• 한국식품영양과학회지
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• 제27권2호
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• pp.291-295
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• 1998

The ovalbumins obtained from hen's and duck's egg white were irradiated with up to 100 kGy at room temperature. The purified proteins were evaluated for their in vitro digestibility by incubating successively with pepsin and pancreatin conjugate. Amino acid compositions and SDS-PAGE pattern in these proteins were also analyzed. The obtained results indicated that gamma irradiation within the tested dose range(up to 100kGy) produced no statistically significant changes in the in vitro digestibility an amino acid compositions. Analysis of gamma-irradiated ovalbumins by SDS-PAGE revealed radiolysis of ovalbumin into proteins or peptides of low molecular weights.

• Food Science and Biotechnology
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• 제17권1호
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• pp.58-65
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• 2008

To see the possibility of irradiation as an alternative to ultra high temperature (UHT) sterilization, the quality characteristics of milk were analyzed. Milk treated by UHT ($135^{\circ}C$ for 4 sec) and irradiation at higher than 3 kGy showed no viable counts after 7 days of storage at $4^{\circ}C$. The contents of certain amino acids of milk, such as Arg, Asp, Glu, Ile, Leu, Lys, Pro, Ser, Thr, and Tyr, were lower in irradiated groups at 10 kGy than in UHT-treated one, but no difference was observed between irradiated milks at less than 5 kGy and UHT. The capillary electrophoresis (CE) patterns of the milk irradiated at 10 kGy showed a similar trend to the raw milk, low temperature long time (LTLT, $63^{\circ}C$ for 30 min), and high temperature short time (HTST, $72^{\circ}C$ for 15 sec) treated. However, the CE pattern of UHT-treated milk was different. Rennet coagulation test agreed with the CE results, showing that all milk samples were coagulated by rennet addition except for UHT-treated milk after 1 hr. These results suggest that irradiation of milk reduce the content of individual amino acids but it may not induce severe conformational change at a protein level when compared with UHT treatment.

• ETRI Journal
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• 제27권4호
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• pp.449-452
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• 2005

The electrical characteristics of solid state devices such as the bipolar junction transistor (BJT), metal-oxide semiconductor field-effect transistor (MOSFET), and other active devices are altered by impinging photon radiation and temperature in the space environment. In this paper, the threshold voltage, the breakdown voltage, and the on-resistance for two kinds of MOSFETs (200 V and 100 V of $V_{DSS}$) are tested for ${\gamma}-irradiation$ and compared with the electrical specifications under the pre- and post-irradiation low dose rates of 4.97 and 9.55 rad/s as well as at a maximum total dose of 30 krad. In our experiment, the ${\gamma}-radiation$ facility using a low dose, available at Korea Atomic Energy Research Institute (KAERI), has been applied on two commercially available International Rectifier (IR) products, IRFP250 and IRF540.

• 한국식품과학회지
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• 제5권2호
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• pp.129-135
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• 1973

미강유에 미치는 방사선 조사의 영향과 이에 따른 변화를 연구하기 위하여 용매 추출한 미강유에 B.H.T, C.A. 를 각각 0.01% 첨가, 공기 존재하에서 2 Mrads와 7 Mrads의 두가지 선량으로 dose rate 300 rads/sec 인 $^{60}Co-gamma$ (25,000 Ci) 선원을 조사직후 $5^{\circ}C$와 $25^{\circ}C$에서 저장하여 경시적으로 A.V., P.O.V., C.O.V.를 측정하여 얻은 결과는 다음과 같다. 1) A.V.는 저장 중 온도차, 항산화제의 첨가 유무에 관계없이 조사에 의한 상승이나 감소는 별로 없었다. 2) P.O.V.는 저장 중 계속 증가하는 것이 아니고 증감의 반복을 유지하면서 즉 과산화물의 생성과 분해가 일어나면서 증가했다. 3) C.O.V.는 P.O.V.가 증가하면 감소하는 결과를 보여 P.O.V.와 다른 경향을 나타 냈으며 7주에서는 거의 일정하거나 변화가 없었다. 4) 항산화제는 2 Mrads 조사에서는 B.H.T.가 C.A.보다 항산화력이 좋았으나, 7 Mrads 에서는 별 차이를 보이지 않았고, 장기저장면에서 보면 조사후에 항산화제를 첨가하는 것이 효과적임을 알 수 있다. 5) 조사선량에 따른 영향에 있어서, 시료의 처리조건 (저장온도, 항산화제의 첨가등)에 관계없이 일율적으로 2 Mrads 로 조사된 시료의 P.O.V. 가 높았다. 6) 고온 저장$(25^{\circ}C)$은 저온 저장$(5^{\circ}C)$때 보다 P.O.V.의 상승이 2배였으며, 8주저장중 저온에서는 1주 P.O.V.의 2배의 상승을, 고온에서는 $3{\sim}4$ 배로 상승하여 역시 저온 저장이 효과적임을 알 수 있다.

• 전기학회논문지
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• 제57권5호
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• pp.803-807
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• 2008

A making process of DSC(dye sensitized solar cell) was presented. In general, Photo electrodes of DSC was made by using colloid paste of nano $TiO_2$ and processing of Doctor-blade printing and high temperature sintering for porous structure. These methods lead to cracks on $TiO_2$ surface and ununiform of $TiO_2$ thickness. This phenomenon is one factor that makes low efficiency to cells. After $TiO_2$ printing on TCO glass, a physical vibration was adapted for reducing ununiform of $TiO_2$ thickness. And a thermal treatment at low temperature(under $75^{\circ}C$) was adapted for reducing cracks on $TiO_2$ surface. In this paper, we have designed and manufactured an ultrasonic circuit (100W, frequency and duty variable) and a thermal equipment. Then, we have optimized forcing time, frequency and duty of ultrasonic irradiation and thermal heating for surface treatment of photo-electrode of DSC. In I-V characteristic test of DSC, ultrasonic and thermal treated DSC shows 19% improved its efficiency against monolithic DSC. And it shows stability of light-harvesting from drastically change of light irradiation test.

