• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.20 no.1
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• pp.39-48
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• 2024

Research reactors are operated under ambient temperature and atmospheric pressure, which is much less severe conditions compared to those in typical nuclear power plants. Due to the high temperature, heat resistant materials such as austenite stainless steel should be used for the reactors in typical nuclear power plants. Whereas, as the effect of temperature is low for research reactors, materials with high resistance to neutron irradiation, such as zircaloy and beryllium, are used. Therefore, these conditions should be considered when performing integrity assessment for research reactors. In this study, a computational technique through finite element (FE) analysis was developed considering the operating conditions and materials of research reactor when conducting integrity assessment. Neutron irradiation analysis techniques using thermal expansion analysis were proposed to consider neutron irradiation growth and swelling in zirconium alloys and beryllium. A user subroutine program that can calculate the strain rate induced by neutron irradiation creep was developed for use in the commercial analysis program Abaqus. To validate the proposed technique and the user subroutine, FE analysis results were compared with hand-calculation results, and showed good agreement. Consequently, developed technique and user subroutine are suitable for evaluating structural integrity of research reactors.

• The Korean Journal of Ceramics
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• v.6 no.1
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• pp.6-8
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• 2000

The specific heat of a partly deuterated triglycine selenage (DTGSe) crystal under $\gamma$-irradiation was measured. It was shown that $\gamma$-irradiation defects changed the thermodynamic behavior of DTGSe crystal in a small dose region. The order of the phase transition changed from the first to the second at D=0.3 MR.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 1997.04a
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• pp.40-40
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• 1997

• Journal of Photoscience
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• v.9 no.2
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• pp.217-220
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• 2002

Ultraviolet B (UVB) radiation may activate or deteriorate cultured human epidermal melanocytes, depending on the doses and culture conditions. In this study, we examined whether apoptosis of melanocytes can be induced by physiologic doses of UVB irradiation. PI staining for DNA condensation and flow cytometric analyses demonstrated the apoptotic cell death of melanocytes after UVB irradiation. The level of p53 and Bax revealed a dose-dependent increase with increasing dose of UVB, but the level of Bcl-2 remained unchanged. Confocal microscopic examination showed that Bax moved trom a diffuse to a punctate distribution after UVB irradiation. However, there were no changes in the pattern of Bcl-2. We next examined the downstream targets of apoptosis. Our results showed that a precursor form of caspase-3 disappeared with increasing doses of UVB. We also observed cleavage of poly(ADP-ribose) polymerase (PARP) after UVB irradiation. In addition, UVB irradiation resulted in a remarkable activation of c-Jun N-terminal kinase (JNK). These results indicate that UVB may induce apoptosis via JNK activation in human melanocytes.

• Preventive Nutrition and Food Science
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• v.7 no.3
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• pp.323-326
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• 2002

Ionizing radiation can be used to sanitize herbs contaminated by various microorganisms. However, health concerns related to irradiation damage to complex molecules in plants necessitate that methods be developed to monitor such damage. To elucidate DNA damage of herbs caused by irradiation, the DNA comet assay was used for Astragalus membranaceus Bunge and Havenia dulcis Thumb, irradiated at 1, 5, 7, and 10 kGy. With increasing irradiation doses, the tails of comets became longer with average tail length increasing from 17 (non-irradiated) to 124 (10 kGy) $\mu$m in Astragalus membranaceus Bunge. Above 7 kGy, some of the tails were separated from the heads of comets. Distribution patterns of the tail length of In comets selected randomly in the irradiated herbs were analyzed to quantify the DNA damage. These results clearly suggest that the DNA comet assay is an effective and inexpensive tool for the detection of irradiation damage to DNA in herbs.

