[en] To compare liver hemangioma with hepatocellular carcinoma (HCC), as seen on superparamagnetic iron oxide (SPIO)-enhanced MR images. The study involved 30 patients with 51 focal hepatic mass lesions (31 hemangiomas, 20 HCCs). Breath-hold T1-weighted fast low angle shot (FLASH) and respiratory-triggered T2-weighted turbospin echo (TSE) images were obtained at 1.5T before and after intravenous administration of SPIO particles. For quantitative analysis, percentage signal intensity change (PSIC) and contrast-to-noise ratio (CNR) of the lesions were calculated for T1-weighted FLASH and T2-weighted TSE before and after intravenous administration of SPIO particles. In addition, lesion conspicuity and imaging artifacts were analyzed qualitatively. After SPIO administration, percentage signal intensity increase on T1-weighted FLASH images was 73.0 ± 22.1% for hemangiomas and 21.8 ±12.6% for HCCs, the difference being significant (p less than 0.05). Taking a signal increase of 40% on postcontrast T1-weighted FLASH as the cut-off value, sensitivity and specificity for hemangiomas were 96.8% and 100%, respectively. In addition, the percentages of signal intensity loss on T2-weighted TSE images for hemangiomas and HCCs were 35.5 ± 17.2% and 0.2 ± 10.5%, respectively (p less than 0.05). A comparison of lesion to liver CNR before and after SPIO infusion showed readings-for hemangiomas and HCCs, respectively- of 15.4 ± 6.0 and 4.7 ± 4.4 on T1-weighted FLASH images, and -2.6 ± 0.7 and 2.7 ± 4.4 on T2-weighted TSE images (p less than 0.05). Qualitative analysis indicated that the conspicuity of HCCs was noticeably greater on postcontrast T2-weighted TSE images than on precontrast images (p less than 0.05). The positive enhancement seen on T1-weighted FLASH images and the negative enhancement on T2-weighted TSE observed in liver hemangiomas after the administration of SPIO particles are valuable diagnostic features that can help characterize hemangiomas and differentiate them from HCCs. (author)

[en] Small angle neutron scattering (SANS) has been a very powerful tool to study nanoscale (1-100 nm) bulk structures in various materials such as polymer, self assembled materials, nano-porous materials, nano-magnetic materials, metal and ceramics. Understanding the importance of the SANS instrument, the 8m SANS instrument was installed at the CN beam port of HANARO in 2001. However, without having a cold neutron source, the beam intensity is fairly low and the Q-range is rather limited due to short instrument length. In July 1, 2003, therefore, the HANARO cold neutron research facility project was launched and a state of the art 40m SANS instrument was selected as top-priority instrument. The development of the 40m SANS instrument was completed as a joint project between Korea Advanced Institute of Science and Technology and the HANARO in 2010. Here, we report the specification of a state of art 40m SANS instrument at HANARO

[en] An instrumented capsule was developed to be able to measure fuel characteristics, such as fuel temperature, internal pressure of fuel rod, fuel pellet elongation, and neutron flux, etc., during the irradiation test of nuclear fuel in HANARO. The instrumented capsule for measuring and monitoring fuel centerline temperature and neutron flux was designed and manufactured. And then, to verify the design of the instrumented capsule in the test hole, it was successfully irradiated in the test hole of HANARO from March 14, 2003 to June 1, 2003 (53.84 full power days at 24 MW). In the year of 2004, 3 test fuel rods and the 03F-05K instrumented fuel capsule were designed and fabricated to measure fuel centerline temperature, internal pressure of fuel rod, and fuel axial deformation during irradiation test. Now, this capsule was successfully irradiated in the test hole OR5 of HANARO reactor from April 27, 2004 to October 1, 2004 (59.5 full power days at 24-30 MW). The capsule and fuel rods have been be dismantled and fuel rods have been examined at the hot cell of IMEF. The instrumented fuel capsule(05F-01K) was designed and manufactured for a design verification test of the dual instrumented fuel rods. The irradiation test of the 05F-01K instrumented fuel capsule will be carried out at the OR5 vertical experimental hole of HANARO

[en] A high-current electron beam generator has been developed. The energy and the average current of the electron beam are 2 MeV and 50 mA, respectively. The electron beam generator is composed of an electron gun, RF acceleration cavities, a 260-kW RF generator, electron beam optics components, and control system, etc. The electron beam generator will be used for the development of a millimeter-wave free-electron laser and a high average power infrared free-electron laser. The machine will also be used as a user facility in nuclear industry, environment industry, semiconductor industry, chemical industry, etc. (author). 15 tabs., 85 figs

[en] An isotope selective ionization of ⁶⁷Zn based on the polarization selection rule is demonstrated. Two parallel polarized pulsed lasers are provided in a counter propagation configuration to excite the ground state ⁶⁷Zn isotope to the 4s5d ³D₁ state via the 4s4p ³P₁ state. The highly-excited ⁶⁷Zn is ionized by a strong infrared laser pulse to the continuum. The isotope selectivity in this configuration is measured. In addition, the ionization cross-section from the 4s5d ³D₁ state is reported for the first time.

