[en] The high-Tc RE-Ba-Cu-O superconductors have great potential for the applications using the superconductor-magnet performance such as the flywheel energy storages systems, the levitation transportation, the superconducting permanent magnets, and so on. To realized the practical applications at the high magnetic fields, the brittleness of the oxide superconductors owing to the complicated crystal structure should be improved. In this study, metallic Ag powder was added to Gd1.5Ba2Cu3O7-y(Gd1.5) bulk superconductors with an aim of improving the mechanical properties of the oxide superconductors. The Tcs of the Gd1.5 with Ag additions were 93 K, which are slightly lower than 93.5 K of the Gd1.5 without Ag addition. The Jcs of the Gd1.5 with 5-20 wt.% Ag additions at 1 Tesla were similar to that of the Gd1.5 with no Ag addition. The Jc of Gd1.5 decreased as the Ag content increased further. The Fms and the Hs of the Gd1.5 with Ag additions also showed a similar tendency to the Tc and Jc. For example, the Fm of the Gd1.5 with 15 wt.% Ag addition was approximately 80% of the Gd1.5 without Ag addition. The property decrease by the Ag addition seems to be attributed to the reduced volume fraction of Gd123 due to the presence of non-superconducting Ag particles inside Gd123 grains and the formation of the subsidiary G123 grains due to the seed(Nd123) melting and recrystallization, which prohibits the growth of the single Gd123 grain. The vickers hardness estimated on the polished surfaces parallel to the a-b plane of Gd123 grains was observed to decrease linearly with as Ag content increased. The fracture toughness values calculated from the hardness data showed that the fracture toughness were increased by the Ag additions

[en] To compare and characterize distinctive features of the involvement pattern of hypertrophic olivary degeneration, focusing on its various causes and the extent of hemorrhage. In 15 patients (M:F=10:5; age range, 39-66 years) with hypertrophic olivary degeneration, the MR imaging findings were retrospectively reviewed. Signal intensity and changes in the size of the olivary nucleus were recorded, focusing on the causes of the condition and the extent of hemorrhage and involvement, as seen on T2-, proton density-weighted, and FLAIR images. The findings of follow-up study were available in three cases. In three patients with substantial hemorrhaging in the central portion of the pons or midbrain, bilateral hypertrophic olivary degeneration was observed, and in one with a large infarction in the pons, bilateral degeneration was revealed by MR images obtained three months later. In nine cases of unilateral hemorrhage of the pons or midbrain, unilateral hypertrophic olivary degeneration was present, and in one case of unilateral hemorrhage in the dentate nucleus, degeneration was contralateral. In one case of central hemorrhage in the pons and midbrain, bilateral degeneration was noted initially, and a fuzzy margin and increased high signal intensity of the olivary nucleus were noted on T2-weighted images obtained at follow-up nine months later. Contrast enhanced T1-weighted images depicted on definite enhancement. Hypertrophic olivary degeneration arises as secondary change due to phenomena such as hemorrhage or infarction, and shows variable patterns according to its causes

[en] This study was to compare the intake and Committed Effective Dose(CED) due to inhalation of I-131. The intake and CED calculations were based on KIDAC, LUDEP, MONDAL and IMBA computer codes

[en] Periodic safety review(PSR) is considered to be the measure to obtain overall view of actual plant safety, to determine necessary of worthwhile change that should be made in order to maintain a high level of safety and to improve the safety of older nuclear power plant(NPP) to level comparison with that of modern plants. According to the nuclear power law, PSR must be applied to operating NPPs. Evaluation item for PSR is composed of 11 factors in NPP's laws of Korea. The object of radiation safety performance that one between 11 factors is to determine whether radiation safety performance in a NPP is to identify changing inclination through investigation and analysis relevant to records of radiation dose and radioactive effluents. The object of this paper is to review whether NPP laws associated with radiation protection could be applied to PSR report. For this purpose, domestic NPP laws related on PSR was investigated and comparison with items of PSR report

[en] At nuclear power plants the radioiodines of principal interests are I-131, associated with reactor operations, especially after defected fuels. After releasing from the defected fuel to working area, I-131 is considered the significant radionuclide from an internal exposure. This paper is to compare and calculate the dosimetric model and committed effective dose(CED) based on international commission on radiological protection's publication 30/54 and 66/78

