in gamma pass rates between them was up to 13%p. Conclusions: According to our findings, we expect that the use of hybrid CT can be a suitable approach to avoid the effect of severe metal artifacts on the accuracy of dose calculation and contouring.

• 방사선산업학회지
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• 제5권3호
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• pp.253-258
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• 2011

Acetylsalicylic acid (ASA) has been issued recently in contaminated water environments because of potential impacts on ecosystem and public health. This study was aimed at investigating the possibility of ASA degradation using gamma ray irradiation. In addition, the use of sodium persulfate, hydrogen peroxide, ferrous sulfate were tested in order to examine a synergistic effect with gamma ray. The absorbed dose was ranged from 0.2 to 10 kGy and the concentration of oxidants were from 0.1 to 10 mM in this study. The concentration of ASA was gradually decreased corresponding to the increase of the absorbed dose. When soudium persulfate was simultaneously applied, most of the parent compound was completely degraded even at a low dose of 0.8 kGy. The removal efficiency of total organic carbon was 90% even at the highest dose of 10 kGy without sodium persulfate. However, the efficiency was dramatically enhanced up to 98% at the same dose by adding 10 mM of oxidants. It was suggested that hydroxyl radical ($OH{\cdot}$) and sulfate radical ($SO{_4}^-{\cdot}$) were formed in the system and made roles in degrading ASA at the same time.

• 환경생물
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• 제20권3호
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• pp.197-204
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• 2002

저선량 $\gamma선 조사가 참박의 초기생육과 생리활성에 미치는 효과를 알아보기 위하여 참박 종자에 $\gamma선을 0-2O Gy 수준으로 조사하여 생육을 관찰하였다. 저선량 $\gamma선에 의한 참박의 초기생육은 대조구에 비해 4-16Gy에서 다소 증가하였고, 생육 조사시 측정한 자엽의 경우 catalase와 Peroxidase 활성이 대조구에 비해 8 Gy 조사구에서 가장 높았으며 본엽은 peroxidase활성이 4 Gy 조사구에서 확연히 증가하였다. 저선량 $\gamma선을 조사한 박 식물체의 광 스트레스에 대한 반응효과는 광계II의 광화학적 효율이 대조구와 8 Gy의 경우 50% 정도 감소되었으나 4 Gy에서는 40% 정도의 감소를 보였다. 반면 Fo는 광저해가 진행됨에 따라 약간의 증가를 보였으나 대조구나 저선량 조사구사이의 차이는 거의 없는 것으로 나타났다. 광계II의 광양자 수율, $\varphi_{PSII}$과 광계II 반응중심의 흥분 포획능, 1/Fo-l/Fm 또한 광저해가 진행되는 동안 감소하여 $\varphi_{PSII}$는 대조구와 8 Gy의 경우 20% 정도 감소를 보인 반면 4 Gy 조사구는 15%의 감소를 보였고, 1/Fo-lF/m은 대조구와 8 Gy는 55%, 4 Gy는 45%의 감소를 나타냈다. 비광화학적 소멸인 NPQ는 대조구와 저선량 조사구 모두 70% 정도 감소되는 경향을 보였다. 이러한 결과를 볼 때 종자의 종피를 투과한 저선량의 $\gamma선이 참박의 생육을 촉진시키고 4 Gy에서 광 스트레스에 대한 저해가 감소되었다.

• 방사선산업학회지
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• 제2권3호
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• pp.105-110
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• 2008

Poly (VDF-co-HFP)/PEGDMA nanofibrous membranes (NFMs) have been prepared by an electrospinning process. Since electrospun NFMs have a nanoporous structure, they have a potential application for a polymer electrolyte or a separator. Poly (VDF-co-HFP) is a polymer electrolyte binder. In order to improve their mechanical properties, poly (VDF-co-HFP)/PEGDMA NFMs were crosslinked by a gamma-ray irradiation. Then the crosslinked NFMs were characterized through an electrolyte uptake, IR structural analysis, and SEM morphological investigation.

• Journal of Ceramic Processing Research
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• 제20권4호
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• pp.363-371
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• 2019

In this study, physical properties of normal concrete, magnetite concrete, EAF concrete, and EAF concrete with added iron powder were evaluated and a feasibility of radiation shielding is also evaluated through irradiation tests against X-rays and gamma-rays. While the unit weight of EAF concrete (3.21 t/㎥) appeared lower than that of magnetite concrete (3.50 t/㎥), the results in compressive strength of EAF concrete were greater than those in magnetite and normal concrete. While the radiation transmission rate of normal concrete reaches 26.0% in the X-ray irradiation test, only 6.0% and 9.0% of transmission rate were observed in magnetite concrete and linear relationship with unit volume weight and radiation shielding. In the gamma-ray irradiation test, the performance of EAF and magnetite concretes appeared to be similar. Through the results on the excellent physical properties and radiation shielding performance a potential applicability of EAF concrete to radiation shielding was verified.