• Journal of Environmental Health Sciences
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• v.21 no.3
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• pp.102-106
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• 1995

This study was performed to examine factors affecting the decompostion of nondegradable polluants(trichloroethylene(TCE), phenol) using ultrasonic irradiation. The TCE and phenol, which are major hazard compounds causing environmental pollution, were not decomposable pollutants by conventional treatment. The results show that the oxidation and reduction reaction of ultrasound produced $H_2O_2$, $H^+$ and $OH^-$ radical, which decomposed pollutants of TCE and phenol in water. It was confirmed that the ultrasonic irradiation showed an excellent removal efficiency for the nondegradable pollutants than any other processes, utilized in the treatment of organic compounds in the industrial wastewater. Conclusively, these results suggest that ultrasonic irradiation may be highly useful for the treatment of wastewaters contaminated organic pollutants, which is difficult to treat economically by conventional process.

• Korean Journal of Veterinary Research
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• v.15 no.1
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• pp.9-13
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• 1975

In oder to investigate the effects of cobalt-60 gamma irradiation on the postnatal body gains and the other influece of the pregnant mice were subjected to single whole-body gamma irradiation externally. The results obtained were as follows: 1. The all mice of 400, 600, and 800 Rads gamma-irradiated groups showed abortion after prenatal gamma irradiation within 4 to 9 days. 2. There were significant differences of the postnatal body gains of mice between the control and treated groups (100 Rads and 200 Rads gamma irradiation). 3. The relation between gamma-irradiated doses and the postnatal growth rates of mice were inversly proportional.

• Analytical Science and Technology
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• v.27 no.1
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• pp.27-33
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• 2014

This study described about preparation of the cross-linked silk fibroin (SF) film by ${\gamma}$-irradiation of the casted SF film, which is fabricated from aqueous solution regenerated via fibers of cocoons and their application as supports for human cell culture. The properties of cross-linked SF film were evaluated by FT-IR spectroscopy, contact angle, solubility to water, thermal analysis, surface area analyzer, and morphology via scanning electron microscopy (SEM). The cross-linked SF films were not dissolved in water and exhibited the rough surface morphology, large surface area, and good thermal properties. The human fibroblast cell (CCD-986sk) and embryo kidney-ft cell were well growed on the surface of cross-linked SF film supports prepared by ${\gamma}$-irradiation. The cross-linked SF film prepared by ${\gamma}$-irradiation can be used as biomaterials for human cell culture.

• Nuclear Engineering and Technology
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• v.49 no.7
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• pp.1472-1482
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• 2017

Zirconium alloy cladding tube specimens were irradiated at $380^{\circ}C$ up to a fast neutron fluence of $7.5{\times}10^{24}n/m^2$ in a research reactor to investigate the effect of neutron irradiation on hydride reorientation and mechanical property degradation. Cool-down tests from $400^{\circ}C$ to $200^{\circ}C$ under 150 MPa tensile hoop stress were performed. These tests indicate that the irradiated specimens generated a smaller radial hydride fraction than did the unirradiated specimens and that higher hydrogen content generated a smaller radial hydride fraction. The irradiated specimens of 500 ppm-H showed smaller ultimate tensile strength and plastic strain than those characteristics of the 250 ppm-H specimens. This mechanical property degradation caused by neutron irradiation can be explained by tensile hoop stress-induced microcrack formation on the hydrides in the irradiation-damaged matrix and subsequent microcrack propagation along the hydrides and/or through the matrix.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1651-1654
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• 2006

Field emission (FE) currents were measured for silver-pasted and glass-pasted single-walled carbon nanotubes (SWNTs) after illuminating the tubes with a pulsed 532 nm laser. A very low turn-on field of approximately 0.4 V/m m and a high current density ~1700 $\mu A/cm^2$ at 3.5 V/m m was obtained for the silver-pasted SWNTs after laser irradiation but on the whole, no improvements were found for the glass-pasted SWNTs. Two roles of laser irradiation for the silver-pasted SWNTs were proposed. First, the embedded SWNTs and SWNT bundles inside the silver paste were immerged on the outer surface due to an instantaneous melting or annealing of the silver metals by the laser resulting in an increase of the field emission sites. Second, the laser irradiation was thought to improve the electrical contact between SWNTs and the silver metal by reducing the contact resistance via laser-induced thermal annealing, which was responsible for increasing the FE currents.