• 한국포장학회지
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• 제27권2호
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• pp.85-90
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• 2021

The gamma irradiation was on to Poly(butylene sebacate-co-terephthalate) (PBSeT), Poly(butylene adipate-co-terephthalate) (PBAT), Poly(lactic acid) (PLA) and casting polypropylene (CPP) at dose levels from 0 to 50 kGy. The properties of gamma irradiated samples were analyzed using DSC, TGA, UTM and FT-IR spectra. The mechanical and thermal properties of PBSeT and PBAT after gamma irradiation were less affected than CPP. The tensile strength and elongation of PBSeT was not affected by gamma irradiation, while these of PBAT, PLA and CPP were significantly decreased at 50 kGy gamma-ray dose. The thermal stability of PBSeT, PBAT, PLA and CPP showed a similar tendency to tensile strength. The glass transition temperature(T_g) and melting temperature(T_m) of PBSeT and PBAT were not altered by increasing gamma-ray dose, while these of PLA and CPP decreased. The chemical composition of all samples was not modified by gamma irradiation, and it was confirmed by FT-IR spectra. Based on mechanical and thermal stability studies of gamma irradiation on bioplastics, tested biodegradable packaging materials showed a potential to be used in sterilization process up to 35 kGy.

• Nuclear Engineering and Technology
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• 제45권7호
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• pp.941-950
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• 2013

The Korean Nuclear-Hydrogen Technology Development (NHTD) Plan will be performing irradiation testing of coated particle fuel at HANARO to support the development of VHTR in Korea. This testing will be carried out to demonstrate and qualify TRISO-coated particle fuel for use in VHTR. The testing will be irradiated in an inert gas atmosphere without on-line temperature monitoring and control combined with on-line fission product monitoring of the sweep gas. The irradiation device contains two test rods, one has nine fuel compacts and the other five compacts and eight graphite specimens. Each compact contains about 260 TRISO-coated particles. The irradiation device is being loaded and irradiated into the OR5 hole of the in HANARO core from August 2013. The device will be operated for about 150 effective full-power days at a peak temperature of about $1030^{\circ}C$ in BOC (Beginning of Cycle) during irradiation testing. After a peak burn-up of about 4 atomic percentage and a peak fast neutron fluence of about $1.7{\times}10^{21}\;n/cm^2$, PIE (Post-Irradiation Examination) of the irradiated coated particle fuel will be performed at IMEF (Irradiated Material Examination Facility). This paper reviews the design of test rod and irradiation device for coated particle fuel, and discusses the technical results for irradiation testing at HANARO.

• Bulletin of the Korean Chemical Society
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• 제35권10호
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• pp.2969-2973
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• 2014

A new process to fabricate a composite LSCF-Ag cathode material for SOFCs by electron beam (e-beam) irradiation process has been suggested for operation under intermediate temperature range of $600-700^{\circ}C$. A composite LSCF-Ag cathode with uniformly coated Ag nanoparticles on the surface of the LSCF material was prepared by a facile e-beam irradiation method at room temperature. The morphology of the composite LSCF-Ag material was analyzed using a TEM, FE-SEM, and EDS. The prepared composite LSCF-Ag material can play a significant role in increasing the electro-catalytic activities and reducing the operating temperature of SOFCs. The performance of a tubular single cell prepared using the composite LSCF-Ag cathode, YSZ electrolyte and a Ni/YSZ anode was evaluated at reduced operating temperature of $600-700^{\circ}C$. The micro-structure and chemical composition of the single cell were investigated using a FE-SEM and EDS.

