• Journal of Radiation Protection and Research
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• v.35 no.3
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• pp.99-104
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• 2010

The potential ability of environmental temperature to enhance the effect of microwave radiation (7 GHz) was experimentally studied for rabbit heating after simultaneous application of both agents. The tested ambient temperatures (30 and $38^{\circ}C$) didn't exert a considerable influence upon rabbit heat homeostasis after the used duration of exposure (3 hours and 15 minutes, correspondingly). The synergistic interaction of microwave irradiation and ambient temperature was demonstrated for rabbit heating. Power flux density of microwave irradiation was shown to be a determinant of the synergistic interaction effectiveness. For the fixed ambient temperature ($30^{\circ}C$), the synergism was shown to be observed only within a definite power flux density ($0-100\;mW{\cdot}cm^{-2}$), inside of which there was an optimal intensity ($20\;mW{\cdot}cm^{-2}$), which maximized the synergistic effect. Any deviation of the power flux density from the optimal value resulted in a reduction of the synergy. It is concluded that any assessment of the health or environmental risks should take into account the synergistic interaction between ambient temperature and microwave radiation.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.39-49
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• 2013

The effect of the finite substrate size on the radiation characteristics of H-plane linear microstrip array antennas is investigated. The radiation characteristics versus scan angle are systematically analyzed for 5-element H-plane linear array antennas with various substrate sizes and element spacings for the substrates with different dielectric constants. The distance between the antenna center and the substrate edge on the E-plane for the enhancement of the radiation characteristics of the array antenna is presented.

• Journal of Radiation Protection and Research
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• v.43 no.1
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• pp.20-28
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• 2018

Background: Heat energy produced in nuclear reactors and nuclear fuel cycle facilities interactions modifies the physical properties of the shielding materials containing water content. Therefore, in the present paper, effect of the heat on shielding effectiveness of the concretes is investigated for gamma and neutron. The mass attenuation coefficients, effective atomic numbers, fast neutron removal cross-section and exposure buildup factors. Materials and Methods: The mass attenuation coefficients, effective atomic numbers, fast neutron removal cross-section and exposure buildup factors of ordinary and heavy concretes were investigated using NIST data of XCOM program and Geometric Progression method. Results and Discussion: The improvement in shielding effectiveness for photon and reduction in fast neutron for ordinary concrete was observed. The change in the neutron shielding effectiveness was insignificant. Conclusion: The present investigation on interaction of gamma and neutron radiation would be very useful for assessment of shielding efficiency of the concrete used in high temperature applications such as reactors.

• Journal of Mechanical Science and Technology
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• v.18 no.7
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• pp.1203-1212
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• 2004

The purpose of this study is to predict and understand the hydrodynamic forces and their nonlinear behaviors of fluid motion around the submerged plate oscillating near a free surface. To achieve this objective, we have developed a composite grid method for the solution of a radiation problem. The domain is divided into two different grids; one is a moving grid system and the other is a fixed grid system. The moving grid is employed for the body fitted coordinate system and moves with the body. This numerical method is applied to calculation of radiation forces generated by the submerged plate oscillating near a free surface. In order to investigate the characteristics of the radiation forces, the forced heaving tests have been performed with several amplitudes and different submergences near a free surface. These experimental results are compared with the numerical ones obtained by the present method and a linear potential theory. As a result, we can confirm the accuracy of the present method. Finally, the effect of nonlinear and viscous damping has been evaluated on the hydrodynamic forces acting on the submerged plate.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1619-1626
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• 2017

Electronic components that are used in high-level radiation environment require a semiconductor device having a radiation-hardened characteristic. In this paper, we proposed a radiation-hardened I-gate n-MOSFET (n-type Metal Oxide Semiconductors Field Effect Transistors) using a layout modification technique only. The proposed I-gate n-MOSFET structure is modified as an I-shaped gate poly in order to mitigate a radiation-induced leakage current in the standard n-MOSFET structure. For verification of its radiation-hardened characteristic, the M&S (Modeling and Simulation) of the 3D (3-Dimension) structure is performed by TCAD (Technology Computer Aided Design) tool. In addition, we carried out an evaluation test using a $Co^{60}$ gamma-ray source of 10kGy(Si)/h. As a result, we have confirmed the radiation-hardened level up to a total ionizing dose of 20kGy(Si).

