• 방사선산업학회지
• /
• 제5권1호
• /
• pp.41-46
• /
• 2011

Polyacrylonitrile (PAN) fibers are the most widely used precursor of the materials for carbon fibers. The conventional process of carbon fibers from PAN precursor fiber includes two step; stabilization at low temperature and carbonization at high temperature. Compared to thermal stabilization, the stabilization process by electron beam (E-beam) irradiation is a advanced and brief method. However, a stabilization by E-beam irradiation was required a high dose (over 5,000 kGy) and spend over 1.5 hr (1.14 MeV, 1 mA). In the present work the main goal is exploring a quick stabilization process by cotrolling E-beam currents. The effect of various E-beam currents on stabilization of PAN precursor fiber was studied by gel fraction test, thermo gravimertic analysis (TGA), differential scanning calorimetry (DSC), tensile strength, and scanning electron microscopy (SEM) images.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2002년도 추계학술발표강연 및 논문개요집
• /
• pp.33-33
• /
• 2002

• 방사선산업학회지
• /
• 제6권3호
• /
• pp.267-272
• /
• 2012

This study evaluated the change in anti-allergy activity of ${\beta}-glucan$ by electron beam irradiation. ${\beta}-Glucan$ was irradiated at dose of 50 kGy and then orally pre-treated with electron beam irradiated and non irradiated ${\beta}-Glucan$ for 7 days. After pre-treatment, allergy was induced by injection of ovalbumin (OVA). Serum total immunoglobulin E (IgE) and OVA-specific IgE levels in the allergic mice was significantly increased but the mice pre-treated 50 kGy electron beam irradiated ${\beta}-glucan$ was significantly decreased the levels of total IgE and OVA-specific IgE, respectively. Moreover, cytokine production (interleukin-4) was also decreased in the 50 kGy electron beam irradiated ${\beta}-Glucan$ pre-treated mice. These results indicate that pre-treatment of 50 kGy electron beam irradiated ${\beta}-glucan$ may elevate the anti-allergy activity. Therefore, electron beam-irradiated ${\beta}-glucan$ could be used for nutraceutical foods in food industry.

• 농업과학연구
• /
• 제39권3호
• /
• pp.341-347
• /
• 2012

The objective of this study was to investigate the combined effect of electron beam irradiation (EB) and onion peel extracts and selected flavorings on microbiological and sensory quality of pork jerky. Total aerobic bacteria were detected in the range of $3.87{\pm}0.30{\sim}4.60{\pm}0.12$ log CFU/g in all samples. Addition of both onion peel extract and flavoring showed the decrease of total aerobic bacterial count in pork jerky. No viable cells were observed after EB at 4 kGy. Sensory evaluation indicated that the EB-treated pork jerky with 0.5% barbecue flavoring did not show any difference in overall acceptability compared with the control. Therefore, combined use of EB with onion peel extracts and barbecue flavoring may enhance the safety of pork jerky with proper sensory quality.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1995년도 추계학술대회 논문집
• /
• pp.293-297
• /
• 1995

In order to investigate the electrical properties of Transformer Oils, Volume Resistivity for transformer oils was made researches. in this paper, the specimen was produced by irradiation of electron beam, which is divided by the dose, 12[Mrad], 24[Mrad], 36[Mrad]. By investigating the electrical properties of dielectric liquid due to the difference of electron beam irradiation the effect of electron beam irradiation was studied. To measure the physcial properties of transformer Oils, Fourier transfer infrared spectroscopy was investigated. And the study for the electrical properties of dielectric liquid was made by measuring volume resistivity of specimen. the Electrode for the measuring Volume resistivity is formed coaxial cylindrical shape, and its geometric capacitance is confirmed to 16[pF]. In this experiments, Highmegohm meter which is model VMG-1000, was used for the measuring volume resistivity. the applying voltages were DC 100, 250, 500, 1000[V] in the temperature range of 20∼120[$^{\circ}C$]. By means of the result from this experiment the movement of carrier and the physcial constants to contribute dielectric properties is introduced.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 D
• /
• pp.1416-1418
• /
• 1998

In this paper, the physical and electrical conduction properties due to the electron beam irradiation for low density polyethylene using insulating materials of the distribution cable and ultra-high voltage cable are studied. In FTIR spectrum for physical properties, the strong absorptions by methyl groups in wavenumbers 720[$cm^{-l}$] and 1463[$cm^{-l}$] are observed, and the effect by residual carbonyl groups (C = 0) is hardly appeared. So, as a result of the electrical conduction properties, it is confirmed that the conduction current is increased nearly to 50[$^{\circ}C$], and is not changed until the crystalline melting point from the temperature over 60[$^{\circ}C$] because of the defects of morphology and the formation of many trap centers by means of electron beam irradiation.