• Nuclear Engineering and Technology
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• 제44권5호
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• pp.543-550
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• 2012

The decrease in the fracture toughness of ferritic steels in a reactor pressure vessel is an important factor in determining the lifetime of a nuclear power plant. A surveillance program has been in place in Korea since 1979 to assess the structural integrity of RPV steels. In this work, the surveillance data were collected and analyzed statistically in order to derive the empirical relationship between the embrittlement and strengthening of irradiated reactor pressure vessel steels. There was a linear relationship between the yield strength change and the transition temperature shift change at 41 J due to irradiation. The proportional coefficient was about $0.5^{\circ}C$/MPa in the base metals (plate/forgings). The upper shelf energy decrease ratio was non-linearly proportional to the yield strength change, and most of the data lay along the trend curve of the US results. The transition regime temperature interval, ${\Delta}T_T$, was less than the US data. The overall change from irradiation was very similar to the US results. It is expected that the results of this study will be applied to basic research on the multiscale modeling of the irradiation embrittlement of RPV materials in Korea.

• 방사선산업학회지
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• 제7권1호
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• pp.23-28
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• 2013

In this study, we fabricated high density polyethylene (HDPE) composites filled with antioxidants and UV stabilizers. The electron beam irradiation on the fabricated composites was carried out over a range of absorbed doses from 50 to 200 kGy to confirm the changes of discoloration. The changes of discoloration were characterized using a color difference meter and FT-IR for confirming the changes of the color difference and structural change. It was observed that the color difference of IRGANOX 1010-, IRGAFOS 168-, and TINUVIN 328- added HDPE was higher than that of the control HDPE by electron beam irradiation. The melting temperature of UV stabilizer-added HDPE was not significantly changed by electron beam irradiation. However, the melting temperature of phenol-containing antioxidant-added HDPE was increased with increasing the absorbed dose. And the melting temperature of phosphorus-containing antioxidant-added composite was decreased with increasing the absorbed dose.

• 한국축산식품학회지
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• 제35권3호
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• pp.406-412
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• 2015

The combined effects of electron-beam irradiation and ageing of beef were examined. The irradiated samples at dose of 0 or 2 kGy were kept and analyzed for the microbial growth, shear values, meat color, and nucleotide-related flavor compounds at different ageing temperatures (2, 10, or 25℃) for 8 d. The irradiation effect on inactivation of foodborne pathogens was also investigated. The population of Listeria monocytogenes and E. coli O157:H7 inoculated in beef samples decreased in proportion to the irradiation dose, showing D₁₀ values of 0.66 and 0.65 kGy respectively. The irradiated beef eye of round had lower number of total aerobic bacteria (TAB) than nonirradiated one during the storage, but the TAB increased with higher ageing temperature (p<0.05). Especially, TAB increased sharply in non-irradiated samples aged at 25℃ after 4 d (p<0.05). With increasing ageing temperature and ageing time, shear force values decreased (p<0.05). The color a* values of the irradiated beef were lower than those of the non-irradiated throughout the ageing period (p<0.05). As ageing time and temperature increased, the amounts of inosine monophosphate decreased and the hypoxanthine increased (p<0.05). Relatively high ageing temperature could be used at irradiated beef eye of round to shorten the ageing time.

• The Journal of Korean Physical Therapy
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• 제24권3호
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• pp.202-207
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• 2012

Purpose: The purpose of this study was to determine the effect of monochromatic infrared energy (MIRE) on the blood flow of the superficial radial artery and local skin temperature in healthy subjects. Methods: Forty healthy volunteers were recruited and randomly assigned to MIRE group (n=20) and placebo group (n=20). The MIRE group received a 890 nm MIRE irradiation on the forearm using two therapy pads for 30 minutes. The therapy pad was composed of an array of 60 diodes. MIRE unit was set at bar 8, that corresponds to a diode power of 10 mW and a power density of $63mW/cm^2$. The placebo group received sham MIRE. Peak blood flow velocity (PBFV), mean blood flow velocity (MBFV), and skin temperature (ST) were measured pre- and post-MIRE irradiation. Results: There was a significant difference in PBFV (p<0.001), MBFV (p<0.001), and ST (p<0.001) between the pre- and post-treated values in the MIRE group. In contrast, no significant difference was found between the pre- and post-treated values in the placebo group. There was significant difference in mean change values from baseline of PBFV (p<0.001), MBFV (p<0.001), and ST (p<0.001) between the MIRE group and the placebo group. There was a significant increase in PBFV (p<0.001), MBFV (p<0.001), and ST (p<0.001) following MIRE irradiation. Conclusion: The arterial blood flow and local skin temperature of the forearm in the healthy subjects were significantly increased following MIRE irradiation.

