• Carbon letters
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• v.15 no.4
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• pp.262-267
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• 2014

Pyrolized fuel oil (PFO) was reformed by novel electron beam (E-beam) radiation, and the elemental composition, chemical bonds, average molecular weight, solubility, softening point, yields, and density of the modified patches were characterized. These properties of modified pitch were dependent on the reforming method (heat or E-beam radiation treatment) and absorbed dose. Aromaticity ($F_a$), average molecular weight, solubility, softening point, and density increased in proportion to the absorbed dose of E-beam radiation, with the exception of the highest absorbed dose, due to modification by free radical polymerization and the powerful energy intensity of E-beam treatment. The H/C ratio and yield exhibited the opposite trend for the same reason. These results indicate that novel E-beam radiation reforming is suitable for the preparation of aromatic pitch with a high ${\beta}$-resin content.

• Radiation Oncology Journal
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• v.10 no.1
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• pp.107-113
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• 1992

Increasing frequency of skin cancer, mycosis fungoides, Kaposi's sarcoma etc, it need to treatment dose planning for total skin electron beam (TSEB) therapy. Appropriate treatment planning for TSEB therapy is needed to give homogeneous dose distribution throughout the entire skin surface. The energy of 6 MeV electron from the 18 MeV medical linear accelerator was adapted for superficial total skin electron beam therapy. The energy of the electron beam was reduced to 4.2 MeV by a $0.5\;cm\times90\;cm{\times}180\;cm$ acryl screen placed in a feet front of the patient. Six dual field beam was adapted for total skin irradiation to encompass the entire body surface from head to toe simultaneously. The patients were treated behind the acryl screen plate acted as a beam scatterer and contained a parallel-plate shallow ion chamber for dosimetry and beam monitoring. During treatment, the patient was placed in six different positions due to be homogeneous dose distribution for whole skin around the body. One treatment session delivered 400 cGy to the entire skin surface and patients were treated twice a week for eight consecutive weeks, which is equivalent to TDF value 57. instrumentation and techniques developed in determining the depth dose, dose distribution and bremsstrahlung dose are discussed.

• Journal of the Korean Ceramic Society
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• v.42 no.2 s.273
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• pp.117-122
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• 2005

Electron Beam Physical Vapor Deposition (EB-PVD) is a typical technology for thermal barrier coating with Yttria Stabilized Zirconia (YSZ) on aero gas turbine engine. In this study EB-PVD method was used to fabricate dense YSZ film on NiO-YSZ as a electrolyte of Solid Oxide Fuel Cell (SOFC). Dense YSZ films of -10 $\mu$m thickness showed nano surface structure depending on deposition temperature. Electrical conductivities of YSZ film and electric power density of the single cell were evaluated after screen- printing $LaSrCoO_3$ as a cathode.

• Journal of Radiation Industry
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• v.9 no.1
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• pp.9-13
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• 2015

Epoxy resin is widely used as aerospace, automobile, construction and electronics due to their good mechanical and electrical properties and environmental advantages. However, the inherent flammability of epoxy resin has limited its application in some field where good flame retardancy is required. Nano clay can enhance the properties of polymers such as flames retardancy and thermal stability. In this study, we have investigated the nanoclay filled epoxy composite, which has good flame retardancy while maintaining high mechanical properties. The cured epoxy resins were obtained using an electron beam curing process. The nano clays were dispersed in epoxy acrylate solution and mechanically stirred. The prepared mixtures were irradiated using an electron beam accelerator. The composites were characterized by gel content and thermal/mechanical properties. Moreover, the flammability of the composite was evaluated by limited oxygen index (LOI). The flame retardancy of nano clay filled epoxy composite was evidently improved.

• Journal of Radiation Industry
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• v.5 no.2
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• pp.145-149
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• 2011

Poly(butylenes terephthalate) have made large strides in applications of injection, extrusion, and molding material due to their excellent thermal resistance and appropriate mechanical properties. However, PBT was not hard polymer but a soft polymer which caused low absorption of external energy and the defect of being easily broken with the strong impact. Thus, the electron beam irradiation was carried out over a range of irradiation doses from 100 to 1,000 kGy for enhancing the properties. The decreases of $T_m$, $T_c$, and enthalpy were observed as increasing the absorbed dose in the results of DSC analysis. The improvement in the impact strength of PBT was clearly observed as the absorbed dose was increased. This was probably due to the 3-dimensional network structures, resulting in increasing the absorption of impact energy. In addition, the wear properties had increased at higher than 300 kGy. The negative deviation of weight loss confirmed the improvement of the wear properties of PBT, as evidenced by SEM observation on the wear surfaces.

