[en] Along the process of spectrometers construction or experimental arrangements, there are many times of difficult shielding requirements for not-strictly defined shapes, loading of internal volumes of complicated structures, very high shielding efficiency under limited volume or positions contrary to strict metallic structures of Al, Irons and steels, Cd, Pb and engineering plastics of PolyEthylene(PE) or borated PE(B-PE). We have failed to make good neutron shielding block of epoxy for those kinds of purposes for a long time but in this year we could achieve shielding blocks of epoxy having good mechanical properties and get to know many technical tips. This report describes the trials of molding and its properties for neutron shielding and mechanical properties with its related understanding. We acquired the techniques for epoxy mixing of neutron shielding materials such as B₄C, Borax, Gd₂O₃, CdS, BN, etc. And these techniques would be applied for neutron shielding purposes for neutron spectrometers and experimental configurations such as shielding blocks, bricks, beam narrowers and stoppers, and various objects of irregular shape

[en] U.S. Nuclear Regulatory Commission (US-NRC) has been reviewing the design certification application for APR1400 submitted by Korea Electric Power Corporation (KEPCO). The main concern about cold leg top slot break is that cladding temperature might be increased by core uncover due to four loop seal reformation following flooding of safety injection water. An integral effect test for cold leg top slot break was performed by KAERI (Korea Atomic Energy Research Institute) using ATLAS (Advanced Thermal-Hydraulic Test Loop for Accident Simulation), which is a scaled down experimental facility for APR1400. In this study, RELAP5/MOD3.3/Patch04 is assessed by experimental result of ATLAS cold leg top slot break. Also, thermal hydraulic phenomena by four loop seals reformation is observed by RELAP5 result. The RELAP5/MOD3.3/Patch04 is assessed by the experimental result of ATLAS cold leg top slot break. The top slot break is described by offtake model, and the mass flow rate is fairly well estimated. The RELAP5 well predicts the correlation between general trend and four loop seal reformation. The pressure of the core region and the cladding temperature tends to increase during four loop seal reformation due to steam path blockage on four loop seals. It is presumed that the code cannot estimate two phase phenomena by loop seal clearing as same as experiments. In terms of cladding temperature, loop seal reformation due to loop seal elevation of APR1400 does not need to be the issue, since the void fraction at the active top core is maintained over 0.4

[en] In this study, cold leg top slot break calculations are performed by RELAP5/MOD3.3 Patch04 for the ATLAS test which is the scaled down experimental facility for the APR1400. The test condition for base case is selected as 0.1016 m (4 in.) based on the break size of the APR1400. In addition, sensitivity studies about break size, break distance from vessel, and pressurizer location are performed until the initiation of simultaneous injection of 2.5 hours. The loop seal reformation occurs early, and the duration of final loop seal reformation is longer as the break is close to vessel. Nonetheless, PCT increased by loop seal reformation is not identified since core uncovery does not occur. In this study, it is confirmed through RELAP5 simulation of the ATLAS test that cold leg top slot break for the APR1400 is not a safety issue in perspective of the loop seal reformation.

[en] We report here on a case of extrahepatic biliary cystadenoma arising from the common hepatic duct. A 42-year-old woman was evaluated by us to find the cause of her jaundice. Ultrasonography and CT showed a cystic dilatation of the common hepatic duct and also marked dilatation of the intrahepatic duct. Direct cholangiography demonstrated a large filling defect between the left hepatic duct and the common hepatic duct; dilatation of the intrahepatic duct was also demonstrated. Following excision of the cystic mass, it was pathologically confirmed as a unilocular biliary mucinous cystadenoma arising from the common hepatic duct

[en] We wanted to evaluate the diagnostic value of the various findings on sacroiliac CT for detecting the early changes of ankylosing spondylitis (AS). Between April 2005 and March 2006, 51 sacroiliac CT images with the clinical suspicion of AS, but no definite evidence of AS on the plain radiograph only, were retrospectively reviewed. Finally, 36 patients (mean age: 28.6 years; 34 males and 2 females), who were clinically diagnosed as AS (AS group, n = 26) or they had no evidence of AS (non-AS group, n = 10), were evaluated. Two musculoskeletal radiologists analyzed the presence of marginal irregularity, bony erosion and subchondral sclerosis. A statistical analysis was performed to evaluate the incidence, sensitivity and specificity of each finding. Marginal irregularity was seen in 21 of 26 AS subjects, and in 8 of 10 non-AS subjects. Bony erosion was only seen in 13 of 26 AS subjects. Subchondral sclerosis was observed in 19 of 26 AS subjects and in 8 of 10 non-AS subjects. The sensitivity/specificity for each findings were 72.4%/28.6%, 100%/43.5% and 70.4%/22.2%, respectively. Except for bony erosions, these results showed no statistical significance (ρ = .006). Bony erosion on CT is a very sensitive finding for the early changes of AS, whereas marginal irregularity or subchondral sclerosis is not so helpful in differentiating AS from non-AS. Attention to these results may further enhance the accurate diagnosis of the early changes in AS