• 접착 및 계면
• /
• 제6권4호
• /
• pp.12-17
• /
• 2005

Natural fiber/phenolic biocomposites with chopped henequen fibers treated at various levels of electron beam irradiation (EBI) were made by means of a matched-die compression molding method. The interfacial property was explored in terms of interfacial shear strength measured by a single fiber microbonding test. The thermal properties were studied in terms of storage modulus, tan ${\delta}$, thermal expansion and thermal stability measured by dynamic mechanical analysis, thermomechanical analysis and thermogravimetric analysis, respectively. The result showed that the interfacial and thermal properties depend on the treatment level of EBI done to the henequen fiber surfaces. The present result also demonstrates that 10 kGy EBI is most preferable to physically modify the henequen fiber surfaces and then to improve the interfacial property of the biocomposite, supporting earlier results studied with henequen/poly (butylene succinate) and henequen/unsaturated polyester biocomposites.

• 방사선산업학회지
• /
• 제4권4호
• /
• pp.359-364
• /
• 2010

PVDF-HFP (binder)/silylated alumina (inorganic particle)-coated PE (polyethylene) separators were with various compositions of binder and inorganic particle were prepared by a dip-coating process with humidity control (R.H. 25% and 50%) using electron beam irradiation. The morphology of the coated PVDF-$HFP/Al_2O_3$ layer with various compositions of PVDF-HFP and $Al_2O_3$, and humidity condition was found to be an important factor in determining ionic conductivity of the prepared separators. The PVDF-$HFP/Al_2O_3$ (5/5)-coated PE separator prepared at R.H. 50% followed by electron beam irradiation at 200 kGy was applied for lithium-ion polymer battery and the cell test results showed improved high-rate discharge performance and better cyclic stability compared to the cells with the bare PE and the PVDF-HFP-coated PE separators.

• 한국의학물리학회지:의학물리
• /
• 제34권3호
• /
• pp.33-39
• /
• 2023

Purpose: FLASH radiotherapy (RT) using ultra-high dose rate (>40 Gy/s) radiation is being studied worldwide. However, experimental studies such as preclinical studies using small animals are difficult to perform due to the limited availability of irradiation devices and methods for generating a FLASH beam. In this paper, we report the initial dosimetry results of a prototype electron linear accelerator (LINAC)-based irradiation system to perform ultra-high dose rate (UHDR) preclinical experiments. Methods: The present study used the prototype electron LINAC developed by the Research Center of Dongnam Institute of Radiological and Medical Sciences (DIRAMS) in Korea. We investigated the beam current dependence of the depth dose to determine the optimal beam current for preclinical experiments. The dose rate in the UHDR region was measured by film dosimetry. Results: Depth dose measurements showed that the optimal beam current for preclinical experiments was approximately 33 mA, corresponding to a mean energy of 4.4 MeV. Additionally, the average dose rates of 80.4 Gy/s and 162.0 Gy/s at a source-to-phantom surface distance of 30 cm were obtained at pulse repetition frequencies of 100 Hz and 200 Hz, respectively. The dose per pulse and instantaneous dose rate were estimated to be approximately 0.80 Gy and 3.8×10⁵ Gy/s, respectively. Conclusions: Film dosimetry verified the appropriate dose rates to perform FLASH RT preclinical studies using the developed electron-beam irradiator. However, further research on the development of innovative beam monitoring systems and stabilization of the accelerator beam is required.

• Journal of Biosystems Engineering
• /
• 제38권2호
• /
• pp.87-94
• /
• 2013

Purpose: Pineapple is now the third most important tropical fruit in world production after banana and citrus. Phytosanitary irradiation is recognized as a promising alternative treatment to chemical fumigation. However, most of the phytosanitary irradiation studies have dealt with physiochemical properties and its efficacy. Accurate dose calculation is crucial for ensuring proper process control in phytosanitary irradiation. The objective of this study was to optimize phytosanitary irradiation treatment of pineapple in various radiation sources using Monte Carlo simulation. Methods: 3-D geometry and component densities of the pineapple, extracted from CT scan data, were entered into a radiation transport Monte Carlo code (MCNP5) to obtain simulated dose distribution. Radiation energy used for simulation were 2 MeV (low-energy) and 10 MeV (high-energy) for electron beams, 1.25 MeV for gamma-rays, and 5 MeV for X-rays. Results: For low-energy electron beam simulation, electrons penetrated up to 0.75 cm from the pineapple skin, which is good for controlling insect eggs laid just below the fruit surface. For high-energy electron beam simulation, electrons penetrated up to 4.5 cm and the irradiation area occupied 60.2% of the whole area at single-side irradiation and 90.6% at double-side irradiation. For a single-side only gamma- and X-ray source simulation, the entire pineapple was irradiated and dose uniformity ratios (Dmax/Dmin) were 2.23 and 2.19, respectively. Even though both sources had all greater penetrating capability, the X-ray treatment is safer and the gamma-ray treatment is more widely used due to their availability. Conclusions: These results are invaluable for optimizing phytosanitary irradiation treatment planning of pineapple.