• Progress in Superconductivity
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• 제3권1호
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• pp.36-40
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• 2001

We have studied vortex dynamics in$ Bi_2$$Sr_2$$CaCu_2$O$_{8}$single crystals of unirradiated and irradiated samples by using 100 $\times$ $100\mu\textrm{m}^2$Hall sensor. Doses equivalent magnetic fields are 20 G, 100 G and 1 kG. In the magnetization measurement, a second magnetization peak (SMP) was observed in unirradiated, 20 G dose and 100 G dose samples in contrast to 1 kG dose sample. In the unirradiated sample, the SMP was observed in the range of 18 K ~ 35 K and the amplitude of the SMP decreased with increasing temperature. With increase of the irradiation dose, temperature region and sharpness of the SMP were reduced. In the magnetic relaxation measurement, we observed that the normalized relaxation rate S decreased with increasing the irradiation dose. Our results suggest that the vortex dynamics is not greatly affected by low-density columnar defects.s.

• 한국분말재료학회지
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• 제30권5호
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• pp.431-435
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• 2023

An irradiation hardening of Inconel 718 produced by selective laser melting (SLM) was studied based on the microstructural observation and mechanical behavior. Ion irradiation for emulating neutron irradiation has been proposed owing to advantages such as low radiation emission and short experimental periods. To prevent softening caused by the dissolution of γ' and γ" precipitates due to irradiation, only solution annealing (SA) was performed. SLM SA Inconel 718 specimen was ion irradiated to demonstrate the difference in microstructure and mechanical properties between the irradiated and non-irradiated specimens. After exposing specimens to Fe³⁺ ions irradiation up to 100 dpa (displacement per atom) at an ambient temperature, the hardness of irradiated specimens was measured by nano-indentation as a function of depth. The depth distribution profile of Fe³⁺ and dpa were calculated by the Monte Carlo SRIM (Stopping and Range of Ions in Matter)-2013 code under the assumption of the displacement threshold energy of 40 eV. A transmission electron microscope was utilized to observe the formation of irradiation defects such as dislocation loops. This study reveals that the Frank partial dislocation loops induce irradiation hardening of SLM SA Inconel 718 specimens.

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

• 소성∙가공
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• 제8권3호
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• pp.241-241
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• 1999

With the aim of assessing the degradation of Zr-2.5Nb pressure tubes operating in the Wolsong unit-1 nuclear power plant, characterization tests are being conducted on irradiated Zr-2.5Nb tubes removed after 10-year operation. The examined tube had been exposed to temperatures ranging from 264 to 306℃ and a neutron fluence of 8.9×$10^{21}$ n/cm²(E>1 MeV) at the maximum. Tensile tests were carried out at temperatures ranging from RT to 300℃. The density of a-type and c-type dislocations was examined on the irradiated Zr-2.5Nb tube using a transmission electron microscope. Neutron irradiation up to 8.9×$10^{21}$ n/cm²(E>1 MeV) yielded an increase in a-type dislocation density of the Zr-2.5Nb pressure tube to 7.5×$10^{14} m^{-2}$, which was highest at the inlet of the tube exposed to the low temperature of 275℃. In contrast, the c-component dislocation density did not change with irradiation, keeping an initial dislocation density of 0.8×$10^{14} m^{-2}$ over the whole length of the tube. As expected, the neutron irradiation increased mechanical strength by about 17-26% in the transverse direction and by 34-39% in the longitudinal direction compared to that of the unirradiated tube at 300℃. The change in the mechanical properties with irradiation is discussed in association with the microstructural change as a function of temperature and neutron fluence.

• Journal of Electrochemical Science and Technology
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• 제13권3호
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• pp.390-397
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• 2022

The use of microwaves as the energy source for synthesis and sintering of ceramics offers substantial advantages compared to conventional gas-fired and electric resistance furnaces. Benefits include much shorter processing times and reaching the sintering temperature more quickly, resulting in superior final product quality. Most oxide ceramics poorly interact with microwave irradiation at low temperatures; thus, a more complex setup including a susceptor is needed, which makes the whole process very complicated. This investigation pursued a new approach, which enabled us to use microwave irradiation directly in poorly coupled oxides. In many solid-state electrochemical devices, the support is either metal or can be reduced to metal. Metal powders in the support can act as an internal susceptor and heat the entire cell. Then sufficient interaction of microwave irradiation and ceramic material can occur as the sample temperature increases. This microwave heating and exothermic reaction of oxidation of the support can sinter the ceramic very efficiently without any external susceptor. In this study, yttria stabilized zirconia (YSZ) and a Ni-YSZ cermet support were used as an example. The cermet was used as the support, and a YSZ electrolyte was coated and sintered directly using microwave irradiation without the use of any susceptor. The results were compared to a similar cell prepared using a conventional electric furnace. The leakage test and full cell power measurement results revealed a fully leak-free electrolyte. Scanning electron microscopy and density measurements show that microwave sintered samples have lower open porosity in the electrode support than conventional heat treatment. This technique offers an efficient way to directly use microwave irradiation to sinter thin film ceramics without a susceptor.