[en] An instrumented capsule was developed to be able to measure fuel characteristics, such as fuel temperature, internal pressure of fuel rod, fuel pellet elongation, and neutron flux, etc., during the irradiation test of nuclear fuel in HANARO. The instrumented capsule for measuring and monitoring fuel centerline temperature and neutron flux was designed and manufactured. And then, to verify the design of the instrumented capsule in the test hole, it was successfully irradiated in the test hole of HANARO from March 14, 2003 to June 1, 2003 (53.84 full power days at 24 MW). In the year of 2004, 3 test fuel rods and the 03F-05K instrumented fuel capsule were designed and fabricated to measure fuel centerline temperature, internal pressure of fuel rod, and fuel axial deformation during irradiation test. Now, this capsule was successfully irradiated in the test hole OR5 of HANARO reactor from April 27, 2004 to October 1, 2004 (59.5 full power days at 24-30 MW). The capsule and fuel rods have been be dismantled and fuel rods have been examined at the hot cell of IMEF. The instrumented fuel capsule (05F-01K) was designed and manufactured for a design verification test of the dual instrumented fuel rods. The irradiation test of the 05F-01K instrumented fuel capsule will be carried out at the OR5 vertical experimental hole of HANARO

[en] Neutron radiography facility (NRF), is the non-destructive inspection equipment that use intrinsic matter penetration properties of neutron, in the field of NDT (Non-Destructive Testing) with more advantage as compare to X-ray radiography. Neutron radiography is based on the interaction of neutron with nucleus instead of the electron as in X-ray radiography. Even radioisotopes in the same element can be distinguished by the neutron radiography due to its specific cross-section properties. Namely, the neutron radiography is recognized as a complementary technique to the X-ray radiography. In this paper, although neutron radiography facility is generally installed only at high-flux research reactors, the feasibility of thermal column in AGN-201K was evaluated by using MCNP code. Specially, thermal flux level at the exit of beam line through collimator was evaluated in order to check its feasibility for NRF.

[en] This work developed improved slip factor model and correction method to predict flow through impeller in forward-curved centrifugal fan. Both steady and unsteady three-dimensional CFD analyses were performed to validate the slip factor model and the correction method. The results show that the improved slip factor model presented in this paper could provide more accurate predictions for forward-curved centrifugal impeller than the other slip factor models since the present model takes into account the effect of blade curvature. The correction method is provided to predict mass-averaged absolute circumferential velocity at the exit of impeller by taking account of blockage effects induced by the large-scale backflow near the front plate and flow separation within blade passage. The comparison with CFD results also shows that the improved slip factor model coupled with the present correction method provides accurate predictions for mass-averaged absolute circumferential velocity at the exit of impeller near and above the flow rate of peak total pressure coefficient

[en] In order to investigate dynamic properties of polypyrrole (Ppy) thin films in various electrolyte solutions, NaCl, NaClO₄, NaNO₃, NaDS, LiClO₄, KClO₄, resonant frequency and resistance were measured through electrical polymerization process using a quartz crystal analyzer (QCA). The surface structure was observed by using atomic force microscopy (AFM). A diagram of the resonant frequency and resistance (F-R diagram) was used to interpret the results and compared with AFM photograph. When the Ppy film is polymerized onto the AT-cut quartz electrode crystal, it behaves as a rigid elastic layer at the initial stage. Then, it turns into a viscoelastic layer as polymerization. This is due to the penetration of electrolytes into the film. The size, mass and mobility of the hydrated cation and anion of the electrolyte affected the degree of the viscoelastic change of the polypyrrole thin films

[en] The electronic and magnetic properties of the Co2FeGe full Heusler alloy in (001) thin film are investigated using the first-principles electronic structure calculations within the density functional theory. We employ various exchange correlation functionals including the local density approximation (LDA), the generalized gradient approximation (GGA), and the additional +U corrections for strong on-site Coulomb interaction of transition metal 3d states, aiming to examine the correlation effect on the electronic structures which determine the spin gap and thus the half-metallicity. Our results reveal that the Co2FeGe thin film is metallic in both LDA and GGA, while the +U correction opens up the spin gap for spin minority channel in GGA+U but not in LDA+U in contrast to its bulk alloy which is predicted to be half-metallic in both LDA+U and GGA+U approaches with total spin magnetic moment of 6 μB. It is found that the surface states developed around the Fermi level and the enhanced 3d eg-t2g band splitting for the spin minority channel due to the correlation effect play critical roles to determine the emergence of the half-metallicity.