[en] According as the annual public dose limit was adjusted 5mSv to 1mSv based on ICRP-60, the radioactive materials for the gaseous and liquid released from nuclear power plant to environment should be controlled properly under public dose limit. The surveillance of the radiological effluent in PHWR NPPs is more important than PWR. Since the gaseous effluent has been released continuously and the amount of radiological effluent is relatively more than that of PWR. In this study, DRLs(Derived Release Limits) for gaseous effluent were preliminarily calculated using the ECL(Effluent Concentration Limit) and the system method based on ICRP-60 recommendation and notification No. 2002-1 of Ministry Of Science and Technology. As a result, the calculated DRL of the gaseous tritium using the ECL and system method was reduced within approximate 30% and 20% of existing limit, respectively

[en] Both tritium and carbon-14 represent the radioactive isotopes that may bring about internal exposure to the workers for PHWRs. Therefore, it is necessary to obtain detailed information on the metabolism of tritium and carbon-14 in order to reasonably evaluate radiation reduction and dose assessment. This study herewith compared with the relevant information from both domestic and abroad each other, so as to establish a metabolism model of tritium and carbon-14 in human body for Korean

[en] Nanosized SrFe₂O₄ powders were prepared by precipitation followed by reaction at the moderate temperature and pressure. Nanosized SrFe₂O₄ powders were obtained by reaction at 200 deg C for 6 h. The average size of synthesized particles was in the range of 5 to 20 nim and the phase of synthesized particles was crystalline. The magnetic character of the synthesized SrFe₂O₄ particles was superparamagnetic. The effects of pH of starting solution is discussed. Copyright (2003) AD-TECH - International Foundation for the Advancement of Technology Ltd

[en] Social concerns over radiation safety remain a very important issue in the management of nuclear power plants and the installation of facilities for radiation waste storage. To understand how environmental effects of radionucleus from radiation facilities relate to human beings, the development of an unmanned monitoring system is required. The IAEA suggests a method to evaluate the effects of radiation emitted from radiation facilities on marine water, freshwater, and habitats for land animals and plants on its Technical Report Series 190 , 288, and 332. Recently, (IAEATECDOC- 1270, 2002), ICRP Publication No. 91 (2003) was consecutively published to protect nonhuman animals and plants from environmental radiation and radioactive materials. In particular, ³H and ¹⁴C, types of radionuclides that are emitted from nuclear power plants, are mostly emitted from heavy-water reactor and ³H also from light-water reactor to affect surrounding environments (Jeong et al. 2005). As these radionuclides exist in nature and become the major cause of environmental exposure (Koarashi et al. 2005; Levin et al. 1988), we need to have an accurate understanding of their dynamic movements to evaluate the surrounding environments of radiation facilities. Nevertheless, not many studies have been done on this topic. This study sets up the following requirements to select a biological indicator: 1) it must be an animal species that is clearly classified from other species (Cobert 1978); 2) it must have a consistent ecological characterization; 3) it must inhabit areas that are also livable for humans; 4) its habitat must be limited; 5) it must eat and drink from its habitat; 6) it must have a considerable length of lifespan; and 7) it must provide information on the radioactivity of natural radionuclides in its bodies (Mihok et al. 1989). This study compared the external appearances and enzyme types in the livers of dark-striped field mice to classify them and only selected middle-aged mice to measure the radionuclides in their whole bodies and each organ

[en] Synaptic plasticity can be mimicked by electronic synaptic devices. By using ferroelectric thin films as gate insulator for thin-film transistors (TFT), channel conductance can be defined as the synaptic plasticity, and gradually modulated by the variations in amounts of aligned ferroelectric dipoles. Poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)]-poly(methyl methacrylate) (PMMA) blended films are chosen and their switching kinetics are investigated by using the Kolmogorov-Avrami-Ishibashi model. The switching time for ferroelectric polarization is sensitively influenced by the amplitude of applied electric field and volumetric ratio of ferroelectric beta-phases in the P(VDF-TrFE)-PMMA films. The switching time of the P(VDF-TrFE) increases with decreasing the pulse amplitude and/or the ratio of ferroelectric beta-phases by incorporation of PMMA. The activation electric field is also found to increase as the increase in blended amount of PMMA. Synapse TFTs are fabricated using the P(VDF-TrFE)-PMMA as gate insulator and In-Ga-Zn-O active channels. The drain currents of the synapse TFTs gradually increased when the voltage pulse signals with given duration are repeatedly applied. This suggests that the synaptic weights can be modulated by the number of external pulse signals, and that the proposed synapse TFT can be applied for mimicking the operations of bio-synapses. (paper)