• Journal of Radiation Protection and Research
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• 제47권4호
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• pp.214-225
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• 2022

Background: The conventional cerium-doped Gd₂Al₂Ga₃O₁₂ (GAGG(Ce)) scintillator-based gamma-ray imager has a bulky detector, which can lead to incorrect positioning of the gammaray source if the shielding against background radiation is not appropriately designed. In addition, portability is important in complex environments such as inside nuclear power plants, yet existing gamma-ray imager based on a tungsten mask tends to be weighty and therefore difficult to handle. Motivated by the need to develop a system that is not sensitive to background radiation and is portable, we changed the material of the scintillator and the coded aperture. Materials and Methods: The existing GAGG(Ce) was replaced with Bi₄Ge₃O₁₂ (BGO), a scintillator with high gamma-ray detection efficiency but low energy resolution, and replaced the tungsten (W) used in the existing coded aperture with lead (Pb). Each BGO scintillator is pixelated with 144 elements (12 × 12), and each pixel has an area of 4 mm × 4 mm and the scintillator thickness ranges from 5 to 20 mm (5, 10, and 20 mm). A coded aperture consisting of Pb with a thickness of 20 mm was applied to the BGO scintillators of all thicknesses. Results and Discussion: Spectroscopic characterization, imaging performance, and image quality evaluation revealed the 10 mm-thick BGO scintillators enabled the portable gamma-ray imager to deliver optimal performance. Although its performance is slightly inferior to that of existing GAGG(Ce)-based gamma-ray imager, the results confirmed that the manufacturing cost and the system's overall weight can be reduced. Conclusion: Despite the spectral characteristics, imaging system performance, and image quality is slightly lower than that of GAGG(Ce), the results show that BGO scintillators are preferable for gamma-ray imaging systems in terms of cost and ease of deployment, and the proposed design is well worth applying to systems intended for use in areas that do not require high precision.

• 한국환경농학회지
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• 제24권1호
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• pp.66-70
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• 2005

The experiment was carried out to investigate the effects of gamma radiation on the early growth performance and physiological traits of BT2 clone tea, the most promising cultivar released by Bangladesh Tea Research Institute. The fresh shoot cuttings were irradiated with seven different levels of gamma radiation such as 0, 10, 20, 30, 40, 50 and 60 Gy from Cobalt 60Co source (Dept. of PlantBreeding, Bangladesh Institute of Nuclear Agriculture). Thereafter, the irradiated shoot cuttings were planted in polythene bags and kept under natural conditions. It was observed that callusing was initiated from 8th weeks after placement of tea shoot cuttings in the polythene bags and completed by 12th weeks. The morphological growth of tea shoot cuttings were recorded under varying levels of gamma radiation and growth stages. It was observed that the number of leaves, number of primary branches, base diameter, root length and total leaf area per plant significantly increased with the progress of time and increasing levels of gamma radiation, however, the plant height showed decreasing trend with the increasing levels of gamma radiation, which could be due to the change in chromosomal structure and genetic makeup. After 56 weeks of planting, the plant height, the number of leaves and primary branches per plant, base diameter, root length and total leaf area per plant recorded were 65.70 cm, 30.67, 7.33, 1.48 cm, 23.50 cm, and 1250.67 cm2 per plant respectively under the radiation level 60 Gy, whereas the corresponding figures of the above parameters at the control treatment were 76.21 cm, 18.33, 3.67, 0.92 cm, 17.75 cm and 778.33 cm2 per plant, respectively. A significant relationship was observed among the physiological growth parameters with the increasing levels of gamma radiation. The total dry matter gain, leaf area index, absolute growth rate and relative growth rate were significantly influenced with the rising levels of gamma radiation (up to 60 Gy), whereas the net assimilation rate of individual tea plant non-significantly responded as compared to those of control treatment. Finally after 56 weeks of planting, the maximum total dry weight gain, leaf area index, absolute growth rate, relative growth rate and net assimilation rate recorded under 60 Gay radiation level were 40.25 g/plant/week, 4.25, 1.18 g/week, 0.0621g/g/week and 17.07 g/m2/week respectively.