[en] Aberrant cervical thymus is rarely reported in adults. We report a case of solid aberrant cervical thymus in a 27 year old female, which was found incidentally on ultrasonography for the evaluation of the thyroid cancer. On ultrasonography, the lesion was found between the left thyroid and common carotid artery without any remarkable interface echo, and had similar echogenicity to the thyroid. The lesion extended to the upper pole of the left thyroid

[en] Highlights: • We fabricated bottom-gate ZnO:H TFTs using photochemical H doping. • Photochemical H doping was performed by two UV irradiations of ZnO film surface. • Electrical properties of the ZnO:H TFTs were improved with the increase in UV irradiation time. We examined the effect of photochemical hydrogen doping on the performance of ZnO thin-film transistors (TFTs). H atoms were doped into the ZnO active layers (ZnO:H) by irradiation at two different ultraviolet (UV) wavelengths, 185 and 254 nm, for 0, 2, 4, and 6 h. Then, the ZnO surface before and after H doping was analyzed using X-ray photoelectron spectroscopy and X-ray diffraction. The ZnO surface exhibited metal–OH bonding states and the oxygen vacancy increased with the UV irradiation time. In addition, the surface roughness of the ZnO thin film decreased from 1.634 to 1.385 nm because of the increasing hydrophilicity as the oxygen vacancy increased, reducing the trap sites and electron scattering at the channel/insulator interface, thus improving the TFT performance. Among the samples, the ZnO:H TFTs with 6 h of UV irradiation time exhibited the best performance, the saturation mobility increased from 1.56 to 14.2 cm²/Vs, the on/off ratio increased from 10⁵ to 1.1 × 10⁶, and the threshold voltage decreased from 5.42 to 2 V compared to the ZnO TFTs with no UV irradiation.

[en] ZnO thin film transistors (TFTs) with reduced graphene oxide (RGO)-embedded channel layers were fabricated and their electrical properties were compared with those of ZnO TFTs with no embedded layer (bare ZnO TFT), with Cr-embedded channel layers, and with a RGO/ZnO bilayer channel. Compared to the reference samples, the proposed ZnO TFTs with RGO-embedded layers exhibited very stable unipolar transfer characteristics with enhanced carrier mobility of 1.13 cm² V⁻¹ s⁻¹, subthreshold swing of 0.53 V decade⁻¹, and on/off ratio of 2.31 × 10⁷, unlike most previous reports of graphene-embedded ZnO TFTs which exhibited undesirable ambipolar behavior. These improvements are attributed to the high carrier mobility of the RGO layer and the formation of the ZnO-RGO-ZnO area as a leakage prevention barrier in the negative bias region. In addition, through X-ray photoelectron spectroscopy analysis, it was found that the formation of ZnC bonds allows for the stable operation of the proposed RGO-embedded ZnO TFT. These results will provide important information for the design of high-mobility TFT architectures for various applications.

[en] In this paper, improved uniformity in the resistive switching (RS) characteristics of ZnO-based memristors using Ti sub-oxide layers (metallic TiO_x, insulating TiO_y) is reported. Compared with Pt/Ti/ZnO/Pt cells, more reliable and reproducible RS operation was observed in Pt/TiO_x (or TiO_y)/ZnO/Pt cells, particularly with insulating TiO_y, because Ti sub-oxide layers play the role of oxygen reservoirs that help rupture the conducting filament. By comparison, Pt/TiO_y/ZnO/Pt cells exhibited the best performance, with a large on/off ratio (∼10⁵) at a read voltage of 0.4 V, and highly stable low- and high-resistive state operation for 100 direct-current sweep cycles. (paper)

[en] This paper reports the bipolar resistive switching characteristics of TaN_x-based resistive random access memory (ReRAM). The conduction mechanism is explained by formation and rupture of conductive filaments caused by migration of nitrogen ions and vacancies; this mechanism is in good agreement with either Ohmic conduction or the Poole-Frenkel emission model. The devices exhibit that the reset voltage varies from −0.82 V to −0.62 V, whereas the set voltage ranges from 1.01 V to 1.30 V for 120 DC sweep cycles. In terms of reliability, the devices exhibit good retention (>10⁵s) and pulse-switching endurance (>10⁶ cycles) properties. These results indicate that TaN_x-based ReRAM devices have a potential for future nonvolatile memory devices