• Journal of Biosystems Engineering
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• v.39 no.3
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• pp.205-214
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• 2014

Purpose: Phytosanitary irradiation treatment can effectively control regulated pests while maintaining produce quality. The objective of this study was to establish the best irradiation treatment for mangosteen, a popular tropical fruit, using a Monte Carlo simulation. Methods: Magnetic resonance image (MRI) data were used to generate a 3-D geometry to simulate dose distributions in a mangosteen using a radiation transport code (MCNP5). Microsoft Excel with visual basic application (VBA) was used to divide the image data into seed, flesh, and rind. Radiation energies used for the simulation were 10 MeV (high-energy) and 1.35 MeV (low-energy) for the electron beam, 5 MeV for X-rays, and 1.25 MeV for gamma rays from Co-60. Results: At 5 MeV X-rays and 1.25 MeV gamma rays, all areas (seeds, flesh, and rind) were irradiated ranging from 0.3 ~ 0.7 kGy. The average doses decreased as the number of fruit increased. For a 10 MeV electron beam, the dose distribution was biased: the dose for the rind where the electrons entered was $0.45{\pm}0.03$ kGy and the other side was $0.24 {\pm}0.10$ kGy. Use of an electron kinetic energy absorber improved the dose distribution in mangosteens. For the 1.35 MeV electron beam, the dose was shown only in the rind on the irradiated side; no significant dose was found in the flesh or seeds. One rotation of the fruit while in front of the beam improved the dose distribution around the entire rind. Conclusion: These results are invaluable for determining the ideal irradiation conditions for phytosanitary irradiation treatment of tropical fruit.

• Korean Journal of Metals and Materials
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• v.46 no.10
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• pp.634-645
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• 2008

In this study, surface composites were fabricated with Fe-based amorphous alloy powders and VC powders by high-energy electron beam irradiation, and the correlation of their microstructure with hardness and fracture toughness was investigated. Mixture of Fe-based metamorphic powders and VC powders were deposited on a plain carbon steel substrate, and then electron beam was irradiated on these powders without flux to fabricate surface composites. The composite layers of 1.3~1.8 mm in thickness were homogeneously formed without defects and contained a large amount (up to 47 vol.%) of hard $Cr_2B$ and $V_8C_7$ crystalline particles precipitated in the solidification cell region and austenite matrix, respectively. The hardness of the surface composites was directly influenced by hard $Cr_2B$ and $V_8C_7$ particles, and thus was about 2 to 4 times greater than that of the steel substrate. Observation of the microfracture process and measurement of fracture toughness of the surface composites indicated that the fracture toughness increased with increasing additional volume fraction of $V_8C_7$ particles because $V_8C_7$ particles effectively played a role in blocking the crack propagation along the solidification cell region heavily populated with $Cr_2B$ particles. Particularly in the surface composite fabricated with Fe-based metamorphic powders and 30 % of VC powders, the hardness and fracture toughness were twice higher than those of the surface composite fabricated without mixing of VC powders.

• Journal of the Korean Society of Radiology
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• v.15 no.1
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• pp.79-83
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• 2021

In radiation therapy, electron beam is often used in the treatment of superficial lesion. Accurate measurements are required because electron beam interacts with them in the beam path and affects dose measurements. However, no research has been conducted on electron beam quality assurance. in this study, PbO-based dosimeter was fabricated as a basic study for electron beam quality assurance. Thus, the reproducibility and linearity of the energy of 6, 9, and 12 MeV were analyzed to evaluate measurement accuracy and precision. Reproducibility measurements show RSD value of 1.024%, 1.019% and 0.890%, respectively, at 6, 9, and 12 MeV. linearity measurements show 0.9999 R2 at 6, 9, and 12 MeV altogether. Both evaluations show that the PbO dosimeter has very good measurement accuracy and precision with excellent results.

• Journal of the Korean Vacuum Society
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• v.12 no.3
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• pp.182-192
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• 2003

A new Monte Carlo (MC) simulator for electron beam lithography process in the multi-layer resists and compound semiconductor substrates has been developed in order to fabricate and develop the high-speed PHEMT devices for millimeter-wave frequencies. For the accurate and efficient calculation of the transferred and deposited energy distribution to the multi-component and multi-layer targets by electron beams, we newly modeled for the multi-layer resists and heterogeneous multi-layer substrates. By this model, the T-shaped gate fabrication process by electron beam lithography in the PHEMT device has been simulated and analyzed. The simulation results are shown along with the SEM observations in the T-gate formation process, which verifies the new model in this paper.

• Journal of Radiation Industry
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• v.8 no.1
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• pp.53-57
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• 2014

The kenaf is quickly developing as a renewable resource. Kenaf can be grown under a wide range of weather conditions. Modification of kenaf fiber by graft polymerization provides a significant route to alter the chemical properties, including surface hydrophilicity or hydrophobicity. In this study, kenaf fiber surfaces were grafted with acrylic acid as a hydrophilic group using electron beam irradiation. The grafting rate increased with an increase in grafting time. The FT-IR results confirmed that acrylic acid was successfully grafted onto the kenaf fibers. The wettability of the kenaf fiber was increased, accompanied by acylic acid grafting on the fiber surface. According to the permeability test result, it was found that acrylic acid grafted kenaf fiber reinforced cement composite was more reduced than non-grafted kenaf fiber reinforced cement composite.