• 산업식품공학
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• 제15권1호
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• pp.28-33
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• 2011

UV-C와 -B type의 lamp를 이용한 혼합 자외선(UV)조사의 조사시간, 조사온도 및 광 촉매제인 $H_2O_2$의 분사농도변화를 이용하여 감귤껍질에 부착되어있는 농약을 제거하기 위한 공정의 최적화를 이루고자 하였다. Chloropyrifos에 대한 독립변수들의 영향력은 조사온도가 가장 컸으며 그 다음 조사시간, $H_2O_2$ 분사농도 순 이었다. Methidathion은 조사시간이 가장 컸으며 조사온도, $H_2O_2$ 분사농도 순으로 나타났다. EPN은 조사온도와 조사시간이 비슷하게 나타났고 $H_2O_2$ 분사농도가 가장 작았다. UV감귤껍질의 농약 잔존량이 가장 작게 나타난 처리조건으로 chloropyrifos와 EPN에 대한 최적조건으로는 조사시간 60분, 조사온도 $45^{\circ}C$, $H_2O_2$ 분사농도 1000 ppm으로 나타났다. 반면에 methidathion의 경우에는 최적조건으로는 조사시간 60분, 조사온도 $40^{\circ}C$, $H_2O_2$ 분사농도 1000 ppm으로 나타났다. 최적공정조건에서 chloropyrifos, methidathion 및 EPN의 잔존 량은 조사 전의 각각 46, 49 및 28% 수준이었다.

• 열처리공학회지
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• 제17권3호
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• pp.151-164
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• 2004

The changes of microstructural and mechanical properties were evaluated for the high burn-up fuel claddings after the neutron irradiation of $1.8{\sim}3.1{\times}10^{20}n/cm^2$ (E>1.0 MEV) in HANARO research reactor. After the irradiation, the spot-type dislocations (a-type dislocations) were easily observed in most claddings, and the density of the dislocations was different depending on the grains and was higher at grain boundaries than within grains. As the final annealing temperature increased, the density of spot-type dislocations increased and the line-type dislocations (c-type dislocations) which was perpendicular to the <0002> direction, appeared sporadically in some claddings. However, the types of precipitates in the fuel claddings after the irradiation were not changed from that in unirradiated claddings. The mechanical properties including the hardness, strength and elongation after the irradiation were changed due to the formation of spot-type dislocations. That is, the increase in hardness and strength as well as the decrease in elongation after the irradiation was occurred simultaneously with increasing the final annealing temperature. Owing to the Nb contribution to the formation of spot-type dislocation during the irradiation, the increase in hardness and strength in higher Nb-contained Zr alloys after the irradiation was higher than that in lower Nb-contained Zr alloys.

• Preventive Nutrition and Food Science
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• 제8권2호
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• pp.185-190
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• 2003

Gamma irradiation was used as part of a new processing method to produce a brighter-colored and mild-flavored green tea leaf extract that retained all of its physiological activities. Dried green tea leaf was extracted with 70% ethanol and gamma irradiated at 0,5, 10, 20 kGy. Hunter color $L^{*}$- and $a^{*}$-values were increased with irradiation in a dose-dependent manner, which was a color range from dark brown to bright yellow. However, the irradiation effect gradually disappeared during 3 weeks of storage, with color reverting to that of untreated samples. There was no difference in the radical scavenging and tyrosinase inhibition effect by irradiation. Among antioxidants used, ascorbic acid was the most effective against color reversion. In contrast, cysteine was shown to protect the effect of color change with irradiation. Results indicated that enhanced color of irradiated green tea leaf extract can be effectively controlled by additives such as ascorbic acid and a low storage temperature.e.e.