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.123-125
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• 2002

Blue light of Cherenkov radiation generated by electrons in transparent substances such as water and acrylic resin is well known generally. If students can easily observe the blue light at school, they may be impressed by the fascinating radiation. Four years ago, management of the Co-60 unit for radiotherapy was transferred to Nagoya University School of Health Sciences from a related hospital. We have examined whether or not the Cherenkov radiation in water from secondary electrons generated by Co-60 gamma-rays can be safely observed by eyes and photographs. First, the Cherenkov radiation in the water tank was led to the corridor outside the irradiation room by a mirror, and observed directly without any effect of the radiation exposure. Second, photographs of the Cherenkov radiation were taken under the conditions consisted of several irradiation fields and pass lengths of gamma-rays in water.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.18
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• pp.7559-7562
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• 2014

Currently the most important prognostic factor in lung cancer is the stage. In the current lung TNM classification system, N category is defined exclusively by anatomic nodal location though, in other type of tumours, number of lymph nodes is confirmed to be a fundamental prognostic factor. Therefore we evaluated the number of mediastinal lymph nodes as a prognostic factor in locally advanced NSCLC after multimodality treatment, observing a significant effect of the number of lymph nodes in terms of OS (p<0.01) and DFS (p<0.001): patients with a low number of positive mediastinal nodes have a better prognosis.

• International Journal of Aeronautical and Space Sciences
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• v.3 no.1
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• pp.95-104
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• 2002

Numerical solution of the full Navier-Stokes equation as well as the energy equation has been obtained for the unsteady natural convection in a rectangular enclosure. One side wall was maintained at very high temperature simulating fires. Especially the effect of surface radiation was taken into account. While the enclosed air was assumed to be transparent, the internal walls directly interacted one another through the surface radiation. Due to a significant temperature difference in the flow field, the equation of state was used instead of the Boussinesq approximation. It was found that the rapid heating of the adiabatic ceiling and floor by the incoming radiation from the hot wall made the evolution at thermo-fluid field highly unstable in the initial period. Therefore, the secondary cells brought about at the floor region greatly affected the heat transfer mechanism inside the enclosure. The heat transfer rate was augmented by the radiation, resulting in requiring less time for the flow to reach the steady state. At the steady state neglecting radiation two internal hydraulic jumps were clearly observed in upper/left as well as in lower/right comer. However, the hydraulic jump in the lower/right comer could not be observed for the case including radiation due to its high momentum flow over the bottom wall. Radiation resulted in a faster establishment of the steady state phenomena.

• Journal of Radiation Industry
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• v.12 no.4
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• pp.349-353
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• 2018

Metronidazole (MD), which is used as an antibiotic, is largely used as an oral and skin application agent, and has inhibiting effect on the production of the fungus causing malodor. However, the maximum drug inclusion concentration is 0.75% of skin ointment in commercially available. In this study, hydrogels containing high concentration of metronidazole were prepared by using radiation crosslinking technique based on biocompatible polymers, and release characteristics and antimicrobial properties were evaluated. This study was preliminary carried out to investigate whether it could be used effectively as antibacterial dressing materials.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.620-622
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• 2022

When an optical fiber is exposed to radiation, a color center is formed in the core, which lowers the optical transmittance of the optical fiber. This is called the radiation-induced attenuation(RIA), and research on optical fibers having improved radiation resistance by changing materials and structures is being actively conducted. This is because radiation-resistant optical fibers have the advantage that they can be used in telecommunication and optical applications even in extreme environments such as space and nuclear power plants. In this paper, the effect of gamma irradiation of commercial radiation-resistant optical fibers was analyzed.